Steering control method, device, equipment and medium of distributed drive vehicle

Abstract

The application provides a steering control method, device, equipment and medium of a distributed drive vehicle. In the scheme, the vehicle controller detects whether the original steering function is turned on, judges whether the preset original steering activation condition is met, calculates the road adhesion coefficient after the original steering activation condition is met, determines the original steering direction of the vehicle, then queries the control time table according to the accelerator pedal opening degree and the road adhesion coefficient to obtain the control response time of the rear inner drive motor. Finally, the vehicle is controlled to perform the original steering according to the original steering direction, the target yaw torque and the control response time of the rear inner drive motor. In this way, the stable control of the original steering of the distributed drive vehicle is realized, so that the vehicle can realize the original steering in a stable state.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicles, in particular to a steering control method, device and equipment of a distributed drive vehicle and a medium. BACKGROUND

[0002] With the development of vehicle technology, the driving mode of the vehicle is no longer limited to the centralized driving mode, and more and more vehicles begin to use distributed driving to realize vehicle control. The steering ability of the vehicle is one of the basic properties of the vehicle, and the minimum turning radius of the vehicle is usually taken as an important parameter for evaluating the steering performance of the vehicle. The minimum turning radius refers to the radius of the track circle that the center of the outer steering wheel rolls on the supporting plane when the steering wheel is turned to the limit position and the vehicle is driven at the lowest stable speed. It largely represents the ability of the vehicle to pass through narrow curved areas or to bypass obstacles that cannot be crossed.

[0003] In the prior art, the implementation of the original steering function is mainly concentrated in tracked vehicles or in all-wheel steering vehicles with steering mechanisms installed on each wheel, but tracked vehicles are only used for special purposes and have a narrow range of application, and all-wheel steering vehicles need to be equipped with additional steering systems, which not only increases the cost of the vehicle and the complexity of the mechanical structure, but also puts forward higher requirements for the control of the driving and steering systems, both of which are not suitable for passenger vehicles.

[0004] At present, there is little research on the original steering control scheme of the distributed drive vehicle, and there is a lack of a technical scheme for controlling the original steering of the distributed drive vehicle. SUMMARY

[0005] The present application provides a steering control method, device, equipment and medium of a distributed drive vehicle. A technical scheme for controlling the original steering of the distributed drive vehicle is provided.

[0006] In the first aspect, the present application provides a steering control method of a distributed drive vehicle, comprising:

[0007] After detecting that the original steering function is turned on, it is judged whether the preset original steering activation condition is met according to the state of the vehicle itself;

[0008] If the vehicle meets the original steering activation condition, the road adhesion coefficient is calculated according to the ground adhesion force and the ground normal reaction force, and the road adhesion coefficient is used to control the optimal target slip rate of the wheel;

[0009] The original steering direction of the vehicle is determined according to the steering angle of the steering wheel;

[0010] determining a control response time of a rear inner side driving motor of the vehicle according to an accelerator pedal opening degree of the vehicle, a road adhesion coefficient, and a control schedule, wherein the control schedule comprises control times corresponding to different accelerator pedal opening degrees and road adhesion coefficients determined according to experiments;

[0011] controlling the vehicle to perform the spin according to the spin direction, the target yaw torque, and the control response time of the rear inner side driving motor of the vehicle.

[0012] In an embodiment, the method further comprises:

[0013] obtaining an actual yaw angular velocity of the vehicle;

[0014] determining the target yaw torque of the vehicle according to the actual yaw angular velocity and a target yaw angular velocity.

[0015] In an embodiment, the calculating the road adhesion coefficient according to the ground adhesion force and the ground normal reaction force comprises:

[0016] using a formula: to calculate the road adhesion coefficient; wherein, represents the adhesion coefficient; represents the adhesion force; F z represents the ground normal reaction force; Fxmax represents the limit value of the ground tangential reaction force.

[0017] In an embodiment, the determining whether the vehicle meets the preset spin activation condition according to the state of the vehicle itself comprises:

[0018] obtaining a disassociated fault flag bit, a safety condition flag bit, and a state of a brake pedal of the vehicle;

[0019] if the disassociated fault flag bit is 1, the safety condition flag bit is also set to 1, and the brake pedal is in a released state, it is determined that the vehicle meets the preset spin activation condition.

[0020] In an embodiment, the controlling the vehicle to perform the spin according to the spin direction, the target yaw torque, and the control response time of the rear inner side driving motor of the vehicle comprises:

[0021] controlling the vehicle to perform the spin according to the control response time of the rear inner side driving motor of the vehicle and the spin direction;

[0022] In the process of steering, determining a request torque of an outer side driving motor of the vehicle according to the target yaw torque, a motor capability limit value of the driving motor, and a battery power limit value.

[0023] sending the outside drive motor request torque to an outside drive motor of the vehicle.

[0024] In one embodiment, the method further comprises:

[0025] acquiring a slip ratio of a drive wheel of the vehicle in real time during steering of the vehicle;

[0026] controlling the vehicle to stop steering if the slip ratio of the drive wheel is greater than or equal to a preset vehicle slip ratio safety threshold, wherein the vehicle slip ratio safety threshold is determined according to a maximum slip ratio of the wheel.

[0027] In one embodiment, the method further comprises:

[0028] acquiring a current vehicle speed and a motor speed of a rear inside wheel of the vehicle during steering of the vehicle;

[0029] determining whether the vehicle enters an ASC mode according to the current vehicle speed, the motor speed of the rear inside wheel and a preset speed interval of the ASC mode;

[0030] controlling the motor of the rear inside wheel of the vehicle according to a brake torque generated by the ASC mode after the vehicle enters the ASC mode.

