Road vehicle consist and method of controlling the same

Abstract

The present application belongs to the field of vehicle technology, and discloses a highway vehicle formation and a control method thereof. The highway vehicle formation comprises a tractor and a trailer. The tractor is provided with a control unit. The trailer is detachably connected to the tractor, and is provided with a controller. The trailer is any one of a semitrailer, a full trailer, a center-axle trailer, or a combination of a power chassis and a semitrailer. The controller is in communication connection with the control unit. The highway vehicle formation of the present application is in communication connection with the control unit of the tractor through the controller arranged on the trailer, so that the tractor can control the trailer, and the safety of the trailer in driving is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vehicle technology, in particular to a highway vehicle formation and a control method thereof. BACKGROUND

[0002] The common highway vehicle formation is in the form of a tractor and a non-powered trailer. The tractor is responsible for the control of the vehicle formation, including steering, acceleration and braking control. The braking control can be the tractor alone braking or the tractor and trailer jointly braking (the trailer receiving the braking instruction of the tractor).

[0003] The combination of the highway vehicle tractor and the non-powered trailer has a great safety hazard due to the control problem of the non-powered trailer. The hazard is more dangerous with the increase of the number or length of the trailer and the increase of the driving speed of the vehicle. Meanwhile, the control problem of the non-powered trailer also causes many other inconveniences, such as too large steering radius, which greatly restricts the application scene range of the combination of the tractor and multiple trailers. SUMMARY

[0004] The present application aims to provide a highway vehicle formation and a control method thereof to solve the problems of low safety and difficult control of the combination of the tractor and the non-powered trailer.

[0005] To achieve this purpose, the present application adopts the following technical solutions:

[0006] The highway vehicle formation comprises:

[0007] a tractor, wherein the tractor is provided with a control unit;

[0008] a trailer, wherein the trailer is detachably connected to the tractor, the trailer is provided with a controller, the trailer is any one or more of a semitrailer, a full trailer, a center-axle trailer or a combination of a powered chassis and a semitrailer, and the controller is in communication connection with the control unit.

[0009] Optionally, the trailer is provided with a plurality of trailers, and the front end of each trailer is hingedly connected to the front trailer or the tractor.

[0010] Optionally, the combination of the powered chassis and the semitrailer comprises a powered chassis and a vehicle body, the front end of the powered chassis is hingedly connected to the tractor or connected to the front trailer, and the rear end of the powered chassis is provided with a grinding disc, and the grinding disc is hingedly connected to the front end of the vehicle body.

[0011] Optionally, the trailer further comprises any one or more of a driving mechanism, a steering module, a braking module, a sensing module and an energy storage module, and the driving mechanism, the steering module, the braking module, the sensing module and the energy storage module are respectively in communication connection with the control unit or the controller.

[0012] Optionally, the controller on each trailer is communicatively connected to the controller of the front adjacent trailer, and the controller of the first trailer is communicatively connected to the control unit;

[0013] Or,

[0014] The controller on each trailer is communicatively connected to the control unit, respectively.

[0015] Optionally, the trailer further comprises a pantograph, which is in contact with an overhead contact system to charge the energy storage module, and the energy storage module provides electric energy for the driving mechanism.

[0016] Optionally, the energy storage module is a long-time energy storage module or a short-time energy storage module.

[0017] Optionally, the long-time energy storage module is a battery, and the short-time energy storage module is a super capacitor.

[0018] Optionally, the driving mechanism, the steering module, the braking module and the perception module are respectively provided with a plurality of, and are selectively arranged on the wheels, axles and / or bodies of the trailer.

