Vehicle path tracking prediction control method and system based on differential braking

Abstract

The invention relates to the technical field of vehicle motion control, in particular to a vehicle path tracking prediction control method, device and system based on differential braking. Aiming at a drive-by-wire hydraulic brake system equipped with a high-speed switch valve, the invention provides the differential brake-based vehicle path tracking prediction control method and system, so that the path tracking function can be realized through the design of the control scheme and the control method on the premise of not increasing the hardware cost of the brake system; a redundant path tracking control scheme is provided.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle motion control, and in particular to a vehicle path tracking prediction control method, device and system based on differential braking. Background Art

[0002] Path tracking control is a key technology for autonomous driving, and existing technical solutions mainly implement path tracking functions based on wire-controlled steering systems. In addition, in order to meet the functional safety requirements of high-level autonomous driving, that is, to ensure that the vehicle still has a certain path tracking capability after some components of the wire-controlled steering system fail, a technical solution for a redundant wire-controlled steering system is proposed. This technical solution redesigns the structure of the wire-controlled steering system, such as the use of redundant backup solutions such as dual steering motors and dual power supplies, to ensure that the vehicle still has path tracking capabilities after some components of the steering system fail. However, the above technical solution makes the mechanical structure and control method of the steering system very complicated, and greatly increases the cost of the system. Summary of the invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the problem of high cost of path tracking control in the prior art.

[0004] In order to solve the above technical problems, the present invention provides a vehicle path tracking prediction control method, comprising:

[0005] When the enable signal is monitored to be true, reference path information, vehicle status information and hydraulic brake system status information are obtained;

[0006] Calculating a vehicle lateral position deviation according to the reference path information, the vehicle state information and the hydraulic brake system state information, and calculating an equivalent expected yaw angle and an equivalent expected yaw rate according to the vehicle lateral position deviation;

[0007] Defining an effective control vector set of the inlet valve and the outlet valve group and an effective flow vector set of the corresponding wheel cylinder group according to the switch state of the solenoid valve, and establishing a dynamic equation of the wheel cylinder group flow vector to the vehicle yaw motion state according to the effective flow vector set of the wheel cylinder group;

[0008] Based on the dynamic equation, predicting the vehicle yaw motion state in the future control cycle according to the effective flow vector set of the brake wheel cylinder group;

[0009] A cost function is established according to the equivalent expected yaw angle and the equivalent expected yaw angular velocity, and the cost function is used as an optimization target to solve the optimal prediction value to achieve control of the vehicle yaw motion.

[0010] Preferably, before obtaining the reference path information, the vehicle status information and the hydraulic brake system status information, the step further includes:

[0011] Control the high voltage supply device to establish a stable high voltage source.

[0012] Preferably, the reference path information includes the global coordinates, heading angle and curvature of the reference path; the vehicle status information includes the global coordinates of the vehicle's center of mass, yaw angle, sideslip angle, longitudinal speed, lateral speed and yaw angular velocity; the hydraulic brake system status information includes the high-pressure supply device pressure, the low-pressure oil return device pressure and the four wheel cylinder pressures.

[0013] Preferably, the calculating the vehicle lateral position deviation according to the reference path information, the vehicle state information and the hydraulic brake system state information, and calculating the equivalent expected yaw angle and the equivalent expected yaw rate according to the vehicle lateral position deviation comprises:

[0014] Calculate the lateral position deviation of the vehicle according to the abscissa and ordinate of the vehicle center of mass position and the vehicle center of mass reference position in the global coordinate system, and the heading angle of the reference path;

[0015] Calculating an equivalent desired yaw angle according to the vehicle lateral position deviation, control parameters, a sideslip angle of the vehicle center of mass, and a heading angle of a reference path;

[0016] An equivalent expected yaw rate is calculated according to a first-order derivative of the equivalent expected yaw angle with respect to time.

