Braking force distribution method and device, equipment and storage medium

Abstract

The invention discloses a braking force distribution method and device, equipment and a storage medium, and the method comprises the steps: obtaining an observation input parameter and an actual yaw velocity, and carrying out the preprocessing of the observation input parameter, and obtaining a preprocessing parameter; and calculating an ideal yaw velocity according to the preprocessing parameters. Then, feedback control is constructed according to the observation input parameters, the actual yaw velocity and the ideal yaw velocity, and feed-forward control is constructed according to the observation input parameters; when the vehicle speed is not larger than the first preset vehicle speed, the expected yaw moment is calculated through feedforward control; when the vehicle speed is not less than a second preset vehicle speed, calculating an expected yaw moment by using feedback control; when the vehicle speed is larger than the first preset vehicle speed and smaller than the second preset vehicle speed, the expected yaw moment is calculated through compound control, and the second preset vehicle speed is larger than the first preset vehicle speed. And finally, according to the expected yawing moment, braking force distribution is performed to obtain expected braking force. The steering and braking cooperation capability of the drive-by-wire chassis can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of braking force distribution, and in particular to a braking force distribution method, device, equipment and storage medium. Background Art

[0002] With the development of electric and intelligent vehicles, the driving performance and safety of the whole vehicle are becoming more and more important. Based on the software development trend of integrated and modularized chassis, the increasingly mature brake-by-wire and steering-by-wire technologies have made the demand for driving safety more urgent.

[0003] After the vehicle is equipped with a steer-by-wire system, the mechanical hardware's limitation on steering capability limits the vehicle's steering capability when responding to emergency steering and other scenarios. The brake-by-wire system uses independent electrical signals received on the four wheels of the vehicle for independent braking control of the four wheels, which is conducive to coordinated steering / braking control with the chassis domain controller. The lateral and longitudinal coordinated control function is easier to implement in a steer-by-wire chassis system.

[0004] The prior art discloses a variety of methods for using electronically controlled braking to assist steering when the steering assist is insufficient, and controls the vehicle steering by applying direct yaw torque to increase the vehicle steering redundancy. However, in such methods, after the wire-controlled steering system fails and loses assist, the steering hand torque may tend to zero, or the steering hand torque may become heavier. The steering and braking coordination capabilities of the wire-controlled chassis are poor, resulting in low vehicle controllability and safety.

[0005] Therefore, how to improve the steering and braking coordination capabilities of the wire-controlled chassis, thereby improving vehicle handling and safety, is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0006] Based on the above problems, the present application provides a braking force distribution method, device, equipment and storage medium to enhance the steering and braking coordination capabilities of a wire-controlled chassis, thereby improving vehicle handling and safety.

[0007] To solve the above problems, the technical solutions provided in the embodiments of the present application are as follows:

[0008] A method for distributing braking force, the method comprising:

[0009] Acquiring observation input parameters and actual yaw angular velocity, and preprocessing the observation input parameters to obtain preprocessing parameters;

[0010] Calculating an ideal yaw rate according to the preprocessing parameters;

[0011] constructing a feedback control according to the observed input parameter, the actual yaw rate and the ideal yaw rate, and constructing a feedforward control according to the observed input parameter;

[0012] When the vehicle speed of the observed input parameter is less than or equal to a first preset speed, the expected yaw moment is calculated using the feedforward control; when the vehicle speed of the observed input parameter is greater than or equal to a second preset speed, the expected yaw moment is calculated using the feedback control; when the vehicle speed of the observed input parameter is greater than the first preset speed and less than the second preset speed, the expected yaw moment is calculated using a composite control of the feedback control and the feedforward control, wherein the second preset speed is greater than the first preset speed;

[0013] The desired braking force is obtained by distributing the braking force according to the desired yaw moment.

[0014] In a possible implementation, the constructing feedback control according to the observed input parameter, the actual yaw rate and the ideal yaw rate includes:

[0015] Calculating a corrected yaw rate according to the observed input parameter, the actual yaw rate and the ideal yaw rate;

[0016] Calculating a yaw angular velocity error between the actual yaw angular velocity and the corrected yaw angular velocity;

[0017] Feedback control is established according to the swing angular velocity error.

[0018] In a possible implementation, the calculating a corrected yaw rate according to the observed input parameter, the actual yaw rate, and the ideal yaw rate includes:

[0019] When the actual yaw angular velocity is not equal to the ideal yaw angular velocity, the hand-feel simulation actuator angle in the observed input parameter is not equal to the steering actuator angle in the observed input parameter within the first preset time, and the hand-feel simulation actuator speed in the observed input parameter is equal to the maximum characteristic speed of the hand-feel simulation actuator within the second preset time, the change rate of the hand-feel simulation actuator speed is greater than the target change rate, the change amplitude of the hand-feel simulation actuator angle is greater than the target change amplitude, or the vehicle speed is greater than the target vehicle speed, a correction coefficient is obtained according to the vehicle speed;

[0020] Calculating an ideal correction factor based on the correction factor;

[0021] The corrected yaw rate is calculated using a corrected yaw rate formula according to the ideal correction coefficient.

[0022] In a possible implementation, the composite control is:

[0023] T=k*T FF +(1-k)*T PID

[0024] Wherein, T is the composite control; T FF is the feedforward control; T PID is the feedback control; k is a positive integer.

[0025] In a possible implementation, distributing the braking force according to the expected yaw moment includes:

[0026] When the observed input parameter exceeds the observed threshold within a third preset time, the step of distributing the braking force according to the expected yaw moment to obtain the expected braking force is performed.

[0027] In a possible implementation manner, after distributing the braking force according to the expected yaw moment to obtain the expected braking force, the method further includes:

[0028] Get the vehicle's current speed and wheel speed;

[0029] Calculating a slip ratio according to the current vehicle speed and the current wheel speed of the vehicle;

[0030] When the slip ratio is greater than a target slip ratio, the expected braking force is adjusted according to the target slip ratio until the slip ratio is equal to the target slip ratio.

[0031] In a possible implementation, the method further includes:

[0032] When the vehicle speed of the observed input parameter changes from not greater than the first preset speed to not less than the second preset speed or the vehicle speed of the observed input parameter changes from not less than the second preset speed to not greater than the first preset speed, activating the flag;

[0033] The desired yaw moment is calculated by slowly switching from the feedforward control to the feedback control according to a fixed compensation using the flag bit or slowly switching from the feedback control to the feedforward control according to a fixed compensation using the flag bit.

[0034] A braking force distribution device, the device comprising:

[0035] An acquisition preprocessing unit is used to acquire observation input parameters and actual yaw angular velocity, and preprocess the observation input parameters to obtain preprocessing parameters;

[0036] A first calculation unit, configured to calculate an ideal yaw rate according to the preprocessing parameters;

[0037] a constructing unit, configured to construct a feedback control according to the observed input parameter, the actual yaw rate and the ideal yaw rate, and to construct a feedforward control according to the observed input parameter;

[0038] a second calculation unit, for calculating the desired yaw moment by using the feedforward control when the vehicle speed of the observed input parameter is less than or equal to the first preset speed; for calculating the desired yaw moment by using the feedback control when the vehicle speed of the observed input parameter is greater than or equal to the second preset speed; and for calculating the desired yaw moment by using the composite control of the feedback control and the feedforward control when the vehicle speed of the observed input parameter is greater than the first preset speed and less than the second preset speed, wherein the second preset speed is greater than the first preset speed;

[0039] The braking force distribution unit is used to distribute the braking force according to the desired yaw moment to obtain the desired braking force.

[0040] A braking force distribution device comprises a memory and a processor, wherein the memory is used to store programs or codes, and the processor is used to run the programs or codes stored in the memory to implement the braking force distribution method as described above.

[0041] A computer-readable storage medium stores codes. When the codes are executed, a device executing the codes implements the braking force distribution method as described above.