[0031] In a second aspect, an embodiment of the present application provides a steering control device for a distributed drive vehicle, comprising:

[0032] a first processing module configured to determine whether a preset steering-on-the-spot activation condition is met according to a state of the vehicle after detecting that a steering-on-the-spot function is turned on;

[0033] a second processing module configured to calculate a road adhesion coefficient according to a ground adhesion force and a ground normal reaction force if the vehicle meets the steering-on-the-spot activation condition, the road adhesion coefficient being used to control a best target slip ratio of a wheel;

[0034] a third processing module configured to determine a steering-on-the-spot direction of the vehicle according to a steering angle of a steering wheel;

[0035] a querying module configured to determine a control response time of a rear inside drive motor of the vehicle according to an accelerator pedal opening degree of the vehicle, the road adhesion coefficient and a control time table, the control time table including control times corresponding to different accelerator pedal opening degrees and road adhesion coefficients determined according to experiments;

[0036] a control module, configured to control the vehicle to perform the spin based on the spin direction, the target yaw torque, and a control response time of a rear inboard drive motor of the vehicle.

[0037] In an embodiment, the apparatus further comprises a fifth processing module configured to:

[0038] obtain an actual yaw rate of the vehicle;

[0039] determine the target yaw torque of the vehicle based on the actual yaw rate and a target yaw rate.

[0040] In an embodiment, the second processing module is specifically configured to:

[0041] obtain the road adhesion coefficient by using a formula: wherein, represents the adhesion coefficient; represents the adhesion force; F z represents the ground normal reaction force; and Fxmaxrepresents the limit value of the ground tangential reaction force.

[0042] In an embodiment, the first processing module is specifically configured to:

[0043] obtain a disassociated fault flag, a safety condition flag, and a state of a brake pedal of the vehicle;

[0044] if the disassociated fault flag is 1, the safety condition flag is also set to 1, and the brake pedal is in a released state, it is determined that the vehicle satisfies the preset steering activation condition.

[0045] In an embodiment, the control module is specifically configured to:

[0046] control the vehicle to perform the spin based on the control response time of the rear inboard drive motor of the vehicle and the spin direction;

[0047] during the steering, determine a request torque of an outboard drive motor of the vehicle based on the target yaw torque, a motor capability limit value of the drive motor, and a battery power limit value;

[0048] send the request torque of the outboard drive motor to the outboard drive motor of the vehicle.

[0049] In an embodiment, the control module is further configured to:

[0050] during the steering of the vehicle, obtain a slip rate of a drive wheel of the vehicle in real time;

[0051] If the slip ratio of the driving wheel is greater than or equal to a preset vehicle slip ratio safety threshold value, the vehicle is controlled to stop steering, wherein the vehicle slip ratio safety threshold value is determined according to the maximum slip ratio of the wheel.

[0052] In a specific embodiment, the control module is further configured to:

[0053] During steering of the vehicle, the current vehicle speed and the motor speed of the rear inner wheel of the vehicle are obtained;

[0054] According to the current vehicle speed, the motor speed of the rear inner wheel, and the speed interval of the preset ASC mode, it is determined whether the vehicle enters the ASC mode;

[0055] After the vehicle enters the ASC mode, the motor of the rear inner wheel of the vehicle is controlled according to the brake torque generated by the ASC mode.

[0056] In a third aspect, the embodiments of the present application provide a vehicle, comprising: a vehicle body, a vehicle controller, a motor of each wheel, a memory, and computer program instructions stored on the memory and executable on the vehicle controller, wherein the vehicle controller executes the computer program instructions to implement the steering control method of the distributed drive vehicle according to any one of the first aspect.

[0057] In a fourth aspect, the embodiments of the present application provide a computer readable storage medium, wherein the computer readable storage medium stores computer execution instructions, and the computer execution instructions are used to implement the steering control method of the distributed drive vehicle according to any one of the first aspect.

[0058] The embodiments of the present application provide a steering control method, device, equipment and medium of a distributed drive vehicle. In the scheme, the vehicle controller detects that the original steering function is turned on, judges whether the preset original steering activation condition is met, calculates the road adhesion coefficient after the original steering activation condition is met, determines the original steering direction of the vehicle, then queries the control time table according to the accelerator pedal opening degree and the road adhesion coefficient to obtain the control response time of the rear inner drive motor. Finally, the vehicle is controlled to perform original steering according to the original steering direction, the target yaw torque and the control response time of the rear inner drive motor. In this way, the stable control of the original steering of the distributed drive vehicle is realized, and the vehicle realizes the original steering in a stable state. BRIEF DESCRIPTION OF DRAWINGS

[0059] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0060] Figure 1aA schematic diagram of a distributed driving mode provided for an embodiment of the present application;

[0061] Figure 1b A schematic diagram of another distributed driving mode provided for an embodiment of the present application;

[0062] Figure 2 A principle diagram of a spot turning of a distributed driving vehicle provided for an embodiment of the present application;

[0063] Figure 3 A flowchart of a steering control method embodiment of a distributed driving vehicle provided for an embodiment of the present application;

[0064] Figure 4 An entering and exiting condition judgment schematic diagram of a spot turning mode provided for an embodiment of the present application;

[0065] Figure 5 A spot turning direction judgment mode schematic diagram provided for an embodiment of the present application;

[0066] Figure 6 A principle schematic diagram of a steering control method of a distributed driving vehicle provided for an embodiment of the present application;

[0067] Figure 7 An ASC mode interval schematic diagram provided for an embodiment of the present application;

[0068] Figure 8 A motor ASC characteristic curve schematic diagram provided for an embodiment of the present application;

[0069] Figure 9 An IGBT working state schematic diagram of a motor ASC mode provided for an embodiment of the present application;

[0070] Figure 10 A structure schematic diagram of a steering control device of a distributed driving vehicle provided for an embodiment of the present application.

