A system for use in a vehicle

Abstract

System for determining whether a vehicle's ride height should be prevented from being lowered when the vehicle speed exceeds a speed threshold, the system comprising the following: a processor with one input configured to receive driving attribute data from at least one onboard vehicle driving attribute sensor, wherein the driving attribute data specifies the unevenness of the surface over which the vehicle is traveling; and a data storage device configured to store at least one predetermined driving attribute threshold for the driving attribute sensor or sensors, wherein the processor is configured to calculate a driving attribute parameter depending on the driving attribute data received for the driving attribute sensor or sensors; and wherein the processor is configured to compare the or each calculated driving attribute parameter with the corresponding at least one predetermined driving attribute threshold to determine whether the vehicle is driving on a smooth surface or an uneven surface, and to lower the ride height if the vehicle speed exceeds the speed threshold, unless it is determined that the vehicle is driving on an uneven surface.

Description

TECHNICAL AREA

[0001] The present disclosure relates to a system for use in a vehicle and, in particular, but not exclusively, to a system for determining whether the ride height of a vehicle should be adjusted. Aspects of the invention relate to a system, a vehicle, and a method. STATE OF THE ART

[0002] Lowering a vehicle's ride height or suspension offers many advantages. For example, it's known that a vehicle's aerodynamic handling can be improved when the body sits lower to the road surface. This is because the reduced airflow between the vehicle's chassis and the surface leads to reduced drag. This, in turn, can improve the vehicle's fuel efficiency.

[0003] From DE 38 26 843 A1 a suspension system for motor vehicles is known with a speed-dependent level control for lowering the vehicle relative to the road level at increased speed, including height-adjustable support or spring units.

[0004] Lowering the ride height can also improve traction and / or vehicle handling. The lowered center of gravity can reduce longitudinal and lateral weight transfer during dynamic maneuvers. This can lead to reduced variation in tire contact force, which in turn can improve grip between the tires and the road surface.

[0005] Another advantage of lowering the ride height is increased driver comfort due to reduced body roll. The vehicle's stability in crosswinds can also be improved, which is particularly desirable when, for example, overtaking commercial vehicles on a highway.

[0006] Some or all of the above advantages can be particularly noticeable when the vehicle is traveling at relatively high speeds, such as on a highway. Current systems are designed to automatically lower a vehicle's ride height when the vehicle speed exceeds a preset value. However, lowering the ride height in such cases is not always desirable, as this can negatively impact ride quality, for example, by reducing passenger comfort.

[0007] One objective of the present invention is to address one or more of the problems associated with the prior art. BRIEF SUMMARY OF THE INVENTION

[0008] According to one aspect of the present invention, a system is provided for determining whether a vehicle's ride height should be prevented from lowering when the vehicle speed exceeds a speed threshold. The system includes a processor with an input configured to receive vehicle driving attribute data from at least one onboard vehicle driving attribute sensor, wherein the vehicle driving attribute data indicates the unevenness of the surface over which the vehicle is traveling, and a data memory configured to store at least one predetermined vehicle driving attribute threshold for the driving attribute sensor or sensors. The processor is configured to calculate a driving attribute parameter as a function of the received driving attribute data for the driving attribute sensor or sensors.The processor is also configured to compare the calculated vehicle driving attribute parameter(s) with the corresponding at least one predetermined vehicle driving attribute parameter to determine whether the vehicle is driving on a smooth or uneven surface, and to lower the ride height if the vehicle speed exceeds the speed threshold, unless it is determined that the vehicle is driving on an uneven surface.

[0009] The speed threshold can correspond to a speed at which a standard vehicle speed reduction system is typically operational, which may be a relatively high speed. For example, the speed threshold may be approximately 50 mph (80.47 km / h) or, more specifically, higher than approximately 65 mph (104.61 km / h). The speed threshold can be any suitable speed.

[0010] In a standard vehicle speed reduction system, the vehicle ride height is automatically lowered when the vehicle speed exceeds the speed threshold (i.e., increases to a relatively high speed). However, lowering the vehicle ride height can reduce vehicle comfort (or handling) and can increase the likelihood of damage to the vehicle suspension. This is particularly true when the vehicle travels over surfaces of relatively low quality, i.e., relatively uneven surfaces. The present invention is advantageous in that the vehicle ride height is not automatically lowered when the vehicle speed exceeds the speed threshold, but rather an additional determination regarding the quality of the surface over which the vehicle travels is made before this occurs.In particular, if it is determined that the surface quality is such that lowering the ride height would adversely affect vehicle performance (i.e., an "uneven" surface), the system will prevent the ride height from being lowered. This significantly reduces the deterioration in ride comfort when driving on such uneven, gravel, or non-gravel surfaces.

[0011] The system can operate at any speed. In this case, the system is configured to first determine whether the current vehicle speed exceeds a predetermined speed threshold. The system can then be configured to compare the received and predetermined driving attribute data to display a surface roughness warning only when the system determines that the vehicle is traveling above the speed threshold.

[0012] In embodiments, the processor comprises an electronic processor with an electrical input for receiving the driving attribute data, and the data storage comprises an electronic storage device that is electrically coupled to the electronic processor and contains instructions stored therein. In these embodiments, the processor is configured to access the storage device and execute the instructions stored therein, enabling it to calculate the driving attribute parameter(s) based on the received driving attribute data.The processor is also configured to compare the calculated driving attribute parameter(s) with the corresponding at least one predetermined driving attribute threshold to determine whether the vehicle is driving on a smooth or uneven surface, and to prevent a reduction in ride height if it is determined that the vehicle is driving on an uneven surface.