[0042] Compared with the prior art, this application has the following beneficial effects:

[0043] The present application discloses a braking force distribution method, device, equipment and storage medium. Specifically, when executing the braking force distribution method provided in the embodiment of the present application, the observed input parameter and the actual yaw rate are first obtained, and the observed input parameter is preprocessed to obtain the preprocessed parameter. Then the ideal yaw rate is calculated according to the preprocessed parameter. Then the feedback control is constructed according to the observed input parameter, the actual yaw rate and the ideal yaw rate, and the feedforward control is constructed according to the observed input parameter. When the vehicle speed of the observed input parameter is less than or equal to the first preset speed, the expected yaw moment is calculated by feedforward control; when the vehicle speed of the observed input parameter is greater than or equal to the second preset speed, the expected yaw moment is calculated by feedback control; when the vehicle speed of the observed input parameter is greater than the first preset speed and less than the second preset speed, the expected yaw moment is calculated by a composite control of feedback control and feedforward control, wherein the second preset speed is greater than the first preset speed. Finally, the braking force is distributed according to the expected yaw moment to obtain the expected braking force. Based on the observed input parameters, actual yaw rate and ideal yaw rate, it can be determined whether the vehicle is in a state of insufficient / excessive steering, emergency steering and limited steering assistance. Therefore, in this application, corresponding feedback control is constructed based on the observed input parameters, actual yaw rate and ideal yaw rate, and the expected yaw moment is calculated by using feedback control and feedforward control to improve the steering and braking coordination ability of the wire-controlled chassis, thereby improving the vehicle's controllability and safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A flowchart of a braking force distribution method provided in an embodiment of the present application;

[0045] Figure 2 A feedforward control map provided in an embodiment of the present application;

[0046] Figure 3 A typical correction coefficient G provided in the embodiment of the present application i Map diagram;

[0047] Figure 4 A single-wheel cooperative braking control result diagram provided in an embodiment of the present application;

[0048] Figure 5 A schematic diagram of the structure of a braking force distribution device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0049] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0050] To facilitate understanding of the technical solutions provided by the embodiments of the present application, the background technology involved in the embodiments of the present application will be described below.

[0051] With the development of electric and intelligent vehicles, the driving performance and safety of the whole vehicle are becoming more and more important. Based on the software development trend of integrated and modularized chassis, the increasingly mature brake-by-wire and steering-by-wire technologies have made the demand for driving safety more urgent.

[0052] After the vehicle is equipped with a steer-by-wire system, the mechanical hardware's limitation on steering capability limits the vehicle's steering capability when responding to emergency steering and other scenarios. The brake-by-wire system uses independent electrical signals received on the four wheels of the vehicle for independent braking control of the four wheels, which is conducive to coordinated steering / braking control with the chassis domain controller. The lateral and longitudinal coordinated control function is easier to implement in a steer-by-wire chassis system.

[0053] The prior art discloses a variety of methods for using electronically controlled braking to assist steering when the steering assist is insufficient, and controls the vehicle steering by applying direct yaw torque to increase the vehicle steering redundancy. However, in such methods, after the wire-controlled steering system fails and loses assist, the steering hand torque may tend to zero, or the steering hand torque may become heavier. The steering and braking coordination capabilities of the wire-controlled chassis are poor, resulting in low vehicle controllability and safety.

[0054] In order to solve this problem, a braking force distribution method, device, equipment and storage medium are provided in an embodiment of the present application. In the present application, the observed input parameters and the actual yaw rate are first obtained, and the observed input parameters are preprocessed to obtain the preprocessed parameters. Then, the ideal yaw rate is calculated according to the preprocessed parameters, and feedback control is constructed according to the observed input parameters, the actual yaw rate and the ideal yaw rate, and then the feedforward control is constructed according to the observed input parameters. When the vehicle speed of the observed input parameters is less than or equal to the first preset speed, the expected yaw moment is calculated by feedforward control; when the vehicle speed of the observed input parameters is greater than or equal to the second preset speed, the expected yaw moment is calculated by feedback control; when the vehicle speed of the observed input parameters is greater than the first preset speed and less than the second preset speed, the expected yaw moment is calculated by a composite control of feedback control and feedforward control, wherein the second preset speed is greater than the first preset speed. Then, the braking force is distributed according to the expected yaw moment to obtain the expected braking force. Based on the observed input parameters, actual yaw rate and ideal yaw rate, it can be determined whether the vehicle is in a state of insufficient / excessive steering, emergency steering and limited steering assistance. Therefore, in this application, corresponding feedback control is constructed based on the observed input parameters, actual yaw rate and ideal yaw rate, and the expected yaw moment is calculated by using feedback control and feedforward control to improve the steering and braking coordination ability of the wire-controlled chassis, thereby improving the vehicle's controllability and safety.

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0056] See also Figure 1 , which is a flow chart of a braking force distribution method provided in an embodiment of the present application, such as Figure 1 As shown, the braking force distribution method may include steps S101-S105:

[0057] S101: Obtaining observation input parameters and actual yaw angular velocity, and preprocessing the observation input parameters to obtain preprocessing parameters.

[0058] In order to realize the distribution of braking force, the braking force distribution system first needs to obtain the observed input parameters and the actual yaw angular velocity, and preprocess the observed input parameters to obtain preprocessing parameters.

[0059] In a possible implementation, the observed input parameters include but are not limited to the vehicle speed v, the actual yaw rate ω a 、Hand-feel simulation actuator rotation angle δs , feel the simulated actuator speed Steering actuator angle δ w , road adhesion coefficient μ, wheel speed wi, and maximum characteristic speed of the feel simulation actuator

[0060] Vehicle speed v: The speed of a vehicle in motion, usually expressed in kilometers per hour or miles per hour.

[0061] Actual yaw rate ω a : The angular velocity of the vehicle around its vertical axis, usually expressed in radians per second.

[0062] Rotation angle δ of the hand-feel simulation actuator s and speed The actual turning angle (i.e. the turning angle of the steering wheel, etc.) and angular velocity of the tactile simulation actuator used to change the direction of the vehicle.

[0063] Steering actuator angle δ w : The actual turning angle of the vehicle's steering actuator (such as steering gear, drive shaft and other components).

[0064] Road adhesion coefficient μ: The friction coefficient generated by the road surface on the vehicle tires, usually expressed as μ.

[0065] Wheel speed wi: The linear speed at which each wheel of the vehicle rotates, usually expressed in kilometers per hour or miles per hour.

[0066] Maximum characteristic speed of the hand-feeling simulated actuator It refers to the maximum rotation speed that the actuator can achieve under normal operating conditions.

[0067] In a possible implementation, the preprocessing may be implemented by, but is not limited to, using general low-frequency filtering, mean filtering, and other methods.

[0068] S102: Calculating an ideal yaw rate according to the preprocessing parameters.

[0069] After obtaining the observed input parameters, the actual yaw rate and the preprocessing parameters, the braking force distribution system also needs to calculate the ideal yaw rate based on the preprocessing parameters.

[0070] In one possible implementation, the ideal yaw rate w r The calculation formula is:

[0071] Among them, ω r ≤μg / v, L is the wheelbase; v ch is the characteristic speed; v is the vehicle speed; δ s is the steering angle of the actuator simulating the feel; μ is the road adhesion coefficient.

[0072] Characteristic speed refers to the typical or average speed of a vehicle when operating under specific conditions. It can vary depending on the type of vehicle, road conditions, driving style, and other factors. The characteristic speed can vary greatly for different types of vehicles. For example, the characteristic speed of a passenger car on a city road may be affected by traffic congestion and speed limits and is generally low. On the other hand, the characteristic speed of a passenger car on a highway is usually higher and depends on the legal speed limit and flow conditions.

[0073] S103: constructing feedback control according to the observed input parameters, the actual yaw rate and the ideal yaw rate, and constructing feedforward control according to the observed input parameters.