[0071] Through the above-mentioned drawings, the explicit embodiments of the present application have been shown, and there will be more detailed descriptions hereinafter. These drawings and textual descriptions are not intended to limit the scope of the concept of the present application by any means, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0072] To make the purposes, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort should fall within the protection scope of the present application.

[0073] Before introducing the embodiments of the present application, the application background of the embodiments of the present application is first explained:

[0074] The steering capability of a vehicle is one of the basic properties of the vehicle, and the minimum turning radius of the vehicle is usually taken as an important parameter for evaluating the steering performance of the vehicle. The minimum turning radius refers to the radius of the track circle through which the center of the outer steering wheel rolls on the supporting plane when the steering wheel is turned to the limit position and the vehicle is driven at the lowest stable speed. It largely represents the capability of the vehicle to pass through a narrow curved zone or to bypass an insurmountable obstacle. The current in-place steering is only focused on tracked vehicles or all-wheel steering vehicles, and none of these schemes is applicable to passenger cars.

[0075] Figure 1a A schematic diagram of a distributed driving mode provided by the embodiments of the present application is shown in FIG. 1, Figure 1b A schematic diagram of another distributed driving mode provided by the embodiments of the present application is shown in FIG. 2. Figure 1a and 1b As shown in FIGS. 1 and 2, the distributed driving refers to a new power form in which a single wheel is directly driven by an electric motor. The hub motor, the wheel-side motor, and the central distributed motor all belong to the power form of the distributed driving. The distributed driving has the advantages of compact structure, short transmission chain, fast power response speed, high control precision, and high efficiency of the driving system. Through the accurate control of the power output of the motor of each wheel, the functions of the electronic differential of the vehicle, the electric brake, and the vector control can be cleverly realized.

[0076] Figure 1a In the centralized determination mode in FIG. 3, two motors drive the front wheels and the rear wheels respectively, two front wheels are driven by one motor driving system, and two rear wheels are driven by one motor driving system, that is, the electric driving system. In the distributed driving, two rear wheels are driven by separate electric driving systems. Figure 1b The two distributed driving modes in FIG. 4 include three-motor driving and four-motor driving. For the case of three motors, as shown in the figure, two rear wheels are driven by separate electric driving systems, and two front wheels are driven by the same motor driving system. For the case of four motors, each wheel can be provided with a separate electric driving system for driving.

[0077] Currently, there is little research on the in-place turning control scheme of a distributed drive vehicle. For a traditional central centralized drive vehicle, in-place turning control is mostly achieved by relying on a hydraulic brake system to lock the rear inner wheel to drag and slide, and then to realize in-place turning control. The hydraulic brake system highly depends on the reliability and brake efficiency of the hydraulic brake system, and needs to go through a large number of calibration tests. The response is slow, the use scene is limited, and the function can only be used by manual intervention through road identification. For a vehicle with a part-hub motor structure, a four-wheel steering mechanism needs to be added to take the vehicle center of mass as the turning center of the four wheels to realize in-place turning. This scheme requires the vehicle to add a rear axle steering mechanism, which is complex in structure and high in cost.

[0078] To solve the above problems, the application provides a steering control method for a distributed drive vehicle. In this scheme, the traditional in-place turning scheme relying on a chassis controller, ABS and hydraulic calipers is abandoned. The implementation principle is to control the hydraulic brake system to lock the rear inner wheel, and adjust the turning radius and vehicle stability of the vehicle according to the steering wheel angle, vehicle attitude and road adhesion coefficient. This scheme is applicable to all vehicles with a rear axle distributed drive motor.

[0079] Figure 2 The in-place turning principle diagram of the distributed drive vehicle provided by the embodiment of the application is shown in FIG. 1. As shown in the figure, during in-place turning, the vehicle takes the rear inner wheel as the center to realize the minimum turning radius. Compared with the traditional vehicle turning method, the turning radius of the vehicle is greatly reduced. R in the figure represents the turning radius required by the traditional vehicle turning, and r represents the turning radius of the in-place turning provided in this scheme. Figure 2

[0080] Figure 3 The flowchart of the steering control method for the distributed drive vehicle provided by the embodiment of the application is shown in FIG. 2. The steering control method for the distributed drive vehicle is applied to the vehicle controller of the vehicle. The method comprises the following steps. Figure 3

[0081] S101: After detecting that the in-place turning function is turned on, it is judged whether the preset in-place turning activation condition is met according to the state of the vehicle itself.

[0082] In this scheme, when the vehicle driven by the user needs to turn in place, the user needs to manually operate to turn on the in-place turning function of the vehicle. When the vehicle detects that the in-place turning function is turned on by the user, the safety condition, fault condition and other related states of the vehicle itself need to be acquired to determine whether the state of the current vehicle meets the in-place turning activation condition. Only when the in-place turning activation condition of the vehicle is met, in-place turning is performed.

[0083] In one specific implementation, Figure 4 ​​This is a schematic diagram illustrating the entry and exit conditions for the stationary turning mode provided in an embodiment of this application, as shown below. Figure 4 As shown, after turning on the U-turn switch (i.e., the stationary steering function switch), i.e., setting it from 0 to 1, it is necessary to determine whether the safety conditions are met. If the no-fault flag is 1, the safety condition flag is 1, and the U-turn switch is also 1, then the vehicle's status is determined to meet the stationary steering activation conditions. After the driver releases the brake pedal, the vehicle's stationary steering function is confirmed to be activated, and stationary steering control proceeds according to the subsequent process. If the safety conditions are not met, or the driver actively depresses the brake pedal, or the driver does not release the brake pedal, or the driver turns off the U-turn switch, or a related fault exists, then the stationary steering activation conditions are not met, and it is necessary to wait for it to close by setting the U-turn switch to 0.

