A vehicle path tracking predictive control method and system based on differential braking

Abstract

The present application relates to the technical field of vehicle motion control, in particular to a vehicle path tracking predictive control method, device and system based on differential braking. The present application proposes a vehicle path tracking predictive control method and system based on differential braking for a hydraulic brake-by-wire system equipped with high-speed on-off valves. The method and system can realize path tracking function and provide a redundant path tracking control scheme without increasing the hardware cost of the brake system through the design of control scheme and control method.

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 steer-by-wire systems. In addition, 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 the failure of some components of the steer-by-wire system, a technical solution for a redundant steer-by-wire system has been proposed. This technical solution redesigns the structure of the steer-by-wire system, such as adopting redundant backup solutions such as dual steering motors and dual power supplies, to ensure that the vehicle still has path tracking capabilities after the failure of some components of the steering system. 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 path tracking control cost in the prior art.

[0004] 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 based on 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 based on the vehicle lateral position deviation;

[0007] Defining a set of effective control vectors for the inlet and outlet valves and a set of effective flow vectors for the corresponding wheel-cylinder groups based on the on / off states of the solenoid valves, and establishing a dynamic equation for the wheel-cylinder group flow vectors to the vehicle's yaw motion state based on the effective flow vectors for the wheel-cylinder groups;

[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 desired yaw angle and the equivalent desired 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 method 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 return oil 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 includes:

[0014] 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;

[0015] Calculating an equivalent desired yaw angle based on 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 desired yaw rate is calculated according to a first-order derivative of the equivalent desired yaw angle with respect to time.

[0017] Preferably, defining the effective control vector set of the inlet valve and the outlet valve group and the corresponding effective flow vector set of the wheel cylinder group according to the switching state of the solenoid valve, and establishing the 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 includes:

[0018] Define the control vectors of the inlet valve and the outlet valve according to the switching 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, 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 are defined;

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

[0023] Preferably, the step of predicting all possible values of the vehicle yaw motion state in the future control period according to the set of effective flow rate vectors of the brake wheel cylinder group based on the kinetic equation comprises:

[0024] discretizing the kinetic equation;

[0025] estimating in real time the lumped disturbance terms of the vehicle yaw motion equation and the brake wheel cylinder group pressure equation in the kinetic equation;

[0026] predicting all possible values of the vehicle yaw motion state in the future control period according to the set of effective flow rate vectors of the brake wheel cylinder group based on the discretized kinetic equation and the lumped disturbance terms.

[0027] Preferably, the step of establishing a cost function according to the equivalent desired yaw angle and the equivalent desired yaw angular velocity and solving the optimal prediction value as an optimization objective of the cost function to realize the control of the vehicle yaw motion comprises:

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

[0029] solving an optimization problem as an optimization objective of the cost function to determine the optimal prediction value;

[0030] obtaining an optimal brake wheel cylinder group flow rate vector and a corresponding control vector of the inlet valve and outlet valve group according to the optimal prediction value to control the inlet valve and outlet valve group to perform the opening or closing action, thereby realizing the control of the vehicle yaw motion.

[0031] The application further provides a vehicle path tracking prediction control device, comprising:

[0032] a function triggering module configured to monitor an enabling signal of the differential path tracking function, and start the differential path tracking control function when the enabling signal is true, or continue monitoring otherwise;

[0033] a data processing module configured to obtain reference path information, vehicle state information and hydraulic braking system state information;

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

[0035] a yaw motion model establishing module configured to define a set of effective control vectors of the inlet valve and outlet valve group and a set of effective flow rate vectors of the brake wheel cylinder group according to the on-off state of the electromagnetic valve, and establish a kinetic equation of the brake wheel cylinder group flow rate vector to the vehicle yaw motion state according to the set of effective flow rate vectors of the brake wheel cylinder group.