[0013] The processor can have an output configured to send a control signal to one or more vehicle suspension components, depending on whether a reduction in vehicle ride height should be prevented. The vehicle suspension components include one or more suspension springs, shock absorbers, tires, and linkages.

[0014] In some embodiments, the input is configured to receive a current vehicle speed from a vehicle speed sensor, and the processor is configured to determine whether the current vehicle speed is greater than the speed threshold.

[0015] The processor can include at least one bandpass filter configured to attenuate received driving attribute data in order to calculate the driving attribute parameter(s). This allows signals of interest to be retained and analyzed while simultaneously reducing distant interference.

[0016] The processor can include at least one absolute value calculator configured to calculate the absolute value of the received driving attribute data in order to calculate each driving attribute parameter. This simplifies the subsequent signal analysis process, as, for example, the number of thresholds to be considered can be reduced by half; that is, only thresholds for positive values ​​need to be considered.

[0017] The processor can have at least one exponentially weighted moving average filter configured to calculate a moving average of the received driving attribute data at predefined intervals and to assign exponential weights to the calculated moving averages to calculate each driving attribute parameter. The use of exponentially weighted moving averages means that the vehicle does not react to every "uneven road" event and protects against repeated ride height adjustments over a relatively short period.

[0018] The at least one predetermined driving attribute threshold can include an ON / OFF threshold for the sensor(s), where a value of the calculated driving attribute parameter(s) above the corresponding ON / OFF threshold indicates an uneven surface, and a value of the calculated driving attribute parameter(s) below the corresponding ON / OFF threshold indicates a smooth surface. The processor can determine that lowering the vehicle ride height should be prevented if at least one of the calculated driving attribute parameters is above or, alternatively, below the corresponding ON / OFF threshold.

[0019] The at least one predetermined driving attribute threshold can include an ON threshold for the sensor(s), where a temporal increase in the calculated driving attribute parameter from below the corresponding ON threshold above the corresponding ON threshold indicates an uneven surface. The system can be calibrated such that a temporal decrease in the calculated driving attribute parameter from above the corresponding ON threshold to below the corresponding ON threshold indicates an uneven surface.

[0020] The processor can determine that lowering the vehicle's ride height should be prevented if at least one of the calculated driving attribute parameters increases or decreases over time above the corresponding ON threshold.

[0021] The at least one predetermined driving attribute threshold can include an OFF threshold for the sensor(s), where each OFF threshold is lower than the corresponding ON threshold, and where a temporal decrease, or alternatively a decrease in the calculated driving attribute parameter from above or alternatively from below the corresponding OFF threshold to below or alternatively above the corresponding OFF threshold, indicates a smooth surface. The use of ON and OFF thresholds prevents flickering between "uneven" and "smooth" events and thus prevents the ride height from being adjusted multiple times over a relatively short period.

[0022] The processor can determine that lowering the vehicle's ride height should only not be prevented if each of the calculated driving attribute parameters decreases below the corresponding OFF threshold value over time, or alternatively, increases.

[0023] The driving attribute data may include a measurement of vehicle roll rate, vehicle pitch rate, and / or vehicle lift acceleration. The driving attribute data may include a measurement of vehicle wheel speed and / or vehicle body height relative to a wheel. The driving attribute data may include radar sensor output data from at least one onboard radar sensor. The driving attribute data may include acoustic sensor output data from at least one onboard acoustic sensor. A specific combination of driving attribute data from specific sensors may be used depending on the type of surface, i.e., the type of "roughness" of interest. A rough surface may include some or all of the following: potholes, waves, speed bumps, tree roots, ditch repairs, off-road speed bumps, sunken manhole covers, corrugated roads, paving, and ribs.

[0024] The driving attribute data can be received from at least one sensor in an inertial measurement unit.

[0025] The driving attribute data can be received from at least two onboard vehicle driving attribute sensors, and the processor is configured to compare the calculated driving attribute parameters with the corresponding predetermined driving attribute thresholds to determine whether to prevent the vehicle from lowering to at least one of at least two lowered vehicle ride height positions. The system can determine degrees of surface unevenness to, for example, prevent the lowest possible ride height, but not to prevent lowering to other, less low ride heights.

[0026] If the vehicle's ride height has been lowered to a lowered position, the processor can be configured to send a control signal to raise the ride height to a raised position if the vehicle is determined to be traveling on an uneven surface. This ensures that when the vehicle transitions from a lowered ride height on a relatively smooth surface to a non-smooth surface, the system reacts to ensure the ride height is adjusted appropriately; that is, the system is not limited to lowering the ride height but can also actively command it to raise it.

[0027] According to a further aspect of the present invention, a method is provided for determining whether a lowering of the ride height of a vehicle should be prevented when the vehicle speed exceeds a speed threshold. The method comprises receiving driving attribute data from at least one on-board vehicle driving attribute sensor, wherein the driving attribute data indicates the unevenness of the surface over which the vehicle is traveling, and storing at least one predetermined driving attribute threshold for the driving attribute sensor or sensors.The method also includes calculating a driving attribute parameter based on the received driving attribute data for each driving attribute sensor and comparing the calculated driving attribute parameter(s) with the corresponding at least one predetermined vehicle driving attribute threshold to determine whether the vehicle is driving on a smooth or uneven surface. The method includes lowering the ride height if the vehicle speed exceeds the speed threshold, unless it is determined that the vehicle is driving on an uneven surface.

