Vehicle load identification method based on brake pedal displacement

Abstract

The present invention discloses a vehicle load identification method based on brake pedal displacement, comprising: pre-constructing a relationship table between brake pedal opening and deceleration for a preset vehicle model under different loads; obtaining the current vehicle deceleration and the current brake pedal opening within a preset time period; fitting the current vehicle deceleration and the current brake pedal opening to obtain a fitting relationship between the current vehicle deceleration and the current brake pedal opening; obtaining the current vehicle load based on the fitting relationship between the current vehicle deceleration and the current brake pedal opening and the pre-constructed relationship table between brake pedal opening and deceleration for a preset vehicle model under different loads. The vehicle load identification method based on brake pedal displacement of the present invention obtains the vehicle load using brake pedal displacement, the relationship between brake pedal displacement and deceleration is constant, the calculation requires fewer factors to be considered, the vehicle's safety strategy will not affect the vehicle's braking performance, and the calculation result is accurate; the vehicle load is obtained in a low-cost manner.

Description

Technical Field

[0001] The present invention relates to the field of unmanned driving technology, and in particular to a vehicle load identification method based on brake pedal displacement. Background Art

[0002] Vehicle mass is a crucial parameter for commercial trucks, as mass can vary by up to 400%. From the perspective of vehicle autonomous control research, accurately determining vehicle mass can improve vehicle handling stability, driving comfort, and safety. Accurately determining vehicle mass is even more crucial in autonomous vehicle trajectory tracking control research, especially for commercial trucks, as variations in mass directly impact trajectory tracking accuracy.

[0003] Current research in vehicle mass identification can be divided into two categories: the first relies on direct acquisition from road vehicle sensors, a relatively expensive approach. The second involves parameter estimation methods, which utilize information such as longitudinal driving force, longitudinal acceleration, headwind resistance, and tire rolling resistance, along with intelligent algorithms, to accurately estimate vehicle mass online. This is an indirect method for estimating vehicle mass. Notably, the main methods in this second category include adaptive slip observers, least squares methods, and estimation methods based on longitudinal frequency response characteristics. More comprehensive approaches include identification methods that adapt to air resistance variations and methods specifically tailored to electric drive mass identification. However, when using these methods to identify vehicle mass, the accuracy of the vehicle model and the accuracy of the sensors both affect the accuracy of the vehicle model output, and thus the accuracy of vehicle mass identification. Furthermore, since sensors acquire a large number of signals from the vehicle, low sensor accuracy can reduce the accuracy of these signals, further reducing the accuracy of vehicle mass identification.

[0004] Therefore, there is an urgent need for a vehicle load identification method based on brake pedal displacement. Summary of the Invention

[0005] The purpose of the present invention is to provide a vehicle load identification method based on brake pedal displacement to solve the problems in the above-mentioned prior art. The method can obtain the vehicle load by using the brake pedal displacement and obtain the vehicle load in a low-cost manner.

[0006] The present invention provides a vehicle load identification method based on brake pedal displacement, which includes:

[0007] Pre-build a relationship table between brake pedal opening and deceleration under different loads for preset models;

[0008] Obtain the current vehicle deceleration and brake pedal opening within a preset time period;

[0009] Fitting the current vehicle deceleration and the current brake pedal opening to obtain a fitting relationship between the current vehicle deceleration and the current brake pedal opening;

[0010] The current vehicle load is obtained based on the fitting relationship between the current vehicle deceleration and the current brake pedal opening and the pre-built relationship table between the brake pedal opening and deceleration under different loads for preset vehicle models.

[0011] In the vehicle load identification method based on brake pedal displacement, preferably, the pre-established relationship table between brake pedal opening and deceleration for preset vehicle types under different loads specifically includes:

[0012] Establishing a corresponding relationship between brake pedal displacement and the braking force generated by the brake;

[0013] Calculate the vehicle's load;

[0014] Calculate the vehicle deceleration under different loads based on the braking force generated by the brakes and the vehicle load;

[0015] The relationship between brake pedal displacement and vehicle deceleration is obtained based on the corresponding relationship between brake pedal displacement and braking force generated by the brake and the corresponding relationship between braking force generated by the brake under different loads and vehicle deceleration.