[0017] Preferably, the effective control vector set of the inlet valve and the outlet valve group and the effective flow vector set of the corresponding wheel cylinder group are defined according to the switch state of the solenoid valve, and the dynamic equation of the wheel cylinder group flow vector to the vehicle yaw motion state is established according to the effective flow vector set of the wheel cylinder group, including:

[0018] Define the control vectors of the inlet valve and the outlet valve according to the switch state of the solenoid valve;

[0019] The switch states of the liquid inlet valve and the liquid outlet valve are controlled and combined to obtain an effective control vector set of the liquid inlet valve and the liquid outlet valve;

[0020] Calculate the effective flow vector of the brake wheel cylinder corresponding to the effective control vector of each inlet valve and outlet valve;

[0021] According to the effective control vector set of the inlet valve and the outlet valve and the effective flow vector set of the corresponding brake wheel cylinder, define the effective control vector set of the inlet valve and the outlet valve group and the effective flow vector set of the corresponding brake wheel cylinder group;

[0022] A dynamic equation from the flow vector of the wheel cylinder group to the yaw motion state of the vehicle is established according to the effective flow vector set of the wheel cylinder group.

[0023] Preferably, the prediction of all possible values ​​of the vehicle yaw motion state in the future control period based on the dynamic equation and the effective flow vector set of the wheel cylinder group includes:

[0024] Discretizing the dynamic equations;

[0025] real-time estimation of the lumped disturbance terms of the vehicle yaw motion equation and the wheel cylinder group pressure equation in the dynamic equation;

[0026] Based on the discretized dynamic equations and the lumped disturbance term, all possible values ​​of the vehicle yaw motion state in the future control period are predicted according to the effective flow vector set of the brake wheel cylinder group.

[0027] Preferably, establishing a cost function according to the equivalent expected yaw angle and the equivalent expected yaw angular velocity, and solving the optimal prediction value with the cost function as the optimization target to achieve control of the yaw motion of the vehicle includes:

[0028] Establishing a cost function according to the equivalent expected yaw angle and the equivalent expected yaw angular velocity;

[0029] Solving the optimization problem with the cost function as the optimization target to determine the optimal prediction value;

[0030] The optimal wheel cylinder group flow vector and the corresponding inlet valve and outlet valve group control vector are obtained according to the optimal prediction value to control the inlet valve and outlet valve group to perform opening or closing actions, thereby realizing the control of the vehicle yaw motion.

[0031] The present invention also provides a vehicle path tracking prediction control device, comprising:

[0032] A function trigger module, used for monitoring the enable signal of the differential path tracking function, and starting the differential path tracking control function when the enable signal is true, otherwise continuing to monitor;

[0033] A data processing module, used for obtaining reference path information, vehicle status information and hydraulic brake system status information;

[0034] an expected yaw motion calculation module, used to calculate a vehicle lateral position deviation according to the reference path information, vehicle state information and hydraulic brake system state information, and to calculate an equivalent expected yaw angle and an equivalent expected yaw angular velocity according to the vehicle lateral position deviation;

[0035] A yaw motion model building module, used to define an effective control vector set of the inlet valve and the outlet valve group and an effective flow vector set of the corresponding wheel cylinder group according to the switch state of the solenoid valve, and to establish a dynamic equation from the wheel cylinder group flow vector to the vehicle yaw motion state according to the effective flow vector set of the wheel cylinder group;

[0036] A yaw motion prediction module, used to predict the yaw motion state of the vehicle in a future control cycle based on the dynamic equation and the effective flow vector set of the brake wheel cylinder group;

[0037] The cost function evaluation module is used to establish a cost function according to the equivalent expected yaw angle and the equivalent expected yaw angular velocity, and to solve the optimal prediction value with the cost function as the optimization target to realize the control of the vehicle yaw motion.

[0038] The present invention also provides a vehicle path tracking prediction control system, comprising:

[0039] High pressure supply device;

[0040] A low-pressure oil return device connected to the high-pressure supply device;

[0041] A plurality of brake units, each of which is connected to the low-pressure oil return device and the high-pressure oil supply device, and each of which comprises a pressure sensor, a liquid inlet valve, a liquid outlet valve and a brake wheel cylinder;

[0042] A hydraulic control unit is connected to the high-pressure supply device, the low-pressure oil return device and the plurality of brake units, and includes the vehicle path tracking prediction control device as described above, and is used to control the yaw motion of the vehicle.

[0043] Preferably, the high-pressure supply device includes a high-pressure accumulator type high-pressure supply device and an electric-powered master cylinder type high-pressure supply device.

