Determining the movement information of a vehicle

Abstract

The invention relates to a method for determining the motion information of a vehicle (1), wherein an analog sensor signal (S) is detected by means of a sensor (5). This signal is adjusted as a function of a change in a magnetic field in response to a movement of an associated pulse wheel (3) coupled to the movement of the vehicle. The invention provides that a first digital output signal (A1) is determined from the analog sensor signal (S) as a function of a second digital output signal (A2) to compensate for influencing factors that affect the signal quality of the sensor signal (S). A change in state (Z) of the second digital output signal (A2) is initiated when a current value of the sensor signal (S) exceeds a predetermined minimum hysteresis value (Hmin) compared to an associated relative extreme value (E) of the sensor signal (S).Depending on the state changes (Z) of the second digital output signal (A2), an observation interval (I) of the sensor signal (S) is defined according to a predefined selection criterion, and a maximum hysteresis value (Hmax) is set based on a comparison of extreme values ​​(E) of the sensor signal (S) within the observation interval (I). A state change (Z) of the first digital output signal (A1) is initiated when a current value of the sensor signal (S) exceeds the determined maximum hysteresis value (Hmax) compared to an associated relative extreme value (E) of the sensor signal (S).

Description

[0001] The invention relates to a method for determining movement information of a vehicle. Furthermore, the invention relates to a sensor device for determining movement information of a vehicle. The invention also relates to a computer program and a computer-readable medium, as well as to a vehicle with at least one corresponding sensor device.

[0002] In this case, movement information is, for example, information about a path or distance traveled by the vehicle and / or the speed at which the vehicle is moving. Such information about the state of motion or the movement of a vehicle is required in various vehicle systems. For example, movement information is used in tachographs for speed display or in various driver assistance systems. Various approaches exist in the state of the art for determining or measuring movement information.

[0003] For example, DE 11 2014 000 771 B4 discloses a method and a device for determining a vehicle's motion state using a yaw rate sensor. Two orthogonally aligned yaw rate sensors each acquire a measurement signal, and low-pass filtering is used to determine a vibration signal representative of the vehicle's rotational movements. The measurement signals are then additively superimposed.

[0004] WO 2008 / 092738 A2 discloses a method and device for detecting pulses. Pulses are detected based on a moving average. The average is determined based on a sequence of transformation values, which results from the transformation of a sequence of samples based on a reference sample.

[0005] WO 2014 / 124889 A1 discloses a method and device for determining the motion state of a vehicle using a yaw rate sensor. Depending on a first measurement signal from the yaw rate sensor, a vibration signal representative of the rotational movement of the vehicle is determined using low-pass filtering. Depending on a comparison of the vibration signal with a predetermined threshold value, it is determined whether the vehicle is stationary or moving.

[0006] WO 2010 / 023165 A1 discloses a method and device for determining the motion state of a vehicle using an acceleration sensor. For this purpose, a vibration signal representative of the vehicle's vibrations is determined based on a measurement signal from the acceleration sensor. Depending on a comparison of the vibration signal with at least one predetermined threshold value, it is determined whether the vehicle is stationary or moving.

[0007] WO 2010 / 072508 A1 discloses a sensor arrangement, a tachograph arrangement, and a method for detecting tampering. To configure the sensor arrangement in such a way that tampering in a magnet is detected, the sensor signal is fed to a second comparator of a signal processing device, which compares the sensor signal within a predetermined operating range and initiates a tampering signal if a value of the sensor signal is outside the operating range.

[0008] To determine the movement information, a sensor system for measuring speed or acceleration can be used, which operates on the principle of pulse detection. One possible design for a sensor system for pulse detection is, for example, a sensor that can detect changes in the magnetic field of an associated pulse wheel. The sensor can comprise a pulse generator and is electromagnetically coupled to the pulse wheel. The pulse wheel or flywheel is connected to or attached to a moving or rotating vehicle part.

[0009] For example, the pulse wheel in the transmission can be connected to a drive shaft. Such a pulse wheel is usually disc-shaped with teeth on its outer edge. As the vehicle moves, the ferromagnetic pulse wheel rotates in front of the sensor, causing the teeth to slide past the sensor. The sensor, for example, contains a Hall IC (IC: Integrated Circuit), i.e., a Hall probe with a bias magnet. The sensor operates contactlessly, taking advantage of the fact that the detected magnetic field changes with the movement of the pulse wheel. In particular, the magnetic field in front of a tooth is larger than in front of a tooth gap. The magnetic field is recorded by the sensor as the teeth slide past the sensor and converted into pulses in real time. The resulting sensor signal is available, for example, as an analog electrical signal, such as a voltage signal and / or current signal.

[0010] Depending on the application, the use of such sensors requires specially adapted pulse wheels or sensors. The main challenge lies in the considerable variation in the amplitude and signal shape of the measured magnetic field of the sensor signal based on the magnetic field. In particular, the signal amplitude decreases exponentially with an air gap between the sensor and the pulse wheel. Additionally, factors such as the geometry and tolerances of the pulse wheel and its teeth and gaps, temperature, external magnetic fields, mechanical wear, and gear movement can influence or disrupt the resulting magnetic field and thus the recorded sensor signal.

[0011] From DE 10 2010 064 203 A1 a method and a device for determining a first and a second detection threshold for detecting the presence of teeth or tooth gaps of a position sensor in front of a sensor are known.

[0012] DE 10 2004 029 941 B3 discloses a device and a method for evaluating a sensor signal. The hysteresis of a comparison device is intended to be non-linearly controlled and adaptively adjusted using an amplitude curve.

