SYSTEM AND METHOD FOR IDENTIFYING A CHANGE IN LOAD OF A COMMERCIAL VEHICLE

Abstract

A system for identifying a change in a load of a commercial vehicle, the commercial vehicle including an electronic stability program with at least one inertial sensor and a control unit for estimating a mass of the commercial vehicle and/or the load, including: a device for querying sensor data of the at least one inertial sensor; and an evaluation unit which is configured to identify the load change if the queried sensor data exceed a variation range, and inform the control unit of the identified load change to allow the load change to be taken into account in the estimation of the mass. Also described are a related commercial vehicle, method, and computer readable medium.

Claims

1-14. (canceled)

15. A system for identifying a change in a load of a commercial vehicle, the commercial vehicle including an electronic stability program with at least one inertial sensor and a control unit for estimating a mass of the commercial vehicle and/or the load, comprising: a device for querying sensor data of the at least one inertial sensor; and an evaluation unit which is configured to identify the load change if the queried sensor data exceed a variation range, and inform the control unit of the identified load change to allow the load change to be taken into account in the estimation of the mass.

16. The system of claim 15, wherein the control unit is configured to carry out the mass estimation based on captured values such as a torque of a drive component, a resulting acceleration or speed, or their changes with time, and wherein the mass estimation includes in particular a learning process which learns the mass by continuous capturing of the values, and wherein the evaluation unit is configured to cause the control unit to reset the previously carried out mass estimation or to weight the values captured before the load change differently after the identification of a load change.

17. The system of claim 15, wherein the control unit is configured to communicate a change in the mass estimation to the evaluation unit, and wherein the evaluation unit is configured to determine and change the variation range based on continuous capturing of sensor data if the variation range is exceeded without a change in the mass estimation.

18. The system of claim 15, wherein the evaluation unit is configured to indicate a load change regardless of its magnitude.

19. The system of claim 15, wherein the evaluation unit is configured to use a magnitude of the detected load change for a classification, and wherein each class corresponds to a certain mass range for the load of the commercial vehicle.

20. The system of claim 19, wherein the evaluation unit is configured to use for the classification a large number of learned or predetermined variation ranges, each corresponding to a mass range.

21. The system of claim 15, wherein the evaluation unit is configured to capture a frequency of variations in the sensor data, for lateral accelerations or rotation rates, and/or their derivate and to take these into account when identifying the load change.

22. The system of claim 15, wherein the commercial vehicle comprises a trailer which has another inertial sensor and provides trailer sensor data via a data connection, and wherein the evaluation unit is configured to evaluate the trailer sensor data to identify or confirm the load change based on this.

23. The system of claim 15, wherein the commercial vehicle and/or a connected trailer has a height-adjustable axle, the height position of which can be determined by a sensor system, and wherein the evaluation unit is configured to take into account a change in the height of the height-adjustable axle during a standstill or during slow travel to identify the load change.

24. The system of claim 15, wherein the control unit is a component of the system and is integrated in a component together with the evaluation unit or is in the form of a separate component.

25. The system of claim 15, wherein the evaluation unit is configured to communicate the load change to a driver of the commercial vehicle.

26. A commercial vehicle, comprising: an electronic stability program with at least one inertial sensor; a control unit for estimating a mass of the commercial vehicle and/or a load; and a system for identifying a change in the load of the commercial vehicle, including: a device for querying sensor data of the at least one inertial sensor; and an evaluation unit which is configured to identify the load change if the queried sensor data exceed a variation range, and inform the control unit of the identified load change to allow the load change to be taken into account in the estimation of the mass.

27. A method for identifying a change in load of a commercial vehicle, the commercial vehicle including an electronic stability program with at least one inertial sensor and a control unit for estimating a mass of the commercial vehicle and/or a load, the method comprising: querying sensor data of the at least one inertial sensor; identifying the load change if the queried sensor data exceed a variation range, and providing confirmation of the identified load change for the control unit so that it takes the load change into account when estimating the mass.

28. A non-transitory computer readable medium having a computer program, which is executable by a processor or data processing unit, comprising: a program code arrangement having program code for identifying a change in load of a commercial vehicle, the commercial vehicle including an electronic stability program with at least one inertial sensor and a control unit for estimating a mass of the commercial vehicle and/or a load, by performing the following: querying sensor data of the at least one inertial sensor; identifying the load change if the queried sensor data exceed a variation range, and providing confirmation of the identified load change for the control unit so that it takes the load change into account when estimating the mass.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 shows an exemplary embodiment for the system for detecting a load change of a commercial vehicle.

