Automobile parking front wheel automatic straightening system and method

Abstract

The application provides an automatic front wheel alignment system and method for a vehicle, and relates to the technical field of wheel alignment control. The system comprises an IMU sensor, which is installed at the rotation axis center of the front and rear brake discs of the vehicle, and is used for obtaining the pose matrix between the corresponding front and rear wheels; a controller, which is used for receiving the pose matrix between the corresponding front and rear wheels sent by the IMU sensor, and calculating the first deflection angle of the left front wheel relative to the left rear wheel and the second deflection angle of the right front wheel relative to the right rear wheel, and obtaining the average deflection angle based on the first deflection angle and the second deflection angle; and controlling the left front wheel and the right front wheel to steer based on the average deflection angle until the left front wheel and the right front wheel are aligned. When the vehicle is parked, the algorithm is designed to obtain the steering angle difference of the front and rear wheels in real time, and then the steering angle difference is converted into an electric signal to control the operation of the steering motor, so that the high-precision automatic alignment of the front wheels of the vehicle is realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wheel alignment control, and particularly relates to an automatic wheel alignment system and method for a vehicle before parking. BACKGROUND

[0002] When a vehicle is parked, the front wheels need to be aligned to avoid aging of the vehicle steering system. However, in the actual use of the vehicle, many drivers often forget this step due to habit, or deliberately do not align the wheels due to parking technology. Even some drivers do not have the consciousness of automatically aligning the wheels when parking.

[0003] If the wheels are not aligned after parking, it will cause damage to multiple aspects of the vehicle:

[0004] (1) If the wheels are not aligned after parking, it is equivalent to the power pump pushing the oil pump out to drive the steering, and then there is no return of the oil. Negative pressure will be formed in the power pump, accelerating the aging of the power pump, and the pressure on the oil pipe is also too large.

[0005] (2) If the wheels are not aligned after parking, the wheels are parked at an inclined angle, and the weight of the vehicle body is not acting on the front frame, but on the front cross link. If this continues for a long time, the cross link will be deformed, causing inaccurate steering and excessive play, and in severe cases, it can cause accidents due to direction shaking during driving.

[0006] (3) If the wheels are not aligned after parking, in addition to the damage to the above two parts, it will also damage the tires. Under normal circumstances, the tire will maintain the state of the tread being grounded. When the wheels are not aligned, due to the existence of the kingpin inclination angle and the design of the passenger car tire camber, the tire is not completely grounded by the tread, but by the shoulder and part of the tread. In this case, the sidewall pressure of the tire is relatively large. Since the tire sidewall is relatively thin, if the tire is subjected to unbalanced stress frequently, it will accelerate the aging and deformation of the tire sidewall. After the aging and deformation of the tire sidewall, it is likely to cause tire leakage or burst.

[0007] (4) If the wheels are not aligned after parking, the vehicle is likely to deviate when starting again, increasing the probability of traffic accidents.

[0008] The existing vehicle parking wheel alignment method is often to detect the deflection angle of the steering wheel through the steering wheel angle sensor, control the steering wheel to align, and then control the wheels to align. This method often lacks detection of whether the wheels are accurately aligned, and there may be some errors in the alignment.

[0009] In addition, there is also a method for detecting wheel angle signals by using a wheel angle sensor to determine whether the wheels are straightened in the prior art, and when it is detected that the wheels are not straightened, the electric power steering system straightens the wheels according to the wheel angle signals. For example, the technology disclosed in the Chinese patent application file with the publication number CN 102795262 A and the name of the wheel automatic straightening system. The above-mentioned technology does not disclose how to specifically set the wheel angle sensor to detect the wheel angle signal. Since different wheel angle sensors themselves have detection errors, if the wheel angle signals detected by the wheel angle sensors have large errors, the accuracy of the wheel straightening will be directly affected. SUMMARY

[0010] To overcome the above-mentioned deficiencies of the prior art, the present application provides an automobile parking front wheel automatic straightening system and method, which automatically obtains the poses of each wheel by two groups of IMU sensors, installs the two groups of IMU sensors at the rotation shaft centers of the front and rear brake discs, and designs an algorithm to obtain the steering angle difference of the front and rear wheels in real time when the automobile is parked. Then, the steering angle difference is converted into an electric signal to control the operation of the steering motor, thereby realizing high-precision automatic straightening of the front wheels of the vehicle.