[0013] A method and a device for operating a pulse detection device are disclosed in DE 10 2009 050 508 A1. The pulse detection device comprises a decision device configured to output a first output signal value on the output side if a digital signal value applied to an input is greater than a predetermined first threshold value, and to output a second output signal value on the output side if the digital signal value applied to the input is less than a predetermined second threshold value.

[0014] DE 102 44 750 A1 discloses a signal processing device for binary processing of a sensor signal. The signal processing device is intended to set a threshold value with a reference to a peak value of a sensor signal and a minimum value thereof, and to output a binary signal based on the threshold value.

[0015] US 2010 / 0 231 202 A1 discloses an apparatus for detecting a passing magnetic article and providing a detector output signal indicative of the passing magnetic article.

[0016] DE 197 01 260 A1 discloses a method for detecting passing magnetic articles, in which detection thresholds are periodically adjusted to changing amplitudes of a magnetic field. The method comprises detecting an ambient magnetic field and generating a voltage, generating threshold voltages, and generating a proximity detector output voltage.

[0017] It is the object of the present invention to improve robustness in pulse detection for determining movement information of a vehicle with a previously described sensor using pulse wheels.

[0018] The problem is solved by the subject matter of the independent patent claims. Advantageous developments of the invention are disclosed by the dependent patent claims, the description, and the figures.

[0019] According to one aspect, the invention relates to a method for determining movement information, in particular path and / or speed information of a vehicle. An analog sensor signal is detected or measured using a sensor. The sensor signal is adjusted as a function of a change in a magnetic field in response to a movement of an associated pulse wheel coupled to a vehicle movement. This means that the pulse wheel is set in motion in response to the vehicle movement. The sensor is electromagnetically coupled to the pulse wheel, so that the movements of the pulse wheel can be measured by the sensor in the form of pulses as the sensor signal. The sensor signal is, for example, a current or voltage signal. As mentioned above, the sensor can, for example, comprise a Hall IC with bias magnets.

[0020] To determine the motion information, a first digital output signal is determined from the analog sensor signal. The first digital output signal is determined as a function of a second digital output signal to compensate for influencing factors that affect the signal quality of the sensor signal. The first output signal is therefore a result signal that is used to evaluate the motion information. The second output signal is an auxiliary signal that can be used to compensate for or at least reduce influencing factors that, as mentioned above, can generate variations in the amplitude and signal shape of the sensor signal.

[0021] The second output signal is preferably used at least indirectly to generate the first output signal. In particular, the second output signal can be used to set or generate parameters that specify the course of the first output signal, in particular a change in state or a state transition. The state transition preferably occurs based on or taking into account the previous state of the respective signal. This means that the signal state is only changed or toggled if this changes the value of the state.

[0022] A state change for the respective digital output signal refers to a change in the progression between at least two predefined states. It is therefore a change in the level of the respective signal. Preferably, there are exactly two states, referred to, for example, as "high" and "low." These can be signal amplitudes that a microcontroller or microprocessor interprets or perceives as a logical 1 ("high") or logical 0 ("low").

[0023] In the present case, it is now provided that a state change of the second digital output signal is set precisely when a current value exceeds a predetermined minimum hysteresis value compared to an assigned relative extreme value of the sensor signal. The state of the second output signal is only changed or toggled when the condition is met. Otherwise, the previous or previous state is retained. This means that the condition for a state change is met precisely when, for example, a difference between the relative or local extreme value and the current value of the sensor signal is greater than the minimum hysteresis value. The minimum hysteresis value is predetermined or constant. For example, the minimum hysteresis value can be predetermined by tests or simulations depending on the relative position of the sensor and the pulse wheel and / or the geometry of the pulse wheel.

[0024] The comparison is based on the relative extreme value. Here and in the following, the relative extreme value refers to a local extreme value that applies to a section or segment of the sensor signal in which the current sensor signal value is located. The respective relative extreme value can, for example, be mapped or specified in a reference signal. The reference signal replicates the sensor signal as a quantized signal. The reference signal follows the local extreme values, i.e., the minimum and maximum values ​​of the sensor signal. Compared to the analog sensor signal, the reference signal is thus a step signal whose plateaus or steps depend on the local extreme values ​​of the sensor signal.

[0025] Depending on the state changes of the second digital output signal, an observation interval for the sensor signal is now defined according to a predefined selection criterion. The observation interval is, in particular, a time window in which the sensor signal is to be monitored or examined more closely. The interval boundaries of the observation interval are specified according to the selection criterion based on the state changes of the second digital output signal.

[0026] Within the observation interval, a maximum hysteresis value is then determined based on a comparison of extreme values ​​of the sensor signal. This means that one or more extreme values, in particular absolute or global, or relative or local extreme values ​​of the sensor signal, can be compared within the observation interval, and the maximum hysteresis value can be calculated from this. For example, the maximum hysteresis value can be calculated based on a difference between the minimum and maximum values ​​of the sensor signal.

[0027] The maximum hysteresis value is thus cyclically adjusted or changed compared to the minimum hysteresis value based on the observation interval. This allows for signal fluctuations in the sensor signal, which may arise due to the internal or external factors mentioned above, to be taken into account.

[0028] The respective hysteresis value is therefore a limit or threshold value that is the maximum permissible value for the difference between the relative extreme value and the current signal amplitude. This difference in value is established primarily on the basis of the principle of hysteresis. This means that the relative extreme values ​​are adjusted in comparison to the signal amplitude. The extreme value in the reference signal therefore only changes with a time delay compared to the actual signal amplitude. The maximum hysteresis value is selected such that it represents a change in the pulse or amplitude of the sensor signal. In comparison, the minimum hysteresis value is selected such that even local extreme values ​​are interpreted as a change in the pulse or amplitude, even if only a signal change has occurred due to external or internal influencing factors.

