SYSTEMS AND METHODS FOR DETERMINING AIR HUMIDITY AND USES THEREOF

Abstract

Procedure, comprehensive: Transmitting a multitude of signals from a single sensor, each at a different frequency; Receiving reflected signals of the transmitted signals; Changing the frequency of the transmitted signals to achieve a desired signal-to-noise ratio; Determining attenuation values ​​only for each of the reflected signals that have the same propagation time from transmission to reception; Determining differences between pairs of damping values; and Converting the differences into a measurement of relative humidity.

Description

AREA

[0001] The present description generally relates to methods and systems for determining relative humidity via ultrasonic sensors or other means and for adjusting one or more vehicle operating parameters based on the determination of humidity. GENERAL STATE OF THE ART / SUMMARY

[0002] One or more ultrasonic sensors can be mounted on a motor vehicle, for example, a hybrid electric vehicle (HEV), enabling distance measurement between the sensor and an external object. Such an ultrasonic sensor can consist of at least one piezoelectric disk and a diaphragm configured to convert electrical energy into mechanical energy and vice versa. Specifically, an oscillating voltage can be applied to the piezoelectric disk, causing the disk and diaphragm to vibrate and generate ultrasonic waves at a frequency based on the frequency of the voltage oscillation. After the waves are emitted, the sensors wait for echoes returning from the objects, and when the echoes interact with the sensor / diaphragm, the diaphragm is set into vibration.The piezoelectric disc, which is attached to the membrane, converts the vibration into voltage, and based on the time frame for sending and receiving the ultrasound wave, a distance determination to an object can be derived.

[0003] In a vehicle, ultrasonic sensors can be used, for example, to determine the distance between the vehicle and obstacles during assisted or fully automated parking. However, a number of factors can influence the operational use of ultrasonic sensors. These factors can include temperature, humidity, target angle, and reflective surface roughness. Because of these four variables, determining the humidity in a vehicle can be complex, especially if the vehicle does not have a dedicated humidity sensor. Furthermore, estimating the ambient humidity can be important for several engine operating parameters, such as the amount of exhaust gas recirculation (EGR), ignition timing, air-fuel ratio, and so on.Knowing the ambient humidity can improve the operational use of ultrasonic sensors and can also be used to adjust relevant motor operating parameters.

[0004] Various types of sensors can be used to estimate ambient humidity. For example, oxygen sensors, such as a wideband lambda (universal exhaust gas oxygen - UEGO) sensor used to control the air-fuel ratio in the exhaust, can be used to estimate ambient humidity under selected conditions. Such oxygen sensors can be located in an exhaust duct or an intake air duct. In an example presented by Surnilla et al. in US 2014 / 0202426A1, an exhaust lambda sensor coupled to one engine bank can be used to opportunistically determine ambient humidity during conditions where that bank is selectively shut down and the other bank continues to burn. A variable voltage can be applied to the sensor, and a change in the pump current can be correlated with the ambient humidity.

[0005] However, the inventors of the present invention have recognized potential problems with such a system. For example, humidity measurements can be nonspecific, with humidity being estimated either opportunistically or as needed, if possible. Furthermore, frequent application of a variable voltage can lead to sensor blackening and eventual deterioration if an exhaust gas lambda sensor is used to detect humidity.

[0006] In another approach, US patent application US 2006 / 0196272A1 teaches the use of an ultrasonic sensor configured to transmit two different frequencies and to estimate humidity based on the difference between the attenuation losses obtained from the two different frequencies. However, the inventors of the present invention have recognized potential problems with such systems. For example, there may be certain periods during which humidity determinations using ultrasonic sensors may be distorted due to environmental or other variables. In another example, in cases where the ultrasonic sensor, or another ultrasonic sensor, may also be configured to determine distance measurements, it may be desirable to specify suitable frequencies for performing the distance measurements, if these suitable frequencies are based on the humidity determination.

[0007] Further state of the art is known from publications DE 10 2013 219 680 A1 and WO 2013 / 179 202 A2.

[0008] The object of the present invention is therefore to provide systems and methods to at least partially solve the aforementioned problems.

[0009] This problem is solved by the subject matter of the independent claims. Preferred embodiments of the invention are the subject matter of the dependent claims.

[0010] In one example, a method is provided that includes transmitting a multitude of signals from a single sensor, each at a different frequency; receiving reflected signals of the transmitted signals; changing the frequency of the transmitted signals to achieve a desired signal-to-noise ratio; determining attenuation values ​​for each of the reflected signals that have the same propagation time from transmission to reception; determining differences between pairs of attenuation values; and converting the differences into a value of the relative humidity.

[0011] As one example, the frequencies of the transmitted signals are changed in response to a finding that the reflected signals have, or would have, an undesirable signal-to-noise ratio. As another example, the frequency of the transmitted signals is changed in response to environmental conditions, including one or more of the following: ambient temperature, ambient humidity, and the propagation time from transmission to reception of the transmitted and reflected signals.

[0012] Another example further includes setting a distance detection threshold with the specified relative humidity, wherein setting the distance detection threshold involves: specifying suitable frequencies for performing a distance measurement; and selecting an optimal frequency for performing the distance measurements in response to the set distance detection threshold. As an example, the method further includes equipping a motor vehicle with the sensor and detecting the absence of a parked vehicle to assist in parallel parking by selecting a frequency or frequencies corresponding to the set distance detection threshold.

[0013] An ultrasonic sensor can be used to determine relative humidity. By changing frequencies in response to indications that the received signals have, or may have, undesirable signal-to-noise ratios, or in response to environmental conditions, accurate humidity measurements can be obtained from the ultrasonic sensor. Furthermore, by setting a distance detection threshold, optimal frequency(ies) can be selected for distance measurements, such as those performed during assisted or fully automated parking maneuvers.

[0014] The aforementioned advantages, as well as further advantages and features of the present description, will readily become apparent from the following detailed description, whether considered on its own or in conjunction with the accompanying drawings.

[0015] It is understood that the foregoing summary is provided to present, in simplified form, a selection of concepts that are described in more detail in the detailed description. It is not intended to mention important or essential features of the claimed subject matter, the scope of which is defined solely in the claims following the detailed description. Furthermore, the claimed subject matter is not limited to implementations that address the disadvantages mentioned above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows a schematic representation of an internal combustion engine. Fig. Figure 2 shows a block diagram of components of a vehicle system that uses ultrasonic sensor(s) to assist or control vehicle parking maneuvers. Fig. Figure 3A shows a diagram illustrating the effects of humidity and ultrasonic frequency on sound attenuation. Fig. Figure 3B shows a diagram illustrating the difference in sound attenuation for different ultrasonic frequencies at a given relative humidity. Fig. 3C graphically represents an exemplary transfer function for determining relative humidity as a function of a difference in sound attenuation for two ultrasonic frequencies. Fig. Figure 4 shows an exemplary high-level procedure for carrying out a determination of relative humidity using an ultrasonic sensor. Fig. Figure 5 shows an exemplary high-level procedure for implementing a variable frequency algorithm used by an ultrasonic sensor, as a sub-method of Fig. 4. Fig. Figure 6 shows an exemplary high-level procedure for performing a delta damping calculation as a sub-method of Fig. 4. Fig. Figure 7 shows an exemplary high-level procedure for using one or more in-vehicle cameras to select an appropriate ultrasonic sensor for performing a measurement of relative humidity. Fig. Figure 8 shows a schematic representation of an example UEGO probe. Fig. Figure 9 shows an exemplary high-level procedure for opportunistically performing a measurement of humidity using either an oxygen sensor or an ultrasonic sensor in response to ambient or vehicle operating conditions. Fig. Figure 10 shows a diagram illustrating the thermal conductivity of air as a function of ambient temperature and humidity. Fig. Figure 11 shows an exemplary high-level procedure for performing a diesel particulate filter regeneration process based on whether an object is detected that is positioned in an area near a vehicle exhaust. Fig. Figure 12 shows an exemplary high-level procedure for setting a distance detection threshold for an ultrasonic sensor. Fig. Figure 13 presents an example lookup table, which, in conjunction with the procedure from Fig. 12 can be used to select (an) optimal ultrasound frequency(ies) for distance measurements based on set distance detection thresholds. Fig. Figure 14 shows an exemplary timeline for carrying out a process to determine humidity based on vehicle operating conditions. Fig. Figure 15 shows an exemplary timeline for carrying out a DPF regeneration event, where conditions of the regeneration event may be based at least partially on a specification of the ambient humidity. DETAILED DESCRIPTION

[0016] The following description concerns systems and methods for performing measurements of relative humidity and adjusting vehicle operating parameters in response to the relative humidity measurement. Such measurements can be performed by a vehicle system that includes an internal combustion engine, and the vehicle may further be configured with one or more in-vehicle cameras and one or more ultrasonic sensors, such as the one described in Fig. 1. Vehicle system shown. In some examples, the vehicle may be a hybrid vehicle capable of operating for extended periods without its engine running. Knowledge of relative humidity can enhance functions such as assisted or fully automated parking maneuvers, facilitated by a parking assistance system, as shown in Fig. Figure 2 illustrates this. In some examples, humidity measurements can be determined using an ultrasonic sensor based on a relationship between sound attenuation, relative humidity, and ultrasonic frequency, as shown in Figure 2. Fig. Figure 3A illustrates this. For example, a difference in sound attenuation for a given pair of frequencies can allow an estimation of the ambient humidity, as shown by Fig. 3B is given. Such an estimate can be performed using a transfer function, which is given in Fig. 3C is graphically represented.

[0017] Fig. Figure 4 illustrates an exemplary high-level procedure for performing a humidity measurement using an ultrasonic sensor. As a sub-method of Fig. 4. A variable frequency algorithm, as in Fig. Figure 5 is shown and can be used to determine the sound attenuation for two or more ultrasonic frequencies, which can then enable a delta attenuation calculation, as in Fig. Figure 6 shows that the relative humidity can be measured by performing the variable frequency algorithm and the delta attenuation calculation.

[0018] In some examples, one or more in-vehicle cameras can be used to identify suitable objects of interest for performing the humidity determination process using an ultrasonic sensor. Accordingly, a method for detecting suitable objects using one or more cameras is described in Fig. 7 illustrates.

[0019] In other examples, certain conditions may not be optimal for determining humidity using an ultrasonic sensor, and other means may be desirable, and vice versa. For instance, an oxygen sensor positioned in the intake or exhaust manifold of a vehicle engine may be used instead of an ultrasonic sensor to indicate humidity under certain vehicle operating conditions. Such an example of an oxygen sensor is described in Fig. Figure 8 illustrates and provides an example procedure for selecting whether to measure humidity using an oxygen sensor or an ultrasonic sensor. Fig. 9 illustrates.

[0020] The in Fig. The vehicle system depicted in Figure 1 may, in some examples, include a diesel engine and thus a diesel particulate filter (DPF) for capturing and storing soot from the engine. The regeneration of such a filter can involve high exhaust temperatures, and therefore, in some examples, it may be desirable to specify whether an object is located near the exhaust before the regeneration process is carried out. Furthermore, distance thresholds for the object may, in some examples, be set depending on the relative humidity and temperature at a location near the exhaust. For example, the thermal conductivity of air can vary depending on humidity and temperature, as illustrated by the example in Figure 1. Fig. 10 shown in the diagram. Accordingly, a distance threshold for an object can be set in some examples based on a derived thermal conductivity of air, as in the one shown in Fig. The procedures shown in Figure 11 illustrate this. For example, setting a distance threshold value can enable DPF regeneration processes to be carried out more frequently.

[0021] As discussed above, humidity can introduce a noise factor into the operational use of an ultrasonic sensor. Therefore, knowledge of the ambient humidity can improve the operational use of the ultrasonic sensor in some cases. In one example, a distance detection threshold according to the one described in Fig. The 12 illustrated procedures can be set. As an example, setting the distance detection threshold might involve specifying suitable frequencies for performing a distance measurement using an ultrasonic sensor. In such an example, a lookup table, such as the one in Fig. 13 illustrated lookup table, in conjunction with the one in Fig. The 12 illustrated methods can be used to determine an optimal frequency for a desired operational use of the ultrasonic sensor.

[0022] Exemplary timelines for selecting the method for determining humidity based on vehicle operating parameters and for performing a DPF regeneration process at least partially based on a humidity determination are presented in Fig. 14 or Fig. 15 illustrated.

[0023] Fig. Figure 1 is a schematic representation showing a cylinder of a multi-cylinder engine 10 in an engine system 100. The engine system 100 can be coupled within a drive system of a road vehicle system 101. An outside air temperature (OAT) sensor 127 can be positioned on the outside of the vehicle system 101. The OAT sensor can estimate the ambient air temperature, which can be used for engine operation, and additionally, in some examples, the OAT sensor 127 can be used to trigger measurements of humidity according to a change in the ambient temperature. In some examples, one or more cameras 186 can be positioned at one or more locations (e.g., spots) on the vehicle and can be configured to capture images, including, among other things, the area around the vehicle. In some examples, one or more camera sensors (e.g.,187) may be configured to provide position information regarding one or more cameras 186. For example, if a camera is rotatable, the camera sensor(s) 187 may transmit the direction in which the camera is facing to a vehicle control unit (e.g., 12). In other examples where the camera is not rotatable, the camera sensor(s) 187 may still be configured to indicate a position and the direction in which the camera is facing. Additionally, one or more ultrasonic sensors 185 may be positioned at one or more locations on the vehicle and may be configured to measure the distance from the ultrasonic sensor(s) to an object of interest. For example, the ultrasonic sensor may be configured to transmit and receive signals in the form of sound waves.In some examples, an object of interest can be detected by the ultrasonic sensor(s) themselves. In other examples, one or more cameras can detect an object of interest, after which the ultrasonic sensor(s) can be used to derive a distance measurement between the ultrasonic sensor(s) and the object of interest. In still other examples, as described in more detail below, the ultrasonic sensor(s) can be used to obtain measurements of relative humidity.For example, certain conditions may trigger a request for a relative humidity measurement, where the certain conditions may include a change in temperature exceeding a predetermined temperature threshold, a change in ambient pressure exceeding an ambient pressure threshold, a time threshold for engine operation, or a distance traveled by the vehicle exceeding a threshold distance since a previous (e.g., the last) humidity measurement.

[0024] In particular, as described in more detail below, the ultrasonic sensor 185 can be used in some examples to obtain measurements of the proximity of a vehicle to an object(s) of interest (e.g., obstacles) during vehicle operation, such as an assisted or fully automatic parking maneuver. However, a noise factor for the ultrasonic sensor(s) 185 can be humidity. Thus, knowledge of the relative humidity can be used in some examples to set a detection threshold for the ultrasonic sensor, which may involve specifying suitable frequencies for performing distance measurements using the ultrasonic sensor. In other examples, knowledge of the relative humidity can improve engine operating conditions if such conditions are based on an accurate estimate of the relative humidity, as discussed in more detail below.

[0025] The engine 10 can be controlled, at least partially, by a control system comprising a controller 12 and by input from a driver 132 via an input device 130. In this example, the input device 130 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP. The combustion chamber (i.e., the cylinder) 30 of the engine 10 can include combustion chamber walls 32 with a piston 36 positioned therein. The piston 36 can be coupled to the crankshaft 40, so that an alternating motion of the piston is translated into a rotational motion of the crankshaft. The crankshaft 40 can be coupled to at least one drive wheel of a vehicle via an intermediate gear system. Furthermore, a starter can be coupled to the crankshaft 40 via a flywheel to enable the starting of the engine 10.

[0026] The combustion chamber 30 can draw in intake air from an intake manifold 44 via an intake port 42 and discharge combustion gases via the exhaust port 48. The intake manifold 44 and the exhaust port 48 can be selectively connected to the combustion chamber 30 via a corresponding intake valve 52 and exhaust valve 54. In some embodiments, the combustion chamber 30 can include two or more intake valves and / or two or more exhaust valves.

[0027] In this example, the inlet valve 52 and the exhaust valve 54 can be controlled by cam actuation via the corresponding cam actuation systems 51 and 53. The cam actuation systems 51 and 53 can each include a fixed cam profile or can include one or more cams and utilize one or more cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or variable valve lift (VVL) systems, which can be operated by the controller 12 to vary the valve operation. The position of the inlet valve 52 and the exhaust valve 54 can be determined by the position sensors 55 and 57, respectively. In alternative embodiments, the inlet valve 52 and / or the exhaust valve 54 can be controlled by an electric valve actuator.For example, cylinder 30 may alternatively include an inlet valve controlled by an electric valve actuation and an exhaust valve controlled by cam actuation, including CPS and / or VCT systems.

[0028] The fuel injection device 66 is shown to be directly coupled to the combustion chamber 30 for injecting fuel. Thus, the fuel injection device 66 provides a so-called direct injection of fuel into the combustion chamber 30. The fuel injection device can be located, for example, in the side or top of the combustion chamber. Fuel can be supplied to the fuel injection device 66 by a fuel system (not shown) that includes a fuel tank, a fuel pump, and a fuel distributor, which can be a common fuel distributor.

[0029] The intake manifold 44 can include a throttle 62 with a throttle valve 64. In other examples, however, the throttle can be located in the intake duct 42. In this particular example, the position of the throttle valve 64 can be varied by the control unit 12 via a signal provided to an electric motor or actuator included in the throttle 62, a design commonly referred to as an electronic throttle control (ETC). In this way, the throttle 62 can be operated to vary the intake air and / or EGR supplied to the combustion chamber 30, among other engine cylinders. The position of the throttle valve 64 can be provided to the control unit 12 by the throttle position signal TP. The intake duct 42 can include a mass airflow sensor 120 and a manifold pressure sensor 122 to provide the corresponding MAF and MAP signals to the control unit 12.

[0030] In some examples, the engine 10 may further include a compression device such as a turbocharger or a supercharger, which comprises at least one compressor 162 arranged along the intake manifold 44. In the case of a turbocharger, the compressor 162 may be driven at least partially by a turbine 164 (e.g., via a shaft) arranged along an exhaust duct 48. In the case of a supercharger, the compressor 162 may be driven at least partially by the engine and / or an electric machine and may not include a turbine. Therefore, the degree of compression (e.g., boost pressure) supplied to one or more cylinders of the engine via a turbocharger or supercharger can be varied by the control unit 12. Furthermore, a sensor 123 may be arranged in the intake manifold 44 to provide a boost pressure signal to the control unit 12.

[0031] The engine 10 may further include a high-pressure EGR system 150. The high-pressure EGR system 150 may include an EGR line 152, which is connected to the outlet 48 upstream of the turbine 164 and to the inlet 44 downstream of the compressor 162. The high-pressure EGR system 150 may include an EGR valve 154, which is arranged along the EGR line 152 to control the exhaust gas flow through the EGR system 150. The engine 10 may further include a low-pressure EGR system 156. The low-pressure EGR system 156 includes an EGR line 158, which is connected to the outlet 48 downstream of the turbine 164 and to the inlet 44 upstream of the compressor 162. The low-pressure EGR system 156 can include an EGR valve 160 arranged along the EGR line 152 to control exhaust gas flow through the EGR system 156.

