Double-electric-drive-axle vehicle drive control method and device based on slip rate

Abstract

The invention relates to a double-electric-drive-axle vehicle driving control method based on the slip rate, and the method is applied to a 6 * 4 vehicle model and comprises the steps that rotating speed signals of a front axle, a middle axle and a rear axle are obtained; according to the rotating speed signals of all the axles, the initial slip rates of the middle axle and the rear axle relative to the front axle are determined; obtaining a vehicle load state and / or current road condition information, wherein the road condition information at least comprises a road slope; based on the vehicle load state and / or the current road condition, the initial slip rates of the middle axle and the rear axle are corrected, and the actual slip rates of the middle axle and the rear axle are obtained; according to the actual slip rates of the middle axle and the rear axle, a drive control strategy is determined, and the drive control strategy at least comprises the torque distribution proportion of the middle axle and the rear axle.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle drive control, and in particular to a slip-rate-based dual-electric drive axle vehicle drive control method and device. Background Art

[0002] Existing pure electric heavy-duty trucks are mainly divided into three categories: the first category is the "oil-to-electric" model, which simply replaces the traditional engine with an electric motor; the second category is the "dual-motor" model, which can optimize the torque output to a certain extent, but due to the coupling of torque at the gearbox input shaft, it is impossible to achieve accurate wheel-end drive force distribution; the third category is the "dual electric drive axle" model, which adopts a distributed drive method, with the middle axle and rear axle each equipped with an independent electric drive system, which has more flexible control potential.

[0003] In terms of slip rate detection, traditional "oil-to-electric" and "dual-motor" models mainly rely on the EBS system to calculate the slip rate by comparing the difference between the wheel-end speed sensor and the front axle speed. However, this method is not completely applicable to dual-electric drive axle models. Since dual-electric drive axle models do not have a drive shaft structure, the middle axle and the rear axle have natural speed inconsistencies in the dual-axle drive state. Therefore, the slip rate obtained by simply comparing the wheel-end speed sensor with the front axle speed is not enough to support the subsequent control system.

[0004] Furthermore, since both the "oil-to-electric" and "dual-motor" 6×4 models have a drive shaft connection, their slip ratio can only calculate the maximum difference. However, the dual electric drive axle model cannot install the connection structure of the inter-axle differential, so the differential control must be achieved through active control, which puts higher requirements on slip detection. Normally, if the slip ratio is too large, the drive torque can be limited through the ASR function to reduce the slip ratio, thereby achieving the purpose of drive anti-skid. However, as an electric drive axle model, if the driving force of the whole vehicle is limited by the minimum value at this time, not only will the optimal driving force be not achieved, but it will also cause the vehicle to have insufficient driving force and weakened climbing ability due to the overall torque limit.

[0005] At present, dual-electric drive axle tractors on the market generally have problems such as insufficient slip rate detection accuracy and insufficient optimization of driving force distribution. Especially on low-adhesion roads or complex working conditions, it is difficult to achieve optimal drive anti-skid control relying solely on traditional slip rate detection methods. In addition, the existing technology also lacks effective utilization of the relative slip rate between the middle axle and the rear axle, which limits the adaptability and performance of the vehicle under different road conditions. Therefore, there is an urgent need for a new method that can detect the slip rate more accurately and effectively apply it to vehicle control to improve the overall performance and safety of pure electric dual-electric drive axle tractors. Summary of the invention

[0006] The invention discloses a driving control method and device for a dual electric drive axle vehicle based on slip ratio, aiming to solve the technical problems existing in the prior art.

[0007] The present invention adopts the following technical solutions:

[0008] In a first aspect, an embodiment of the present invention provides a dual electric drive axle vehicle driving control method based on slip ratio, which is applied to a 6×4 vehicle model, and the method includes:

[0009] Obtain the speed signals of the front axle, middle axle and rear axle;

[0010] According to the rotation speed signals of each bridge, the initial slip ratios of the middle bridge and the rear bridge relative to the front bridge are determined respectively;

[0011] Obtaining vehicle load status and / or current road condition information, where the road condition information at least includes road slope;

[0012] Based on the vehicle load state and / or current road conditions, the initial slip rates of the middle bridge and the rear bridge are corrected to obtain the actual slip rates of the middle bridge and the rear bridge;

[0013] The driving control strategy is determined according to the actual slip rates of the middle axle and the rear axle. The driving control strategy at least includes the torque distribution ratio between the middle axle and the rear axle.

[0014] In some embodiments, the step of obtaining the rotation speed signals of the front axle, the middle axle and the rear axle specifically includes:

[0015] Obtain the speed signal of the front axle;

[0016] Obtain the motor speed signal of the middle bridge and the left and right wheel speed signals of the middle bridge;

[0017] Obtain the motor speed signal of the rear axle and the left and right wheel speed signals of the rear axle.

[0018] In some embodiments, the step of acquiring the speed signals of the front axle, the middle axle and the rear axle also includes the step of filtering the speed signals; the filtering process is configured as median filtering, Kalman filtering, low-pass filtering, Gaussian filtering or wavelet transform filtering.