[0019] A control method of a highway vehicle consist, for controlling the highway vehicle consist, the control method of the highway vehicle consist comprising the following steps:

[0020] S1, the control unit of the tractor acquires the information of the marking line, the body state, the position and the road condition, and calculates the target speed and the target heading angle;

[0021] S2, the control unit performs nonlinear optimization on the target speed and the target heading angle, and obtains the optimized values of the target speed and the target heading angle according to the cost function and the constraint condition;

[0022] The cost function comprises:

[0023] Stable steering, minimum rate of change of angular velocity between the tractor and the trailer;

[0024] Stable combination body posture, minimum angular velocity difference between the tractor and the trailer, and between the trailers;

[0025] Stable acceleration, minimum rate of change of acceleration of the tractor;

[0026] Tracking the center line of the lane, minimum position and orientation difference between the tractor and the center line of the lane;

[0027] Stable cruising, minimum difference between the speed of the highway vehicle consist and the road speed limit;

[0028] The constraint conditions include:

[0029] A curvature speed limit, the vehicle speed of the towing vehicle is less than the maximum vehicle speed of the trajectory curvature of the trailer and the maximum acceleration limit;

[0030] An obstacle speed limit, the vehicle speed of the towing vehicle is less than the maximum vehicle speed provided by the obstacle avoidance decision;

[0031] Obstacle avoidance, the polygon of the highway vehicle consists of a safe redundant distance from the boundary line of the driving area provided by the obstacle avoidance decision;

[0032] S3, the control unit calculates the motor torque, brake torque, wheel rotation angle control instruction, estimated vehicle speed and estimated heading angle of the towing vehicle based on PID feedback control and MPC model predictive control according to the optimized values of the target speed and target heading angle, and sends the estimated vehicle speed and estimated heading angle of the towing vehicle to the rear trailer.

[0033] Optionally, the control method of the highway vehicle consists of the following steps S4:

[0034] S4, the controller of the trailer calculates its own motor torque, brake torque, wheel rotation angle control instruction, estimated vehicle speed and estimated heading angle based on PID feedback control and MPC model predictive control according to the received estimated vehicle speed and estimated heading angle sent by the front control unit;

[0035] Or,

[0036] The controller of the trailer calculates its own motor torque, brake torque, wheel rotation angle control instruction, estimated vehicle speed and estimated heading angle based on PID feedback control and MPC model predictive control according to the received estimated vehicle speed and estimated heading angle sent by the controller of the front trailer, and sends its own estimated vehicle speed and estimated heading angle to the controller of the rear trailer.

[0037] The beneficial effects of the present application are:

[0038] The highway vehicle consists of a driving mechanism arranged on the trailer, so that the control unit of the towing vehicle can control the driving mechanism, thereby realizing wheel driving control of the trailer, improving the safety of the trailer driving, and increasing the overall driving power, which is beneficial to improve the overall driving speed of the highway vehicle consists of. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 is a schematic diagram of the highway vehicle consists of the present application Figure 1 ;

[0040] Figure 2 is a schematic diagram of the communication connection mode of the control unit and the driving mechanism in the highway vehicle consist of the present application;

[0041] Figure 3 is a schematic diagram of the communication connection mode of the control unit, the controller and the driving mechanism in the highway vehicle consist of the present application;

[0042] Figure 4 is a schematic diagram of the communication connection mode of the control unit and the controllers of the plurality of trailers in the highway vehicle consist of the present application;

[0043] Figure 5 is a schematic diagram of the communication connection mode of the functional modules of the tractor and the trailer in the highway vehicle consist of the present application;

[0044] Figure 6 is a schematic diagram of the composition of the highway vehicle consist of the present application Figure 2 .

[0045] In the drawings:

[0046] 1, tractor; 11, control unit;

[0047] 2, trailer; 21, driving mechanism; 22, power chassis; 23, vehicle body; 24, controller; 25, steering module; 26, braking module; 27, sensing module; 28, energy storage module; 29, pantograph. DETAILED DESCRIPTION

[0048] The present application will be further described below in conjunction with the drawings and examples. It can be understood that the specific examples described herein are only used to explain the present application, and not to limit the present application. In addition, it should be noted that, for the convenience of description, only the parts related to the present application are shown in the drawings, not all the structures.

[0049] In the description of the present application, unless otherwise explicitly specified and limited, the terms "connected", "connected", "fixed" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0050] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature can include that the first and second features are in direct contact, or can include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "over" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher in horizontal height than the second feature. The first feature "under", "below" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the first feature is lower in horizontal height than the second feature.