[0044] The above technical solution of the present invention has the following advantages compared with the prior art:

[0045] The present invention is aimed at a wire-controlled hydraulic brake system equipped with a high-speed switching valve, and proposes a vehicle path tracking prediction control method and system based on differential braking. The method can realize the path tracking function through the design of the control scheme and the control method without increasing the hardware cost of the brake system, and provide a redundant path tracking control scheme. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0047] Figure 1 It is a flow chart of the implementation of a vehicle path tracking prediction control method provided by the present invention;

[0048] Figure 2 It is a structural schematic diagram of a vehicle path tracking prediction control device provided by the present invention;

[0049] Figure 3 It is a structural schematic diagram of a vehicle path tracking prediction control system provided by the present invention. DETAILED DESCRIPTION

[0050] The core of the present invention is to provide a vehicle path tracking prediction control method, device, equipment and computer storage medium, which effectively reduces system costs.

[0051] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0052] At present, the wire-controlled hydraulic brake system generally has the ability to independently adjust the brake pressure of four wheels. Therefore, by increasing the brake pressure of one wheel relative to the other wheel to generate a yaw moment, the yaw motion state of the vehicle can be changed. Therefore, the wire-controlled hydraulic brake system has the potential to achieve path tracking control. At present, high-speed switching solenoid valves are widely used in wire-controlled hydraulic brake systems due to their advantages such as simple structure and low cost, and are used to control the brake pressure of wheel cylinders. For the wire-controlled hydraulic brake system equipped with a high-speed switching valve, the present invention proposes a vehicle path tracking prediction control method based on differential braking.

[0053] Please refer to Figure 1 , Figure 1 This is a flow chart of the implementation of a vehicle path tracking prediction control method provided by the present invention; the specific operation steps are as follows:

[0054] S101: when the enable signal is monitored to be true, obtaining reference path information, vehicle status information and hydraulic brake system status information;

[0055] S102: calculating a vehicle lateral position deviation according to the reference path information, the vehicle state information and the hydraulic brake system state information, and calculating an equivalent expected yaw angle and an equivalent expected yaw rate according to the vehicle lateral position deviation;

[0056] S103: defining an effective control vector set of the inlet valve and the outlet valve group and an effective flow vector set of the corresponding wheel cylinder group according to the switch state of the solenoid valve, and establishing a dynamic equation of the wheel cylinder group flow vector to the vehicle yaw motion state according to the effective flow vector set of the wheel cylinder group;

[0057] S104: Based on the dynamic equation, predict the vehicle yaw motion state in the future control cycle according to the effective flow vector set of the brake wheel cylinder group;

[0058] S105: Establishing a cost function according to the equivalent expected yaw angle and the equivalent expected yaw angular velocity, and solving the optimal prediction value with the cost function as the optimization target to achieve control of the vehicle yaw motion.

[0059] Based on the above embodiments, this embodiment describes step S101 in detail:

[0060] Monitor the enable signal of the differential path tracking function. If the enable signal is true, start the differential path tracking control function, otherwise continue monitoring;

[0061] When the enable signal is monitored to be true, the high-pressure supply device is controlled to establish a stable high-pressure source, and reference path information, vehicle status information and hydraulic brake system status information are obtained; the reference path information includes the global coordinates, heading angle and curvature of the reference path; the vehicle status information includes the global coordinates of the vehicle's center of mass, yaw angle, sideslip angle, longitudinal speed, lateral speed and yaw angular velocity; the hydraulic brake system status information includes the pressure of the high-pressure supply device, the pressure of the low-pressure oil return device and the pressures of the four wheel cylinders.

[0062] Based on the above embodiments, this embodiment describes step S102 in detail:

[0063] We calculate the vehicle lateral position deviation based on the horizontal and vertical coordinates of the vehicle center of mass position and the vehicle center of mass reference position in the global coordinate system, and the heading angle of the reference path. The vehicle lateral position deviation is defined as:

[0064] z e =(r h -r ref ) T n ref

[0065] Where z e represents the vehicle lateral position error, r h =[x h y h ] T , x h and h are the horizontal and vertical coordinates of the vehicle's center of mass in the global coordinate system, r ref =[x ref y ref ] T , x ref and ref are the horizontal and vertical coordinates of the vehicle's center of mass reference position in the global coordinate system, nref =[-sinθ ref cosθ ref ] T , where θ ref is the reference heading angle.