[0033] FIG. 2 illustrates the detection of a load change based on a variation range of the captured acceleration value according to exemplary embodiments.

[0034] FIG. 3 illustrates a possible learning process for determining the tolerable maximum variation range according to further exemplary embodiments.

[0035] FIG. 4 shows an exemplary embodiment for determining the mass M of the vehicle or its load.

[0036] FIG. 5 shows exemplary measurement results for variations of sensor data of the inertial sensor and their changes due to a load change.

DETAILED DESCRIPTION

[0037] FIG. 1 shows an exemplary embodiment for the system 100 for identifying a load change ΔM of a commercial vehicle 10, wherein the commercial vehicle 10 has an electronic stability program (ESP) with at least one inertial sensor 50. In addition, the commercial vehicle 10 comprises a control unit 150 which is configured to estimate a mass M1, M2 of the commercial vehicle and/or a mass M1, M2 of a load of the commercial vehicle. The mass M1, M2 may refer to the total mass of the commercial vehicle or only to the load (total mass less the unladen mass). The system 100 comprises a device 110 for querying sensor data of at least one inertial sensor 50. In addition, the system comprises an evaluation unit 120 which is configured to determine the load change ΔM if the sensor data queried exceed a maximum variation range ΔA.

[0038] The control unit 150 is informed about a detected load change ΔM, for example via a corresponding data connection 12, so that the control unit 150 can take into account the load change ΔM when estimating the mass M1, M2. The control unit 150 and the evaluation unit 120 can be different components of the vehicle 10. According to further exemplary embodiments, however, it is also possible that the control unit 150 and the evaluation unit 120 are formed within a single vehicle component. Thus, they can be implemented in the form of software in a control unit.

[0039] The inertial sensor 50 in the exemplary ESP unit may be, for example, a three-axis inertial sensor, which, for example, independently captures three different acceleration values: Ax (along the longitudinal direction of the vehicle), Ay (along the transverse direction of the vehicle), Az (along the vertical direction) or corresponding rotation rates around the corresponding spatial directions. It is also possible that not only one inertial sensor 50 is present, but a number of inertial sensors are present in the vehicle 10 to independently capture the acceleration values and/or rotation rates along the x-axis (Ax) or the y-axis (Ay) or the vertical z-axis (Az) or rotation rates around these axes. The x-axis, for example, is the axis parallel to a normal direction of travel of the vehicle, while the y-axis is perpendicular to it in the horizontal plane.

[0040] However, the invention should not be limited to certain inertial sensors 50 as long as at least one acceleration value and/or one rotation rate A can be measured, which changes when a load change ΔM occurs. In the following, multiple acceleration values or rotation rate values A are often mentioned, although the invention is not to be limited to this.

[0041] As an example, FIG. 1 shows on the left the case in which the commercial vehicle 10 has a trailer on which no container has yet been placed and the commercial vehicle has the mass M1. On the right, the case is shown after loading the container on, so that the mass M2 (>M1) has increased. The loading itself is generally associated with vibrations or deflections in the acceleration values/rotation rates A. In addition, the resting value of the acceleration values/rotation rates A may also be shifted after loading since the center of mass of the load will not be exactly central under real conditions and the acceleration due to gravity is always acting.

[0042] The acceleration values or rotation rates A may be measured in an idle state of the vehicle 10 or are continuously monitored in order to be able to detect changes immediately. The idle state (standstill) of the vehicle 10 can be determined, for example, by control electronics of the vehicle 10. It is understood that during the movement of the vehicle 10 a large number of acceleration values/rotation rates A occur, which could falsify the determination of the load change ΔM, so that the measurement of the acceleration values/rotation rates A may be carried out at a standstill.

[0043] FIG. 2 illustrates the detection of a load change ΔM based on a variation range ΔA1, ΔA2 of the captured acceleration value A according to the exemplary embodiments. Although accelerations are captured here as an example, it goes without saying that rotation rates can also be captured and evaluated. FIG. 2 shows acceleration values A as a function of time t, as they are captured by the inertial sensor 50 when the vehicle 10 is at a standstill. It can be discrete or continuous capturing of acceleration values A, wherein measurements during successive standstill periods can also be taken into account.