[0051] In the description of the present embodiment, the terms "upper", "lower", "right", "left", and other orientation or position relationships are based on the orientation or position relationships shown in the drawings, and are only for the convenience of description and simplification of operation, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0052] The present embodiment provides a highway vehicle formation, comprising a tractor 1 and a trailer 2, the tractor 1 is provided with a control unit 11, the trailer 2 is detachably connected to the tractor 1, the trailer 2 is any one or more of a semitrailer, a full trailer, a center axle trailer or a combination of a power chassis and a semitrailer, and the controller 24 is in communication connection with the control unit 11.

[0053] As shown in Figure 1 When one tractor 1 is matched with multiple trailers 2, the controller 24 of each trailer 2 is in communication connection with the control unit 11, realizing the control of the tractor 1 on the multiple trailers 2. Generally, the control unit 11 is a vehicle-mounted control unit or a vehicle-mounted computer arranged on the tractor 1, by arranging the controller 24 on the trailer 2, the communication control of the control unit 11 of the tractor 1 on the controller 24 is facilitated, such as when the driving mechanism 21 is arranged on the trailer 2, the driving mechanism 21 can be controlled through the controller 24, thereby realizing the wheel driving control of the trailer 2, improving the safety of the trailer driving, and the overall driving power is flexible and controllable, which is beneficial to improve the overall driving speed of the highway vehicle formation and has higher safety. It can be understood that the trailer 2 has the driving mechanism 21, which changes the non-powered trailer in the prior art into a powered trailer, the overall power of the trailer 2 is increased, and the control unit 11 on the tractor 1 is uniformly controlled, which is beneficial to improve the overall controllability of the highway vehicle formation, including speed control and turning differential control, etc., and the driving safety of the highway vehicle formation is greatly improved.

[0054] Optionally, the trailer 2 is provided with multiple trailers 2, and the front end of each trailer 2 is hinged to the front trailer 2 or the tractor 1.

[0055] As Figure 1 and Figure 6 shown, the trailer 2 is provided with a plurality of, a plurality of trailers 2 in turn hinged, the first trailer 2 is connected to the tractor 1, each trailer 2 behind the hinge of the trailer 2 in front of it. In the prior art, the trailer 2 is hinged to the tractor 1, because of the uncontrollability of the unpowered trailer, a tractor 1 can generally only carry one trailer 2, and can only drive on ordinary roads. By providing a controller 24 on the trailer 2, and changing the unpowered trailer to a powered trailer, etc., the driving speed of the trailer 2 is controllable, and the turning radius can be controlled by the differential speed of the inner and outer wheels or the active steering of the rear wheels of the trailer 2, so the overall driving safety of the highway vehicle formation is greatly improved, and the number n of trailers 2 behind a tractor 1 can be increased as needed, n is a positive integer, and each trailer 2 is hinged to the trailer 2 in front of it, thereby improving the carrying capacity of the highway vehicle formation and reducing transportation costs. The trailer 2 can be a semitrailer, a full trailer, or a center axle trailer, or a combination of a powered chassis and a semitrailer, as shown in Figure 2 , for example, a plurality of driving mechanisms 21 are provided on a plurality of trailers 2, and the plurality of driving mechanisms 21 are connected to the control unit 11 through the controller 24 or directly connected to the control unit 11, realizing comprehensive centralized control of the driving mechanisms 21 of the plurality of trailers 2 by the control unit 11, forming a highway vehicle formation with powered trailers.

[0056] In one trailer configuration, as shown in Figure 1 , the trailer 2 includes a powered chassis 22 and a vehicle body 23, the front end of the powered chassis 22 is provided with a hinge point A to hinge the tractor 1 or connect the vehicle body 23 of the trailer 2 in front of it, and the rear end of the powered chassis 22 is provided with a grinding disc, which is hinged to the front end of the vehicle body 23. Compared with the vehicle head of the traditional tractor 1, the powered chassis 22 has a shorter wheelbase, a more compact and simple power layout. The front and rear axles have independent or cooperative steering capability. The front end of the powered chassis 22 is provided with a hinge point A, which can be hinged to the trailer 2 in front of it. The rear end of the powered chassis 22 is provided with a grinding disc, which is hinged to the vehicle body 23. It can be understood that the trailer 2 composed of the powered chassis 22 and the unpowered vehicle body 23, the driving mechanism 21 is arranged on the powered chassis 22, and a plurality of trailers 2 are connected in series, which is beneficial to the simple improvement of the existing unpowered trailer to obtain a powered trailer, and the modification cost is low and easy to implement.

