阅读说明：本技术 一种智能车双电机线控转向系统跟踪及同步控制方法 (Tracking and synchronous control method for dual-motor steer-by-wire system of intelligent vehicle ) 是由 邹松春 赵万忠 梁为何 王春燕 张寒 于 2021-07-12 设计创作，主要内容包括：本发明公开了一种智能车双电机线控转向系统跟踪及同步控制方法,智能车双电机线控转向系统包括转向盘转角传感器、车速传感器、变传动比模块和转向执行模块；转向执行模块中的转向电机A、转向电机B采用转角环、电流环双闭环控制,其中转角环采用二阶自抗扰控制器控制,电流环采用滑模控制器控制,从而加强双电机线控转向系统的跟踪性能；此外,转向电机A和转向电机B之间采用交叉耦合同步控制结构,采集转向电机A和转向电机B的实际转角做差经过同步控制器得到的补偿电流信号给转向电机A和转向电机B的电流环,消除转向电机A和转向电机B之间转角不一致性,从而加强双电机线控转向系统的同步性能。(The invention discloses a tracking and synchronous control method of a double-motor steer-by-wire system of an intelligent vehicle, wherein the double-motor steer-by-wire system of the intelligent vehicle comprises a steering wheel corner sensor, a vehicle speed sensor, a variable transmission ratio module and a steering execution module; a steering motor A and a steering motor B in a steering execution module are controlled by a corner ring and a current ring in a double closed loop mode, wherein the corner ring is controlled by a second-order auto-disturbance-rejection controller, and the current ring is controlled by a sliding mode controller, so that the tracking performance of the dual-motor steer-by-wire system is enhanced; in addition, a cross coupling synchronous control structure is adopted between the steering motor A and the steering motor B, the actual rotation angle difference of the steering motor A and the steering motor B is acquired, and a compensation current signal obtained by a synchronous controller is transmitted to current loops of the steering motor A and the steering motor B, so that the rotation angle inconsistency between the steering motor A and the steering motor B is eliminated, and the synchronization performance of the dual-motor steer-by-wire system is enhanced.)

1. A tracking and synchronous control method for a double-motor steer-by-wire system of an intelligent vehicle comprises a steering wheel corner sensor, a vehicle speed sensor, a variable transmission ratio module and a steering execution module;

the steering wheel angle sensor is used for acquiring a steering wheel angle signal and transmitting the steering wheel angle signal to the variable transmission ratio module;

the speed sensor is used for acquiring a speed signal of the intelligent vehicle and transmitting the speed signal to the variable transmission ratio module;

the transmission ratio changing module is used for calculating target rotation angles of two steering motors of the intelligent vehicle according to the obtained steering wheel rotation angle signal and the obtained vehicle speed signal and transmitting the target rotation angles to the steering execution module;

the steering execution module comprises a steering motor A, a speed reducer A, a transmission gear A, a steering motor B, a speed reducer B, a transmission gear B, a rack, a left steering tie rod and a right steering tie rod, wherein the steering motor A is connected with a rotating shaft of the transmission gear A through the speed reducer A, and the steering motor B is connected with a rotating shaft of the transmission gear B through the speed reducer B; the transmission gear A and the transmission gear B are meshed with the rack; the left end and the right end of the rack are fixedly connected with the left steering tie rod and the right steering tie rod respectively; the left steering tie rod and the right steering tie rod are respectively and correspondingly connected with a left steering wheel and a right steering wheel of the intelligent vehicle; the types of the steering motor A and the steering motor B are the same;

the method is characterized in that the tracking and synchronous control method of the dual-motor steer-by-wire system of the intelligent vehicle comprises the following processes:

the steering motor A and the steering motor B are controlled by a corner ring and a current ring in a double closed loop mode, wherein the corner ring is controlled by a second-order active disturbance rejection controller, and the current ring is controlled by a sliding mode controller, so that the tracking performance of the dual-motor steer-by-wire system is enhanced;

the second-order active disturbance rejection controller of the corner loop comprises a third-order extended state observer and a state error feedback control law;

a cross coupling synchronous control structure is adopted between the steering motor A and the steering motor B, the actual rotation angle difference of the steering motor A and the steering motor B is acquired, and a compensation current signal obtained through a synchronous controller is sent to current loops of the steering motor A and the steering motor B, so that the rotation angle inconsistency between the steering motor A and the steering motor B is eliminated, and the synchronization performance of the dual-motor steer-by-wire system is enhanced.