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

[0037] The cost function evaluation module is used to establish a cost function based on 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 achieve 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 includes a pressure sensor, a liquid inlet valve, a liquid outlet valve, and a brake wheel cylinder;

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

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

[0044] The above technical solution of the present invention has the following advantages over 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. Without increasing the hardware cost of the brake system, the path tracking function can be realized through the design of the control scheme and control method, providing 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 based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

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

[0048] Figure 2 This is a structural 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 present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0052] Currently, wire-controlled hydraulic brake systems generally have the ability to independently adjust brake pressure on all four wheels. This allows the vehicle's yaw motion to be altered by increasing the brake pressure on one wheel relative to the other, generating a yaw moment. Therefore, wire-controlled hydraulic brake systems have the potential to implement path-following control. High-speed switching solenoid valves, due to their simple structure and low cost, are widely used in wire-controlled hydraulic brake systems to control wheel cylinder brake pressure. This paper proposes a vehicle path-following predictive control method based on differential braking for wire-controlled hydraulic brake systems equipped with high-speed switching valves.

[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 based on 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 based on the vehicle lateral position deviation;

[0056] S103: Defining a set of effective control vectors for the inlet and outlet valves and a set of effective flow vectors for the corresponding wheel-cylinder groups based on the on / off states of the solenoid valves, and establishing a dynamic equation for the wheel-cylinder group flow vectors to the vehicle's yaw motion state based on the effective flow vectors for the wheel-cylinder groups.

[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 wheel cylinder group;

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

[0059] Based on the above embodiment, 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 detected as true, the system controls the high-pressure supply device to establish a stable high-pressure source and obtains reference path information, vehicle status information, and hydraulic brake system status information. 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 velocity, lateral velocity, and yaw angular velocity; and the hydraulic brake system status information includes the pressure of the high-pressure supply device, the pressure of the low-pressure return device, and the pressures of the four wheel cylinders.

[0062] Based on the above embodiment, 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, as well as 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 y h are the horizontal and vertical coordinates of the vehicle's center of mass position in the global coordinate system, r ref =[x ref y ref ] T , x ref and y 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, an equivalent desired yaw angle is calculated based on 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 at the center of mass.

[0069] Finally, the equivalent desired yaw rate is calculated based on the first-order derivative of the equivalent desired yaw angle with respect to time. The equivalent desired 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 embodiment, this embodiment describes step S103 in detail:

[0073] Define the control vectors of the inlet and outlet valves according to the switching 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, subscripts v=I, O represent the liquid inlet valve and the liquid outlet valve respectively, and subscripts i=1, 2, 3, 4 represent the first brake unit, the second brake unit, the third brake unit and the fourth brake unit respectively.

[0077] According to the switching state of the solenoid valve, the control vectors of the inlet valve and the outlet valve are 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. Then 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 three control combinations mentioned above, 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 It 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] Based on the effective control vector set of the inlet valve and 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 outlet valve group and the effective flow vector set of the corresponding brake wheel cylinder group:

[0092] The control vector of the inlet valve and outlet valve group is defined as

[0093]

[0094] Where S is the control vector of the inlet valve and outlet valve group, then the effective control vector set of the inlet valve and 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, and 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] Based on the flow vector set of the wheel cylinder group, a dynamic equation is established to convert the flow vector of the wheel cylinder group to the vehicle yaw motion state:

[0103]

[0104] Where, 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's yaw moment of inertia, R w is the wheel radius, K b1 ,K b2 ,K b3 ,K b4 are the gain coefficients from the wheel cylinder pressure to the braking torque of the first, second, third and fourth brake units respectively; is the input matrix of the brake wheel cylinder group, where Vw1 w2 w3 w4 are the initial volumes of the first, second, third, fourth wheel cylinders, respectively e is the brake fluid bulk modulus; D r is the lumped disturbance of the yaw motion equation, D w = (D w1 D w2 D w3 D w4 ) T is the lumped disturbance of the brake wheel cylinder group pressure equation, where D w1 , D w2 , D w3 , D w4 are the lumped disturbances of the first, second, third, fourth brake unit wheel cylinder pressure equations, respectively.