[0029] Based on the maximum hysteresis value, a state change of the first digital output signal is now triggered precisely when a current value exceeds the determined maximum hysteresis value compared to an assigned relative extreme value of the sensor signal. This means that the condition for the state change of the first digital output signal is only met if the difference between the current signal amplitude and the relative extreme value is greater than the maximum hysteresis value. Only when the condition is met is the state of the first output signal changed or toggled. Otherwise, the previous or previous state remains.

[0030] The first digital output signal, in particular its curve with the state changes, can now be used to calculate or determine the desired movement information. The curve of the first digital output signal changes directly, in particular proportionally, with the vehicle movement. This means that the signal curve simulates the vehicle movement, in particular rotational movements of the vehicle or vehicle parts, such as a crankshaft and / or a wheel. The frequency of the pulses of the first output signal can be used, for example, as a measure of the rotational speed. Based on the detected pulses and with the known design of the pulse wheel, the vehicle movement, in particular a travel distance or a driving speed, can be calculated using the sensor signals.This takes advantage of the fact that the number of teeth on the pulse wheel, and thus the pulses detected by the sensor, are proportional to the distance or distance traveled by the vehicle. The number of pulses per unit of time is proportional to the vehicle speed. The calculation of the actual movement information can be done, for example, in a tachograph or another of the vehicle systems mentioned above.

[0031] By cyclically or continuously adjusting the maximum hysteresis value and calculating the curve of the first output signal based on this, the robustness of pulse detection can be improved. In particular, the internal or external influencing factors mentioned above, such as geometric tolerances or the air gap, can be compensated for, and preferably reduced, by individually adjusting the maximum hysteresis. For example, magnetic field fluctuations from tooth to tooth of the pulse wheel, which arise due to larger manufacturing tolerances and are subject to wear due to functional use, can also be compensated for. The described method also allows the use of pulse wheels that were not originally designed for detecting position and speed information.These include, for example, helical gears, ratchet wheels or other rotating parts with holes or screw heads that cause a change in the magnetic field in the sensor.

[0032] The invention includes embodiments which provide additional advantages.

[0033] According to one embodiment, the maximum hysteresis value is set to the minimum hysteresis value precisely when the comparison of the extreme values ​​shows that the maximum hysteresis value is lower than the minimum hysteresis value, particularly in terms of absolute value. If, however, the calculation result is greater than the minimum hysteresis value, the maximum hysteresis value is set to the calculated result. This ensures that even small signal changes are interpreted as a change in the state of the first output signal.

[0034] According to one embodiment, to determine the maximum hysteresis value, a comparison result of the comparison of the extreme values ​​is weighted with a predetermined weighting factor. For example, the comparison result can be multiplied by the weighting factor. This allows a change in the amplitude of the sensor signal, which causes a change in state in the first output signal, to be particularly easily adapted to the system conditions. The weighting factor can be specified, for example, by system conditions such as the geometry or the installation location of the sensor and the pulse wheel. For example, a value of 0.5 can be used as the weighting factor, which corresponds, for example, to half the amplitude between a maximum and minimum of the sensor signal as a benchmark. Of course, other values ​​for the weighting factor can also be used.

[0035] According to one embodiment, the observation interval is selected according to the selection criterion such that at least one complete pulse of the sensor signal is included in the observation interval. This means that the selection criterion specifies the interval boundaries for the observation interval, particularly depending on the oscillations of the sensor signal. Preferably, the observation interval is continuously shifted. This means that the interval boundaries can be continuously or cyclically updated with the ongoing sensor signal.

[0036] In this context, one embodiment provides that the observation interval according to the selection criterion comprises at least five, preferably immediately consecutive, state changes of the second output signal. This means that the observation interval is an interval in which five or more state changes of the second output signal were detected in series or consecutively. This ensures that a complete pulse of the sensor signal was observed. To update the interval, for example, the first state change in the series can be dropped as soon as a new state change is detected.

[0037] According to one embodiment, comparing extreme values ​​of the sensor signal within the observation interval comprises determining the global extreme values, i.e. the minima and maxima, for each segment of the sensor signal that is assigned to a state of the second digital output signal in the observation interval, and averaging the determined global extreme values ​​to determine the maximum hysteresis value.

[0038] This means that the sensor signal is again divided into segments or sections within the observation interval, and the global extreme values ​​are calculated for each segment. Preferably, exactly one segment or section is assigned or allocated to each state of the second output signal (high or low). However, any other allocation or assignment of the segments is also conceivable. An average is then calculated from the associated extreme values ​​of all segments, resulting in an averaged minimum value and an averaged maximum value for the observation interval. The difference between the averaged values ​​is then calculated and multiplied, for example, by the weighting factor. This yields the value for the maximum hysteresis. Overall, this allows a particularly robust calculation method for the maximum hysteresis value to be implemented.

[0039] In this context, according to one embodiment, the largest global extreme values ​​of the segments are discarded. This means, for example, that the highest maximum and lowest minimum values ​​are determined by comparing all segments with each other and then deleted or not used for calculating the maximum hysteresis value. This has the advantage that outliers in the sensor signal are not included in the calculation. Overall, this allows for better peak robustness.

[0040] In this context, one embodiment provides for a minimum number of global extreme values ​​in the observation interval, particularly for each segment, to be selected depending on the smallest expected duty cycle of a pulse of the sensor signal. For example, if the duty cycle for a typical pulse is 10 percent for low and 90 percent for high, the minimum number is selected as 10 percent of the number of segments. This also ensures that the minimum and maximum values ​​originate from the low and high phases of the pulse when only a few or only one pulse is present in the interval.

