A kind of intelligent control system suitable for trailer active steering

Abstract

The application discloses a kind of suitable for trailer active steering intelligent control system, including trailer driving data acquisition unit, trailer roll yaw posture degree resolving unit, trailer coordinate conversion unit, trailer active steering angle resolving unit, trailer steering evaluation unit, trailer steering adjustment unit, trailer steering control execution unit.According to the current trailer driving roll yaw posture degree of posture degree resolving function, introduce trailer steering evaluation factor ρ, and the reasonable range of trailer intermediate shaft active steering angle under the current trailer roll yaw posture degree is obtained.Simultaneously with trajectory coordinate offset and other optimization index control quantity, design trailer active steering angle optimization index constructs trailer active steering angle optimization function, and the active steering angle of each axle of trailer is further obtained by angle relationship.According to the current trailer driving in different roll yaw posture degree, introduce control proportion coefficient matrix, and the active steering boost of trailer is adjusted by solving boost control execution function.

Description

Technical Field

[0001] This invention relates to an intelligent control system for active steering of trailers. Background Technology

[0002] With the increasing sophistication of modern intelligent vehicles, the steering field has gained growing attention, and intelligent power steering has become a key research area. Trailers are crucial for vehicle transportation, and their steering is an indispensable aspect. In recent years, with commercial development, the intelligence of transport vehicles such as trailers has received widespread attention, and active trailer steering has become increasingly popular in the industry, representing the future direction of trailer steering technology.

[0003] However, for the stability of trailer driving and the safety of steering, the adjustment of the trailer's active steering angle and steering assist needs to consider the current trailer's roll and yaw attitude, steering evaluation factors, and adjustment ratio coefficient. Therefore, how to effectively ensure the safety of trailer driving and steering and evaluate the current trailer driving attitude to adjust the steering assist has become a technical problem that the applicant urgently needs to solve. To improve these problems, this invention proposes an intelligent control system for active steering of trailers. Summary of the Invention

[0004] The purpose of this invention is to provide an intelligent control system for active steering of trailers to solve the problems encountered in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an intelligent control system for active steering of trailers, comprising a trailer driving data acquisition unit, a trailer tilt and yaw attitude calculation unit, a trailer coordinate transformation unit, a trailer active steering angle calculation unit, a trailer steering evaluation unit, a trailer steering adjustment unit, and a trailer steering control execution unit.

[0006] The trailer travel data acquisition unit includes a displacement coordinate storage unit for storing the trajectory coordinates of the tractor, a trailer travel side slip angle sensor for acquiring the trailer travel side slip angle β, a trailer travel side tilt angle sensor for acquiring the trailer travel side tilt angle φ, and a trailer travel yaw rate sensor for acquiring the trailer travel yaw rate. The trailer lateral acceleration sensor is used to obtain the trailer lateral acceleration a. y The wheel resistance sensor is used to detect the friction coefficient μ between the road surface and the tire; based on the collected data required for calculating the attitude angle, it is provided to the vehicle driving attitude angle calculation unit.

[0007] The trailer tilt and yaw attitude calculation unit includes a trailer attitude calculation function, designs trailer tilt attitude calculation factor θ1 and trailer yaw attitude calculation factor θ2, and calculates the current trailer driving attitude based on the data information collected by the sensors in the trailer driving data acquisition unit using the trailer attitude calculation function.

[0008] The trailer attitude calculation function is shown in the following formula:

[0009]

[0010] Where Tc is the trailer roll and yaw attitude, τ1 is the sideslip angle correction factor, τ2 is the roll weighting factor, τ3 is the yaw weighting factor, β is the trailer travel sideslip angle, tc1 is the trailer roll attitude, and tc2 is the trailer yaw attitude.

[0011] The trailer coordinate transformation unit converts the coordinate system of the tractor's front axle center to the trailer's coordinate system. By analyzing and calculating the coordinates of the trailer's own rear axle center, the trajectory coordinate offset e can be obtained. s ;

[0012] The trailer active steering angle calculation unit uses the trajectory coordinate offset, trailer lateral acceleration, and trailer intermediate axle active steering angle as optimization index control quantities to construct a trailer active steering angle optimization function, and obtains the active steering angle of each axle of the trailer using the steering angle distribution relationship:

[0013]

[0014] Among them, J t To optimize the active steering angle of the trailer, a y e represents the lateral acceleration of the trailer. s δ is the trajectory coordinate offset. m The active steering angle of the trailer's intermediate axle is denoted by χ1, where χ1 is the weighted control coefficient for the trailer's lateral acceleration, χ2 is the weighted control coefficient for the trajectory coordinate offset, and χ3 is the weighted control coefficient for the trailer's rear axle steering angle. The trailer steering evaluation unit needs to differentiate the attitude threshold based on the trailer roll and yaw attitude Tc value calculated by the trailer roll and yaw attitude calculation unit, introducing a trailer steering evaluation factor ρ to calculate the reasonable range δ of the active steering angle of the trailer's intermediate axle under the current trailer roll and yaw attitude. m * (If the trailer's yaw attitude value Tc is 0.85 < Tc < 1 at this time, it is determined that the trailer is currently in a high yaw attitude):

[0015]

[0016] Where, ρ minρ represents the minimum value within the range of the trailer steering evaluation factor ρ. max The maximum value of the trailer steering evaluation factor ρ is given within its range, Tc is the current trailer roll and yaw attitude, and δ is the maximum value of the trailer steering evaluation factor ρ within its range. m * min δ is the minimum reasonable range of active steering angle for the intermediate axle of the trailer. m * max δ represents the maximum value within the reasonable range of the active steering angle of the trailer's intermediate axle. m * min ≤δ m * ≤δ m * max ;

[0017] The trailer steering adjustment unit adjusts the active steering assist of the trailer according to different trailer tilt and yaw attitudes. It introduces a lateral control proportional coefficient matrix ε and a longitudinal control proportional coefficient matrix ∈. The control proportional coefficient matrix is ​​calculated based on the trailer's current tilt and yaw attitude and transmitted to the trailer steering control execution unit.

[0018] The trailer steering control execution unit designs a power assist control execution function based on the calculated lateral control ratio coefficient matrix and longitudinal control ratio coefficient matrix, thereby controlling the active steering assist of the trailer.

[0019] The trailer roll and yaw attitude calculation unit needs to use the designed trailer roll attitude calculation factor θ1 and trailer yaw attitude calculation factor θ2 to perform preliminary calculations to obtain trailer roll attitude tc1 and trailer yaw attitude tc2.

[0020] Based on the trailer roll angle φ collected by the trailer roll angle sensor in the trailer travel data acquisition unit, there is a trailer roll attitude solution factor θ1. The range of θ1 is limited to 0.5 < θ1 < 1. It is positively correlated with the degree of trailer roll. The larger the roll angle, the larger the value of the roll attitude solution factor θ1, and vice versa.

[0021] Based on the preliminary calculation method for the trailer roll attitude, a corresponding trailer roll attitude calculation factor θ1 is assigned to the trailer roll angle φ, and the roll attitude tc1 is calculated.

[0022]

[0023] Where φ is the trailer roll angle and θ1 is the trailer roll attitude factor;

[0024] Based on the trailer travel data collected by the trailer travel yaw rate sensor in the trailer travel data acquisition unit...

[0025] yaw rate There is a trailer yaw attitude solution factor θ2, the range of which is limited to 0 < θ2 < 0.85. It is positively correlated with the degree of yaw of the trailer. The larger the yaw angle, the larger the value of the yaw attitude solution factor θ2, and vice versa.

[0026] Based on the preliminary calculation method for yaw attitude, a corresponding trailer yaw attitude calculation factor θ2 is assigned to the trailer yaw angle φ, and the trailer yaw attitude tc2 is calculated.