[0074] After calculating the ideal yaw rate according to the preprocessing parameters, the braking force distribution system can construct feedback control according to the observed input parameters, the actual yaw rate and the ideal yaw rate, and construct feedforward control according to the observed input parameters.

[0075] In one possible implementation, the feedforward control T FF The rotation angle δ of the actuator is simulated by the vehicle speed v and the hand feeling s It can be directly concluded that T FF =f(δ s ,v) relationship, such as Figure 2 The feedforward control Map is shown, where n is the steering gear ratio.

[0076] In a possible implementation, the constructing feedback control according to the observed input parameter, the actual yaw rate and the ideal yaw rate includes A1-A3:

[0077] A1: Calculating a corrected yaw rate according to the observed input parameters, the actual yaw rate and the ideal yaw rate.

[0078] In order to construct feedback control according to the observed input parameters, the actual yaw rate and the ideal yaw rate, the braking force distribution system first needs to calculate a corrected yaw rate according to the observed input parameters, the actual yaw rate and the ideal yaw rate.

[0079] In a possible implementation, the calculating the corrected yaw rate according to the observed input parameter, the actual yaw rate and the ideal yaw rate includes B1-B3:

[0080] B1: When the actual yaw angular velocity is not equal to the ideal yaw angular velocity, the feel simulation actuator angle in the observed input parameter is not equal to the steering actuator angle in the observed input parameter within the first preset time and the feel simulation actuator speed in the observed input parameter is equal to the maximum characteristic speed of the feel simulation actuator within the second preset time, the change rate of the feel simulation actuator speed is greater than the target change rate, the change amplitude of the feel simulation actuator angle is greater than the target change amplitude or the vehicle speed is greater than the target speed, obtain the correction coefficient according to the vehicle speed.

[0081] When the actual yaw rate is less than the ideal yaw rate, it means that the vehicle is understeering at this time, and when the actual yaw rate is greater than the ideal yaw rate, it means that the vehicle is oversteering at this time; when the hand-feel simulation actuator angle in the observed input parameter is not equal to the steering actuator angle in the observed input parameter within the first preset time and the hand-feel simulation actuator speed in the observed input parameter within the first preset time is equal to the maximum characteristic speed of the hand-feel simulation actuator, it is judged that the steering assist is limited; when the speed of the hand-feel simulation actuator increases rapidly, the angle is large or the vehicle speed is high, it can be considered that the driver is performing an emergency steering operation. That is to say, when the vehicle is understeering, oversteering, emergency steering or the steering assist is limited, the braking force distribution system can obtain the correction coefficient according to the vehicle speed.

[0082] In a possible implementation, the first preset time may be but is not limited to 200 milliseconds. The present application does not impose any specific limitation on the first preset time, and the user may adjust the first preset time according to actual conditions.

[0083] In a possible implementation, the second preset time may be but is not limited to 100 milliseconds. The present application does not impose any specific limitation on the second preset time, and the user may adjust the second preset time according to actual conditions.

[0084] In a possible implementation, the correction coefficient obtained according to the vehicle speed may be, but is not limited to, obtaining the corresponding correction coefficient according to a map of vehicle speed and correction coefficient. Different correction coefficients are obtained by looking up a table at different vehicle speeds v, such as Figure 3 A typical correction coefficient G provided in the embodiment of the present application i Map diagram, where G1 is the correction coefficient corresponding to the vehicle speed v during understeering and oversteering; G2 is the correction coefficient corresponding to the vehicle speed v during emergency steering; G3 is the correction coefficient corresponding to the vehicle speed v when the steering assist is limited.

[0085] B2: Calculate the ideal correction coefficient G based on the correction coefficient.

[0086] After obtaining the correction coefficient according to the vehicle speed, the braking force distribution system also needs to calculate the ideal correction coefficient G based on the correction coefficient.

[0087] In one possible implementation, the ideal correction factor G=G i / 3.

[0088] B3: Calculate the corrected yaw rate using the corrected yaw rate formula according to the ideal correction coefficient

[0089] After the ideal correction factor G is calculated based on the correction factor, the braking force distribution system can calculate the corrected yaw rate based on the ideal correction factor G and the corrected yaw rate formula.

[0090] In one possible implementation, the ideal yaw rate The calculation formula is:

[0091] Among them, v ch is the characteristic speed, v is the vehicle speed; δ s is the rotation angle of the actuator for tactile simulation; G is the ideal correction coefficient.

[0092] A2: Calculate the actual yaw rate ω a With the modified yaw rate ω r The angular velocity error of the pendulum.

[0093] According to the observed input parameters, the actual yaw angular velocity ω a and the ideal yaw rate ω r Calculate the corrected yaw rate After that, the braking force distribution system needs to calculate the actual yaw rate ω a and the corrected yaw rate The angular velocity error between △ .

[0094] In a possible implementation, the actual yaw angular velocity may be subtracted from the corrected yaw angular velocity to obtain the yaw angular velocity error.

[0095] A3: Construct feedback control based on the swing angular velocity error.

[0096] After calculating the yaw rate error between the actual yaw rate and the corrected yaw rate, the braking force distribution system can construct feedback control according to the yaw rate error.

[0097] In a possible implementation, constructing feedback control based on the yaw rate error usually requires the following steps: (1) Selecting an appropriate control strategy: According to the specific application scenario and system requirements, select an appropriate control strategy, such as proportional control, proportional integral control (PI control), proportional integral differential control (PID control), etc. (2) Setting a target value or expected value: Determine the desired ideal yaw rate or target value as a reference. This can be determined based on pre-set conditions or system requirements. (3) Calculating the control output: Use the controller algorithm to calculate the control output based on the yaw rate error. The specific calculation method depends on the selected control strategy. ① Proportional control (P control): The control output is proportional to the yaw rate error, usually expressed as control output = Kp * yaw rate error, where Kp is the proportional gain parameter. ② Proportional integral control (PI control): In addition to the proportional term, an integral term is also added to eliminate steady-state errors. Control output = Kp * yaw rate error + Ki * integral error, where Ki is the integral gain parameter and the integral error is the accumulated value of the yaw rate error. ③ Proportional-integral-differential control (PID control): Based on proportional control and integral control, a differential term is added to respond to the rate of change of the system. Control output = Kp*swing angular velocity error + Ki*integral error + Kd*differential error, where Kd is the differential gain parameter and the differential error is the rate of change of the swing angular velocity error. (4) Apply control output: Apply the calculated control output to the system, for example, by adjusting the lateral force or control input, so that the system tends to the ideal yaw angular velocity. (5) Iterative optimization: Iterative optimization is performed based on the actual effect and system response, and the control parameters are adjusted to obtain better control performance. Parameter adjustment can be performed using trial and error, self-tuning, and other methods.

[0098] S104: When the vehicle speed of the observed input parameter is less than or equal to the first preset speed, the expected yaw moment is calculated using the feedforward control; when the vehicle speed of the observed input parameter is greater than or equal to the second preset speed, the expected yaw moment is calculated using the feedback control; when the vehicle speed of the observed input parameter is greater than the first preset speed and less than the second preset speed, the expected yaw moment is calculated using the composite control of the feedback control and the feedforward control, wherein the second preset speed is greater than the first preset speed.

[0099] After obtaining feedback control and feedforward control, a suitable control method can be selected according to the vehicle speed to calculate the expected yaw moment. When the vehicle speed of the observed input parameter is less than or equal to the first preset speed, the expected yaw moment is calculated using feedforward control; when the vehicle speed of the observed input parameter is greater than or equal to the second preset speed, the expected yaw moment is calculated using feedback control; when the vehicle speed of the observed input parameter is greater than the first preset speed and less than the second preset speed, the expected yaw moment is calculated using a composite control of feedback control and feedforward control, wherein the second preset speed is greater than the first preset speed.

[0100] In a possible implementation, the present application does not impose any specific restrictions on the first preset vehicle speed, and the user can set the first preset vehicle speed according to actual conditions.