[0032] Control 12 is in Fig. 1 is represented as a microcomputer which includes a microprocessor unit 102, input / output ports 104, an electronic storage medium for executable programs and calibration values, which in this specific example is represented as a read-only memory chip 106, a direct access memory 108, a keep-alive memory 110 and a data bus.In addition to the signals discussed previously, the control unit 12 can receive various signals from sensors coupled to the engine 10, including the mass air flow (MAF) measurement from a mass air flow sensor 120; the engine coolant temperature (ECT) from a temperature sensor 112 coupled to a cooling sleeve 114; a profile ignition pickup (PIP) signal from a Hall effect sensor 118 (or another type) coupled to the crankshaft 40; the throttle position (TP) from a throttle position sensor; and the manifold absolute pressure (MAP) signal from sensor 122. The engine speed signal (RPM) can be generated by the control unit 12 from the PIP signal. The manifold pressure signal MAP from the manifold pressure sensor can be used to provide an indication of vacuum or pressure in the intake manifold.Other sensors may include camera sensors 187, ultrasonic sensors 185, OAT sensors 127, etc.

[0033] The storage medium with read-only memory 106 can contain computer-readable data that represents instructions which can be executed by the processor 102 to carry out the procedures and control strategies described below, as well as other variants that are anticipated but not explicitly listed.

[0034] Additionally, the controller 12 can receive data from an in-vehicle navigation system 34 (e.g., a global positioning system (GPS)) with which a vehicle operator can interact. The navigation system 34 may include one or more position sensors to assist in estimating vehicle speed, vehicle altitude, vehicle position / location, etc. This information can be used to derive engine operating parameters, such as local atmospheric pressure. The controller 12 can also be configured to receive information via the internet or other communication networks 13. In some examples, information received from the GPS can be combined with information available via the internet to determine local weather conditions, etc.In some examples, the controller 12 can use the internet to obtain updated software modules that can be stored in non-volatile memory.

[0035] As described above, shows Fig. 1 merely one cylinder of a multi-cylinder engine; however, it should be noted that each cylinder may also contain its own set of inlet / outlet valves, fuel injection device, spark plug, etc.

[0036] In some examples, the engine may be a diesel engine configured to burn diesel fuel (e.g., mineral oil diesel or biodiesel) via compression ignition. However, in other examples, the engine may not be a diesel engine. For brevity, this is illustrated Fig. 1. An engine in which some of the components are contained in a diesel engine and in which the remaining components can be contained in either a diesel or a non-diesel engine. Thus, the rest of the description of Fig. 1 Components that are specific to a diesel engine are highlighted as diesel engine specific.

[0037] According to the illustration, the exhaust gas sensor 126 is coupled to the exhaust gas channel 48 upstream of the emission control device 70. The sensor 126 can be any suitable sensor for providing an indication of an exhaust air-fuel ratio, such as a linear lambda probe or UEGO (universal or wide-range exhaust oxygen), a dual-state lambda probe or EGO, a HEGO (heated EGO), or a NOₓ sensor. x -, HC or CO sensor. A detailed embodiment of a UEGO probe is described in relation to Fig. This sensor can be used to estimate ambient humidity under selected vehicle operating conditions, as described in section 8. In some examples, the engine system may include dedicated ambient humidity sensors to measure relative humidity when a humidity estimate is triggered. A change in ambient temperature, as measured or estimated by the OAT-127 and / or IAT-125 sensor, can trigger a humidity measurement. Similarly, a change in ambient pressure, as estimated by the BP-128 sensor, can trigger a humidity measurement. A humidity measurement can also be triggered if the difference between the current ambient temperature or pressure and the ambient temperature or pressure at the last known humidity measurement exceeds a certain threshold.The humidity sensors can be positioned on the intake duct 42 and / or the exhaust duct 48 upstream of an emission control device 70. By actively sensing the humidity under ambient conditions where changes in humidity are expected, instead of (or in addition to) opportunistic humidity sensing where possible, a more accurate and reliable humidity estimate can be provided for engine control, and unnecessary humidity measurements can be avoided.

[0038] In some examples, humidity can be estimated either from the ultrasonic sensors or by other means, such as the UEGO probe 126. Such a procedure may involve: reporting the relative humidity from differences between pairs of reflected signals from a single ultrasonic sensor coupled to a vehicle, each of the reflected signals having a substantially equivalent travel time from an object back to the ultrasonic sensor; reporting the relative humidity from one or more sensors coupled to the vehicle other than the ultrasonic sensor (e.g., UEGO probe); and selecting which method to use to report the relative humidity in response to environmental or vehicle operating conditions.This allows for timely and accurate derivation of humidity estimates, which can improve vehicle operating conditions if such operating conditions are based on accurate humidity estimates.

[0039] According to the illustration, the emission control device 70 is arranged downstream of the exhaust gas sensor 126 along the exhaust gas channel 48. The device 70 can include one or more components, such as at least one three-way catalyst, a lean NOx trap, a diesel oxidation catalyst (DOC), a selective catalytic reduction (SCR) catalyst, an oxidation catalyst, etc. An ammonia (or urea) supply system can be coupled to the SCR catalyst or located upstream of the SCR catalyst to supply reducing agents to the SCR catalyst.

[0040] In an example where the engine includes a diesel engine, at least one diesel particulate filter (DPF) 72 can be coupled downstream of the emission control device 70 to capture soot. The DPF can be made from a variety of materials, including cordierite, silicon carbide, and other high-temperature oxide ceramics. Thus, the DPF may have a finite capacity for capturing soot. Therefore, the DPF can be regenerated periodically to reduce soot deposits in the filter so that flow resistance due to soot accumulation does not reduce engine power. Filter regeneration can be achieved by heating the filter to a temperature at which soot particles burn off faster than new soot particles can be deposited, for example, 400–600 °C.In one example, the DPF can be a catalyzed particulate filter that contains a washcoat made of precious metal, such as platinum, to lower the combustion temperature of the soot and also to oxidize hydrocarbons and carbon monoxide to carbon dioxide and water.

[0041] In an example where the engine may be a diesel engine, a hydrocarbon (HC) reducing agent supply system 74 can be used to supply HC from the fuel tank or a reservoir to the exhaust system to generate heat for heating the particulate filter 72 for regeneration purposes. Alternatively or additionally, late fuel injection (e.g., during an exhaust stroke) can be used to increase the exhaust temperature.

[0042] In the example case where the vehicle engine is a diesel engine, temperature sensors 76 and 78 can be located upstream and downstream of the DPF 72, respectively. Temperature sensors 76 and 78, or additional temperature sensors, can also be located inside the DPF, or the DPF temperature (or exhaust gas temperature) can be estimated based on operating conditions using an exhaust gas temperature model. A differential pressure signal can be determined from pressure sensors 80 and 82 upstream and downstream of the DPF 72, respectively. It should be noted that a single differential pressure sensor can also be used to measure the differential pressure throughout the entire DPF 72. A single port gauge pressure sensor (SPGS) can also be used.

[0043] It is understood that alternative configurations of the emission control system can be used in alternative embodiments. For example, the emission control device 70 can be coupled downstream of the DPF. Furthermore, in other examples, a variety of diesel particulate filters can be included in the emission control system. Additionally, the SCR catalyst may not be included in the emission control system in other examples. Each catalyst, filter, etc., can be enclosed within a single housing or, alternatively, enclosed via separate housings. It is understood that numerous configurations are possible and those described in Fig. The configuration shown in Figure 1 is exemplary. Furthermore, as mentioned above, a reducing agent (e.g., ammonia or urea) injection system can be coupled to the outlet to inject urea upstream of the emission control device 70.

[0044] To regenerate the DPF, a regeneration injection strategy can be implemented. This strategy can employ an injection profile that includes a variety of injection events, such as a pre-fuel injection, a main fuel injection, a near-post-fuel injection, and / or a distant post-fuel injection. It is understood that the aforementioned fuel injections can, in other embodiments, include a variety of injection events. Thus, the DPF can be regenerated while the engine is running. For example, the temperature before a DOC and after a DPF can be controlled to a desired value to promote the combustion of particulate matter within the DPF by adjusting the quantity of the various injections. In this example, a target temperature can be set after the DOC and before the DPF to facilitate DPF regeneration.In other examples, a heating device 75, configured to increase the temperature of the DPF, can be used for DPF regeneration.

[0045] As discussed, the regeneration of the DPF, which is coupled to the underbody of a motor vehicle, can involve burning off particles (e.g., soot) deposited in the particulate filter, causing hot gases to escape from the rear (e.g., an exhaust) of the vehicle. Therefore, in some examples, it may be desirable to indicate whether an object falls within a specified threshold distance from the exhaust. Such an object can be identified, for example, by one or more in-vehicle cameras (e.g., 186) and / or one or more ultrasonic sensors (e.g., 185).In some examples, selecting an ultrasonic sensor to use when performing a distance measurement between the sensor and an object may involve selecting the sensor based on a transmission path that overlaps at least a portion of the hot gases exiting the rear of the vehicle, and may further depend on the object being within the sensor's transmission path, as identified by one of the cameras. In such a case, if an object falls below a specified threshold distance from the exhaust (within a threshold distance of the hot gases exiting the rear of the vehicle), the DPF regeneration process may be postponed or aborted.Furthermore, ambient humidity and temperature can affect the thermal conductivity of air, and thus, in some examples, it may be desirable to obtain measurements of the ambient temperature and humidity so that a threshold distance, the distance the object can be from the exhaust, can be set according to the thermal conductivity of air. Specifically, in some examples, the thermal conductivity of air can be determined based on a given relative humidity and air temperature, with the air temperature measured near the point where hot gases exit the rear of the vehicle. Setting the threshold distance based on the measured thermal conductivity of air may involve lowering the distance threshold as the thermal conductivity decreases and raising it as the thermal conductivity increases.In this way, DPF regeneration processes can be started and completed more frequently than if the distance threshold were not adjustable. In response to a signal indicating that an object is positioned at a greater distance than the threshold, the object and an area near the rear of the vehicle can continue to be monitored during the regeneration process using one or more cameras and / or one or more ultrasonic sensors. In such an example, the regeneration process can be terminated if it is determined that the object or other objects are closer than the set threshold distance during the regeneration process.

[0046] With reference to Fig. Figure 2 is an exemplary parking aid system 200, which uses an ultrasonic sensor 185, shown schematically. The system 200 includes components of a typical vehicle, which includes a powertrain control module 208, illustrated as a combined control unit consisting of the controller 12 and the transmission control unit 210. The system 200 further includes one or more ultrasonic sensors 185, which are mounted at various locations on the vehicle and configured to provide inputs to a parking aid module 205. For example, the ultrasonic sensors can be positioned on the front, side, rear, or any combination thereof of the front, rear, and / or side of the vehicle. Such a system 200, as described in this disclosure, is generally applicable to various types of vehicles, including small and large cars, trucks, vans, off-road vehicles, etc., which can use an ultrasonic sensor.

[0047] The term "powertrain" refers to a power generation and supply system that includes an engine and a transmission, and is used to describe the propulsion system in a motor vehicle. The powertrain control module 208 performs engine and transmission control operations using a controller 12 and a transmission control unit 210, respectively. The controller 12 detects data from various sections of the engine and can adjust the fuel supply, ignition timing, intake air flow rate, and various other known engine operations, as described above with reference to Fig. 1. The transmission control unit 210 detects the engine load and vehicle speed to determine the gear position to be engaged in the transmission. For the purpose of description, Fig. Figure 2 shows only a few components of the powertrain control module 210. However, it is understood by those skilled in the art that the powertrain control module 208 can be operatively connected to a number of sensors, switches or other known devices in order to obtain vehicle information and control various vehicle operations.

[0048] The Parking Assistance Module 205 provides functions such as automatic parking, parallel parking, obstacle detection, etc., resulting in a convenient or fully automated parking process. For example, using the Parking Assistance Module 205, the vehicle can steer itself into a parking space with little or no input from the driver. During this process, the module detects objects that pose a collision risk and issues a warning. Detection and warning are performed by a number of sensors, such as the Ultrasonic Sensor 185, which work together to determine the distance between the vehicle and surrounding objects. However, as discussed above and described in more detail below, humidity can introduce noise that affects the operational performance of the Ultrasonic Sensor.Accordingly, in some examples, the relative humidity can be determined either via the ultrasonic sensor itself or via other sensors (e.g., the UEGO probe) in the vehicle, thus improving the operational use of the ultrasonic sensor. In some examples, one or more cameras positioned at one or more locations on the vehicle can be used to detect objects of interest, allowing the humidity to be calculated via the ultrasonic sensor(s), as described in more detail below. In such an example, a procedure may involve selecting one from a variety of ultrasonic sensors positioned around a motor vehicle, at least partially based on one or more images from one or more cameras positioned around the motor vehicle.In some examples, the selected sensor can be chosen based on an object identified by one of the cameras located within a transmission path of the selected sensor. In some examples, the object can be specified as stationary relative to the vehicle. For example, in some examples, the cameras can indicate that the object is stationary. In another example, the selected sensor can be chosen based on a target vehicle traveling within a transmission path of the selected sensor, traveling at a speed substantially equal to the speed of the vehicle, and maintaining a substantially constant distance from the vehicle. Furthermore, in some examples, the one or more cameras can function to additionally or alternatively provide images and approximate distance information (e.g.,communicate (via object recognition analysis) during an assisted or fully automated parking process.

[0049] The ultrasonic sensor 185 can detect obstacles on either side of the vehicle as well as in front of or behind the vehicle, and vehicle modules, such as a steering wheel module (not shown), a braking system (not shown), a parking aid module (205), etc., can use this information. Thus, for the purposes of illustration, the one or more ultrasonic sensors 185 are coupled to the parking aid module, although this representation is for illustrative purposes only and is not to be understood as limiting. For the sake of brevity, however, a detailed description of other possible uses of one or more ultrasonic sensors is not discussed here. It is understood, however, that uses of the ultrasonic sensor(s) other than parking aid according to the methods described herein are possible without deviating from the scope of this disclosure.

[0050] The one or more ultrasonic sensors 185 can be configured to include a transmission (transmitting) means designed to transmit ultrasonic waves and a receiving means designed to receive the waves reflected by an object near the vehicle, such as the obstacle 220. A propagation time, which includes the time between the transmission and reception of the ultrasonic wave signal, can be determined, and a distance between the sensor and the obstacle (for example) can be specified based on the formula d = t * c / 2, where c is the speed of sound and t is the propagation time. This distance information can then be provided, for example, to the parking aid module 205 (or another relevant module). Such object detection functions of ultrasonic sensors are well known to those skilled in the art and are not discussed in detail in the present disclosure.

[0051] As discussed above, the operational use of one or more ultrasonic sensors can be subject to 185 noise factors. The four main noise factors affecting ultrasonic sensors are temperature, humidity, target angle, and reflective surface roughness. However, temperature can be compensated for by measuring the ambient air temperature, as discussed in more detail below. Furthermore, target angle and reflective surface roughness can be compensated for by using two or more wave frequencies transmitted by a single transmission medium, using only reflected signals with the same transit time from transmission to reception to determine distance measurements, as discussed in more detail below. However, compensating for humidity can be difficult in vehicles without a dedicated humidity sensor.

[0052] Methods for determining and compensating for humidity using an ultrasonic sensor (e.g., 185) are described below with reference to the Fig. 4-7, Fig. 9 and Fig. This is described in more detail in sections 11-12. In short, humidity affects the degree of attenuation (e.g., intensity loss) observed for different sound frequencies differently. Thus, relative humidity can be calculated by transmitting a variety of ultrasonic frequencies from an ultrasonic sensor and determining the attenuation of each frequency as a function of the difference in attenuation between pairs of frequencies. However, certain frequencies may be better suited for determining the differences in attenuation between pairs of frequencies in some examples. Accordingly, some examples may involve changing the frequencies of the transmitted signals in response to a finding that the reflected signals have, or would have, an undesirable signal-to-noise ratio.

[0053] For example, certain environmental conditions (e.g., wind, rain, snow, fog, temperature fluctuations, etc.) can affect the signal-to-noise ratio of specific frequencies. Therefore, if a particular frequency has an undesirable signal-to-noise ratio, or in other words, if the attenuation is too high, one or more additional frequencies can be transmitted and received, ensuring that only frequencies with the desired signal-to-noise ratios are used to measure relative humidity.

[0054] Thus, changing the frequency(ies) of the transmitted signals may involve changing the frequency(ies) in response to environmental conditions, including one or more of the following: ambient temperature, ambient humidity, and the travel time from transmission to reception of the transmitted and reflected signals.

[0055] For example, a previous humidity estimate can be used as a reference for changing the frequency(ies) to achieve desired signal-to-noise ratios. If, for instance, the humidity is expected to be high based on a previous estimate (which may be stored on the controller), one or more frequencies can be eliminated, and a different frequency can be selected. This selected frequency may be one that is likely to produce a desired signal-to-noise ratio for both the transmitted and received signals.

[0056] Similarly, in some examples, changing the frequency(ies) can be a function of a specified ambient temperature. In other examples, changing the frequency(ies) can be a function of the specified propagation delay from transmission to reception of the transmitted and reflected signals. For example, if the propagation delay from transmission to reception of the transmitted and reflected signals is not within an expected range, it can be specified that an environmental condition or other factor is affecting the signal-to-noise ratio and / or the integrity of the transmitted and received signal, and the frequency can be changed in an attempt to improve the signal-to-noise ratio and / or the signal integrity. In one example, such a factor affecting the propagation delay from transmission to reception of the transmitted and reflected signals could involve an ultrasonic sensor.Such an example might involve comparing the amplitude of the reflected signal with a reference amplitude based on the distance of an object from which the selected signal is reflected, and environmental conditions, including, but not limited to, humidity or temperature, to determine whether the sensors need cleaning. In an example where the sensor requires cleaning, changing the frequency(ies) might mitigate the problem. In other examples, a different ultrasonic sensor (instead of the dirty one) might be selected, perhaps in response to a statement that the transmission path of the ultrasonic sensor overlaps with an object of interest to be used for estimating relative humidity.Put another way, in some examples, the selection of a large number of sensors positioned around the vehicle may depend partly on whether any one of the many sensors needs to be cleaned.

[0057] With reference to Fig. Figure 3A shows diagram 300, which depicts sound attenuation as a function of the percentage relative humidity. Specifically, the percentage relative humidity is illustrated on the x-axis, and the sound attenuation in dB / km is illustrated on the y-axis. Line 302 indicates the ultrasonic frequency at 100 kHz, line 304 indicates 80 kHz, line 306 indicates 63 kHz, line 308 indicates 50 kHz, line 310 indicates 40 kHz, line 312 indicates 31.5 kHz, line 314 indicates 25 kHz, and line 316 indicates 20 kHz. As illustrated, sound attenuation increases with increasing ultrasonic wave frequency.