[0044] The captured acceleration variations initially vary between a minimum value A1 and a maximum value A2 with a tolerable variation range ΔA1. Such variations can have a variety of causes. For example, a passing vehicle, wind or other sources of vibration can be detected by the inertial sensor 50. The individual values (see crosses) which have been combined into a curve represent different measurements at different points in time t or include at least piecemeal periods of time recorded with the vehicle 10 at a standstill.

[0045] At a time t1 there is a sudden jump of the acceleration value A and at times t>t1 the acceleration values A vary between a maximum value A4 (>A2) and the minimum value A1 or a higher value A3. For times t>t1, multiple values for the acceleration values can be measured, which now belong to a second load state (for example for the mass M2 from FIG. 1). The acceleration values A are measured again in an idle state of the vehicle 10.

[0046] According to exemplary embodiments, exceeding the variation range ΔA1 is an indication of a load change ΔM. The evaluation unit 120 will therefore inform the control unit 150 that there has been a (potential) mass change ΔM. The control unit 150 can then use this information to determine the mass again or to interrupt the previous learning process and start again (e.g. by resetting the memory).

[0047] Exceeding the variation range ΔA1 could also be an outlier which does not correspond to a load change ΔM. To take this into account, the consequential values for acceleration A can be taken into account. At these values it can be determined how likely a load change ΔM was. If the new variations, as shown in FIG. 2A, are adjusted to a larger or shifted variation range ΔA2 (for example between A4 and A3) or multiple strong deflections have been detected, then it is most likely a load change ΔM. However, if only a few measurements are outside the old variation range ΔA1 and do not significantly exceed it, it may only be a statistical outlier value, which is most likely not associated with a load change. From the consequential behavior of the curve A=A(t), a correlation can thus be determined as to how likely it is that a load change ΔM has taken place.

[0048] This probability can be used to weight the previous values differently during the mass determination (in the learning process) in the control unit 150. If the probability is close to 1 (as in FIG. 2A), then the memory can be erased in the learning process of the mass determination. Otherwise, these values can be weighted less strongly to take into account the uncertainty of what really happened at time t1.

[0049] In principle, a certain variation range ΔA can be defined for each mass. Therefore, the variation range ΔA can be defined as a continuous function of the mass M. But then it is often difficult to treat outliers correctly because the probability of whether it is an outlier or not is then difficult to decide. In addition, minor mass changes (for example ΔA in a range of 0.2 m/s.sup.2) can be tolerable and do not indicate a load change ΔM. It is therefore advantageous to divide the potential mass changes ΔM into classes, so that only when a certain minimum mass change (for example of 1 tonne or 4 tonnes) is exceeded is a load change detected and forwarded accordingly.

[0050] Advantageous exemplary embodiments therefore use a classification of the load of the commercial vehicle 10. The load can be divided into different load classes. Such load classes may include, for example, a load from 0 to 3 tonnes, from 3 to 6 tonnes, from 6 to 9 tonnes, etc. or other ranges (for example in increments of 2 tonnes or 4 tonnes or 5 tonnes), so that in the determination of the variation range ΔA a separate variation range is defined only for each class, the violation of which constitutes an indication of a load change ΔM. Only when these limits are more or less permanently violated is a more or less strong adjustment of the mass estimate carried out (for example different weighting of the earlier measurement results).

[0051] If there is a complete reset of the mass estimate in the control unit 150, the mass determination is then carried out again, with new valid values for the vehicle 10 after the load change.

[0052] According to further exemplary embodiments, a potential load change ΔM can also be output to the driver, who can then confirm it or not. In this case, the mass estimate in the control unit 150 can be reset and the memory of the learning process can be erased or at least weighted differently. If no confirmation is given, the learning process of the mass M and/or the variation range ΔA can be continued.

[0053] FIG. 3 illustrates a possible learning process for determining the tolerable variation range ΔA, in the event of the violation of which a load change is displayed and, for example, a corresponding signal is sent to the control unit 150. According to exemplary embodiments, the variation range ΔA is not fixed, but is optimized in a learning process. However, an initial value can be specified. The system 100 can thus determine (learn) or improve the tolerable variation range ΔA itself.

[0054] The inertial sensor 50 records a variety of acceleration values/rotation rates A in the idle state, which have a certain variation range ΔA1, for example between a lower value A1 and an upper value A2 (for example, for the x component of the acceleration A). As long as the load state does not change, the variation range will have a value ΔA1, which is typical for the vehicle 10, the ESP unit used, the place of use of the vehicle, etc. For this purpose, a presetting can first be used, which according to the exemplary embodiments can be changed by a learning process or adapted to the specific conditions (in particular to the vehicle). However, it is also possible that the control unit 150 transmits a current load state or a determined change in the mass M to the evaluation unit 120.