[0101] In a possible implementation, the present application does not impose any specific restrictions on the second preset vehicle speed, and the user can set the second preset vehicle speed according to actual conditions.

[0102] In a possible implementation, the composite control is:

[0103] T=k*T FF +(1-k)*T PID

[0104] Wherein, T is the composite control; T FF is the feedforward control; T PID is the feedback control; k is a positive integer. k can be set by the user according to actual conditions.

[0105] S105: Distribute the braking force according to the desired yaw moment to obtain the desired braking force.

[0106] After the expected yaw moment is calculated, the braking force can be distributed according to the expected yaw moment to obtain the expected braking force.

[0107] Based on the desired yaw moment and vehicle state, a brake force distribution algorithm is used to calculate the desired braking force on the inner rear wheel.

[0108] See also Figure 4 , Figure 4A single-wheel cooperative braking control result diagram provided for an embodiment of the present application. The working condition is set as: vehicle speed 10kph, front wheel turning angle of 15° right turn, and a real vehicle uniformly circling scene with a fault in the wire-controlled steering system. Among them, YawRateRef refers to the desired yaw rate of the vehicle (Yaw Rate Reference), which indicates the target yaw rate that the vehicle expects to achieve under specific driving conditions; YawRateAct refers to the actual yaw rate of the vehicle (ActualYaw Rate), which indicates the actual measured yaw rate of the vehicle, that is, the current rotation rate of the vehicle. VehSpd refers to the vehicle speed, that is, the actual speed of the vehicle. It indicates the vehicle's driving speed at a certain moment ( Figure 4 RefPressRR is the right turn angle (the current right turn angle is 15 degrees), and ActPressRR is the actual power.

[0109] In a possible implementation, distributing the braking force according to the expected yaw moment includes:

[0110] When the observed input parameter exceeds the observed threshold within a third preset time, the step of distributing the braking force according to the expected yaw moment to obtain the expected braking force is performed.

[0111] When the observed input parameter exceeds the observed threshold value within a certain time (ie, the third preset time), the step of distributing the braking force according to the expected yaw moment to obtain the expected braking force is executed.

[0112] In a possible implementation, when the observed input parameter exceeds the observed threshold within a third preset time, performing the step of distributing the braking force according to the expected yaw moment to obtain the expected braking force specifically includes:

[0113] If the actual yaw angular velocity is not equal to the ideal yaw angular velocity within the fourth preset time; the feel simulation actuator angle in the observed input parameter is not equal to the steering actuator angle in the observed input parameter within the first preset time and the feel simulation actuator speed in the observed input parameter is equal to the maximum characteristic speed of the feel simulation actuator within the second preset time; the rate of change of the feel simulation actuator speed within the fifth preset time is greater than the target change rate, the amplitude of change of the feel simulation actuator angle is greater than the target amplitude, and the vehicle speed in the observed input parameter is greater than the target vehicle speed, any one of the following is satisfied, the braking force distribution according to the expected yaw moment is executed.

[0114] There are two cases where the actual yaw rate is not equal to the ideal yaw rate within the fourth preset time: ① when the actual yaw rate is less than the ideal yaw rate, it means that the vehicle is understeering and needs to further increase the yaw rate, and this situation is judged as understeering. ② when the actual yaw rate is greater than the ideal yaw rate, it means that the vehicle is oversteering and needs to further reduce the yaw rate, and this situation is judged as oversteering.

[0115] When it is simultaneously satisfied that the hand-feel simulation actuator angle in the observed input parameter within the first preset time is not equal to the steering actuator angle in the observed input parameter and the hand-feel simulation actuator speed in the observed input parameter within the second preset time is equal to the maximum characteristic speed of the hand-feel simulation actuator, this situation is judged as limited steering assistance.

[0116] When the change rate of the rotation speed of the hand-feel simulation actuator within the fifth preset time is greater than the target change rate, the change amplitude of the rotation angle of the hand-feel simulation actuator is greater than the target change amplitude, and the vehicle speed in the observed input parameter is greater than the target vehicle speed, this situation is judged as the driver is performing an emergency steering operation.

[0117] For example, when the understeering condition is met and lasts for 220ms, or the steering assist limited condition is met and lasts for 150ms, or the emergency steering condition is met and lasts for 50ms, the braking force can be distributed directly according to the expected yaw moment.

[0118] In a possible implementation, the fourth preset time may be but is not limited to 220 milliseconds. The present application does not impose any specific limitation on the fourth preset time, and the user may adjust the fourth preset time according to actual conditions.

[0119] In a possible implementation, the fifth preset time may be but is not limited to 150 milliseconds. The present application does not impose any specific limitation on the fifth preset time, and the user may adjust the fifth preset time according to actual conditions.

[0120] In a possible implementation, after distributing the braking force according to the expected yaw moment to obtain the expected braking force, C1-C3 are further included:

[0121] C1: Get the current vehicle speed and wheel speed.

[0122] In order to improve driving safety, handling performance and energy efficiency, the braking force distribution system first needs to obtain the vehicle's current speed and the vehicle's current wheel speed.

[0123] The current vehicle speed and the current wheel speed of the vehicle refer to the vehicle's driving speed and the vehicle's wheel speed after the vehicle distributes the braking force according to the desired yaw moment to obtain the desired braking force.

[0124] C2: Calculating the slip ratio according to the current vehicle speed and the current wheel speed of the vehicle.

[0125] After obtaining the current vehicle speed and the current wheel speed of the vehicle, the braking force distribution system also needs to calculate the slip rate based on the current vehicle speed and the current wheel speed of the vehicle.

[0126] In one possible implementation, the slip ratio σ i The current vehicle speed v1 and the current wheel speed ω d Calculate,σ i =(v1-ω d *R) / v, where R is the tire radius.

[0127] C3: when the slip ratio is greater than a target slip ratio, adjusting the expected braking force according to the target slip ratio until the slip ratio is equal to the target slip ratio.

[0128] When the slip ratio is greater than the target slip ratio, the braking force distribution system may adjust the expected braking force according to the target slip ratio until the slip ratio is equal to the target slip ratio.

[0129] In a possible implementation, the target slip ratio may be set between 10% and 30%. A slip ratio that is too low may result in a too long braking distance or poor braking effect, while a slip ratio that is too high may result in vehicle loss of control or excessive braking.

[0130] The specific slip ratio setting should be determined according to the vehicle's suspension system, tire performance, road conditions, driving style, and required handling performance. For ordinary passenger cars, it is generally recommended to set the slip ratio between 15% and 25%, which can provide good braking effect and handling stability.

[0131] However, for high-performance racing or special driving conditions (such as track driving), the slip ratio may be set higher to provide stronger braking force and handling performance.

[0132] In short, the present application does not impose any specific restrictions on the target slip ratio, and the user can adjust the target slip ratio according to actual conditions.

[0133] In a possible implementation, the adjustment of the expected braking force according to the target slip ratio until the slip ratio is equal to the target slip ratio can be achieved by the following steps: (1) First, determine the difference between the current slip ratio and the target slip ratio (i.e., the slip ratio deviation). (2) Determine the way to adjust the expected braking force according to the direction of the slip ratio deviation. If the slip ratio deviation is positive (the current slip ratio is greater than the target slip ratio), the expected braking force needs to be reduced; if the slip ratio deviation is negative (the current slip ratio is less than the target slip ratio), the expected braking force needs to be increased. (3) According to the size of the slip ratio deviation, gradually adjust the expected braking force. An iterative or gradual adjustment method can be used, with a small step each time until the slip ratio approaches the target slip ratio. (4) After each adjustment of the braking force, observe the change in the slip ratio and make further adjustments as needed until the slip ratio reaches the target slip ratio.

[0134] It should be noted that the vehicle and driving conditions should be fully considered when making adjustments. Too much or too little braking force adjustment may lead to unstable braking effect or reduced handling performance. Therefore, in actual application, it is recommended to make appropriate adjustments based on actual driving experience and conditions and follow the principles of safe driving.

