Control method and control system for automatic reversing of a vehicle with trailer

Abstract

The present application relates to a control method and a control system for automatic reversing of a vehicle with trailer, the control method comprising the following steps: S1: establishing a linear two-degree-of-freedom kinematic model of the vehicle with trailer; S2: giving a set hitch angle of the trailer to the towing vehicle; S3: giving a target path of the trailer; S4: detecting a current actual hitch angle θ of the trailer to the towing vehicle; S5: comparing the actual hitch angle θ with the set hitch angle, in a backing section of the target path, if the actual hitch angle θ reaches or exceeds the set hitch angle then S51: calculating a front wheel steering angle δ of the towing vehicle based on the actual hitch angle θ and the set hitch angle by means of a hitch angle controller v , otherwise S52: calculating the front wheel steering angle δ of the towing vehicle based on the actual hitch angle θ and a target turning radius r t of the trailer by means of a turning radius controller v , controlling a steering wheel angle of the towing vehicle based on the front wheel steering angle δ v .

Description

Technical Field

[0001] The present invention relates to a control method for automatic reversing of a vehicle with a trailer, and a control system for performing such a control method. Background Technology

[0002] Reversing a truck or car with a trailer is considered quite difficult during everyday driving. For example, when parallel parking or reversing into a parking space, the driver needs to turn the steering wheel in the opposite direction to control the trailer's direction, which is especially difficult for inexperienced drivers. Additionally, when reversing, the trailer will swing relative to the towing vehicle around the articulation point; if the towing angle between the towing vehicle and the trailer exceeds the limit, there is a risk of the trailer folding over.

[0003] Currently, research and patents related to automatic parking lack solutions that incorporate trailer reversing control. Existing solutions for trailer reversing control rely heavily on computationally intensive methods like MPC (Model Predictive Control). Furthermore, relying solely on the trailer angle for reversing can lead to untimely tracking, while relying solely on the turning radius can cause the trailer angle to exceed its limit. Overall, there is no solution for achieving automatic parking through continuous reversing and trajectory tracking. Summary of the Invention

[0004] One objective of one aspect of the invention is to provide a control method for automatic reversing of a vehicle with a trailer, the control method being able to effectively avoid the dangerous situation of trailer folding.

[0005] According to one aspect of the present invention, a control method for automatic reversing of a vehicle with a trailer includes the following steps:

[0006] S1: Establish a linear two-degree-of-freedom kinematic model of the vehicle with trailer;

[0007] S2: Set the towing angle between the trailer and the tractor.

[0008] S3: Given the target path of the trailer;

[0009] S4: Detect the current actual towing angle θ between the trailer and the tractor;

[0010] The control method further includes the following steps:

[0011] S5: Compare the actual towing angle θ with the set towing angle In a comparison, if the actual towing angle θ reaches or exceeds the set towing angle in the backward segment of the target path... Then S51: Using a towing angle controller, based on the actual towing angle θ and the set towing angle To calculate the steering angle δ of the front wheels of the tractor v Otherwise, S52: using a turning radius controller based on the actual towing angle θ and the target turning radius r of the trailer. t To calculate the steering angle δ of the front wheels of the tractor v Based on the front wheel steering angle δ v To control the steering wheel angle of the tractor unit.

[0012] According to one aspect of the present invention, a control method for automatic reversing of a vehicle with a trailer is provided, wherein the set towing angle given in step S2 is... Less than the limit towing angle θ between the tractor and the trailer max If in step S5 it is determined that the actual towing angle θ reaches or exceeds the set towing angle Then, proceed to step S6: using the turning radius controller to predict the towing angle between the trailer and the tractor. If the towing angle between the trailer and the tractor shows an increasing trend, proceed to step S51. If the towing angle between the trailer and the tractor shows a decreasing trend, proceed to step S52.