[0041] According to one embodiment, during startup operation, the maximum hysteresis value is set equal to the minimum hysteresis value, and the maximum hysteresis value is determined from a difference between the respective current extreme values ​​of the sensor signal until the selection criterion is met. This results in the advantage that the maximum hysteresis value is maximized as quickly as possible, even with slowly increasing or incomplete input signal periods of the sensor signal until the selection criterion is met, i.e., as long as no observation interval has yet been defined. Preferably, the maximum hysteresis value is only set to the new result value of the difference during the calculation if the newly calculated hysteresis value is greater than the original or previous maximum hysteresis value.

[0042] Startup mode refers specifically to sensor operation when, for example, the sensor has just been switched on. It is therefore a switch-on condition that particularly applies if the previous hysteresis value has not been stored in the sensor. Startup mode is particularly suitable when, for example, a sensor without a memory function is used.

[0043] According to one embodiment, during standby mode, a check is performed periodically for each wake-up time to determine whether the sensor signal has a changed signal value compared to a previous wake-up time. Only if the changed signal value is present is the changed signal value added or added to the relative extreme value present at the previous wake-up time. Both positive and negative changes in the sensor signal at the respective extreme value can be taken into account.

[0044] This offers the advantage that the reference signal, and thus in particular the relative extreme values ​​used for comparison, are carried or tracked along with the sensor signal, even when the sensor is operating in standby mode. Standby mode refers in particular to an operation in which the actual useful function of the sensor is temporarily deactivated but can be reactivated at any time and without preparation or a long wait. Standby mode is therefore also referred to as standby mode. Standby mode is preferably implemented such that the sensor takes a measurement at regular intervals, i.e., at predetermined wake-up times.

[0045] For use cases or application situations that may arise during the method and which are not explicitly described here, it may be provided that, in accordance with the method, an error message and / or a request to enter user feedback is issued and / or a default setting and / or a predetermined initial state is set.

[0046] According to one aspect, the invention relates to a sensor device for determining movement information of a vehicle. The sensor device can preferably execute or carry out a method as described above. The sensor device comprises at least one sensor for detecting an analog sensor signal, which is adjusted as a function of a change in a magnetic field in response to a movement of an associated pulse wheel coupled to a vehicle movement. The sensor device also comprises at least one computing unit. The computing unit is preferably designed to execute or carry out the above-mentioned steps for determining the first output signal according to the method.This means that the computing unit is configured to determine a first digital output signal from the analog sensor signal for determining the motion information, and to determine the first digital output signal as a function of a second digital output signal for compensating for influencing factors that affect the signal quality of the sensor signal. Furthermore, the computing unit is configured to adjust a state change of the second digital output signal precisely when a current value exceeds a predetermined minimum hysteresis value compared to an associated relative extreme value of the sensor signal.

[0047] The computing unit is also designed to define an observation interval of the sensor signal depending on the state changes of the second digital output signal according to a predetermined selection criterion and to define a maximum hysteresis value depending on a comparison of extreme values ​​of the sensor signal within the observation interval.

[0048] Finally, the computing unit is configured to initiate a state change of the first digital output signal precisely when a current value exceeds the determined maximum hysteresis value compared to an associated relative extreme value of the sensor signal. The computing unit can, of course, also be used to calculate or determine the motion information from the first digital output signal using known calculation methods or procedures. Alternatively, the computing unit can transmit or forward the first output signal to another vehicle system, for example, as mentioned above, for the calculation.

[0049] In the present case, a computing unit can be understood in particular as a data processing device that contains a processing circuit. To carry out the described steps, the computing unit can provide a processor circuit or microcontroller circuit that has programming or software that includes programs with commands or program instructions that, when the program instructions are executed, cause the processor circuit to carry out an embodiment of the described method. For this purpose, the processor circuit can have at least one microprocessor and / or microcontroller. The program instructions can be stored in a data memory of the processor circuit. The data memory can be designed as a volatile data memory or as a non-volatile data memory, for example as a read-only memory or as a flash memory.

[0050] According to one aspect, the invention also relates to a computer program comprising instructions which cause the aforementioned sensor device to carry out or carry out the method steps, as described above by way of example, for determining the first digital output signal.

[0051] According to one aspect, the invention relates to a computer-readable medium on which the aforementioned computer program is stored. The computer-readable medium can be implemented as a data storage device.

[0052] According to one aspect, the invention relates to a vehicle with a sensor device as described above by way of example. The vehicle also comprises at least one impulse wheel, which is designed to move, in particular to rotate, in response to a vehicle movement. For this purpose, the impulse wheel is attached to a moving vehicle part or a vehicle component, such as a crankshaft, a drive shaft, or a wheel of the vehicle. The vehicle is preferably designed as a motor vehicle, in particular as a motor vehicle such as a passenger car or truck, or as a passenger bus or motorcycle.

[0053] The invention also includes further developments of the sensor device, the computer program, the computer-readable medium, and the vehicle according to the invention, which have features as already described in connection with the further developments of the method according to the invention. For this reason, the corresponding further developments of the sensor device, the computer program, the computer-readable medium, and the vehicle according to the invention are not described again here.

[0054] The invention also includes combinations of the features of the described embodiments.