[0066] Then, the equivalent desired yaw angle is calculated according to the vehicle lateral position deviation, control parameters, the sideslip angle of the vehicle center of mass and the heading angle of the reference path. The equivalent desired yaw angle is defined as:

[0067]

[0068] In the formula is the equivalent desired yaw angle, c0 and c1 are control parameters, 0 <c0<π,c1> 0, β is the vehicle's sideslip angle.

[0069] Finally, the equivalent expected yaw rate is calculated according to the first-order derivative of the equivalent expected yaw angle with respect to time. The equivalent expected yaw rate is defined as:

[0070]

[0071] Where r des represents the equivalent desired yaw rate, represents the first-order derivative of the equivalent desired yaw angle with respect to time.

[0072] Based on the above embodiments, this embodiment describes step S103 in detail:

[0073] Define the control vector of the inlet valve and outlet valve according to the switch state of the solenoid valve:

[0074] Define the switch state of the solenoid valve as:

[0075]

[0076] Where S vi Indicates the switching state of the solenoid valve, the subscripts v=I, O respectively represent the liquid inlet valve and the liquid outlet valve, and the subscripts i=1,2,3,4 respectively represent the first braking unit, the second braking unit, the third braking unit and the fourth braking unit.

[0077] According to the switch state of the solenoid valve, the control vector of the inlet valve and the outlet valve is defined as:

[0078] S i =(S Ii S Oi ) T

[0079] Where S i Represents the control vector of the inlet valve and the outlet valve.

[0080] The switch states of the inlet valve and the outlet valve are controlled and combined to obtain the effective control vector set of the inlet valve and the outlet valve:

[0081] Consider three control combinations: (1) the inlet valve and the outlet valve are closed at the same time; (2) the inlet valve is open and the outlet valve is closed; (3) the inlet valve is closed and the outlet valve is open. The effective control vector set of the inlet valve and the outlet valve is defined as

[0082]

[0083] Where S i is the effective control vector set of the inlet valve and the outlet valve, where The superscripts 0, 1, and 2 correspond to the above three control combinations, so S i ∈S i .

[0084] Calculate the effective flow vector of the brake wheel cylinder corresponding to the effective control vector of each inlet valve and outlet valve:

[0085] Use Q i represents the flow rate of the brake wheel cylinder, and all possible values ​​are calculated as follows

[0086]

[0087] In the formula and Corresponding to and The wheel cylinder flow rate, C d is the solenoid valve flow coefficient, A v is the cross-sectional area of ​​the solenoid valve port, ρ is the brake fluid density, P s is the pressure of the high-pressure supply device, P0 is the pressure of the low-pressure oil return device, P wi is the wheel cylinder pressure.

[0088] The effective flow set of the brake wheel cylinder is defined as

[0089]

[0090] In the formula represents the effective flow set of the brake wheel cylinder, then

[0091] According to the effective control vector set of the inlet valve and the outlet valve and the effective flow vector set of the corresponding brake wheel cylinder, define the effective control vector set of the inlet valve and the outlet valve group and the effective flow vector set of the corresponding brake wheel cylinder group:

[0092] Define the control vector of the inlet valve and outlet valve group as

[0093]

[0094] Where S is the control vector of the inlet valve and the outlet valve group, then the effective control vector set of the inlet valve and the outlet valve group can be expressed as

[0095]

[0096] Where S represents the effective control vector set of the inlet valve and outlet valve group.

[0097] Accordingly, the flow vector of the brake wheel cylinder group is defined as

[0098] Q=(Q1 Q2 Q3 Q4) T

[0099] Where Q represents the flow vector of the brake wheel cylinder group, then the effective flow vector set of the brake wheel cylinder group can be expressed as

[0100]

[0101] In the formula Represents the effective flow vector set of the brake wheel cylinder group.