[0135] In one possible implementation, when understeering occurs in a left turn, when the actual braking force of the left rear wheel reaches the braking force that satisfies the maximum slip rate of 30%, the braking force of the left rear wheel cannot be further increased. At this time, the braking force of the left front wheel can be slightly increased. When understeering occurs in a left turn, that is, when the braking force of the left rear wheel has reached the braking force that satisfies the maximum slip rate of 30%, increasing the braking force of the left front wheel can improve the steering performance of the left turn. This is because by increasing the braking force of the left front wheel, the grip of the left front wheel with the ground can be improved, so that it can provide more rotational torque to help the vehicle complete the left turn operation.

[0136] However, increasing the braking force of the left front wheel will also increase the slip rate of that wheel. Therefore, when adjusting the braking force of the left front wheel, the slip rate needs to be controlled according to the specific situation to avoid exceeding the safety range. If the slip rate is too high, it may cause the vehicle to lose control or brake instability.

[0137] The slip rate is inversely proportional to the vehicle speed. For example, when the vehicle speed is 30 kph (kilometers per hour), the target slip rate is 40%; when the vehicle speed is 100 kph, the target slip rate is 15%).

[0138] In a possible implementation, the method further includes D1-D2:

[0139] D1: When the vehicle speed of the observed input parameter is converted from not greater than the first preset speed to not less than the second preset speed or the vehicle speed of the observed input parameter is converted from not less than the second preset speed to not greater than the first preset speed, the flag is activated.

[0140] When the speed of the vehicle changes, the braking and steering performance will be affected. Therefore, when adjusting the expected yaw moment, it is necessary to flexibly adjust it according to the actual motion state of the vehicle to obtain a better control effect. Therefore, the braking force distribution system can activate the flag when the vehicle speed of the observed input parameter changes from not greater than the first preset speed to not less than the second preset speed or when the vehicle speed of the observed input parameter changes from not less than the second preset speed to not greater than the first preset speed.

[0141] In a possible implementation, the present application does not impose any specific restrictions on the first preset vehicle speed, and the user can set the first preset vehicle speed according to actual conditions.

[0142] In a possible implementation, the present application does not impose any specific restrictions on the second preset vehicle speed, and the user can set the second preset vehicle speed according to actual conditions.

[0143] In a possible implementation, a flag is a variable that is used to represent a certain state or condition. In this case, the flag is used to indicate whether the speed of the vehicle is within a preset range.

[0144] D2: Calculate the desired yaw moment by slowly switching from the feedforward control to the feedback control according to a fixed compensation using the flag or slowly switching from the feedback control to the feedforward control according to a fixed compensation using the flag.

[0145] By using the flag bit to slowly switch from feedforward control to feedback control or from feedback control to feedforward control according to fixed compensation, the appropriate control strategy can be automatically selected according to the change of vehicle speed. When the vehicle speed is low, feedforward control is more suitable than feedback control; when the vehicle speed is high, feedback control is more effective. By automatically switching the control strategy, it can be ensured that the control strategy switches smoothly between the first preset vehicle speed and the second preset vehicle speed.

[0146] In a possible implementation, the calculation of the desired yaw moment by slowly switching from the feedforward control to the feedback control according to a fixed compensation using the flag bit or slowly switching from the feedback control to the feedforward control according to a fixed compensation using the flag bit can be implemented in the following manner: (1) Determine the flag bit: First, you need to determine a flag bit or a switch to indicate whether feedforward control or feedback control should be used. For example, a Boolean variable or other appropriate flag bit can be used. (2) Set the compensation value: Determine the compensation value provided by the feedforward control or feedback control. This compensation value can be determined based on the specific control algorithm and system characteristics. (3) Switch the control mode: Switch the control mode based on the state of the flag bit. If the flag bit is true, the feedforward control mode is selected; if the flag bit is false, the feedback control mode is selected. (4) Calculate the desired yaw moment: Based on the selected control mode, the desired yaw moment is calculated using the corresponding compensation value and other relevant parameters. This calculation process will depend on the specific control system and algorithm.

[0147] Based on the contents of S101-S105, it can be known that the observed input parameters and the actual yaw rate are first obtained, and the observed input parameters are preprocessed to obtain the preprocessed parameters. Then the ideal yaw rate is calculated according to the preprocessed parameters, and feedback control is constructed according to the observed input parameters, the actual yaw rate and the ideal yaw rate, and then the feedforward control is constructed according to the observed input parameters. When the vehicle speed of the observed input parameters is less than or equal to the first preset speed, the expected yaw moment is calculated by feedforward control; when the vehicle speed of the observed input parameters is greater than or equal to the second preset speed, the expected yaw moment is calculated by feedback control; when the vehicle speed of the observed input parameters is greater than the first preset speed and less than the second preset speed, the expected yaw moment is calculated by a composite control of feedback control and feedforward control, wherein the second preset speed is greater than the first preset speed. Finally, the braking force is distributed according to the expected yaw moment to obtain the expected braking force. Based on the observed input parameters, actual yaw rate and ideal yaw rate, it can be determined whether the vehicle is in a state of insufficient / excessive steering, emergency steering and limited steering assistance. Therefore, in this application, corresponding feedback control is constructed based on the observed input parameters, actual yaw rate and ideal yaw rate, and the expected yaw moment is calculated by using feedback control and feedforward control to improve the steering and braking coordination ability of the wire-controlled chassis, thereby improving the vehicle's controllability and safety.

[0148] See also Figure 5 , which is a schematic diagram of the structure of a braking force distribution device provided in an embodiment of the present application. Figure 5 As shown, the braking force distribution device includes:

[0149] The acquisition preprocessing unit 501 is used to acquire observation input parameters and actual yaw angular velocity, and preprocess the observation input parameters to obtain preprocessing parameters.

[0150] In a possible implementation, the observed input parameters include but are not limited to the vehicle speed v, the actual yaw rate ω a 、Hand-feel simulation actuator rotation angle δ s , feel the simulated actuator speed Steering actuator angle δ w , road adhesion coefficient μ, wheel speed w i And the maximum characteristic speed of the simulated actuator

[0151] Vehicle speed v: The speed of a vehicle in motion, usually expressed in kilometers per hour or miles per hour.

[0152] Actual yaw rate ω a : The angular velocity of the vehicle around its vertical axis, usually expressed in radians per second.

[0153] Rotation angle δ of the hand-feel simulation actuator s and speed The actual turning angle (i.e. the turning angle of the steering wheel, etc.) and angular velocity of the tactile simulation actuator used to change the direction of the vehicle.

[0154] Steering actuator angle δ w : The actual turning angle of the vehicle's steering actuator (such as steering gear, drive shaft and other components).

[0155] Road adhesion coefficient μ: The friction coefficient generated by the road surface on the vehicle tires, usually expressed as μ.

[0156] Wheel speed i : The linear speed at which the vehicle's wheels rotate, usually expressed in kilometers per hour or miles per hour.

[0157] Maximum characteristic speed of the hand-feeling simulated actuator It refers to the maximum rotation speed that the actuator can achieve under normal operating conditions.

[0158] In a possible implementation, the preprocessing may be implemented by, but is not limited to, using general low-frequency filtering, mean filtering, and other methods.

[0159] The first calculation unit 502 is used to calculate an ideal yaw rate according to the preprocessing parameters.

[0160] In one possible implementation, the ideal yaw rate w r The calculation formula is:

[0161] Among them, ω r ≤μg / v, L is the wheelbase; v ch is the characteristic speed; v is the vehicle speed; δ s is the steering angle of the actuator simulating the feel; μ is the road adhesion coefficient.

[0162] Characteristic speed refers to the typical or average speed of a vehicle when operating under specific conditions. It can vary depending on the type of vehicle, road conditions, driving style, and other factors. The characteristic speed can vary greatly for different types of vehicles. For example, the characteristic speed of a passenger car on a city road may be affected by traffic congestion and speed limits and is generally low. On the other hand, the characteristic speed of a passenger car on a highway is usually higher and depends on the legal speed limit and flow conditions.