[0016] In the above-mentioned vehicle load identification method based on brake pedal displacement, preferably, the calculating of the vehicle load specifically includes:

[0017] Get the speed curve of the vehicle;

[0018] Calculating the real-time deceleration of the vehicle according to the speed curve of the vehicle;

[0019] The load of the entire vehicle is calculated based on the pedal displacement corresponding to the moment of real-time deceleration of the entire vehicle.

[0020] In the above-mentioned vehicle load identification method based on brake pedal displacement, preferably, obtaining the speed curve of the entire vehicle specifically includes:

[0021] For new energy vehicles, the speed curve of the vehicle is obtained based on the output shaft speed of the vehicle motor;

[0022] For fuel vehicles, the speed curve of the vehicle is obtained based on the odometer sensor.

[0023] In the vehicle load identification method based on brake pedal displacement, preferably, the pre-established relationship table between brake pedal opening and deceleration for preset vehicle types under different loads specifically includes:

[0024] Under different loads, the pedal displacement of the vehicle at different times is obtained according to the pedal displacement sensor;

[0025] According to the GPS speedometer, the vehicle speed at different times is obtained, so as to obtain the braking deceleration at different times according to the vehicle speed;

[0026] According to the pedal displacement and braking deceleration of the vehicle at different times under different loads, the corresponding curves of the pedal displacement and braking deceleration of the vehicle under different loads are obtained;

[0027] The interpolation method is used to obtain the corresponding curves of vehicle pedal displacement and braking deceleration under other loads.

[0028] In the above-mentioned vehicle load identification method based on brake pedal displacement, preferably, before obtaining the current vehicle deceleration and the current brake pedal opening within the preset time period, the vehicle load identification method based on brake pedal displacement further includes:

[0029] Get the current brake pedal opening signal;

[0030] Determine whether the current brake pedal opening signal is zero;

[0031] If the current brake pedal opening signal is not zero, the current vehicle deceleration and the current brake pedal opening within the preset time period are obtained;

[0032] If the current brake pedal opening signal is zero, return to the step of obtaining the current brake pedal opening signal.

[0033] In the above-mentioned vehicle load identification method based on brake pedal displacement, preferably, before obtaining the current brake pedal opening signal, the vehicle load identification method based on brake pedal displacement further includes:

[0034] Determine whether the current vehicle speed is greater than a preset speed;

[0035] If the current vehicle speed is greater than the preset speed, the current throttle opening signal and the current vehicle acceleration signal are obtained;

[0036] Determine whether the current vehicle throttle opening and current acceleration are zero;

[0037] If the current vehicle throttle opening and current acceleration are zero, then obtain the current brake pedal opening signal;

[0038] If at least one of the current vehicle throttle opening and the current acceleration is not zero, the process returns to the step of determining whether the current vehicle speed is greater than a preset speed.

[0039] In the above-mentioned vehicle load identification method based on brake pedal displacement, preferably, obtaining the current vehicle load based on the fitting relationship between the current vehicle deceleration and the current brake pedal opening and a pre-established relationship table between the brake pedal opening and deceleration under different loads for preset vehicle types includes:

[0040] Compare the fitted relationship between the current vehicle deceleration and the current brake pedal opening with a pre-built relationship table between the brake pedal opening and deceleration under different loads for a preset vehicle type;

[0041] From a pre-built relationship table of brake pedal opening and deceleration under different loads, select several brake pedal openings and decelerations that are close to the fitted relationship between the current vehicle deceleration and the current brake pedal opening, and use the several loads corresponding to the selected brake pedal openings and decelerations as target loads;

[0042] According to the target loads, the current vehicle load is obtained.

[0043] In the above-mentioned vehicle load identification method based on brake pedal displacement, preferably, obtaining the current vehicle load according to the plurality of target loads specifically includes:

[0044] An average value of several target loads is calculated as the current vehicle load.