[0058] With reference to Fig. Figure 3B also illustrates diagram 340, which depicts sound attenuation as a function of the percentage of relative humidity. As in Fig. Line 302 in Figure 3A indicates the ultrasonic frequency at 100 kHz, and line 316 illustrates the ultrasonic frequency at 20 kHz. Arrow 342 is shown for illustration, indicating the difference in attenuation at 40 percent relative humidity between the ultrasonic frequencies at 100 kHz and 20 kHz.

[0059] With reference to Fig. Accordingly, diagram 360 is shown in 3C, which shows a difference in sound attenuation 362 between 100 kHz and 20 kHz over the range of the in the Fig. Figures 3A-3B represent the percentage relative humidity. Specifically, the difference in sound attenuation (delta attenuation) between 100 kHz and 20 kHz is illustrated on the x-axis, and the percentage relative humidity is shown on the y-axis. By plotting attenuation differences between two frequencies as a function of the percentage relative humidity, a simple transfer function, represented by arrows 364, can be used to determine the relative humidity. In other words, converting the attenuation difference can involve using a transfer function to transform the attenuation difference into a measurement of relative humidity. For example, a two-dimensional (2D) lookup table can contain known or predetermined values ​​corresponding to the relative humidity as a function of the attenuation differences between different frequencies.Once the sound attenuation difference between two different frequencies is known, such a lookup table can be used to determine the relative humidity. While sound attenuation differences for 100 kHz and 20 kHz are illustrated, it should be understood that the use of such frequencies to determine relative humidity is merely for illustrative purposes, and sound attenuation differences between two frequencies corresponding to frequencies other than 100 kHz and 20 kHz can be used equally well.

[0060] With reference to Fig. Figure 4 presents a high-level flowchart for an exemplary method 400 for determining humidity using an ultrasonic sensor. Specifically, method 400 may involve transmitting a plurality of signals from a single sensor, each at a different frequency, receiving reflected signals of the transmitted signals, and determining attenuation values ​​for each of the reflected signals that have the same propagation time from transmission to reception. Following the determination of attenuation values, method 400 may further involve determining differences between pairs of attenuation values ​​and converting these differences into a value of relative humidity.

[0061] Procedure 400 is performed with reference to the procedures described here and in Fig. 1 and Fig. The systems shown in section 2 are described, although it is understood that similar methods can be applied to other systems without deviating from the scope of this disclosure. Method 400 can be applied to a controller such as controller 12 in Fig. 1, and can be stored on the controller as executable instructions in non-volatile memory. Instructions for performing procedure 400 and the other procedures contained herein can be executed by the controller based on instructions stored in a memory of the controller and in conjunction with signals from sensors of the engine system, such as those referred to above. Fig. The controller can receive data from the sensors described in section 1. It can utilize actuators, such as an ultrasonic sensor (e.g., 185), etc., according to the following procedure.

[0062] Procedure 400 begins at 405 and may involve determining engine operating parameters. Operating conditions may be estimated, measured, and / or derived, and may include one or more vehicle conditions, such as vehicle speed, vehicle position, etc.; various engine conditions, such as engine status, engine load, engine speed, air-fuel ratio, etc.; various fuel system conditions, such as fuel level, fuel type, fuel temperature, etc.; and various evaporative emission system conditions, such as fuel vapor filter load, fuel tank pressure, etc.

[0063] Further on at 410, the procedure 400 can include measuring the ambient air temperature. As above with reference to Fig. As discussed in section 1, an outside air temperature (OAT) sensor (e.g., 127) positioned on the outside of the vehicle system (e.g., 101) can be used to determine the ambient air temperature. For example, the controller (e.g., 12) can send a signal to the OAT sensor to take a measurement of the ambient air temperature. The measurement can then be communicated back to the controller and stored, for example, on the controller. As discussed in more detail below, knowledge of the ambient air temperature can be taken into account when calculating the total attenuation difference between any two respective ultrasonic frequencies. In other words, converting the distances between pairs of attenuation values ​​into a value for relative humidity can be based on the measured ambient air temperature.

[0064] Further on at 415, the procedure 400 can involve performing a variable frequency algorithm (VFA) consisting of transmitting and receiving a variety of ultrasonic frequencies so that the attenuation difference(s) can be calculated. The performance of the (VFA) can be carried out according to the in Fig. The 5 procedures shown will be carried out in 500 cases.

[0065] With reference to Fig. Accordingly, Figure 5 presents a high-level flowchart for an exemplary procedure 500 for executing the VFA. Specifically, procedure 500 may include commanding the ultrasonic sensor to transmit an ultrasonic wave (chirp signal) at a first frequency, and then measuring and storing the transit time and intensity of the resulting echo. Next, procedure 500 may include commanding the ultrasonic sensor to transmit another chirp at a second frequency, and may further include subsequently measuring and storing the transit time and intensity of the resulting echo corresponding to the second chirp signal.

[0066] Procedure 500 is performed with reference to the procedures described here and in Fig. 1 and Fig. The systems described in Section 2 are described, although it is understood that similar methods can be applied to other systems without deviating from the scope of this disclosure. Method 500 may comprise a submethod of Method 400, and thus Method 500 may be executed by the controller (e.g., 12) and may be stored on the controller as executable instructions in non-volatile memory. Instructions for carrying out Method 500 and the other methods contained herein may be executed by the controller based on instructions stored in a memory of the controller and in conjunction with signals received from sensors of the motor system, such as those referred to above. Fig. The controller can receive data from the sensors described in section 1. It can utilize actuators, such as an ultrasonic sensor (e.g., 185), etc., according to the following procedure.

[0067] Method 500 begins at 505 and may involve transmitting a chirp signal with a first frequency. Specifically, the controller may instruct an electronic signal in the form of an oscillating voltage to be applied to the ultrasonic sensor (e.g., 185), the frequency of which may correspond to the desired frequency of the resulting ultrasonic wave. In some examples, the first frequency may be one at which the greatest attenuation would be expected, for example, 100 kHz. However, such an example is for illustrative purposes only and is not intended to be restrictive. Instead, any frequency between and including 20 kHz and 100 kHz may be transmitted first.

[0068] Further on at 510, the procedure 500 can include measuring and storing the transit time (t1) and intensity (i1) of the resulting echo corresponding to the transmitted chirp with the first frequency (f1). For example, the ultrasonic sensor can be configured to convert the received echo (received sound wave) into an oscillating voltage, where an electrical potential of the oscillating voltage can correspond to the intensity of the ultrasonic wave. A decrease in the intensity of the resulting echo can be interpreted as indicating attenuation of the ultrasonic wave from transmission to reception.

[0069] When receiving the echo corresponding to the transmitted chirp signal at the first frequency, the procedure can transition from step 500 to step 515. In step 515, the procedure can involve transmitting a chirp signal at a second frequency (f2). It is understood that the resulting echo at the first frequency can be received by the ultrasonic sensor before the second chirp signal is transmitted. The second chirp signal can have a different frequency than the first chirp signal and can be higher or lower than the frequency of the first chirp signal. For example, if the first frequency (f1) was 100 kHz, the second frequency (f2) could be 20 kHz. This example is for illustrative purposes only and is not intended to be restrictive.

[0070] Further on at step 520, procedure 500, similar to step 510, can involve measuring and storing the travel time (t2) and intensity (i2) of the resulting echo corresponding to the second chirp signal. As discussed above, the travel time and intensity of the second chirp signal can be stored on the controller (e.g., 12).

[0071] Further on at 525, procedure 500 can include determining whether additional accuracy (e.g., a better signal-to-noise ratio) is desired. In response to the transmission and reception of the first two ultrasonic waves (chirp signals), the controller can, for example, determine whether the signal-to-noise ratio of the received ultrasonic waves is sufficient for analysis (above a predetermined threshold). Depending on the contour and / or reflection angle of an object reflecting the transmitted waves, one or more of the received signals may, in some examples, fall below a threshold desired for accurate attenuation measurement. In another example, environmental conditions (e.g., wind, rain, etc.) may cause one or more of the received signals to fall below the predetermined threshold.In another example, environmental conditions could include one or more of the following: ambient temperature, ambient humidity, and the time it takes for the transmitted and reflected signals to be received. In further examples, a dirty ultrasonic sensor could cause one or more of the received signals to fall below the predetermined threshold.

[0072] In other examples, additional accuracy may be desired based on the intended use of the ultrasonic sensor for humidity measurement. If, in one example, a humidity estimate was previously provided using another method (e.g., UEGO, etc.) and the ultrasonic sensor was used to verify the accuracy of the previous measurement, a highly accurate measurement may not be required. In such an example, if the signal-to-noise ratio of the echoes received from the transmitted first and second frequencies exceeds the predetermined threshold, only two frequencies can be used to determine a humidity estimate. However, other examples may exist where more precise measurements of relative humidity are desired.Such an example might include a condition where a certain amount of time has elapsed since a previous humidity measurement, specifying that a change in atmospheric pressure has exceeded a threshold, specifying that a change in temperature has exceeded a threshold, and requiring an accurate derivation of the humidity for engine operation or parking assistance, etc.

[0073] In any of the examples mentioned above, or in other unspecified examples where additional accuracy is desired, Method 500 can be modified to 530. In Method 530, Method 500 can involve commanding the ultrasonic sensor to transmit one or more additional chirp signals (e.g., to change frequencies), each of which can be measured by the ultrasonic sensor for transit time and feedback intensity as described above. For example, a third, fourth, and fifth frequency can be transmitted, and each can be monitored for transit time and feedback intensity. This example is intended to be illustrative and not limiting. However, it is understood that the accuracy of the resulting humidity measurement, which is described in more detail below, can be increased with an increasing number of transmitted and received frequencies.In other words, frequencies of the transmitted signals can be changed in response to a determination that the reflected signals have, or would have, a desired signal-to-noise ratio below a predetermined threshold, whereby the changing of frequencies of the transmitted signals takes place before determining the differences between pairs of attenuation values ​​and converting the differences into a statement of relative humidity, as described in more detail below.

[0074] At step 525, the procedure can proceed to step 420 again, in response to the fact that two or more received frequencies have a sufficient signal-to-noise ratio for the desired accuracy of the resulting humidity measurement (described below). Fig. Return to 4.

[0075] At step 420 from Fig. Procedure 400 can include determining whether the propagation delays for each of the frequencies are equivalent. For example, if two frequencies were transmitted and received in step 415, it can be determined whether the two frequencies both have the same propagation delay. If three frequencies were transmitted and received in step 415, it can be determined whether all three frequencies have the same propagation delay, and so on. When calculating attenuation differences to determine relative humidity, only the frequencies with the same propagation delay can be processed further, as discussed in more detail below. In particular, attenuation values ​​can only be determined for each of the reflected signals that have the same propagation delay from transmission to reception, which can, for example, correct for variations in the target surface angle and the reflecting surface roughness.

[0076] If step 420 specifies that each of the propagation delays is equivalent for each of the frequencies transmitted and received in step 415, then procedure 400 can proceed accordingly to 425.

[0077] At 425, the procedure 400 can perform a Delta Attenuation Calculation (DAC) according to the one in Fig. The 6 procedures shown include.

[0078] With renewed reference to Fig. Section 6 presents an exemplary high-level procedure 600 for performing a DAC. In particular, frequencies determined according to the variable frequency algorithm (VFA) described above can be used. Fig. 5 was described, transmitted and received, and it was stated that they were the same in terms of Fig. The 4 propagation times described above are processed to calculate the attenuation of each of the individual frequencies, which can then be used to calculate attenuation differences between frequencies, so that the relative humidity can be determined.

[0079] Procedure 600 is performed with reference to the procedures described here and in Fig. 1 and Fig. The systems described in Section 2 are described, although it is understood that similar methods can be applied to other systems without deviating from the scope of this disclosure. Method 600 may comprise a submethod of Method 400, and thus Method 600 may be executed by the controller (e.g., 12) and may be stored on the controller as executable instructions in non-volatile memory. Instructions for carrying out Method 600 and the other methods contained herein may be executed by the controller based on instructions stored in a memory of the controller and in conjunction with signals from sensors of the motor system, such as those described above with reference to Fig. 1 described sensors, will be received.

[0080] Method 600 starts at 605 and can include calculating the attenuation (α) for each frequency with equivalent propagation times, as described by Method 400 from Fig. 4. In particular, the attenuation for a first frequency (f1) can be calculated using the following formula. S1=S0*e(−α1*z); where S0 is the original intensity of the undamped signal, z is the distance between the signal runs, S1 is the intensity of the received attenuated signal, and α1 is the attenuation coefficient for the frequency f1.

[0081] Rearranging equation (1) yields Damping=α1=ln(S1 / S0) / −z.

[0082] A total attenuation coefficient (αTot) consists of the attenuation due to temperature, humidity, target face angle, and reflective surface roughness. However, the effects of temperature, target face angle, and reflective surface roughness can be mitigated by performing the VFA according to the [reference to be added]. Fig. 5. Methods shown and furthermore by ensuring that only the frequencies with the same propagation delay are processed for the DAC as by the method described in Fig. The methods illustrated in Figure 4 can be subtracted. Since the temperature is known, its effect can be eliminated, and the target surface angle and the reflecting surface roughness do not change during the differential measurement of the frequency echo intensity, provided that the transit times for each of the analyzed frequencies are equivalent. Of the variables that influence the total attenuation coefficient (αTot), only the humidity is unknown and can exhibit a different attenuation coefficient for different frequencies.

[0083] After all attenuation values ​​for each of the analyzed frequencies have been calculated at 605, procedure 600 can accordingly proceed to 610. At 610, procedure 600 can include calculating the delta (Δ) attenuation values ​​for each of the analyzed frequencies. In particular, the delta attenuation due to humidity between two frequencies, for example f1 and f2, can, for the reasons described above, be equal to a total delta attenuation between f1 and f2. Thus, ΔαHumidity(f1−f2)=ΔαTotal(f1−f2)=Δα(f1−f2).

[0084] As illustrated by equation 3, two frequencies f1 and f2 are shown. However, it is understood that any frequency used in an example where more than two frequencies can be used to determine the value in Fig. 5 VFAs shown and those referred to here Fig. To perform the DAC calculation shown in section 6, the delta attenuation can be subtracted from all other frequencies to increase the accuracy of the measurement. Using the example of three frequencies, f1, f2, and f3, the delta attenuation calculation can include (f1-f2), (f1-f3), and (f2-f3), where the differences can be absolute values. A similar approach can be applied to examples using more than three frequencies.

[0085] Continuing at step 615, once the attenuation Δ for each pair of frequencies has been calculated, procedure 600 can involve storing the attenuation values ​​Δ and corresponding frequency values ​​in a table, where the table can be stored on the controller (e.g., 12). Procedure 600 can then return to step 425 of procedure 400.

[0086] At step 425 of procedure 400, procedure 400 can accordingly proceed to 430 as soon as the DAC is in accordance with the in Fig. The procedure described in Figure 600 was carried out. In Figure 430, the procedure 400 can involve determining the relative humidity using a lookup table stored on the controller. For example, a simple transfer function can be used so that the relative humidity for each pair of frequencies and the corresponding Δ attenuation for each pair of frequencies can be determined by correlating the transfer function with the lookup table stored on the controller (see Figure 6). Fig. 3C). In a case where several Δ attenuation values ​​are obtained for several pairs of frequencies, each Δ attenuation value and corresponding pairs of frequencies can be used to obtain a percentage relative humidity, and then all values ​​for relative humidity can be averaged by the controller to increase the reliability of the relative humidity measurement.

[0087] At step 420 of procedure 400, the procedure can proceed to step 435 if it is stated that not all of the propagation delays for the frequencies used in step 415 are equivalent, and can selectively involve discarding non-equivalent data. For example, data corresponding to frequencies that have the same propagation delays can be stored on the controller (e.g., 12), while data from frequencies without other equivalent propagation delays can be discarded. Further at step 440, it can be stated whether the remaining data set is sufficient to determine the humidity with the desired accuracy. For example, if it is stated that only two frequencies have the same propagation delays, but increased accuracy is desired (which may involve calculating the relative humidity from a data set containing more than two frequencies), the procedure can proceed to step 445.Therefore, if it is stated at 440 that the remaining data set is insufficient to calculate the relative humidity with the desired accuracy, the procedure can proceed from 400 to 445 and may involve determining the humidity by another means, provided the conditions permit. In some examples, determining the humidity can be achieved by using intake or exhaust oxygen sensor(s), as referred to in the [reference to be added]. Fig. 8-9 is discussed. If, at 440, it is stated that the remaining data set is sufficient to determine the relative humidity with the desired accuracy, procedure 400 may alternatively proceed to 425 and may include performing the DAC as described above.

[0088] In some cases, a vehicle may be equipped with multiple ultrasonic sensors. In such a case, it may be advantageous to prioritize the use of a specific sensor when measuring relative humidity. This might involve a situation where one or more sensors are reported to be dirty or malfunctioning. In such a case, it may be advantageous to use only the ultrasonic sensor(s) that are functioning correctly. In another example, it may be advantageous to detect an object using a secondary means and then preferably use an ultrasonic sensor positioned optimally to increase the likelihood of a successful relative humidity measurement.In some examples, detecting an object by a secondary means may include detecting an object using one or more in-vehicle cameras (e.g. 186).

[0089] For example, one or more cameras can be physically wired and communicatively coupled to a vehicle control system that includes a controller (e.g., 12). In another example, one or more cameras can additionally or alternatively communicate wirelessly with the controller to send and receive data. The wired communication can include USB technology, IEEE 1394 technology, optical technology, another serial or parallel interface technology, or any other suitable wired connection. Additionally or alternatively, wireless communication with the one or more cameras can include Bluetooth, an IEEE 802.11 protocol, an IEEE 802.16 protocol, a cellular signal, a shared wireless access protocol (SWAP-CA), a wireless USB protocol, or any other suitable wireless technology.The controller can receive one or more data files from one or more cameras, such as video data files, image data files, etc.

[0090] The one or more cameras may include cameras mounted on the front or rear bumper, or at any other suitable location on the front or rear of the vehicle. In some examples, more than one camera may be mounted on the front and / or rear. For example, two or more cameras may be mounted on the front of the vehicle, and two or more cameras may be mounted on the rear of the vehicle. Similarly, one or more side-facing cameras may be positioned at any suitable location on the vehicle to image objects on one or both sides of the vehicle. In some examples, more than one camera may be used to capture images corresponding to the left side of the vehicle, and more than one camera may be used to capture images corresponding to the right side of the vehicle.

[0091] In some examples, the one or more cameras may be fixed, while in other examples, the one or more cameras may be movable or rotatable relative to the vehicle. Additionally, some examples may include one or more fixed cameras and one or more movable cameras. The position of the one or more cameras on the vehicle may, in some examples, enable 360° viewing capabilities. As discussed, the one or more cameras may include cameras for capturing video and / or images. In other examples, the one or more cameras may include infrared cameras. Some implementations may include a variety of cameras, some of which may be configured to capture images and / or video, while one or more other cameras may be configured to capture infrared images.