[0163] The first constructing unit 503 is used to construct feedback control according to the observed input parameters, the actual yaw rate and the ideal yaw rate, and to construct feedforward control according to the observed input parameters.

[0164] In one possible implementation, the feedforward control T FF The rotation angle δ of the actuator is simulated by the vehicle speed v and the hand feeling s It can be directly concluded that T FF =f(δ s ,v) relationship, such as Figure 2 The feedforward control Map is shown, where n is the steering gear ratio.

[0165] The second calculation unit 504 is used to calculate the expected yaw moment using the feedforward control when the vehicle speed of the observed input parameter is less than or equal to the first preset speed; to calculate the expected yaw moment using the feedback control when the vehicle speed of the observed input parameter is greater than or equal to the second preset speed; and to calculate the expected yaw moment using the composite control of the feedback control and the feedforward control when the vehicle speed of the observed input parameter is greater than the first preset speed and less than the second preset speed, wherein the second preset speed is greater than the first preset speed.

[0166] In a possible implementation, the present application does not impose any specific restrictions on the first preset vehicle speed, and the user can set the first preset vehicle speed according to actual conditions.

[0167] In a possible implementation, the present application does not impose any specific restrictions on the second preset vehicle speed, and the user can set the second preset vehicle speed according to actual conditions.

[0168] In a possible implementation, the composite control is:

[0169] T=k*T FF+(1-k)*T PID

[0170] Wherein, T is the composite control; T FF is the feedforward control; T PID is the feedback control; k is a positive integer. k can be set by the user according to actual conditions.

[0171] The braking force distribution unit 505 is used to distribute the braking force according to the desired yaw moment to obtain the desired braking force.

[0172] See also Figure 4 , Figure 4 A single-wheel cooperative braking control result diagram provided for an embodiment of the present application. The working condition is set as: vehicle speed 10kph, front wheel turning angle of 15° right turn, and a real vehicle uniformly circling scene with a fault in the wire-controlled steering system. Among them, YawRateRef refers to the desired yaw rate of the vehicle (Yaw Rate Reference), which indicates the target yaw rate that the vehicle expects to achieve under specific driving conditions; YawRateAct refers to the actual yaw rate of the vehicle (ActualYaw Rate), which indicates the actual measured yaw rate of the vehicle, that is, the current rotation rate of the vehicle. VehSpd refers to the vehicle speed, that is, the actual speed of the vehicle. It indicates the vehicle's driving speed at a certain moment ( Figure 4 RefPressRR is the right turn angle (the current right turn angle is 15 degrees), and ActPressRR is the actual power.

[0173] In a possible implementation manner, the device further includes:

[0174] The correction unit is used to calculate a corrected yaw rate according to the observed input parameter, the actual yaw rate and the ideal yaw rate.

[0175] When the actual yaw rate is less than the ideal yaw rate, it means that the vehicle is understeering at this time, and when the actual yaw rate is greater than the ideal yaw rate, it means that the vehicle is oversteering at this time; when the hand-feel simulation actuator angle in the observed input parameter is not equal to the steering actuator angle in the observed input parameter within the first preset time and the hand-feel simulation actuator speed in the observed input parameter within the first preset time is equal to the maximum characteristic speed of the hand-feel simulation actuator, it is judged that the steering assist is limited; when the speed of the hand-feel simulation actuator increases rapidly, the angle is large or the vehicle speed is high, it can be considered that the driver is performing an emergency steering operation. That is to say, when the vehicle is understeering, oversteering, emergency steering or the steering assist is limited, the braking force distribution system can obtain the correction coefficient according to the vehicle speed.

[0176] In a possible implementation, the first preset time may be but is not limited to 200 milliseconds. The present application does not impose any specific limitation on the first preset time, and the user may adjust the first preset time according to actual conditions.

[0177] In a possible implementation, the second preset time may be but is not limited to 100 milliseconds. The present application does not impose any specific limitation on the second preset time, and the user may adjust the second preset time according to actual conditions.

[0178] In a possible implementation, the correction coefficient obtained according to the vehicle speed may be, but is not limited to, obtaining the corresponding correction coefficient according to a map of vehicle speed and correction coefficient. Different correction coefficients are obtained by looking up a table at different vehicle speeds v, such as Figure 3 A typical correction coefficient G provided in the embodiment of the present application i Map diagram, where G1 is the correction coefficient corresponding to the vehicle speed v during understeering and oversteering; G2 is the correction coefficient corresponding to the vehicle speed v during emergency steering; G3 is the correction coefficient corresponding to the vehicle speed v when the steering assist is limited.

[0179] The third calculation unit is used to calculate a yaw angular velocity error between the actual yaw angular velocity and the corrected yaw angular velocity.

[0180] In one possible implementation, the ideal correction factor G=G i / 3.

[0181] The second constructing unit is used to construct feedback control according to the swing angular velocity error.

[0182] In one possible implementation, the ideal yaw rate The calculation formula is:

[0183] Among them, v ch is the characteristic speed, v is the vehicle speed; δ s is the rotation angle of the actuator for tactile simulation; G is the ideal correction coefficient.

[0184] In a possible implementation manner, the device further includes:

[0185] The first acquisition unit is used to obtain the correction coefficient according to the vehicle speed when the actual yaw angular velocity is not equal to the ideal yaw angular velocity, the feel simulation actuator angle in the observed input parameter is not equal to the steering actuator angle in the observed input parameter within the first preset time and the feel simulation actuator speed in the observed input parameter is equal to the maximum characteristic speed of the feel simulation actuator within the second preset time, the change rate of the feel simulation actuator speed is greater than the target change rate, the change amplitude of the feel simulation actuator angle is greater than the target change amplitude or the vehicle speed is greater than the target speed.

[0186] When the actual yaw rate is less than the ideal yaw rate, it means that the vehicle is understeering at this time, and when the actual yaw rate is greater than the ideal yaw rate, it means that the vehicle is oversteering at this time; when the hand-feel simulation actuator angle in the observed input parameter is not equal to the steering actuator angle in the observed input parameter within the first preset time and the hand-feel simulation actuator speed in the observed input parameter within the first preset time is equal to the maximum characteristic speed of the hand-feel simulation actuator, it is determined that the steering assist is limited; when the speed of the hand-feel simulation actuator increases rapidly, the angle is large or the vehicle speed is high, it can be considered that the driver is performing an emergency steering operation. That is to say, when the vehicle is understeering, oversteering, emergency steering or the steering assist is limited, the first acquisition unit can obtain the correction coefficient according to the vehicle speed.

[0187] In a possible implementation, the first preset time may be but is not limited to 200 milliseconds. The present application does not impose any specific limitation on the first preset time, and the user may adjust the first preset time according to actual conditions.

[0188] In a possible implementation, the second preset time may be but is not limited to 100 milliseconds. The present application does not impose any specific limitation on the second preset time, and the user may adjust the second preset time according to actual conditions.

[0189] In a possible implementation, the correction coefficient obtained according to the vehicle speed may be, but is not limited to, obtaining the corresponding correction coefficient according to a map of vehicle speed and correction coefficient. Different correction coefficients are obtained by looking up a table at different vehicle speeds v, such as Figure 3 A typical correction coefficient G provided in the embodiment of the present application i Map diagram, where G1 is the correction coefficient corresponding to the vehicle speed v during understeering and oversteering; G2 is the correction coefficient corresponding to the vehicle speed v during emergency steering; G3 is the correction coefficient corresponding to the vehicle speed v when the steering assist is limited.

[0190] The fourth calculation unit is used to calculate an ideal correction coefficient according to the correction coefficient.

[0191] In one possible implementation, the ideal correction factor G=G i / 3.

[0192] A fifth calculation unit is used to calculate the corrected yaw rate using a corrected yaw rate formula according to the ideal correction coefficient.