[0011] To achieve the above-mentioned purpose, one or more embodiments of the present application provide the following technical solutions:

[0012] The first aspect of the present application provides an automobile parking front wheel automatic straightening system.

[0013] The automobile parking front wheel automatic straightening system comprises an IMU sensor and a controller, wherein:

[0014] The IMU sensor is installed at the rotation shaft center of the front and rear brake discs of the vehicle and is used to obtain the pose matrix between the corresponding front and rear wheels;

[0015] The controller is used to receive the pose matrix between the corresponding front and rear wheels sent by the IMU sensor, calculate the first deflection angle of the left front wheel relative to the left rear wheel and the second deflection angle of the right front wheel relative to the right rear wheel, and obtain the average deflection angle based on the first deflection angle and the second deflection angle.

[0016] Based on the average deflection angle, the left front wheel and the right front wheel are controlled to steer until the left front wheel and the right front wheel are straightened.

[0017] As an optional technical solution, the IMU sensor is provided with two groups, and the two groups of IMU sensors are redundantly designed. When one group of IMU sensors fails, the other group of IMU sensors replaces the failed IMU sensor to realize the pose data acquisition function.

[0018] As an optional technical solution, the IMU sensor is used to establish an IMU coordinate system of the left rear wheel and the right rear wheel, specifically:

[0019] The center positions of the left rear wheel and the right rear wheel are taken as origins, the advancing directions of the left rear wheel and the right rear wheel are taken as positive directions of x axes, and the positive directions of y axes and z axes are determined, to establish IMU coordinate systems of the left rear wheel and the right rear wheel respectively.

[0020] As an alternative technical solution, the IMU sensor is configured to obtain a corresponding pose matrix between the front and rear wheels, the pose matrix between the front and rear wheels including a pose matrix of the left front wheel relative to the left rear wheel and a pose matrix of the right front wheel relative to the right rear wheel, and the specific method is as follows:

[0021] Based on the established IMU coordinate systems of the left rear wheel and the right rear wheel, the rotation angles of the left front wheel relative to the left rear wheel and the right front wheel relative to the right rear wheel in the x, y and z directions are measured respectively after parking;

[0022] The rotation matrices of the left front wheel relative to the left rear wheel and the right front wheel relative to the right rear wheel in the x, y and z directions are calculated respectively;

[0023] The product of the rotation matrices in the x, y and z directions is calculated to obtain the pose matrix of the left front wheel relative to the left rear wheel and the right front wheel relative to the right rear wheel.

[0024] As an alternative technical solution, the rotation angles of the left front wheel relative to the left rear wheel or the right front wheel relative to the right rear wheel in the x, y and z directions are α, β and γ respectively after parking, and the corresponding rotation matrices in the x, y and z directions are as follows:

[0025] Rotation around the x axis:

[0026]

[0027] Rotation around the y axis:

[0028]

[0029] Rotation around the z axis:

[0030]

[0031] In summary, the pose matrix of the left front wheel relative to the left rear wheel or the right front wheel relative to the right rear wheel is

[0032] R xyz is:

[0033] R xyz = R x (α) * R y (β) * R z (γ);

[0034] wherein, R x(α) is the x-direction rotation matrix of the left front wheel relative to the left rear wheel, or the right front wheel relative to the right rear wheel; R y (β) is the y-direction rotation matrix of the left front wheel relative to the left rear wheel, or the right front wheel relative to the right rear wheel; R z (γ) is the z-direction rotation matrix of the left front wheel relative to the left rear wheel, or the right front wheel relative to the right rear wheel.

[0035] As an alternative technical solution, the controller is configured to calculate a first deflection angle of the left front wheel relative to the left rear wheel, and a second deflection angle of the right front wheel relative to the right rear wheel, in particular by:

[0036] obtaining the rotation matrix R xyz of the front wheel relative to the rear wheel, and inversely deriving the rotation angle of the front wheel relative to the rear wheel:

[0037]

[0038] The calculation formula of sy is as follows:

[0039]

[0040] In the above formula, R(i,j) represents the value of the rotation matrix R xyz of the i-th row and the j-th column; i=L or R, representing left or right respectively; α i , β i , γ i represent the first deflection angle of the left front wheel relative to the left rear wheel, and the second deflection angle of the right front wheel relative to the right rear wheel respectively; α, β, γ are the rotation angles in x, y, z directions respectively.