[0092] In some examples, one or more cameras can be configured to detect objects near the vehicle. For instance, object detection systems (often referred to as obstacle detection systems) operated by using one or more vehicle cameras are well known in the trade. In particular, vehicle safety systems that enable the detection of obstacles such as pedestrians, bicycles, road barriers, other cars, etc., are generally known. A detailed discussion of all possible variations of object detection by using one or more cameras is beyond the scope of this disclosure. However, it is understood that any method known to a person skilled in the art can be used to perform object detection by using one or more cameras, as described in more detail below.As an illustrative example, an object recognition method might involve edge detection techniques, such as Canny edge detection, to locate edges in a single image captured by one or more cameras. An edge image corresponding to the single image can then be generated. A binary image can also be generated based on this edge image. Subsequently, one or more "blobs" within the binary image can be identified as corresponding to the one or more objects or obstacles. Based on an analysis of the blobs within the binary image, information such as shape, relative size, relative distance, etc., can be determined for each blob corresponding to the objects. As discussed, this example is intended to be illustrative and in no way limiting.Other methods and systems for object detection by the use of one or more cameras, which are known in the trade, can simply be used without deviating from the scope of the present disclosure.

[0093] In some examples, object detection can be performed using one or more cameras while the vehicle is stationary. In other examples, object detection can be performed using one or more cameras while the vehicle is in motion. In both examples, identified objects can be specified as stationary relative to the vehicle if the identified object does not change its position, size, or shape over a specified period. For example, multiple images can be captured by one or more cameras over a predetermined period, and if the position, size, and shape of a specific identified object do not change over the predetermined period, the identified object can be specified as stationary relative to the vehicle.In one example, such an object, which can be stationary relative to the vehicle, could be another vehicle traveling either in front of, to the left or right of, or behind it, with both vehicles traveling at substantially the same speed and in substantially the same direction. As discussed below, the identification of stationary objects relative to the vehicle can be used to select from a variety of ultrasonic sensors positioned on the vehicle to perform relative humidity measurements with an increased probability of obtaining accurate readings.

[0094] With reference to Fig. Figure 7 presents an exemplary high-level method for detecting objects using one or more available cameras positioned on a vehicle, enabling the selection of an ultrasonic sensor to perform a relative humidity measurement. Specifically, one or more cameras can be configured to scan the area surrounding the vehicle (e.g., near the vehicle) for stationary objects. Upon identifying a suitable object, an ultrasonic sensor can be selected from a variety of ultrasonic sensors positioned on the vehicle to perform a relative humidity measurement.In this way, relative humidity measurements can be performed with a higher probability of obtaining an accurate reading, without the unnecessary use of ultrasonic sensors under conditions where an accurate measurement is unlikely. By obtaining accurate relative humidity measurements, certain vehicle operating conditions, such as assisted or fully automatic parking functions, exhaust gas recirculation levels, ignition timing, etc., can be controlled more effectively.

[0095] Procedure 700 is performed with reference to the procedures described here and in Fig. 1 and Fig. The systems described in Section 2 are described, although it is understood that similar methods can be applied to other systems without deviating from the scope of this disclosure. Method 700 can be performed by a controller (e.g., 12) and can be stored on the controller as executable instructions in non-volatile memory. Instructions for performing Method 700 and the other methods contained herein can be executed by the controller based on instructions stored in a memory of the controller and in conjunction with signals from sensors of the motor system, such as those described above with reference to Fig. The controller can receive data from the sensors described in section 1. It can utilize actuators, such as an ultrasonic sensor (e.g., 185), one or more in-vehicle cameras (e.g., 186), etc., according to the following procedure.

[0096] Procedure 700 begins at 705 and may involve scanning the area around the vehicle with available cameras on the vehicle to detect objects suitable for performing a relative humidity measurement. In some examples, the scan of the area with available cameras may begin in response to one or more conditions that trigger a desired humidity measurement. For example, conditions that trigger a humidity measurement may include a specified change in ambient temperature exceeding an ambient temperature threshold since a previous (e.g., the last) humidity measurement. Another example may include a change in ambient pressure exceeding an ambient pressure threshold since a previous (e.g., the last) humidity measurement.Other examples might include a signal indicating a change in weather conditions, such as the activation of windshield wipers (not shown). Specifically, in response to the activation of the vehicle's windshield wipers, a signal can be sent to the control unit requesting a measurement of the relative humidity. This may involve the control unit first instructing one or more cameras to scan the surroundings for suitable objects.

[0097] In other examples, the search of the surroundings with available cameras can begin in response to the passage of a threshold time of engine operation or in response to the fact that the distance of the vehicle movement since a previous (e.g. the last) humidity measurement exceeds a predetermined distance.

[0098] As discussed above, in some examples the vehicle may be equipped with an in-vehicle navigation system (GPS) (e.g., 34) which includes one or more position sensors to assist in estimating vehicle speed, vehicle altitude, vehicle position / location, etc. Such information can be used to derive a local atmospheric pressure, whereby a change in the local atmospheric pressure above a threshold since a previous humidity measurement can trigger a request for a new humidity measurement, with suitable objects being identified via the in-vehicle camera(s). In still other examples, the controller (e.g., 12) may be configured to receive information via the internet or other communication networks.Information received from the GPS can, in some examples, be combined with information available via the internet to determine local weather conditions, etc. In some examples, a change in weather conditions, as indicated by the GPS and linked to the internet, can trigger a request for a relative humidity measurement, using available camera(s) to scan the surroundings for suitable objects to perform the relative humidity measurement.

[0099] In other examples, vehicle operating conditions may arise where one or more available cameras are in operation (e.g., assisted or fully automated parking maneuvers) and where a relative humidity measurement can be performed opportunistically. For instance, if a vehicle is performing a parking maneuver involving the use of one or more in-vehicle cameras, and the camera detects a suitable object for measuring relative humidity, a measurement can be taken, as described in more detail below.

[0100] If conditions are met for scanning the area around the vehicle for suitable objects to perform a relative humidity measurement, then the one or more cameras can be switched on accordingly at step 705 of procedure 700 to search for suitable objects. Specifically, a command can be sent from the controller (e.g., either a wired or wireless signal) to the one or more cameras to capture one or more images of the area around the vehicle. Images captured by the one or more cameras can, for example, be stored on the controller for further processing, as described in detail below. In some examples where one or more cameras are rotatable (e.g.,(movable, not stationary), the control system can be configured to capture images from different camera angles, allowing the area around the vehicle to be examined precisely for suitable objects.

[0101] As discussed here, suitable objects for performing a relative humidity measurement may include, among others, objects above a predetermined threshold size, objects with a predetermined shape, objects that are specified as stationary with respect to the vehicle, objects with a specified lack of surface roughness (e.g., a smooth surface), objects with a preferred orientation angle, and so on. Suitable objects may also include objects that are likely to reflect an ultrasonic signal back to an ultrasonic sensor, such that the transit time from transmission to reception of the signal can be the same for a variety of individual ultrasonic frequencies.

[0102] In response to a requirement to search the environment for suitable objects to perform a measurement of relative humidity, and in response to the acquisition of images via the one or more cameras at step 705, procedure 700 may accordingly proceed to 710.

[0103] In the case of 710, the procedure 700 may include indicating whether suitable objects are detected by the one or more cameras. As discussed above, the object detection analysis by the controller may be performed on images captured by the one or more cameras using any known means to determine whether objects suitable for measuring relative humidity are detected. In some examples, where multiple cameras are used to scan the environment for suitable objects, the controller may process images from all of the cameras and may further identify a best or most suitable object for performing a measurement of relative humidity.For example, in a hypothetical case where two cameras are used to scan the environment and a suitable object is detected by both cameras, it can be further determined which object is best suited for performing a relative humidity test. An object that is better suited than another might include, among other things, an object that is larger than another object, an object with a lower surface roughness than another object, an object that is more stationary relative to the vehicle than another object, and so on.

[0104] If, at 710, one or more suitable objects for performing a relative humidity estimation are detected by the one or more cameras, procedure 700 may accordingly proceed to 715. At 715, procedure 700 may involve specifying the position of the suitable object relative to the vehicle. For example, specifying the position of the suitable object relative to the vehicle may include specifying a position toward which the camera was pointed at the time the suitable object was imaged and determining the object's position as a function of the direction in which the camera was pointed. In some examples, one or more camera sensors (e.g., 187) may be used to send signals to the controller indicating the position of the one or more cameras.The control system can be configured to process information about the camera position, and based on a specification of the camera position, a position of an identified suitable object relative to the vehicle can be specified.

[0105] Further on at 720, procedure 700 may include specifying whether a vehicle is equipped with an ultrasonic sensor positioned to detect the identified suitable object for performing a relative humidity measurement. For example, if the vehicle is equipped with a large number of ultrasonic sensors, the position of one or more of these sensors may not be optimal for determining relative humidity based on the position of the identified suitable object. Accordingly, those ultrasonic sensors that are not optimally positioned may be excluded from performing a relative humidity measurement.In other words, at 720, it can be determined which of a multitude of vehicle ultrasonic sensors is optimally positioned to perform a measurement of relative humidity based on the position of the identified suitable object. If at 720 none of the available ultrasonic sensors is optimally positioned to perform a measurement of relative humidity based on the position of the identified suitable object in relation to the vehicle, procedure 700 can revert to 705 and may involve continuing to scan the area around the vehicle for suitable objects.In such an example, the identified suitable object for which an ultrasonic sensor was not available can be excluded from further analysis, so that only other suitable objects can be specified in order to identify a suitable object for which an ultrasonic sensor is optimally positioned to perform a measurement of the relative humidity.

[0106] In some examples, procedure 720 may further specify whether the identified optimal ultrasonic sensor is functioning as desired. For example, if it is determined that an ultrasonic sensor is optimal for detecting a particular identified suitable object, but this ultrasonic sensor is not functioning as desired, procedure 720 may also return to step 705 and may involve continuing the search for suitable objects using available cameras on the vehicle. In some examples, it may be specified that a particular ultrasonic sensor will not function as desired if it is contaminated. A contaminated ultrasonic sensor may be identified, for example, based on the amplitude and distance of a reflected signal.For example, a transmitted signal whose path falls below an expected distance before being reflected back to be received by the sensor may indicate a dirty ultrasonic sensor. Other examples of an ultrasonic sensor not functioning as intended may include any indication that the ultrasonic sensor's function is impaired. Illustrative examples may include an ultrasonic sensor with faulty wiring, worn components, etc. If, for example, it is indicated at 720 that the optimal ultrasonic sensor for detecting a particular suitable object is not functioning as intended, the cameras may accordingly further be used to identify a suitable object for conducting a relative humidity test for which an optimal humidity sensor is present on the vehicle, and where the optimal humidity sensor is functioning as intended.In some of the examples discussed above, more than one suitable object may have been specified in step 710. If it is indicated that a particular ultrasonic sensor is not functioning as desired, such an example may further indicate whether another ultrasonic sensor can be used to perform a measurement of the relative humidity on the other (e.g., one or more) suitable object(s). In such an example, if it is indicated that another ultrasonic sensor is optimally positioned to perform a measurement of the relative humidity on another identified suitable object, and if it is further indicated that such an ultrasonic sensor is functioning as desired, the controller may determine that the ultrasonic sensor functioning as desired is used to detect the specified suitable object.

[0107] In response to a statement that a particular vehicle ultrasonic sensor is optimally configured to perform a relative humidity measurement based on the position of an identified suitable object, the suitable object being identified by one or more in-vehicle cameras, procedure 700 may accordingly proceed to step 725 at step 720. At step 725, procedure 700 may involve performing the relative humidity measurement as described above with reference to the Fig. The procedures shown in sections 4-6 are described. Procedure 700 can then be terminated.

[0108] As described above, certain conditions can trigger a humidity measurement. Furthermore, in some examples it may be preferable to perform a humidity measurement using an ultrasonic sensor, whereas in other examples it may be preferable to perform a humidity measurement using an alternative approach, such as by using a broadband lambda (universal exhaust gas oxygen - UEGO) probe. Such an example may involve conditions in which a vehicle is in operation and one or more in-vehicle cameras do not indicate any objects that are stationary with respect to the vehicle (e.g., no other vehicles traveling at substantially the same speed and in substantially the same direction).In another example, optimal conditions for measuring humidity using a UEGO probe may exist, such as during a deceleration fuel shut-off (DFSO) event. In such a case, it may be preferable to estimate the relative humidity via the UEGO probe, as described in more detail below. By enabling humidity measurements based on vehicle operating conditions, reliable humidity readings can be obtained when it is desirable to have them.

[0109] With reference to Fig. Figure 8 shows a schematic view of an embodiment of an exhaust gas lambda sensor, such as the UEGO sensor 800, configured to measure the concentration of oxygen (O2) in an exhaust gas stream under fuel supply conditions. In one example, the UEGO sensor 800 is an embodiment of the UEGO sensor 126 from Fig. 1. However, it is understood that the sensor is made of Fig. 8 alternatively, it can represent an intake oxygen sensor, such as sensor 172 from Fig. 1. The exhaust gas lambda sensor can also be used during no-fuel conditions to estimate ambient humidity. No-fuel conditions can include engine operating conditions where the fuel supply is interrupted, but the engine continues to rotate and at least one intake and one exhaust valve are operating; such as a fuel cut-off shutdown (DFSO) event. Thus, air can flow through one or more of the cylinders, but no fuel is injected into the cylinders. Under no-fuel conditions, no combustion takes place, and ambient air can move through the cylinder from the intake port to the exhaust port. In this way, a sensor, such as an exhaust gas lambda sensor, can receive ambient air and estimate the ambient humidity. In yet other examples, an oxygen sensor located in the intake air duct (such as oxygen sensor 172 in Fig. 1), and / or a special humidity sensor can be used to estimate the ambient humidity under suitable conditions.

[0110] The Sensor 800 comprises a multitude of layers of one or more ceramic materials arranged in a stacked configuration. In the embodiment made of Fig. Figure 8 shows five ceramic layers as layers 801, 802, 803, 804, and 805. These layers comprise one or more layers of a solid electrolyte capable of conducting ionic oxygen. Examples of suitable solid electrolytes include, among others, zirconium oxide-based materials. In some embodiments, such as the one shown in Fig. As shown in Figure 8, a heating device 807 can also be arranged in thermal communication with the layers to increase the ionic conductivity of the layers. While the UEGO probe 800 shown is formed from five ceramic layers, it is understood that the UEGO probe can include other suitable numbers of ceramic layers.

[0111] Layer 802 contains a material or materials that create a diffusion path 810. The diffusion path 810 is configured to introduce exhaust gases into a first inner cavity 822 via diffusion. The diffusion path 810 can be configured to allow one or more components of the exhaust gases, including a desired analyte (e.g., O2), to diffuse into the inner cavity 822 at a more limiting rate than the rate at which the analyte can be pumped in or out by pumping the electrode pair 812 and 814. This allows a stoichiometric amount of O2 to be obtained in the first inner cavity 822.

[0112] The sensor 800 further includes a second inner cavity 824 within layer 804, which is separated from the first inner cavity 822 by layer 803. The second inner cavity 824 is configured to maintain a constant oxygen partial pressure according to a stoichiometric condition; for example, the amount of oxygen present in the second inner cavity 824 is equal to that which the exhaust gas would have if the air-fuel ratio were stoichiometric. The oxygen concentration in the second inner cavity 824 is controlled by the pump current I. cp kept constant. The second inner cavity 824 can be referred to here as the reference cell.

[0113] A pair of measuring electrodes 816 and 818 is arranged in communication with the first inner cavity 822 and the reference cell 824. The measuring electrode pair 816 and 818 detects a concentration gradient that can develop between the first inner cavity 822 and the reference cell 824 due to an oxygen concentration in the exhaust gas that exceeds or falls below the stoichiometric amount.

[0114] The pair of pump electrodes 812 and 814 is arranged in communication with the inner cavity 822 and is configured to electrochemically pump a selected gas component (e.g., O2) from the inner cavity 822 through the layer 801 and out of the sensor 800. Alternatively, the pair of pump electrodes 812 and 814 can be configured to electrochemically pump a selected gas through the layer 801 and into the inner cavity 822. The pump electrode pair 812 and 814 can be referred to here as an O2 pump cell. The electrodes 812, 814, 816, and 818 can be made of various suitable materials. In some embodiments, the electrodes 812, 814, 816, and 818 can be made at least partially of a material that catalyzes the splitting of molecular oxygen. Examples of such materials include electrodes containing platinum and / or gold.

[0115] The process of electrochemically pumping oxygen from or into the inner cavity 822 involves applying an electric current I p to the entire pump electrode pair 812 and 814. The pump current I p The flow applied to the O2 pump cells pumps oxygen into or out of the first inner cavity 822 to maintain a stoichiometric amount of oxygen in the cavity pump cell. The pump current I p is proportional to the oxygen concentration in the exhaust gas. Thus, a lean mixture causes oxygen to be pumped out of the inner cavity 822, and a rich mixture causes oxygen to be pumped into the inner cavity 822.

[0116] A tax system (in Fig. (8 not shown) generates the pump voltage signal V p depending on the intensity of the pump current I p, which is required to maintain a stoichiometric quantity within the first inner cavity 822.

[0117] It is understood that the oxygen sensor described here is merely one embodiment of a UEGO probe (or an intake manifold oxygen sensor) and that other embodiments of intake or exhaust oxygen sensors may have additional and / or alternative features and / or designs. As briefly discussed above and described in more detail below, under certain conditions it may be preferable to obtain humidity measurements via a UEGO probe or an intake manifold sensor, while under other conditions it may be preferable to obtain humidity measurements via an ultrasonic sensor.

[0118] With reference to Fig. Section 9 presents an exemplary high-level method 900 for performing an opportunistic humidity measurement. Specifically, humidity can be determined in response to the fulfillment of conditions for a humidity determination process, either via an oxygen sensor or by using an ultrasonic sensor. Method 900 is described with reference to the methods described here and in the Fig. 1-2 and Fig. 8 systems shown and with reference to those described here and in the Fig. The methods described in sections 4-7 are explained, although it is understood that similar methods can be applied to other systems without deviating from the scope of this disclosure. Method 900 can be implemented by a controller such as controller 12 in Fig. 1, and can be stored on the controller as executable instructions in non-volatile memory. Instructions for performing procedure 900 and the other procedures contained herein can be executed by the controller based on instructions stored in a memory of the controller and in conjunction with signals from sensors of the engine system, such as those referred to above. Fig. 1 and Fig. The 8 described sensors can be received. The control unit can use fuel system actuators, such as ultrasonic sensor(s) (e.g. 185), camera(s) (e.g. 186), oxygen sensor(s) (e.g. 126), etc., according to the following procedure.

[0119] Procedure 900 begins at 902 and may involve estimating and / or measuring current vehicle operating parameters. Parameters that may be determined include, for example, engine load, engine speed, vehicle speed, manifold vacuum, throttle position, ignition timing, EGR flow, exhaust pressure, air-fuel ratio in the exhaust, assisted or fully automatic parking maneuvers, etc.

