CN111674457B - Active front wheel steering system based on driver characteristics and control method thereof - Google Patents

Abstract

The invention discloses an active front wheel steering system based on driver characteristics and a control method thereof. The system comprises: a steering wheel, a steering column assembly, a double-row planetary gear mechanism, a double-motor steering execution device, and a steering control unit; The steering wheel is connected to a steering column assembly, and the steering column assembly includes: an upper steering column, a torque sensor and a rotation angle sensor; the force input by the steering wheel acts on the double-row planetary wheel structure through the upper steering column, The torque sensor and the rotation angle sensor are respectively fixedly installed on the upper steering column; the present invention performs individualized stability control for different types of drivers, satisfies the driving demands of different types of drivers, and can reduce the control output of the system and improve the performance of the system. Turn to economics.

Description

Active Front Wheel Steering System and Control Method Based on Driver Characteristics

technical field

The invention belongs to the technical field of automobile steering systems, and specifically refers to an active front wheel steering system based on driver characteristics and an individualized control method thereof.

Background technique

As one of the key systems of the car, the steering system directly determines the comfort, handling stability and active safety of the car. Active front wheel steering can control the displacement transmission characteristics of the steering system, and obtain ideal steering characteristics through variable transmission ratio and active steering intervention control, so as to improve the steering stability and active driving safety of the car.

In the existing active front wheel steering technology, a Chinese invention patent application No. CN201710291498.5 discloses a steering stability control system and a control method thereof. The double-row planetary mechanism is used to superimpose the additional rotation angle to the steering system, and based on the improvement The robust control method optimized by genetic algorithm controls the additional turning angle, which effectively improves the robustness of the steering system and the handling stability of the vehicle. However, the above technologies only study the influence of the steering system itself on the stability of the vehicle, and do not consider the influence of the driver's operation on the stability of the vehicle. Chinese Patent Application No. CN201910592489.9 discloses a steering control system based on driver characteristics and a control method thereof. In steering control, the time-varying characteristics of the driver are considered, that is, different periods or different road conditions will cause the driver's When the driving characteristics change, the multi-joint controller is used to realize the robust control of different driver characteristics, which ensures the economy of the steering system and improves the stability of the vehicle. However, the above technologies only consider changes in driver characteristics in different periods and under different road conditions, and do not consider that different types of drivers also have different driving characteristics; therefore, the above technologies all have certain limitations.

In the existing active steering control, most of them only study the control of the steering system itself, and seldom consider the influence of the driver on the steering control. Due to the differences in the ability of different types of drivers to control the vehicle, the novice driver has weaker ability to control the vehicle and is more likely to lose stability during driving, which puts forward higher requirements for the control of the steering system; For skilled drivers, they need to reduce the intervention of the control system due to their strong vehicle handling ability and the pursuit of driving pleasure; general drivers are in the middle. Different types of drivers have different driving characteristics, and thus put forward different control requirements for the control of the steering system. Therefore, it is of great research significance to carry out personalized control for the driving characteristics of different types of drivers to meet the driving needs of different types of drivers.

SUMMARY OF THE INVENTION

In view of the above-mentioned deficiencies of the prior art, the purpose of the present invention is to provide an active front wheel steering system based on driver characteristics and a control method thereof, so as to carry out individualized control according to the driving characteristics of different types of drivers, and ensure that the vehicle Under the premise of stable driving, it can meet the driving needs of different types of drivers.

For achieving the above object, the technical scheme adopted in the present invention is as follows:

An active front wheel steering system based on driver characteristics of the present invention includes: a steering wheel, a steering column assembly, a double-row planetary gear mechanism, a dual-motor steering execution device, and a steering control unit; wherein,

The steering wheel is connected to a steering column assembly, and the steering column assembly includes: an upper steering column, a torque sensor and a rotation angle sensor; the force input by the steering wheel acts on the double-row planetary wheel structure through the upper steering column, A torque sensor and a rotation angle sensor are respectively fixedly installed on the upper steering column;

The dual-motor steering execution device includes: a corner motor module, a booster motor module, a steering tie rod, a steering trapezoid and wheels;