[0019] In some embodiments, the step of determining the initial slip rates of the middle axle and the rear axle relative to the front axle according to the rotation speed signals of the axles specifically includes:

[0020] According to the motor speed signal of the middle bridge, the left and right wheel speed signals of the middle bridge are calibrated to obtain the middle bridge speed;

[0021] Initial slip rate of middle axle = (front axle speed - middle axle speed) / front axle speed × 100%;

[0022] According to the motor speed signal of the rear axle, the left and right wheel speed signals of the rear axle are calibrated to determine the rear axle speed;

[0023] Initial slip ratio of the rear axle = (front axle speed - rear axle speed) / front axle speed × 100%.

[0024] In some embodiments, the step of correcting the initial slip rates of the middle bridge and the rear bridge based on the vehicle load state and / or the current road condition to obtain the actual slip rates of the middle bridge and the rear bridge specifically includes:

[0025] Determine the load factor based on the vehicle load status;

[0026] Determine the first slip rate correction coefficient corresponding to the current load factor through a preset load-slip rate association model, wherein the load-slip rate association model includes first slip rate correction coefficients corresponding to different load factors;

[0027] The initial slip rates of the middle axle and the rear axle are corrected according to the first slip rate correction coefficient to obtain the actual slip rates of the middle axle and the rear axle.

[0028] In some embodiments, the step of correcting the initial slip rates of the middle bridge and the rear bridge based on the vehicle load state and / or the current road condition to obtain the actual slip rates of the middle bridge and the rear bridge specifically includes:

[0029] Determine the road condition coefficient according to the road slope;

[0030] Determine the second slip ratio correction coefficient corresponding to the current road condition coefficient through a preset road condition-slip ratio association model, wherein the road condition-slip ratio association model includes second slip ratio adjustment coefficients corresponding to different road condition coefficients;

[0031] The initial slip rates of the middle axle and the rear axle are corrected according to the second slip rate correction coefficient to obtain the actual slip rates of the middle axle and the rear axle.

[0032] In some embodiments, in the step of determining the driving control strategy according to the actual slip rates of the middle axle and the rear axle, wherein the driving control strategy at least includes the torque distribution ratio between the middle axle and the rear axle, the following steps are specifically included:

[0033] During active driving, when it is detected that the actual slip rate of any axle exceeds a first preset threshold, the output torque of the drive motor of the axle is reduced, while the output torque of the drive motor of the other axle is increased to maintain the power performance of the vehicle; according to the change of the actual slip rate of the middle axle and the rear axle, the torque distribution ratio of the middle axle and the rear axle is dynamically adjusted;

[0034] During gliding or braking, when it is detected that the actual slip rate of any bridge exceeds the second preset threshold, the energy recovery torque of the bridge is increased, while the energy recovery torque of the other bridge is reduced to maintain the braking performance of the whole vehicle; according to the change of the actual slip rate of the middle bridge and the rear axle, the distribution ratio of the energy recovery torque of the middle bridge and the rear axle is dynamically adjusted.

[0035] In some embodiments, in the step of determining the driving control strategy according to the actual slip rates of the middle axle and the rear axle, wherein the driving control strategy at least includes the torque distribution ratio between the middle axle and the rear axle, the following steps are further included:

[0036] Determine the relative slip rate based on the actual slip rates of the middle axle and the rear axle;

[0037] determining whether the absolute value of the relative slip rate exceeds a third preset threshold;

[0038] When the absolute value of the relative slip ratio exceeds a third preset threshold, differential torque regulation is performed, and for a bridge with a larger slip ratio, a first regulation coefficient is used to reduce its driving torque, and for a bridge with a smaller slip ratio, a second regulation coefficient is used to reduce its driving torque, wherein the first regulation coefficient is greater than the second regulation coefficient;

[0039] The above steps are iteratively performed until the absolute value of the relative slip ratio does not exceed the third preset threshold.

[0040] In some embodiments, the drive control strategy is determined according to the actual slip ratio of the middle axle and the rear axle, and the drive control strategy at least includes the step of determining the torque distribution ratio between the middle axle and the rear axle, and further includes:

[0041] The actual slip rates of the middle and rear axles are continuously monitored, and a fault warning message is generated when the actual slip rate of any axle is detected to be abnormal and exceeds the preset time threshold.

[0042] In some embodiments, it also includes:

[0043] Get the distance and relative speed to the vehicle in front;

[0044] When the actual slip rate of any axle is greater than a fourth preset threshold value, and the distance to the leading vehicle is less than a safety distance threshold value, and / or the relative speed to the leading vehicle is greater than a speed difference threshold value, the vehicle acceleration response sensitivity is reduced, the target following distance to the leading vehicle is increased, the deceleration intensity is adjusted according to the relative speed, and the torque distribution ratio between the middle axle and the rear axle is adjusted;

[0045] When the actual slip rates of all bridges are not greater than the fourth preset threshold, and the distance and relative speed to the leading vehicle are within a safe range, the standard acceleration response sensitivity is gradually restored, and the target following distance to the leading vehicle is restored to the default setting.