[0102] The dynamic equation of the flow vector of the wheel cylinder group to the yaw motion state of the vehicle is established according to the flow vector set of the wheel cylinder group:

[0103]

[0104] In the formula, represents the vehicle yaw angle; x2=r represents the vehicle yaw angular velocity; x3=(P w1 P w2 P w3 P w4 ) T is the wheel cylinder group pressure vector, P w1 ,P w2 ,P w3 ,P w4 are the pressures of the first, second, third and fourth wheel cylinders respectively; U=Q is the flow vector of the brake wheel cylinder group; is the yaw motion input matrix, where c is the vehicle wheelbase, I z is the vehicle yaw moment of inertia, R w is the wheel radius, K b1 ,K b2 ,K b3 ,K b4 are gain coefficients from the wheel cylinder pressure to the braking torque of the first, second, third and fourth brake units respectively; is the wheel cylinder group input matrix, where Vw1 ,V w2 ,V w3 ,V w4 are the initial volumes of the first, second, third and fourth wheel cylinders, β e is the brake fluid bulk modulus; D r is the lumped perturbation of the yaw motion equation, D w =(D w1 D w2 D w3 D w4 ) T is the lumped disturbance of the wheel cylinder group pressure equation, where D w1 ,D w2 ,D w3 ,D w4 They are the lumped disturbances of the wheel cylinder pressure equations of the first, second, third and fourth brake units respectively.

[0105] Based on the above embodiments, this embodiment describes step S104 in detail:

[0106] Discretize the dynamic equation:

[0107]

[0108] Where k represents the kth sampling period, T s Indicates the sampling period.

[0109] Real-time estimation of the lumped disturbance terms of the vehicle yaw motion equation and the wheel cylinder group pressure equation in the dynamic equation:

[0110]

[0111] Where z 11 (k),z 12 (k),z 13 (k) are x1(k), x2(k), D r The estimated value of (k), L 11 ,L 12 ,L 13 is the observer gain coefficient; z 21 (k),z 22 (k) are x3(k), D w The estimated value of (k), L 21 ,L 22 is the observer gain matrix.

[0112] Based on the discretized dynamic equation and the lumped disturbance term, all possible values ​​of the vehicle yaw motion state in the future control period are predicted according to the effective flow vector set of the brake wheel cylinder group:

[0113] The one-step prediction equation is:

[0114]

[0115] Where U(k) traverses Each element in .

[0116] Furthermore, the two-step prediction equation is

[0117]

[0118] Furthermore, the three-step prediction equation is

[0119]

[0120] Based on the above embodiments, this embodiment describes step S105 in detail:

[0121] Establishing a cost function according to the equivalent desired yaw angle and the equivalent desired yaw angular velocity:

[0122] J=w1J1+w2J2+w3J3

[0123] Where w1, w2, w3 are weight coefficients, J1, J2, J3 are calculated using the following formula:

[0124]

[0125]

[0126] Where K P1 ,K I1 ,K D1 ,K P2 ,K I2 ,K D2 is the control parameter, 14=(1111) T is a constant array, is the equivalent desired yaw angle, is the equivalent desired yaw rate.

[0127] Solve the optimization problem with the cost function as the optimization target and determine the optimal prediction value:

[0128] min J

[0129] st

[0130] Obtaining an optimal wheel cylinder group flow vector and a corresponding inlet valve and outlet valve group control vector according to the optimal prediction value, so as to control the inlet valve and outlet valve group to perform an opening or closing action, thereby achieving control of the vehicle yaw motion.

[0131] The present invention realizes the path tracking function through the design of control scheme and control method without increasing the hardware cost of the braking system, and provides a redundant path tracking prediction control method and system based on differential braking. According to the discrete working characteristics of the fully open and fully closed electromagnetic valves, the effective control vector set of the inlet valve and the outlet valve group and the corresponding effective flow vector set of the brake wheel cylinder group are defined, and the dynamic equation from the flow vector of the brake wheel cylinder group to the yaw motion state is established, and the relationship between the switch state of the electromagnetic valve and the yaw motion state of the vehicle is quantitatively characterized. The optimal control vector of the inlet valve and the outlet valve group is directly obtained by evaluating all the predicted values, which changes the original cascade differential motion control scheme, cancels the pulse width modulation device of the pressure control loop, simplifies the control system structure, and reduces the complexity of the control algorithm.