The corner motor module includes: a corner motor, a worm gear, a lower steering column and a ball screw; the output end of the corner motor is connected to the nut of the ball screw through the worm gear, the double-row planetary gear mechanism, and the lower steering column in turn; the ball screw The two ends of the screw rod of the rod are axially and fixedly connected with the coaxial line of the steering tie rod; the rotary motion output by the corner motor is converted into the rotary motion of the lower steering column through the worm gear and the double-row planetary gear mechanism, and the rotary motion of the lower steering column It is converted into the displacement movement of the steering tie rod through the ball screw; the steering tie rod is connected to the wheel through the steering trapezoid;

The booster motor module includes: booster motor, booster motor output shaft and deceleration mechanism; deceleration mechanism includes: pinion, belt, large gear; the pinion is axially fixed on the booster motor output shaft, and the belt connects the pinion and the bullion, the The gear is internally threaded and is sleeved on the ball screw in the axial direction; the output shaft of the power assist motor is arranged in parallel with the steering tie rod, and is connected to the ball screw through the deceleration mechanism; the rotational motion of the power motor output shaft is converted into the pinion Rotational motion, the rotational motion of the pinion is converted into the rotational motion of the large gear through the belt, and the rotational motion of the large gear is converted into the displacement motion of the tie rod through the ball screw;

The steering control unit includes: a main controller and other state units of the vehicle; the input end of the main controller is connected to the above-mentioned sensors, and obtains the torque signal and the angle signal; the other state units of the vehicle provide the main controller with the information of the current vehicle state. Path deviation signal, yaw angular velocity signal, centroid side-slip angle signal, vehicle speed signal, ground interference signal and lateral wind interference signal; the output end of the main controller is connected to the corner motor and the booster motor.

Further, the displacement generated by the ball screw driven by the nut of the ball screw and the displacement generated by the rotation of the large gear driven by the ball screw are superimposed on the steering tie rod, thereby driving the steering trapezoid and the wheel to complete the steering action.

Further, the double-row planetary gear mechanism includes: an upper-row planetary gear train, a lower-row planetary gear train and a planet carrier; the double-row planetary gear mechanism connects the upper steering column and the lower steering column, the upper-row planetary gear train, the lower The planetary gear trains of the upper row are all installed on the planet carrier; the planetary gear train of the upper row includes: the upper row of sun gears, the upper row of planetary gears, and the upper row of ring gears; the upper row of sun gears is fixedly connected with the upper steering column, and the upper row of gear rings is fixed Installed on the frame, the upper row planetary gear is installed between the upper row sun gear and the upper row ring gear; the lower row planetary gear train includes: the lower row sun gear, the lower row planetary gear, the lower row gear ring; the lower row sun gear It is fixedly connected with the lower steering column, the lower ring gear is connected to the worm of the worm gear, the lower planetary gear is installed between the lower sun gear and the lower ring gear; the rotational motion transmitted by the worm passes through the lower ring gear, the lower planetary The wheel, planet carrier, and lower sun gear are converted into the rotational motion of the lower steering column.

Further, the main controller includes: an information processing unit, a driver type identification unit, a personalized control unit, and a motor drive unit; the signal processing unit is electrically connected to the above-mentioned sensors, acquires signals collected by each sensor in real time, and simultaneously processes the signals. The unit is electrically connected to the above-mentioned other state units of the vehicle, and obtains other state signals of the vehicle; the driver type identification unit receives the input signal of the information processing unit, judges the type of the current driver, and inputs the identification result to the personalized control unit. The control unit receives the input signal from the driver type identification unit, obtains the current driver type, and outputs commands to the motor drive unit through the on-board communication line. process.