[0027]

[0028] Where φ is the trailer yaw angle, which is determined by the trailer yaw rate. Points can be obtained θ2 is the factor for calculating the trailer yaw attitude.

[0029] The trailer attitude calculation function, after completing the initial calculation of the trailer roll attitude tc1 and trailer yaw attitude tc2, assigns a roll angle correction factor τ1, a roll weighting factor τ2, and a yaw weighting factor τ3 to the trailer travel sideslip angle, trailer roll attitude, and trailer yaw attitude, respectively, as follows:

[0030]

[0031] Where Tc is the trailer roll and yaw attitude, τ1 is the sideslip angle correction factor, τ2 is the roll weighting factor, τ3 is the yaw weighting factor, β is the trailer travel sideslip angle, tc1 is the trailer roll attitude, and tc2 is the trailer yaw attitude.

[0032] The trailer coordinate transformation unit analyzes and calculates the tractor trajectory coordinates stored in the displacement coordinate storage device. The tractor front axle center trajectory stored in the displacement coordinate storage device is as follows:

[0033]

[0034] Where X is the trajectory of the center of the front axle of the tractor along the X-axis, Y is the trajectory of the center of the front axle of the tractor along the Y-axis, and x1(n) and y1(n) are the instantaneous coordinates of different coordinate points at the center of the front axle of the tractor along the X and Y axes.

[0035] Instantaneous coordinates of the trailer's intermediate axle center along the X and Y axes during travel:

[0036]

[0037] Where x2(n) and y2(n) are the instantaneous coordinates of different coordinate points traveling at the center of the intermediate axle of the trailer along the X and Y axes, L1 is the center distance of the front axle of the tractor, L2 is the center distance of the rear axle of the trailer, v is the longitudinal speed of the trailer, φ is the yaw angle of the trailer, β is the side slip angle of the trailer, and φ is the side tilt angle of the trailer.

[0038] The coordinate transformation unit is used to convert the coordinate system of the tractor's front axle center to the coordinate system of the trailer:

[0039]

[0040] Among them, X 12 (n) represents the instantaneous coordinates of the tractor's front axle center, converted from the coordinate system to the trailer coordinate system along the X-axis, where Y... 12 (n) represents the instantaneous coordinates of the center of the front axle of the tractor converted from the coordinate system to the coordinate system of the trailer along the Y-axis, L1 is the center distance of the front axle of the tractor, L2 is the center distance of the rear axle of the trailer, φ is the yaw angle of the trailer, and β is the side slip angle of the trailer.

[0041] The trailer active steering angle calculation unit will calculate the offset based on the coordinates in the coordinate system transformed by the trailer coordinate transformation unit, and then calculate the trailer active steering angle:

[0042] At this point, the trajectory coordinate offset e can be obtained by calculating the trajectory coordinates between the rear axle center of the trailer and the front axle center of the tractor after conversion. s :

[0043]

[0044] Among them, e s Y is the trajectory coordinate offset. 12 (i+1) represents the instantaneous coordinates of the tractor's front axle center along the Y-axis, converted from the tractor's coordinate system to the trailer's coordinate system. 12 (i) represents the instantaneous coordinates of the center of the front axle of the tractor vehicle along the Y-axis direction, converted from the coordinate system of the tractor vehicle's coordinate point (i) to the trailer coordinate system. 12 (i+1) represents the instantaneous coordinates of the tractor's front axle center along the X-axis, converted from the tractor's coordinate system to the trailer's coordinate system. 12 (i) represents the instantaneous coordinates of the center of the front axle of the tractor vehicle along the X-axis direction at coordinate point (i) in the tractor vehicle coordinate system converted to the trailer coordinate system.

[0045] Using trajectory coordinate offset, trailer lateral acceleration, and trailer intermediate axle active steering angle as optimization control parameters, an optimization index for trailer active steering angle is designed. Weighted control coefficients are assigned to each optimization control parameter, and an optimization function for trailer active steering angle is constructed.

[0046]

[0047] Among them, J t To optimize the active steering angle of the trailer, a y e represents the lateral acceleration of the trailer. s δ is the trajectory coordinate offset. m χ1 is the weighted control coefficient of the trailer's lateral acceleration, χ2 is the weighted control coefficient of the trajectory coordinate offset, and χ3 is the weighted control coefficient of the trailer's intermediate axle's active steering angle.

[0048] By determining the values ​​of the weight control coefficients, the optimization index J of the trailer's active steering angle is calculated. t :

[0049]

[0050] Among them, J t The active steering angle optimization index for trailers is defined as follows: τ1 is the slip angle correction factor, τ2 is the roll weighting factor, τ3 is the yaw weighting factor, tc1 is the trailer roll attitude, tc2 is the trailer yaw attitude, χ1 is the weight control coefficient of trailer lateral acceleration, χ2 is the weight control coefficient of trajectory coordinate offset, and χ3 is the weight control coefficient of trailer intermediate axle steering angle.

[0051] The control quantity, the active steering angle δ of the trailer intermediate axle, is obtained by solving the optimization function of the trailer's active steering angle. m To ensure that the lateral forces on each axle of the trailer are equal and to distribute the trailer's turning angles taking into account the turning angle relationships of each axle:

[0052]

[0053] Where, δ f For the active steering angle of the trailer's front axle, δ m δ is the active steering angle of the intermediate axle of the trailer. r L3 is the active steering angle of the trailer's rear axle, L4 is the axle spacing of the trailer, and v is the longitudinal speed of the trailer. This represents the yaw rate of the trailer.

[0054] The trailer steering evaluation unit needs to distinguish the attitude threshold based on the trailer tilt and yaw attitude Tc value calculated by the trailer tilt and yaw attitude calculation unit. Under the condition that the vehicle does not have an accident, the size range of the trailer tilt and yaw attitude Tc is 0 < Tc < 1. The larger the calculated Tc value, the greater the tilt and yaw attitude of the trailer, that is, the trailer driving attitude is unstable and prone to accidents such as rollover and fishtailing. Conversely, the smaller the calculated Tc value, the smaller the tilt and yaw attitude of the trailer, and the better the trailer driving stability.

[0055] A trailer steering evaluation factor ρ is introduced, with a limit of 0.3 ≤ ρ ≤ 1. Within this range, the trailer steering evaluation factor ρ serves as the control index for safe trailer steering, meaning that the intermediate axle steering angle calculated by the trailer active steering angle calculation unit must be within the reasonable range δ of the trailer intermediate axle active steering angle under the current roll and yaw attitude. m * Inside;

[0056] If the trailer roll and yaw attitude value Tc is 0.85 < Tc < 1, then the trailer is determined to be in a high roll and yaw attitude. Using the trailer roll and yaw attitude calculation unit to calculate the trailer roll and yaw attitude value Tc and the trailer steering evaluation factor ρ, the reasonable range δ of the active steering angle of the trailer's intermediate axle under the current trailer roll and yaw attitude is calculated. m * :

[0057]

[0058] Where, ρ min ρ represents the minimum value within the range of the trailer steering evaluation factor ρ. max The maximum value of the trailer steering evaluation factor ρ is given within its range, Tc is the current trailer roll and yaw attitude, and δ is the maximum value of the trailer steering evaluation factor ρ within its range. m * min δ is the minimum reasonable range of active steering angle for the intermediate axle of the trailer. m * max δ represents the maximum value within the reasonable range of the active steering angle of the trailer's intermediate axle. m * min ≤δ m * ≤δ m * max ;

[0059] If the trailer roll and yaw attitude value Tc is 0.55 < Tc < 0.85 at this time, it is determined that the trailer is currently in a medium roll and yaw attitude. Using the trailer roll and yaw attitude calculation unit to calculate the trailer roll and yaw attitude value Tc and the trailer steering evaluation factor ρ, the reasonable range δ of the active steering angle of the trailer's intermediate axle under the current trailer roll and yaw attitude is calculated. m * :

[0060]