[0057] As shown in Figure 6 , the second trailer configuration, the trailer 2, is replaced by a combination of a powered chassis 22 and a semitrailer into a full trailer configuration, wherein the full trailer is hinged to the front tractor 1 or the front full trailer.

[0058] Optionally, the trailer 2 may also include any one or more of a drive mechanism 21, a steering module 25, a braking module 26, a sensing module 27, and an energy storage module 28, wherein the drive mechanism 21, the steering module 25, the braking module 26, the sensing module 27, and the energy storage module 28 are respectively communicatively connected to the control unit 11 or the controller 24.

[0059] like Figure 3 As shown, in some embodiments, taking the drive mechanism 21 as an example, each trailer 2 is equipped with a separate controller 24 to control the operation of the drive mechanism 21 on that trailer 2. The controller 24 of the trailer 2 is connected to the control unit 11 of the tractor 1, which simplifies the connection wiring and control method. The control unit 1 only needs to communicate with the controllers 24 of each trailer 2 to send commands. It should be noted that in this invention, the communication connection methods include wired and wireless connections. Wireless communication is preferred between the controller 24 and the control unit 11, while a wired connection is preferred between the controller 24 and the drive mechanism 21. Figure 4 In the illustrated embodiment, controllers 24 on multiple trailers 2 are respectively communicatively connected to control unit 11 in a parallel communication connection manner. When a trailer 2 is equipped with one or more of the following: drive mechanism 21, steering module 25, braking module 26, sensing module 27, and energy storage module 28, the steering module 25, braking module 26, sensing module 27, and energy storage module 28 are all connected to the controllers 24 on that trailer 2. The controllers 24 then communicate with control unit 11, which helps reduce data interaction with control unit 11, improves data reliability, and allows trailer 2 to independently receive and process data under the control commands of controller 24, thus reducing the data processing load on control unit 11 and improving control efficiency. Figure 5 In the illustrated embodiment, the drive mechanism 21, steering module 25, braking module 26, sensing module 27, and energy storage module 28 on each trailer 2 are communicatively connected to the control unit 11. This connection method increases the workload of the control unit 11 in receiving and processing data, but the control method is more precise and faster. However, it requires more transmission links or lines, thus complicating the connection. When more drive mechanisms 21 or braking modules 26 are added to each trailer 2, the connection and control become even more complex. In this case, a more sophisticated approach is adopted... Figure 4 The arrangement shown allows each trailer 2 to have independent data processing capabilities, which simplifies wiring and improves the processing efficiency of the control unit 11. It should be noted that multiple drive mechanisms 21, steering modules 25, braking modules 26, sensing modules 27, and energy storage modules 28 can be installed on each trailer 2, each connected to the controller 24 installed on that trailer 2. This allows for the formation of an independent control system for each trailer 2 before communication with the control unit 11, resulting in better control performance and simpler, more convenient communication.

[0060] Optionally, the controller 24 on each trailer 2 is communicatively connected to the controller 24 of the adjacent trailer 2 in front, and the controller 24 of the first trailer 2 is communicatively connected to the control unit 11; or, the controller 24 on each trailer 2 is communicatively connected to the control unit 11 respectively.

[0061] like Figure 3 As shown, when multiple trailers 2 are set behind a tractor unit 1, the multiple trailers 2 are connected in series sequentially. Correspondingly, if the controllers 24 are also connected in series sequentially for communication, it conforms to the overall driving characteristics of highway vehicle formations, which is conducive to control and has higher control accuracy. Under this connection method, each controller 24 recursively derives the estimated heading angle of the front based on the turning command and model of the front control unit 11 or the front controller 24, and sends it to the rear controller 24. It can be understood that when the highway vehicle formation is in motion, the driving path and turning data of the front tractor unit 1 or trailer 2 are sent to the trailers 2 behind, which helps the trailers 2 behind to follow the path and turning data of the front tractor unit 1 or trailer 2. The overall control method is more reliable and easier to implement, and safety is improved.