A control method of an active front wheel steering system based on driver characteristics of the present invention, based on the above system, includes the following steps:

1) Receive torque signal, turning angle signal, path deviation signal, yaw rate signal, centroid slip angle signal, vehicle speed signal, ground interference signal and lateral wind interference signal in real time, and obtain the current driver's operation signal through calculation;

2) Calculate the type of the current driver according to the current driver's operation signal obtained above;

3) According to the driver type obtained above, calculate the ideal yaw angular velocity of the vehicle, take the error between the actual yaw angular velocity of the vehicle and the rational yaw angular velocity as the control amount, and calculate the required output angle of the corner motor and the required output of the booster motor. According to the personalized control instructions, the drive current of the corner motor and the drive current of the booster motor are calculated, the control signal of the corner motor and the control signal of the booster motor are output, and the corner motor and the booster motor are driven to work;

4) The additional rotation angle output by the corner motor is converted into the rotation angle of the lower steering column through the double-row planetary gear mechanism, and the rotation angle of the lower steering column is converted into the displacement of the steering tie rod through the ball screw; The reduction mechanism acts on the ball screw and is converted into the displacement of the steering tie rod; the displacement generated by the nut of the ball screw driven by the ball screw and the displacement generated by the ball screw driven by the rotation of the large gear of the reduction mechanism are carried out on the steering tie rod. Superimpose and output to steering trapezoid and wheels to complete steering control.

Further, the identification of the driver type in the step 2) specifically includes the following steps:

21) Divide the drivers into skilled, general, and novice types. Skilled drivers have rich driving experience, relaxed mental state, quicker response during driving, gentle steering of the steering wheel, and a small steering wheel angle, and the ability to track the road is better. Strong; novice drivers are prone to nervousness during driving, resulting in overreaction, resulting in sharp steering wheel steering and too large steering wheel angle, and poor road tracking effect; general drivers are in between these two;

22) Quantify the proficiency of the driver in manipulating the vehicle, and obtain the proficiency p, which is expressed as:

In the formula: Y _d is the ideal lateral displacement, Y is the actual lateral displacement, θ _sw is the steering wheel angle, k _p1 , k _p2 , and k _p3 are proportional coefficients, k _p1 + k _p2 + k _p3 =1; t is the driving time;

23) The proficiency _p is obtained by _weighting the mean square value of the road tracking error, the mean square value of the steering _wheel angle and the mean square value of the steering wheel angle derivative. Ideal driver type classification method; take k _p1 =0.35, k _p2 =0.35, k _p3 =0.3 respectively;

24) According to the operation signal of the current driver, obtain the ideal lateral displacement Y _d , the actual lateral displacement Y, the steering wheel angle θ _sw , and calculate the proficiency p of the current driver; when the proficiency p is between 0 and 0.47, The current driver is a skilled driver; when the proficiency p is between 0.47 and 0.80, the current driver is a general driver; when the proficiency p is greater than 0.80, the current driver is a novice driver;

25) Determine the type of the current driver according to the calculated proficiency p.

Further, the ideal yaw rate in the step 3) is calculated by the following formula:

In the _formula : ω _r ^* is the ideal yaw rate, id is the ideal transmission ratio under the steady-state yaw rate gain; u is the vehicle speed, L is the wheelbase of the front and rear axles, K is the stability coefficient, K=m(a/ k ₂ -b/k ₁ )/L ² ; a is the distance from the front axle to the center of mass, b is the distance from the rear axle to the center of mass, and G _sw is the steady-state yaw rate gain, taking G _sw =0.275s ^-1 .

Further, the personalized control instruction in the step 3) specifically includes:

31) Based on H∞ hybrid sensitivity control, the weight function W1 in the H∞ hybrid sensitivity control structure is related to the control performance of the controller. The greater the gain _of the weight function W1, the better the control performance _of the controller. For different types of driving The individualized stability controller selects weighting functions W _1h , W _1m , and W _1l with different gains. The weighting functions W _1h , W _1m , and W _1l represent the weighting functions of three types of drivers, skilled, general, and novice, respectively. ;

32) The weighting function W ₁ selects a low-pass transfer function to suppress external high-frequency interference signals; select W ₁ (s) as a first-order rational function:

33) The parameter γ is used to adjust the gain of W ₁ (s). The parameter γ is positively correlated with the performance of the controller, and the performance of the controller is positively correlated with the control energy; the novice driver has high requirements on the performance of the controller, and the skilled driver has high requirements on the controller performance. The performance requirements of the device are low, and the average driver is in the middle; the gain of the weighting function W _1l meets the driving needs of novice drivers, and the gains of the weighting functions W _1m and W _1h are based on the gain of the weighting function W _1l . Driving needs of general and novice drivers; the selection of weighting functions W _1h , W _1m , W _1l is expressed as:

In the formula: k _1m and k _1h are the scaling factors of the general driver weighting function W _1m and the skilled driver weighting function W _1h , respectively, take k _1m =0.5, k _1h =0.25;

The requirements for control performance are expressed as:

In the formula: S(s) is the sensitivity function, which is the transfer function from the disturbance of the control system to the output; T(s) is the complementary sensitivity function, which is the transfer function from the measurement noise of the control system to the output;

34) According to the type of driver, select the corresponding weighting function, calculate the control output of the steering system, and output an instruction to the motor drive unit.

Further, the personalized stability controller in the step 31) specifically includes:

转向盘转角θ_sw，地面干扰力矩d_r和侧向风干扰F_yw，W_d(s)＝[W_d1(s) W_d2(s) W_d3(s)]是干扰输入加权函数矩阵，W_d1(s)，W_d2(s)和W_d3(s)分别为转向盘转角θ_sw，地面干扰力矩d_r和侧向风干扰F_yw到横摆角速度ω_r的加权函数；G_d(s)＝[G₁(s) G₂(s) G₃(s)]是干扰输入传递函数矩阵，G₁(s)，G₂(s)和G₃(s)分别为转向盘转角θ_sw，地面干扰力矩d_r和侧向风干扰F_yw到横摆角速度ω_r的传递函数；311) The disturbance input of the controller is the ideal yaw rate respectively

Steering wheel angle θ _sw , ground disturbance moment d _r and lateral wind disturbance F _yw , W _d (s)=[W _d1 (s) W _d2 (s) W _d3 (s)] is the disturbance input weighting function matrix, W _d1 (s), W _d2 (s) and W _d3 (s) are the weighting functions of the steering wheel angle θ _sw , the ground disturbance moment d _r and the lateral wind disturbance F _yw to the yaw rate ω _r respectively; G _d (s )=[G ₁ (s) G ₂ (s) G ₃ (s)] is the interference input transfer function matrix, G ₁ (s), G ₂ (s) and G ₃ (s) are the steering wheel angle θ _sw , respectively , the transfer function of ground disturbance moment d _r and lateral wind disturbance F _yw to yaw rate ω _r ;

312) The controller has two control outputs z ₁ and z ₂ , where z ₁ represents the target tracking performance and interference suppression performance of the control system, z ₂ represents the robust stability and noise suppression performance of the control system; W ₁ and W ₂ respectively The weighting function representing the two control performances; wherein the weighting function W ₁ is composed of three sub-weighting functions W _1h , W _1m , and W _1l , W _1h , W _1m , and W _1l represent the three categories of skilled, general and novice, respectively The driver's weighting function.

Beneficial effects of the present invention:

The present invention can better distinguish different types of drivers, so as to study the driving characteristics of different types of drivers;

The invention considers the driving characteristics of different types of drivers, and designs different weighting functions for different types of drivers based on the control characteristics of the weighting function in the H∞ hybrid sensitivity control. Different types of drivers can carry out personalized stability control to meet the driving needs of different types of drivers, and can reduce the control output of the system and improve the steering economy.

Description of drawings

Fig. 1 is the principle structure block diagram of the system of the present invention;

Fig. 2 is the structure principle diagram of double-row planetary gear mechanism of the present invention;

Fig. 3 is the individualized control principle diagram based on the driver characteristic of the present invention;

Fig. 4 is the flow chart of the control method of the present invention;

5 is a schematic structural diagram of the personalized H∞ stability controller of the present invention;

In the figure, 1-steering wheel, 2-torque sensor, 3-rotation angle sensor, 4-upper steering column, 5-worm gear, 6-double-row planetary gear mechanism, 7-lower steering column, 8-nut, 9-wheel, 10-steering trapezoid, 11-steering tie rod, 12-ball screw, 13-reduction mechanism, 14-assist motor output shaft, 15-assist motor, 16-corner motor, 17-main controller, 18 -Vehicle other status unit, 19-upper ring gear, 20-upper planetary gear, 21-planet carrier, 22-lower planetary gear, 23-worm, 24-lower ring gear, 25-lower sun gear, 26 - the upper row of sun gear;

A-path deviation signal, B-yaw rate signal, C-centroid side slip angle signal, D-vehicle speed signal, E-ground disturbance signal, F-cross wind disturbance signal, M-torque signal, N-rotation angle signal , G-angle motor control signal, H-assist motor control signal.