[0045] The present invention provides a vehicle load identification method based on brake pedal displacement. The method obtains the current vehicle load according to the fitting relationship between the current vehicle deceleration and the current brake pedal opening and a pre-constructed relationship table between the brake pedal opening and the deceleration of a preset vehicle model under different loads. The vehicle load is obtained using the brake pedal displacement. The relationship between the brake pedal displacement and the deceleration is constant, fewer factors need to be considered in the calculation, and the safety strategy of the vehicle will not affect the vehicle braking performance. The calculation result is accurate. The vehicle load is obtained in a manner that increases the cost of the vehicle as little as possible, while solving the problem that the load of some vehicle models is difficult to measure and the problem that the traditional method is complex and costly to calculate. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described below with reference to the accompanying drawings, in which:

[0047] Figure 1 A flowchart of an embodiment of a vehicle load identification method based on brake pedal displacement provided by the present invention;

[0048] Figure 2 A logic diagram of an embodiment of a vehicle load identification method based on brake pedal displacement provided by the present invention;

[0049] Figure 3 The pedal displacement and vehicle deceleration curves of a certain vehicle model when it is empty and fully loaded. DETAILED DESCRIPTION

[0050] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and is in no way intended to limit the present disclosure, its application, or use. The present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the present disclosure thorough and complete and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of parts and steps, the composition of materials, numerical expressions, and numerical values set forth in these embodiments should be interpreted as being merely exemplary and not as limiting.

[0051] The terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are simply used to distinguish different parts. Terms such as "include" or "comprising" mean that the elements preceding the term include the elements listed after the term, and do not exclude the possibility of also including other elements. Terms such as "upper," "lower," and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0052] In the present disclosure, when a specific component is described as being located between a first component and a second component, there may or may not be an intervening component between the specific component and the first component or the second component. When a specific component is described as being connected to another component, the specific component may be directly connected to the other component without an intervening component, or may not be directly connected to the other component but have an intervening component.

[0053] All terms (including technical or scientific terms) used in this disclosure have the same meaning as those understood by one of ordinary skill in the art to which this disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in, for example, general dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an idealized or highly formal sense, unless explicitly defined herein.

[0054] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0055] like Figure 1 and Figure 2 As shown, the vehicle load identification method based on brake pedal displacement provided by this embodiment includes the following steps during actual implementation:

[0056] Step S1: Pre-build a relationship table between the brake pedal opening and deceleration for a preset vehicle type under different loads.

[0057] The relationship table between the brake pedal opening and deceleration of a preset vehicle model under different loads can be a matrix table or a relationship curve, and the present invention does not make specific limitations on this. In one embodiment of the present invention, a relationship table between the brake pedal opening and deceleration of a preset vehicle model under different loads can be obtained by a theoretical calculation method. The working principle of the braking system is that when the driver needs to brake, he steps on the brake pedal, and the vacuum booster increases the thrust to the master brake cylinder. As the piston in the master brake cylinder moves, the pressure of the brake fluid in the entire brake pipeline gradually increases. At the same time, the brake fluid in the oil reservoir will fill the gap left by the movement of the master brake cylinder piston in time to prevent air from mixing into the brake pipeline system; the brake cylinder (wheel cylinder) in the brake is subjected to the pressure transmitted by the brake pipeline, and gradually presses the two brake linings, so that the friction plate contacts the brake disc to achieve braking. Therefore, there is a corresponding relationship between the pedal displacement and the braking force generated by the brake. The deceleration of the whole vehicle can be calculated from the braking force. Based on this, the corresponding relationship curve between the brake pedal displacement and the deceleration of the whole vehicle can be derived, and this curve will have different characteristics under different vehicle weight conditions. Figure 3 The following are the pedal displacement and vehicle deceleration curves of a certain vehicle model when it is empty and fully loaded. In one embodiment of the vehicle load identification method based on brake pedal displacement of the present invention, step S1 may specifically include:

[0058] Step S11: establishing a corresponding relationship between the brake pedal displacement and the braking force generated by the brake.