[0055] At the time t0 an exemplary deflection occurs for the acceleration/rotation rate A, which is outside this range ΔA1. Subsequently, multiple acceleration values/rotation rates are measured at the times t2, t3, which also have a greater value than the previously measured variation range ΔA1. If such an increased variation range ΔA1 does not correlate with a load change, these values are used to correct the permissible variation range ΔA1 in an idle state for the given load. Apart from a specific notification by the control unit 150, such a load change ΔM can be assumed if the acceleration values/rotation rates A are significantly above the old limit value A2 (for example exceed this by more than 100%).

[0056] The evaluation unit 150 can send a corresponding signal to the control unit 150 in response to the exceedance at time t0, wherein the control unit 150 checks in a subsequent mass determination whether there have been significant changes to the previously measured magnitudes for the mass M. If not, the increased variation at time to can be used to correct the variation range ΔA1. However, if the control unit 150 also detects a significantly increased mass at the subsequent time, the increased acceleration value/the increased rotation rate A at time t0 is probably due to a load change ΔM. Thus, a learning process for the determination of an optimal variation range ΔA of the acceleration value/the rotation rate A in the idle state of the vehicle is set in motion, which may be carried out, for example, for a certain time or permanently, in order to optimize the tolerable variation range ΔA of the captured acceleration value (or the captured rotation rate) A.

[0057] According to further exemplary embodiments, the decision as to whether there was a change in mass ΔM at the time t0 can also be determined on the basis of lift axle positions. In commercial vehicles, for example, the axles can often be moved vertically, for example to make it easier to couple a trailer. This vertical position can be measured, for which appropriate sensors are available. If there has been a load change ΔM, such a load change ΔM can also manifest itself in a change in position of such a moving axle. These sensors can communicate such a vertical change in position, so that according to the exemplary embodiments this information is used to indicate or refute a mass change ΔM at time to.

[0058] With further exemplary embodiments, it is also possible to directly measure the vertical acceleration Az (or the corresponding rotation rate) (for example, using a separate sensor or a 3-axis inertial sensor). If a minimum deflection is detected for this value, this is a clear indication of a load change ΔM, which according to the exemplary embodiments is used to accelerate the mass determination.

[0059] FIG. 4 shows an exemplary embodiment for determining the mass M of the vehicle 10 or its load. For this purpose, a torque D of a vehicle component (for example a driven wheel) can be measured and related to an acceleration a which the vehicle experiences in response to this torque. It is understood that according to the laws of physics, an acting torque D exerts a force on the vehicle 10 and thus leads to an acceleration a.

[0060] In the ideal case, there is a linear relationship between the two quantities, wherein the mass M of the commercial vehicle 10 corresponds to the gradient. However, under real conditions, strictly speaking such a linear relationship does not occur, since friction effects occur, which are usually a function of the speed of the vehicle 10. These are for example frictional forces on the road or frictional forces of the rotating components and are a function of the speed. Therefore, the measured values of the torque D and the resulting acceleration a will be scattered around the linear relationship. From a large number of measurements, however, it is possible to determine or learn the value of the mass M.

[0061] This mass estimation may be integrated in the electronic brake system EBS and is made available to the integrated brake system functions and the ESP (as an estimated vehicle combination mass).

[0062] FIG. 4 shows by way of example how a mass M1 correlates with the measurements marked with circles. A second mass value M2 (>M1) correlates accordingly with the measured values shown with the crosses. In order to determine the mass, a large number of measurements are required, wherein the mass M can be determined or improved more or less accurately by a statistical analysis. This process can be carried out continuously, for example during each acceleration of the commercial vehicle 10.

[0063] Since a load change ΔM can potentially always occur, it is advantageous that older measured values are weighted correspondingly weaker or not taken into account at all. As a result, it is achieved that the system learns the new mass M2 over time after a load change ΔM and can determine the correct mass according to this learning process. Specifically, a so-called RLS algorithm can be used for this learning process, for example, in which a so-called PT1 filter can also be used. In general, however, mass determination based on these algorithms takes a very long time. Certainly, this process can take a very long time. It can lead to the significant safety risk mentioned at the beginning.