[0120] Further, at 905, procedure 900 may include specifying whether conditions for performing a humidity determination operation are met. As discussed above, conditions that trigger a humidity measurement may include a change in ambient temperature exceeding an ambient temperature threshold and / or a change in ambient pressure exceeding an ambient pressure, the change in temperature and / or pressure being relative to a previous (e.g., the last or immediately preceding) humidity measurement. For example, the ambient temperature may be directly estimated as the outside air temperature (OAT) from an OAT sensor located on the exterior of the vehicle.In another example, the ambient temperature can be derived based on an air charge temperature (ACT) or intake air temperature (IAT), as measured by an IAT sensor coupled to an engine intake port. The ambient pressure can be estimated based on the output of an atmospheric pressure (BP) sensor coupled to the intake port. Instead of an absolute change in temperature or pressure differential, some examples can determine whether the temperature or pressure has changed by more than a threshold change in percent (%), where the threshold change in percent can be set based on the absolute ambient temperature or absolute ambient pressure.

[0121] In another example, conditions for determining humidity that are met may also include a threshold value for the time of engine operation or the distance of vehicle movement that exceeds a threshold interval since the last measurement of humidity.

[0122] Other examples where the conditions for determining humidity may be met include the activation of windshield wipers, a change in weather conditions as indicated by GPS and linked to the internet, or any other indication that the ambient humidity has changed since the last humidity measurement.

[0123] If procedure 905 indicates that the conditions for determining humidity are not met, it may proceed to 910. At 910, procedure 900 may involve continuing to adjust vehicle operating parameters based on the last obtained humidity measurement. For example, the last obtained humidity measurement may include a measurement taken using an exhaust gas lambda sensor or an ultrasonic sensor. However, if procedure 905 indicates that the conditions for determining humidity are met, it may proceed to 915. At 915, procedure 900 may include specifying whether the conditions for determining humidity are met, either via intake air or exhaust air oxygen sensors.

[0124] Conditions met for determining humidity using an exhaust gas lambda sensor (e.g., UEGO) may include a no-fuel-supply engine condition, such as a fuel cut-off shutdown (DFSO) event, where estimating ambient humidity may involve switching between applying the first and second voltages to the exhaust gas sensor and generating an ambient humidity reading based on sensor outputs at the first and second voltages, as described above with reference to Fig. 8 described.

[0125] Alternatively, conditions that are met for determining humidity by using an intake oxygen sensor may include conditions where all boost pressure, exhaust gas recirculation (EGR), canister purging, and crankcase ventilation are disabled, and where applying the first and second voltages to the intake oxygen sensor can allow an indication of ambient humidity based on the sensor output at the first and second voltages, as described above with reference to Fig. 8 described.

[0126] If, at 915, it is stated that conditions for using intake and exhaust oxygen sensor(s) for estimating humidity are met, procedure 900 may proceed to 920. At 920, procedure 900 may include determining humidity via the intake or exhaust oxygen sensor.

[0127] When an exhaust gas temperature sensor (UEGO) is used to measure humidity, it may be advisable to wait a specified duration from fuel cutoff until the exhaust gas is substantially free of hydrocarbons from combustion in the engine before starting humidity measurements. For example, residual gases from one or more previous combustion cycles may remain in the exhaust for several cycles after fuel supply is cut off, and the gas vented from the room may contain more than ambient air for a period after fuel injection shutoff. In some examples, the duration since fuel cutoff might be a time elapsed since the fuel cutoff. In other examples, the duration since fuel cutoff might be, for instance, a number of engine cycles since the fuel cutoff.

[0128] To measure humidity, the sensor (intake sensor or exhaust gas lambda sensor) modulates the reference voltage of the entire pump cell between a first and a second voltage. Initially, a lower pump voltage can be applied. As a non-restrictive example, the first voltage could be 450 mV. At 450 mV, for instance, the pump current might indicate a significant amount of oxygen in the duct. At this voltage, water molecules can remain intact, thus not contributing to the total oxygen in the system. Next, a higher pump voltage can be applied. As a non-restrictive example, the second voltage could be 950 mV. At the higher voltage, water molecules can be split.The second voltage is higher than the first voltage, with the second voltage splitting water molecules while the first voltage does not. The sensor outputs include a first pump current generated in response to the application of the first voltage and a second pump current generated in response to the application of the second voltage. Once the water molecules are split due to the second voltage, the total oxygen concentration increases. The pump current represents the amount of oxygen in the channel plus the added amount of oxygen from split water molecules. For example, the first voltage could be a voltage at which a concentration of oxygen can be determined, while the second voltage could be a voltage at which water molecules can be split, thus enabling the estimation of humidity.

[0129] Accordingly, the next step is to determine the change in pump current during voltage modulation. An estimate of the ambient humidity can be derived from the difference between the first and second pump currents generated when the first and second voltages are applied, respectively. The difference (delta) of the pump current at the first reference voltage and the pump current at the second reference voltage can be determined. This delta pump current can be averaged over the duration of the DFSO condition (or any other condition as described above) to determine the ambient humidity. Once the mean change in pump current has been determined, an estimate of the ambient humidity can be calculated.

[0130] After estimating the ambient humidity at 920, procedure 900 can proceed to 925. At 925, procedure 900 may involve adjusting vehicle operating parameters based on the latest humidity measurement. As non-restrictive examples, adjusting vehicle operating parameters may involve adjusting one or more of an exhaust gas recirculation measure, a measure of ignition advance or retard, a limit ignition value, and an estimate of the fuel octane number. For example, an increase in the water concentration of the air surrounding the vehicle may dilute a charge mixture supplied to a combustion chamber of the engine. If one or more operating parameters are not adjusted in response to the increase in humidity, engine power and fuel efficiency may decrease, and emissions may increase; thus, the overall efficiency of the engine may be reduced.In some embodiments, only one parameter can be adjusted in response to humidity. In other embodiments, any combination or subcombination of these operating parameters can be adjusted in response to measured fluctuations in ambient humidity.

[0131] In one embodiment, the amount of EGR can be adjusted based on the measured humidity. For example, an increase in humidity can be detected by the exhaust gas lambda sensor during engine operation without fuel supply (or, in other examples, by the ultrasonic sensor, as discussed below). In response to the increased humidity, the EGR flow to at least one combustion chamber can be reduced during subsequent engine operation with fuel supply. Consequently, engine efficiency can be maintained without worsening NOx emissions.In particular, a vehicle can be at least partially powered by an engine comprising an intake manifold and an exhaust manifold, wherein the engine is operated by the combustion of fuel supplied to the engine, wherein an amount of exhaust gas recirculated to the intake manifold of the engine is controlled while the engine is operating, and wherein the vehicle operating conditions can be adjusted in response to a specification of the relative humidity, wherein the adjustment of the vehicle operating parameters includes one of at least one measure of exhaust gas recirculation supplied to the engine and one measure by which the ignition supplied to the fuel for combustion is delayed or advanced (discussed below).

[0132] In response to fluctuations in humidity, the EGR flow can be increased or decreased in at least one combustion chamber. Therefore, the EGR flow can be increased or decreased in only one combustion chamber, in some combustion chambers, or in all combustion chambers. Furthermore, the magnitude of the change in the EGR flow can be the same for all cylinders, or it can vary depending on the specific operating conditions of each cylinder.

[0133] In another embodiment, the ignition timing can be adjusted in response to humidity measurements. Under at least one condition, for example, the ignition timing in one or more cylinders can be advanced during subsequent engine operation with fuel supply in response to a higher humidity reading. In another example, the ignition timing can be planned to reduce knocking under low humidity conditions (e.g., retarded relative to a peak torque ignition point). If an increase in humidity is detected by the humidity measurement, the ignition timing can be advanced to maintain engine power and operate closer to or at a peak torque ignition point.

[0134] Additionally, the ignition timing can be retarded in response to a reduction in humidity. For example, a decrease in ambient humidity from higher humidity can cause knocking. If the reduction in humidity is detected by an exhaust gas sensor during off-fuel conditions, such as DFSO, the ignition timing can be retarded during subsequent engine operation with fuel supply, thus reducing knocking. It should be noted that the ignition in one or more cylinders may be advanced or retarded during subsequent engine operation with fuel supply. Furthermore, the magnitude of the change in ignition timing may be the same for all cylinders, or one or more cylinders may exhibit varying degrees of advance or retardation.

[0135] In yet another embodiment, the exhaust gas air-fuel ratio can be adjusted in response to the measured ambient humidity during subsequent engine operation with fuel supply. For example, an engine might be operated with a lean air-fuel ratio (relative to stoichiometry) optimized for low humidity. In the event of an increase in humidity, the mixture could become diluted, leading to engine misfire. However, if the increase in humidity is detected by the exhaust gas sensor during no-fuel conditions, the air-fuel ratio can be adjusted so that the engine operates with a less lean air-fuel ratio during subsequent operation with fuel supply.Similarly, the air-fuel ratio can be adjusted to a leaner (than stoichiometry) ratio during subsequent engine operation with fuel injection in response to a measured reduction in ambient humidity. This can reduce conditions such as engine misfires caused by humidity fluctuations. In some cases, an engine can be operated at a stoichiometric or a rich air-fuel ratio. Thus, the air-fuel ratio can be independent of the ambient humidity, and measured fluctuations in humidity will not necessitate an adjustment of the air-fuel ratio.

[0136] In a vehicle that relies on one or more ultrasonic sensors to perform operations, including parking assistance, fully automatic parking functions, or other functions, changes in humidity can also play a role in the operational use of the ultrasonic sensor, as described above. Accordingly, adjusting the vehicle's operating parameters based on the last humidity measurement at 925 may also involve setting a distance detection threshold for the ultrasonic sensor(s). For example, suitable frequencies for performing a distance measurement may be specified, with the appropriate frequencies depending on the humidity level. For instance, certain frequencies may be more attenuated when the percentage of relative humidity increases.Such frequencies can therefore be excluded from distance measurements, for example. Accordingly, a distance detection threshold for individual frequencies can be specified, for example, based on the ambient humidity and stored in a lookup table on the controller. By setting a distance detection threshold for different frequencies of the ultrasonic sensor based on the humidity, the operational use of one or more ultrasonic sensors can be improved. Such a concept is described below with reference to [reference missing]. Fig. 11 and Fig. 12 discussed further.

[0137] Furthermore, in some examples at step 925, tuning detection thresholds can be dynamically adjusted in response to the humidity reading. Setting the tuning detection thresholds can involve adjusting a voltage level (e.g., the voltage response from the ultrasonic sensor) that indicates an object relative to noise. Specifically, if the tuning detection thresholds are set too high, the sensor may be blind to many objects. Conversely, if the tuning detection thresholds are set too low, the sensor may be overly sensitive to noise, potentially indicating an object where none exists.Since humidity can affect the attenuation of ultrasonic waves in a frequency-dependent manner, the tuning detection thresholds can be adjusted, once the humidity is known, to account for the change in attenuation due to relative humidity. For example, a tuning detection threshold can be increased (e.g., made more stringent) in response to a specified lower relative humidity (e.g., 20%), whereas the tuning threshold can be decreased (e.g., made less stringent) in response to a specified higher relative humidity (e.g., 90%). These examples are intended to be illustrative and not limiting. Furthermore, the tuning detection thresholds can be set based on a frequency or frequencies selected for object detection.In particular, the tuning detection thresholds can vary depending on the frequency or frequencies selected for object detection, and such tuning detection thresholds can be stored, for example, in a lookup table on the controller, depending on the frequency.

[0138] At 915, procedure 900 may proceed to 930 unless it is specified that conditions for using either the intake oxygen sensors or the exhaust gas lambda probes to determine ambient humidity are met. At 930, procedure 900 may involve determining humidity using one or more ultrasonic sensors, as described in the Fig. 4-7 are discussed in detail. Since the procedure for determining humidity using ultrasonic sensors has already been discussed, it will not be repeated here for the sake of brevity. However, it goes without saying that any aspects of the procedure described in the Fig. The methods shown in 4-7 can be used to determine the ambient humidity by using ultrasonic sensor(s).

[0139] As an example, in some cases one or more cameras can be used to identify suitable objects for humidity measurements via an ultrasonic sensor, as described above with reference to Fig. 7 described. However, cases may arise where a vehicle cannot be equipped with a camera. In such an exemplary case, one or more ultrasonic sensors can be systematically used with reference to the above. Fig. The methods described in sections 4-6 can be tested to determine the ambient humidity. In other words, the detection of the presence of an object can be performed by one or more of the following: the ultrasonic sensor positioned on the vehicle and one or more in-vehicle cameras. Although in Fig. Unless expressly stated in Section 9, it is understood that if conditions for the use of intake or exhaust oxygen sensors to determine ambient humidity in step 915 are not met and if subsequent attempts to determine ambient humidity via ultrasonic sensor(s) are unsuccessful (e.g., suitable objects not identified via cameras and / or ultrasonic sensors), procedure 900 may be delayed until suitable conditions for determining ambient humidity are specified.

[0140] Further to step 925, procedure 900 may involve adjusting the vehicle operating parameters based on the last humidity measurement as determined by the ultrasonic sensor(s). Since a detailed description of step 925 is given above, the majority of possible adjustments to the vehicle operating parameters depending on a specific change in humidity are not repeated here for the sake of brevity. However, it is understood that any of the vehicle operating parameters that are adjusted in response to a humidity measurement taken by the intake or exhaust oxygen sensor(s) may also be adjusted in response to a humidity measurement taken by one or more ultrasonic sensors.

[0141] In this way, changes in ambient conditions (e.g., temperature, pressure, etc.) that affect humidity can be used to trigger a humidity measurement. This measurement can be performed in response to vehicle operating conditions, thus increasing the likelihood of obtaining an accurate reading of the ambient humidity. In other words, a suitable procedure for determining humidity by determining vehicle operating conditions in response to a request for a humidity measurement, as described in [reference to relevant document / reference], can be [context missing]. Fig. The procedures shown in 900 are specified and carried out.

[0142] In another example, an ultrasonic sensor can be used to adjust vehicle operating conditions, and knowledge of the percentage relative humidity can further be advantageous for adjusting these conditions. In such an example, an ultrasonic sensor can be used to determine the humidity, and the vehicle operations can then be adjusted based on the humidity measurement. In particular, carbon particles are a byproduct of diesel fuel combustion, known as soot. Emission control devices, such as diesel particulate filters (DPFs) (e.g., 72), reduce soot emissions from an engine by trapping soot particles. Filter regeneration can be performed periodically when the filter becomes saturated with soot.For example, the filter temperature can be raised to a predetermined level to oxidize or burn off the accumulated particulate matter. In some cases, regeneration can be achieved by injecting additional fuel into the exhaust stream. In other cases, regeneration can be achieved by modifying the engine operation to increase the exhaust temperature. In still other cases, a heating device (e.g., 75) can be used to selectively heat the DPF. Filter regeneration can occur during normal driving conditions or can be initiated at other times, such as when a vehicle is stopped at the driver's request, during vehicle maintenance, etc.Since regeneration involves increasing the exhaust gas temperature, it may be advantageous to perform such a process only when it is specified that an object is located at a certain distance from the exhaust.

[0143] However, one factor that can contribute to a desired distance between an object and a vehicle exhaust during a DPF regeneration event is the percentage of relative humidity. For example, heat transfer through air can depend on the ambient temperature and humidity. Therefore, if both the ambient temperature and humidity are known, threshold values ​​for the distance between an object and an exhaust can be set accordingly for a given DPF regeneration event, as discussed in more detail below.

[0144] Referring to FG. 10, diagram 1000 is shown, illustrating the relationship between temperature, humidity, and the thermal conductivity of air (in watts per meter Kelvin). Specifically, the x-axis represents the air temperature in the range of 0 °C to 100 °C, and the y-axis represents the thermal conductivity of air in the range of 0.024 W / m*K to 0.033 W / m*K. In addition, various curves illustrating the percentage of humidity are shown.Specifically, curve 1005 illustrates 0% humidity, curve 1010 illustrates 10% humidity, curve 1015 illustrates 20% humidity, curve 1020 illustrates 30% humidity, curve 1025 illustrates 40% humidity, curve 1030 illustrates 50% humidity, curve 1035 illustrates 60% humidity, curve 1040 illustrates 70% humidity, curve 1045 illustrates 80% humidity, curve 1050 illustrates 90% humidity, and curve 1055 illustrates 100% humidity. As illustrated, thermal conductivity depends on temperature and humidity. For example, the thermal conductivity of air increases from 0°C to approximately 60°C at 100% humidity. However, if the temperature is increased further, the thermal conductivity decreases.Since thermal conductivity depends on temperature and ambient humidity, the thermal conductivity of air can be determined and a threshold value for a distance between an exhaust and an identified object can be set accordingly if both variables (temperature and ambient humidity) are known, as shown below according to the formula in . Fig. The procedures shown in section 11 are described in detail.

[0145] With reference to Fig. Figure 11 presents an exemplary high-level procedure for carrying out a DPF regeneration process. In response to conditions that are favorable for DPF regeneration, and where it is specified that a vehicle speed falls below a threshold speed, objects near a vehicle exhaust and their distance from the exhaust can be determined, and the ambient humidity and temperature can be specified. Based on the specified distance of objects near the exhaust, and further based on the specified ambient humidity and temperature, a distance threshold can be set such that if an object is positioned at a distance from the exhaust that is less than the set threshold distance, the filter regeneration can be postponed until more favorable conditions for DPF regeneration are met. In other words, the procedure described in Figure 11 involves... Fig. 11. Methods illustrated: Regenerating a particulate filter coupled to the underbody of the motor vehicle by causing the combustion of particles deposited in the particulate filter, resulting in hot gases exiting from the rear of the motor vehicle; selecting the selected sensor based on a transmission path of the selected sensor that overlaps with at least part of the hot gases exiting from the rear of the motor vehicle; and postponing or aborting the regeneration based on the presence of an object within a predetermined distance of the hot gases exiting from the rear of the motor vehicle.As an example, the procedure may further include: measuring an air temperature near the point where the hot gases exit the rear of the motor vehicle; determining the thermal conductivity of air based, at least in part, on the relative humidity and air temperature; and setting a distance threshold for the regeneration process, wherein setting the distance threshold involves lowering the distance threshold when the thermal conductivity decreases and raising the distance threshold when the thermal conductivity increases.

[0146] Procedure 1100 is carried out with reference to the procedures described here and in Fig. The systems shown in section 1 are described, although it is understood that similar methods can be applied to other systems without deviating from the scope of this disclosure. Method 1100 can be applied to a controller such as controller 12 in Fig. 1, and can be carried out and may be stored on the controller as executable instructions in non-volatile memory. Instructions for carrying out procedure 1100 and the other procedures contained herein may be executed by the controller based on instructions stored in a memory of the controller and in conjunction with signals from sensors of the engine system, such as those referred to above. Fig. The controller can receive data from the sensors described in section 1. The controller can utilize vehicle system actuators, such as ultrasonic sensor(s) (e.g., 185), camera(s), a hydrocarbon (HC) reducing agent supply system (e.g., 74), fuel injection device(s) (e.g., 66), a DPF heater (e.g., 75), etc., according to the following procedure.