[0059] Step S12: Calculate the load of the vehicle.

[0060] In one embodiment of the vehicle load identification method based on brake pedal displacement of the present invention, step S12 may specifically include:

[0061] Step S121: Obtain the speed curve of the entire vehicle.

[0062] In one embodiment of the vehicle load identification method based on brake pedal displacement of the present invention, step S121 may specifically include:

[0063] Step S1211: For new energy vehicles, obtain a speed curve of the vehicle according to the output shaft speed of the motor of the vehicle.

[0064] Step S1212: For a fuel vehicle, obtain a speed curve of the vehicle according to the odometer sensor.

[0065] Step S122: Calculate the real-time deceleration of the vehicle according to the speed curve of the vehicle.

[0066] Step S123: Calculate the load of the vehicle according to the pedal displacement corresponding to the moment of the real-time deceleration of the vehicle.

[0067] The speed curve of the vehicle can be obtained from the output shaft speed of the vehicle motor (new energy vehicles) or the odometer sensor (fuel vehicles), and then the real-time deceleration of the vehicle can be obtained. The data of the corresponding pedal displacement sensor can be used to calculate the load of the vehicle.

[0068] Step S13: Calculate the vehicle deceleration under different loads based on the braking force generated by the brake and the load of the vehicle.

[0069] Step S14: Obtain a relationship between the brake pedal displacement and the vehicle deceleration based on the corresponding relationship between the brake pedal displacement and the braking force generated by the brake and the corresponding relationship between the braking force generated by the brake under different loads and the vehicle deceleration.

[0070] In one embodiment of the present invention, if the PV curve (brake pressure-fluid volume) of the entire vehicle brake caliper has no parameters or some parameters are poorly defined, a test calibration method can be used to determine the relationship between brake pedal opening and deceleration under different loads for a preset vehicle model. In one embodiment of the vehicle load identification method based on brake pedal displacement of the present invention, step S1 may specifically include:

[0071] Step S11 ′: obtaining the pedal displacement of the vehicle at different times according to the pedal displacement sensor under different loads.

[0072] Step S12': obtaining the vehicle speed at different times according to the GPS speedometer, so as to obtain the braking deceleration at different times according to the vehicle speed.

[0073] Step S13 ′: obtaining corresponding curves of the vehicle pedal displacement and the braking deceleration under different loads according to the vehicle pedal displacement and the braking deceleration at different times under different loads.

[0074] Step S14 ′: using interpolation method to obtain corresponding curves of vehicle pedal displacement and braking deceleration under other loads.

[0075] The GPS speedometer can measure the corresponding curve of the vehicle's pedal displacement and braking deceleration. After the empty and fully loaded data are measured, the vehicle's pedal displacement and braking deceleration curves under different load conditions can be obtained according to the interpolation method. The number of tests between empty and fully loaded can also be increased. The more tests are conducted, the more accurate the test results will be.

[0076] Step S2: Obtain the current vehicle deceleration and the current brake pedal opening within a preset time period.

[0077] like Figure 3 As shown, before step S2, the vehicle load identification method based on brake pedal displacement further includes:

[0078] Step S201: Determine whether the current vehicle speed is greater than a preset speed.

[0079] When the vehicle speed is too low, the effectiveness of the brake will deviate. Therefore, it is necessary to ensure that the brake pedal opening is obtained when the current vehicle speed is greater than the preset speed.

[0080] Step S202: If the current vehicle speed is greater than the preset speed, the current throttle opening signal and the current vehicle acceleration signal are obtained.

[0081] Step S203: Determine whether the current vehicle throttle opening and current acceleration are zero.

[0082] Step S204: If the current vehicle throttle opening and the current acceleration are zero, obtain the current brake pedal opening signal.

[0083] Step S205: If at least one of the current vehicle throttle opening and the current acceleration is not zero, return to the step of determining whether the current vehicle speed is greater than the preset speed (ie, return to step S201).

[0084] Step S206: Determine whether the current brake pedal opening signal is zero.