[0046] In a second aspect, an embodiment of the present invention provides a dual electric drive axle vehicle drive control device based on slip ratio, which is applied to a 6×4 vehicle model, and the device includes:

[0047] A first acquisition module is used to acquire the speed signals of the front axle, the middle axle and the rear axle;

[0048] An initial slip ratio calculation module is used to determine the initial slip ratios of the middle axle and the rear axle relative to the front axle according to the rotation speed signals of each axle;

[0049] A second acquisition module is used to acquire the vehicle load status and / or current road condition information, where the road condition information at least includes a road slope;

[0050] A correction module, used to correct the initial slip rates of the middle bridge and the rear bridge based on the vehicle load state and / or the current road condition to obtain the actual slip rates of the middle bridge and the rear bridge;

[0051] The control module is used to determine a driving control strategy according to actual slip rates of the middle axle and the rear axle, wherein the driving control strategy at least includes a torque distribution ratio between the middle axle and the rear axle.

[0052] One embodiment of the above invention has the following advantages or beneficial effects:

[0053] The embodiment of the present invention mainly provides a dual-electric drive axle vehicle drive control method and device based on slip rate. By real-time monitoring and calculating the slip rate of the middle axle and the rear axle, combined with the vehicle load status and road condition information, it can realize dynamic adjustment of the dual-bridge drive torque distribution, and provide more valuable reference information for stability control, drive anti-skid control, etc. during vehicle driving. The present invention not only significantly improves the driving efficiency and stability of the vehicle under various complex road conditions and load conditions, but also effectively reduces the risk of wheel slip and vehicle loss of control, greatly improving driving safety. In addition, by reasonably allocating the drive torque of the middle axle and the rear axle, and optimizing the energy recovery strategy by considering the slip rate during braking, energy loss is effectively reduced and the overall energy efficiency of the vehicle is improved.

[0054] Furthermore, the present invention incorporates slip rate information into adaptive cruise control, which not only enhances the safety of following vehicles, but also realizes a more intelligent and comfortable cruising experience. At the same time, by continuously monitoring the slip rate, the system can detect potential vehicle problems early, providing strong support for preventive maintenance, helping to extend the service life of the vehicle and reduce maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments, which constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions explain the present invention and do not constitute improper limitations on the present invention. In the drawings:

[0056] Figure 1 A flow chart of a dual electric drive axle vehicle driving control method based on slip ratio provided by one embodiment of the present invention;

[0057] Figure 2 A partial flow chart of a dual electric drive axle vehicle driving control method based on slip ratio provided by one embodiment of the present invention;

[0058] Figure 3 A structural block diagram of a slip-rate-based dual electric drive axle vehicle drive control device provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in combination with the specific embodiments of the present invention and the corresponding drawings. In the description of the present invention, it should be noted that the term "or" is usually used in the sense of including "and / or", unless the content clearly indicates otherwise. In the following embodiments, "bridge" and "drive bridge" refer to "electric drive bridge".

[0060] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0061] refer to Figure 1 In order to solve the deficiencies in the prior art, the present invention provides a dual-electric drive axle vehicle drive control method based on slip rate. The control method is preferably applicable to pure electric commercial vehicles, and the vehicle is equipped with two drive axles; in some embodiments, the pure electric commercial vehicle is preferably a 6×4 pure electric tractor, including 6 wheels, 4 of which are drive wheels. Specifically, the vehicle has a front axle, a middle axle and a rear axle, the front axle is a steering axle, the middle axle and the rear axle are both drive axles, and each drive axle is equipped with a motor; the power of the middle axle and the rear axle is not specifically limited here, and the specifications and powers of the two can be the same or different.

[0062] like Figure 1 In one embodiment of the present invention, the dual electric drive axle vehicle driving control method based on slip ratio at least includes steps S110 to S150.

[0063] Step S110, obtaining the rotation speed signals of the front axle, the middle axle and the rear axle.

[0064] In one embodiment of the present invention, the speed signal of the front axle is only the wheel-end speed signal, and the speed signals of the middle axle and the rear axle include not only the wheel-end speed signals, but also the speed signals of the motor ends of the middle axle and the rear axle, wherein the wheel-end speed signal is acquired by a wheel-end speed sensor, and the speed signal of the motor end is acquired by a motor speed sensor.

[0065] In one embodiment of the present invention, the two rotation speed sensors mentioned above can both be high-precision Hall-type rotation speed sensors to reduce measurement errors.

[0066] In one embodiment of the present invention, since the slip rates of the left and right wheels of the drive axle may be different, it is necessary to collect the left and right wheel speed signals of the middle axle and the left and right wheel speed signals of the rear axle respectively for the middle axle and the rear axle, so as to adjust the wheel difference of the two drive wheels of the middle axle and the two drive wheels of the rear axle.

[0067] That is, all the signals acquired in this step include the speed signal of the front wheel, the speed signal of the motor of the middle bridge and the speed signal of the left and right wheels of the middle bridge, the speed signal of the motor of the rear bridge and the speed signal of the left and right wheels of the rear bridge, wherein the speed signal of the motor of the middle bridge can be used to calibrate the speed signals of the left and right wheels of the middle bridge so as to obtain more accurate middle bridge speed and middle bridge slip rate, and the speed signal of the motor of the rear bridge is also used to calibrate the speed signals of the left and right wheels of the rear bridge so as to obtain more accurate rear axle speed and rear axle slip rate.