[0147] Procedure 1100 begins at 1105 and may involve determining current vehicle operating parameters. Operating conditions can be estimated, measured, and / or derived, and may include one or more vehicle conditions, such as vehicle speed, vehicle position, etc.; various engine conditions, such as engine status, engine load, engine speed, air-fuel ratio, etc.; various fuel system conditions, such as fuel level, fuel type, fuel temperature, etc.; and various evaporative emission system conditions, such as fuel vapor filter load, fuel tank pressure, etc.

[0148] Further down at 1110, procedure 1100 may involve determining the load state of a diesel particulate filter (DPF) (e.g., 72). Various strategies can be used to determine a DPF load state to indicate whether the DPF filter needs regeneration. For example, a threshold pressure differential across the DPF may indicate that a DPF load state exceeds a threshold load state. In such an example, a pressure sensor (e.g., 80) may be positioned upstream of the DPF, and another pressure sensor (e.g., 82) may be positioned downstream of the DPF so that a pressure differential across the DPF can be communicated to the vehicle control unit. In other examples, a DPF load state may be derived or estimated based on the number of kilometers the vehicle has traveled since a previous DPF regeneration.In yet another example, the load state of the DPF can be derived or estimated as a function of the engine operating time since a previous DPF regeneration process. Such examples are intended to illustrate and are in no way limiting. For instance, other known methods for indicating the DPF load state can be used without deviating from the scope of this disclosure.

[0149] Further down at step 1115, it can be specified whether conditions for performing a DPF regeneration process are met. For example, if it is indicated that a DPF load state exceeds the predetermined threshold, as discussed above with reference to step 1110 of procedure 1100, it can be stated that the DPF regeneration conditions are met. However, if the DPF regeneration conditions are not met, procedure 1100 can proceed to step 1120. At step 1120, procedure 1100 can involve maintaining the current vehicle operating parameters. For example, at step 1120, procedure 1100 can involve continuing non-DPF regeneration engine operation, and the DPF can continue to collect soot and monitor the DPF load state.

[0150] At 1115, if it is indicated that the regeneration conditions are met, the procedure can proceed from 1100 to 1125 and may include an indication of whether the vehicle is traveling above a predetermined speed threshold. For example, the predetermined speed threshold could be a specific speed at which outside ambient air convection is sufficient to reduce exhaust outlet temperatures below a certain threshold. In such an example, potential issues with objects positioned near the exhaust can be disregarded, as exhaust temperatures are unlikely to pose a significant problem for reducing exhaust outlet temperatures due to airflow.Furthermore, the probability of an object being positioned near the exhaust may be additionally low, so it is not a major concern if the vehicle is traveling at a speed exceeding the predetermined speed threshold. Therefore, if at 1125 it is indicated that the vehicle is traveling above the predetermined speed threshold, the procedure may proceed from 1100 to 1130 and may involve performing the regeneration process without determining whether an object is within a predetermined distance of the hot gases exiting the rear of the vehicle.

[0151] Regenerating the DPF at 1130 can involve adjusting engine operating parameters to allow DPF regeneration. For example, the engine control unit may contain stored instructions for DPF regeneration. Examples include operating a heating device (e.g., 75) connected to the DPF or increasing the engine exhaust temperature (e.g., by running rich or directly injecting fuel into the exhaust), where the increased exhaust temperature can raise the DPF temperature to convert soot in the DPF to ash.

[0152] The DPF regeneration at 1130 can further include determining whether the soot load falls below a predetermined threshold. For example, the predetermined threshold may include a lower threshold below which DPF regeneration can be terminated. Regeneration can, for instance, be continued until the soot load is below the predetermined threshold. In such an example, a DPF load state can be indicated, for instance, by a pressure differential across the DPF. However, as discussed above, other methods for indicating the DPF load state can also be used without deviating from the scope of this disclosure.

[0153] When the DPF load is sufficiently low (e.g., below the predetermined threshold), DPF regeneration can be terminated. Termination can involve canceling any vehicle operating parameter that contributes to heating the filter. For example, if fuel was being injected into the exhaust, such injection can be stopped. In another example, if the fuel injection to the engine is set to a rich mixture, such fuel injection can be similarly canceled, and fuel injection can return to standard operation, which may include an operational state prior to the DPF regeneration process. In yet other examples, if a heating device was activated to regenerate the DPF, the heating device can be deactivated. In all such examples, the operations can be controlled by a vehicle control unit (e.g.,12) are controlled, with signals being sent to the various actuators (e.g. fuel injection device, heating device) to terminate the regeneration operation.

[0154] Further down at 1135, procedure 1100 can include updating vehicle operating conditions. For example, a DPF load state can be updated based on the last DPF regeneration. Such updated information can be stored on the control unit. Additionally, a regeneration schedule stored on the control unit can be updated based on the regeneration process and the subsequent DPF load state. In a case where, for example, a regeneration schedule involves requesting a regeneration after a predetermined number of miles driven or a predetermined number of hours of engine operation, such numbers can be reset on the control unit to effectively request a future regeneration. Procedure 1100 can then be terminated.

[0155] At 1125, unless it is specified that the vehicle is traveling above the predetermined threshold speed, the procedure may transition from 1100 to 1140. At 1140, the procedure may involve detecting objects near the vehicle's exhaust and may further involve determining the relative humidity, if possible. For example, if the vehicle is equipped with one or more rear-facing cameras, the controller may order these cameras to scan an area at the rear of the vehicle. Such an exemplary procedure for using available in-vehicle camera(s) to detect objects, with the relative humidity being determined in response to the detection of suitable objects, is described above in the Fig. The procedures illustrated in Figures 7 and 4-6 are shown. In a case where determining the humidity is possible, it is understood that the ambient temperature can also be determined, as above with reference to the Fig. 4-6 discussed. It is also understood that an ultrasonic sensor can be selected to determine the relative humidity, wherein the ultrasonic sensor is selected from a variety of sensors based on the selected transmission and reception path of the sensor, which overlaps with at least part of the hot gases exiting from the rear of the motor vehicle.

[0156] A detailed description of how one or more cameras can be used to detect objects that may be located near the exhaust is not repeated here, as it has been discussed above. In short, the control system can command the one or more cameras to search for objects at the rear of the vehicle that may be in close proximity to the exhaust. If such objects are detected, it can further be specified, as discussed above, whether the objects appear stationary relative to the vehicle, whether the vehicle is moving, or whether it is parked. For example, multiple camera images can be obtained, and if it is specified that the objects change position, size, or shape between images, it can be determined that such an identified object cannot be stationary relative to the vehicle.In some examples, ultrasonic sensors can be used additionally or alternatively to identify objects and to indicate whether the identified objects appear stationary in relation to the vehicle.

[0157] If potential objects are identified based on the one or more rear-facing cameras (or ultrasonic sensors) that may be stationary relative to the vehicle (e.g., a moving car traveling at the same speed and in the same direction as the car attempting to perform a DPF regeneration), the humidity may further be determined in accordance with the above in the Fig. The methods described in sections 4-6 are used to determine the humidity. As discussed above, it is understood that the ultrasonic sensor can be selected for use in determining the humidity based on the ultrasonic signals that overlap with at least some of the hot gases exiting the rear of the vehicle. Additionally, a temperature sensor located in close proximity to the vehicle's exhaust can be selected for determining the ambient temperature.

[0158] Some examples may involve a vehicle that is not moving but rather stationary (e.g., parked). In some examples, a parked regeneration might involve the driver shifting the vehicle's transmission (not shown) into neutral, applying the parking brake (not shown), pressing and releasing the clutch pedal (not shown), and pressing and holding a regeneration button on the vehicle's dashboard until the engine speed increases, at which point the DPF regeneration process can begin. In such an example, when the regeneration is complete, warning lights on the dashboard may go out, indicating the completion of the regeneration event.While the vehicle is parked, it is likely that one or more rear-facing cameras and / or ultrasonic sensors will detect one or more objects near the exhaust, and an accurate measurement of humidity can be obtained, as above and in accordance with the above with reference to the . Fig. The procedures shown in sections 4-6 are discussed.

[0159] As discussed above, determining the relative humidity can allow for setting (correcting) a distance detection threshold for the ultrasonic sensor used, in order to determine the distance between the vehicle and an object of interest, since humidity can affect the operational use of an ultrasonic sensor. For example, because certain frequencies may be attenuated differently depending on the relative humidity, a distance detection threshold for individual frequencies can be specified based on the determined relative humidity and stored in a lookup table on the controller (e.g., 12). For instance, when high humidity is specified, frequencies in a lower range (20-40 kHz) can be used instead of higher frequencies, thus improving the operational use of the ultrasonic sensor.

[0160] Furthermore, when attempting to detect objects near the vehicle's exhaust, it may be that only one or more ultrasonic sensors configured on the vehicle to detect objects at the rear of the vehicle are used to determine the relative humidity and to detect objects at 1140.

[0161] In some examples, a vehicle may not be equipped with one or more rear-facing cameras. In such an example, one or more ultrasonic sensors positioned at the rear of the vehicle can be instructed to estimate the relative humidity and measure the distance according to the principles described above and in the Fig. The procedures illustrated in Figures 4-6 can be carried out. For example, ultrasonic sensors can be used instead of cameras to detect objects near the exhaust. Ultrasonic sensors can also be used to detect objects that appear stationary relative to the vehicle (e.g., over the same travel time between two or more ultrasonic frequencies), allowing a humidity measurement to be obtained and thus an accurate distance measurement to be performed.

[0162] Continuing at 1145, the procedure can proceed from 1100 to 1130 if no objects were detected, and may include DPF regeneration as described in detail above. However, if objects were detected and, where possible, an estimate of the humidity was determined, the procedure can proceed from 1100 to 1150.

[0163] As discussed above, the thermal conductivity of air can depend on the air temperature and relative humidity. Accordingly, procedure 1100, in response to detected objects and a humidity measurement, can involve measuring the ambient temperature at 1150. As discussed above, the ambient temperature measurement can be performed using an outdoor air temperature (OAT) sensor (e.g., 127). Such an outdoor air temperature reading can be stored, for example, on the controller (e.g., 12). Once an object has been detected and the relative humidity (if possible) and ambient air temperature have been determined, procedure 1100 can proceed to 1155.In procedure 1155, procedure 1100 may involve setting a distance threshold based on the measurement of relative humidity and the determination of the ambient temperature, with the air temperature being measured near the point where hot gases exit the rear of the vehicle. For example, the distance threshold may include a distance above which a DPF regeneration process can be carried out without concern that heat from the exhaust may affect the detected object(s). In a case where the humidity could not be determined, a predetermined distance threshold may be used instead of setting the distance threshold.

[0164] In particular, the thermal conductivity of air can vary depending on humidity and temperature, as shown in Fig. Figure 10 illustrates this. As an example, the thermal conductivity of air at 60 °C and 80% relative humidity (e.g., line 1045) can be approximately 0.0275 W / m*K, whereas the thermal conductivity of air at 90 °C and 80% relative humidity can be approximately 0.026 W / m*K. In other words, thermal conductivity can decrease when the temperature increases from 60 °C to 90 °C and the ambient humidity is 80%. Thus, heat may not be conducted as efficiently in the air when the temperature increases from 60 °C to 90 °C under conditions where the relative humidity is 80%. Accordingly, the procedure 1100 can include setting the distance threshold for the regeneration process, wherein setting the distance threshold includes lowering the distance threshold when the thermal conductivity decreases and raising the distance threshold when the thermal conductivity increases.

[0165] Such conditions are intended to be illustrative; however, it is understood that the distance threshold is based on any measurement of relative humidity and temperature according to the [reference to be added]. Fig. As shown in diagram 10, the distance threshold can be set accordingly. For example, a lookup table can be stored on the controller, containing a value that can be used to set the distance threshold based on the specified relative humidity and temperature. Thus, a value for setting the distance threshold can be easily obtained for each pair of relative humidity and temperature measurements. Most importantly, the accuracy of setting the distance threshold can be increased by using the ultrasonic sensor to detect both the ambient humidity and the distance between the sensor and the specified object, compared to a situation where the ambient humidity is derived from other means (e.g., intake or exhaust oxygen sensors).In particular, obtaining the humidity reading using ultrasonic sensors immediately before setting the distance threshold can be advantageous in that the humidity can be precisely determined specifically for the purpose of setting the distance threshold, as the humidity can be localized. Since the ultrasonic sensor used to determine the humidity can be selected based on the fact that at least part of its transmission and reception path overlaps with the hot gases exiting the rear of the vehicle, the humidity readings can further reflect the humidity conditions near the rear of the vehicle, where hot gases are expected during the DPF regeneration process.

[0166] After setting the distance threshold based on the specified ambient humidity and temperature at step 1155, the procedure can proceed from step 1100 to step 1160. At step 1160, the procedure can include indicating whether the distance between the object of interest and the exhaust is greater or less than the set distance threshold. For example, the ultrasonic sensors can be used to determine the distance of the specified object from the exhaust. If it is indicated that the object is positioned such that the set distance threshold from the exhaust is not exceeded, the procedure can return to step 1125 and may involve continuing to determine whether conditions exist to perform the DPF regeneration process.However, if it is indicated that the object is positioned in such a way that the set distance threshold away from the exhaust is exceeded, the procedure may change from 1100 to 1130 and may include regenerating the DPF filter, as described in detail above.

[0167] Although in Fig. Although not explicitly illustrated in section 11, it is understood that during DPF regeneration, one or more of the vehicle's internal cameras and ultrasonic sensors can be used to ensure that an object does not cross the set distance threshold while the DPF regeneration is taking place. For example, the controller can instruct one or more cameras to record images during the DPF regeneration event and process the images, as discussed above, using object detection algorithms stored on the controller, so that it can be indicated whether objects appear to have moved during the regeneration event, and, more importantly, whether the objects appear to have moved to a position that falls below the set distance threshold away from the vehicle's exhaust.Such examples might include determining the distance between the exhaust and the identified objects using the ultrasonic sensor(s). In a case where one or more cameras are not present in the vehicle, the ultrasonic sensor(s) can be used solely to determine the distance of the identified object(s) from the vehicle's exhaust. In an example scenario where it is determined that an object or objects are positioned below the set distance threshold, the regeneration process can be abruptly terminated or interrupted. Such an action can be performed, for example, by the control unit.By monitoring the DPF regeneration event using one or more cameras and one or more ultrasonic sensors, the presence of an object at a position below the set distance threshold can be easily identified, allowing the DPF regeneration event to be interrupted. In other words, Method 1100 may involve: initiating the regeneration process in response to the object being positioned at a greater distance than the threshold distance; monitoring the object and an area near the rear of the vehicle using the one or more cameras during the regeneration process; and terminating the regeneration process if it is detected that the object or objects are below the threshold distance during the regeneration process.

[0168] As discussed above, a distance detection threshold for ultrasonic sensors can be set by specifying the ambient temperature and humidity, as well as two noise factors, to improve the sensor's operational performance. However, it may also be desirable to select optimal frequencies for specific distance measurements, provided that it is specified whether an object of interest can be located at a short distance (short range), a medium distance (medium range), or a long distance (long range) from the ultrasonic sensor. By using an optimal frequency for a specific distance measurement, for which a distance detection threshold has been set, the operational performance of the ultrasonic sensor can be further enhanced.In some examples, the optimal frequency may depend on the set distance detection threshold and the desired operational use of the sensor. In some examples, a large number of images of an environment near the vehicle may be captured by one or more in-vehicle cameras, with the desired operational use of the sensor being determined, at least in part, by these one or more cameras, as discussed in more detail below.

[0169] With reference to Fig. Figure 12 presents an exemplary high-level procedure for setting a distance detection threshold for an ultrasonic sensor and further for determining an optimal frequency(ies) for distance measurements. Specifically, two noise factors for ultrasonic distance measurements can be controlled by determining the ambient humidity and ambient temperature, thus enabling the setting of a distance detection threshold. Depending on the set distance detection threshold, an optimal frequency(ies) can be selected for subsequent distance measurement. In some examples, the same ultrasonic sensor used to determine the humidity can subsequently be used for distance measurement. In other examples, however, the sensor used to determine the relative humidity may be a different sensor.

[0170] Procedure 1200 is carried out with reference to the procedures described here and in Fig. The systems shown in Figure 1 are described, although it is understood that similar methods can be applied to other systems without deviating from the scope of this disclosure. Method 1200 can be applied to a controller such as controller 12 in Figure 12. Fig. 1, and can be carried out and may be stored on the controller as executable instructions in non-volatile memory. Instructions for carrying out procedure 1200 and the other procedures contained herein may be executed by the controller based on instructions stored in a memory of the controller and in conjunction with signals from sensors of the engine system, such as those referred to above. Fig. The controller can receive data from the sensors described in section 1. The controller can utilize fuel system and evaporative emission system actuators, such as ultrasonic sensor(s) (e.g., 185), camera(s) (e.g., 186), etc., according to the procedure described below.

[0171] Procedure 1200 begins at 1205 and may include an indication of whether an object of interest has been detected. As above, with reference to Fig. As discussed in section 7, the detection and indication of objects of interest can, in some examples, be carried out using one or more in-vehicle cameras. Since a process for detecting objects using one or more cameras has been thoroughly discussed above, a complete description is not repeated here for the sake of brevity. However, it is understood that the object detection and indication of suitable objects in section 1205 can be determined using one or more cameras, as described above. Fig. 7 is discussed. In some examples, a vehicle may not be equipped with one or more cameras, or the vehicle may be equipped with camera(s) but not necessarily in an optimal position to detect all possible objects positioned around the vehicle. In such an example, one or more ultrasonic sensors may be used additionally or alternatively to detect and indicate potentially suitable objects of interest. In some examples, an object search may be initiated based on the fulfillment of conditions for determining humidity, such as a specified change in ambient temperature or ambient pressure, as described above in step 905 of Procedure 900. In another example, suitable objects may be detected while a vehicle is performing an assisted or fully automated parking maneuver.Such examples are intended to be illustrative and not restrictive.

[0172] If no suitable objects of interest are specified at 1205, procedure 1200 can proceed to 1210 and may involve maintaining current vehicle operating parameters. For example, if the controller has been instructed to search for suitable objects of interest using camera(s) and / or ultrasonic sensor(s), procedure 1200 at 1205 can continue the search for suitable objects of interest.

[0173] If procedure 1200 indicates at 1205 that a suitable object of interest can be identified, procedure 1200 may alternatively proceed to 1215. At 1215, procedure 1200 may involve determining the humidity using an ultrasonic sensor, as described above. In particular, determining the humidity at 1220 may involve determining the ambient temperature, for example, using an OAT sensor (e.g., 127). Furthermore, determining the ambient humidity may additionally involve performing the variable frequency algorithm ( Fig. 5) and the delta damping calculation ( Fig. 6) include. In other words, determining the ambient humidity at 1215 can be determined according to the high-level procedure from Fig. 4. Since the procedure for determining humidity using an ultrasonic sensor has been described in detail above, a thorough explanation is not repeated here for the sake of brevity. It is understood, however, that determining the ambient humidity at 1215 by following the procedure described in Fig. This can be achieved using the methods described in section 4.