[0064] An advantage of the exemplary embodiments is precisely that the load change ΔM can be detected quickly and independently of other sensors and is used to carry out the determination of the mass M faster. Thus, a corresponding history can be erased or weighted differently during the mass determination if, for example, a change in mass ΔM was detected at time t0 or at time t3 and the control unit 150 was caused to take this into account. The mass can then be determined again. By eliminating obviously incorrect measurement values (based on an outdated mass), an accurate result can be achieved more quickly, which is a great advantage of the exemplary embodiments.

[0065] Further exemplary embodiments also relate to a method for identifying a load change. This method may also be computer-implemented, i.e. it may be implemented by instructions stored on a memory medium and capable of performing the steps of the method when running on a processor. The instructions typically include one or more instructions which may be stored in different ways on different media in or peripheral to a control unit (with a processor) which, when read and executed by the control unit, cause the control unit to perform functions, functionalities and operations which are necessary to perform a method according to the present invention.

[0066] FIG. 5 shows exemplary measurement results, which illustrate a first load change at a time of about 100 s and a second load change at a time of about 140 s. These load changes are clearly recognizable in the vibration pattern both in the longitudinal acceleration Ax (top) and in the lateral acceleration Ay (center) as well as in the rotation rate (bottom). In order to be able to better detect the load change, filtering is optionally carried out (see filtered measured variables), which significantly reduces the variation range and can provide better detection signals. Thus, in the case of the exemplary load changes, the variation range of the filtered quantities increases significantly (for example more than doubling), while it is otherwise relatively small.

[0067] The ramp-shaped increase of the longitudinal accelerations Ax between the load changes is a consequence of the readjustment of the air suspension.

[0068] Other advantageous aspects can be summarized as follows:

[0069] A standstill of a vehicle can be reliably detected (for example by revolution rate sensors). Today's commercial vehicles (towing vehicles) usually have ESP sensors for capturing longitudinal acceleration and lateral acceleration as well as the rotation rate in the towing vehicle. According to the exemplary embodiments, at a standstill at least the lateral acceleration and/or the longitudinal acceleration or their derivatives (including of higher order) are observed/captured. A load change ΔM will be indicated in these signals, for example by vibration when a container is loaded or by an offset (especially) in the longitudinal acceleration due to a changed angle of inclination. Fixed values may be specified for the change in the acceleration signal(s) or the variables derived therefrom with which a load change ΔM is identified.

[0070] With further embodiments, these limit values are learned. For this purpose, the maximum is observed during standstill periods. After a successful mass estimate (after the standstill), it is determined with high quality whether the maximum must be assigned to a load change ΔM or to an unchanged load. This is particularly advantageous if different types of vehicles behave differently. In this case, in particular the type of suspension (air or steel suspension) has an influence on the change in the angle of inclination due to the load change ΔM.

[0071] With further embodiments, the lateral acceleration and/or longitudinal acceleration signal, which is captured in the trailer and transmitted to the towing vehicle via a trailer CAN connection according to ISO11992, is determined in the same way (additionally or exclusively) as in the towing vehicle.

[0072] With further embodiments, no digital signal is produced in the event of a load change ΔM (i.e. yes/no) but the magnitude of the load change ΔM is estimated. This is compared by comparing the maximum with a limit which is set or learned offline.

[0073] With further embodiments, not only the maximum, but also the frequency of the sensor data A (lateral acceleration(s) and/or longitudinal acceleration(s) and/or vertical acceleration(s) and/or rotation rate(s)) or their derivatives are used as a decision criterion.

[0074] With further embodiments, in the case of vehicles 10 (towing vehicle and/or trailer) with at least one liftable axle, a change in the lift axle position during a standstill or at slow speed is used as a decision criterion for a load change ΔM. The lift axle position can be determined, for example by a CAN message or, if appropriate, concluded from its revolution rate during slow driving in the case of any existing wheel revolution rate sensors.

[0075] With further embodiments, only load changes ΔM which exceed a certain level are detected. This is because small load changes ΔM have no significant influence on the brake control system and the vehicle dynamics control system.

[0076] The features of the invention disclosed in the description, the claims and the figures may be essential for the realization of the invention, both individually and in any combination.

REFERENCE CHARACTER LIST

[0077] 10 commercial vehicle [0078] 50 inertial sensor [0079] 100 system for identifying the change in load [0080] 110 device for querying sensor data [0081] 120 evaluation unit [0082] 150 control unit [0083] ΔM load change, change in load [0084] A sensor data of the inertial sensor [0085] ΔA maximum variation range of the inertial sensor data (for example acceleration(s) or rotation rate(s)) [0086] A vehicle acceleration [0087] D torque