[0105] Based on the above embodiment, the present embodiment explains step S104 in detail:

[0106] • Discretize the dynamic equations:

[0107]

[0108] where k represents the k-th sampling period, T s represents the sampling period.

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

[0110]

[0111] where z 11 (k), z 12 (k), z 13 (k) are the estimated values of x1(k), x2(k), D r (k), respectively, L 11 , L 12 , L 13 are the observer gain coefficients; z 21 (k), z 22 (k) are the estimated values of x3(k), D w (k), respectively, L 21 , L 22 are the observer gain matrices.

[0112] • Based on the discretized dynamic equations and the lumped disturbance terms, predict all possible values of the vehicle yaw motion state in the future control period according to the set of brake wheel cylinder group effective flow vectors: ​​​

[0113] Among them, 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 embodiment, this embodiment describes step S105 in detail:

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

[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 objective and determine the optimal prediction value:

[0128] min J

[0129] st

[0130] Obtaining the optimal wheel-cylinder group flow vector and corresponding inlet and outlet valve group control vectors based on the optimal predicted value to control the inlet and outlet valve groups to open or close, thereby controlling the vehicle's 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 solenoid valve, 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. The relationship between the switching state of the solenoid valve and the yaw motion state of the vehicle is quantitatively characterized, and the optimal control vector of the inlet valve and the outlet valve group is directly obtained by evaluating all predicted values. The original cascade differential motion control scheme is changed, the pulse width modulation device of the pressure control loop is eliminated, the control system structure is simplified, and the complexity of the control algorithm is reduced.

[0132] Please refer to Figure 2 , Figure 2 This is 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 is used to monitor the enable signal of the differential path tracking function, and when the enable signal is true, start the differential path tracking control function, otherwise continue monitoring;

[0134] A data processing module is used to obtain reference path information, vehicle status information and hydraulic brake system status information;

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

[0136] a yaw motion model establishment module, configured to define a set of effective control vectors for the inlet and outlet valves and the corresponding effective flow vectors for the wheel cylinder group based on the on / off states of the solenoid valves, and to establish a dynamic equation for the wheel cylinder group flow vector to the vehicle's yaw motion state based on the effective flow vectors for the wheel cylinder group;

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

[0138] The cost function evaluation module is used to establish a cost function based on 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 achieve control of the vehicle yaw motion.

[0139] Based on the above embodiment, 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 based on the deviation between the yaw angle measurement value and the observation value. The second disturbance observation module is used to estimate the lumped disturbance of the brake wheel cylinder group pressure equation in the dynamic equation based on 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 methods of the vehicle path tracking prediction control device can be found 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 aforementioned vehicle path tracking prediction control method. Therefore, its specific implementation methods can refer to the descriptions of the corresponding embodiments of each part and 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-powered 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 includes a pressure sensor, a liquid inlet valve, a liquid outlet valve, and a brake wheel cylinder;

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

[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 brake fluid flow rate flowing into the first brake wheel cylinder 11, and the first outlet valve 13 is used to control the brake fluid flow rate flowing out of the first brake wheel cylinder 11, thereby achieving control of the pressure of the first brake wheel cylinder 11; the second inlet valve 22 is used to control the brake fluid flow rate flowing into the second brake wheel cylinder 21, and the second outlet valve 23 is used to control the brake fluid flow rate flowing out of the second brake wheel cylinder 21, thereby achieving control of the pressure of the second brake wheel cylinder 21; the third inlet valve 32 is used to control the brake fluid flow rate flowing into the third brake wheel cylinder 31, and the third outlet valve 33 is used to control the brake fluid flow rate flowing out of the third brake wheel cylinder 31, thereby achieving control of the pressure of the third brake wheel cylinder 31; the fourth inlet valve 42 is used to control the brake fluid flow rate flowing into the fourth brake wheel cylinder 41, and the fourth outlet valve 43 is used to control the brake fluid flow rate flowing out of the fourth brake wheel cylinder 41, thereby achieving 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 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 liquid inlet valve 12, the first liquid outlet valve 13, the second liquid inlet valve 22, the second liquid outlet valve 23, the third liquid inlet valve 32, the third liquid outlet valve 33, the fourth liquid inlet valve 42, and the fourth liquid outlet valve 43.