[0068] In one embodiment of the present invention, after obtaining the speed signal of each bridge, each speed signal is filtered and amplified. The filtering method can be selected from median filtering, Kalman filtering, low-pass filtering, Gaussian filtering or wavelet transform filtering. In this embodiment, Kalman filtering is preferably used. This filtering method can integrate the vehicle's speed and acceleration data, and accurately estimate the vehicle's tire speed in real time, which has inherent advantages for vehicle applications.

[0069] In one embodiment of the present invention, the Kalman filter is processed as follows:

[0070] Step S111, establishing a dynamic model of the rotation speed signal. In this embodiment, a first-order linear system is used for approximation.

[0071] Assume that the change in speed conforms to the first-order linear model: x(k+1)=Ax(k)+Bu(k)+w(k), where x(k) is the speed at the kth moment, A and B are model parameters, u(k) is the control input, and w(k) is the process noise.

[0072] Step S112, determining the method and error characteristics of measuring the rotation speed signal.

[0073] For example, the measurement value z(k)=Hx(k)+v(k), where H is the measurement matrix and v(k) is the measurement noise.

[0074] Step S113, giving the initial estimated state x(k) and the initial estimated error covariance P(0).

[0075] The prediction step predicts the state at the next moment based on the system model: x_p(k+1|k)=Ax(k|k), and the prediction error covariance: P_p(k+1|k)=AP(k|k)A^T+Q, where Q is the process noise covariance.

[0076] Step S114, calculating the Kalman gain: K(k+1)=P_p(k+1|k)H^T(HP_p(k+1|k)H^T+R)^(-1), where R is the measurement noise covariance;

[0077] Update state estimate: x(k+1|k+1)=x_p(k+1|k)+K(k+1)(z(k+1)-Hx_p(k+1|k));

[0078] Update error covariance: P(k+1|k+1)=(IK(k+1)H)P_p(k+1|k).

[0079] Repeat the above steps S111 to S114 to continuously filter the speed signal.

[0080] Specifically, since the original signal obtained by the speed sensor usually contains noise, abnormal values ​​or a few spike signals, these abnormal values ​​can be effectively identified and eliminated after filtering to ensure the continuity and reliability of the data. After amplification, it can ensure that the subsequent slip rate calculation and control algorithm can operate based on high-quality and reliable speed signals to improve the accuracy of vehicle control and driving stability.

[0081] Step S120, determining the initial slip rates of the middle axle and the rear axle relative to the front axle respectively according to the rotation speed signals of each axle.

[0082] In one embodiment of the present invention, the left and right wheel speed signals of the middle axle are calibrated according to the motor speed signal of the middle axle to obtain the middle axle speed; the initial slip rate of the middle axle = (front axle speed - middle axle speed) / front axle speed × 100%.

[0083] In one embodiment of the present invention, the rear axle speed is determined by calibrating the left and right wheel speed signals of the rear axle according to the motor speed signal of the rear axle; the initial slip rate of the rear axle = (front axle speed - rear axle speed) / front axle speed × 100%.

[0084] Taking the calibration of the middle bridge speed as an example, after obtaining the motor speed signal and the speed signals of the left and right wheels of the middle bridge, the theoretical wheel-end speed is calculated according to the motor speed and the transmission ratio, and then the errors between the left and right wheels and the theoretical wheel-end speed are calculated respectively, and an acceptable error threshold is defined. If the errors calculated for the left and right wheels are both less than the acceptable error threshold, the average of the left and right wheel speeds is taken as the speed of the bridge. If only one wheel speed is within the error range, this wheel speed can be selected as the bridge speed. If the errors calculated for the left and right wheels are both greater than the acceptable error threshold, the theoretical wheel-end speed is used as the speed of the bridge.

[0085] It should be noted that when the errors between the left and right wheels and the theoretical wheel-end speeds have opposite signs and close absolute values, it means that the vehicle is currently turning. At this time, the average of the left and right wheel speeds can be used as the speed of the bridge; if the errors between the left and right wheels and the theoretical wheel-end speeds are both large and have the same signs, it may indicate severe slippage or wheel suspension. At this time, the theoretical speed should be used.

[0086] In one embodiment of the present invention, the initial slip rates of the left and right wheels of the middle axle relative to the front axle are calculated respectively, and the initial slip rate of the left / right wheel of the middle axle = (front axle speed - middle axle left / right wheel speed) / front axle speed × 100%. The initial slip rates of the left and right wheels of the rear axle are also calculated respectively relative to the front axle, and the initial slip rate of the left / right wheel of the rear axle = (front axle speed - rear axle left / right wheel speed) / front axle speed × 100%.

[0087] Taking the left and right wheels of the middle bridge as an example, when the initial slip rates of the left and right wheels of the middle bridge are different, but the vehicle is not currently in a turning state, the wheel difference compensation of the left and right wheels is performed, and the driving torque is preferably compensated for the wheel on the side with a larger initial slip rate, so as to maximize the grip and avoid affecting the torque distribution of the middle and rear axles.

[0088] Step S130, obtaining the vehicle load status and / or current road condition information, where the road condition information at least includes the road slope.

[0089] In one embodiment of the present invention, there are two ways to determine the vehicle load status. One way is to determine by the load signal fed back by the electronic braking system EBS, and the other way is for the VCU to perform autonomous calculations using a dynamic formula.