[0041] As an alternative technical solution, the controller is configured to obtain an average deflection angle based on the first deflection angle and the second deflection angle by using the weighted summation method, and the weight values of the first deflection angle and the second deflection angle can be set.

[0042] As an alternative technical solution, a manual switch is further included, which is configured to obtain an activation signal of the automatic front wheel alignment system of the vehicle from a user, and send the activation signal to the controller;

[0043] The controller is further configured to start the automatic front wheel alignment function of the vehicle when receiving the activation signal.

[0044] As an alternative technical solution, the controller is further configured to detect the current state of the vehicle, including detecting whether the engine or electric drive is in working state, whether the driver has left the cab, and whether there is an obstacle in the trajectory envelope of the wheel steering;

[0045] When it is judged that the engine or the electric drive is not in working state, the driver leaves the driver's cabin, and there is no obstacle in the trajectory envelope of the wheel steering, the automatic front wheel alignment function of the vehicle parking is executed.

[0046] The second aspect of the present application provides a method for automatically aligning front wheels of a vehicle during parking.

[0047] The method for automatically aligning front wheels of a vehicle during parking comprises the following steps:

[0048] The IMU sensor obtains the pose matrix between the front and rear wheels;

[0049] The controller receives the pose matrix between the front and rear wheels sent by the IMU sensor, and calculates the first deflection angle of the left front wheel relative to the left rear wheel and the second deflection angle of the right front wheel relative to the right rear wheel, and obtains the average deflection angle based on the first deflection angle and the second deflection angle.

[0050] Then, based on the average deflection angle, the left front wheel and the right front wheel are controlled to steer until the left front wheel and the right front wheel are aligned.

[0051] The above one or more technical solutions have the following beneficial effects:

[0052] The present application provides a system and method for automatically aligning front wheels of a vehicle during parking, which automatically obtains the pose of each wheel by two groups of IMU sensors, installs the two groups of IMU sensors at the center of the rotating shaft of the front and rear brake discs, and when the vehicle is parked, designs an algorithm to obtain the steering angle difference of the front and rear wheels in real time, and then converts the steering angle difference into an electrical signal to control the operation of the steering motor, thereby realizing high-precision automatic alignment of the front wheels of the vehicle.

[0053] In the present application, two groups of IMU sensors are used to obtain the pose data of the left front wheel and the left rear wheel, and the pose data of the right front wheel and the right rear wheel, respectively, the IMU coordinate systems of the left rear wheel, the right rear wheel, the left front wheel and the right front wheel are established, and the rotation matrix between the left rear wheel and the left front wheel and the rotation matrix between the right rear wheel and the right front wheel are calculated, and then the first deflection angle of the left front wheel relative to the left rear wheel and the second deflection angle of the right front wheel relative to the right rear wheel are calculated, and the average deflection angle is obtained based on the first deflection angle and the second deflection angle, and the average deflection angle obtained in this way is more accurate, thereby improving the accuracy of wheel alignment.

[0054] The controller of the application detects the current state of the automobile before performing the automatic wheel alignment function, including detecting whether the engine or electric drive is in working state, whether the driver leaves the driver's cabin, and whether there is an obstacle in the trajectory envelope of the wheel steering; when the engine or electric drive is not in working state, the driver leaves the driver's cabin, and there is no obstacle in the trajectory envelope of the wheel steering, the automatic wheel alignment function of the automobile before parking is performed, which improves the safety of vehicle control.

[0055] Advantages of the additional aspects of the application will be in part apparent from the following description, be in part apparent from the following description, or be learned from practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0056] The accompanying drawings, which form a part of this specification, are included to provide a further understanding of the application, and are incorporated by reference herein. The embodiments illustrated in the drawings are presented by way of example in which similar elements are numbered with similar reference numerals, and wherein:

[0057] Figure 1 The first embodiment method flow chart.

[0058] Figure 2 The first embodiment front wheel deflection angle coordinate axis definition chart. DETAILED DESCRIPTION

[0059] It should be noted that the following detailed description is merely exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0060] It is to be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the application.

[0061] In the case of no conflict, the embodiments in the application and the features in the embodiments can be combined with each other.

[0062] Embodiment one

[0063] The embodiment discloses an automobile parking front wheel automatic alignment system.