[0061] Where, ρ min ρ represents the minimum value within the range of the trailer steering evaluation factor ρ.max The maximum value of the trailer steering evaluation factor ρ is given within its range, Tc is the current trailer roll and yaw attitude, and δ is the maximum value of the trailer steering evaluation factor ρ within its range. m * min δ is the minimum reasonable range of active steering angle for the intermediate axle of the trailer. m * max δ represents the maximum value within the reasonable range of the active steering angle of the trailer's intermediate axle. m * min ≤δ m * ≤δ m * max ;

[0062] If the trailer roll and yaw attitude value Tc is 0 < Tc < 0.55, then the trailer is determined to be in a low roll and yaw attitude. Using the trailer roll and yaw attitude calculation unit to calculate the trailer roll and yaw attitude value Tc and the trailer steering evaluation factor ρ, the reasonable range δ of the active steering angle of the trailer's intermediate axle under the current trailer roll and yaw attitude is calculated. m * :

[0063]

[0064] Where, ρ min ρ represents the minimum value within the range of the trailer steering evaluation factor ρ. max For trailer steering assessment

[0065] The maximum value of ρ within its range, Tc is the current trailer roll and yaw attitude, and δ m * min δ is the minimum reasonable range of active steering angle for the intermediate axle of the trailer. m * max δ represents the maximum value within the reasonable range of the active steering angle of the trailer's intermediate axle. m * min ≤δ m * ≤δ m * max .

[0066] The trailer steering adjustment unit adjusts the active steering assist of the trailer according to different trailer tilt and yaw attitudes. It introduces a lateral control proportional coefficient matrix ε and a longitudinal control proportional coefficient matrix ∈. The control proportional coefficient matrix is ​​calculated based on the trailer's current tilt and yaw attitude and passed to the assist control execution function.

[0067] If the trailer is currently in a high roll and yaw attitude, i.e., the trailer roll and yaw attitude Tc value is 0.85 < Tc < 1, the lateral control proportional coefficient matrix ε is calculated based on the trailer's current driving attitude:

[0068]

[0069] Where ε is the lateral control proportional coefficient matrix, tc2 is the trailer yaw attitude, μ is the friction coefficient between the road surface and the tire, β is the trailer slip angle, v is the trailer longitudinal speed, and a y L1 represents the lateral acceleration of the trailer, L2 represents the center distance of the rear axle of the trailer, and L3 represents the axle spacing of the trailer.

[0070] Solve the vertical control proportional coefficient matrix ∈:

[0071]

[0072] Wherein, ∈ is the longitudinal control ratio coefficient matrix, tc1 is the trailer tilt attitude, μ is the friction coefficient between the road and the tire, L2 is the center distance of the trailer rear axle, L3 is the axle spacing of the trailer, and k1 is the longitudinal stiffness of the tire, with a value of 1000kN / m.

[0073] The trailer steering control execution unit designs a power assist control execution function based on the calculated lateral control ratio coefficient matrix ε and longitudinal control ratio coefficient matrix ∈, thereby controlling the active steering assist of the trailer.

[0074]

[0075] Among them, F1 * F2 assists in lateral control of trailers. * For longitudinal control of the trailer, ε is the lateral control proportional coefficient matrix, ∈ is the longitudinal control proportional coefficient matrix, F1=[F1 f F1 m F1 r [F2] represents the lateral force on the trailer wheel, F2 = [F2] f F2 m F2 r [This refers to the longitudinal force on the trailer wheels.]

[0076] The trailer steering adjustment unit adjusts the active steering assist of the trailer according to different trailer tilt and yaw attitudes.

[0077] If the trailer is currently in a mid-tilt / yaw attitude, i.e., the trailer's tilt / yaw attitude Tc value is 0.55 < Tc < 0.85, the lateral control proportional coefficient matrix ε is calculated based on the trailer's current driving attitude.

[0078]

[0079] Where ε is the lateral control proportional coefficient matrix, tc2 is the trailer yaw attitude, μ is the friction coefficient between the road surface and the tire, β is the trailer slip angle, v is the trailer longitudinal speed, and a y L1 represents the lateral acceleration of the trailer, L2 represents the center distance of the rear axle of the trailer, and L3 represents the axle spacing of the trailer.

[0080] Solve the vertical control proportional coefficient matrix ∈:

[0081]

[0082] Wherein, ∈ is the longitudinal control ratio coefficient matrix, tc1 is the trailer roll attitude, μ is the friction coefficient between the road and the tire, L2 is the center distance of the trailer rear axle, L3 is the axle spacing of the trailer, and k1 is the longitudinal stiffness of the tire, with a value of 1000kN / m.

[0083] The trailer steering control execution unit designs a power assist control execution function based on the calculated lateral control ratio coefficient matrix ε and longitudinal control ratio coefficient matrix ∈, thereby controlling the active steering assist of the trailer.

[0084]

[0085] Among them, F1 * F2 assists in lateral control of trailers. * For longitudinal control of the trailer, ε is the lateral control proportional coefficient matrix, ∈ is the longitudinal control proportional coefficient matrix, F1=[F1 f F1 m F1 r [F2] represents the lateral force on the trailer wheel, F2 = [F2] f F2 m F2 r [This refers to the longitudinal force on the trailer wheels.]

[0086] The trailer steering adjustment unit adjusts the active steering assist of the trailer according to different trailer tilt and yaw attitudes.

[0087] If the trailer is currently in a low roll and yaw attitude, i.e., the trailer roll and yaw attitude Tc value is 0 < Tc < 0.55, the lateral control proportional coefficient matrix ε is calculated based on the trailer's current driving attitude.

[0088]

[0089] Where ε is the lateral control proportional coefficient matrix, tc2 is the trailer yaw attitude, μ is the friction coefficient between the road surface and the tire, β is the trailer slip angle, v is the trailer longitudinal speed, and a yL1 represents the lateral acceleration of the trailer, L2 represents the center distance of the rear axle of the trailer, and L3 represents the axle spacing of the trailer.

[0090] Solve the vertical control proportional coefficient matrix ∈:

[0091]

[0092] Wherein, ∈ is the longitudinal control ratio coefficient matrix, tc1 is the trailer roll attitude, μ is the friction coefficient between the road and the tire, L2 is the center distance of the trailer rear axle, L3 is the axle spacing of the trailer, and k1 is the longitudinal stiffness of the tire, with a value of 1000kN / m.

[0093] The trailer steering control execution unit designs a power assist control execution function based on the calculated lateral control ratio coefficient matrix ε and longitudinal control ratio coefficient matrix ∈, thereby controlling the active steering assist of the trailer.

[0094]

[0095] Among them, F1 * F2 assists in lateral control of trailers. * For longitudinal control of the trailer, ε is the lateral control proportional coefficient matrix, ∈ is the longitudinal control proportional coefficient matrix, F1=[F1 f F1 m F1 r [F2] represents the lateral force on the trailer wheel, F2 = [F2] f F2 m F2 r [This refers to the longitudinal force on the trailer wheels.]

[0096] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0097] 1. A trailer active steering intelligent control system calculates the trailer attitude degree based on the trailer attitude degree calculation function and assigns a weighting factor to obtain the current trailer tilt and yaw attitude degree. It introduces the trailer steering evaluation factor ρ and calculates the reasonable range of active steering angle of the trailer intermediate axle under the current trailer tilt and yaw attitude degree.

[0098] 2. This invention uses trajectory coordinate offset, trailer lateral acceleration and trailer intermediate axle active steering angle as optimization index control quantities, designs trailer active steering angle optimization index, assigns weight control coefficients to the optimization index control quantities, constructs trailer active steering angle optimization function, and obtains the active steering angle of each axle of the trailer through angle allocation relationship.