[0090] In one embodiment of the present invention, the main logical formula of the load signal fed back by the EBS is F=ma, where F is the braking force, a is the deceleration, F can be equivalently converted into the wheel-side braking force when the brake pressure is known, and a is the deceleration value calculated by the wheel-side speed, so the vehicle mass m=F / a.

[0091] In another embodiment of the present invention, when VCU determines the vehicle load status, it also uses F=ma for calculation. At this time, F is the driving force, a is the acceleration, and F can calculate the driving force of the entire vehicle based on the motor torque signal and the gear signal. a is the acceleration calculated through the front axle speed feedback from the EBS, so the vehicle mass m=F / a.

[0092] Specifically, when the vehicle is powered on, it is static, so F and a are not available for the time being. At this time, the vehicle mass m is initially set according to the default value of half load. When the vehicle starts running and there is an acceleration or deceleration process, the vehicle mass m will be iteratively updated, and the real-time calculated value will be weighted with the historical value, such as m0+m1+m2+…+mx / t=average m. During the iteration process, the m value will become more and more accurate as the vehicle runs.

[0093] In one embodiment of the present invention, the road slope can be calculated based on the vehicle acceleration and angular velocity obtained by the inertial measurement unit IMU, or the slope can be estimated by monitoring the engine torque, power output, accelerator pedal position and other data combined with the vehicle's dynamic model. The specific slope calculation method can adopt any implementation method disclosed in the prior art and is not specifically limited in this embodiment.

[0094] Step S140: Based on the vehicle load state and / or the current road condition, the initial slip rates of the middle bridge and the rear bridge are corrected to obtain the actual slip rates of the middle bridge and the rear bridge.

[0095] In one embodiment of the present invention, the initial slip rate is corrected based on the vehicle load state and the current road condition. When only the vehicle load state is considered, the correction steps are as follows:

[0096] The load coefficient is determined based on the vehicle load status; the first slip rate correction coefficient corresponding to the current load coefficient is determined through a preset load-slip rate association model, wherein the load-slip rate association model includes first slip rate correction coefficients corresponding to different load coefficients; according to the first slip rate correction coefficient, the initial slip rates of the middle axle and the rear axle are corrected to obtain the actual slip rates of the middle axle and the rear axle.

[0097] Specifically, the mass range of the vehicle load is mapped to a preset load coefficient range. For example, the load coefficient is set to 1 to 10 within the mass range of the vehicle load of 10,000 kg to 100,000 kg. At this time, 10,000 kg corresponds to a load coefficient of 1, 15,000 kg corresponds to a load coefficient of 1.5, 20,000 kg corresponds to a load coefficient of 2, and so on. It can be considered as a normalized representation or linear scaling value of the vehicle load mass.

[0098] The preset load-slip ratio correlation model is configured as a lookup table, which records the mapping relationship between different load factors and corresponding slip ratio correction factors. The lookup table is established based on experimental data and theoretical analysis. After obtaining the load factor, the corresponding first slip ratio correction factor is searched or calculated in the load-slip ratio correlation model. If the load factor falls between two preset values, the interpolation method is used to obtain a more accurate first slip ratio correction factor. After obtaining the first slip ratio correction factor, the middle bridge and the rear bridge are corrected respectively. The actual slip ratio = initial slip ratio × first slip ratio correction coefficient.

[0099] When only the current road conditions are considered, the correction steps are as follows:

[0100] The road condition coefficient is determined according to the road surface slope; the second slip rate correction coefficient corresponding to the current road condition coefficient is determined through a preset road condition-slip rate association model, and the road condition-slip rate association model includes second slip rate adjustment coefficients corresponding to different road condition coefficients; according to the second slip rate correction coefficient, the initial slip rates of the middle bridge and the rear axle are corrected to obtain the actual slip rates of the middle bridge and the rear axle.

[0101] During the actual correction process, when it is judged to be an uphill road condition, the slip rate adjustment range is increased to overcome the influence of gravity; when it is judged to be a downhill road condition, the slip rate adjustment range is reduced to adapt to gravity assistance.

[0102] Specifically, the mapping method of the road slope and the road condition coefficient is the same as the mapping method of the vehicle load state and the load coefficient, which will not be repeated here; the preset road condition-slip ratio association model is also configured as a lookup table, which records the mapping relationship between different road condition coefficients and corresponding slip ratio correction coefficients. After obtaining the road condition coefficient, the corresponding second slip ratio correction coefficient is searched or calculated in the road condition-slip ratio association model, and then the middle bridge and the rear bridge are corrected respectively. The actual slip ratio = initial slip ratio × second slip ratio correction coefficient.

[0103] In one embodiment of the present invention, when the load state and the current road condition are considered simultaneously, the actual slip ratio=initial slip ratio×first slip ratio correction coefficient×second slip ratio correction coefficient.

[0104] Step S150, determining a driving control strategy according to actual slip rates of the middle axle and the rear axle, wherein the driving control strategy at least includes a torque distribution ratio between the middle axle and the rear axle.