[0013] According to one aspect of the present invention, a control method for automatic reversing of a vehicle with a trailer is provided, which calculates the target turning radius r of the trailer in the reversing section by means of a pre-aiming and tracking method. t :

[0014]

[0015] Where s is the offset distance, which is the component of the distance between the midpoint of the trailer's wheel axle and the pre-aiming point on the transverse axis perpendicular to the longitudinal axis;

[0016] d represents the aiming distance, which is the component of the distance between the midpoint of the trailer's wheel axle and the aiming point along the longitudinal axis of the trailer.

[0017] According to one aspect of the present invention, in the control method for automatic reversing of a vehicle with a trailer, the steering angle δ of the front wheel of the tractor in step S52 is... v The calculation method is as follows:

[0018]

[0019] Among them, l v This is the distance from the drive wheels to the steering wheels of the tractor unit;

[0020] c v This is the distance from the drive wheel of the tractor to the articulation point;

[0021] c t This is the distance from the center of the trailer's axle to the hinge point.

[0022] According to one aspect of the present invention, in the control method for automatic reversing of a vehicle with a trailer, the steering angle δ of the front wheel of the tractor in step S51 is... v The calculation method is as follows:

[0023]

[0024] Where k is a constant.

[0025] According to one aspect of the present invention, a control method for automatic reversing of a trailer vehicle is provided, wherein the target path further includes a forward section, and the control method further includes step S7: during the forward section, the towing angle controller is based on the actual towing angle θ and the target towing angle θ. t To calculate the steering angle δ of the front wheels of the tractor v .

[0026] According to one aspect of the present invention, a control method for automatic reversing of a vehicle with a trailer is provided, which calculates the target towing angle θ of the trailer in the forward section by means of a pre-aiming and tracking method. t The target towing angle θ t as follows:

[0027]

[0028] Among them, c t This is the distance from the center of the trailer's axle to the hinge point;

[0029] s is the offset distance, which is the component of the distance between the midpoint of the trailer's wheel axle and the pre-aiming point on the transverse axis perpendicular to the longitudinal axis;

[0030] d represents the aiming distance, which is the component of the distance between the midpoint of the trailer's wheel axle and the aiming point along the longitudinal axis of the trailer.

[0031] According to one aspect of the present invention, in the control method for automatic reversing of a vehicle with a trailer, the steering angle δ of the front wheel of the tractor in step S7 is... v The calculation method is as follows:

[0032]

[0033] Where k is a constant, a proportionality coefficient, representing the response speed of the towing angle between the tractor and the trailer;

[0034] l v This is the distance from the drive wheels to the steering wheels of the tractor unit.

[0035] c t This is the distance from the center of the trailer's axle to the hinge point;

[0036] c v The distance from the drive wheel of the tractor to the articulation point; and

[0037] When the calculated target towing angle θ t Greater than the set towing angle At that time, let the target towing angle θ t Equal to the set towing angle

[0038] According to one aspect of the present invention, a control method for automatic reversing of a vehicle with a trailer is provided, wherein the limit towing angle θ between the trailer and the tractor is... max The calculation method is as follows:

[0039]

[0040] Where, r v This is the minimum turning radius of the rear wheels of the tractor.

[0041] r H This is the minimum turning radius at the hinge point;

[0042] l v This is the distance from the drive wheels to the steering wheels of the tractor unit;

[0043] c v This is the distance from the drive wheel of the tractor to the articulation point;

[0044] c t This is the distance from the center of the trailer's axle to the hinge point;

[0045] δ vmax This is the maximum steering angle of the front wheels of the tractor.

[0046] According to one aspect of the present invention, a control method for automatic reversing of a trailer vehicle is provided, wherein the target path has a forward section and a reverse section, the intersection of the forward section and the reverse section is a first endpoint, and the final position of the set midpoint of the trailer wheel axle is a second endpoint. During the automatic reversing process, it is detected whether the midpoint of the trailer wheel axle has reached the first endpoint or the second endpoint, and when the first endpoint or the second endpoint is reached, a warning to change the driving direction or stop is issued.