[0099] 3. Based on the different lateral tilt and yaw attitudes of the trailer, an adjustment ratio coefficient matrix is ​​introduced, and the power assist control execution function is calculated to adjust the active steering assist of the trailer. Attached Figure Description

[0100] The present invention will be further described below with reference to the accompanying drawings:

[0101] Figure 1 This invention proposes an intelligent control system for active steering of trailers. Detailed Implementation

[0102] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0103] like Figure 1 As shown, the present invention is an intelligent control system for active steering of trailers, including a trailer driving data acquisition unit, a trailer tilt and yaw attitude calculation unit, a trailer coordinate transformation unit, a trailer active steering angle calculation unit, a trailer steering evaluation unit, a trailer steering adjustment unit, and a trailer steering control execution unit.

[0104] The trailer travel data acquisition unit includes a displacement coordinate storage unit for storing the trajectory coordinates of the tractor, a trailer travel side slip angle sensor for acquiring the trailer travel side slip angle β, a trailer travel side tilt angle sensor for acquiring the trailer travel side tilt angle φ, and a trailer travel yaw rate sensor for acquiring the trailer travel yaw rate. The trailer lateral acceleration sensor is used to obtain the trailer lateral acceleration a. y The wheel resistance sensor is used to detect the friction coefficient μ between the road surface and the tire; based on the collected data required for calculating the attitude angle, it is provided to the vehicle driving attitude angle calculation unit.

[0105] The trailer tilt and yaw attitude calculation unit includes a trailer attitude calculation function, designs trailer tilt attitude calculation factor θ1 and trailer yaw attitude calculation factor θ2, and calculates the current trailer driving attitude based on the data information collected by the sensors in the trailer driving data acquisition unit using the trailer attitude calculation function.

[0106] The trailer attitude calculation function is shown in the following formula:

[0107]

[0108] Where Tc is the trailer roll and yaw attitude, τ1 is the sideslip angle correction factor, τ2 is the roll weighting factor, τ3 is the yaw weighting factor, β is the trailer travel sideslip angle, tc1 is the trailer roll attitude, and tc2 is the trailer yaw attitude.

[0109] The trailer coordinate transformation unit converts the coordinate system of the tractor's front axle center to the trailer's coordinate system. By analyzing and calculating the coordinates of the trailer's own rear axle center, the trajectory coordinate offset e can be obtained. s ;

[0110] The trailer active steering angle calculation unit uses the trajectory coordinate offset, trailer lateral acceleration, and trailer intermediate axle active steering angle as optimization index control quantities to construct a trailer active steering angle optimization function, and obtains the active steering angle of each axle of the trailer using the steering angle distribution relationship:

[0111]

[0112] Among them, J t To optimize the active steering angle of the trailer, a y e represents the lateral acceleration of the trailer. s δ is the trajectory coordinate offset. m The active steering angle of the trailer's intermediate axle is denoted by χ1, where χ1 is the weighted control coefficient for the trailer's lateral acceleration, χ2 is the weighted control coefficient for the trajectory coordinate offset, and χ3 is the weighted control coefficient for the trailer's rear axle steering angle. The trailer steering evaluation unit needs to differentiate the attitude threshold based on the trailer roll and yaw attitude Tc value calculated by the trailer roll and yaw attitude calculation unit, introducing a trailer steering evaluation factor ρ to calculate the reasonable range δ of the active steering angle of the trailer's intermediate axle under the current trailer roll and yaw attitude. m * (If the trailer's yaw attitude value Tc is 0.85 < Tc < 1 at this time, it is determined that the trailer is currently in a high yaw attitude):

[0113]

[0114] Where, ρ min ρ represents the minimum value within the range of the trailer steering evaluation factor ρ. max The maximum value of the trailer steering evaluation factor ρ is given within its range, Tc is the current trailer roll and yaw attitude, and δ is the maximum value of the trailer steering evaluation factor ρ within its range. m * min δ is the minimum reasonable range of active steering angle for the intermediate axle of the trailer. m * max δ represents the maximum value within the reasonable range of the active steering angle of the trailer's intermediate axle. m * min ≤δ m * ≤δ m * max ;

[0115] The trailer steering adjustment unit adjusts the active steering assist of the trailer according to different trailer tilt and yaw attitudes. It introduces a lateral control proportional coefficient matrix ε and a longitudinal control proportional coefficient matrix ∈. The control proportional coefficient matrix is ​​calculated based on the trailer's current tilt and yaw attitude and transmitted to the trailer steering control execution unit.

[0116] The trailer steering control execution unit designs a power assist control execution function based on the calculated lateral control ratio coefficient matrix and longitudinal control ratio coefficient matrix, thereby controlling the active steering assist of the trailer.

[0117] The trailer roll and yaw attitude calculation unit needs to use the designed trailer roll attitude calculation factor θ1 and trailer yaw attitude calculation factor θ2 to perform preliminary calculations to obtain trailer roll attitude tc1 and trailer yaw attitude tc2.

[0118] Based on the trailer roll angle φ collected by the trailer roll angle sensor in the trailer travel data acquisition unit, there is a trailer roll attitude solution factor θ1. The range of θ1 is limited to 0.5 < θ1 < 1. It is positively correlated with the degree of trailer roll. The larger the roll angle, the larger the value of the roll attitude solution factor θ1, and vice versa.

[0119] Based on the preliminary calculation method for the trailer roll attitude, a corresponding trailer roll attitude calculation factor θ1 is assigned to the trailer roll angle φ, and the roll attitude tc1 is calculated.

[0120]

[0121] Where φ is the trailer roll angle and θ1 is the trailer roll attitude factor;

[0122] The trailer yaw rate is collected by the trailer yaw rate sensor in the trailer driving data acquisition unit. There is a trailer yaw attitude solution factor θ2, the range of which is limited to 0 < θ2 < 0.85. It is positively correlated with the degree of yaw of the trailer. The larger the yaw angle, the larger the value of the yaw attitude solution factor θ2, and vice versa.

[0123] Based on the preliminary calculation method for yaw attitude, a corresponding trailer yaw attitude calculation factor θ2 is assigned to the trailer yaw angle φ, and the trailer yaw attitude tc2 is calculated.

[0124]

[0125] Where φ is the trailer yaw angle, which is determined by the trailer yaw rate. Points can be obtained θ2 is the factor for calculating the trailer yaw attitude.

[0126] The trailer attitude calculation function, after completing the initial calculation of the trailer roll attitude tc1 and trailer yaw attitude tc2, assigns a roll angle correction factor τ1, a roll weighting factor τ2, and a yaw weighting factor τ3 to the trailer travel sideslip angle, trailer roll attitude, and trailer yaw attitude, respectively, as follows:

[0127]

[0128] Where Tc is the trailer roll and yaw attitude, τ1 is the sideslip angle correction factor, τ2 is the roll weighting factor, τ3 is the yaw weighting factor, β is the trailer travel sideslip angle, tc1 is the trailer roll attitude, and tc2 is the trailer yaw attitude.

[0129] The trailer coordinate transformation unit analyzes and calculates the tractor trajectory coordinates stored in the displacement coordinate storage device. The tractor front axle center trajectory stored in the displacement coordinate storage device is as follows:

[0130]

[0131] Where X is the trajectory of the center of the front axle of the tractor along the X-axis, Y is the trajectory of the center of the front axle of the tractor along the Y-axis, and x1(n) and y1(n) are the instantaneous coordinates of different coordinate points at the center of the front axle of the tractor along the X and Y axes.

[0132] Instantaneous coordinates of the trailer's intermediate axle center along the X and Y axes during travel:

[0133]

[0134] Where x2(n) and y2(n) are the instantaneous coordinates of different coordinate points traveling at the center of the intermediate axle of the trailer along the X and Y axes, L1 is the center distance of the front axle of the tractor, L2 is the center distance of the rear axle of the trailer, v is the longitudinal speed of the trailer, φ is the yaw angle of the trailer, β is the side slip angle of the trailer, and φ is the side tilt angle of the trailer.