[0064] As shown in Figure 1 The automobile parking front wheel automatic alignment system comprises an IMU sensor and a controller.

[0065] The IMU sensor is installed at the center of the rotation shaft of the front and rear brake discs, and is used to obtain the pose matrix between the corresponding front and rear wheels.

[0066] a controller configured to receive the pose matrix between the corresponding front and rear wheels sent by the IMU sensor, and calculate a first deflection angle of the left front wheel relative to the left rear wheel and a second deflection angle of the right front wheel relative to the right rear wheel, and obtain an average deflection angle based on the first deflection angle and the second deflection angle;

[0067] based on the average deflection angle, control the left front wheel and the right front wheel to steer until the left front wheel and the right front wheel are straightened.

[0068] In some embodiments, the IMU sensor is provided with two groups, and the two groups of IMU sensors are designed in redundancy, when one group of IMU sensors fails, the other group of IMU sensors replaces the failed IMU sensor to realize the pose data acquisition function.

[0069] In some embodiments, the IMU sensor is used to establish the IMU coordinate system of the left rear wheel and the right rear wheel, specifically:

[0070] The IMU coordinate system of the left rear wheel and the right rear wheel is established with the center position of the left rear wheel and the right rear wheel as the origin, and the forward direction of the left rear wheel and the right rear wheel as the positive direction of the x-axis, and the positive direction of the y-axis and the positive direction of the z-axis are determined.

[0071] In some embodiments, the IMU sensor is used to obtain the corresponding pose matrix between the front and rear wheels, which includes the pose matrix of the left front wheel relative to the left rear wheel and the pose matrix of the right front wheel relative to the right rear wheel, and the specific method is:

[0072] Based on the established IMU coordinate system of the left rear wheel and the right rear wheel, the rotation angles of the left front wheel relative to the left rear wheel and the right front wheel relative to the right rear wheel in the xyz three directions are measured respectively after parking;

[0073] The rotation matrix of the left front wheel relative to the left rear wheel and the rotation matrix of the right front wheel relative to the right rear wheel in the xyz three directions are calculated respectively;

[0074] The product of the corresponding rotation matrix in the xyz three directions is calculated to obtain the pose matrix of the left front wheel relative to the left rear wheel and the pose matrix of the right front wheel relative to the right rear wheel.

[0075] In some embodiments, assuming that the rotation angles of the left front wheel relative to the left rear wheel or the right front wheel relative to the right rear wheel in the x, y, z three directions are α, β, γ respectively, the corresponding rotation matrix in the xyz three directions is:

[0076] Rotation around the x-axis:

[0077]

[0078] Rotation around the y-axis:

[0079]

[0080] Rotation around z-axis:

[0081]

[0082] In summary, the pose matrix of the left front wheel relative to the left rear wheel, or the right front wheel relative to the right rear wheel is

[0083] R xyz is:

[0084] R xyz = R x (α) * R y (β) * R z (γ);

[0085] wherein, R x (α) is the x-direction rotation matrix of the left front wheel relative to the left rear wheel, or the right front wheel relative to the right rear wheel; R y (β) is the y-direction rotation matrix of the left front wheel relative to the left rear wheel, or the right front wheel relative to the right rear wheel; R z (γ) is the z-direction rotation matrix of the left front wheel relative to the left rear wheel, or the right front wheel relative to the right rear wheel.

[0086] In some embodiments, the controller is configured to calculate a first deflection angle of the left front wheel relative to the left rear wheel, and a second deflection angle of the right front wheel relative to the right rear wheel, by:

[0087] obtaining the rotation matrix R xyz of the front wheel relative to the rear wheel, and inversely deriving the rotation angle of the front wheel relative to the rear wheel:

[0088]

[0089] The calculation formula of sy is as follows:

[0090]

[0091] In the above formula, R(i,j) represents the value of the rotation matrix R xyz in the ith row and jth column; i=L or R, representing left or right respectively; α i , β i , γ i represent the first deflection angle of the left front wheel relative to the left rear wheel, and the second deflection angle of the right front wheel relative to the right rear wheel respectively; α, β, γ are the rotation angles in x, y, z directions respectively.

[0092] In some embodiments, the controller is configured to obtain an average deflection angle by using a weighted summation method based on the first deflection angle and the second deflection angle; the weight values of the first deflection angle and the second deflection angle can be set.