2. The tracking and synchronous control method of the intelligent vehicle double-motor steer-by-wire system according to claim 1, wherein the establishment of the third order extended state observer of the corner ring second order active disturbance rejection controller comprises the following steps:

step A.1), establishing a steering motor kinematic equation:

wherein J is moment of inertia; b is the viscous friction coefficient; k_tIs a torque coefficient; t is_LIs the load torque; theta is the rotation angle of the motor; i.e. i_aIs the current of the motor;

step A.2), writing a steering motor kinematic equation into a standard form of second-order active disturbance rejection control:

in the formula, f is the total disturbance of the system corner ring;respectively, a torque coefficient K of a counter-steering motor_tEstimation of the moment of inertia J; y is the rotation angle of the motor; b₀An estimate of the system control gain; u is the controller output;

step a.3), defining state variables:

step a.4), writing equation (2) into state space form:

in the formula (I), the compound is shown in the specification,is a state variable of the system and is,C＝[1 0 0]，D＝[0 0 0]，F＝[0 0 0]；

step A.5), establishing a third-order extended state observer to estimate the total disturbance of the system:

wherein z is [ z ]₁,z₂,z₃]^TIs a state variable of the extended observer; l ═ beta₁ β₂ β₃]^TIs an observation gain matrix;

step A.6), substituting A, B, L and C into a formula (5) to obtain a state space form of the third-order extended state observer:

step a.7), equation (5) is simplified to obtain:

step a.8), subtracting equation (7) from equation (4):

step a.9), defining two system state variable errors as x-z ═ e, equation (8) is rewritten as:

step A.10), the matrix A-LC is stabilized with e → 0, thus enabling z → x, and the matrix A-LC is stabilized provided that the roots of the characteristic polynomials have negative real parts, the characteristic polynomials of the matrix A-LC being:

in the formula, s is Laplace operator;

step A.11), establishing a characteristic equation which has stable performance and can provide a stable transition process, wherein the expression is as follows:

(s+ω₀)³＝s³+3ω₀s²+3ω₀ ²s+ω₀ ³ (11)

in the formula, ω₀Is the observer bandwidth;

step A.12), combining equations (10) and (11) to obtain β₁＝3ω₀、β₂＝3ω₀ ²、β₃＝ω₀ ³Thus, the third order extended state observer is:

3. the tracking and synchronous control method of the intelligent vehicle double-motor steer-by-wire system according to claim 1, wherein the establishment of the state error feedback control law of the corner loop second-order active disturbance rejection controller comprises the following steps:

step B.1), the state error feedback control law is as follows:

in the formula, k_p、k_dProportional control gain and differential control gain respectively; r is the reference input of the system, u is the controller output, u is the reference input of the system₀Is the output of the state error feedback control law;

step B.2), the three-order extended state observer meets the following conditions:

step b.3), combining equations (2), (13), (14) to obtain:

step b.4), laplace transform of equation (15) yields:

step b.5), rewrite equation (16) into the transfer function form:

step B.6), according to the pole allocation method, the pole of the equation (17) is allocated to the closed loop bandwidth omega_cThe method comprises the following steps:

step B.7), according to equation (17) and equation (18), we getk_d＝2ω_cTherefore, the state error feedback control law is:

4. the tracking and synchronous control method of the intelligent vehicle double-motor steer-by-wire system according to claim 1, wherein the compensation current calculation method of the synchronous controller is as follows:

i′＝k(θ₁-θ₂) (20)

in the formula, theta₁、θ₂Actual turning angles of a steering motor A and a steering motor B are respectively; i' being synchronous controlThe compensation current output by the converter.