[0174] In response to the humidity (and ambient temperature) being determined, procedure 1200 may transition to 1230. At 1230, procedure 1200 may involve setting a distance detection threshold for the ultrasonic sensor used to determine the humidity. For example, the maximum range at which an ultrasonic sensor can detect a target object may be affected by sound attenuation, with a major noise factor related to sound attenuation potentially including ambient humidity. Furthermore, accurately determining the speed of sound can be important for converting the transit time from transmitting to receiving an ultrasonic signal into a distance measurement. Since the speed of sound is affected by ambient temperature, knowledge of the ambient temperature can further enhance the operational applicability of the ultrasonic sensor.Furthermore, an accurate estimate of ambient humidity may require knowledge of the ambient temperature, as discussed above. Accordingly, setting the distance detection threshold at 1230 may be based on the specified humidity and ambient temperature. In some examples, the distance detection threshold may be frequency-dependent, meaning it could differ for various frequencies. For instance, a distance measurement exceeding a certain distance might not be achievable at 100 kHz and 80% relative humidity, but could instead be achieved at 30 kHz due to reduced sound attenuation compared to 100 kHz at 80% humidity. This example is for illustrative purposes only.Accordingly, for example, a distance detection threshold (or thresholds) can be determined at different frequencies for the specified humidity in response to the humidity measurement and stored in a lookup table. In other words, setting the distance detection threshold for the ultrasonic sensor in some examples, in response to a specified relative humidity, may involve specifying suitable frequencies for performing distance measurements depending on the relative humidity value.

[0175] Further on at 1235, the procedure 1200 may include determining the desired operational use of the ultrasonic sensor so that the sensor can be used to perform a distance measurement based on the desired operational use of the sensor. In particular, determining the desired operational use may include determining whether a particular object for which a distance measurement is desired is at a short range (e.g., less than 1 meter), a medium range (e.g., more than 1 meter but less than 2 meters), or a long range (e.g., more than 2 meters). In an example, determining the range at which a particular object is positioned away from the ultrasonic sensor may involve estimating a distance (a range) by using the one or more in-vehicle cameras, if equipped.For example, a rough distance estimate can be easily obtained using the vehicle's onboard cameras, employing object recognition software commonly known in the field and the algorithms that may be stored on the controller. In another example, a rough calculation can be performed by an initial distance determination using the ultrasonic sensor. In such a case, one or more specific frequencies can be transmitted and received by the ultrasonic sensor to perform a rough distance calculation, since the distance to the object is unknown. Such a calculation can involve determining whether the distance between the ultrasonic sensor and the object of interest is short-range, medium-range, or long-range from the sensor.

[0176] Accordingly, determining the desired operational use of ultrasonic sensors can be achieved by retrieving information from a lookup table stored on the controller, for example, the one in 1235. Fig. The 13 lookup tables shown contain them.

[0177] With reference to Fig. Figure 13 presents an exemplary lookup table illustrating an optimal ultrasonic frequency that can be used for distance measurements based on the specified position of the object of interest at short, medium, or long range from the ultrasonic sensor used to perform the distance measurement. As discussed below, the desired frequency(ies) to be used can also be selected depending on the distance detection thresholds set above.

[0178] If the desired distance to an object of interest is specified as being located a short distance from the ultrasonic sensor, then all frequencies that the ultrasonic sensor can transmit (e.g., 20 kHz to 100 kHz) can be used as a theoretical example for distance measurement, since sound attenuation is not a significant factor at short ranges. However, some frequencies may still be more desirable than others based on the distance detection threshold. For short-range distance measurements, the frequency that can be selected will in any case include an optimal frequency at which the piezoelectric crystal of the ultrasonic sensor can operate as designed, since most, if not all, frequencies can provide accurate distance measurements due to the minimal impact of sound attenuation.For example, this frequency could be a known value and stored in the controller. If such a frequency is undesirable due to potential attenuation based on the set distance detection threshold, a lower frequency can be selected.

[0179] As another example, if the desired distance to an object of interest is specified as being at a medium range from the ultrasonic sensor, frequencies in the low to medium range (e.g., 20 kHz to 50-60 kHz) can be selected to perform the distance measurement for increased accuracy. In such an example, frequencies other than those excluded can be selected if the set distance detection threshold excludes any of the possible frequencies from use. For example, attenuation at 60 kHz due to a certain relative humidity might prevent objects 1.5 m away from an ultrasonic sensor from being accurately detected (e.g., distance measurement inaccurate), but other lower frequencies might allow for accurate detection and measurement.Such information can be provided via the lookup table for the configured distance detection, as described above with reference to step 1230 of procedure 1200. In any case, regardless of whether certain frequencies in the short to medium range can be excluded based on the configured distance detection threshold, a frequency can be selected such that the selected frequency is within the range for optimal accuracy and is closest to the optimal frequency at which the sensor can be operated as designed. As discussed above, such an optimal frequency specification can be stored on the controller.

[0180] As yet another example, low-frequency operation (e.g., between 40 kHz and 20 kHz) can be selected for distance measurement to achieve increased accuracy when the desired distance to an object of interest is located at a long range from the ultrasonic sensor. As discussed above, frequencies other than those excluded can be selected if the set distance detection threshold excludes any of the possible frequencies from use. Similarly to what is described above for medium range, regardless of whether certain frequencies are excluded or not, a frequency can be selected such that it falls within the range for the desired operation and is closest to the optimal frequency at which the sensor can operate as designed.

[0181] At step 1235, procedure 1200 can proceed to step 1240 in response to the determination of the desired operational use of the ultrasonic sensor. At step 1240, procedure 1200 can involve performing the distance measurement(s) by transmitting and receiving the ultrasonic wave frequency selected as an optimal frequency in step 1235. As discussed above, the controller can command that an oscillating voltage be sent to the ultrasonic sensor, thereby converting the electrical oscillation into mechanical sound waves that can be transmitted by the ultrasonic sensor. After the sound waves have been reflected by the object of interest, they can be received by the sensor (e.g., receiver), the reception of the sound waves involving the conversion of the mechanical waves back into electrical oscillations that can be evaluated by the controller.A distance measurement can be determined based on the travel time from transmission to reception of the reflected waves. In particular, the distance can be specified, as described above, using the formula d=t*c / 2, where c is the speed of sound and t is the travel time.

[0182] Furthermore, tuning detection thresholds at 1240 can be additionally set in response to the specified humidity. As discussed above, setting the tuning detection thresholds can involve setting a voltage level to indicate an object relative to noise across one or more ultrasonic sensors. The tuning detection thresholds can vary depending on the frequency or frequencies selected for object detection, and such frequency-dependent tuning detection thresholds can, for example, be stored in a lookup table on the controller.

[0183] In some examples, cases may arise where the selected frequency for performing the distance measurement leads to a signal-to-noise problem for one reason or another. For example, the angle of the object of interest may have changed, or the object may have moved from one distance to another, etc. Accordingly, Procedure 1200 may further specify at 1245 whether additional accuracy may be desired. If attenuation or some other environmental influence during the distance measurement has led to a signal-to-noise problem, preventing the obtaining of a desired distance estimate, Procedure 1200 may proceed to 1250. At 1250, Procedure 1200 may involve actions such as varying the ultrasonic frequency in an attempt to obtain improved distance measurements between the ultrasonic sensor and the object of interest.For example, if a specific frequency was selected based on the object being located at a medium range from the sensor, other frequencies can be used next, depending on the determination of the optimal medium range. In some examples, one or more cameras (if the vehicle is equipped with them) can be used to indicate whether the object of interest might have moved (e.g., further away from or closer to the ultrasonic sensor). In still other examples, frequencies outside the selected range can be used in an attempt to increase the accuracy of the distance measurement. For example, if it was predicted that the object of interest would be at a medium range, and thus a frequency of 50 kHz was selected, a lower frequency (e.g., 10 kHz) can be used.30 kHz) can be used next when attempting to reduce attenuation if a good distance estimate has not been obtained. Such examples are illustrative and not intended to be restrictive.

[0184] At 1245, the procedure can continue from 1200 to 1255 and may include indicating the object's distance if additional accuracy is not desired, or in other words, if the signal-to-noise ratio of the transmitted and received ultrasonic wave exceeds a level at which the desired measurement(s) can be obtained. Such a distance determination can, in one example, be stored at least temporarily on the controller. Furthermore, such a distance determination method can be used in some examples to perform an assisted or fully automatic parking maneuver more effectively, as described above with reference to... Fig. 2 described system.

[0185] With reference to Fig. 14 is an exemplary timeline 1400, which involves carrying out an opportunistic procedure to determine humidity using the data in the Fig. 4-7 and Fig. The procedures shown in Figure 9 are illustrated. Time axis 1400 includes curve 1405, which indicates, as a function of time, whether the conditions for determining humidity are met. Time axis 1400 also includes curve 1410, which indicates, as a function of time, whether a vehicle engine is switched on or off. Time axis 1400 also includes curve 1415, which indicates, as a function of time, whether an object detection process has been initiated. Time axis 1400 also includes curve 1420, which indicates, as a function of time, whether humidity has been determined. Time axis 1400 also includes curve 1425, which indicates the amount of exhaust gas recirculation (EGR) supplied to the engine intake as a function of time. Time axis 1400 also includes curve 1430, which indicates the relative humidity as a function of time.

[0186] At time t0, the vehicle is in operation and being driven by an engine, as illustrated by curve 1410. Furthermore, it is not stated that the conditions for determining humidity are met at time t0. As discussed above, conditions for a humidity determination process that are met may include a change in ambient temperature exceeding a temperature threshold and / or a change in ambient pressure exceeding a pressure threshold since a previous (e.g., the last or immediately preceding) humidity determination.Other conditions for a humidity determination process that are met may include a threshold time of engine operation or a distance of vehicle movement that exceeds a threshold distance since a last humidity measurement, or a change in weather conditions that are indicated by other means, such as GPS and linked to the Internet, etc.

[0187] Since the vehicle is in operation and it has not been indicated that the conditions for determining humidity are met at time t0, this illustrative example does not specify that object detection is initiated, for example, via camera(s) and / or ultrasonic sensor(s). However, there may be circumstances in which the conditions for determining humidity are not met, yet object detection can still be initiated. Such examples might include a vehicle performing a parking maneuver, where camera(s) and / or in-vehicle ultrasonic sensor(s), for instance, could be used to assist with the parking operation.

[0188] Furthermore, it is not specified whether the humidity has been determined since a previous humidity measurement, as indicated by curve 1420. Therefore, it is understood that "no" with respect to curve 1420 can refer to a situation where the humidity has not been determined since a previous humidity measurement, and a current humidity measurement that is being determined can be indicated by "yes" with respect to curve 1420.

[0189] Ultimately, a specific amount of exhaust gas is recirculated to the vehicle engine intake at time t0, with the level of EGR being at least partially determined by a recent or previous humidity measurement. With respect to curve 1425, "+" can refer to an increasing level of EGR, while "-" can refer to a decreasing level of EGR. Furthermore, N / A can denote a condition where no EGR is recirculated to the engine intake, such as when the engine is not running.

[0190] At time t1, it is reported that the humidity conditions are met. Accordingly, it can be determined whether conditions for determining the humidity using an exhaust gas lambda probe (e.g., UEGO) or another oxygen sensor are met. Such an estimate can be obtained by alternating between applying a first and second voltage to the exhaust gas sensor and generating a humidity reading based on the sensor outputs at the first and second voltages, as described in [reference to...]. Fig. Section 8 describes this. However, since it is stated that the engine is running at time t1, it is not specified that the conditions for determining humidity via the exhaust gas lambda sensor are met. Instead, humidity can be determined using an ultrasonic sensor, provided that a suitable object can be identified so that an accurate measurement of humidity can be obtained.

[0191] Accordingly, object detection can be initiated at time t2. For example, object detection can involve the use of one or more vehicle cameras (e.g., 186) to identify suitable objects for subsequent humidity determination. In other examples, the ultrasonic sensors themselves can be used as an alternative to identify potentially suitable objects for humidity measurement when the vehicle is not equipped with one or more cameras.

[0192] As discussed above, object detection can, for example, involve one or more cameras capturing images and storing them on the controller (e.g., 12). Such images can be processed using object recognition algorithms stored on the controller to identify suitable objects for measuring humidity. Suitable objects might include, for example, objects stationary relative to the vehicle, objects above a predetermined threshold size, objects with a predetermined shape, objects with a specified lack of surface roughness, objects with a preferred orientation angle, and so on.

[0193] It is understood that between time t2 and time t3, a suitable object for performing a humidity measurement is identified using one or more cameras. In response to the identification of a suitable object, its position relative to the vehicle can be determined so that an optimally positioned ultrasonic sensor can be used to perform the humidity measurement. As discussed above, for example, one or more camera sensors (e.g., 187) can be used to indicate an approximate position of the object relative to the vehicle, and the controller can process this information to select an optimally positioned ultrasonic sensor for use in the humidity measurement.In particular, the selected ultrasonic sensor can be chosen based on one of the cameras detecting that the object is within the transmission path of the selected sensor. Thus, it is understood that a suitable object was detected between times t2 and t3, and an optimally positioned ultrasonic sensor was selected to perform a measurement to determine the humidity. Since the engine is running and a suitable object for performing the relative humidity measurement has been identified, it is understood that the suitable object is likely another vehicle traveling at essentially the same speed and direction as the vehicle performing the humidity measurement. Therefore, it is understood that performing a humidity measurement via ultrasonic sensors is possible while the vehicle is running (e.g.,powered by a motor or an in-vehicle energy storage device).

[0194] Between time points t2 and t3, after a suitable object has been identified and an optimal ultrasonic sensor selected, a humidity measurement can be performed. For the sake of brevity, the procedure for performing the humidity measurement is not repeated in detail here. However, it is understood that the humidity measurement can be carried out according to the above with reference to the Fig. The procedures shown in Figures 4-6 can be carried out. In short, determining humidity can involve transmitting a multitude of signals from a single sensor, each with a different frequency, receiving reflected signals of the transmitted signals, determining attenuation values ​​for each of the reflected signals that have the same transit time from transmission to reception, determining differences between pairs of attenuation values, and converting the differences into a value of relative humidity.

[0195] Accordingly, at time t3, it is indicated that the humidity has been determined. In particular, the humidity can be precisely determined as the value of the humidity indicated at time t3 in curve 1430. Once the humidity has been determined, certain vehicle parameters can be adjusted accordingly, as described above with reference to... Fig. 9 is discussed in detail. In this exemplary illustrative timeline 1400, only one vehicle operating parameter (EGR) is illustrated for clarity. As illustrated, the EGR can be reduced because the humidity has increased, in order to avoid lean engine operation due to the increased humidity. Accordingly, the EGR is reduced between times t3 and t4 according to the latest humidity measurement. Furthermore, although not explicitly shown, it is understood that the last humidity measurement can be stored on the control unit. In addition, although not explicitly shown, one or more additional vehicle operating parameters can be set in response to the humidity measurement. As discussed above, for example, a degree of advance or retardation, a limit ignition value, an estimate of the fuel octane number, etc., can be set.

[0196] At time t4, the vehicle engine is switched off. In this example timeline, it is understood that the engine shutdown includes a fuel cut-off switch-off (DFSO). However, while the engine is off, it is understood that an intake and exhaust valve on at least one cylinder may remain open, allowing the engine to circulate air through the intake manifold to the exhaust manifold.

[0197] At time t5, the conditions for determining the humidity are again met, as indicated by curve 1405. Since the engine is off due to a DFSO event, an exhaust gas lambda sensor (e.g., UEGO) can be used to determine the humidity. In other words, such an event may provide an opportunity to perform a humidity measurement via the exhaust gas lambda sensor, preferably by means of an ultrasonic sensor. A method for determining the humidity using an exhaust gas lambda sensor is described above with reference to the one in Fig. The methods described in section 9 are explained. Therefore, a detailed description of how humidity detection via an exhaust gas lambda sensor can be achieved is not repeated here. However, it is understood that humidity can be determined (reported) between times t5 and t6 using the exhaust gas lambda sensors. Accordingly, at time t6, it is indicated that a new measurement of the ambient humidity has been taken, as shown by curve 1420. Thus, the vehicle control unit can update a previous humidity reading with the last selected humidity reading.

[0198] The ambient humidity reading can be stored on the control unit, allowing the vehicle operating parameters to be adjusted accordingly. If the engine remains off from time t6 to t7, no adjustments are made to the amount of EGR supplied to the engine (e.g., none in this case, since the engine is off). However, when the engine is switched on again at time t7, the amount of EGR supplied to the engine is adjusted based on the last humidity measurement. In other words, the amount of EGR stored on the control unit is adjusted based on the humidity reading taken at time t6.

[0199] Between time t7 and t8, the vehicle is operated via the engine, with the vehicle parameters being set according to the last humidity measurement taken via the exhaust lambda sensor while the engine was switched off (e.g., rotating without fuel supply with at least one cylinder retaining the function of the intake and exhaust valves).

[0200] With reference to Fig. Figure 15 presents an exemplary time axis 1500, illustrating how a distance threshold between an object of interest and a vehicle exhaust can be set in response to a specified ambient humidity. Time axis 1500 includes curve 1505, which indicates, as a function of time, whether conditions for diesel particulate filter (DPF) regeneration are met. Time axis 1500 also includes curve 1510, which indicates a vehicle speed as a function of time. Line 1511 represents a threshold speed above which DPF regeneration can be performed without considering the position of any object relative to the vehicle's exhaust. Below the threshold speed, however, an object within a threshold distance of the exhaust can cause the DPF regeneration process to be aborted or postponed.

[0201] Accordingly, time axis 1500 also includes curve 1515, which indicates, as a function of time, whether an object is detected to be positioned near the vehicle exhaust. Time axis 1500 also includes curve 1520, which indicates, as a function of time, whether a humidity measurement has been obtained, where "no" means that no humidity measurement has been taken since a previous humidity estimate, and "yes" indicates that a current humidity measurement has been taken. Time axis 1500 also includes curve 1525, which indicates the position of an object relative to the vehicle exhaust as a function of time. In this illustrative example, "-" can refer to a decreasing distance between an object and the vehicle exhaust, whereas "+" can refer to an increasing distance between the object and the vehicle exhaust.Line 1526 refers to a first distance threshold, and line 1527 refers to a set second threshold. These thresholds can be set, for example, based on an ambient humidity reading, as discussed above and further explained below. Time axis 1500 also includes curve 1530, which indicates whether DPF regeneration is taking place ("yes") or "no".

[0202] Furthermore, the time axis 1500 also includes curve 1535, which indicates the humidity, and curve 1540, which indicates the ambient temperature as a function of time. In curve 1540, a "+" indicates an increasing (e.g., higher) temperature, while a "-" indicates a decreasing (e.g., lower) temperature.

[0203] At time t0, it is understood that the vehicle is in operation and traveling at a low speed, as indicated by curve 1510. In some examples, such a low speed may indicate a vehicle that has stopped or is essentially stationary. It is stated that the conditions for DPF regeneration are not met, as illustrated by curve 1505. Accordingly, a potential object of interest has not yet been detected, as illustrated by curve 1515, and therefore the object's position is not specified. Since the conditions for DPF regeneration are not met, no DPF regeneration process is in progress, as illustrated by curve 1530.The actual humidity is nearly 100%, as indicated by curve 1535, and furthermore, no humidity determination process has been carried out since the last time a humidity determination process was performed, as illustrated by curve 1520.