[0055] An exemplary embodiment of the invention is described below. It shows: Fig. 1 a schematic representation of a vehicle with a sensor device for determining movement information of the vehicle; Fig. 2 a schematic process flow diagram for a method for operating the sensor device; Fig. 3 is a schematic signal waveform diagram for a first digital output signal obtained from the sensor signal of the sensor device; and Fig. 4 a schematic signal waveform diagram for a second digital output signal obtained from the sensor signal of the sensor device.

[0056] The exemplary embodiment explained below is a preferred embodiment of the invention. In the exemplary embodiment, the described components of the embodiment each represent individual, independently considered features of the invention, which also further develop the invention independently of one another and are thus also to be considered as components of the invention, either individually or in a combination other than that shown. Furthermore, the described embodiment can also be supplemented by further features of the invention already described.

[0057] In the figures, functionally identical elements are provided with the same reference numerals.

[0058] Fig. 1 shows a schematic representation of a vehicle 1. The vehicle 1 is designed, for example, as a passenger car. In Fig. 1 shows a side perspective view of the vehicle 1. The vehicle 1 comprises a drive shaft 2, which transmits power between a transmission and the respective driven wheel of the vehicle 1. In order to obtain movement information about the vehicle 1, the vehicle 1 also comprises a sensor device 4. The movement information can, for example, contain speed information v and / or path information w. The movement information thus provides information about the driving speed of the vehicle 1 or the distance or path the vehicle 1 has already traveled.

[0059] The sensor device 4 comprises a sensor 5 and a computing unit 6. The computing unit 6 comprises, for example, one or more microprocessors or microcontrollers and is designed to carry out or perform computing operations. This includes, for example, processing a sensor signal S to determine the desired movement information provided by the sensor 5. To determine the movement information, the sensor 5 is electromagnetically coupled to a pulse wheel 3. In the present exemplary embodiment, the pulse wheel 3 is fastened or attached to the drive shaft 2. It is attached in such a way that the pulse wheel 3 moves when the drive shaft 2 moves. The sensor 5 can detect the movement of the pulse wheel 3 and thus indirectly also the movement of the vehicle 1 via the drive shaft 2 in the form of pulses. The sensor 5 outputs the pulses as a sensor signal S.

[0060] The sensor device 4 can provide a pulse generator for generating a representative position and / or speed signal (sensor signal) that operates based on dynamically adaptive pulse detection. The sensor 5 can be installed or mounted at various locations in the vehicle 1, such as in a vehicle transmission, on the drive shaft 2, or on the axles. The sensor signal S is representative because the detected position and / or speed information is merely proportional to the vehicle position or speed information, as in the present embodiment on the drive shaft 2.

[0061] The following briefly summarizes the functionality of the sensor device 4. For detecting the path and / or speed information, the pulse wheel 3 is attached to the drive shaft 2, for example, in the transmission. The pulse wheel 3 has, as in the embodiment shown in Fig. 1, a disk-shaped configuration with teeth on its outer edge. While the vehicle 1 is moving, the ferromagnetic pulse wheel 3 rotates in front of the sensor 5. A Hall IC with a bias magnet, for example, is installed in the sensor 5. The sensor 5 therefore operates without contact. In particular, the sensor 5 reacts to changes in the magnetic field that occur when the pulse wheel 3, in particular its teeth, move past the sensor 5. This takes advantage of the fact that the magnetic field in front of a tooth is greater than in front of a tooth gap. The magnetic field is detected by the sensor 5 as the teeth slide past the sensor 5 and is converted into pulses in real time via the dynamically adaptive pulse detection and output as a real-time signal. This real-time signal is the sensor signal S, which is present, for example, as an electrical signal, such as a voltage signal.The course of the sensor signal S, i.e., the pulses generated by the movement of the pulse wheel 3, are representative of the vehicle's movement. For example, the distance traveled by the vehicle 1 can be determined based on the number of teeth that have passed the sensor 5. The pulses per unit of time contained in the sensor signal S, for example, indicate a measure of the vehicle's speed. The desired movement information can thus be determined by evaluating the sensor signal S, for example, in the computing unit 6.

[0062] There are certain challenges when acquiring signals using sensor device 4. One challenge, for example, is the considerable variation in the amplitude and signal shape of the measured magnetic field. For example, the amplitude decreases exponentially with an air gap between sensor 5 and pulse wheel 3. Additionally, factors such as the geometry and tolerances of pulse wheel 3 and its teeth and gaps, as well as ambient temperature, external magnetic fields, mechanical wear, and movement of the gear box or drive shaft 2 can lead to fluctuations in the magnetic field and thus in the sensor signal S. These are interference factors or influencing factors that disrupt the signal quality of sensor signal S and can thus lead to errors in the evaluation.

[0063] This article presents a way to ensure more robust and reliable signal acquisition. Fig. 2 shows a schematic process flow diagram for an exemplary method for operating the sensor device 4. The method operates in particular according to the principle of the dynamically adaptive pulse detection mentioned above. Dynamic or also relative because in the method, signal changes in the sensor signal S are evaluated as the input signal for the computing unit 6, without taking an offset into account. This has the advantage that offset fluctuations can be automatically compensated for and that a larger hysteresis for pulse detection can generally be selected. Adaptive because the maximum hysteresis (maximum hysteresis value Hmax) is cyclically optimized to the possible maximum, taking into account further criteria such as the number of inflection points and minimum and maximum values ​​of the sensor signal S.To capture the additional criteria, an internal digital output signal (second digital output signal A2) is generated using a defined minimum hysteresis (minimum hysteresis value Hmin). This allows for adjustment of the maximum hysteresis for jumps to smaller input signal amplitudes and for a primary digital output signal (first digital output signal A1) to be adjusted accordingly. Overall, the goal is to convert the analog sensor signal S into two digital output signals: the first (primary) digital output signal A1 and the second (internal) digital output signal A2.