[0028] According to a further aspect of the present invention, a method for determining whether a lowering of the ride height of a vehicle should be prevented is provided, wherein the method comprises receiving a current vehicle speed from a vehicle speed sensor and vehicle driving attribute data from at least one on-board vehicle driving attribute sensor, wherein the vehicle driving attribute data indicate the unevenness of the surface over which the vehicle is driving, and determining whether the current vehicle speed is greater than a stored vehicle speed threshold.If the current speed is greater than the speed threshold, the method further comprises calculating a driving attribute parameter based on the received driving attribute data for the driving attribute sensor(s) and comparing the calculated vehicle driving attribute parameter(s) with at least one stored corresponding predetermined vehicle driving attribute threshold to determine whether the surface is uneven or smooth. If it is determined that the surface is uneven, the method then comprises sending a control signal to one or more vehicle suspension components to prevent the vehicle from lowering.

[0029] According to another aspect of the present invention, a vehicle is provided which includes a system as described above.

[0030] According to yet another aspect of the present invention, a non-volatile, computer-readable storage medium is provided on which instructions are stored which, when executed by one or more processors, cause the one or more processors to execute one or more of the methods defined above.

[0031] For the purposes of this disclosure, it is pointed out that the suspension system described herein may comprise a control unit or a computing device with one or more electronic processors. A vehicle and / or a system thereof may comprise a single control unit or electronic control device, or alternatively, different control device functions may be embodied or incorporated in different control units or devices. As used herein, the term "vehicle suspension system" is intended to include both a single control unit or device and multiple control units or devices operating together to provide the required control functionality.A set of instructions could be provided which, when executed, cause the control device(s) or control unit(s) to implement the control techniques described herein (including the procedure(s) below). The set of instructions could be embedded in one or more electronic processors, or alternatively, the set of instructions could be provided as software executed by one or more electronic processors. For example, a first control device could be implemented in software running on one or more electronic processors, and one or more other control devices could also be implemented in software running on one or more electronic processors, optionally the same or the same multiple processors as the first control device.It should be noted, however, that other arrangements are also suitable and therefore the present invention does not intend to limit any particular arrangement. In any case, the embodiments described above can be embedded in a computer-readable storage medium (e.g., a non-volatile storage medium) that incorporates any mechanism for storing information in a form readable by a machine or an electronic processor / computing device, including, but not limited to: a magnetic storage medium (e.g., a floppy disk); an optical storage medium (e.g., a CD-ROM); a magneto-optical storage medium; a read-only memory (ROM); a random access memory (RAM); a erasable storable memory (e.g., EPROM or EEPROM); a flash memory; or electrical or other types of media for storing such information / instructions.

[0032] Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples, and alternatives presented in the preceding paragraphs, in the claims, and / or in the following description and drawings, and in particular their individual features, may be considered independently of one another or in any combination. This means that all embodiments and / or features of any embodiment may be combined in any way and / or in any combination, provided that these features are not incompatible.The applicant reserves the right to amend any originally filed patent claim or to file any new patent claim accordingly, including the right to amend any originally filed patent claim to depend on and / or incorporate any feature of any other patent claim, even if it was not previously claimed in this manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] One or more embodiments of the invention will now be described exclusively by way of example with reference to the accompanying drawings, which show: Fig. 1a a schematic top view of a vehicle including a vehicle suspension system (VSS) according to an embodiment of the present invention, wherein the vehicle also includes on-board sensors and suspension components; Fig. 1b a side view of the vehicle in a raised position; and Fig. 1c a side view of the vehicle in a lowered position; Fig. 2 the components of the in Fig. 1 VSS shown together with the inputs to and outputs from the VSS; Fig. 3. A smooth terrain recognition component (STR) as part of the VSS. Fig. 2 more detailed; Fig. 4 a procedure that starts from the STR Fig. 3 is carried out to determine whether the surface over which the vehicle is driving is ‘uneven’ or ‘smooth’; Fig. 5 curves of vehicle driving attribute data as a function of time for a relatively "smooth" surface, where the vehicle driving attribute data is based on measurements by the on-board sensors of Fig. 1 and based; and specifically Fig. 5a a measure of the vehicle roll rate; Fig. 5b a measure of the vehicle's tilt rate; Fig. 5c a measure of vehicle lifting acceleration; and Fig. 5d Determining whether the surface is "uneven" or "smooth" based on the information in the Fig. 5a, b, c shown data; Fig. 6 the corresponding curves from Fig. 5 for a relatively “uneven” surface; and Fig. 7 from the VSS Fig. 2. Procedure carried out to determine whether the vehicle's ride height is due to the Fig. 1 should be adjusted. DETAILED DESCRIPTION

[0034] In one embodiment of the present invention, a vehicle suspension system determines the roughness of the surface over which the vehicle travels when the vehicle exceeds a limiting speed and then uses this determination to decide whether to prevent the vehicle from lowering. Similarly, this determination can be used to decide whether to raise the vehicle's ride height from a lowered position to a raised position.