[0105] In one embodiment of the present invention, during the active driving process, the actual slip rate of the middle bridge and the rear bridge is continuously monitored. When it is detected that the actual slip rate of any bridge exceeds the first preset threshold, the output torque of the driving motor of the bridge is reduced, and the output torque of the driving motor of the other bridge is increased. The increase range should consider keeping the total output torque unchanged or slightly increasing it to maintain the power performance of the whole vehicle; according to the change of the actual slip rate of the middle bridge and the rear bridge, the torque distribution ratio of the middle bridge and the rear bridge is dynamically adjusted. In this embodiment, the specific value of the first preset threshold needs to be determined according to the vehicle characteristics and safety requirements, and is not specifically limited here.

[0106] In one embodiment of the present invention, the accelerator pedal position, brake pedal pressure, vehicle speed change rate and other parameters are used to identify whether the vehicle is in a sliding or braking state. During the sliding or braking process, when the actual slip rate of any bridge is detected to exceed the second preset threshold, the energy recovery torque of the bridge is increased, and the energy recovery torque of the other bridge is reduced. The reduction range should consider keeping the total braking torque unchanged to maintain the braking performance of the whole vehicle; according to the change of the actual slip rate of the middle bridge and the rear bridge, the distribution ratio of the energy recovery torque of the middle bridge and the rear bridge is dynamically adjusted. In this embodiment, the specific value of the second preset threshold needs to be determined according to the vehicle characteristics and safety requirements, and is not specifically limited here.

[0107] In one embodiment of the present invention, the step of adjusting the torque based on the relative slip ratio between the middle axle and the rear axle is further included, as follows:

[0108] According to the actual slip rate of the middle bridge and the rear bridge, the relative slip rate is determined, and the relative slip rate = the slip rate of the middle bridge - the slip rate of the rear bridge;

[0109] Determining whether the absolute value of the relative slip ratio exceeds a third preset threshold value, wherein the specific value of the first preset threshold value needs to be determined according to vehicle characteristics and safety requirements and is not specifically limited here;

[0110] When the absolute value of the relative slip ratio exceeds the third preset threshold, differential torque regulation is performed, and for the bridge with a larger slip ratio, the first regulation coefficient is preferentially used to reduce its driving torque, and for the bridge with a smaller slip ratio, the second regulation coefficient is used to reduce its driving torque, so as to quickly respond to the performance difference between the driving axles, thereby improving the overall performance and safety of the vehicle; wherein, the adjustment rate of the first regulation coefficient to the slip ratio is greater than that of the second regulation coefficient;

[0111] The above steps are iteratively performed until the absolute value of the relative slip ratio does not exceed the third preset threshold.

[0112] In one embodiment of the present invention, step S150 also includes: continuously monitoring the actual slip rates of the middle axle and the rear axle. When it is detected that the actual slip rate of any axle is abnormal and exceeds a preset time threshold, it may indicate tire wear, brake system failure or drive system problem, and fault warning information is generated to remind the driver to perform maintenance inspection.

[0113] refer to Figure 2 In one embodiment of the present invention, steps S161 to S163 are also included as follows:

[0114] Step S161, obtaining the distance and relative speed to the preceding vehicle.

[0115] Specifically, the distance to the preceding vehicle may be measured and determined by a millimeter wave radar or a laser radar; the relative speed to the preceding vehicle may be obtained by continuous distance measurement or directly from the radar system.

[0116] Step S162, when the actual slip rate of any bridge is greater than the fourth preset threshold, and the distance to the front vehicle is less than the safety distance threshold, and / or the relative speed to the front vehicle is greater than the speed difference threshold, reduce the vehicle acceleration response sensitivity, increase the target following distance to the front vehicle, adjust the deceleration intensity according to the relative speed, and adjust the torque distribution ratio between the middle bridge and the rear bridge.

[0117] Specifically, by reducing the proportional relationship between the accelerator pedal position and the actual output torque, the vehicle acceleration response sensitivity can be reduced; further, more torque is tilted toward the bridge with a smaller slip ratio.

[0118] Step S163, when the actual slip rates of all bridges are not greater than the fourth preset threshold, and the distance and relative speed to the leading vehicle are within a safe range, the standard acceleration response sensitivity is gradually restored, and the target following distance to the leading vehicle is restored to the default setting.

[0119] Through the above steps S161 to S163, the adaptive cruise control (ACC) can be combined with the control of the slip rate. The vehicle can provide a more intelligent and comfortable driving experience while ensuring safety, effectively preventing dangerous situations caused by insufficient road adhesion, and optimizing the following performance.

[0120] like Figure 3 In an embodiment of the present invention, a dual electric drive axle vehicle driving control device based on slip ratio is also provided, and the device at least includes:

[0121] The first acquisition module 210 is used to acquire the rotation speed signals of the front axle, the middle axle and the rear axle.

[0122] The initial slip ratio calculation module 220 is used to determine the initial slip ratios of the middle axle and the rear axle relative to the front axle according to the rotation speed signals of each axle.

[0123] The second acquisition module 230 is used to acquire the vehicle load status and / or current road condition information, where the road condition information at least includes the road slope.

[0124] The correction module 240 is used to correct the initial slip rates of the middle bridge and the rear bridge based on the vehicle load state and / or the current road condition to obtain the actual slip rates of the middle bridge and the rear bridge.