[0047] According to one aspect of the present invention, a control method for automatic reversing of a trailer vehicle is provided, wherein a circular area is used to detect a first endpoint or a second endpoint, the first endpoint or the second endpoint being located on the circumference of the circular area and the target path passing through the center of the circular area, and a warning to change the driving direction or stop is issued when the midpoint of the trailer axle leaves the circular area after the midpoint of the trailer axle enters the circular area.

[0048] Furthermore, the present invention also proposes a control system for performing such a control method for automatic reversing of a trailer vehicle, the control system having interconnected communication links.

[0049] The detection module is used to detect the actual towing angle between the trailer and the tractor.

[0050] The comparison module is used to compare the detected towing angle with the set towing angle;

[0051] A towing angle controller is used to calculate the steering angle of the front wheels of the tractor based on the actual towing angle and the set towing angle;

[0052] A turning radius controller is used to calculate the steering angle of the tractor's front wheels based on the actual towing angle and the target turning radius of the trailer.

[0053] The advantages of the control method, control system, and vehicle for automatic reversing of a trailer vehicle according to this disclosure include: when the towing angle between the trailer and the tractor exceeds a given set towing angle, the control of the turning radius controller is deprived, and the towing angle is maintained within a certain range by the towing angle controller. The control method according to this disclosure can effectively prevent the dangerous situation of trailer folding during reversing. Attached Figure Description

[0054] Figure 1 The linear two-degree-of-freedom kinematic model of the trailer and the tractor is shown;

[0055] Figure 2 A flowchart illustrating a control method in a reversing segment according to a first embodiment of the present invention is shown;

[0056] Figure 3 A flowchart illustrating a control method in a reversing segment according to a second embodiment of the present invention is shown;

[0057] Figure 4 A schematic configuration diagram of the vehicle with trailer relative to the target path is shown;

[0058] Figure 5 A flowchart illustrating the control method in the forward section according to the present invention is shown;

[0059] Figure 6 A schematic diagram illustrating the detection of the first and second endpoints of the target path; and

[0060] Figure 7 A block diagram of the control system according to the present invention is shown. Detailed Implementation

[0061] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0062] The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly used in this specification are defined relative to the structures shown in the accompanying drawings. They are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive.

[0063] First, the term "trailer-equipped vehicle" should be defined. It refers to a tractor unit with a power source that provides towing capabilities, as well as a trailer without a power source. A trailer-equipped vehicle can be implemented as a truck with a trailer (also referred to as a trailer) integrated into its structure. Alternatively, it can be implemented as a combination of a separately constructed trailer and tractor unit, which in industrial applications can also be referred to as a towed mobile robot for transporting materials or products in a workshop.

[0064] Figure 1 A simplified linear two-degree-of-freedom kinematic model of a vehicle with a trailer is presented, assuming the front wheels of the tractor are steering wheels and the rear wheels are drive wheels, and the trailer is a single-axle trailer. The tractor and trailer are connected at hinge point O. In the assembled state, the trailer can rotate relative to the tractor about the hinge point. Typically, an angle sensor for detecting the towing angle between the trailer and the tractor is installed at this hinge point. Here, the "towing angle" refers to the angle between the longitudinal axis of the trailer body and the longitudinal axis of the tractor body. Figure 1 The towing angle is represented by θ. The towing angle can be used to evaluate the stability and safety of a vehicle during reversing. This is because when the towing angle exceeds the limit, no matter how the steering wheel is turned, the reversing behavior of the vehicle will cause the towing angle to increase, eventually leading to a dangerous situation of folding interference.