[0135] The coordinate transformation unit is used to convert the coordinate system of the tractor's front axle center to the coordinate system of the trailer:

[0136]

[0137] Among them, X 12 (n) represents the instantaneous coordinates of the tractor's front axle center, converted from the coordinate system to the trailer coordinate system along the X-axis, where Y... 12 (n) represents the instantaneous coordinates of the center of the front axle of the tractor converted from the coordinate system to the coordinate system of the trailer along the Y-axis, L1 is the center distance of the front axle of the tractor, L2 is the center distance of the rear axle of the trailer, φ is the yaw angle of the trailer, and β is the side slip angle of the trailer.

[0138] The trailer active steering angle calculation unit will calculate the offset based on the coordinates in the coordinate system transformed by the trailer coordinate transformation unit, and then calculate the trailer active steering angle:

[0139] At this point, the trajectory coordinate offset e can be obtained by calculating the trajectory coordinates between the rear axle center of the trailer and the front axle center of the tractor after conversion. s :

[0140]

[0141] Among them, e s Y is the trajectory coordinate offset. 12 (i+1) represents the instantaneous coordinates of the tractor's front axle center along the Y-axis, converted from the tractor's coordinate system to the trailer's coordinate system. 12 (i) represents the instantaneous coordinates of the center of the front axle of the tractor vehicle along the Y-axis direction, converted from the coordinate system of the tractor vehicle's coordinate point (i) to the trailer coordinate system. 12 (i+1) represents the instantaneous coordinates of the tractor's front axle center along the X-axis, converted from the tractor's coordinate system to the trailer's coordinate system. 12 (i) represents the instantaneous coordinates of the center of the front axle of the tractor vehicle along the X-axis direction at coordinate point (i) in the tractor vehicle coordinate system converted to the trailer coordinate system.

[0142] Using trajectory coordinate offset, trailer lateral acceleration, and trailer intermediate axle active steering angle as optimization control parameters, an optimization index for trailer active steering angle is designed. Weighted control coefficients are assigned to each optimization control parameter, and an optimization function for trailer active steering angle is constructed.

[0143]

[0144] Among them, J t To optimize the active steering angle of the trailer, a y e represents the lateral acceleration of the trailer. s δ is the trajectory coordinate offset. m χ1 is the weighted control coefficient of the trailer's lateral acceleration, χ2 is the weighted control coefficient of the trajectory coordinate offset, and χ3 is the weighted control coefficient of the trailer's intermediate axle's active steering angle.

[0145] By determining the values ​​of the weight control coefficients, the optimization index J of the trailer's active steering angle is calculated. t :

[0146]

[0147] Among them, J tThe active steering angle optimization index for trailers is defined as follows: τ1 is the slip angle correction factor, τ2 is the roll weighting factor, τ3 is the yaw weighting factor, tc1 is the trailer roll attitude, tc2 is the trailer yaw attitude, χ1 is the weight control coefficient of trailer lateral acceleration, χ2 is the weight control coefficient of trajectory coordinate offset, and χ3 is the weight control coefficient of trailer intermediate axle steering angle.

[0148] The control quantity, the active steering angle δ of the trailer intermediate axle, is obtained by solving the optimization function of the trailer's active steering angle. m To ensure that the lateral forces on each axle of the trailer are equal and to distribute the trailer's turning angles taking into account the turning angle relationships of each axle:

[0149]

[0150] Where, δ f For the active steering angle of the trailer's front axle, δ m δ is the active steering angle of the intermediate axle of the trailer. r L3 is the active steering angle of the trailer's rear axle, L4 is the axle spacing of the trailer, and v is the longitudinal speed of the trailer. This represents the yaw rate of the trailer.

[0151] The trailer steering evaluation unit needs to distinguish the attitude threshold based on the trailer tilt and yaw attitude Tc value calculated by the trailer tilt and yaw attitude calculation unit. Under the condition that the vehicle does not have an accident, the size range of the trailer tilt and yaw attitude Tc is 0 < Tc < 1. The larger the calculated Tc value, the greater the tilt and yaw attitude of the trailer, that is, the trailer driving attitude is unstable and prone to accidents such as rollover and fishtailing. Conversely, the smaller the calculated Tc value, the smaller the tilt and yaw attitude of the trailer, and the better the trailer driving stability.

[0152] A trailer steering evaluation factor ρ is introduced, with a limit of 0.3 ≤ ρ ≤ 1. Within this range, the trailer steering evaluation factor ρ serves as the control index for safe trailer steering, meaning that the intermediate axle steering angle calculated by the trailer active steering angle calculation unit must be within the reasonable range δ of the trailer intermediate axle active steering angle under the current roll and yaw attitude. m * Inside;

[0153] If the trailer roll and yaw attitude value Tc is 0.85 < Tc < 1, then the trailer is determined to be in a high roll and yaw attitude. Using the trailer roll and yaw attitude calculation unit to calculate the trailer roll and yaw attitude value Tc and the trailer steering evaluation factor ρ, the reasonable range δ of the active steering angle of the trailer's intermediate axle under the current trailer roll and yaw attitude is calculated. m * :

[0154]

[0155] Where, ρ min ρ represents the minimum value within the range of the trailer steering evaluation factor ρ. max The maximum value of the trailer steering evaluation factor ρ is given within its range, Tc is the current trailer roll and yaw attitude, and δ is the maximum value of the trailer steering evaluation factor ρ within its range. m * min δ is the minimum reasonable range of active steering angle for the intermediate axle of the trailer. m * max δ represents the maximum value within the reasonable range of the active steering angle of the trailer's intermediate axle. m * min ≤δ m * ≤δ m * max ;

[0156] If the trailer roll and yaw attitude value Tc is 0.55 < Tc < 0.85 at this time, it is determined that the trailer is currently in a medium roll and yaw attitude. Using the trailer roll and yaw attitude calculation unit to calculate the trailer roll and yaw attitude value Tc and the trailer steering evaluation factor ρ, the reasonable range δ of the active steering angle of the trailer's intermediate axle under the current trailer roll and yaw attitude is calculated. m * :

[0157]

[0158] Where, ρ min ρ represents the minimum value within the range of the trailer steering evaluation factor ρ. max The maximum value of the trailer steering evaluation factor ρ is given within its range, Tc is the current trailer roll and yaw attitude, and δ is the maximum value of the trailer steering evaluation factor ρ within its range. m * min δ is the minimum reasonable range of active steering angle for the intermediate axle of the trailer. m * max δ represents the maximum value within the reasonable range of the active steering angle of the trailer's intermediate axle. m * min ≤δ m * ≤δ m * max ;

[0159] If the trailer roll and yaw attitude value Tc is 0 < Tc < 0.55, then the trailer is determined to be in a low roll and yaw attitude. Using the trailer roll and yaw attitude calculation unit to calculate the trailer roll and yaw attitude value Tc and the trailer steering evaluation factor ρ, the reasonable range δ of the active steering angle of the trailer's intermediate axle under the current trailer roll and yaw attitude is calculated. m * :

[0160]

[0161] Where, ρ min ρ represents the minimum value within the range of the trailer steering evaluation factor ρ. max The maximum value of the trailer steering evaluation factor ρ is given within its range, Tc is the current trailer roll and yaw attitude, and δ is the maximum value of the trailer steering evaluation factor ρ within its range. m * min δ is the minimum reasonable range of active steering angle for the intermediate axle of the trailer. m * max δ represents the maximum value within the reasonable range of the active steering angle of the trailer's intermediate axle. m * min ≤δ m * ≤δ m * max .

[0162] The trailer steering adjustment unit adjusts the active steering assist of the trailer according to different trailer tilt and yaw attitudes. It introduces a lateral control proportional coefficient matrix ε and a longitudinal control proportional coefficient matrix ∈. The control proportional coefficient matrix is ​​calculated based on the trailer's current tilt and yaw attitude and passed to the assist control execution function.