[0125] The control module 250 is used to determine a driving control strategy according to actual slip rates of the middle axle and the rear axle. The driving control strategy at least includes a torque distribution ratio between the middle axle and the rear axle.

[0126] It should be noted that the dual electric drive axle vehicle drive control device based on slip ratio and the dual electric drive axle vehicle drive control method based on slip ratio provided in the above embodiments belong to the same concept, and the specific implementation process is detailed in the embodiment of the control method, which will not be repeated here.

[0127] An embodiment of the present invention further provides a pure electric commercial vehicle, which is preferably a 6×4 model with dual electric drive axles. The vehicle is equipped with the above-mentioned dual electric drive axle vehicle drive control device based on slip rate, or the vehicle can implement the above-mentioned dual electric drive axle vehicle drive control method based on slip rate.

[0128] An embodiment of the present invention further provides an electronic device, which includes a memory and a processor, wherein a computer program executed by the processor is stored in the memory, and when the computer program is executed by the processor, the processor executes the dual electric drive axle vehicle drive control method based on slip rate in the foregoing text. Various applications and various data may also be stored in the memory, such as various data used and / or generated by the application. The processor may be a central processing unit (CPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other forms of processing units having data processing capabilities and / or instruction execution capabilities.

[0129] The embodiment of the present invention also provides a computer-readable storage medium, on which a computer program executed by a processor is stored. When the computer program is executed by the processor, the processor executes the slip-based dual electric drive axle vehicle drive control method as described above. Exemplarily, the computer storage medium may include a memory card of a smart phone, a storage component of a tablet computer, a hard disk of a personal computer, a read-only memory (ROM), an erasable programmable read-only memory (EPROM), a portable compact disk read-only memory (CD-ROM), a USB memory, or any combination of the above storage media. The computer-readable storage medium may be any combination of one or more computer-readable storage media.

[0130] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present application to this. Those of ordinary skill in the art may make various changes and modifications therein without departing from the scope and spirit of the present application. All these changes and modifications are intended to be included within the scope of the present application as required by the appended claims.

[0131] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0132] Similarly, it should be understood that in order to streamline the present application and help understand one or more of the various inventive aspects, in the description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the present application should not be interpreted as reflecting the following intention: the claimed application requires more features than the features clearly stated in each claim. More specifically, as reflected in the corresponding claims, the inventive point is that the corresponding technical problem can be solved with features less than all the features of a single disclosed embodiment. Therefore, the claims following the specific embodiment are hereby explicitly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the present application.

[0133] It will be understood by those skilled in the art that, except for mutually exclusive features, all features disclosed in this specification (including the accompanying claims, abstracts and drawings) and all processes or units of any method or device disclosed in this specification may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstracts and drawings) may be replaced by an alternative feature that provides the same, equivalent or similar purpose.

[0134] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A dual electric drive axle vehicle driving control method based on slip ratio, characterized in that: Applied to 6×4 vehicle models, the method comprises: Obtain the speed signals of the front axle, middle axle and rear axle; Determining the initial slip rates of the middle axle and the rear axle relative to the front axle respectively according to the speed signals of the axles; Acquiring vehicle load status and / or current road condition information, wherein the road condition information at least includes a road slope; Based on the vehicle load state and / or current road conditions, the initial slip rates of the middle bridge and the rear bridge are corrected to obtain actual slip rates of the middle bridge and the rear bridge; According to the actual slip ratios of the middle axle and the rear axle, a driving control strategy is determined, and the driving control strategy at least includes a torque distribution ratio between the middle axle and the rear axle.

2. The dual electric drive axle vehicle driving control method based on slip ratio according to claim 1, characterized in that: The step of obtaining the rotation speed signals of the front axle, the middle axle and the rear axle specifically includes: Obtain the speed signal of the front axle; Obtain the motor speed signal of the middle bridge and the left and right wheel speed signals of the middle bridge; Obtain the motor speed signal of the rear axle and the left and right wheel speed signals of the rear axle.

3. The dual electric drive axle vehicle driving control method based on slip ratio according to claim 2, characterized in that: The step of acquiring the speed signals of the front axle, the middle axle and the rear axle also includes a step of filtering the speed signals; the filtering is configured as median filtering, Kalman filtering, low-pass filtering, Gaussian filtering or wavelet transform filtering.

4. The dual electric drive axle vehicle driving control method based on slip ratio according to claim 2, characterized in that: The step of determining the initial slip rates of the middle axle and the rear axle relative to the front axle respectively according to the rotation speed signals of the axles specifically includes: According to the motor speed signal of the middle bridge, the left and right wheel speed signals of the middle bridge are calibrated to obtain the middle bridge speed; Initial slip rate of middle axle = (front axle speed - middle axle speed) / front axle speed × 100%; According to the motor speed signal of the rear axle, the left and right wheel speed signals of the rear axle are calibrated to determine the rear axle speed; Initial slip ratio of the rear axle = (front axle speed - rear axle speed) / front axle speed × 100%.