[0062] Optionally, the trailer 2 also includes a pantograph 29, which contacts the overhead contact line to charge the energy storage module 28, which provides power to the drive mechanism 21.

[0063] like Figure 6 As shown, the pantograph 29 is located on the top of the trailer 2 and is a dual-source pantograph. When there is an overhead contact line, the pantograph 29 can be raised to charge the energy storage module 28. The energy storage module 28 can be a long-term energy storage module, such as a lithium battery, to provide autonomous driving capability for the trailer 2 without external energy input. Alternatively, a short-term energy storage module, such as a supercapacitor, can be used simultaneously or alone to reduce the impact of sudden large energy fluctuations and high-frequency charging and discharging on the performance and lifespan of the lithium battery.

[0064] Optionally, multiple drive mechanisms 21, steering modules 25, braking modules 26 and sensing modules 27 are provided, selectively installed on the wheels, axles and / or body 23 of the trailer 2.

[0065] Taking the driving mechanism 21 as an example, when a plurality of driving mechanisms 21 are provided, the output ends of the plurality of driving mechanisms 21 are respectively provided to be connected to a plurality of wheels or axles of the trailer 2 as wheel-side motors, and the driving of each wheel can be independently controlled. The plurality of driving mechanisms 21 are separately provided or the driving mechanism 21 is combined with the brake module 26 to be provided, so that the steering control can be realized, and the brake energy recovery can be realized. Meanwhile, the brake module 26 provided on the wheel or the axle can also independently control the braking of each wheel to realize the independent driving and independent braking of each wheel. The sensing module 27 includes a pressure sensor, an inertial navigation instrument and an angle sensor, etc. The inertial navigation instrument is a multi-axis inertial navigation unit, which is arranged on the vehicle body 23 such as a girder of the trailer 2, and is used for measuring the attitude of the vehicle body 23. The pressure sensor is arranged on the suspension system of each wheel to monitor or judge the center change of the vehicle body 23. The tire pressure sensor of each wheel can measure the pressure of the tire. The angle between the power chassis 22 and the vehicle body 23 of each trailer 2. The communication and cooperation of each module with the tractor 1 and other trailers 2, and the autonomous control of the driving force and the braking force of the wheel, so as to realize the self-stabilization of the trailer 2 and the cooperation with other trailers 2 and the tractor 1.

[0066] The embodiment of the present application also provides a control method of a highway vehicle consist, which is used for controlling the highway vehicle consist, and the control method of the highway vehicle consist comprises the following steps:

[0067] S1, the control unit 11 of the tractor 1 collects the marking line information, the vehicle body state information (including the vehicle body attitude), the position information (including the map information) and the road condition information (including the road use party and the road occupation party), and calculates the target speed and the target heading angle according to the above information;

[0068] S2, the control unit 11 performs nonlinear optimization on the target speed and the target heading angle to obtain the optimized value of the target speed and the target heading angle according to the cost function and the constraint condition;

[0069] The cost function comprises:

[0070] Stable steering, the minimum change rate of the angular velocity between the tractor 1 and the trailer 2 and the minimum change rate of the angular velocity between the trailers 2;

[0071] Stable combination body attitude, the minimum difference of the angular velocity between the tractor 1 and the trailer 2 and the minimum difference of the angular velocity between the trailers 2;

[0072] Stable acceleration, the minimum change rate of the acceleration of the tractor 1;

[0073] Tracking the lane center line, the minimum difference of the position and orientation of the tractor 1 and the lane center line;

[0074] Stable cruise, the minimum difference of the speed of the highway vehicle consist and the road speed limit;

[0075] The constraints include:

[0076] a curvature speed limit, the vehicle speed of the towing vehicle 1 is less than the maximum vehicle speed of the trajectory curvature of the trailer 2 and the maximum acceleration limit;

[0077] an obstacle speed limit, the vehicle speed of the towing vehicle 1 is less than the maximum vehicle speed provided by the obstacle avoidance decision;

[0078] an obstacle avoidance, the polygon of the highway vehicle consist and the driving area boundary line provided by the obstacle avoidance decision maintain a safe redundant distance.