[0084] In another specific implementation, when determining whether the steering activation condition is met, the vehicle's unrelated fault flag, safety condition flag, and brake pedal status are obtained. If the unrelated fault flag is set to 1, the safety condition flag is also set to 1, and the brake pedal is released, then the vehicle is determined to meet the preset steering activation condition. If any one of the three conditions is not met, the vehicle does not meet the steering activation condition.

[0085] S102: If the vehicle meets the conditions for activating stationary steering, the road surface adhesion coefficient is calculated based on the ground adhesion force and the ground normal reaction force.

[0086] In this step, after determining that the vehicle meets the conditions for activating stationary steering, the vehicle controller needs to calculate the road adhesion coefficient. The road adhesion coefficient is used to control the optimal target slip ratio of the wheels. It should be understood that the road adhesion coefficient refers to the ratio of the adhesion force to the wheel's normal (perpendicular to the road surface) pressure. In a rough calculation, it can be considered as the static friction coefficient between the tire and the road surface. It is determined by the road surface and the tire; the larger this coefficient, the greater the available adhesion force and the less likely the vehicle is to slip. In this scheme, the purpose of calculating the road adhesion coefficient is to control the maximum slip ratio of individual wheels. The inner rear wheel is at the center of the vehicle's turning radius, allowing for lock-up and slippage, i.e., allowing for a larger slip ratio. The outer rear wheel and the front axle wheels are steering drive wheels, needing to provide turning driving force and minimizing slippage to generate ground driving force.

[0087] In one specific implementation of this scheme, the formula can be used: The adhesion coefficient of the road surface was calculated; where, Indicates the adhesion coefficient; Indicates adhesion; F zFy represents the normal reaction force of the ground; Fxmax represents the limit value of the tangential reaction force of the ground.

[0088] The adhesion rate refers to the minimum adhesion coefficient required when the driving force is fully exerted in the straight driving condition of the vehicle, and thus is:

[0089] The adhesion rates of the four wheels can be obtained respectively by the driving force and the vertical load of the four wheels: tire adhesion rate = wheel driving force / wheel load.

[0090] In the process of vehicle control, when the absolute value of the slip rate of the tire is less than a certain value, it can be determined that the ground can provide sufficient adhesion, at which time the adhesion coefficient of the tire takes the maximum adhesion rate in the process, otherwise, the adhesion coefficient of the tire takes the minimum adhesion rate in the process. Otherwise, the adhesion coefficient of the tire takes the minimum adhesion rate in the process, and finally filters the output.

[0091] S103: Determine the turning direction of the vehicle according to the steering angle of the steering wheel.

[0092] In this step, when the driver needs to perform the turning, the steering wheel can be operated to turn the steering wheel in the direction of the U-turn required. The vehicle controller can obtain the steering angle of the steering wheel, and then determine the turning direction required by the driver based on the degree or size of the steering angle.

[0093] In a specific implementation scheme, Figure 5 A schematic diagram of a turning direction judgment method provided by an embodiment of the application is shown in FIG. 2, in which Figure 5 As shown in FIG. 2, a threshold value of the steering angle can be set, when the steering angle of the steering wheel is greater than the absolute value of the threshold value, it is determined to be left turning, that is, the turning direction of the U-turn is left turning. When the steering angle of the steering wheel is less than the absolute value of the negative threshold value, it is determined to be right turning, that is, the turning direction of the U-turn is right turning.

[0094] S104: Determine the control response time of the rear inner side driving motor of the vehicle according to the accelerator pedal opening degree of the vehicle, the road adhesion coefficient and the control time table.

[0095] The control time table includes the control time corresponding to different accelerator pedal opening degrees and road adhesion coefficients determined according to experiments.

[0096] In this step, the vehicle controller also needs to determine the control response time of the rear inner side driving motor, so as to control the lock and slip time of the rear inner side wheel according to the control response time.

[0097] In one implementation, the vehicle controller can determine the control response time of the rear inner drive motor according to the accelerator pedal opening and the aforementioned road adhesion coefficient, and query a control schedule (an example of a control schedule is shown in Table 1) obtained in advance according to experiments, to control the vehicle, for example: in the case of large accelerator pedal opening and low ground adhesion coefficient, it is considered that the driver needs to turn with the smallest radius, and the current tire friction resistance is small, the inner motor can be controlled to be long time locked and dragged.

[0098] Table 1 Control schedule

[0099] 0 10 20 30 40 50 60 70 80 90 100 1.00 0 2.4576 4.9152 7.3728 9.8304 12.288 14.7456 17.2032 19.6608 22.1148 24.576 0.80 0 3.072 6.144 9.216 12.288 15.36 18.432 21.504 24.576 27.648 30.72 0.60 0 3.84 7.68 11.52 15.36 19.2 23.04 26.88 30.72 34.56 38.4 0.40 0 4.8 9.6 14.4 19.2 24 28.8 33.6 38.4 43.2 48 0.20 0 6 12 18 24 30 36 42 48 54 60

[0100] In Table 1, the horizontal 1-100 represents the accelerator pedal opening, and the vertical 0.20-1.00 represents the road adhesion coefficient. The vehicle controller can query Table 1 according to the calculated road adhesion coefficient and the obtained accelerator pedal opening of the vehicle to obtain the final control response time of the rear inner drive motor.