[0064] An example of how the signal conversion can be implemented in concrete terms is shown in the process steps of the process flow diagram according to Fig. 2. For this purpose, in a step S1, the sensor signal S is first detected by the sensor 5, as described above, in response to the change in the magnetic field when the pulse wheel 3 moves. The method then continues in a step S2. In step S2, the second output signal A2 is determined or generated from the analog sensor signal S. In particular, a change in state of the second output signal A2 is set precisely when a current value exceeds a predetermined, minimum hysteresis value Hmin compared to an assigned relative extreme value E of the sensor signal S. A change in state here means a change in the level or amplitude of the respective signal. For example, the level can change from high to low or vice versa.

[0065] The method then continues in step S3. In step S3, an observation interval I of the sensor signal S is determined according to a predetermined selection criterion depending on the state changes of the second digital output signal A2. Within or in the observation interval I, extreme values ​​of the sensor signal S are then compared, and a maximum hysteresis value Hmax is calculated or determined from the comparison result.

[0066] Based on the maximum hysteresis value Hmax, the profile of the first digital output signal A1 is then determined or set in a step S4 of the method. Specifically, a state change Z of the first output signal A1 is set when a current value exceeds the determined maximum hysteresis value Hmax compared to an assigned relative extreme value E of the sensor signal S.

[0067] In a step S5, the first output signal A1 is now used to calculate or determine the movement information, i.e. the speed information v and / or the path information w.

[0068] Preferably, steps S2 to S4 or S2 to S5 can be performed or executed by the computing unit 6 of the sensor device 4. To perform the computing operations, the computing unit 6 can comprise a corresponding computer program with instructions or program code, the execution of which, with the computing unit 6, performs the desired method steps. The program code can be stored or stored, for example, on a data memory or computer-readable storage medium of the sensor device 4.

[0069] The signal generation of the first and second output signals A1, A2 can be carried out using the embodiments according to Fig. 3 and Fig. 4 will be clarified once again. Based on Fig. 3, the conversion of the sensor signal S into the first output signal A1 can be described. Fig. 3 shows an exemplary signal waveform diagram of the first output signal A1 in response to a change or a waveform of the sensor signal S. The signal waveforms are shown or plotted in a voltage-time diagram (Ut diagram). As in Fig. 3, the state transitions, i.e., the state changes Z of the first output signal A1, are determined based on the current state of the first output signal A1 and the relative extreme values ​​E, i.e., relative maximum and minimum values ​​Max, Min, of the sensor signal S. The sensor signal S is compared with a reference signal R. The reference signal R is a quantized sensor signal generated based on the extreme values ​​E of the sensor signal S occurring over time. This means that the reference signal R tracks the extreme values ​​E of the sensor signal S.

[0070] As in Fig. As shown in Figure 3, the state of the first output signal A1 changes from high to low if the previous output state was high and if the output signal is below the relative maximum value Max minus the maximum hysteresis Hmax. Conversely, the state changes to high if the input signal exceeds the relative minimum value Min plus the maximum hysteresis Hmax. The state change from high to low and vice versa represents the ratio of the gaps and teeth of pulse wheel 3.

[0071] Preferably, the sensor signal S is assigned to the current state of the first output signal A1 in such a way that it corresponds to the natural electrical state when the device is undervoltage (reset condition). This prevents the electrical output signal A1 from toggling the state of the output signal A1 at the operating voltage limit. For this purpose, the pulse generator can be set to a defined state upon activation, for example, to prevent an undefined state from occurring at the pulse generator during startup due to the supply voltage.

[0072] Based on Fig. 4, the conversion of the analog sensor signal S into the second output signal A2 will now be described in more detail. Fig. 4 analogous to Fig. 3 shows the signal curve of the second output signal A2, in response to the sensor signal S. The signal curves are again plotted in a Ut diagram.

[0073] The second output signal A2 is intended to enable the adaptive adjustment of the maximum hysteresis Hmax. The second output signal A2 is therefore not used directly, but rather influences the calculation of the maximum hysteresis value Hmax, which is used to adjust the curve of the first output signal A1.

[0074] The state changes Z of the second output signal A2 are, as in Fig. 4, based on the current state of the output signal A2 and the relative extreme values ​​E, for example, the relative maximum and minimum values ​​Max, Min, of the sensor signal S. For this purpose, the sensor signal S is again compared with the reference signal R as a quantized sensor signal to check whether their difference exceeds the minimum hysteresis value Hmin or not. As shown in Fig. As shown in Figure 4, the state of the second output signal A2 is changed from high to low if the previous state was high and if the sensor signal S is below the relative maximum value Max minus the minimum hysteresis Hmin. Conversely, the state is changed to high if the sensor signal S exceeds the relative minimum value Min plus the minimum hysteresis Hmin. The minimum hysteresis value Hmin is predetermined and can be calculated, for example, by system conditions or through test experiments or simulations.

[0075] The calculation of the maximum hysteresis Hmax is preferably carried out cyclically. This means that the maximum hysteresis value Hmax is calculated adaptively based on the minimum and maximum values ​​Min, Max of the sensor signal S within a cyclic interval, which is also referred to as the observation interval I. The interval limits of the observation interval I are specified by the selection criterion. In the present embodiment according to Fig. 4, the observation interval I is selected in particular such that the second output signal A2 comprises, for example, five immediately consecutive state changes Z1 to Z5. In the present case, at least five output state changes of the second output signal A2 are used as a criterion to ensure that a complete input signal period of the sensor signal S is detected and thus taken into account for the maximum hysteresis Hmax. The maximum hysteresis Hmax is determined, for example, by multiplying the difference between the maximum and minimum values ​​of the sensor signal S in the interval by a predetermined weighting factor. The second output signal A2 is generated using the minimum hysteresis Hmin, which is determined from the smallest possible signal amplitude, preferably multiplied by a further weighting factor within the application family. For example, 0.5 can be selected for the factors.This means that a disturbance may amount to 50 percent of the sensor signal change of the pulse without this being detected, for example, as a change in the state of the respective output signal.