[0079] S3, the control unit 11 calculates the motor torque, brake torque, wheel steering angle control instruction, estimated vehicle speed and estimated heading angle of the towing vehicle 1 based on PID feedback control and MPC model predictive control according to the optimized values of target speed and target heading angle, and sends the estimated vehicle speed and estimated heading angle of the towing vehicle 1 to the rear trailer 2. The driving mechanism 21 of the rear trailer 2 performs driving control according to the estimated vehicle speed and estimated heading angle. When the rear trailer 2 has a controller 24, the control unit 11 and the controller 24 are communicatively connected to control the actuation of the driving mechanism 21.

[0080] For the highway vehicle consist provided with the controller 24 of the trailer 2, the control method of the highway vehicle consist of the application further includes step S4, which is divided into two cases:

[0081] The first kind: the controller 24 of the current one or more trailers 2 receives the estimated vehicle speed and estimated heading angle sent by the control unit 11 of the towing vehicle 1, and the controller 24 of the current one or more trailers 2 calculates its own motor torque, brake torque, wheel steering angle control instruction, estimated vehicle speed and estimated heading angle based on PID feedback control and MPC model predictive control; and then drives according to its own motor torque, brake torque and wheel steering angle control instruction.

[0082] The second kind: the controller 24 of the current trailer 2 sends its own estimated vehicle speed and estimated heading angle to the controller 24 of the rear trailer 2, and the controller 24 of the rear trailer 2 calculates its own motor torque, brake torque, wheel steering angle control instruction, estimated vehicle speed and estimated heading angle based on PID feedback control and MPC model predictive control, and sends its own estimated vehicle speed and estimated heading angle to the controller of the rear trailer.

[0083] The polygon of the highway vehicle formation refers to a convex polygon formed by connecting the peripheral edges of the highway vehicle formation. The control method of the highway vehicle formation, in some embodiments, adopts a distributed speed and attitude control of the tractor 1 and the trailer 2 based on the combination of PID feedback control and nonlinear MPC (model predictive control), and outputs the motor torque, brake torque and wheel rotation angle control instructions to each trailer 2 through the target speed and target heading angle provided by the control unit 11. When the controller 24 of the tractor 1 and the trailer 2 is in a series structure, the heading angle estimation value of the front vehicle is recursively calculated according to the rotation angle command of the front vehicle controller 24 and the model; then the heading angle estimation value of the front vehicle is used as the input of the rear vehicle. The advantage is that when the tractor 1 turns, the active steering of the trailer 2 can greatly reduce the turning radius of the whole highway vehicle formation. Compared with the non-powered trailer in the prior art, the turning radius of the highway vehicle formation with the powered trailer provided by the embodiment of the present application can be reduced by 12.8%-29.3% when the rear axle rotation angle of the trailer 2 is in the range of 5-15°.