[0035] Fig. Figure 1(a) shows a top view of a vehicle 10 comprising a vehicle body 12 and four wheels 14. The vehicle 10 also includes one or more onboard vehicle sensors 16, a vehicle suspension system (VSS) 18 according to an embodiment of the present invention, and vehicle suspension components 20. The suspension components 20 include one or more components that connect the wheels 14 to the rest of the vehicle 10 to cause the vehicle's ride height to be raised or lowered. These components 20 may include suspension springs, shock absorbers, and linkages. The suspension components 20 may also include the vehicle tires.

[0036] The Fig. 1b and Fig. Figure 1c shows side views of the vehicle 10 in "raised" and "lowered" vehicle ride height positions 22 and 24, respectively. The vehicle ride height, which can also be referred to as ground clearance, can be defined in any suitable way. In the embodiment described here, the ride height is the shortest distance between the surface 28 and a specific part of the vehicle 10 that is not designed to continuously contact the surface 28, i.e., not the tires. This can be a defined part of the vehicle chassis or the vehicle body and is consistently referred to simply as the chassis. In the raised position 22, the chassis 26 of the vehicle body 12 is arranged at a first distance D1 from the surface 28 over which the vehicle 10 travels. In the lowered position 24, the chassis 26 of the vehicle body 12 is positioned at a second distance D2 from the surface 28, where D2 is less than D1.Typically, the difference between D1 and D2 can be between approximately 5 mm and 50 mm, and more specifically approximately 15 mm, although the difference can be any other suitable value.

[0037] The VSS 18 can cause the vehicle body 12 to be raised or lowered between ride height positions 22 and 24 by sending control signals to the suspension components 20. For example, to adjust the ride height of the vehicle 10 between the raised and lowered positions 22 and 24, the VSS 18 can change the amount of air in the springs using a compressor, such as an electric pump, or a stored volume of air, such as a pressure accumulator (for a vehicle using air suspension).

[0038] Fig. Figure 2 shows the VSS 18 in more detail. The VSS 18 includes a processor 30 for determining whether the vehicle 10's ride height should be adjusted between the raised and lowered positions 22, 24. The processor 30 includes a detection module 32 for smooth terrain detection (STR). The STR 32 is used to determine whether the surface 28 over which the vehicle 10 travels is "smooth" or "uneven." The result of this determination is used by the processor 30 to determine whether a ride height adjustment is necessary.

[0039] The data processor 30 has an input 36 configured to receive data from the onboard sensors 16. In particular, the processor 30 receives vehicle driving attribute data used by the STR 32 to determine whether the surface 28 is uneven or smooth. In the embodiment described herein, the vehicle driving attribute data includes measurements of the vehicle roll rate, vehicle pitch rate, and vehicle lift acceleration (i.e., vertical acceleration). The onboard sensors 16 may include separate roll, pitch, and lift sensors, or the roll, pitch, and lift data may be received from a single inertial measurement unit (IMU) that includes a multidimensional accelerometer for measuring both linear and rotational accelerations in one or more directions.Such a multidimensional accelerometer can be considered, for the purposes of this description, as three separate sensors transmitting three different sets of driving attribute data. Typical intervals for the sensor data can be ±15 radians per second for vehicle roll, ±10 radians per second for vehicle pitch, and ±4 meters per second for vehicle lift.

[0040] Processor 30 also receives vehicle speed reduction data, which is used to determine whether the ride height is adjusted appropriately. Typically, this data includes vehicle speed data from a speed sensor on the vehicle 10. In short, lowering the ride height is generally only appropriate if the vehicle speed exceeds a high-speed threshold. This is discussed in more detail below.

[0041] The VSS 18 includes a data storage device 34 in which instructions are stored, the data processor 30 being configured to execute these instructions to determine whether the surface is uneven or smooth and to determine whether the ride height should be adjusted. The data storage device 34 may be an electronic, non-volatile, computer-readable storage medium. The data storage device 34 also includes predefined vehicle driving attribute data and predefined vehicle speed reduction data, which are used by the processor 30 to execute the foregoing determinations.

[0042] The processor 30 has an output 38 which is configured to send a control signal to the suspension components 20. In particular, the control signal controls the suspension components 20 to switch the vehicle ride height from the raised position 22 to the lowered position 24 or from the lowered position 24 to the raised position 22, as described below.

[0043] Fig. Figure 3 shows the structure of the STR 32 in more detail. Specifically, the STR 32 contains low-pass filters 40a, 40b, 40c, high-pass filters 42a, 42b, 42c, absolute value calculators 44a, 44b, 44c, exponentially weighted moving average filters 46a, 46b, 46c, and relay blocks 48a, 48b, 48c for processing each of the respective received roll rate signals 50a, tilt rate signals 50b, and lift acceleration signals 50c. The signals 50a, 50b, 50c are processed in parallel. The received driving attribute data 50a, 50b, 50c are processed by these filters to calculate so-called driving attribute parameters, which can then be analyzed.

[0044] Taking the roll rate signal 50a as an example, the low-pass filter 40a receives inputs of the raw roll rate data from the sensors 16, a predetermined upper threshold roll rate value 52a from the data memory 34, and a filter sampling rate constant 53a, i.e., a calibration constant representing the system's execution rate, also from the data memory 34. The low-pass filter 40a acts by attenuating any part of the received roll rate signal 46a with a frequency above the upper threshold 52a and by passing any part of the signal 50a below the threshold 52a, and outputs the processed signal. In the embodiment described here, the upper threshold 52a is 20 Hz; however, any other suitable value can be used.