[0065] In the linear two-degree-of-freedom model, the influence of the steering system is ignored, and the steering angle of the front wheels of the tractor is considered directly. The suspension is also ignored; that is, the vehicle with the trailer (including the tractor and trailer) moves only in a plane parallel to the ground. In other words, the displacement along the z-axis of the vehicle coordinate system, the pitch angle about the y-axis, and the roll angle about the x-axis are all zero. During automatic reversing, due to the very low reversing speed, the effects of various accelerations, loads, and tire deformation and slippage are ignored. This linear two-degree-of-freedom model has only two degrees of freedom: lateral motion along the y-axis and yaw motion about the z-axis, and the vehicle speed is assumed to be constant. Therefore, the linear two-degree-of-freedom model can also be called a bicycle model or a two-wheeled motorcycle model.

[0066] The kinematic relationships of the kinematic model of the vehicle with a trailer according to the present invention are as follows:

[0067]

[0068] Among them, Ψ t The angle between the longitudinal axis of the trailer and the y-axis of the absolute coordinate system;

[0069] Ψ v The angle between the longitudinal axis of the tractor and the y-axis of the absolute coordinate system;

[0070] v is the speed of the rear wheels of the tractor;

[0071] δ v This refers to the steering angle of the front wheels of the tractor unit.

[0072] θ is the towing angle between the tractor and the trailer;

[0073] l v This is the distance from the drive wheels to the steering wheels of the tractor unit;

[0074] c v This is the distance from the drive wheel of the tractor to the articulation point;

[0075] c t This is the distance from the center of the trailer's axle to the hinge point.

[0076] The above formula applies to the situation of reversing into a parking space. When it comes to parallel parking, the above formula can be modified accordingly, which will not be explained in more detail.

[0077] The reversing process of a vehicle can typically include a backward movement or optionally a forward movement. Therefore, the target path, which will be further described below, includes forward and backward sections, as is the case, for example, when parallel parking or reversing into a parking space. Figure 2 A control method for automatic reversing in a reverse section according to the present invention is shown, comprising the following steps:

[0078] S1: Establish the linear degree-of-freedom model described above for the vehicle with a trailer;

[0079] S2: Set the towing angle between the trailer and the tractor.

[0080] S3: Given the target path of the trailer;

[0081] S4: Detect the current actual towing angle θ between the trailer and the tractor;

[0082] S5: Compare the actual towing angle θ with the set towing angle Comparison,

[0083] In step S5, if it is determined that the actual towing angle θ reaches or exceeds the set towing angle... Then, step S51 is executed: using the towing angle controller, based on the actual towing angle θ and the set towing angle... To calculate the steering angle δ of the front wheels of the tractor v Otherwise, proceed to step S52: using the turning radius controller based on the actual towing angle θ and the target turning radius r of the trailer. t To calculate the steering angle δ of the front wheels of the tractor v Based on the front wheel steering angle δ v This controls the steering wheel angle of the towing vehicle. By depriving the turning radius controller of control, it is possible to prevent the actual towing angle θ from exceeding a certain range during reversing, thereby avoiding trailer folding.

[0084] Normally, there is a certain relationship between the steering angle of a car's front wheels and the steering wheel angle, especially a proportional relationship. The control system can obtain the steering wheel angle based on the calculated front wheel steering angle, which will not be elaborated further.

[0085] It should be noted that the step names S1, etc., mentioned above (and below) are only used to distinguish between steps and facilitate their reference, and do not represent the order of the steps. The flowcharts in the accompanying figures are merely examples of how this method is executed. Unless there is a clear conflict, the steps can be executed in various orders or simultaneously.

[0086] Set towing angle Based on the extreme towing angle θ max Configure the settings. Instead of obtaining the limiting towing angle θ using an incremental equation for the towing angle, this method will be used. max According to the present invention, the limiting towing angle θ max This is simplified and derived from the inherent parameters of the vehicle with the trailer itself. When the towing angle reaches its limit, the towing angle θ... maxAt this point, the steering wheel angle reaches its maximum, and consequently, the steering angle of the towing vehicle's front wheels reaches its maximum. According to the kinematic equations, at this point, neither forward nor backward movement of the vehicle will cause a change in the towing angle. Therefore, this limiting towing angle θ... max The calculation is performed as follows:

[0087]

[0088] Where, r v This is the minimum turning radius of the rear wheels of the tractor.