Detailed ways

In order to facilitate the understanding of those skilled in the art, the present invention will be further described below with reference to the embodiments and the accompanying drawings, and the contents mentioned in the embodiments are not intended to limit the present invention.

1, an active front wheel steering system based on driver characteristics of the present invention includes: a steering wheel 1, a steering column assembly, a double-row planetary gear mechanism, a dual-motor steering actuator, and a steering control unit; in,

The steering wheel 1 is connected to a steering column assembly, and the steering column assembly includes: an upper steering column 4, a torque sensor 2 and a rotation angle sensor 3; The double-row planetary gear structure 6, the torque sensor 2 and the rotation angle sensor 3 are respectively fixedly installed on the upper steering column 4;

The dual-motor steering execution device includes: a corner motor module, a booster motor module, a steering tie rod 11 , a steering trapezoid 10 and a wheel 9 ;

The corner motor module includes: a corner motor 16, a worm gear 5, a lower steering column 7 and a ball screw 12; the output end of the corner motor 16 is connected to the The nut 8 of the ball screw 12; the two ends of the screw of the ball screw 12 are fixedly connected to the steering rod 11 coaxially and axially; the rotary motion output by the corner motor 16 is converted into The rotational movement of the lower steering column 7, the rotational movement of the lower steering column 7 is converted into the displacement movement of the steering tie rod 11 through the ball screw 12; the steering tie rod 11 is connected to the wheel 9 through the steering trapezoid 10;

The displacement generated by the ball screw driven by the nut of the ball screw and the displacement generated by the rotation of the large gear driven by the ball screw are superimposed on the steering tie rod, thereby driving the steering trapezoid and the wheel to complete the steering action.

The booster motor module includes: booster motor 15, booster motor output shaft 14 and deceleration mechanism 13; the deceleration mechanism includes: a pinion, a belt, and a large gear; the pinion is axially fixed on the booster motor output shaft, and the belt connects the pinion and the larger gear. The gear, the large gear is internally threaded, and is sleeved on the ball screw 12 in the axial direction; the output shaft 14 of the power assist motor is arranged in parallel with the steering tie rod 11, and is connected to the ball screw 12 through the reduction mechanism 13; the output shaft of the power assist motor The rotational motion of 14 is converted into the rotational motion of the pinion, the rotational motion of the pinion is converted into the rotational motion of the large gear through the belt, and the rotational motion of the large gear is converted into the displacement motion of the tie rod 11 through the ball screw 12;

The steering control unit includes: a main controller 17 and other state units 18 of the vehicle; the input end of the main controller 17 is connected to the above sensors, and obtains the torque signal M and the angle signal N; the other state unit 18 of the vehicle is the main control unit The controller 17 provides the path deviation signal A, the yaw rate signal B, the center of mass slip angle signal C, the vehicle speed signal D, the ground disturbance signal E and the lateral wind disturbance signal F of the current vehicle state; the output end of the main controller 17 is connected to the corner Motor 16 and booster motor 15 .

In addition, as shown in FIG. 2 , the double-row planetary gear mechanism includes: an upper-row planetary gear train, a lower-row planetary gear train and a planet carrier 21 ; the double-row planetary gear mechanism connects the upper steering column 4 and the lower steering column 7 , the upper row planetary gear train and the lower row planetary gear train are installed on the planet carrier 21; the upper row planetary gear train includes: the upper row sun gear 26, the upper row planetary gear 20, the upper row gear ring 19; the upper row sun gear 26 It is fixedly connected with the upper steering column 4, the upper row gear ring 19 is fixedly installed on the frame, the upper row planetary gear 20 is installed between the upper row sun gear 26 and the upper row gear ring gear 19; the lower row planetary gear train includes: The row of sun gears 25, the lower row of planetary gears 22, and the lower row of ring gears 24; the lower row of sun gears 25 are fixedly connected to the lower steering column 7, the lower row of ring gears 24 are connected to the worm of the worm gear, and the lower row of planetary gears 22 are installed in the lower row. Between the row of sun gear 25 and the lower row of ring gear 24; the rotational motion transmitted by the worm is converted into the rotational motion of the lower steering column 7 through the lower row of ring gear 24, the lower row of planetary gears 22, the planet carrier 21, and the lower row of the sun gear 25 .