[0163] If the trailer is currently in a high roll and yaw attitude, i.e., the trailer roll and yaw attitude Tc value is 0.85 < Tc < 1, the lateral control proportional coefficient matrix ε is calculated based on the trailer's current driving attitude:

[0164]

[0165] Where ε is the lateral control proportional coefficient matrix, tc2 is the trailer yaw attitude, μ is the friction coefficient between the road surface and the tire, β is the trailer slip angle, v is the trailer longitudinal speed, and a y L1 represents the lateral acceleration of the trailer, L2 represents the center distance of the rear axle of the trailer, and L3 represents the axle spacing of the trailer.

[0166] Solve the vertical control proportional coefficient matrix ∈:

[0167]

[0168] Wherein, ∈ is the longitudinal control ratio coefficient matrix, tc1 is the trailer tilt attitude, μ is the friction coefficient between the road and the tire, L2 is the center distance of the trailer rear axle, L3 is the axle spacing of the trailer, and k1 is the longitudinal stiffness of the tire, with a value of 1000kN / m.

[0169] The trailer steering control execution unit designs a power assist control execution function based on the calculated lateral control ratio coefficient matrix ε and longitudinal control ratio coefficient matrix ∈, thereby controlling the active steering assist of the trailer.

[0170]

[0171] Among them, F1 * F2 assists in lateral control of trailers. * For longitudinal control of the trailer, ε is the lateral control proportional coefficient matrix, ∈ is the longitudinal control proportional coefficient matrix, F1=[F1 f F1 m F1 r [F2] represents the lateral force on the trailer wheel, F2 = [F2] f F2 m F2 r [This refers to the longitudinal force on the trailer wheels.]

[0172] The trailer steering adjustment unit adjusts the active steering assist of the trailer according to different trailer tilt and yaw attitudes.

[0173] If the trailer is currently in a mid-tilt / yaw attitude, i.e., the trailer's tilt / yaw attitude Tc value is 0.55 < Tc < 0.85, the lateral control proportional coefficient matrix ε is calculated based on the trailer's current driving attitude.

[0174]

[0175] Where ε is the lateral control proportional coefficient matrix, tc2 is the trailer yaw attitude, μ is the friction coefficient between the road surface and the tire, β is the trailer slip angle, v is the trailer longitudinal speed, and a y L1 represents the lateral acceleration of the trailer, L2 represents the center distance of the rear axle of the trailer, and L3 represents the axle spacing of the trailer.

[0176] Solve the vertical control proportional coefficient matrix ∈:

[0177]

[0178] Wherein, ∈ is the longitudinal control ratio coefficient matrix, tc1 is the trailer roll attitude, μ is the friction coefficient between the road and the tire, L2 is the center distance of the trailer rear axle, L3 is the axle spacing of the trailer, and k1 is the longitudinal stiffness of the tire, with a value of 1000kN / m.

[0179] The trailer steering control execution unit designs a power assist control execution function based on the calculated lateral control ratio coefficient matrix ε and longitudinal control ratio coefficient matrix ∈, thereby controlling the active steering assist of the trailer.

[0180]

[0181] Among them, F1 * F2 assists in lateral control of trailers. * For longitudinal control of the trailer, ε is the lateral control proportional coefficient matrix, ∈ is the longitudinal control proportional coefficient matrix, F1=[F1 f F1 m F1 r [F2] represents the lateral force on the trailer wheel, F2 = [F2] f F2 m F2 r [This refers to the longitudinal force on the trailer wheels.]

[0182] The trailer steering adjustment unit adjusts the active steering assist of the trailer according to different trailer tilt and yaw attitudes.

[0183] If the trailer is currently in a low roll and yaw attitude, i.e., the trailer roll and yaw attitude Tc value is 0 < Tc < 0.55, the lateral control proportional coefficient matrix ε is calculated based on the trailer's current driving attitude.

[0184]

[0185] Where ε is the lateral control proportional coefficient matrix, tc2 is the trailer yaw attitude, μ is the friction coefficient between the road surface and the tire, β is the trailer slip angle, v is the trailer longitudinal speed, and a y L1 represents the lateral acceleration of the trailer, L2 represents the center distance of the rear axle of the trailer, and L3 represents the axle spacing of the trailer.

[0186] Solve the vertical control proportional coefficient matrix ∈:

[0187]

[0188] Wherein, ∈ is the longitudinal control ratio coefficient matrix, tc1 is the trailer roll attitude, μ is the friction coefficient between the road and the tire, L2 is the center distance of the trailer rear axle, L3 is the axle spacing of the trailer, and k1 is the longitudinal stiffness of the tire, with a value of 1000kN / m.

[0189] The trailer steering control execution unit designs a power assist control execution function based on the calculated lateral control ratio coefficient matrix ε and longitudinal control ratio coefficient matrix ∈, thereby controlling the active steering assist of the trailer.

[0190]

[0191] Among them, F1 * F2 assists in lateral control of trailers. * For longitudinal control of the trailer, ε is the lateral control proportional coefficient matrix, ∈ is the longitudinal control proportional coefficient matrix, F1=[F1 f F1 m F1 r [F2] represents the lateral force on the trailer wheel, F2 = [F2] f F2 m F2 r [This refers to the longitudinal force on the trailer wheels.]

Claims

1. A smart control system for active steering of trailers, characterized in that, Includes the following: trailer driving data acquisition unit, trailer side tilt and yaw attitude calculation unit, trailer coordinate transformation unit, trailer active steering angle calculation unit, trailer steering evaluation unit, trailer steering adjustment unit, and trailer steering control execution unit; The trailer driving data acquisition unit includes a displacement coordinate storage device for storing the trajectory coordinates of the tractor and a trailer driving side slip angle sensor for acquiring the trailer driving side slip angle. The trailer roll angle sensor is used to obtain the trailer roll angle. The trailer yaw rate sensor is used to obtain the trailer's yaw rate. The trailer lateral acceleration sensor is used to obtain the trailer's lateral acceleration. Wheel resistance sensors are used to detect the coefficient of friction between the road surface and the tire. The data collected by the trailer driving data acquisition unit is provided to the vehicle driving attitude angle calculation unit. The trailer roll and yaw attitude calculation unit includes a trailer attitude calculation function and designs trailer roll attitude calculation factors. Trailer yaw attitude calculation factor The current trailer driving attitude is calculated using the trailer attitude calculation function based on the data collected by the sensors in the trailer driving data acquisition unit. The trailer attitude calculation function is shown in the following formula: ， in, To assess the trailer's tilt and yaw attitude. This is the side slip angle correction factor. As the tilt weighting factor, As the horizontal weighting factor, This refers to the trailer's side slip angle during travel. This refers to the trailer's tilt attitude. The sway posture of the trailer; The trailer coordinate transformation unit converts the coordinate system of the tractor's front axle center to the trailer's coordinate system. By analyzing and calculating the coordinates of the trailer's own rear axle center, the trajectory coordinate offset can be obtained. ; The trailer active steering angle calculation unit uses the trajectory coordinate offset, trailer lateral acceleration, and trailer intermediate axle active steering angle as optimization index control quantities to construct a trailer active steering angle optimization function, and obtains the active steering angle of each axle of the trailer using the steering angle distribution relationship: ， in, Optimize the active steering angle of the trailer. The lateral acceleration of the trailer. This is the trajectory coordinate offset. This refers to the active steering angle of the trailer's intermediate axle. This is the weighted control coefficient for the lateral acceleration of the trailer. The weighting control coefficient for trajectory coordinate offset. This is the weighted control coefficient for the steering angle of the trailer's rear axle; The trailer steering assessment unit needs to calculate the trailer tilt and yaw attitude based on the trailer tilt and yaw attitude calculation unit. Values ​​are used to differentiate between attitude thresholds, and a trailer steering evaluation factor is introduced. Calculate the reasonable range of active steering angle of the trailer's intermediate axle under the current trailer tilt and yaw attitude. (If the trailer is tilting or swaying at this time) The value is 0.85 < <1, indicating the trailer is currently in a high yaw / tilt position. ， in, For trailer steering evaluation factors The minimum value within the range of values. For trailer steering evaluation factors The maximum value within the range of values. The current side tilt and yaw attitude of the trailer. This represents the minimum reasonable range for the active steering angle of the trailer's intermediate axle. This represents the maximum value within the reasonable range of the active steering angle of the trailer's intermediate axle. ≤ ≤ ; The trailer steering adjustment unit adjusts the active steering assist of the trailer accordingly based on different trailer tilt and yaw attitudes, introducing a lateral control proportional coefficient matrix. Vertical control proportional coefficient matrix The control ratio coefficient matrix is ​​calculated based on the trailer's current tilt and yaw attitude and then transmitted to the trailer steering control execution unit. The trailer steering control execution unit designs a power assist control execution function based on the calculated lateral control ratio coefficient matrix and longitudinal control ratio coefficient matrix, thereby controlling the active steering assist of the trailer.