[0076] To prevent individual signal disturbances from influencing the calculation of the maximum hysteresis Hmax, the calculation can be based on the averaged minimum and maximum values ​​B1', B2' of the sensor signal S. For this purpose, the observation interval I can be set as in Fig. 4, be divided into a further n segments B. The number n of segments B can, for example, be selected by the number of states Z1 - Z5 of the second output signal A2 within the observation interval I or can be predetermined. Within the segments B, the maximum and minimum values ​​of the sensor signal S are also determined. In the present exemplary embodiment, the maxima and minima of the segments B are provided with the reference symbols B1 and B2 and are also referred to as segment minimum B2 and segment maximum B1. In order to create particularly good peak robustness, the lowest minimum value and the highest maximum value of the segments B are not used, but discarded. The remaining k lowest minimum values ​​of the remaining segments B (n-1) and the remaining k highest maximum values ​​B1 of the remaining segments B (n-1) are averaged.n is the number of segments B and k is the number of smallest and largest values ​​over which the mean is calculated.

[0077] The minimum number or minimum number k of segment minimum or maximum values ​​B1, B2 to be averaged is preferably selected to approximate the smallest expected duty cycle of a pulse of the sensor signal S. For example, if the duty cycle for a typical pulse is 10 percent low and 90 percent high, k is selected to be 10 percent of n, i.e. the number of segments B. This also ensures that the minimum and maximum values ​​originate from the high and low phases of the respective pulse, even if there are only a few or only one pulse in the observation interval I. The difference between the averaged segment maximum and segment minimum values ​​B1', B2' is then calculated and multiplied, for example, by the weighting factor. This results in the value for the maximum hysteresis Hmax.

[0078] If the maximum hysteresis Hmax results in a value that is smaller than the minimum hysteresis value Hmin, the maximum hysteresis value Hmax is preferably set equal to the minimum hysteresis value Hmin. Otherwise, i.e., if the result is greater than the minimum hysteresis value Hmin, the maximum hysteresis Hmax is set to the calculated result.

[0079] Preferably, the maximum hysteresis should also be maximized particularly quickly during startup or switching on of the sensor device 4. For this purpose, a switch-on condition explained in more detail below is carried out or implemented in a startup mode X of the sensor device 4. After switching on, the maximum hysteresis Hmax is initially set equal to the minimum hysteresis Hmin if the last determined maximum hysteresis value Hmax is not available. This is the case, for example, if the computing unit 6 does not have a memory function, i.e., cannot permanently store the hysteresis value.In order to maximize the maximum hysteresis Hmax as quickly as possible even with slow, incomplete sensor signal periods, the maximum hysteresis Hmax is calculated from the difference between the maximum and minimum sensor signal values ​​times a factor, for example 0.5, provided that the value is greater than the previous maximum hysteresis value Hmax and a complete observation interval I is not yet available.

[0080] The sensor device 4 should also enable operation in which the maximum hysteresis can be maintained or simulated as accurately as possible during standby operation, i.e., when the usual functional function of the sensor device 4 is paused. Thus, pause compensation can be implemented during the standby operation of the sensor device 4. The pause compensation can also be used analogously for temperature compensation. Fig. Figure 3 shows, as an example, the signal curve of the sensor signal S and the reference signal R in a standby mode X. If the signal acquisition in the standby mode X is paused for a longer period of time, a check is carried out to determine whether the sensor signal S has changed. For this purpose, the current value of the sensor signal S at a current wake-up time tx is compared with the previous value of a previous wake-up time tx. If the values ​​differ, the change is added to the relative maximum or minimum Max, Min, i.e., to the relative extreme value E of the reference signal R, depending on the initial state of the respective output signal A1, A2. As shown in Fig. As shown in Figure 3, the change in the sensor signal can have positive or negative values. In particular, a temperature drift in the deactivated state of the sensor device 4 can be compensated for.

[0081] The described method for determining motion information is therefore particularly suitable for pulse detection in a noisy environment. Robust pulse detection is possible even with non-ideal pulse wheels. To achieve this, the following mechanisms are preferably considered: First, a signal-to-noise ratio is cyclically maximized using the maximum hysteresis. In particular, the maximum hysteresis is not tracked if the input pulse is incomplete using the second internal digital output signal A2. This is particularly relevant, for example, in starting or stopping situations, since the first pulse is in the range of seconds due to the vehicle acceleration. With temporal tracking in this case, the maximum hysteresis would be synchronized to a partial pulse, which would lead to incorrect results.In addition, signal jumps to a smaller amplitude can also be detected using a tracking criterion with the minimum hysteresis. The maximum hysteresis can be maximized particularly quickly by recalculating the maximum hysteresis every time the maximum and minimum input values ​​change after power-up, when the maximum hysteresis has not yet been determined. Since the calculation is based on the current state of the output signal, this also prevents the mechanism from freezing.