[0045] Similarly, the high-pass filter 42a receives inputs of the processed roll rate data from the low-pass filter 40a, a predetermined lower threshold roll rate value 54a from the data memory 34, and a filter sampling rate constant 55a. The high-pass filter 42a acts to attenuate any portion of the processed roll rate signal with a frequency below the lower threshold 54a and to pass any portion of the signal above the threshold 54a, and outputs the processed signal. In the embodiment described here, the lower threshold 54a is 4 Hz; however, any other suitable value may be used.

[0046] The low-pass and high-pass filters 40a and 42a can be collectively referred to as band-pass filters 40a and 42a, and this filter acts to smooth the received roll rate signal 50a before it is analyzed, so that short-term fluctuations are removed while maintaining the overall trend of the signal. In particular, all frequencies that do not help to distinguish between "rough" and "smooth" surfaces are filtered out.

[0047] The roll rate signal 50a can contain both positive and negative values, corresponding to the roll acceleration of the vehicle 10 in both the left and right directions. To analyze the signal, its absolute value is determined and output by the absolute value calculator 44a.

[0048] The exponentially weighted moving average filter 46 ensures that the roll rate signals 50a most recently received by the processor 30 are given greater weight in the analysis for detecting smooth or uneven terrain. This helps the STR 32 respond more quickly to changes in surface unevenness and improve the consistency of surface unevenness determination. Specifically, the average of the most recently processed n signal values ​​is calculated. Then, the a oldest values ​​are discarded and replaced with a newly received values, where a <n, und der neue Durchschnittswert wird berechnet. Dieser Prozess wiederholt sich und die berechneten Durchschnittswerte werden als gleitende Durchschnittswerte bezeichnet. Gewichtungen werden auf diese berechneten gleitenden Durchschnittswerte angewendet, wobei die Gewichtungen in der Richtung der Durchschnittswerte, bezogen auf die älteren empfangenen Signale, exponentiell abnehmen.

[0049] The exponentially weighted moving average filter 46a receives inputs of the processed roll rate data 50a from the absolute value calculator 44a and the moving average sample size 56a (i.e., the value of n) from the data storage 34. The sample size 56a is time-defined and can, for example, contain the signal values ​​received in the preceding 5 seconds. The moving averages are calculated at each time step; for example, if the sampling rate is 5 ms, then the moving average is calculated every 5 ms, every five seconds. The calculated averages are then output by the filter 46a.

[0050] Relay block 48a receives the moving average values ​​and determines whether the measured roll rate signal 50a indicates an uneven or a smooth surface. This process is described in more detail below.

[0051] Fig. Figure 4 shows a procedure 60 performed by the STR 32 to determine whether the surface 28 over which the vehicle 10 is traveling is uneven or smooth. In step 62, the STR 32 of the processor 30 receives the measured driving attribute data 50a, 50b, 50c from the sensors 16 in the form of roll rate signals 50a, tilt rate signals 50b, and lift acceleration signals 50c. Typically, the sampling frequency of these signals can be 100 Hz, but any other suitable value can be used.

[0052] The received driving attribute data or signals 50a, 50b, 50c are passed through the bandpass filters 40a, 40b, 40c, 42a, 42b, 42c in step 64, then through the exponentially weighted moving average filters 46a, 46b, 46c in step 66, as described above. In step 68, the relay blocks 48a, 48b, 48c each analyze the respective processed signals for roll rate, pitch rate, and lift acceleration to determine whether they indicate a smooth or uneven surface. This process is now carried out with reference to the Fig. 5 and Fig. 6 described.

[0053] Fig. Figure 5 shows curves of the moving average values ​​70a, 70b, 70c of signals 50a, 50b, 50c as a function of time in the case of a relatively smooth surface. These moving average values ​​are used to determine whether the driving attribute data 50a, 50b, 50c indicate a smooth or uneven surface and are also related to driving attribute parameters 70a, 70b, 70c. In particular, the Fig. 5a, Fig. 5b, Fig. 5c Curves of the processed average value of the roll rate 70a, the average value of the tilt rate 70b and the average value of the lifting acceleration 70c. Fig. Figure 5d shows how the type of surface, as determined by STR 32, changes over time.

[0054] Each of the Fig. 5a, Fig. 5b, Fig. Figure 5c shows a so-called ON threshold value 72a, 72b, 72c. The ON threshold value 72a, 72b, 72c is the value at which it is taken into account that the determined moving average value 70a, 70b, 70c increases from a "smooth" surface to an "uneven" surface. The ON threshold values ​​72a, 72b, 72c for each of the processed signals of roll rate, pitch rate, and lift acceleration are predetermined and stored in data memory 34 for use by relay blocks 48a, 48b, 48c. For example, it can be seen that in the present example, the roll rate signal ON threshold 72a is equal to 0.015, while the pitch rate ON threshold 72b is 0.03 and the lift acceleration ON threshold 72c is 0.4. It can be seen that in each of the Fig. 5a, Fig. 5b, Fig. 5c the moving averages 70a, 70b, 70c remain below their respective ON thresholds 72a, 72b, 72c for the entire duration of approximately 100 seconds. This means that in this case, all three of the received signals 50a, 50b, 50c show a smooth surface over the entire interval shown.