2. The intelligent control system for active steering of trailers according to claim 1, characterized in that, The trailer roll and yaw attitude calculation unit needs to reference the designed trailer roll attitude calculation factor. Trailer yaw attitude calculation factor Preliminary calculations were performed to obtain the trailer's lateral tilt attitude. Trailer yaw attitude during driving ; The trailer roll angle is collected by the trailer roll angle sensor in the trailer travel data acquisition unit. There are trailer roll attitude factor calculation factors. , The size range is limited to 0.5 < <1, is positively correlated with the degree of lateral tilt during trailer travel; the larger the tilt angle, the higher the lateral tilt attitude calculation factor. The larger the value, the smaller the value. Based on the preliminary calculation method for roll attitude, the trailer's roll angle during travel is... Assign corresponding trailer roll attitude factor The roll attitude was calculated. : ， in, This refers to the trailer's tilt angle during travel. Factors for calculating the trailer's roll attitude; The trailer yaw rate is collected by the trailer yaw rate sensor in the trailer driving data acquisition unit. There are trailer yaw attitude solution factors. , Size range limited to 0 < <0.85, positively correlated with the yaw rate of the trailer; the larger the yaw angle, the higher the yaw attitude factor. The larger the value, the smaller the value. Based on the preliminary calculation method for yaw attitude, the trailer's yaw angle during travel is... Assign corresponding trailer yaw attitude factor The yaw attitude of the trailer was calculated. : ， in, Let yaw angle be the trailer yaw angle, and let yaw rate be the trailer yaw rate. Points can be obtained ; Calculate the factors for the trailer's yaw attitude. The trailer attitude calculation function, after completing the calculation of the trailer roll attitude... yaw attitude of trailer After the initial calculation, slip angle correction factors are assigned to the trailer's slip angle, trailer roll attitude, and trailer yaw attitude, respectively. Tilt weighting factor Horizontal weighting factor The following formula exists: ， in, To assess the trailer's tilt and yaw attitude. This is the side slip angle correction factor. As the tilt weighting factor, As the horizontal weighting factor, This refers to the trailer's side slip angle during travel. This refers to the trailer's tilt attitude. This refers to the lateral sway posture of the trailer.

3. The intelligent control system for active steering of trailers according to claim 1, characterized in that, The trailer coordinate transformation unit analyzes and calculates the tractor trajectory coordinates stored in the displacement coordinate storage device. The tractor front axle center trajectory stored in the displacement coordinate storage device is as follows: ， in, The trajectory of the center of the front axle of the tractor along the X-axis. The trajectory of the center of the front axle of the tractor along the Y-axis. These are the instantaneous coordinates of the displacement of different coordinate points along the X and Y axes at the center of the front axle of the tractor. Instantaneous coordinates of the trailer's intermediate axle center along the X and Y axes during travel: ， in, Let X and Y be the instantaneous coordinates of the displacement of different coordinate points along the X and Y axes at the center of the trailer's intermediate axle. This is the center distance of the front axle of the tractor. This is the center distance between the rear axles of the trailer. The longitudinal speed of the trailer. For trailer yaw angle, This refers to the trailer's side slip angle. This refers to the trailer's tilt angle during travel. The coordinate transformation unit is used to convert the coordinate system of the tractor's front axle center to the coordinate system of the trailer: ， in, To convert the coordinate system of the tractor's front axle center along the X-axis to the trailer's coordinate system for instantaneous coordinates. To convert the coordinate system of the tractor's front axle center along the Y-axis to the trailer's coordinate system for instantaneous coordinates. This is the center distance of the front axle of the tractor. This is the center distance between the rear axles of the trailer. This refers to the yaw angle of the trailer during travel. This refers to the trailer's side slip angle.

4. The intelligent control system for active steering of trailers according to claim 1, characterized in that, The trailer active steering angle calculation unit will calculate the offset based on the coordinates in the coordinate system transformed by the trailer coordinate transformation unit, and then calculate the trailer active steering angle: At this point, the trajectory coordinate offset between the rear axle center of the trailer and the front axle center of the tractor after conversion can be obtained by calculating the trajectory coordinates. : , in, This is the trajectory coordinate offset. Coordinates of the tractor The coordinate system of the center of the front axle of the tractor is converted to the instantaneous coordinate system of the trailer along the Y-axis. Coordinates of the tractor The coordinate system of the center of the front axle of the tractor is converted to the instantaneous coordinate system of the trailer along the Y-axis. Coordinates of the tractor The coordinate system of the center of the front axle of the tractor is converted to the instantaneous coordinate system of the trailer along the X-axis. Coordinates of the tractor The coordinate system of the center of the front axle of the tractor along the X-axis is converted to the instantaneous coordinate system of the trailer. Using trajectory coordinate offset, trailer lateral acceleration, and trailer intermediate axle active steering angle as optimization control parameters, an optimization index for trailer active steering angle is designed. Weighted control coefficients are assigned to each optimization control parameter, and an optimization function for trailer active steering angle is constructed. ， in, Optimize the active steering angle of the trailer. The lateral acceleration of the trailer. This is the trajectory coordinate offset. This refers to the active steering angle of the trailer's intermediate axle. This is the weighted control coefficient for the lateral acceleration of the trailer. The weighting control coefficient for trajectory coordinate offset. This is the weighting control coefficient for the active steering angle of the trailer's intermediate axle; By determining the values ​​of the weighted control coefficients, the optimization index for the active steering angle of the trailer is calculated. : ， in, Optimize the active steering angle of the trailer. This is the side slip angle correction factor. As the tilt weighting factor, As the horizontal weighting factor, This refers to the trailer's tilt attitude. To determine the yaw attitude of the trailer, This is the weighted control coefficient for the lateral acceleration of the trailer. The weighting control coefficient for trajectory coordinate offset. This is the weighted control coefficient for the steering angle of the trailer's intermediate axle; The control quantity, the active steering angle of the trailer intermediate axle, is obtained by solving the optimization function of the trailer's active steering angle. To ensure that the lateral forces on each axle of the trailer are equal and to distribute the trailer's turning angles taking into account the turning angle relationships of each axle: ， ， in, This refers to the active steering angle of the trailer's front axle. This refers to the active steering angle of the trailer's intermediate axle. This is the active steering angle of the trailer's rear axle. This refers to the axle spacing of the trailer. The longitudinal speed of the trailer. This represents the yaw rate of the trailer.