[0089] r H This is the minimum turning radius at the hinge point;

[0090] δ vmax This is the maximum steering angle of the front wheels of the tractor.

[0091] exist Figure 3 The control method shown is the same as in Figure 2 The difference in the control methods shown lies in the different conditions upon which the control of the turning radius controller is deprived. According to... Figure 3 When setting the towing angle Less than the limit towing angle θ max Under the premise that it is determined in step S5 that the actual towing angle θ reaches or exceeds the set towing angle Then proceed to step S6: Predict the towing angle between the trailer and the tractor using the turning radius controller. Based on the prediction results, if the towing angle shows an increasing trend, the towing angle controller calculates the tractor's front wheel steering angle δ. v (Step S51); If the towing angle shows a decreasing trend, the steering angle δ of the tractor's front wheels is recalculated by the turning radius controller. v (Step S52). That is, only when the actual towing angle θ is greater than or equal to the set towing angle... Furthermore, control is only initiated by the trailer angle controller when there is an increasing trend. By further restricting the control authority of the trailer angle controller, the trajectory tracking of the trailer can be better achieved while ensuring reversing safety.

[0092] This prediction process can be achieved by using a turning radius controller to calculate the towing angle after the tractor has reversed a certain distance (e.g., 10 centimeters).

[0093] It should be noted that the "target turning radius" refers to the turning radius of the midpoint of the trailer's axle at the next moment (which can also be understood as the midpoint of the trailer's wheel in the kinematic model), and it can also be called the expected turning radius.

[0094] Optionally, the target turning radius r in the reverse segment of the target path tThe determination can be based on pre-aiming and tracking methods, such as... Figure 4 As shown in the figure:

[0095]

[0096] Where s is the offset distance, which is the component of the distance between the midpoint of the trailer's wheel axle and the pre-aiming point on the transverse axis perpendicular to the longitudinal axis.

[0097] d represents the aiming distance, which is the component of the distance between the midpoint of the trailer's wheel axle and the aiming point along the longitudinal axis of the trailer.

[0098] Therefore, in step S52, the turning radius controller determines the target turning radius r. t The front wheel steering angle δ of the tractor is calculated using the actual towing angle θ. v The details are as follows:

[0099]

[0100] In step S51, the towing angle controller is based on the actual towing angle θ and the set towing angle. To calculate the steering angle δ of the front wheels of the tractor v The details are as follows:

[0101]

[0102] Where k is a constant, a proportionality coefficient, representing the response speed of the towing angle between the tractor and the trailer.

[0103] Figure 5 This illustrates a control method for automatic reversing in the forward section, wherein the control method executes step S7, which involves using a trailer angle controller based on the actual trailer angle θ and the target trailer angle θ. t To calculate the steering angle δ of the front wheels of the tractor v Here, the target towing angle θ t This refers to the towing angle at the midpoint of the trailer's wheel axle at the next moment, and can also be called the desired towing angle. The towing angle controller is used only in the forward section primarily because the turning radius controller is unsuitable when the trailer begins to turn. For example, when the trailer begins to turn left, due to its yaw tendency around the vertical z-axis, the turning radius controller will determine that the tractor unit will turn right, which contradicts reality. In the forward section, the trailer follows the tractor unit and maintains the same direction of rotation as the tractor unit (unlike the reverse section, where the tractor unit's direction of rotation is opposite to the trailer's).

[0104] Similarly, the target towing angle θ in the reverse segment of the target path is calculated based on the trailer's pre-aiming tracking.t :

[0105]

[0106] Therefore, in step S7, the towing angle controller bases the target towing angle θ on this... t The steering angle of the tractor's front wheels is calculated using the actual towing angle θ.