[0084] Obviously, the above embodiments of the present application are only examples for clear illustration of the present application, and are not intended to limit the embodiments of the present application. Those skilled in the art can make various obvious changes, readjustments and substitutions without departing from the protection scope of the present application. It is unnecessary and impossible to enumerate all the embodiments here. Any modification, equivalent substitution and improvement within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A method for controlling highway vehicle formation, wherein the highway vehicle formation includes: Tractor (1), wherein the tractor (1) is equipped with a control unit (11); Trailer (2), the trailer (2) is detachably connected to the tractor (1), the trailer (2) is equipped with a controller (24); the trailer (2) is any one or more of a semi-trailer, a full trailer, a center axle trailer or a combination of a power chassis and a semi-trailer; the controller (24) is communicatively connected to the control unit (11); The control method for highway vehicle formation includes the following steps; S1, the control unit (11) of the tractor (1) collects the marking line information, vehicle status information, position information and road condition information, and calculates the target speed and target heading angle; S2, the control unit (11) performs nonlinear optimization on the target speed and the target heading angle, and obtains the optimized values ​​of the target speed and the target heading angle according to the cost function and constraints; The cost function includes: Stable steering, with minimal rate of change of angular velocity of the tractor (1) and trailer (2); The angular velocity difference between the tractor (1) and the trailer, and between the trailers (2) and each other is minimized to stabilize the attitude of the combined vehicle. During stable acceleration, the rate of change of acceleration of the tractor (1) is minimal; The position and orientation difference between the tractor (1) and the lane centerline is minimized when the lane centerline is tracked. Stable cruise is achieved when the difference between the vehicle speed of the highway vehicle formation and the road speed limit is minimized. The constraints include: Curvature speed limit: the speed of the tractor (1) is less than the maximum speed of the trailer (2) due to the trajectory curvature and the maximum acceleration limit. The obstacle has a speed limit, and the speed of the tractor (1) is less than the maximum speed provided by the obstacle avoidance decision. Obstacle avoidance: The polygon of the highway vehicle formation and the boundary line of the driving area provided by the obstacle avoidance decision maintain a safe redundancy distance. S3, the control unit (11) calculates the motor torque, braking torque, wheel angle control command, estimated speed and estimated heading angle of the tractor (1) based on the optimized values ​​of the target speed and target heading angle, using PID feedback control and MPC model predictive control, and sends the estimated speed and estimated heading angle of the tractor (1) to the trailer (2) behind it.

2. The method for controlling highway vehicle formation according to claim 1, characterized in that, The trailer (2) is provided in multiple ways, and the front end of each trailer (2) is hinged to the trailer (2) in front or the tractor (1).

3. The method for controlling highway vehicle formation according to claim 1 or 2, characterized in that, The combination of the power chassis and semi-trailer includes a power chassis (22) and a vehicle body (23). The front end of the power chassis (22) is hinged to the tractor (1) or the trailer (2) in front. The rear end of the power chassis (22) is provided with a grinding disc, which is hinged to the front end of the vehicle body (23).

4. The method for controlling highway vehicle formation according to claim 1, characterized in that, The trailer (2) also includes any one or more of a drive mechanism (21), a steering module (25), a braking module (26), a sensing module (27), and an energy storage module (28), wherein the drive mechanism (21), the steering module (25), the braking module (26), the sensing module (27), and the energy storage module (28) are respectively connected to the control unit (11) or the controller (24).

5. The method for controlling highway vehicle formation according to claim 4, characterized in that, The controller (24) on each trailer (2) is communicatively connected to the controller of the adjacent trailer (2) in front, and the controller (24) of the first trailer (2) is communicatively connected to the control unit (11); or, The controller (24) on each trailer (2) is communicatively connected to the control unit (11).

6. The method for controlling highway vehicle formation according to claim 4, characterized in that, The trailer (2) also includes a pantograph that contacts the overhead contact line to charge the energy storage module (28), which provides power to the drive mechanism (21).

7. The method for controlling highway vehicle formation according to claim 6, characterized in that, The energy storage module (28) can be a long-term energy storage module or a short-term energy storage module.

8. The method for controlling highway vehicle formation according to claim 7, characterized in that, The long-term energy storage module is a battery, and the short-term energy storage module is a supercapacitor.

9. The method for controlling highway vehicle formation according to claim 5, characterized in that, The drive mechanism (21), the steering module (25), the braking module (26) and the sensing module (27) are provided in multiples, and are selectively installed on the wheels, axles and / or body of the trailer (2).

10. The method for controlling highway vehicle formation according to claim 1, characterized in that, It also includes step S4: S4, the controller (24) of the trailer (2) calculates its own motor torque, braking torque, wheel angle control command, estimated vehicle speed and estimated heading angle based on the estimated vehicle speed and estimated heading angle sent by the control unit (11) ahead, and based on PID feedback control and MPC model predictive control. or, The controller (24) of the trailer (2) calculates its own motor torque, braking torque, wheel angle control command, estimated speed and estimated heading angle based on PID feedback control and MPC model predictive control, according to the estimated vehicle speed and estimated heading angle sent by the controller (24) of the trailer (2) ahead. The controller (24) then sends its own estimated vehicle speed and estimated heading angle to the controller (24) of the trailer (2) behind.

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