5. The intelligent control system for active steering of trailers according to claim 1, characterized in that, The trailer steering assessment unit needs to calculate the trailer tilt and yaw attitude based on the trailer tilt and yaw attitude calculation unit. The values ​​are used to distinguish the attitude thresholds, and the trailer's roll and yaw attitude is measured under the condition that the vehicle is not involved in any accidents. The size range is 0 < <1, obtained from the solution A larger value indicates a greater lateral tilt and yaw rate of the trailer, meaning the trailer's driving posture is unstable and prone to accidents such as rollovers and fishtailing. Conversely, a smaller value indicates a greater risk of accidents. The smaller the value, the smaller the lateral tilt and yaw attitude of the trailer, and the better the trailer's driving stability. Introducing trailer steering evaluation factors ,limit The size range is Trailer steering evaluation factor within this range This refers to the evaluation index for the safe steering of the trailer, specifically, ensuring that the intermediate axle steering angle calculated by the trailer's active steering angle calculation unit is within a reasonable range for the trailer's intermediate axle active steering angle under the current roll and yaw attitude. Inside; If the trailer is tilting and swaying at this time Value 0.85 < If the value is less than 1, the trailer is determined to be in a high tilt and yaw attitude. The trailer tilt and yaw attitude is calculated by the trailer tilt and yaw attitude calculation unit. and trailer steering evaluation factors Calculate the reasonable range of active steering angle of the trailer's intermediate axle under the current trailer tilt and yaw attitude. : ， in, For trailer steering evaluation factors The minimum value within the range of values. For trailer steering evaluation factors The maximum value within the range of values. The current side tilt and yaw attitude of the trailer. This represents the minimum reasonable range for the active steering angle of the trailer's intermediate axle. This represents the maximum value within the reasonable range of the active steering angle of the trailer's intermediate axle. ≤ ≤ ; If the trailer is tilting and swaying at this time Value 0.55 < If the value is less than 0.85, the trailer is determined to be in a mid-tilt / yaw attitude. The trailer tilt / yaw attitude is calculated by the trailer tilt / yaw attitude calculation unit. and trailer steering evaluation factors Calculate the reasonable range of active steering angle of the trailer's intermediate axle under the current trailer tilt and yaw attitude. : ， in, For trailer steering evaluation factors The minimum value within the range of values. For trailer steering evaluation factors The maximum value within the range of values. The current side tilt and yaw attitude of the trailer. This represents the minimum reasonable range for the active steering angle of the trailer's intermediate axle. This represents the maximum value within the reasonable range of the active steering angle of the trailer's intermediate axle. ≤ ≤ ; If the trailer is tilting and swaying at this time value 0 < If the value is less than 0.55, the trailer is determined to be in a low roll and yaw attitude. The trailer roll and yaw attitude is calculated by the trailer roll and yaw attitude calculation unit. and trailer steering evaluation factors Calculate the reasonable range of active steering angle of the trailer's intermediate axle under the current trailer tilt and yaw attitude. : ， in, For trailer steering evaluation factors The minimum value within the range of values. For trailer steering evaluation factors The maximum value within the range of values. The current side tilt and yaw attitude of the trailer. This represents the minimum reasonable range for the active steering angle of the trailer's intermediate axle. This represents the maximum value within the reasonable range of the active steering angle of the trailer's intermediate axle. ≤ ≤ .

6. The intelligent control system for active steering of trailers according to claim 1, characterized in that, The trailer steering adjustment unit adjusts the active steering assist of the trailer according to different trailer tilt and yaw attitudes, introducing a lateral control proportional coefficient matrix. Vertical control proportional coefficient matrix The control ratio coefficient matrix is ​​calculated based on the trailer's current tilt and yaw attitude and then passed to the power assist control execution function. If the trailer is currently in a high tilt and yaw attitude, i.e., the trailer tilt and yaw attitude... The value is 0.85 < When <1, the lateral control proportional coefficient matrix is ​​calculated based on the trailer's driving attitude at this time. : ， in, This is the lateral control proportional coefficient matrix. To determine the yaw attitude of the trailer, The coefficient of friction between the road surface and the tire. The trailer's side slip angle during travel. The longitudinal speed of the trailer. The lateral acceleration of the trailer. This is the center distance between the rear axles of the trailer. This refers to the axle spacing of the trailer; Solving the vertical control proportional coefficient matrix : ， in, This is the vertical control ratio coefficient matrix. This refers to the trailer's tilt attitude. The coefficient of friction between the road surface and the tire. This is the center distance between the rear axles of the trailer. This refers to the axle spacing of the trailer. This represents the longitudinal stiffness of the tire, with a value of 1000 kN / m. The trailer steering control execution unit is based on the calculated lateral control proportional coefficient matrix. Vertical control proportional coefficient matrix The design assists in controlling the trailer's active steering assist function. ， in, To assist in lateral control of the trailer, To facilitate longitudinal adjustment of the trailer, This is the lateral control proportional coefficient matrix. This is the vertical control ratio coefficient matrix. The lateral force of the trailer wheels. This refers to the longitudinal force on the trailer wheels.

7. The intelligent control system for active steering of trailers according to claim 1, characterized in that, The trailer steering adjustment unit adjusts the active steering assist of the trailer according to different trailer tilt and yaw attitudes. If the trailer is currently in a mid-tilt / yaw attitude, that is, the trailer is in a yaw / yaw attitude. The value is 0.55 < When <0.85, the lateral control proportional coefficient matrix is ​​calculated based on the trailer's driving attitude at this time. : ， in, This is the lateral control proportional coefficient matrix. To determine the yaw attitude of the trailer, The coefficient of friction between the road surface and the tire. The trailer's side slip angle during travel. The longitudinal speed of the trailer. The lateral acceleration of the trailer. This is the center distance between the rear axles of the trailer. This refers to the axle spacing of the trailer; Solving the vertical control proportional coefficient matrix : ， Among them, among them, This is the vertical control ratio coefficient matrix. This refers to the trailer's tilt attitude. The coefficient of friction between the road surface and the tire. This is the center distance between the rear axles of the trailer. This refers to the axle spacing of the trailer. This represents the longitudinal stiffness of the tire, with a value of 1000 kN / m. The trailer steering control execution unit is based on the calculated lateral control proportional coefficient matrix. Vertical control proportional coefficient matrix The design assists in controlling the trailer's active steering assist function. ， in, To assist in lateral control of the trailer, To facilitate longitudinal adjustment of the trailer, This is the lateral control proportional coefficient matrix. This is the vertical control ratio coefficient matrix. The lateral force of the trailer wheels. This refers to the longitudinal force on the trailer wheels.

8. The intelligent control system for active steering of trailers according to claim 1, characterized in that, The trailer steering adjustment unit adjusts the active steering assist of the trailer according to different trailer tilt and yaw attitudes. If the trailer is currently in a low roll and yaw attitude, i.e., the trailer roll and yaw attitude is... The value is 0 < When <0.55, the lateral control proportional coefficient matrix is ​​calculated based on the trailer's driving attitude at this time. : ， in, This is the lateral control proportional coefficient matrix. To determine the yaw attitude of the trailer, The coefficient of friction between the road surface and the tire. The trailer's side slip angle during travel. The longitudinal speed of the trailer. The lateral acceleration of the trailer. This is the center distance between the rear axles of the trailer. This refers to the axle spacing of the trailer; Solving the vertical control proportional coefficient matrix : ， Among them, among them, This is the vertical control ratio coefficient matrix. This refers to the trailer's tilt attitude. The coefficient of friction between the road surface and the tire. This is the center distance between the rear axles of the trailer. This refers to the axle spacing of the trailer. This represents the longitudinal stiffness of the tire, with a value of 1000 kN / m. The trailer steering control execution unit is based on the calculated lateral control proportional coefficient matrix. Vertical control proportional coefficient matrix The design assists in controlling the trailer's active steering assist function. ， in, To assist in lateral control of the trailer, To facilitate longitudinal adjustment of the trailer, This is the lateral control proportional coefficient matrix. This is the vertical control ratio coefficient matrix. The lateral force of the trailer wheels. This refers to the longitudinal force on the trailer wheels.

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