[0085] Step S207: If the current brake pedal opening signal is not zero, the current vehicle deceleration and the current brake pedal opening within a preset time period are obtained.

[0086] Step S208: If the current brake pedal opening signal is zero, return to the step of obtaining the current brake pedal opening signal (ie, return to step S204).

[0087] Step S3: Fitting the current vehicle deceleration and the current brake pedal opening to obtain a fitting relationship between the current vehicle deceleration and the current brake pedal opening.

[0088] Step S4: Obtain the current vehicle load based on the fitting relationship between the current vehicle deceleration and the current brake pedal opening and a pre-built relationship table between the brake pedal opening and deceleration for preset vehicle types under different loads.

[0089] In one embodiment of the vehicle load identification method based on brake pedal displacement of the present invention, step S4 may specifically include:

[0090] Step S41: Compare the fitting relationship between the current vehicle deceleration and the current brake pedal opening with a pre-built relationship table between the brake pedal opening and deceleration for preset vehicle types under different loads.

[0091] Step S42: From the pre-constructed relationship table between brake pedal opening and deceleration under different loads, select several brake pedal openings and decelerations that are close to the fitting relationship between the current vehicle deceleration and the current brake pedal opening, and use the several loads corresponding to the selected brake pedal openings and decelerations as target loads.

[0092] Among them, the closeness here can be understood as the distance, intercept, slope and other parameters between the fitting relationship between the current vehicle deceleration and the current brake pedal opening and the curve corresponding to the pre-constructed brake pedal opening and deceleration relationship table meeting the preset conditions. For example, the distance can be the load corresponding to the first N brake pedal openings and decelerations in order from small to large, such as the first three.

[0093] Step S43: Obtain the current vehicle load according to the target loads.

[0094] Specifically, an average value of several target loads is calculated as the current vehicle load.

[0095] In some embodiments of the present invention, a brake pedal force sensor may be added to calculate the current vehicle load based on the corresponding relationship between pedal force and brake deceleration. In other embodiments of the present invention, the vehicle load calculated based on the corresponding relationship between pedal force and brake deceleration and pedal displacement may be cross-validated with the vehicle load calculated based on the corresponding relationship between brake deceleration to increase the accuracy and stability of the results.

[0096] The vehicle load identification method based on brake pedal displacement provided by the embodiment of the present invention obtains the current vehicle load according to the fitting relationship between the current vehicle deceleration and the current brake pedal opening and a pre-constructed relationship table between the brake pedal opening and deceleration of a preset vehicle model under different loads, and obtains the vehicle load using the brake pedal displacement. The relationship between the brake pedal displacement and the deceleration is constant, and there are fewer factors to be considered in the calculation. In addition, the safety strategy of the vehicle will not affect the vehicle braking performance, and the calculation result is accurate. The vehicle load is obtained in a manner that increases the cost of the vehicle as little as possible, while solving the problem that the load of some vehicle models is difficult to measure and the problem that the traditional method is complex and costly to calculate.

[0097] Thus far, various embodiments of the present disclosure have been described in detail. To avoid obscuring the concept of the present disclosure, some details known in the art have not been described. Based on the above description, those skilled in the art can fully understand how to implement the technical solutions disclosed herein.