[0132] Please refer to Figure 2 , Figure 2 A structural block diagram of a vehicle path tracking prediction control device provided by an embodiment of the present invention; the specific device may include:

[0133] A function trigger module, used for monitoring the enable signal of the differential path tracking function, and starting the differential path tracking control function when the enable signal is true, otherwise continuing to monitor;

[0134] A data processing module, used for obtaining reference path information, vehicle status information and hydraulic brake system status information;

[0135] an expected yaw motion calculation module, used to calculate a vehicle lateral position deviation according to the reference path information, vehicle state information and hydraulic brake system state information, and to calculate an equivalent expected yaw angle and an equivalent expected yaw angular velocity according to the vehicle lateral position deviation;

[0136] A yaw motion model building module, used to define an effective control vector set of the inlet valve and the outlet valve group and an effective flow vector set of the corresponding wheel cylinder group according to the switch state of the solenoid valve, and to establish a dynamic equation from the wheel cylinder group flow vector to the vehicle yaw motion state according to the effective flow vector set of the wheel cylinder group;

[0137] A yaw motion prediction module, used to predict the yaw motion state of the vehicle in a future control cycle based on the dynamic equation and the effective flow vector set of the brake wheel cylinder group;

[0138] The cost function evaluation module is used to establish a cost function according to the equivalent expected yaw angle and the equivalent expected yaw angular velocity, and to solve the optimal prediction value with the cost function as the optimization target to realize the control of the vehicle yaw motion.

[0139] Based on the above embodiments, the yaw motion prediction module is also connected to a first disturbance observation module and a second disturbance observation module, the first disturbance observation module is used to estimate the lumped disturbance of the yaw motion equation in the dynamic equation according to the deviation between the yaw angle measurement value and the observation value, and the second disturbance observation module is used to estimate the lumped disturbance of the brake wheel cylinder group pressure equation in the dynamic equation according to the deviation between the measurement value and the observation value of the current brake wheel cylinder group pressure.

[0140] The vehicle path tracking prediction control device of this embodiment is used to implement the aforementioned vehicle path tracking prediction control method. Therefore, the specific implementation method of the vehicle path tracking prediction control device can be seen in the embodiment part of the vehicle path tracking prediction control method above, for example, the function trigger module, the data processing module, the expected yaw motion calculation module, the yaw motion model establishment module, the yaw motion prediction module, and the cost function evaluation module are used to implement steps S101-S105 in the above-mentioned vehicle path tracking prediction control method. Therefore, its specific implementation method can refer to the description of the corresponding various parts of the embodiment, which will not be repeated here.

[0141] like Figure 3 As shown, the present invention also provides a vehicle path tracking prediction control system, comprising:

[0142] A high-voltage supply device, including but not limited to a high-voltage accumulator type high-voltage supply device and an electric-assisted master cylinder type high-voltage supply device, for providing a stable high-voltage source;

[0143] A low-pressure oil return device connected to the high-pressure supply device;

[0144] A plurality of brake units, each of which is connected to the low-pressure oil return device and the high-pressure oil supply device, and each of which comprises a pressure sensor, a liquid inlet valve, a liquid outlet valve and a brake wheel cylinder;

[0145] A hydraulic control unit is connected to the high-pressure supply device, the low-pressure oil return device and the plurality of brake units, and includes the vehicle path tracking prediction control device as described above, and is used to control the yaw motion of the vehicle.

[0146] Based on the above embodiments, the multiple brake units include a first brake unit 1, a second brake unit 2, a third brake unit 3, and a fourth brake unit 4. The first brake unit 1 includes a first brake wheel cylinder 11, a first liquid inlet valve 12, a first liquid outlet valve 13 and a first pressure sensor 14; the second brake unit 2 includes a second brake wheel cylinder 21, a second liquid inlet valve 22, a second liquid outlet valve 23 and a second pressure sensor 24; the third brake unit 3 includes a third brake wheel cylinder 31, a third liquid inlet valve 32, a third liquid outlet valve 33 and a third pressure sensor 34; the fourth brake unit 4 includes a fourth brake wheel cylinder 41, a fourth liquid inlet valve 42, a fourth liquid outlet valve 43 and a fourth pressure sensor 44. The first inlet valve 12 is used to control the flow of brake fluid flowing into the first brake wheel cylinder 11, and the first outlet valve 13 is used to control the flow of brake fluid flowing out of the first brake wheel cylinder 11, thereby realizing the control of the pressure of the first brake wheel cylinder 11; the second inlet valve 22 is used to control the flow of brake fluid flowing into the second brake wheel cylinder 21, and the second outlet valve 23 is used to control the flow of brake fluid flowing out of the second brake wheel cylinder 21, thereby realizing the control of the pressure of the second brake wheel cylinder 21; the third inlet valve 32 is used to control the flow of brake fluid flowing into the third brake wheel cylinder 31, and the third outlet valve 33 is used to control the flow of brake fluid flowing out of the third brake wheel cylinder 31, thereby realizing the control of the pressure of the third brake wheel cylinder 31; the fourth inlet valve 42 is used to control the flow of brake fluid flowing into the fourth brake wheel cylinder 41, and the fourth outlet valve 43 is used to control the flow of brake fluid flowing out of the fourth brake wheel cylinder 41, thereby realizing the control of the pressure of the fourth brake wheel cylinder 41.