[0101] S105: controlling the vehicle to perform the spin according to the spin direction, the target yaw torque and the control response time of the rear inner drive motor of the vehicle.

[0102] In this step, the vehicle controller controls the vehicle to spin based on the spin direction, the target yaw torque and the response time of the rear inner drive motor after obtaining them. In this process, it should be understood that the vehicle controller needs to obtain the actual yaw angular velocity of the vehicle, and then determine the target yaw torque of the vehicle according to the actual yaw angular velocity and the obtained target yaw angular velocity.

[0103] In a specific control process, the vehicle controller controls the vehicle to spin according to the spin direction of the vehicle based on the control response time of the rear inner drive motor of the vehicle. And in the process of spinning, the outer drive motor request torque of the vehicle is determined according to the target yaw torque, the motor capacity limit of the drive motor and the battery power limit, and the outer drive motor request torque is sent to the outer drive motor of the vehicle. That is, in the whole process of spinning, the rear inner motor controls the rear inner wheel to be locked, and the outer motor drives during spinning.

[0104] At the same time, the slip rate of the drive wheel of the vehicle needs to be obtained in real time during the spinning process of the vehicle. If the slip rate of the drive wheel is greater than or equal to a preset vehicle slip rate safety threshold, the vehicle is controlled to stop spinning, to avoid the vehicle slipping on a low adhesion road or causing the vehicle to lose stability, and to ensure the stability and safety of the spinning process. The vehicle slip rate safety threshold is determined according to the maximum slip rate of the wheel.

[0105] And, during the steering of the vehicle, the current vehicle speed and the motor speed of the rear inner wheel of the vehicle are acquired, and whether the vehicle enters an ASC mode is determined according to the current vehicle speed, the motor speed of the rear inner wheel and a preset motor active short circuit (ASC) mode speed range, and after the vehicle enters the ASC mode, the motor of the rear inner wheel of the vehicle is controlled according to a brake torque generated by the ASC mode.

[0106] The steering control method of the distributed drive vehicle provided by the embodiment is used for steering operation according to the above process, the whole steering process is light, the vehicle realizes steering in place with the rear inner wheel as the center, the minimum turning radius is realized, the turning radius of the vehicle is greatly reduced compared with the traditional steering mode, and the passability of the vehicle in special environments is ensured. Moreover, the hydraulic brake system of the chassis controller does not need to participate in the steering process, the complexity of the control system is reduced, and no additional hardware and software costs are needed; the steering process controls the inner wheel driving motor in zero torque control and ASC mode control, the hydraulic brake system does not consume the power of the whole vehicle, and the economy is good; the locking strength of the inner wheel is determined according to the road adhesion coefficient, the stability and safety of the vehicle are ensured, the tires are protected, and excessive wear is avoided.

[0107] Based on the description of the above embodiment, the scheme is exemplified by a specific implementation.

[0108] Figure 6 The principle diagram of the steering control method of the distributed drive vehicle provided by the embodiment is shown in Figure 6 After the driver turns on the steering in place function, the vehicle controller judges the steering activation condition, if the steering activation condition is not met, the vehicle continues to normally drive and does not perform steering in place control. If the steering activation condition is met, it is necessary to continue to determine whether there is a motor system fault, if there is no motor system fault, steering in place operation is performed, and in this process, it is necessary to judge the relationship between the motor speed and the target speed in real time, when the motor speed is greater than the target speed, ASC mode control is performed, and motor over-temperature detection is performed during ASC mode control, if motor over-temperature occurs, 0 torque control can be performed. During the process that the motor speed is less than or equal to the target speed, 0 torque control is directly performed. If it is determined that there is a motor system fault, torque limiting or speed limiting driving needs to be performed. Regardless of the driving mode, detection of the same coaxial motor response same protection measures is needed.

[0109] Specifically, the scheme can include the following implementation steps:

[0110] 1. First, the steering activation condition is judged after the steering in place function is detected to be turned on.

[0111] 2, after the steering activation condition is met, the road adhesion coefficient is calculated according to the formula in the foregoing manner.

[0112] 3, the direction of the original steering is determined according to the steering wheel angle.

[0113] 4, the control response time of the rear-inboard motor is determined according to the accelerator pedal opening and the road adhesion coefficient, and specifically, the table lookup manner provided in the foregoing embodiment can be used.

[0114] 5, the vehicle slip ratio safety threshold value is set in the vehicle in advance according to the maximum slip ratio, and in the original steering process, it is monitored whether the drive wheel slip ratio exceeds the safety threshold value, so as to avoid the vehicle instability caused by the drive wheel slip of the vehicle on the low adhesion road.

[0115] 6, the vehicle target yaw moment is determined according to the actual yaw rate and the target yaw rate, the driving force and the yaw moment are distributed to the drive wheels according to the torque distribution principle, so as to ensure the target driving force and the vehicle stability driving.

[0116] 7, in the whole steering process, the request torque of the outboard drive motor is determined according to the target yaw moment, the motor capacity limit value and the battery power limit value, and the whole control process needs to monitor the capacity and state of each drive motor, the capacity and state of the battery, so as to avoid the faults such as the over-discharge of the battery and the overheat of the high-voltage system caused by the excessive demand power.

[0117] 8, whether to enter the ASC mode is determined according to the current vehicle speed and the rear-inboard motor speed. Figure 7 An ASC mode interval diagram provided for the embodiment of the application is shown in FIG. 1. Figure 7 As shown in FIG. 1, the speed interval of the ASC effect can be set in advance according to the motor ASC characteristics, and when the vehicle controller controls the motor to reach the upper limit of the target speed, the ASC mode is entered to generate the required braking torque in the steering process.