[0193] In one possible implementation, the ideal yaw rate The calculation formula is:

[0194] Among them, v ch is the characteristic speed, v is the vehicle speed; δ s is the rotation angle of the actuator for tactile simulation; G is the ideal correction coefficient.

[0195] In a possible implementation manner, the device further includes:

[0196] An execution unit is used for executing the step of distributing the braking force according to the expected yaw moment to obtain the expected braking force when the observed input parameter exceeds an observation threshold within a third preset time.

[0197] In a possible implementation, when the observed input parameter exceeds the observed threshold within a third preset time, performing the step of distributing the braking force according to the expected yaw moment to obtain the expected braking force specifically includes:

[0198] If the actual yaw angular velocity is not equal to the ideal yaw angular velocity within the fourth preset time; the feel simulation actuator angle in the observed input parameter is not equal to the steering actuator angle in the observed input parameter within the first preset time and the feel simulation actuator speed in the observed input parameter is equal to the maximum characteristic speed of the feel simulation actuator within the second preset time; the rate of change of the feel simulation actuator speed within the fifth preset time is greater than the target change rate, the amplitude of change of the feel simulation actuator angle is greater than the target amplitude, and the vehicle speed in the observed input parameter is greater than the target vehicle speed, any one of the following is satisfied, the braking force distribution according to the expected yaw moment is executed.

[0199] There are two cases where the actual yaw rate is not equal to the ideal yaw rate within the fourth preset time: ① when the actual yaw rate is less than the ideal yaw rate, it means that the vehicle is understeering and needs to further increase the yaw rate, and this situation is judged as understeering. ② when the actual yaw rate is greater than the ideal yaw rate, it means that the vehicle is oversteering and needs to further reduce the yaw rate, and this situation is judged as oversteering.

[0200] When it is simultaneously satisfied that the hand-feel simulation actuator angle in the observed input parameter within the first preset time is not equal to the steering actuator angle in the observed input parameter and the hand-feel simulation actuator speed in the observed input parameter within the second preset time is equal to the maximum characteristic speed of the hand-feel simulation actuator, this situation is judged as limited steering assistance.

[0201] When the change rate of the rotation speed of the hand-feel simulation actuator within the fifth preset time is greater than the target change rate, the change amplitude of the rotation angle of the hand-feel simulation actuator is greater than the target change amplitude, and the vehicle speed in the observed input parameter is greater than the target vehicle speed, this situation is judged as the driver is performing an emergency steering operation.

[0202] For example, when the understeering condition is met and lasts for 220ms, or the steering assist limited condition is met and lasts for 150ms, or the emergency steering condition is met and lasts for 50ms, the braking force can be distributed directly according to the expected yaw moment.

[0203] In a possible implementation, the fourth preset time may be but is not limited to 220 milliseconds. The present application does not impose any specific limitation on the fourth preset time, and the user may adjust the fourth preset time according to actual conditions.

[0204] In a possible implementation, the fifth preset time may be but is not limited to 150 milliseconds. The present application does not impose any specific limitation on the fifth preset time, and the user may adjust the fifth preset time according to actual conditions.

[0205] In a possible implementation manner, the device further includes:

[0206] The second acquisition unit is used to acquire the current vehicle speed and the current wheel speed of the vehicle.

[0207] The current vehicle speed and the current wheel speed of the vehicle refer to the vehicle's driving speed and the vehicle's wheel speed after the vehicle distributes the braking force according to the desired yaw moment to obtain the desired braking force.

[0208] The calculation unit is used to calculate the slip rate according to the current vehicle speed and the current wheel speed of the vehicle.

[0209] In one possible implementation, the slip ratio σ i The current vehicle speed v1 and the current wheel speed ω d Calculate,σ i =(v1-ω d *R) / v, where R is the tire radius.

[0210] The sixth unit is configured to adjust the expected braking force according to the target slip ratio until the slip ratio is equal to the target slip ratio when the slip ratio is greater than the target slip ratio.

[0211] In a possible implementation, the target slip ratio may be set between 10% and 30%. A slip ratio that is too low may result in a too long braking distance or poor braking effect, while a slip ratio that is too high may result in vehicle loss of control or excessive braking.

[0212] The specific slip ratio setting should be determined according to the vehicle's suspension system, tire performance, road conditions, driving style, and required handling performance. For ordinary passenger cars, it is generally recommended to set the slip ratio between 15% and 25%, which can provide good braking effect and handling stability.

[0213] However, for high-performance racing or special driving conditions (such as track driving), the slip ratio may be set higher to provide stronger braking force and handling performance.

[0214] In short, the present application does not impose any specific restrictions on the target slip ratio, and the user can adjust the target slip ratio according to actual conditions.

[0215] In a possible implementation, the adjustment of the expected braking force according to the target slip ratio until the slip ratio is equal to the target slip ratio can be achieved by the following steps: (1) First, determine the difference between the current slip ratio and the target slip ratio (i.e., the slip ratio deviation). (2) Determine the way to adjust the expected braking force according to the direction of the slip ratio deviation. If the slip ratio deviation is positive (the current slip ratio is greater than the target slip ratio), the expected braking force needs to be reduced; if the slip ratio deviation is negative (the current slip ratio is less than the target slip ratio), the expected braking force needs to be increased. (3) According to the size of the slip ratio deviation, gradually adjust the expected braking force. An iterative or gradual adjustment method can be used, with a small step each time until the slip ratio approaches the target slip ratio. (4) After each adjustment of the braking force, observe the change in the slip ratio and make further adjustments as needed until the slip ratio reaches the target slip ratio.

[0216] It should be noted that the vehicle and driving conditions should be fully considered when making adjustments. Too much or too little braking force adjustment may lead to unstable braking effect or reduced handling performance. Therefore, in actual application, it is recommended to make appropriate adjustments based on actual driving experience and conditions and follow the principles of safe driving.

[0217] In one possible implementation, when understeering occurs in a left turn, when the actual braking force of the left rear wheel reaches the braking force that satisfies the maximum slip rate of 30%, the braking force of the left rear wheel cannot be further increased. At this time, the braking force of the left front wheel can be slightly increased. When understeering occurs in a left turn, that is, when the braking force of the left rear wheel has reached the braking force that satisfies the maximum slip rate of 30%, increasing the braking force of the left front wheel can improve the steering performance of the left turn. This is because by increasing the braking force of the left front wheel, the grip of the left front wheel with the ground can be improved, so that it can provide more rotational torque to help the vehicle complete the left turn operation.

[0218] However, increasing the braking force of the left front wheel will also increase the slip rate of that wheel. Therefore, when adjusting the braking force of the left front wheel, the slip rate needs to be controlled according to the specific situation to avoid exceeding the safety range. If the slip rate is too high, it may cause the vehicle to lose control or brake instability.

[0219] The slip rate is inversely proportional to the vehicle speed. For example, when the vehicle speed is 30 kph (kilometers per hour), the target slip rate is 40%; when the vehicle speed is 100 kph, the target slip rate is 15%).

[0220] In a possible implementation manner, the device further includes:

[0221] An activation unit is used to activate a flag when the vehicle speed of the observed input parameter is converted from not greater than a first preset speed to not less than a second preset speed or when the vehicle speed of the observed input parameter is converted from not less than the second preset speed to not greater than the first preset speed.

[0222] In a possible implementation, a flag is a variable that is used to represent a certain state or condition. In this case, the flag is used to indicate whether the speed of the vehicle is within a preset range.

[0223] A switching unit is used to calculate the desired yaw moment by slowly switching from the feedforward control to the feedback control according to a fixed compensation using the flag bit or slowly switching from the feedback control to the feedforward control according to a fixed compensation using the flag bit.