[0147] Based on the above embodiment, the vehicle path tracking prediction control system further includes a fifth pressure sensor 5 for measuring the pressure of the high-pressure supply device 6 .

[0148] Based on the above embodiment, the low-pressure oil return device 7 recovers the brake fluid flowing out of the first wheel-brake cylinder 11 , the second wheel-brake cylinder 21 , the third wheel-brake cylinder 31 , and the fourth wheel-brake cylinder 41 .

[0149] Based on the above embodiments, the hydraulic control unit 8 collects signals from the first pressure sensor 14, the second pressure sensor 24, the third pressure sensor 34, the fourth pressure sensor 44, and the fifth pressure sensor 5, runs the proposed path tracking control algorithm, and controls the switching states of the first inlet valve 12, the first outlet valve 13, the second inlet valve 22, the second outlet valve 23, the third inlet valve 32, the third outlet valve 33, the fourth inlet valve 42, and the fourth outlet valve 43.

[0150] Obviously, the above embodiments are merely examples for the purpose of clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A vehicle path tracking prediction control method, characterized in that: include: When the enable signal is monitored to be true, reference path information, vehicle status information and hydraulic brake system status information are obtained; Calculating a vehicle lateral position deviation according to the reference path information, the vehicle state information and the hydraulic brake system state information, and calculating an equivalent expected yaw angle and an equivalent expected yaw rate according to the vehicle lateral position deviation; Defining an effective control vector set of the inlet valve and the outlet valve group and an effective flow vector set of the corresponding wheel cylinder group according to the switch state of the solenoid valve, and establishing a dynamic equation of the wheel cylinder group flow vector to the vehicle yaw motion state according to the effective flow vector set of the wheel cylinder group; Based on the dynamic equation, predicting the vehicle yaw motion state in the future control cycle according to the effective flow vector set of the brake wheel cylinder group; A cost function is established according to the equivalent expected yaw angle and the equivalent expected yaw angular velocity, and the cost function is used as an optimization target to solve the optimal prediction value to achieve control of the vehicle yaw motion.

2. The vehicle path tracking prediction control method according to claim 1, characterized in that: The obtaining of reference path information, vehicle status information and hydraulic brake system status information also includes: Control the high voltage supply device to establish a stable high voltage source.

3. The vehicle path tracking prediction control method according to claim 1, characterized in that: The reference path information includes the global coordinates, heading angle and curvature of the reference path; the vehicle status information includes the global coordinates of the vehicle's center of mass, yaw angle, sideslip angle, longitudinal speed, lateral speed and yaw angular velocity; the hydraulic brake system status information includes the high-pressure supply device pressure, the low-pressure oil return device pressure and the four wheel cylinder pressures.

4. The vehicle path tracking prediction control method according to claim 3, characterized in that: The calculating the vehicle lateral position deviation according to the reference path information, the vehicle state information and the hydraulic brake system state information, and calculating the equivalent expected yaw angle and the equivalent expected yaw rate according to the vehicle lateral position deviation comprises: Calculate the lateral position deviation of the vehicle according to the abscissa and ordinate of the vehicle center of mass position and the vehicle center of mass reference position in the global coordinate system, and the heading angle of the reference path; Calculating an equivalent desired yaw angle according to the vehicle lateral position deviation, control parameters, a sideslip angle of the vehicle center of mass, and a heading angle of a reference path; An equivalent expected yaw rate is calculated according to a first-order derivative of the equivalent expected yaw angle with respect to time.