[0082] Overall, the examples show how a dynamically adaptive position and / or speed sensor can be realized. List of reference symbols 1 vehicle 2 drive shaft 3 Impulse wheel 4 Sensor device 5 Sensor 6 Computing unit A1 first digital output signal A2 second digital output signal B Segment B1 segment maximum B2 segment minimum B1' averaged segment maximum B2' averaged segment minimum E relative extreme value Hmax maximum hysteresis value Hmin minimum hysteresis value I Observation interval Max relative maximum Min relative minimum R reference signal S sensor signal S1 first step S2 second step S3 third step S4 fourth step S5 fifth step t time tx wake-up time U voltage v Speed ​​information w Route information X Start-up mode Z change of state Z1 change of state Z2 change of state Z3 Change of state Z4 Change of state Z5 Change of state

Claims

[1] Method for determining movement information of a vehicle (1), wherein an analog sensor signal (S) is detected by means of a sensor (5), which is adjusted as a function of a change in a magnetic field in response to a movement of an associated pulse wheel (3) coupled to a vehicle movement, characterized bythat a first digital output signal (A1) for determining the movement information is determined from the analog sensor signal (S), wherein the first digital output signal (A1) is determined as a function of a second digital output signal (A2) for compensating for influencing factors that influence the signal quality of the sensor signal (S), wherein a state change (Z) of the second digital output signal (A2) is set exactly when a current value of the sensor signal (S) exceeds a predetermined minimum hysteresis value (Hmin) in comparison to an associated relative extreme value (E) of the sensor signal (S),and depending on the state changes (Z) of the second digital output signal (A2) according to a predetermined selection criterion, an observation interval (I) of the sensor signal (S) is determined and a maximum hysteresis value (Hmax) is determined depending on a comparison of extreme values ​​(E) of the sensor signal (S) within the observation interval (I), and a state change (Z) of the first digital output signal (A1) is set exactly when a current value of the sensor signal (S) exceeds the determined maximum hysteresis value (Hmax) compared to an associated relative extreme value (E) of the sensor signal (S). [2] Method according to claim 1, wherein the maximum hysteresis value (Hmax) is set to the minimum hysteresis value (Hmin) if and only if the comparison of the extreme values ​​(E) shows that the maximum hysteresis value (Hmax) is below the minimum hysteresis value (Hmin). [3] Method according to one of the preceding claims, wherein, in order to determine the maximum hysteresis value (Hmax), a comparison result of the comparison of the extreme values ​​(E) is weighted with a predetermined weighting factor. [4] Method according to one of the preceding claims, wherein the observation interval (I) is selected according to the selection criterion such that at least one complete pulse of the sensor signal (S) is included. [5] Method according to claim 4, wherein the observation interval (I) according to the selection criterion comprises at least five consecutive state changes (Z, Z1 - Z5) of the second digital output signal (A2). [6] Method according to one of the preceding claims, wherein the comparing comprises that for each segment (B) of the sensor signal (S) which is assigned to a state of the second digital output signal (A2) in the observation interval (I), the global extreme values ​​(B1, B2) are determined and, in order to determine the maximum hysteresis value (Hmax), the determined global extreme values ​​(B1, B2) are averaged. [7] Method according to claim 6, wherein the absolute values ​​(B1, B2) of the segments (B) which are largest in magnitude are discarded. [8] Method according to at least one of claims 6 or 7, wherein a minimum number of global extreme values ​​(B1, B2) in the observation interval (I) is selected as a function of the smallest expected duty cycle of a pulse of the sensor signal (S). [9] Method according to one of the preceding claims, wherein in a start-up operation the maximum hysteresis value (Hmax) is set equal to the minimum hysteresis value (Hmin) and the maximum hysteresis value (Hmax) is determined from a difference between the respective current extreme values ​​(E) of the sensor signal (S) until the selection criterion is met. [10] Method according to one of the preceding claims, wherein in a standby mode (X) it is checked at periodic intervals for each wake-up time (tx) whether the sensor signal (S) has a changed signal value compared to a previous wake-up time (tx), and the changed signal value is added to the relative extreme value (E) present at the previous wake-up time (tx). [11] Sensor device (4) for determining movement information of a vehicle (1), comprising: at least one sensor (5) for detecting an analog sensor signal (S) which is adjusted as a function of a change in a magnetic field in response to a movement of an associated pulse wheel (3) coupled to a vehicle movement, characterized bya computing unit (6) which is designed to: determine a first digital output signal (A1) from the analog sensor signal (S) for determining the movement information, and to determine the first digital output signal (A1) as a function of a second digital output signal (A2) for compensating for influencing factors that influence the signal quality of the sensor signal (S), wherein the computing unit (6) is further designed to set a state change (Z) of the second digital output signal (A2) precisely when a current value of the sensor signal (S) exceeds a predetermined minimum hysteresis value (Hmin) compared to an associated relative extreme value (E) of the sensor signal (S),and depending on the state changes (Z) of the second digital output signal (A2) according to a predetermined selection criterion, to determine an observation interval (I) of the sensor signal (S) and to determine a maximum hysteresis value (Hmax) depending on a comparison of extreme values ​​(E) of the sensor signal (S) within the observation interval (I), and to set a state change (Z) of the first digital output signal (A1) precisely when a current value of the sensor signal (S) exceeds the determined maximum hysteresis value (Hmax) compared to an associated relative extreme value (E) of the sensor signal (S). [12] Computer program comprising instructions which cause the sensor device (4) according to claim 11 to carry out the method steps according to at least one of claims 1 to 10 for determining the first digital output signal (A1) when the computer program is executed with the computing unit (6). [13] A computer-readable medium on which the computer program according to claim 12 is stored. [14] Vehicle (1) with at least one sensor device (4) according to claim 11 and at least one pulse wheel (3) which is designed to move in response to a vehicle movement.

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