[0055] In contrast to the relatively smooth surface found in the curves of Fig. As shown in section 5, Fig. 6. The equivalent curves of the moving averages 70a, 70b, 70c of the signals 50a, 50b, 50c as a function of time in the case of a relatively uneven surface. The EIN thresholds 72a, 72b, 72c are the same as in Fig. 5. Taking the moving average value of the roll rate 70a in Fig. As an example, in Figure 6a, the moving average value 70a is smaller than the EIN threshold value 72a in the interval from 0 seconds to approximately 25 seconds. Therefore, in the interval between 0 and approximately 25 seconds, the roll rate signal 50a is characteristic of a smooth surface. The moving average value 70a rises above the EIN threshold value 72a by approximately 25 seconds, which means that the roll rate signal 50a has become characteristic of an uneven surface at this point.

[0056] Each of the Fig. 6a, Fig. 6b, Fig. Figure 6c also shows a so-called AUS threshold value 74a, 74b, 74c. The AUS threshold value is the value at which the specified moving average value is assumed to decrease from an uneven surface to a smooth surface. The AUS threshold values ​​74a, 74b, 74c are smaller than their respective ON threshold values ​​72a, 72b, 72c. In particular, the roll rate AUS threshold value 74a is approximately 0.012, while the pitch rate AUS threshold value 74b is approximately 0.025, and the lift acceleration AUS threshold value 74c is approximately 0.35.

[0057] Again using the moving average value for the roll rate 70a as an example, it shows Fig. 6a, that the moving average value 70a decreases below the AUS threshold value 74a at approximately 47.5 seconds, which means that the roll rate signal 50a shows a smooth surface at this point.

[0058] Each OFF threshold 74a, 74b, 74c does not correspond to its respective ON threshold 70a, 70b, 70c, in order to prevent any of the moving averages 70a, 70b, 70c from fluctuating between a smooth surface and an uneven surface. This can be described as signal hysteresis, i.e., the previous moving average 70a, 70b, 70c determines whether the current moving average 70a, 70b, 70c indicates a smooth or uneven surface. Such fluctuations could cause the vehicle's ride height 10 to be raised and lowered multiple times within a short period, which is entirely undesirable. This also takes into account the slight delay in the movement between the raised and lowered positions 22, 24; that is, it is a responsive system to maintain ride comfort. Returning to Fig. In step 68, each of the relay blocks 48a, 48b, and 48c outputs a determination of either "smooth" or "uneven," as described above. In step 69, gate 49 of STR 32 performs an overall determination, based on these outputs, as to whether the surface 28 is determined to be smooth or uneven. In the present embodiment, if any one of the three relay blocks 48a, 48b, or 48c outputs a determination of "uneven," then the surface 28 is determined to be uneven overall, i.e., gate 49 outputs the value 0. Only if all three outputs are "smooth" is the overall determination of the surface 28 determined to be smooth, i.e., gate 49 outputs the value 1.

[0059] The overall determination made by the STR 32 as to whether the surface 28 is smooth or uneven is then used by the processor 30 to determine whether the vehicle ride height should be adjusted. Fig. Figure 7 shows a procedure 90, which is carried out by the processor 30 to determine whether the vehicle ride height should be adjusted. The procedure 90 begins in step 92 with the vehicle 10 in its raised position 22.

[0060] In step 94, the processor 30 determines whether the conditions for speed reduction are met. In particular, the processor 30 receives the speed reduction data from the sensors 16. In the present embodiment, the onboard sensors 16 include a vehicle speed sensor, and the speed reduction data includes the current vehicle speed. The processor 30 also retrieves a predetermined vehicle speed threshold stored in the data memory 34. Specifically, in step 94, the processor 30 determines whether the current vehicle speed is greater than or less than the predetermined high-speed threshold.

[0061] If the current speed is less than the predetermined threshold speed, then the conditions for a speed reduction are not met, meaning that the vehicle ride height should not be adjusted, and the process returns to step 90. If the current speed is greater than the predetermined threshold speed, then the conditions for a speed reduction are met.

[0062] In this case, procedure 90 proceeds to step 96, in which processor 30 determines whether the surface 28 is smooth or uneven. In particular, processor 30's STR 32 determines whether the surface 28 is smooth or uneven according to procedure 60 described above. Fig. 4 is smooth or uneven. More precisely, if one of the moving average values ​​70a, 70b, 70c increases over time from below the ON threshold 72a, 72b, 72c to above the ON threshold 72a, 72b, 72c, it is determined that the surface 28 is uneven and thus the ride height of the vehicle 10 should not be adjusted from its raised position 22 to its lowered position 24, i.e., any attempt at such an adjustment should be prevented. In this case, the process returns to step 94.

[0063] If all of the moving average values ​​70a, 70b, 70c either fall from above the ON threshold 72a, 72b, 72c below the OFF threshold 74a, 74b, 74c, or simply remain below the ON threshold 72a, 72b, 72c, then it is determined that the surface 28 is smooth. When the STR 32 determines that the surface 28 is smooth, the VSS 18 outputs a control signal 38 to the suspension components 20 in step 98. Signal 38 commands the suspension components 20 to decrease the ride height of the vehicle 10 from the raised position 22 to the lowered position 24, as described above. In other words, any adjustment of the vehicle ride height should not be prevented.

[0064] Vehicle 10 then remains in the lowered position 24 until it is determined that the ride height should be raised to the raised position 22. In particular, in step 100, processor 30 checks, in a similar manner to the above, whether the surface 28 is determined to be smooth or uneven.

[0065] If the surface 28 is still determined to be smooth, the processor 30 does not send a control signal to adjust the ride height and returns to step 100 in step 102. If the surface 28 is determined to be uneven, the VSS 18 outputs a control signal 38 to the suspension components 20 in step 104 to raise the vehicle ride height from the lowered position 24 to the raised position 22.