[0093] In some embodiments, a manual switch is further included for obtaining an activation signal of the automobile parking front wheel automatic straightening system from a user and sending to the controller.

[0094] The controller is further configured to start the automobile parking front wheel automatic straightening function when the activation signal is received.

[0095] In some embodiments, the controller is further configured to detect the current state of the automobile, including detecting whether the engine or electric drive is in working state, whether the driver has left the driver's cabin, and whether there is an obstacle in the trajectory envelope of the wheel steering.

[0096] When it is determined that the engine or electric drive is not in working state, the driver has left the driver's cabin, and there is no obstacle in the trajectory envelope of the wheel steering, the automobile parking front wheel automatic straightening function is executed.

[0097] The technical solutions of the embodiments will be described in detail below with reference to the accompanying drawings.

[0098] The embodiment provides a wheel automatic straightening method, which automatically obtains the poses of each wheel through two groups of IMU sensors, and the sensors are installed at the rotation shaft centers of front and rear brake discs. When the automobile is parked, the real-time high-precision front and rear wheel steering angle difference is obtained, which is then converted into an electric signal to control the steering motor to run and realize the automatic straightening function of the front wheel of the automobile. The implementation principle diagram is shown in Figure 1 .

[0099] (1) Start or stop the automatic straightening function:

[0100] The manual switch is provided on the automobile, and the driver needs to manually activate the function if the driver needs to use the device.

[0101] Therefore, in the embodiment, the manual switch is configured to obtain an activation signal of the automobile parking front wheel automatic straightening system from a user and send to the controller.

[0102] The controller is configured to start the automobile parking front wheel automatic straightening function when the activation signal is received.

[0103] (2) Detect the current state of the automobile:

[0104] After the function is started, the controller will obtain the running state of the current automobile at regular time intervals. The device will not be started in the following three running states, which are:

[0105] 1. The engine or electric drive is in working state;

[0106] 2. The driver has not left the driver's cabin, and the driver may have other operations at this time, so as to avoid affecting the normal driving of the driver;

[0107] 3. There are obstacles in the trajectory envelope of the wheel steering, and forced steering will damage the tire and the steering device. In the above three states, the device is in the DISENABLE state, and the device does not intervene.

[0108] The present application executes the automatic front wheel alignment function of the car when the engine or the electric drive is not in working state, the driver leaves the driver's room, and there is no obstacle in the trajectory envelope of the wheel steering, which improves the safety of vehicle control.

[0109] (3) Obtain the poses of the front and rear wheels:

[0110] After the device is started, the IMU installed on the brake disc of the car collects the pose data of the front and rear wheels at a frequency of 60HZ (the sampling parameter can be set by the user);

[0111] The IMU coordinate system of the rear wheel is set as O L / R (L represents the left side, and R represents the right side), and the IMU coordinate system of the front wheel is A L / R , as shown in the figure. Figure 2

[0112] Then, the rotation matrix of the front and rear wheels is calculated Specifically, the rotation matrix between the left rear wheel and the left front wheel, and the rotation matrix between the right rear wheel and the right front wheel are calculated. The specific method is:

[0113] The rotation matrix calculation methods of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel are consistent and have no difference. Assuming that the rotation angles of a certain tire in the x, y, and z directions after parking are α, β, and γ respectively, the corresponding rotation matrixes are shown in the following formulas. The rotation matrix is calculated by the IMU sensor and is determined by the characteristics of the IMU itself, and does not need to be programmed and calculated separately.

[0114] Rotation around the x-axis:

[0115]

[0116] Rotation around the y-axis:

[0117]

[0118] Rotation around the z-axis:

[0119]

[0120] Based on the above, the pose matrix of the front wheel relative to the rear wheel is:

[0121] R xyz = R x (α)*R y (β)*R z (γ)​

[0122] After the rotation matrix between the left rear wheel and the left front wheel and the rotation matrix between the right rear wheel and the right front wheel are obtained, the rotation angle β of the front wheel Y axis relative to the rear wheel is calculated i (i = 1, 2, respectively, the angle difference of the left and right sides), respectively, the first deflection angle of the left front wheel relative to the left rear wheel and the second deflection angle of the right front wheel relative to the right rear wheel, the specific method is:

[0123] After the car is parked, the rear wheel of the car will not be deflected relative to the vehicle body, and the steering of the rear wheel can be set as the reference coordinate system. When the rotation matrix R xyz of the first front wheel relative to the rear wheel is obtained, the rotation angle of the front wheel relative to the rear wheel can be inversely deduced, that is:

[0124]

[0125] Where i = L, R represents the first deflection angle and the second deflection angle of the left side and the right side, and sy is calculated as follows:

[0126]

[0127] In the above formula, R(i, j) represents the value of the rotation matrix R xyz of the first front wheel relative to the rear wheel in the i-th row and the j-th column.