[0204] At time t1, it is indicated that the conditions for DPF regeneration are not met, as illustrated by curve 1505. As discussed above, conditions for DPF regeneration can be met in response to a threshold pressure differential being reached at the DPF, as indicated by a pressure sensor (e.g., 80) positioned upstream of the DPF and another pressure sensor (e.g., 82) positioned downstream of the DPF. Other examples might include a threshold number of miles driven since a previous DPF regeneration or a threshold duration of engine operation reached since a previous DPF regeneration.

[0205] In response to a DPF regeneration request, it can be determined whether the vehicle is traveling above a threshold speed. The threshold speed in this example timeline is illustrated by line 1511. If it is indicated that the vehicle is traveling above the threshold speed, a DPF regeneration event can be initiated without first determining whether an object or objects are near the vehicle's exhaust, since airflow due to the vehicle's speed can help cool and disperse exhaust gases, so objects near the exhaust are not a concern. However, in this example timeline, it is indicated that the vehicle is traveling essentially below the threshold speed. Accordingly, the controller can initiate a search for objects of interest located near the vehicle's exhaust.As discussed above, such a search may involve the control of one or more in-vehicle cameras (e.g., 186) commanding them to capture images near the vehicle's exhaust and processing the images using appropriate object detection algorithms to indicate whether potential objects of interest are positioned near the exhaust. In other examples, such a search may involve using one or more ultrasonic sensors (e.g., 185) to detect objects near the exhaust when a vehicle is not equipped with one or more cameras.

[0206] In this exemplary timeline, it is understood that at time t1, when the conditions for DPF regeneration are met and it is indicated that the vehicle is below the threshold speed, the control unit can command one or more in-vehicle cameras to search for objects positioned near the exhaust. Accordingly, at time t2, potential objects are detected, as indicated by curve 1515. It is also understood that during the search using one or more in-vehicle cameras, it is determined that the potential object could be suitable for determining the ambient humidity. Thus, a process for determining humidity can be carried out, as described above with reference to the Fig. 4-6 is described in detail. As discussed above, determining the ambient humidity can also be based on determining the ambient temperature. In particular, in an example where a DPF regeneration process can be performed, it may be desirable to measure the ambient temperature as close as possible (e.g., near) the vehicle exhaust, since the temperature near the exhaust can be substantially higher than the temperature further away from the vehicle due to engine operation. Furthermore, such an elevated temperature can influence the localized humidity in an environment near the exhaust, thus enabling the setting of a distance threshold to facilitate a DPF regeneration process.In particular, an area of ​​interest during a DPF regeneration process may include a region between a vehicle exhaust and an object of interest, where this region may have elevated temperatures that thus influence localized humidity within this region. Differences in localized humidity can therefore affect the thermal conductivity of the air in this defined region, as described above with reference to the following. Fig. 10-11 discussed, and thus determining the temperature and humidity specific to this area can enable the setting of a distance threshold to allow a DPF regeneration process.

[0207] At time t3, it is indicated that a process to determine humidity was completed and that ambient humidity was determined. As above and with reference to the Fig. As discussed in sections 10-11, the thermal conductivity of air can vary depending on the percentage of humidity. Therefore, knowledge of the ambient temperature can allow for the setting of a distance threshold to trigger or prevent a DPF regeneration process. Accordingly, a distance threshold can be set at time t3. In particular, a distance threshold can be set at a first threshold level, as indicated by line 1526. In such an example, a DPF regeneration event can be prevented from occurring and postponed if an object is positioned closer to the exhaust than the threshold. However, if an object is positioned at a greater distance from the exhaust than the threshold, a DPF regeneration process could be initiated.In this exemplary time axis, the distance threshold can be set based on the specified humidity and temperature, where the temperature can correspond to a temperature substantially close to the vicinity of the exhaust and where the humidity can correspond to a localized humidity level in the vicinity of the exhaust (e.g., roughly between the exhaust and an object of interest). In particular, the distance threshold can be set from the first threshold level, indicated by line 1526, to a second threshold level, indicated by curve 1527.

[0208] With the threshold set at time t3, the distance of the object of interest from the vehicle exhaust can be determined between times t3 and t4 using the ultrasonic sensor (e.g., 185). To improve the operational use of the ultrasonic sensor, a distance detection threshold can be set based on the specified humidity and temperature, as described above with reference to step 1155. Fig. 11 and with reference to step 1230 at Fig. This is discussed in detail in section 12. Thus, a distance measurement between times t3 and t4 can be performed using the ultrasonic sensor, allowing the object's position at time t4 to be determined. Since the distance threshold has been set to the second threshold value, as indicated by line 1527, and since the object is positioned at a greater distance exceeding the set threshold value, a DPF regeneration process can be initiated. Accordingly, DPF regeneration is started at time t4, as indicated by curve 1530.

[0209] As discussed above, DPF regeneration can involve adjusting engine operating parameters to increase the DPF temperature. Examples include operating a heating device (e.g., 75) coupled to the DPF or increasing the engine exhaust temperature through rich running or direct fuel injection into the exhaust.

[0210] DPF regeneration can be performed between time points t4 and t5. Although not explicitly shown, it is understood that one or more of the vehicle's internal camera(s) and ultrasonic sensor(s) can continue to be used during the DPF regeneration process to indicate whether an object has moved into an area below the set threshold distance. In such a case, where it is indicated that an object has fallen below the set threshold distance, the regeneration event can be terminated and, in some examples, postponed.

[0211] Furthermore, soot buildup between times t4 and t5, while the DPF regeneration process is in progress, can be monitored, for example, via a pressure differential across the DPF. The DPF regeneration process can then be terminated when the pressure differential drops to a predetermined threshold.

[0212] Accordingly, it is understood that the DPF was regenerated at time t5. Consequently, the DPF regeneration process is terminated, as indicated by curve 1530, since the conditions for DPF regeneration are no longer met, as indicated by curve 1505. Furthermore, object detection processes can be terminated, as it is no longer necessary to indicate whether an object is positioned in close proximity to the vehicle exhaust, as indicated by curve 1515.

[0213] Between time t5 and t6, the vehicle speed increases as the vehicle resumes typical driving operation.

[0214] Humidity can be measured using an in-vehicle ultrasonic sensor. This measurement can then be used to set a distance detection threshold for the ultrasonic sensor, thus improving its operational performance.

[0215] The technical benefit lies in recognizing that relative humidity can be determined using a single ultrasonic sensor, provided an ambient temperature is specified and, furthermore, provided that a multitude of signals transmitted and received by the ultrasonic sensor are processed for attenuation values ​​only if the signals have the same propagation delay. By restricting the determination of attenuation values ​​to those signals with the same propagation delay, factors that can contribute to noise in humidity determination, such as surface angular roughness and target angle, can be compensated for. Such attenuation values ​​can therefore be subtracted from one another if the attenuation differences can be converted into relative humidity values.

[0216] The ones mentioned here and with reference to the Fig. 1-2 and Fig. 8 systems described together with those presented here and with reference to the Fig. 4-7, Fig. 9 and Fig.The methods described in sections 11-12 can enable one or more systems and one or more procedures. In one example, a procedure includes transmitting a plurality of signals from a single sensor, each at a different frequency; receiving reflected signals of the transmitted signals; changing the frequency of the transmitted signals to achieve a desired signal-to-noise ratio; determining attenuation values ​​for each of the reflected signals that have the same propagation time from transmission to reception; determining differences between pairs of attenuation values; and converting the differences into a statement of relative humidity. In a first example of the procedure, the method further includes: changing the frequencies of the transmitted signals in response to a determination that the reflected signals have, or would have, an undesired signal-to-noise ratio.A second example of the method optionally includes the first example and further includes: wherein the frequency of the transmitted signals is changed in response to environmental conditions, including one or more of the following: ambient temperature; ambient humidity; and the propagation time from transmission to reception of the transmitted and reflected signals. A third example of the method optionally includes one or more or all of the first and second examples and further includes setting a distance detection threshold with the specified relative humidity, wherein setting the distance detection threshold includes: specifying suitable frequencies for performing a distance measurement; and selecting an optimal frequency for performing the distance measurements in response to the set distance detection threshold.A fourth example of the method optionally includes one, more, or all of the examples from the first three and further includes equipping a motor vehicle with the sensor and detecting the absence of a parked vehicle to assist in parallel parking by selecting a frequency or frequencies corresponding to the set distance detection threshold. A fifth example of the method optionally includes one, more, or all of the examples from the first three and further includes: wherein the transmitted signals comprise a chirp signal. A sixth example of the method optionally includes one, more, or all of the examples from the first three and further includes: wherein the individual sensor comprises an ultrasonic sensor and the transmitted signals comprise sound waves.A seventh example of the procedure may include one or more or all of the examples from the first to sixth and further includes: wherein the conversion of the attenuation difference involves the use of a transfer function to convert the attenuation difference into a measurement of the relative humidity.

[0217] Another example of a procedure involves transmitting a multitude of signals from a single sensor mounted on a vehicle, each transmission occurring at a different frequency; receiving reflected signals of the transmitted signals; determining attenuation values ​​only for each of the reflected signals that have the same propagation time from transmission to reception; determining differences between pairs of attenuation values; converting the differences into a relative humidity reading; setting a distance detection threshold for the sensor in response to the relative humidity reading; and using the sensor to perform a distance measurement based on a desired operational use of the sensor.In a first example of the method, the method further includes: wherein the transmitted signals comprise sound waves and wherein the individual sensor comprises an ultrasonic sensor. A second example of the method optionally includes the first example and further includes changing the frequencies of the transmitted signals in response to a determination that the reflected signals have, or would have, a signal-to-noise ratio below a predetermined threshold; and wherein the changing of the frequencies of the transmitted signals takes place prior to determining differences between pairs of attenuation values ​​and converting the differences into a statement of relative humidity.A third example of the method may include one, more, or all of the elements from the first and second examples and further includes measuring an ambient air temperature, wherein the conversion of the differences between pairs of attenuation values ​​into the expression of the relative humidity is based on the measured ambient air temperature. A fourth example of the method may include one, more, or all of the elements from the first to third examples and further includes: wherein, by determining attenuation values ​​only for each of the reflected signals that have the same propagation time from transmission to reception, deviations in the target surface angle and the reflecting surface roughness are corrected.A fifth example of the method may optionally include one or more or all of the examples from the first to fourth and further includes powering the vehicle at least in part by an engine comprising an intake manifold and an exhaust manifold, wherein the engine is powered by the combustion of fuel supplied by the engine; controlling an amount of exhaust gas recirculated to the intake manifold of the engine while the engine is operating; and adjusting vehicle operating parameters in response to the specified relative humidity, wherein the adjusting of vehicle operating parameters includes one of at least one measure of exhaust gas recirculation supplied to the engine and one measure by which the ignition supplied to the fuel for combustion is retarded or advanced.A sixth example of the procedure may include one or more or all of the examples from the first to fifth and further includes: where setting the distance detection threshold for the sensor in response to the specified relative humidity includes specifying suitable frequencies for carrying out distance measurements depending on the specified relative humidity.A seventh example of the method may include one or more or all of the examples from the first to sixth and further includes: wherein the use of the sensor to perform a distance measurement based on a desired operational use of the sensor includes determining whether an object of interest is positioned at a short range, medium range or long range away from the sensor; and further includes selecting an optimal frequency, wherein the optimal frequency depends on the set distance detection threshold and the desired operational use of the sensor.An eighth example of the method may include one or more or all of the examples from the first to seventh and further includes capturing a large number of images of an environment near the vehicle via one or more in-vehicle cameras, wherein the desired operational use of the sensor is determined at least in part by the one or more cameras.

[0218] An example of a system for a vehicle includes one or more ultrasonic sensors positioned at various points on the vehicle; an ambient air temperature sensor; and a controller that stores instructions in non-volatile memory which, when executed, cause the controller to: measure the ambient air temperature; command the ultrasonic sensor to transmit and receive a plurality of ultrasonic signals from a single ultrasonic sensor; specify signals that have the same propagation time from transmission to reception; determine attenuation values ​​for those signals that have the same propagation time from transmission to reception; determine differences between pairs of attenuation values; convert the differences into a relative humidity reading using a transfer function; and set a distance detection threshold for the one or more sensors.where setting the distance detection threshold involves specifying suitable frequencies for performing distance measurements depending on the specified relative humidity. In a first example, the system further includes: where the controller further stores instructions in non-volatile memory which, when executed, cause the controller to: before determining differences between pairs of attenuation values, change frequencies of the transmitted signals in response to a specification that a signal-to-noise ratio of the received signals is below a predetermined threshold. A second example of the system optionally includes the first example and further includes: where the controller further stores instructions in non-volatile memory which, when executed, cause the controller to: determine an optimal frequency,which is to be used to determine the distance between an object and the one or more sensors in response to the set distance detection threshold, wherein the sensor used to determine the distance is either the same sensor used to determine the relative humidity or a different sensor; and wherein determining the optimal frequency involves specifying whether the object is positioned at a short range, medium range, or long range from the sensor.

[0219] It should be noted that the exemplary control and estimation routines contained herein can be used with various engine and / or vehicle system configurations. The control procedures and routines disclosed herein can be stored as executable instructions in non-volatile memory and executed by the control system, including the controller, in combination with the various sensors, actuators, and other engine hardware. The specific routines described herein can represent one or more from any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. Accordingly, various illustrated actions, operations, and / or functions can be performed in the illustrated sequence or in parallel, or in some cases, omitted.Similarly, the processing sequence is not strictly necessary to achieve the features and advantages of the exemplary embodiments described here, but is provided for the sake of simplicity. One or more of the illustrated actions, processes, and / or functions can be performed repeatedly, depending on the specific strategy employed. Furthermore, the described actions, processes, and / or functions can graphically represent code that is to be programmed onto non-volatile memory of the computer-readable storage medium in the engine control system, whereby the described actions are executed by carrying out the instructions in a system that includes the various engine hardware components in combination with the electronic control unit.

[0220] It is understood that the configurations and routines disclosed herein are exemplary and that these specific embodiments are not to be interpreted in a limiting sense, as numerous variations are possible. For example, the foregoing technology can be applied to V-6, I-4, I-6, V-12, 4-cylinder boxer, and other engine types. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations and other features, functions, and / or properties disclosed herein.

[0221] The following claims, in particular, describe certain combinations and subcombinations that are considered novel and not obvious. These claims may refer to "one" element, "a first" element, or the equivalent thereof. Such claims are to be understood as including one or more such elements and neither requiring nor excluding two or more such elements. Further combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amending the present claims or by filing new claims in this or a related application. Such claims, regardless of whether they have a broader, narrower, the same, or different scope compared to the original claims, are also considered to be included in the subject matter of the present disclosure.

Claims

[1] Procedure, encompassing: Transmitting a multitude of signals from a single sensor, each at a different frequency; Receiving reflected signals of the transmitted signals; Changing the frequency of the transmitted signals to achieve a desired signal-to-noise ratio; Determining attenuation values ​​only for each of the reflected signals that have the same propagation time from transmission to reception; Determining differences between pairs of damping values; and Converting the differences into a measurement of relative humidity. [2] Method according to claim 1, wherein the frequency of the transmitted signals is changed in response to a determination that the reflected signals have or would have an undesirable signal-to-noise ratio. [3] The method of claim 1, wherein the frequency of the transmitted signals is changed in response to environmental conditions, including one or more of the following: Ambient temperature; ambient humidity; and the transit time from transmission to reception of the transmitted and reflected signals. [4] Method according to claim 1, wherein the changing of the frequency of the transmitted signals takes place before determining differences between pairs of attenuation values ​​and converting the differences into a specification of the relative humidity. [5] The method of claim 1, further comprising: Setting a distance detection threshold with the specified relative humidity, wherein setting the distance detection threshold includes specifying suitable frequencies for performing a distance measurement; and Selecting an optimal frequency for performing distance measurements in response to the set distance detection threshold. [6] Method according to claim 5, further comprising equipping a motor vehicle with the sensor and detecting the absence of a parked vehicle to assist in parallel parking of the motor vehicle by selecting a frequency or frequencies corresponding to the set distance detection threshold. [7] Method according to claim 6, further comprising: Propelling the motor vehicle at least partially by an engine comprising an intake manifold and an exhaust manifold, and wherein the engine is powered by combustion of fuel supplied by the engine; Controlling the amount of exhaust gas that is recirculated to the engine's intake manifold while the engine is running; and Adjusting vehicle operating parameters in response to the specified relative humidity, wherein the adjustment of vehicle operating parameters includes adjusting at least one measure of exhaust gas recirculation provided to the engine and / or a measure by which the ignition provided to the engine for combustion is delayed or advanced. [8] Method according to claim 1, wherein transmitted signals include a chirp signal. [9] Method according to claim 1, wherein the individual sensor comprises an ultrasonic sensor and the transmitted signals comprise sound waves. [10] Method according to claim 1, wherein the conversion of the attenuation difference comprises the use of a transfer function to convert the attenuation difference into a measurement of the relative humidity. [11] Method according to claim 1, wherein by determining attenuation values ​​only for each of the reflected signals which have the same transit time from transmission to reception, deviations in the target surface angle and the reflecting surface roughness are corrected. [12] System for a vehicle, comprising: one or more ultrasonic sensors positioned at different points on the vehicle; an outdoor air temperature sensor; and A controller that stores instructions in non-volatile memory which, when executed, cause the controller to: Measuring the ambient air temperature; Commands to the ultrasonic sensor to transmit and receive a multitude of ultrasonic signals from a single ultrasonic sensor; Specifying signals that have the same transit time from transmission to reception; Determining attenuation values ​​for those signals that have the same propagation time from transmission to reception; Determining differences between pairs of damping values; Converting the differences into a measurement of relative humidity using a transfer function; Setting a distance detection threshold for one or more sensors, wherein setting the distance detection threshold includes specifying suitable frequencies for performing distance measurements depending on the relative humidity. [13] System according to claim 12, wherein the controller further stores instructions in the non-volatile memory which, when executed, cause the controller to: Before determining differences between pairs of attenuation values, changes are made to the frequencies of the transmitted signals in response to a statement that the signal-to-noise ratio of the received signals is below a predetermined threshold. [14] System according to claim 12, wherein the controller further stores instructions in the non-volatile memory which, when executed, cause the controller to: Determining an optimal frequency to be used for determining the distance between an object and the one or more sensors in response to the set distance detection threshold, wherein the sensor used to determine the distance is either the same sensor used to determine the relative humidity or a different sensor; and Determining the optimal frequency involves specifying whether the object is positioned at a short, medium, or long range from the sensor. [15] System according to claim 14, wherein the controller further stores instructions in the non-volatile memory which, when executed, cause the controller to: Detecting the absence of a parked vehicle to assist in parallel parking by determining the optimal frequency in response to the set distance detection threshold.

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