[0066] In the embodiment described above, the surface is determined to be uneven if one of the driving attribute parameters is above the ON threshold; however, in other embodiments, it may be necessary for a certain number of driving height parameters, which may be less than or equal to the total number, to indicate an uneven surface before the overall determination shows that the surface is uneven.

[0067] In the embodiment described above, the vehicle 10 has two ride height positions, i.e., the raised and the lowered positions 22, 24; however, in other embodiments, the vehicle may have more than two ride height positions. In such embodiments, the system can determine the degree of surface unevenness based on which of the sensors provides data indicating an uneven surface. For example, the system can control the suspension components 20 to adjust the ride height to a specific of the three or more positions based on the determined degree of unevenness. For example, the degree of unevenness can be determined to be between 0 and 6, as shown in Fig. 4 shown. The specific value representing the surface unevenness in Fig.The value assigned to 4 depends on which combination of roll, pitch, and lift thresholds was exceeded by the received signals. For example, it becomes apparent that if the roll and lift thresholds are exceeded, but the pitch threshold is not, the processor then outputs the value 2 (instead of simply a binary output corresponding to "smooth" or "rough"). This additional information can be useful in determining which specific ride heights should be suppressed. Furthermore, in a system with more than two ride height positions, one or more of the ride height parameters may have more than one ON threshold, and one or more specific ride heights may be suppressed depending on which of the at least two ON thresholds for a given parameter has been exceeded.

[0068] The vehicle driving attribute data can be measured differently than in the embodiment described above. For example, a single vertical accelerometer can be used to provide vehicle lift data, and two linear accelerometers can be used to provide vehicle roll and tilt data, respectively. It is understood that the driving attribute data can be provided from various configurations of linear and / or rotational accelerometers.

[0069] In the described embodiment, the driving attribute data includes signals from three different sensors; however, signals from any number of sensors can be used. In various embodiments, the driving attribute data can include signals from sensors other than, or in addition to, a roll rate sensor, a tilt rate sensor, and a lift acceleration sensor. For example, the onboard sensors could include 16 sensors to measure any combination of engine speed, steering wheel angle, steering wheel speed, yaw rate, lateral acceleration, wheel speed, vehicle body height relative to a wheel, longitudinal acceleration, and accelerator pedal position. Furthermore, any combination of acoustic, radar, optical, and LiDAR sensors can be used to provide driving attribute data for determining the unevenness or even the specific type of surface the vehicle is traveling over or that lies ahead of the vehicle.These sensors can be sensors already present on the vehicle, for example sensors used to input data into the vehicle's parking assistance system.

[0070] GPS or other navigation system data can be used to determine when the vehicle is approaching or driving over a known "uneven" road surface and, based on this, prevent the vehicle from lowering its ride height. When an uneven road surface is detected, this information can be shared (via wireless signals or other means) with other vehicles.

[0071] The ON and OFF thresholds are calibrated before the system is used. These are based on what a subjective expert considers an "acceptable" level of driving comfort for the driver and front passenger.

[0072] Although the described embodiment includes both ON and OFF thresholds to protect against flickering as described above, various embodiments may include only a single ON / OFF threshold, with moving average values ​​above the ON / OFF threshold indicating an uneven surface and moving average values ​​below the ON / OFF threshold indicating a smooth surface (i.e., there is no signal hysteresis).

[0073] Numerous modifications can be made to the above examples without deviating from the scope of the present invention as defined in the attached claims.