5. The dual electric drive axle vehicle driving control method based on slip ratio according to claim 4, characterized in that: The step of correcting the initial slip rates of the middle bridge and the rear bridge based on the vehicle load state and / or the current road condition to obtain the actual slip rates of the middle bridge and the rear bridge specifically includes: Determining a load factor based on the vehicle load state; Determining a first slip ratio correction coefficient corresponding to the current load factor through a preset load-slip ratio correlation model, wherein the load-slip ratio correlation model includes first slip ratio correction coefficients corresponding to different load factors; The initial slip rates of the middle axle and the rear axle are corrected according to the first slip rate correction coefficient to obtain actual slip rates of the middle axle and the rear axle.

6. The dual electric drive axle vehicle driving control method based on slip ratio according to claim 4, characterized in that: The step of correcting the initial slip rates of the middle bridge and the rear bridge based on the vehicle load state and / or the current road condition to obtain the actual slip rates of the middle bridge and the rear bridge specifically includes: Determining a road condition coefficient according to the road slope; Determining a second slip ratio correction coefficient corresponding to the current road condition coefficient through a preset road condition-slip ratio association model, wherein the road condition-slip ratio association model includes second slip ratio adjustment coefficients corresponding to different road condition coefficients; The initial slip rates of the middle axle and the rear axle are corrected according to the second slip rate correction coefficient to obtain actual slip rates of the middle axle and the rear axle.

7. The dual electric drive axle vehicle driving control method based on slip ratio according to claim 1, characterized in that: In the step of determining the driving control strategy according to the actual slip ratio of the middle axle and the rear axle, wherein the driving control strategy at least includes the torque distribution ratio between the middle axle and the rear axle, the method specifically includes: During active driving, when it is detected that the actual slip rate of any axle exceeds a first preset threshold, the output torque of the drive motor of the axle is reduced, while the output torque of the drive motor of the other axle is increased to maintain the power performance of the vehicle; according to the change of the actual slip rate of the middle axle and the rear axle, the torque distribution ratio of the middle axle and the rear axle is dynamically adjusted; During gliding or braking, when it is detected that the actual slip rate of any bridge exceeds a second preset threshold, the energy recovery torque of the bridge is increased, while the energy recovery torque of the other bridge is reduced to maintain the braking performance of the whole vehicle; according to the change of the actual slip rate of the middle bridge and the rear axle, the distribution ratio of the energy recovery torque of the middle bridge and the rear axle is dynamically adjusted.

8. The dual electric drive axle vehicle driving control method based on slip ratio according to claim 1, characterized in that: In the step of determining the driving control strategy according to the actual slip ratio of the middle axle and the rear axle, wherein the driving control strategy at least includes the torque distribution ratio between the middle axle and the rear axle, the following further comprises: Determining a relative slip rate according to the actual slip rates of the middle axle and the rear axle; determining whether the absolute value of the relative slip rate exceeds a third preset threshold; When the absolute value of the relative slip ratio exceeds a third preset threshold, differential torque regulation is performed, and for a bridge with a larger slip ratio, a first regulation coefficient is used to reduce its driving torque, and for a bridge with a smaller slip ratio, a second regulation coefficient is used to reduce its driving torque, wherein the first regulation coefficient is greater than the second regulation coefficient; The above steps are iteratively performed until the absolute value of the relative slip ratio does not exceed a third preset threshold.

9. The dual electric drive axle vehicle driving control method based on slip ratio according to claim 1, characterized in that: The step of determining the driving control strategy according to the actual slip ratio of the middle axle and the rear axle, wherein the driving control strategy at least includes the torque distribution ratio between the middle axle and the rear axle, further includes: The actual slip rates of the middle axle and the rear axle are continuously monitored, and when it is detected that the actual slip rate of any axle is abnormal and exceeds a preset time threshold, a fault warning message is generated.

10. The dual electric drive axle vehicle driving control method based on slip ratio according to any one of claims 1 to 9, characterized in that: Also includes: Get the distance and relative speed to the vehicle in front; When the actual slip rate of any bridge is greater than a fourth preset threshold value, and the distance to the leading vehicle is less than a safety distance threshold value, and / or the relative speed to the leading vehicle is greater than a speed difference threshold value, the vehicle acceleration response sensitivity is reduced, the target following distance to the leading vehicle is increased, the deceleration intensity is adjusted according to the relative speed, and the torque distribution ratio between the middle bridge and the rear bridge is adjusted; When the actual slip rates of all bridges are not greater than the fourth preset threshold, and the distance and relative speed to the leading vehicle are within a safe range, the standard acceleration response sensitivity is gradually restored, and the target following distance to the leading vehicle is restored to the default setting.

11. A dual electric drive axle vehicle driving control device based on slip ratio, characterized in that: Applied to 6×4 vehicles, the device comprises: A first acquisition module is used to acquire the speed signals of the front axle, the middle axle and the rear axle; An initial slip ratio calculation module, used to determine the initial slip ratios of the middle axle and the rear axle relative to the front axle respectively according to the speed signals of the axles; A second acquisition module is used to acquire the vehicle load status and / or current road condition information, wherein the road condition information at least includes a road slope; A correction module, configured to correct the initial slip rates of the middle bridge and the rear bridge based on the vehicle load state and / or the current road condition, so as to obtain actual slip rates of the middle bridge and the rear bridge; The control module is used to determine a driving control strategy according to the actual slip rates of the middle axle and the rear axle, wherein the driving control strategy at least includes a torque distribution ratio between the middle axle and the rear axle.

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