[0107]

[0108] It should be noted here that when the calculated target towing angle θ t Greater than the towing angle set above the previously mentioned At that time, let the target be towed at an angle θ t Equivalent to setting the towing angle

[0109] Optionally, the control method according to the invention can also include endpoint detection of the target path. When the target path includes a forward segment and a reverse segment, the endpoint detection involves the intersection of the forward and reverse segments (which can also be referred to as the first endpoint or turnaround point) and the final position of the set midpoint of the trailer axle (which can also be referred to as the second endpoint). However, in the case of a target path that only includes a reverse segment, the endpoint detection can involve only the second endpoint.

[0110] Figure 6 The diagram illustrates the target path for reversing into a parking space. This path consists of multiple straight and curved segments, with the first endpoint denoted by p1 and the second endpoint by p2. Optionally, a circular region can be used for endpoint detection, such as... Figure 6 As shown, the first or second endpoint is located on the circumference of the circular area, and the target path passes through the center of the circular area. After the midpoint of the trailer axle enters the circular area, a warning to change direction or stop is issued when the midpoint of the trailer axle leaves the circular area. The radius of the circular area can be autonomously set according to the required control precision, for example, in the range of 0.5m to 1m, particularly exactly 0.5m.

[0111] Optionally, a high signal is emitted when the midpoint of the trailer axle enters the circular area, and a low signal is emitted in other areas. When the center of the trailer axle leaves the circular area, that is, when triggered by the falling edge of the transition from a high signal to a low signal, a warning to change the driving direction or stop is issued. Compared to point-to-point detection, by setting a larger circular area for detection, more accurate detection of the endpoint can be achieved even when errors occur in trailer trajectory tracking.

[0112] Furthermore, the present invention also includes a control system 100 configured to execute a control method according to any one or more of the foregoing embodiments. For example... Figure 7 As shown, the control system 100 includes a detection module 1 for detecting the actual towing angle between the trailer and the tractor, a comparison module 2 for comparing the detected towing angle with a set towing angle, a towing angle controller 3, and a turning radius controller 4, all interconnected with each other. The towing angle controller 3 calculates the tractor's front wheel steering angle based on the actual towing angle and the set towing angle, while the turning radius controller 4 calculates the tractor's front wheel steering angle based on the actual towing angle and the trailer's target turning radius. This control system can be integrated into the vehicle's ECU.

[0113] It should be understood that all the above embodiments are exemplary and not restrictive, and any modifications or variations made by those skilled in the art to the specific embodiments described above under the concept of the present invention should be within the legal protection scope of the present invention.

Claims

1. A control method for automatic reversing of a vehicle with a trailer, comprising the following steps: S1: Establish a linear two-degree-of-freedom kinematic model of the vehicle with trailer; S2: Set the towing angle between the trailer and the tractor. ; S3: Given the target path of the trailer; S4: Detects the current actual towing angle between the trailer and the tractor. ; Its features are, The control method further includes the following steps: S5: The actual towing angle With the set towing angle A comparison is made in the reverse section of the target path, if the actual towing angle... Reaching or exceeding the set towing angle Then S51: Using the towing angle controller based on the actual towing angle The set towing angle The distance from the center of the trailer axle to the hinge point The distance from the drive wheels to the steering wheels of the tractor The distance from the drive wheel of the tractor to the articulation point To calculate the steering angle of the front wheels of the tractor Otherwise, S52: using the turning radius controller based on the actual towing angle Target turning radius of the trailer The distance from the drive wheels to the steering wheels of the tractor The distance from the drive wheel of the tractor to the articulation point The distance from the center of the trailer axle to the hinge point To calculate the steering angle of the front wheels of the tractor Based on the front wheel steering angle To control the steering wheel angle of the tractor unit.

2. The control method for automatic reversing of a vehicle with a trailer according to claim 1, characterized in that, The set towing angle given in step S2 Less than the maximum towing angle between the tractor and the trailer If the actual towing angle is determined in step S5 Reaching or exceeding the set towing angle Then, proceed to step S6: predict the towing angle between the trailer and the tractor using the turning radius controller. If the towing angle between the trailer and the tractor shows an increasing trend, proceed to step S51. If the towing angle between the trailer and the tractor shows a decreasing trend, proceed to step S52.