Referring to Figure 3, the main controller includes: an information processing unit, a driver type identification unit, a personalized control unit and a motor drive unit; the signal processing unit is electrically connected to the above-mentioned sensors to obtain real-time signals collected by each sensor, At the same time, the signal processing unit is electrically connected with the other state units of the vehicle to obtain other state signals of the vehicle; the driver type identification unit receives the input signal from the information processing unit, determines the type of the current driver, and inputs the identification result to the personalized control unit , the personalized control unit receives the input signal of the driver type identification unit, obtains the current driver type, and outputs commands to the motor drive unit through the on-board communication line. Action control process.

Referring to Figure 4, a control method of an active front wheel steering system based on driver characteristics of the present invention, based on the above system, includes the following steps:

1) Receive torque signal, corner signal, path deviation signal, yaw rate signal, centroid slip angle signal, vehicle speed signal, ground disturbance signal, and lateral wind disturbance signal in real time, and obtain the current driver's operation signal through calculation;

2) Calculate the type of the current driver according to the current driver's operation signal obtained above;

3) According to the driver type obtained above, calculate the ideal yaw angular velocity of the vehicle, take the error between the actual yaw angular velocity of the vehicle and the rational yaw angular velocity as the control amount, and calculate the required output angle of the corner motor and the required output of the booster motor. According to the personalized control instructions, the drive current of the corner motor and the drive current of the booster motor are calculated, the control signal of the corner motor and the control signal of the booster motor are output, and the corner motor and the booster motor are driven to work;

4) The additional rotation angle output by the corner motor is converted into the rotation angle of the lower steering column through the double-row planetary gear mechanism, and the rotation angle of the lower steering column is converted into the displacement of the steering tie rod through the ball screw; The reduction mechanism acts on the ball screw and is converted into the displacement of the steering tie rod; the displacement generated by the nut of the ball screw driven by the ball screw and the displacement generated by the ball screw driven by the rotation of the large gear of the reduction mechanism are carried out on the steering tie rod. Superimpose and output to steering trapezoid and wheels to complete steering control.

The identification of the driver type in the step 2) specifically includes the following steps:

21) Divide the drivers into skilled, general, and novice types. Skilled drivers have rich driving experience, relaxed mental state, quicker response during driving, gentle steering of the steering wheel, and a small steering wheel angle, and the ability to track the road is better. Strong; novice drivers are prone to nervousness during driving, resulting in overreaction, resulting in sharp steering wheel steering and too large steering wheel angle, and poor road tracking effect; general drivers are in between these two;

22) Quantify the proficiency of the driver in manipulating the vehicle, and obtain the proficiency p, which is expressed as:

In the formula: Y _d is the ideal lateral displacement, Y is the actual lateral displacement, θ _sw is the steering wheel angle, k _p1 , k _p2 , and k _p3 are proportional coefficients, k _p1 + k _p2 + k _p3 =1; t is the driving time;

23) Proficiency p is weighted by the mean square value of the road tracking error, the mean square value of the steering wheel angle and the mean square value of the steering wheel angle derivative, taking into account the driver's road tracking ability, the size of the steering wheel angle and the speed of steering the steering wheel The influence on the driver's driving proficiency; and the size of the proportional coefficients k _p1 , k _p2 , k _p3 can be adjusted to obtain an ideal driver type classification method; considering that there are some skilled drivers who seek driving pleasure The speed of steering the steering wheel has a weaker influence on the driver’s proficiency than the road tracking ability and the steering wheel angle. Therefore, k _p1 = 0.35, k _p2 = 0.35, and k _p3 = 0.3 respectively;

24) According to the operation signal of the current driver, obtain the ideal lateral displacement Y _d , the actual lateral displacement Y, the steering wheel angle θ _sw , and calculate the proficiency p of the current driver; when the proficiency p is between 0 and 0.47, The current driver is a skilled driver; when the proficiency p is between 0.47 and 0.80, the current driver is a general driver; when the proficiency p is greater than 0.80, the current driver is a novice driver;

25) Determine the type of the current driver according to the calculated proficiency p.