Technical Field

The invention relates to the field of automobile auxiliary driving, in particular to a tracking and synchronous control method for a dual-motor steer-by-wire system of an intelligent automobile.

Background

The steer-by-wire eliminates partial mechanical connection between a steering wheel and wheels, and realizes the decoupling of the force transmission characteristic and the angular transmission characteristic of the steering system instead of electronic connection. However, the conventional steer-by-wire system only has one steering motor, the electronic connection system has reliability and safety problems, and how to enhance the reliability and safety of the steer-by-wire system is a problem which needs to be solved urgently in the research field of the steer-by-wire system.

The dual-motor steer-by-wire system adopting the two steering motors can improve the reliability and safety of the steering system from hardware, and once one motor fails, the other motor can normally complete a steering command. In addition, the dual-motor steer-by-wire system can reduce the load of a single motor, thereby improving the service life of the steering motor.

However, the dual-motor steer-by-wire system has the characteristics of strong coupling, nonlinearity, multivariable and the like, and due to factors such as load disturbance, parameter perturbation, model mismatch and the like, the motors have the problems of serious tracking and poor synchronization, so that the steering efficiency, and the service lives of the steering motors and the steering gear are influenced. There is a need to enhance the dual motor steer-by-wire system tracking control and synchronization control.

Disclosure of Invention

The invention aims to solve the technical problem of providing a tracking and synchronous control method of a dual-motor steer-by-wire system of an intelligent vehicle aiming at the defects involved in the background technology.

The invention adopts the following technical scheme for solving the technical problems:

a tracking and synchronous control method for a double-motor steer-by-wire system of an intelligent vehicle comprises a steering wheel corner sensor, a vehicle speed sensor, a variable transmission ratio module and a steering execution module;

the steering wheel angle sensor is used for acquiring a steering wheel angle signal and transmitting the steering wheel angle signal to the variable transmission ratio module;

the speed sensor is used for acquiring a speed signal of the intelligent vehicle and transmitting the speed signal to the variable transmission ratio module;

the transmission ratio changing module is used for calculating target rotation angles of two steering motors of the intelligent vehicle according to the obtained steering wheel rotation angle signal and the obtained vehicle speed signal and transmitting the target rotation angles to the steering execution module;

the steering execution module comprises a steering motor A, a speed reducer A, a transmission gear A, a steering motor B, a speed reducer B, a transmission gear B, a rack, a left steering tie rod and a right steering tie rod, wherein the steering motor A is connected with a rotating shaft of the transmission gear A through the speed reducer A, and the steering motor B is connected with a rotating shaft of the transmission gear B through the speed reducer B; the transmission gear A and the transmission gear B are meshed with the rack; the left end and the right end of the rack are fixedly connected with the left steering tie rod and the right steering tie rod respectively; the left steering tie rod and the right steering tie rod are respectively and correspondingly connected with a left steering wheel and a right steering wheel of the intelligent vehicle; the types of the steering motor A and the steering motor B are the same;

the tracking and synchronous control method of the dual-motor steer-by-wire system of the intelligent vehicle comprises the following steps:

the steering motor A and the steering motor B are controlled by a corner ring and a current ring in a double closed loop mode, wherein the corner ring is controlled by a second-order active disturbance rejection controller, and the current ring is controlled by a sliding mode controller, so that the tracking performance of the dual-motor steer-by-wire system is enhanced;

the second-order active disturbance rejection controller of the corner loop comprises a third-order extended state observer and a state error feedback control law;

a cross coupling synchronous control structure is adopted between the steering motor A and the steering motor B, the actual rotation angle difference of the steering motor A and the steering motor B is acquired, and a compensation current signal obtained through a synchronous controller is sent to current loops of the steering motor A and the steering motor B, so that the rotation angle inconsistency between the steering motor A and the steering motor B is eliminated, and the synchronization performance of the dual-motor steer-by-wire system is enhanced.