[0118] Figure 8 An ASC characteristic curve diagram of the motor provided for the embodiment of the application is shown in FIG. 2. Figure 9 An IGBT working state diagram of the motor ASC mode provided for the embodiment of the application is shown in FIG. 3. Figure 8 and Figure 9The motor ASC characteristic is an inherent property of the motor and can be obtained through motor bench testing. Taking a three-phase IGBT power module as an example, the active short-circuit protection safe working state is achieved by turning off the three upper bridge arms of the IGBT and turning on the three lower bridge arms of the IGBT, or turning on the three upper bridge arms of the IGBT and turning off the three lower bridge arms of the IGBT. When the motor enters the active short-circuit working mode, the motor stator winding and the IGBT of the lower bridge arm form a closed loop circuit, and the back electromotive force energy generated by the motor is released through the stator winding. The torque-speed characteristic of the motor after entering the ASC mode is shown in FIG. 8. Figure 8 As shown in FIG. 8, it can be seen that the motor output end can generate a corresponding braking torque in the ASC mode, thereby realizing the locking and sliding of the inner wheels.

[0119] 9. During the steering process, the vehicle stability control is entered according to the actual yaw angular velocity and yaw angular acceleration of the vehicle, and a target yaw moment is generated to control the body stability.

[0120] 10. During the steering process, the cooling system capability level is controlled according to the over-temperature condition and fault state of the rear inner motor, and the ASC mode of the motor is controlled to enter and exit.

[0121] During the entire on-the-spot steering process, the core of the technical solution is the estimation of the road adhesion coefficient, the vehicle stability control, the ASC control process of the inner motor, and the torque distribution process of the outer motor. The specific distribution method can be distributed according to the distributed torque distribution principle.

[0122] The steering control method of the distributed drive vehicle provided in the present application estimates the maximum yaw angular velocity limit of the current road condition according to the road adhesion coefficient during the entire steering control process, determines the minimum turning radius that can be achieved according to the turning direction and the current steering angle determined by the steering wheel angle of the vehicle, and judges the maximum steering safety speed of the vehicle according to the accelerator pedal opening degree of the driver. In the specific control process, the ASC mode characteristics of the motor are used to realize the locking and sliding of the inner wheels of the vehicle by the motor during the steering process, and the outer wheels drive the vehicle to steer without the participation of the chassis controller and the hydraulic brake system. The entire steering process is completed independently by the electric drive system, thereby realizing a smaller steering radius during the entire steering process and a simple control process, and the steering process is stable and safe.

[0123] The following is an apparatus embodiment of the present application, which can be used to execute the method embodiments of the present application. For details not disclosed in the apparatus embodiments of the present application, please refer to the method embodiments of the present application.

[0124] Figure 10 The structure diagram of the steering control device of the distributed drive vehicle provided in the present application embodiment is shown in FIG. 10. Figure 10 As shown in FIG. 10, the steering control device 10 of the distributed drive vehicle includes:

[0125] The first processing module 11 is configured to determine whether a preset spin-on-the-spot activation condition is met according to a state of the vehicle after detecting that the spin-on-the-spot function is turned on.

[0126] The second processing module 12 is configured to calculate a road adhesion coefficient according to a ground adhesion force and a ground normal reaction force if the spin-on-the-spot activation condition is met by the vehicle, and the road adhesion coefficient is used to control a wheel optimal target slip ratio.

[0127] The third processing module 13 is configured to determine a spin-on-the-spot direction of the vehicle according to a steering wheel rotation angle.

[0128] The query module 14 is configured to determine a control response time of a rear inner side drive motor of the vehicle according to an accelerator pedal opening degree of the vehicle, the road adhesion coefficient, and a control time table, wherein the control time table includes control times corresponding to different accelerator pedal opening degrees and road adhesion coefficients determined according to experiments.

[0129] The control module 15 is configured to control the vehicle to perform spin-on-the-spot according to the spin-on-the-spot direction, a target yaw torque, and the control response time of the rear inner side drive motor of the vehicle.

[0130] Optionally, the device 10 further includes a fifth processing module 16, which is configured to:

[0131] acquire an actual yaw angular velocity of the vehicle;

[0132] determine the target yaw torque of the vehicle according to the actual yaw angular velocity and a target yaw angular velocity.

[0133] Optionally, the second processing module 12 is specifically configured to:

[0134] use a formula: to calculate the road adhesion coefficient, wherein represents an adhesion coefficient; represents an adhesion force; F z represents a ground normal reaction force; and Fxmax represents a limit value of a ground tangential reaction force.

[0135] Optionally, the first processing module 11 is specifically configured to:

[0136] acquire a non-associated fault flag bit, a safety condition flag bit, and a state of a brake pedal of the vehicle;

[0137] if the non-associated fault flag bit is 1, the safety condition flag bit is also set to 1, and the brake pedal is in a released state, it is determined that the vehicle meets the preset spin-on-the-spot activation condition.

[0138] Optionally, the control module 15 is specifically configured to:

[0139] controlling the vehicle to perform the spin based on a control response time of a rear inner drive motor of the vehicle and the spin direction;

[0140] during the steering, determining a request torque of an outer drive motor of the vehicle based on the target yaw moment, a motor capability limit of the drive motor and a battery power limit;

[0141] sending the request torque of the outer drive motor to the outer drive motor of the vehicle.

[0142] Optionally, the control module 15 is further configured to:

[0143] during the steering of the vehicle, acquiring a slip rate of a drive wheel of the vehicle in real time;

[0144] if the slip rate of the drive wheel is greater than or equal to a preset vehicle slip rate safety threshold, controlling the vehicle to stop steering, wherein the vehicle slip rate safety threshold is determined according to a maximum slip rate of the wheel.