[0098] Although some specific embodiments of the present disclosure have been described in detail through examples, those skilled in the art will understand that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. Those skilled in the art will understand that the above embodiments may be modified or some technical features may be replaced with equivalents without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A vehicle load identification method based on brake pedal displacement, characterized in that: include: Pre-build a relationship table between brake pedal opening and deceleration under different loads for preset models; Obtain the current vehicle deceleration and brake pedal opening within a preset time period; Fitting the current vehicle deceleration and the current brake pedal opening to obtain a fitting relationship between the current vehicle deceleration and the current brake pedal opening; According to the fitting relationship between the current vehicle deceleration and the current brake pedal opening and the pre-built relationship table between the brake pedal opening and deceleration of the preset vehicle model under different loads, the current vehicle load is obtained. Before obtaining the current vehicle deceleration and the current brake pedal opening within the preset time period, the vehicle load identification method based on brake pedal displacement further includes: Get the current brake pedal opening signal; Determine whether the current brake pedal opening signal is zero; If the current brake pedal opening signal is not zero, the current vehicle deceleration and the current brake pedal opening within the preset time period are obtained; If the current brake pedal opening signal is zero, return to the step of obtaining the current brake pedal opening signal. Before obtaining the current brake pedal opening signal, the vehicle load identification method based on brake pedal displacement further includes: Determine whether the current vehicle speed is greater than a preset speed; If the current vehicle speed is greater than the preset speed, the current throttle opening signal and the current vehicle acceleration signal are obtained; Determine whether the current vehicle throttle opening and current acceleration are zero; If the current vehicle throttle opening and current acceleration are zero, then obtain the current brake pedal opening signal; If at least one of the current vehicle throttle opening and the current acceleration is not zero, the process returns to the step of determining whether the current vehicle speed is greater than a preset speed.

2. The vehicle load identification method based on brake pedal displacement according to claim 1, characterized in that: The pre-built relationship table between the brake pedal opening and the deceleration under different load conditions for a preset vehicle type specifically includes: Establishing a corresponding relationship between brake pedal displacement and the braking force generated by the brake; Calculate the vehicle's load; Calculate the vehicle deceleration under different loads based on the braking force generated by the brakes and the vehicle load; The relationship between brake pedal displacement and vehicle deceleration is obtained based on the corresponding relationship between brake pedal displacement and braking force generated by the brake and the corresponding relationship between braking force generated by the brake under different loads and vehicle deceleration.

3. The vehicle load identification method based on brake pedal displacement according to claim 2, characterized in that: The calculation of the vehicle load specifically includes: Get the speed curve of the vehicle; Calculating the real-time deceleration of the vehicle according to the speed curve of the vehicle; The load of the entire vehicle is calculated based on the pedal displacement corresponding to the moment of real-time deceleration of the entire vehicle.

4. The vehicle load identification method based on brake pedal displacement according to claim 3, characterized in that: The obtaining of the speed curve of the entire vehicle specifically includes: For new energy vehicles, the speed curve of the vehicle is obtained based on the output shaft speed of the vehicle motor; For fuel vehicles, the speed curve of the vehicle is obtained based on the odometer sensor.

5. The vehicle load identification method based on brake pedal displacement according to claim 1, characterized in that: The pre-built relationship table between the brake pedal opening and the deceleration under different load conditions for a preset vehicle type specifically includes: Under different loads, the pedal displacement of the vehicle at different times is obtained according to the pedal displacement sensor; According to the GPS speedometer, the vehicle speed at different times is obtained, so as to obtain the braking deceleration at different times according to the vehicle speed; According to the pedal displacement and braking deceleration of the vehicle at different times under different loads, the corresponding curves of the pedal displacement and braking deceleration of the vehicle under different loads are obtained; The interpolation method is used to obtain the corresponding curves of vehicle pedal displacement and braking deceleration under other loads.

6. The vehicle load identification method based on brake pedal displacement according to claim 1, characterized in that: The current vehicle load is obtained based on the fitting relationship between the current vehicle deceleration and the current brake pedal opening and a pre-built relationship table between the brake pedal opening and deceleration of a preset vehicle type under different loads, specifically including: Compare the fitted relationship between the current vehicle deceleration and the current brake pedal opening with a pre-built relationship table between the brake pedal opening and deceleration under different loads for a preset vehicle type; From a pre-built relationship table of brake pedal opening and deceleration under different loads, select several brake pedal openings and decelerations that are close to the fitted relationship between the current vehicle deceleration and the current brake pedal opening, and use the several loads corresponding to the selected brake pedal openings and decelerations as target loads; According to the target loads, the current vehicle load is obtained.

7. The vehicle load identification method based on brake pedal displacement according to claim 6, characterized in that: The step of obtaining the current vehicle load according to the target loads specifically includes: An average value of several target loads is calculated as the current vehicle load.

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