[0150] Obviously, the above embodiments are merely example for clearly illustrating, and are not limitation to the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments are not required to be enumerated, and the obvious changes or variations derived from the above are still within the protection scope of the present application.

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 based on 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 based on the vehicle lateral position deviation; Defining a set of effective control vectors for the inlet and outlet valves and a set of effective flow vectors for the corresponding wheel-cylinder groups based on the on / off states of the solenoid valves, and establishing a dynamic equation for the wheel-cylinder group flow vectors to the vehicle's yaw motion state based on the effective flow vectors for the wheel-cylinder groups; 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 desired yaw angle and the equivalent desired 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: Before obtaining the reference path information, the vehicle status information and the hydraulic brake system status information, the following steps are further included: 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 pressure of the high-pressure supply device, the pressure of the low-pressure return oil device and the pressures of the four wheel cylinders.

4. The vehicle path tracking prediction control method according to claim 3, characterized in that: 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 includes: 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; Calculating an equivalent desired yaw angle based on 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 desired yaw rate is calculated according to a first-order derivative of the equivalent desired 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 switching 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. Define the control vectors of the inlet valve and the outlet valve according to the switching 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, 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 are defined; A dynamic equation of the wheel-cylinder group flow vector to the vehicle yaw motion state is established based on 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: The method of predicting 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: 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 based on the equivalent desired yaw angle and the equivalent desired yaw angular velocity, and solving an optimal prediction value using the cost function as an optimization target to achieve control of the vehicle yaw motion includes: Establishing a cost function according to the equivalent desired yaw angle and the equivalent desired yaw rate; Solving the optimization problem with the cost function as the optimization objective to determine the optimal prediction value; The optimal wheel-brake cylinder group flow vector and the corresponding inlet valve and outlet valve group control vectors are obtained based on the optimal prediction value to control the inlet valve and outlet valve group to open or close, thereby achieving control of the vehicle's yaw motion.

8. A vehicle path tracking prediction control device, characterized in that: include: A function trigger module is used to monitor the enable signal of the differential path tracking function, and when the enable signal is true, start the differential path tracking control function, otherwise continue monitoring; A data processing module is used to obtain reference path information, vehicle status information and hydraulic brake system status information; a desired yaw motion calculation module, configured to calculate a vehicle lateral position deviation based on the reference path information, the vehicle state information, and the hydraulic brake system state information, and to calculate an equivalent desired yaw angle and an equivalent desired yaw angular velocity based on the vehicle lateral position deviation; a yaw motion model establishment module, configured to define a set of effective control vectors for the inlet and outlet valves and the corresponding effective flow vectors for the wheel cylinder group based on the on / off states of the solenoid valves, and to establish a dynamic equation for the wheel cylinder group flow vector to the vehicle's yaw motion state based on the effective flow vectors for the wheel cylinder group; a yaw motion prediction module, configured to predict the vehicle yaw motion state in a future control cycle based on the dynamic equation and the effective flow vector set of the wheel cylinder group; The cost function evaluation module is used to establish a cost function based on 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 achieve 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 includes a pressure sensor, a liquid inlet valve, a liquid outlet valve, and a brake wheel cylinder; 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 according to 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-voltage supply device includes a high-voltage accumulator type high-voltage supply device and an electric-powered master cylinder type high-voltage supply device.

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