[0145] Optionally, the control module 15 is further configured to:

[0146] during the steering of the vehicle, acquiring a current vehicle speed and a motor speed of a rear inner wheel of the vehicle;

[0147] determining whether the vehicle enters an ASC mode based on the current vehicle speed, the motor speed of the rear inner wheel and a speed interval of a preset ASC mode;

[0148] after the vehicle enters the ASC mode, controlling a motor of the rear inner wheel of the vehicle based on a brake torque generated by the ASC mode.

[0149] The steering control device of the distributed drive vehicle according to any one of the preceding embodiments, which is configured to implement the technical solutions in any one of the preceding method embodiments, has similar implementation principles and technical effects, which will not be described here again.

[0150] It should be noted that the division of each module of the above apparatus is only a logical function division, and all or part of them can be integrated into a physical entity or physically separated when actually implemented. And these modules can all be implemented in the form of software called by a processing element; or all in the form of hardware; or part of the modules are implemented in the form of software called by a processing element, and part of the modules are implemented in the form of hardware. In addition, all or part of these modules can be integrated together, or can be independently implemented. The processing element described herein can be an integrated circuit with signal processing capability. In the implementation process, each step of the above method or each module can be completed by the integrated logic circuit of hardware in the processor element or the instruction in the form of software.

[0151] In addition, the present application also provides a vehicle, which comprises a vehicle body, a vehicle controller, a motor of each wheel, a memory, and computer program instructions stored on the memory and executable on the vehicle controller, and the vehicle controller is configured to implement the technical solutions of the steering control method of the distributed drive vehicle in any one of the method embodiments when executing the computer program instructions.

[0152] Optionally, the above-mentioned various devices in the vehicle can be connected through a system bus.

[0153] The memory can be a separate storage unit, or an integrated storage unit in the vehicle controller.

[0154] Optionally, the vehicle can further comprise an interface for interacting with other devices, a display for displaying information to a user, and the like.

[0155] It should be understood that the vehicle controller can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), etc. The general-purpose processor can be a microprocessor or any conventional processor, etc. The steps of the method disclosed in the present application can be directly embodied as hardware processor execution, or executed by a combination of hardware and software modules in the processor.

[0156] The system bus can be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus or the like. The system bus can be divided into an address bus, a data bus, a control bus, and the like. For ease of representation, only one thick line is shown in the figure, but it does not mean that there is only one bus or only one type of bus. The memory can include a random access memory (RAM) and can also include a non-volatile memory (NVM), such as at least one disk memory.

[0157] All or part of the steps of the above-mentioned method embodiments can be completed by program instruction related hardware. The aforementioned program can be stored in a readable memory. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned memory (storage medium) includes a read-only memory (ROM), a RAM, a flash memory, a hard disk, a solid state disk, a magnetic tape, a floppy disk, an optical disc, and any combination thereof.

[0158] The vehicle provided by the embodiments of the present application is used to execute the technical solutions provided by any of the method embodiments, and has similar implementation principles and technical effects, which will not be described here.

[0159] The embodiments of the present application provide a computer readable storage medium, which stores computer execution instructions, when the computer execution instructions run on the controller of the vehicle, the vehicle executes the technical solutions of the steering control method of the distributed drive vehicle.

[0160] The computer readable storage medium described above, the readable storage medium can be implemented by any type of volatile or non-volatile storage device or their combination, such as static random access memory, electrically erasable programmable read-only memory, erasable programmable read-only memory, programmable read-only memory, read-only memory, magnetic memory, flash memory, magnetic disk or optical disk. The readable storage medium can be any available medium that can be accessed by a general or special purpose computer.

[0161] Optionally, the read only memory (ROM) can also be used in the processing unit, especially when the device is adapted to operate as a portable media player. Preferably, the processing unit is adapted to write information to the ROM, more preferably information that constitutes at least part of the operational logic of the device. The ROM therefore can be used for storing both instructions and data which the processing unit executes and / or references, preferably during the execution of the instructions.

[0162] It is to be understood that the application is not limited to the precise construction that has been described above and shown in the accompanying drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the application. The scope of the application should only be limited by the claims appended hereto.

Claims

1. A steering control method of a distributed drive vehicle, characterized by, The method comprises the following steps: After detecting that the function of the original turning is turned on, it is judged whether the preset original turning activation condition is met according to the state of the vehicle itself; If the vehicle meets the original turning activation condition, the road adhesion coefficient is calculated according to the ground adhesion force and the ground normal reaction force, and the road adhesion coefficient is used to control the optimal target slip ratio of the wheel; The original turning direction of the vehicle is determined according to the steering angle of the steering wheel; The control response time of the rear inner side drive motor of the vehicle is determined according to the opening degree of the accelerator pedal of the vehicle, the road adhesion coefficient and the control time table, and the control time table includes the control time corresponding to different accelerator pedal opening degrees and road adhesion coefficients determined according to experiments; The vehicle is controlled to perform original turning according to the original turning direction, the target yaw torque and the control response time of the rear inner side drive motor of the vehicle.

2. The method of claim 1, wherein, The method further comprises: The actual yaw angular velocity of the vehicle is obtained; The target yaw torque of the vehicle is determined according to the actual yaw angular velocity and the target yaw angular velocity.

3. The method of claim 1, wherein, The road adhesion coefficient is calculated according to the ground adhesion force and the ground normal reaction force, which comprises: The road surface adhesion coefficient is calculated by the formula: , wherein represents the adhesion coefficient; represents the adhesion force; represents the ground normal reaction force; represents the limit value of the ground tangential reaction force.