In addition, the ideal yaw rate in the step 3) is calculated by the following formula:

In the _formula : ω _r ^* is the ideal yaw rate, id is the ideal transmission ratio under the steady-state yaw rate gain; u is the vehicle speed, L is the wheelbase of the front and rear axles, K is the stability coefficient, K=m(a/ k ₂ -b/k ₁ )/L ² ; a is the distance from the front axle to the center of mass, b is the distance from the rear axle to the center of mass, and G _sw is the steady-state yaw rate gain, taking G _sw =0.275s ^-1 .

Referring to Figure 5, the personalized control instructions in step 3) specifically include:

31) Based on H∞ hybrid sensitivity control, the weight function W1 in the H∞ hybrid sensitivity control structure is related to the control performance of the controller. The greater the gain _of the weight function W1, the better the control performance _of the controller. For different types of driving The individualized stability controller selects weighting functions W _1h , W _1m , and W _1l with different gains. The weighting functions W _1h , W _1m , and W _1l represent the weighting functions of three types of drivers, skilled, general, and novice, respectively. ;

32) The weighting function W ₁ selects a low-pass transfer function to suppress external high-frequency interference signals; select W ₁ (s) as a first-order rational function:

33) The parameter γ is used to adjust the gain of W ₁ (s). The larger the value of γ, the better the control performance of the control system, and the better the control performance means, the greater the required control energy; different types of drivers There are differences in the requirements for the control performance of the controller. The weaker the driver's ability to control the vehicle, the higher the requirements for the control performance of the controller. The gain of the weighting function W _1l meets the driving needs of novice drivers. The weighting function W _1m and The gain of W _1h is respectively reduced based on the gain of the weighting function W _1l ; the selection of the weighting functions W _1h , W _1m and W _1l is expressed as:

In the formula: k _1m and k _1h are the scaling factors of the general driver weighting function W _1m and the skilled driver weighting function W _1h , respectively, take k _1m =0.5, k _1h =0.25;

The requirements for control performance are expressed as:

In the formula: S(s) is the sensitivity function, which is the transfer function from the disturbance of the control system to the output; T(s) is the complementary sensitivity function, which is the transfer function from the measurement noise of the control system to the output;

34) According to the type of driver, select the corresponding weighting function, calculate the control output of the steering system, and output an instruction to the motor drive unit.

The personalized stability controller in the step 31) specifically includes:

转向盘转角θ_sw，地面干扰力矩d_r和侧向风干扰F_yw，W_d(s)＝[W_d1(s) W_d2(s) W_d3(s)]是干扰输入加权函数矩阵，W_d1(s)，W_d2(s)和W_d3(s)分别为转向盘转角θ_sw，地面干扰力矩d_r和侧向风干扰F_yw到横摆角速度ω_r的加权函数；G_d(s)＝[G₁(s) G₂(s) G₃(s)]是干扰输入传递函数矩阵，G₁(s)，G₂(s)和G₃(s)分别为转向盘转角θ_sw，地面干扰力矩d_r和侧向风干扰F_yw到横摆角速度ω_r的传递函数；311) The disturbance input of the controller is the ideal yaw rate respectively

Steering wheel angle θ _sw , ground disturbance moment d _r and lateral wind disturbance F _yw , W _d (s)=[W _d1 (s) W _d2 (s) W _d3 (s)] is the disturbance input weighting function matrix, W _d1 (s), W _d2 (s) and W _d3 (s) are the weighting functions of the steering wheel angle θ _sw , the ground disturbance moment d _r and the lateral wind disturbance F _yw to the yaw rate ω _r respectively; G _d (s )=[G ₁ (s) G ₂ (s) G ₃ (s)] is the interference input transfer function matrix, G ₁ (s), G ₂ (s) and G ₃ (s) are the steering wheel angle θ _sw , respectively , the transfer function of ground disturbance moment d _r and lateral wind disturbance F _yw to yaw rate ω _r ;