Claims

[1] System for determining whether a vehicle's ride height should be prevented when the vehicle speed exceeds a speed threshold, the system comprising: a processor with one input configured to receive driving attribute data from at least one onboard vehicle driving attribute sensor, wherein the driving attribute data specifies the unevenness of the surface over which the vehicle is traveling; and a data storage device configured to store at least one predetermined driving attribute threshold for the driving attribute sensor or sensors, wherein the processor is configured to calculate a driving attribute parameter depending on the driving attribute data received for the driving attribute sensor or sensors; and wherein the processor is configured to compare the or each calculated driving attribute parameter with the corresponding at least one predetermined driving attribute threshold to determine whether the vehicle is driving on a smooth surface or an uneven surface, and to lower the ride height if the vehicle speed exceeds the speed threshold, unless it is determined that the vehicle is driving on an uneven surface. [2] System according to claim 1, wherein: the processor comprises an electronic processor with an electrical input for receiving the driving attribute data; and The data storage device comprises an electronic storage device that is electrically coupled to the electronic processor and contains instructions stored therein, wherein the processor is configured to access the storage device and execute the instructions stored therein, so that it is operational to calculate the driving attribute parameter or parameters as a function of the received driving attribute data and to compare the calculated driving attribute parameter or parameters with the corresponding at least one predetermined driving attribute threshold to determine whether the vehicle is traveling on a smooth surface or an uneven surface, and to prevent a reduction in ride height when it is determined that the vehicle is traveling on an uneven surface. [3] System according to claim 1 or claim 2, wherein the processor has an output configured to send a control signal to one or more vehicle suspension components depending on the determination of whether a lowering of the vehicle ride height should be prevented. [4] System according to claim 3, wherein the vehicle suspension components include one or more suspension springs, shock absorbers, tires and linkages. [5] System according to any of the preceding claims, wherein the input is configured to receive a current vehicle speed from a vehicle speed sensor, wherein the data storage is configured to store the speed threshold and the processor is configured to retrieve the speed threshold and determine whether the current vehicle speed is greater than the speed threshold. [6] System according to any of the preceding claims, wherein the processor has at least one bandpass filter configured to attenuate the received driving attribute data in order to calculate the driving attribute parameter or parameters. [7] System according to any of the preceding claims, wherein the processor comprises at least one absolute value calculator configured to calculate the absolute value of the received driving attribute data in order to calculate the driving attribute parameter or parameters. [8] System according to any of the preceding claims, wherein the processor has at least one exponentially weighted moving average filter configured to calculate a moving average of the received driving attribute data at predetermined intervals and to assign exponential weights to the calculated moving averages in order to calculate the driving attribute parameter or parameters. [9] System according to any of the preceding claims, wherein the at least one predetermined driving attribute threshold includes an ON / OFF threshold for the sensor or each sensor, wherein a value of the driving attribute parameter or each calculated above the corresponding ON / OFF threshold indicates an uneven surface, and a value of the driving attribute parameter or each calculated below the corresponding ON / OFF threshold indicates a smooth surface. [10] System according to claim 9, wherein the processor determines that a lowering of the vehicle ride height should be prevented if at least one of the calculated driving attribute parameters is above the corresponding ON / OFF threshold. [11] System according to any one of claims 1 to 9, wherein the at least one predetermined driving attribute threshold includes an ON threshold for the or each sensor, wherein a temporal increase of the calculated driving attribute parameter from below the corresponding ON threshold above the corresponding ON threshold indicates an uneven surface. [12] System according to claim 11, wherein the processor determines that a lowering of the vehicle ride height should be prevented if at least one of the calculated driving attribute parameters increases over time above the corresponding ON threshold. [13] System according to claim 11 or claim 12, wherein the at least one predetermined driving attribute threshold includes an OFF threshold for the or each sensor, wherein each OFF threshold is smaller than the corresponding ON threshold, and wherein a temporal decrease of the calculated driving attribute parameter from above the corresponding OFF threshold to below the corresponding OFF threshold indicates a smooth surface. [14] System according to claim 13, wherein the processor determines that the lowering of the vehicle ride height should only not be prevented if each of the calculated driving attribute parameters decreases below the corresponding OFF threshold in time. [15] System according to any of the preceding claims, wherein the driving attribute data includes a measurement of a vehicle roll rate, a vehicle tilt rate and / or a vehicle lift acceleration. [16] System according to one of the preceding claims, wherein the driving attribute data includes a measurement of a vehicle wheel speed and / or a vehicle body height relative to a wheel. [17] System according to one of the preceding claims, wherein the driving attribute data includes radar sensor output data from at least one on-board radar sensor. [18] System according to one of the preceding claims, wherein the driving attribute data includes acoustic sensor output data from at least one on-board acoustic sensor. [19] System according to one of the preceding claims, wherein the driving attribute data are received from at least one sensor in an inertial measurement unit. [20] System according to one of the preceding claims, wherein the driving attribute data are received from at least two on-board vehicle driving attribute sensors and the processor is configured to compare the calculated driving attribute parameters with the corresponding predetermined driving attribute thresholds to determine whether a lowering of the vehicle's ride height to at least one of at least two lowered vehicle ride height positions should be prevented. [21] System according to any of the preceding claims, wherein, when the vehicle ride height has been lowered to a lowered position, the processor is configured to send a control signal to raise the ride height to a raised position when it is determined that the vehicle is traveling on an uneven surface. [22] Method for determining whether a lowering of the ride height of a vehicle should be prevented when the vehicle speed exceeds a speed threshold, the method comprising: Receiving driving attribute data from at least one onboard vehicle driving attribute sensor, wherein the driving attribute data indicates the unevenness of the surface over which the vehicle is driving; Storing at least one predetermined driving attribute threshold for the driving attribute sensor or sensors; Calculating a driving attribute parameter based on the received driving attribute data for the driving attribute sensor(s); and Comparing the calculated driving attribute parameter(s) with the corresponding at least one predetermined vehicle driving attribute threshold to determine whether the vehicle is driving on a smooth or uneven surface, and to lower the ride height if the vehicle speed exceeds the speed threshold, unless it is determined that the vehicle is driving on an uneven surface. [23] Method for determining whether a lowering of the ride height of a vehicle should be prevented, the method comprising the following: Receiving a current vehicle speed from a vehicle speed sensor and vehicle driving attribute data from at least one onboard vehicle driving attribute sensor, wherein the vehicle driving attribute data indicates the unevenness of the surface over which the vehicle is driving; and Determine whether the current vehicle speed is greater than a stored vehicle speed threshold, where, if the current speed is greater than the speed threshold, the procedure further includes: Calculating a driving attribute parameter based on the received driving attribute data for the driving attribute sensor(s); and Comparing each calculated vehicle driving attribute parameter with at least one stored corresponding predetermined vehicle driving attribute threshold to determine whether the surface is uneven or smooth, and wherein, if it is determined that the surface is uneven, the method then comprises sending a control signal to one or more vehicle suspension components to prevent the vehicle's ride height from lowering. [24] Vehicle comprising a system according to any one of claims 1 to 21. [25] Non-volatile, computer-readable storage medium on which instructions are stored which, when executed by one or more processors, cause the one or more processors to execute the method according to claim 22 or 23.

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