5. The vehicle path tracking prediction control method according to claim 1, characterized in that: The effective control vector set of the inlet valve and the outlet valve group and the effective flow vector set of the corresponding wheel cylinder group are defined according to the switch state of the solenoid valve, and the dynamic equation of the wheel cylinder group flow vector to the vehicle yaw motion state is established according to the effective flow vector set of the wheel cylinder group, including: Define the control vectors of the inlet valve and the outlet valve according to the switch state of the solenoid valve; The switch states of the liquid inlet valve and the liquid outlet valve are controlled and combined to obtain an effective control vector set of the liquid inlet valve and the liquid outlet valve; Calculate the effective flow vector of the brake wheel cylinder corresponding to the effective control vector of each inlet valve and outlet valve; According to the effective control vector set of the inlet valve and the outlet valve and the effective flow vector set of the corresponding brake wheel cylinder, define the effective control vector set of the inlet valve and the outlet valve group and the effective flow vector set of the corresponding brake wheel cylinder group; A dynamic equation from the flow vector of the wheel cylinder group to the yaw motion state of the vehicle is established according to the effective flow vector set of the wheel cylinder group.

6. The vehicle path tracking prediction control method according to claim 5, characterized in that: Based on the dynamic equation, all possible values ​​of the vehicle yaw motion state in the future control period are predicted according to the effective flow vector set of the brake wheel cylinder group, including: Discretizing the dynamic equations; real-time estimation of the lumped disturbance terms of the vehicle yaw motion equation and the wheel cylinder group pressure equation in the dynamic equation; Based on the discretized dynamic equations and the lumped disturbance term, all possible values ​​of the vehicle yaw motion state in the future control period are predicted according to the effective flow vector set of the brake wheel cylinder group.

7. The vehicle path tracking prediction control method according to claim 1, characterized in that: The step of establishing a cost function according to the equivalent expected yaw angle and the equivalent expected yaw angular velocity, and solving an optimal prediction value with the cost function as an optimization target to achieve control of the yaw motion of the vehicle includes: Establishing a cost function according to the equivalent expected yaw angle and the equivalent expected yaw angular velocity; Solving the optimization problem with the cost function as the optimization target to determine the optimal prediction value; The optimal wheel cylinder group flow vector and the corresponding inlet valve and outlet valve group control vector are obtained according to the optimal prediction value to control the inlet valve and outlet valve group to perform opening or closing actions, thereby realizing the control of the vehicle yaw motion.

8. A vehicle path tracking prediction control device, characterized in that: include: A function trigger module, used for monitoring the enable signal of the differential path tracking function, and starting the differential path tracking control function when the enable signal is true, otherwise continuing to monitor; A data processing module, used for obtaining reference path information, vehicle status information and hydraulic brake system status information; an expected yaw motion calculation module, used to calculate a vehicle lateral position deviation according to the reference path information, vehicle state information and hydraulic brake system state information, and to calculate an equivalent expected yaw angle and an equivalent expected yaw angular velocity according to the vehicle lateral position deviation; A yaw motion model building module, used to define an effective control vector set of the inlet valve and the outlet valve group and an effective flow vector set of the corresponding wheel cylinder group according to the switch state of the solenoid valve, and to establish a dynamic equation from the wheel cylinder group flow vector to the vehicle yaw motion state according to the effective flow vector set of the wheel cylinder group; A yaw motion prediction module, used to predict the yaw motion state of the vehicle in a future control cycle based on the dynamic equation and the effective flow vector set of the brake wheel cylinder group; The cost function evaluation module is used to establish a cost function according to the equivalent expected yaw angle and the equivalent expected yaw angular velocity, and to solve the optimal prediction value with the cost function as the optimization target to realize the control of the vehicle yaw motion.

9. A vehicle path tracking prediction control system, characterized in that: include: High pressure supply device; A low-pressure oil return device connected to the high-pressure supply device; A plurality of brake units, each of which is connected to the low-pressure oil return device and the high-pressure oil supply device, and each of which comprises a pressure sensor, a liquid inlet valve, a liquid outlet valve and a brake wheel cylinder; A hydraulic control unit, connected to the high-pressure supply device, the low-pressure oil return device and the plurality of brake units, comprises the vehicle path tracking prediction control device as claimed in claim 8, and is used to control the yaw motion of the vehicle.

10. The vehicle path tracking prediction control system according to claim 9, characterized in that: The high-pressure supply device includes a high-pressure accumulator type high-pressure supply device and an electric-assisted master cylinder type high-pressure supply device.

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