[0128] In Figure 2 , β L and β R represent the first deflection angle of the left front wheel relative to the left rear wheel and the second deflection angle of the right front wheel relative to the right rear wheel, respectively.

[0129] Finally, the weighted average β of the two sets of deflection angles mentioned above, that is, the average deflection angle, is calculated. Based on the average deflection angle, the left front wheel and the right front wheel are controlled to steer until the left front wheel and the right front wheel are straightened.

[0130] In this embodiment, in order to improve the effectiveness of the overall system, the two groups of IMU groups designed can also be used as a kind of redundant design. When one of the sensors fails, the remaining sensor group can still work.

[0131] (4) After obtaining the deflection angle of the front wheel relative to the rear wheel, the angle signal is converted into the control signal of the steering motor through the controller. This control system is a negative feedback control, that is, the greater the deflection angle of the front and rear wheels, the more intense the controller controls the steering motor.

[0132] When the deviation angle of the front and rear wheels of the automobile is within the set error range, the control system stops running, avoiding the steering motor being in a working state all the time due to the signal error of the sensor, causing the front wheel to shake. After the front wheel steering position is consistent with the rear wheel, a complete wheel self-aligning process is completed, and the system is turned off.

[0133] Embodiment two

[0134] The embodiment discloses an automatic front wheel aligning method for automobile parking.

[0135] The automatic front wheel aligning method for automobile parking comprises the following steps:

[0136] The IMU sensor obtains the pose matrix between the corresponding front and rear wheels;

[0137] The controller receives the pose matrix between the corresponding front and rear wheels sent by the IMU sensor, and calculates the first deflection angle of the left front wheel relative to the left rear wheel and the second deflection angle of the right front wheel relative to the right rear wheel, and obtains the average deflection angle based on the first deflection angle and the second deflection angle.

[0138] Then, based on the average deflection angle, the left front wheel and the right front wheel are controlled to steer until the left front wheel and the right front wheel are aligned.

[0139] Although the specific embodiments of the present application are described above with reference to the drawings, the description is not a limitation on the scope of protection of the present application, and those skilled in the art should understand that various modifications or changes made on the basis of the technical solutions of the present application without creative labor are still within the scope of protection of the present application.

Claims

1. An automatic front wheel straightening system for a vehicle, characterized in that, The application relates to an automatic front wheel alignment system for a vehicle, comprising an IMU sensor and a controller, wherein: The IMU sensor is installed at the rotation axis center of the front and rear brake discs of the vehicle and is used for acquiring the pose matrix between the corresponding front and rear wheels; The controller is used for receiving the pose matrix between the corresponding front and rear wheels sent by the IMU sensor, calculating the first deflection angle of the left front wheel relative to the left rear wheel and the second deflection angle of the right front wheel relative to the right rear wheel, and obtaining the average deflection angle based on the first deflection angle and the second deflection angle; Based on the average deflection angle, the left front wheel and the right front wheel are controlled to steer until the left front wheel and the right front wheel are aligned; The controller is used for obtaining the average deflection angle by using a weighted summation method based on the first deflection angle and the second deflection angle; and the weight values of the first deflection angle and the second deflection angle can be set.

2. The automobile parking front wheel automatic straightening system according to claim 1, wherein, The IMU sensor is provided with two groups, and the two groups of IMU sensors are designed in a redundant mode; when one group of IMU sensors fails, the other group of IMU sensors replaces the failed IMU sensors to realize the pose data acquisition function.

3. The automobile parking front wheel automatic straightening system according to claim 1, wherein The IMU sensor is used for establishing the IMU coordinate system of the left and right rear wheels, and the specific method is as follows: The IMU coordinate system of the left and right rear wheels is established by taking the center positions of the left and right rear wheels as origins, taking the forward directions of the left and right rear wheels as positive directions of x axes, and simultaneously determining positive directions of y axes and z axes.