[0224] In a possible implementation, the calculation of the desired yaw moment by slowly switching from the feedforward control to the feedback control according to a fixed compensation using the flag bit or slowly switching from the feedback control to the feedforward control according to a fixed compensation using the flag bit can be implemented in the following manner: (1) Determine the flag bit: First, you need to determine a flag bit or a switch to indicate whether feedforward control or feedback control should be used. For example, a Boolean variable or other appropriate flag bit can be used. (2) Set the compensation value: Determine the compensation value provided by the feedforward control or feedback control. This compensation value can be determined based on the specific control algorithm and system characteristics. (3) Switch the control mode: Switch the control mode based on the state of the flag bit. If the flag bit is true, the feedforward control mode is selected; if the flag bit is false, the feedback control mode is selected. (4) Calculate the desired yaw moment: Based on the selected control mode, the desired yaw moment is calculated using the corresponding compensation value and other relevant parameters. This calculation process will depend on the specific control system and algorithm.

[0225] In addition, an embodiment of the present application also provides a braking force distribution device, which includes a memory and a processor, the memory is used to store programs or codes, and the processor is used to run the programs or codes stored in the memory to implement the above-mentioned braking force distribution method.

[0226] In addition, an embodiment of the present application further provides a computer-readable storage medium, characterized in that a code is stored in the computer-readable storage medium, and when the code is executed, the device executing the code implements the above-mentioned braking force distribution method.

[0227] The embodiment of the present application provides a braking force distribution device. First, when receiving a network request sent by a business layer, the observed input parameter and the actual yaw rate can be obtained by using the acquisition preprocessing unit 501, and the observed input parameter is preprocessed to obtain the preprocessing parameter. Then, the ideal yaw rate is calculated according to the preprocessing parameter by the first calculation unit 502, and the feedback control is constructed according to the observed input parameter, the actual yaw rate and the ideal yaw rate by the first construction unit 503, and the feedforward control is constructed according to the observed input parameter. Then, when the vehicle speed of the observed input parameter is less than or equal to the first preset speed, the desired yaw moment is calculated by the second calculation unit 504 by using the feedforward control; when the vehicle speed of the observed input parameter is greater than or equal to the second preset speed, the desired yaw moment is calculated by the feedback control of the second calculation unit 504; when the vehicle speed of the observed input parameter is greater than the first preset speed and less than the second preset speed, the desired yaw moment is calculated by the second calculation unit 504 by using the composite control of the feedback control and the feedforward control, wherein the second preset speed is greater than the first preset speed. Finally, when the expected yaw moment is calculated, the braking force distribution unit 505 distributes the braking force according to the expected yaw moment to obtain the expected braking force. According to the observed input parameters, the actual yaw angular velocity and the ideal yaw angular velocity, it can be judged whether the vehicle is in a state of insufficient / excessive steering, emergency steering and limited steering assistance. Therefore, in this application, the corresponding feedback control is constructed according to the observed input parameters, the actual yaw angular velocity and the ideal yaw angular velocity, and the expected yaw moment is calculated by using feedback control and feedforward control to improve the steering and braking coordination ability of the wire-controlled chassis, thereby improving the vehicle controllability and safety.

[0228] It should be understood that in the present application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0229] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0230] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0231] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for distributing braking force, characterized in that: The method comprises: Acquiring observation input parameters and actual yaw angular velocity, and preprocessing the observation input parameters to obtain preprocessing parameters; Calculating an ideal yaw rate according to the preprocessing parameters; constructing a feedback control according to the observed input parameter, the actual yaw rate and the ideal yaw rate, and constructing a feedforward control according to the observed input parameter; When the vehicle speed of the observed input parameter is less than or equal to a first preset speed, the expected yaw moment is calculated using the feedforward control; when the vehicle speed of the observed input parameter is greater than or equal to a second preset speed, the expected yaw moment is calculated using the feedback control; when the vehicle speed of the observed input parameter is greater than the first preset speed and less than the second preset speed, the expected yaw moment is calculated using a composite control of the feedback control and the feedforward control, wherein the second preset speed is greater than the first preset speed; The desired braking force is obtained by distributing the braking force according to the desired yaw moment.

2. The method according to claim 1, characterized in that: The constructing feedback control according to the observed input parameter, the actual yaw rate and the ideal yaw rate comprises: Calculating a corrected yaw rate according to the observed input parameter, the actual yaw rate and the ideal yaw rate; Calculating a yaw angular velocity error between the actual yaw angular velocity and the corrected yaw angular velocity; Feedback control is established according to the swing angular velocity error.

3. The method according to claim 2, characterized in that The calculating the corrected yaw rate according to the observed input parameter, the actual yaw rate and the ideal yaw rate comprises: When the actual yaw angular velocity is not equal to the ideal yaw angular velocity, the hand-feel simulation actuator angle in the observed input parameter is not equal to the steering actuator angle in the observed input parameter within the first preset time, and the hand-feel simulation actuator speed in the observed input parameter is equal to the maximum characteristic speed of the hand-feel simulation actuator within the second preset time, the change rate of the hand-feel simulation actuator speed is greater than the target change rate, the change amplitude of the hand-feel simulation actuator angle is greater than the target change amplitude, or the vehicle speed is greater than the target vehicle speed, a correction coefficient is obtained according to the vehicle speed; Calculating an ideal correction factor based on the correction factor; The corrected yaw rate is calculated using a corrected yaw rate formula according to the ideal correction coefficient.

4. The method according to claim 1, characterized in that The compound control is: T=k*T FF +(1-k)*T PID Wherein, T is the composite control; T FF is the feedforward control; T PID is the feedback control; k is a positive integer.

5. The method according to claim 1, characterized in that The distributing the braking force according to the expected yaw moment comprises: When the observed input parameter exceeds the observed threshold within a third preset time, the step of distributing the braking force according to the expected yaw moment to obtain the expected braking force is performed.

6. The method according to claim 1, characterized in that After the desired braking force is obtained by distributing the braking force according to the desired yaw moment, the method further includes: Get the vehicle's current speed and wheel speed; Calculating a slip ratio according to the current vehicle speed and the current wheel speed of the vehicle; When the slip ratio is greater than a target slip ratio, the expected braking force is adjusted according to the target slip ratio until the slip ratio is equal to the target slip ratio.

7. The method according to claim 1, characterized in that The method further comprises: When the vehicle speed of the observed input parameter changes from not greater than the first preset speed to not less than the second preset speed or the vehicle speed of the observed input parameter changes from not less than the second preset speed to not greater than the first preset speed, activating the flag; The desired yaw moment is calculated by slowly switching from the feedforward control to the feedback control according to a fixed compensation using the flag bit or slowly switching from the feedback control to the feedforward control according to a fixed compensation using the flag bit.

8. A braking force distribution device, characterized in that: The device comprises: An acquisition preprocessing unit is used to acquire observation input parameters and actual yaw angular velocity, and preprocess the observation input parameters to obtain preprocessing parameters; A first calculation unit, configured to calculate an ideal yaw rate according to the preprocessing parameters; a constructing unit, configured to construct a feedback control according to the observed input parameter, the actual yaw rate and the ideal yaw rate, and to construct a feedforward control according to the observed input parameter; a second calculation unit, for calculating the desired yaw moment by using the feedforward control when the vehicle speed of the observed input parameter is less than or equal to the first preset speed; for calculating the desired yaw moment by using the feedback control when the vehicle speed of the observed input parameter is greater than or equal to the second preset speed; and for calculating the desired yaw moment by using the composite control of the feedback control and the feedforward control when the vehicle speed of the observed input parameter is greater than the first preset speed and less than the second preset speed, wherein the second preset speed is greater than the first preset speed; The braking force distribution unit is used to distribute the braking force according to the desired yaw moment to obtain the desired braking force.

9. A braking force distribution device, characterized in that: The device includes a memory and a processor, the memory is used to store a program or code, and the processor is used to run the program or code stored in the memory to implement the braking force distribution method according to any one of claims 1-7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores codes, and when the codes are executed, a device executing the codes implements the braking force distribution method according to any one of claims 1 to 7.

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