3. The control method for automatic reversing of a vehicle with a trailer according to claim 1 or 2, characterized in that, Calculate the target turning radius of the trailer in the reverse section using a pre-aiming and tracking method. : Where s is the offset distance, which is the component of the distance between the midpoint of the trailer's wheel axle and the pre-aiming point on the transverse axis perpendicular to the trailer's longitudinal axis. d represents the aiming distance, which is the component of the distance between the midpoint of the trailer's wheel axle and the aiming point along the longitudinal axis of the trailer.

4. The control method for automatic reversing of a vehicle with a trailer according to claim 3, characterized in that, Steering angle of the front wheels of the tractor in step S52 The calculation method is as follows: 。 5. The control method for automatic reversing of a vehicle with a trailer according to claim 1 or 2, characterized in that, Steering angle of the front wheels of the tractor in step S51 The calculation method is as follows: Where k is a constant.

6. The control method for automatic reversing of a vehicle with a trailer according to claim 1, characterized in that, The target path also includes a forward section, and the control method further includes step S7: during the forward section, the trailer angle controller is based on the actual trailer angle. towing angle with target To calculate the steering angle of the front wheels of the tractor .

7. The control method for automatic reversing of a vehicle with a trailer according to claim 6, characterized in that, The target towing angle of the trailer in the forward section is calculated using the aiming and tracking method. The target towing angle as follows: in, s is the offset distance, which is the component of the distance between the midpoint of the trailer's wheel axle and the pre-aiming point on the transverse axis perpendicular to the trailer's longitudinal axis. d represents the aiming distance, which is the component of the distance between the midpoint of the trailer's wheel axle and the aiming point along the longitudinal axis of the trailer.

8. The control method for automatic reversing of a vehicle with a trailer according to claim 7, characterized in that, Step S7: Steering angle of the tractor's front wheels The calculation method is as follows: Where k is a constant; When the calculated target towing angle Greater than the set towing angle At that time, the target towing angle is set. Equal to the set towing angle .

9. The control method for automatic reversing of a vehicle with a trailer according to claim 2, characterized in that, Limit towing angle between trailer and tractor The calculation method is as follows: in, This is the minimum turning radius of the rear wheels of the tractor. This is the minimum turning radius at the hinge point; This is the maximum steering angle of the front wheels of the tractor.

10. The control method for automatic reversing of a vehicle with a trailer according to claim 1 or 2, characterized in that, The target path has a forward section and a reverse section. The intersection of the forward section and the reverse section is the first endpoint, and the final position of the set midpoint of the trailer wheel axle is the second endpoint. During the automatic reversing process, it is detected whether the midpoint of the trailer wheel axle has reached the first endpoint or the second endpoint. When the first endpoint or the second endpoint is reached, a warning to change the driving direction or stop is issued.

11. The control method for automatic reversing of a vehicle with a trailer according to claim 10, characterized in that, A circular area is used to detect the first or second endpoint, which is located on the circumference of the circular area and the target path passes through the center of the circular area. After the midpoint of the trailer axle enters the circular area, a warning to change the driving direction or stop is issued when the midpoint of the trailer axle leaves the circular area.

12. A control system, characterized in that, The control system is configured to execute the control method for automatic reversing of a trailer vehicle according to any one of claims 1 to 11, and the control systems are communicatively connected to each other. The detection module is used to detect the actual towing angle between the trailer and the tractor. The comparison module is used to compare the detected towing angle with the set towing angle; A towing angle controller is used to calculate the steering angle of the front wheels of the tractor based on the actual towing angle and the set towing angle; A turning radius controller is used to calculate the steering angle of the tractor's front wheels based on the actual towing angle and the target turning radius of the trailer.

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