As a further optimization scheme of the tracking and synchronous control method of the intelligent vehicle double-motor wire control steering system, the establishment of the third-order extended state observer of the corner ring second-order active disturbance rejection controller comprises the following steps:

step A.1), establishing a steering motor kinematic equation:

wherein J is moment of inertia; b is the viscous friction coefficient; k_tIs a torque coefficient; t is_LIs the load torque; theta is the rotation angle of the motor; i.e. i_aIs the current of the motor;

step A.2), writing a steering motor kinematic equation into a standard form of second-order active disturbance rejection control:

in the formula, f is the total disturbance of the system corner ring;respectively, a torque coefficient K of a counter-steering motor_tEstimation of the moment of inertia J; y is the rotation angle of the motor; b₀An estimate of the system control gain; u is the controller output;

step a.3), defining state variables:

step a.4), writing equation (2) into state space form:

in the formula (I), the compound is shown in the specification,is a state variable of the system and is,C＝[1 0 0]，D＝[0 0 0]，F＝[0 0 0]；

step A.5), establishing a third-order extended state observer to estimate the total disturbance of the system:

wherein z is [ z ]₁,z₂,z₃]^TIs a state variable of the extended observer; l ═ beta₁β₂β₃]^TIs an observation gain matrix;

step A.6), substituting A, B, L and C into a formula (5) to obtain a state space form of the third-order extended state observer:

step a.7), equation (5) is simplified to obtain:

step a.8), subtracting equation (7) from equation (4):

step a.9), defining two system state variable errors as x-z ═ e, equation (8) is rewritten as:

step A.10), the matrix A-LC is stabilized with e → 0, thus enabling z → x, and the matrix A-LC is stabilized provided that the roots of the characteristic polynomials have negative real parts, the characteristic polynomials of the matrix A-LC being:

in the formula, s is Laplace operator;

step A.11), establishing a characteristic equation which has stable performance and can provide a stable transition process, wherein the expression is as follows:

(s+ω₀)³＝s³+3ω₀s²+3ω₀ ²s+ω₀ ³ (11)

in the formula, ω₀Is the observer bandwidth;

step A.12), combining equations (10) and (11) to obtain β₁＝3ω₀、β₂＝3ω₀ ²、β₃＝ω₀ ³Thus, the third order extended state observer is:

as a further optimization scheme of the tracking and synchronous control method of the intelligent vehicle double-motor steer-by-wire system, the establishment of the state error feedback control law of the corner loop second-order active disturbance rejection controller comprises the following steps:

step B.1), the state error feedback control law is as follows:

in the formula, k_p、k_dProportional control gain and differential control gain respectively; r is a parameter of the systemTest input, u is controller output, u₀Is the output of the state error feedback control law;

step B.2), the three-order extended state observer meets the following conditions:

step b.3), combining equations (2), (13), (14) to obtain:

step b.4), laplace transform of equation (15) yields:

step b.5), rewrite equation (16) into the transfer function form:

step B.6), according to the pole allocation method, the pole of the equation (17) is allocated to the closed loop bandwidth omega_cThe method comprises the following steps:

step B.7), according to equation (17) and equation (18), we getk_d＝2ω_cTherefore, the state error feedback control law is:

as a further optimization scheme of the tracking and synchronous control method of the intelligent vehicle double-motor steer-by-wire system, the compensation current calculation method of the synchronous controller comprises the following steps:

i′＝k(θ₁-θ₂) (20)

in the formula, theta₁、θ₂Actual turning angles of a steering motor A and a steering motor B are respectively; i' is the compensation current output by the synchronous controller.