4. The method of claim 1, wherein, The vehicle itself state is judged whether the preset original turning activation condition is met, which comprises: The vehicle unrelated fault flag bit, safety condition flag bit and state of the brake pedal are obtained; If the unrelated fault flag bit is 1, the safety condition flag bit is also set to 1, and the brake pedal is in the released state, it is determined that the vehicle meets the preset original turning activation condition.

5. The method according to any one of claims 1 to 4, characterized in that, The vehicle is controlled to perform original turning according to the original turning direction, the target yaw torque and the control response time of the rear inner side drive motor of the vehicle, which comprises: The vehicle is controlled to perform original turning according to the control response time of the rear inner side drive motor of the vehicle and the original turning direction; During the turning process, the outer side drive motor request torque of the vehicle is determined according to the target yaw torque, the motor capacity limit value of the drive motor and the battery power limit value; The outer side drive motor request torque is sent to the outer side drive motor of the vehicle.

6. The method according to any one of claims 1 to 4, characterized in that, The method further comprises: During the turning process of the vehicle, the slip ratio of the drive wheel of the vehicle is obtained in real time; If the slip ratio of the drive wheel is greater than or equal to the preset vehicle slip ratio safety threshold value, the vehicle is controlled to stop turning, wherein the vehicle slip ratio safety threshold value is determined according to the maximum slip ratio of the wheel.

7. The method according to any one of claims 1 to 4, characterized in that, The method further comprises: During the turning process of the vehicle, the current speed of the vehicle and the motor speed of the rear inner side wheel are obtained; Whether the vehicle enters the ASC mode is determined according to the current speed, the motor speed of the rear inner side wheel and the speed interval of the preset motor active short circuit ASC mode; After the vehicle enters the ASC mode, the motor of the rear inner side wheel of the vehicle is controlled according to the brake torque generated by the ASC mode.

8. A steering control device for a distributed drive vehicle, characterized by comprising: The method comprises the following steps: The first processing module is used to judge whether the preset original turning activation condition is met according to the state of the vehicle itself after detecting that the function of the original turning is turned on; The second processing module is configured to calculate a road adhesion coefficient according to a ground adhesion force and a ground normal reaction force if the vehicle meets the original steering activation condition, and the road adhesion coefficient is used to control a wheel optimal target slip ratio. The third processing module is configured to determine an original steering direction of the vehicle according to a steering wheel turning angle. The query module is configured to determine a control response time of a rear inner side drive motor of the vehicle according to an accelerator pedal opening degree of the vehicle, the road adhesion coefficient and a control time table, wherein the control time table includes control times corresponding to different accelerator pedal opening degrees and road adhesion coefficients determined according to experiments. The control module is configured to control the vehicle to perform original steering according to the original steering direction, the target yaw torque and the control response time of the rear inner side drive motor of the vehicle.

9. The apparatus of claim 8, wherein, The device further includes a fifth processing module configured to: obtain an actual yaw angular velocity of the vehicle; and determine the target yaw torque of the vehicle according to the actual yaw angular velocity and a target yaw angular velocity.

10. The apparatus of claim 8, wherein, The second processing module is specifically configured to: The road surface adhesion coefficient is calculated by the formula: , wherein represents the adhesion coefficient; represents the adhesion force; represents the ground normal reaction force; represents the limit value of the ground tangential reaction force.

11. The apparatus of claim 8, wherein, The first processing module is specifically configured to: obtain an unrelated fault flag bit, a safety condition flag bit and a state of a brake pedal of the vehicle; and if the unrelated fault flag bit is 1, the safety condition flag bit is also set to 1 and the brake pedal is in a released state, it is determined that the vehicle meets the preset original steering activation condition.

12. The apparatus of any one of claims 8 to 11, wherein, The control module is specifically configured to: control the vehicle to perform original steering according to the control response time of the rear inner side drive motor of the vehicle and the original steering direction; and determine a request torque of an outer side drive motor of the vehicle according to the target yaw torque, a motor capacity limit value of the drive motor and a battery power limit value during steering; and send the request torque of the outer side drive motor to the outer side drive motor of the vehicle.

13. The apparatus of any one of claims 8 to 11, wherein, The control module is further configured to: obtain a slip ratio of a drive wheel of the vehicle in real time during steering of the vehicle; and if the slip ratio of the drive wheel is greater than or equal to a preset vehicle slip ratio safety threshold value, control the vehicle to stop steering, wherein the vehicle slip ratio safety threshold value is determined according to a maximum slip ratio of the wheel.

14. The apparatus of any one of claims 8 to 11, wherein, The control module is further configured to: obtain a current vehicle speed and a motor rotating speed of a rear inner side wheel of the vehicle during steering of the vehicle; and determine whether the vehicle enters an ASC mode according to the current vehicle speed, the motor rotating speed of the rear inner side wheel and a rotating speed interval of the ASC mode; and control a motor of the rear inner side wheel of the vehicle according to a braking torque generated by the ASC mode after the vehicle enters the ASC mode.

15. A vehicle characterized by comprising: The vehicle includes: a vehicle body, a vehicle controller, a motor of each wheel, a memory and computer program instructions stored on the memory and executable on the vehicle controller, and the vehicle controller is configured to implement the steering control method of the distributed drive vehicle according to any one of claims 1 to 7 when executing the computer program instructions.

16. A computer-readable storage medium, characterized in that, The computer readable storage medium stores computer execution instructions for implementing the steering control method of the distributed drive vehicle according to any one of claims 1 to 7.

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