4. The automobile parking front wheel automatic straightening system according to claim 3, wherein The IMU sensor is used for acquiring the pose matrix between the corresponding front and rear wheels, and the pose matrix between the corresponding front and rear wheels comprises the pose matrix of the left front wheel relative to the left rear wheel and the pose matrix of the right front wheel relative to the right rear wheel, and the specific method is as follows: Based on the established IMU coordinate system of the left and right rear wheels, the rotation angles of the left front wheel relative to the left rear wheel and the right front wheel relative to the right rear wheel in the x, y and z directions are measured respectively after parking; The rotation matrices of the left front wheel relative to the left rear wheel and the right front wheel relative to the right rear wheel in the x, y and z directions are calculated respectively; The product of the rotation matrices in the x, y and z directions is calculated to obtain the pose matrix of the left front wheel relative to the left rear wheel and the pose matrix of the right front wheel relative to the right rear wheel.

5. The automobile parking front wheel automatic straightening system according to claim 4, wherein Supposing that the rotation angles of the left front wheel relative to the left rear wheel and the right front wheel relative to the right rear wheel in the x, y and z directions are alpha, beta and gamma respectively, the rotation matrices in the x, y and z directions are as follows: Rotation around the x axis: ； Rotation around the y axis: ； Rotation around the z axis: ； In summary, the pose matrix of the left front wheel with respect to the left rear wheel, or the right front wheel with respect to the right rear wheel is: ； wherein, is a x-direction rotation matrix of the left front wheel with respect to the left rear wheel, or the right front wheel with respect to the right rear wheel; is a y-direction rotation matrix of the left front wheel with respect to the left rear wheel, or the right front wheel with respect to the right rear wheel; is a z-direction rotation matrix of the left front wheel with respect to the left rear wheel, or the right front wheel with respect to the right rear wheel.

6. The automobile parking wheel automatic straightening system according to claim 5, wherein The controller is used for calculating the first deflection angle of the left front wheel relative to the left rear wheel and the second deflection angle of the right front wheel relative to the right rear wheel, and the specific method is as follows: obtaining a rotation matrix of the front wheel relative to the rear wheel , the rotation angle of the front wheel relative to the rear wheel is obtained by back calculation ； The calculation formula of sy is as follows: ； In the above equation, R(i,j) represents a rotation matrix the value of the jth column in the ith row; i = L or R, respectively, indicating left or right; 、 、 respectively, represent a first deflection angle of the left front wheel with respect to the left rear wheel, and a second deflection angle of the right front wheel with respect to the right rear wheel; and α, β, γ are rotation angles in x, y, z directions, respectively.

7. The automobile parking wheel automatic straightening system according to claim 1, wherein The application further comprises a manual switch which is used for acquiring the activation signal of the automatic front wheel alignment system of the vehicle sent by a user and sending the activation signal to the controller; The controller is further used for starting the automatic front wheel alignment function of the vehicle when the activation signal is received.

8. The automobile parking wheel automatic straightening system according to claim 1, wherein, The controller is further used for detecting the current state of the vehicle, including detecting whether the engine or the electric drive is in a working state, whether the driver leaves the cab, and whether there is an obstacle in the trajectory envelope of the wheel steering. When it is judged that the engine or the electric drive is not in working state, the driver leaves the driver's cabin, and there is no obstacle in the trajectory envelope of the wheel steering, the automatic front wheel alignment function of the vehicle is executed.

9. A method for automatically straightening the front wheels of a vehicle during parking, characterized in that, The method comprises the following steps: The IMU sensor obtains a pose matrix between the front and rear wheels; The controller receives the pose matrix between the front and rear wheels sent by the IMU sensor, calculates a first deflection angle of the left front wheel relative to the left rear wheel and a second deflection angle of the right front wheel relative to the right rear wheel, and obtains an average deflection angle based on the first deflection angle and the second deflection angle; Then, based on the average deflection angle, the left front wheel and the right front wheel are controlled to steer until the left front wheel and the right front wheel are aligned. The controller is configured to obtain the average deflection angle by using a weighted summation method based on the first deflection angle and the second deflection angle; and the weight values of the first deflection angle and the second deflection angle can be set.

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