Compared with the prior art, the invention adopting the technical scheme has the following technical effects:

a steering motor A and a steering motor B in a steering execution module are controlled by a corner ring and a current ring in a double closed loop mode, wherein the corner ring is controlled by a second-order active disturbance rejection controller, so that the problems of poor motor tracking performance and poor robustness caused by factors such as external load disturbance, motor parameter perturbation and control model mismatch can be effectively solved; in addition, a cross coupling synchronous control structure is adopted between the steering motor A and the steering motor B, the actual rotation angle difference of the steering motor A and the steering motor B is acquired, and a compensation current signal obtained by a synchronous controller is transmitted to current loops of the steering motor A and the steering motor B, so that the rotation angle inconsistency between the steering motor A and the steering motor B is eliminated, and the synchronization performance between the double motors is enhanced; therefore, the method has wide market application prospect.

Drawings

FIG. 1 is a schematic diagram of tracking and synchronization control of a dual-motor steer-by-wire system of an intelligent vehicle of the present invention;

FIG. 2 is a schematic diagram of the steering motor corner ring second-order active disturbance rejection control and current loop sliding mode control according to the present invention.

Detailed Description

The technical scheme of the invention is further explained in detail by combining the attached drawings:

the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, components are exaggerated for clarity.

The invention discloses a tracking and synchronous control method of a double-motor steer-by-wire system of an intelligent vehicle, wherein the double-motor steer-by-wire system of the intelligent vehicle comprises a steering wheel corner sensor, a vehicle speed sensor, a variable transmission ratio module and a steering execution module;

the steering wheel angle sensor is used for acquiring a steering wheel angle signal and transmitting the steering wheel angle signal to the variable transmission ratio module;

the speed sensor is used for acquiring a speed signal of the intelligent vehicle and transmitting the speed signal to the variable transmission ratio module;

the transmission ratio changing module is used for calculating target rotation angles of two steering motors of the intelligent vehicle according to the obtained steering wheel rotation angle signal and the obtained vehicle speed signal and transmitting the target rotation angles to the steering execution module;

the steering execution module comprises a steering motor A, a speed reducer A, a transmission gear A, a steering motor B, a speed reducer B, a transmission gear B, a rack, a left steering tie rod and a right steering tie rod, wherein the steering motor A is connected with a rotating shaft of the transmission gear A through the speed reducer A, and the steering motor B is connected with a rotating shaft of the transmission gear B through the speed reducer B; the transmission gear A and the transmission gear B are meshed with the rack; the left end and the right end of the rack are fixedly connected with the left steering tie rod and the right steering tie rod respectively; the left steering tie rod and the right steering tie rod are respectively and correspondingly connected with a left steering wheel and a right steering wheel of the intelligent vehicle; the types of the steering motor A and the steering motor B are the same;

as shown in fig. 1 and 2, the tracking and synchronization control method for the dual-motor steer-by-wire system of the intelligent vehicle comprises the following steps:

the tracking and synchronous control method of the dual-motor steer-by-wire system of the intelligent vehicle comprises the following steps:

the steering motor A and the steering motor B are controlled by a corner ring and a current ring in a double closed loop mode, wherein the corner ring is controlled by a second-order active disturbance rejection controller, and the current ring is controlled by a sliding mode controller, so that the tracking performance of the dual-motor steer-by-wire system is enhanced;

the second-order active disturbance rejection controller of the corner loop comprises a third-order extended state observer and a state error feedback control law;

a cross coupling synchronous control structure is adopted between the steering motor A and the steering motor B, the actual rotation angle difference of the steering motor A and the steering motor B is acquired, and a compensation current signal obtained through a synchronous controller is sent to current loops of the steering motor A and the steering motor B, so that the rotation angle inconsistency between the steering motor A and the steering motor B is eliminated, and the synchronization performance of the dual-motor steer-by-wire system is enhanced.

In FIGS. 1 and 2, [ theta ] is_swIs the steering wheel angle; theta^*The reference rotation angles of a steering motor A and a steering motor B are obtained; v is the vehicle speed; theta₁Is the actual turning angle of a steering motor A; theta₂The actual rotation degree of the steering motor B is obtained; i.e. i₁Is the actual current of the steering motor A; i.e. i₂Is the actual current of the steering motor B; i. the compensating current output by the synchronous controller; delta_fIs a wheel corner; t is_L1Is the load torque of steering motor a; t is_L2Is the load torque of steering motor B; u. of_d1Is the input voltage of the steering motor A; u. of_d2In the diagram of the input voltage of the steering motor B, J is the moment of inertia; b is the viscous friction coefficient; k_tIs a torque coefficient; k_eIs the back electromotive force coefficient; omega is the angular speed of the motor; r is a stator resistor; l is the equivalent inductance of the stator winding; i.e. i_aIs the motor current; t is_LIs the load torque; theta is the rotation angle of the motor; z is a radical of₁,z₂,z₃Is a state variable of the extended observer;an estimate of the system control gain;for steering motor torque coefficient K_tAn estimated value of (d);is an estimate of the moment of inertia J.

The establishment of the third-order extended state observer of the second-order active disturbance rejection controller of the corner loop comprises the following steps:

step A.1), establishing a steering motor kinematic equation:

wherein J is moment of inertia; b is the viscous friction coefficient; k_tIs a torque coefficient; t is_LIs the load torque; theta is the rotation angle of the motor; i.e. i_aIs the current of the motor;

step A.2), writing a steering motor kinematic equation into a standard form of second-order active disturbance rejection control:

in the formula, f is the total disturbance of the system corner ring;respectively, a torque coefficient K of a counter-steering motor_tEstimation of the moment of inertia J; y is the rotation angle of the motor; b₀An estimate of the system control gain; u is the controller output;

step a.3), defining state variables:

step a.4), writing equation (2) into state space form:

in the formula (I), the compound is shown in the specification,is a state variable of the system and is,C＝[1 0 0]，D＝[0 0 0]，F＝[0 0 0]；

step A.5), establishing a third-order extended state observer to estimate the total disturbance of the system:

wherein z is [ z ]₁,z₂,z₃]^TIs a state variable of the extended observer; l ═ beta₁ β₂ β₃]^TIs an observation gain matrix;

step A.6), substituting A, B, L and C into a formula (5) to obtain a state space form of the third-order extended state observer:

step a.7), equation (5) is simplified to obtain:

step a.8), subtracting equation (7) from equation (4):

step a.9), defining two system state variable errors as x-z ═ e, equation (8) is rewritten as:

step A.10), the matrix A-LC is stabilized with e → 0, thus enabling z → x, and the matrix A-LC is stabilized provided that the roots of the characteristic polynomials have negative real parts, the characteristic polynomials of the matrix A-LC being:

in the formula, s is Laplace operator;

step A.11), establishing a characteristic equation which has stable performance and can provide a stable transition process, wherein the expression is as follows:

(s+ω₀)³＝s³+3ω₀s²+3ω₀ ²s+ω₀ ³ (11)

in the formula, ω₀Is the observer bandwidth;

step A.12), combining equations (10) and (11) to obtain β₁＝3ω₀、β₂＝3ω₀ ²、β₃＝ω₀ ³Thus, the third order extended state observer is:

the establishment of the state error feedback control law of the second-order active disturbance rejection controller of the corner loop comprises the following steps:

step B.1), the state error feedback control law is as follows:

in the formula, k_p、k_dProportional control gain and differential control gain respectively; r is the reference input of the system, u is the controller output, u is the reference input of the system₀Is the output of the state error feedback control law;

step B.2), the three-order extended state observer meets the following conditions:

step b.3), combining equations (2), (13), (14) to obtain:

step b.4), laplace transform of equation (15) yields:

step b.5), rewrite equation (16) into the transfer function form:

step B.6), according to the pole allocation method, the pole of the equation (17) is allocated to the closed loop bandwidth omega_cThe method comprises the following steps:

step B.7), according to equation (17) and equation (18), we getk_d＝2ω_cTherefore, the state error feedback control law is:

the compensation current calculation method of the synchronous controller comprises the following steps:

i′＝k(θ₁-θ₂) (20)

in the formula, theta₁、θ₂Actual turning angles of a steering motor A and a steering motor B are respectively; i' is the compensation current output by the synchronous controller.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only illustrative of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.