312) The controller has two control outputs z ₁ and z ₂ , where z ₁ represents the target tracking performance and interference suppression performance of the control system, z ₂ represents the robust stability and noise suppression performance of the control system; W ₁ and W ₂ respectively The weighting function representing the two control performances; wherein the weighting function W ₁ is composed of three sub-weighting functions W _1h , W _1m , and W _1l , W _1h , W _1m , and W _1l represent the three categories of skilled, general and novice, respectively The driver's weighting function.

There are many specific application ways of the present invention, and the above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, several improvements can be made. These Improvements should also be considered as the protection scope of the present invention.

Claims (4)

1. A control method of an active front wheel steering system based on driver characteristics, comprising: the double-row planetary gear mechanism comprises a steering wheel, a steering column assembly, a double-row planetary gear mechanism, a double-motor steering executing device and a steering control unit;

the steering wheel is connected with a steering column assembly, and the steering column assembly comprises: an upper steering column, a torque sensor and a corner sensor; the acting force input by the steering wheel acts on the double-row planetary wheel structure through the upper steering column, and the torque sensor and the corner sensor are fixedly mounted on the upper steering column respectively;

the dual-motor steering actuator includes: the steering angle motor module, the power-assisted motor module, the steering tie rod, the steering trapezoid and the wheels;

the corner motor module includes: the steering mechanism comprises a corner motor, a worm gear, a lower steering column and a ball screw; the output end of the corner motor is connected to a nut of the ball screw through a worm gear, a double-row planetary gear mechanism and a lower steering column in sequence; two ends of a screw rod of the ball screw are fixedly connected with the steering tie rod in a coaxial axial direction; the rotary motion output by the corner motor is converted into rotary motion of the lower steering pipe column through the worm gear and the double-row planet wheel mechanism, and the rotary motion of the lower steering pipe column is converted into displacement motion of the steering tie rod through the ball screw; the tie rods are connected to the wheels through a steering trapezoid;

the assist motor module includes: the power-assisted motor, the output shaft of the power-assisted motor and the speed reducing mechanism; the speed reducing mechanism includes: pinion, belt, bull gear; the small gear is axially fixed on an output shaft of the power-assisted motor, the belt is connected with the small gear and the large gear, and the large gear is internally provided with threads and is axially sleeved on the ball screw; the output shaft of the power-assisted motor is arranged in parallel relative to the steering tie rod and is connected to the ball screw through a speed reducing mechanism; the rotary motion of an output shaft of the power-assisted motor is converted into the rotary motion of a pinion, the rotary motion of the pinion is converted into the rotary motion of a bull gear through a belt, and the rotary motion of the bull gear is converted into the displacement motion of a steering tie rod through a ball screw;

the steering control unit includes: a main controller and other state units of the vehicle; the input end of the main controller is connected with each sensor and acquires a torque signal and a corner signal; the other state units of the vehicle provide a path deviation signal, a yaw rate signal, a mass center side deviation angle signal, a vehicle speed signal, a ground interference signal and a side wind interference signal of the current vehicle state for the main controller; the output end of the main controller is connected with the corner motor and the power-assisted motor;

the method is characterized by comprising the following steps:

1) receiving a torque signal, a corner signal, a path deviation signal, a yaw velocity signal, a mass center yaw angle signal, a vehicle speed signal, a ground interference signal and a lateral wind interference signal in real time, and calculating to obtain a current driver operation signal;

2) calculating the type of the current driver according to the obtained operation signal of the current driver;

3) calculating an ideal yaw rate of the vehicle according to the obtained driver type, calculating a corner required to be output by a corner motor and a power-assisted moment required to be output by a power-assisted motor by taking an error between an actual yaw rate and a rational yaw rate of the vehicle as a control quantity to obtain a corresponding personalized control instruction, calculating a driving current of the corner motor and a driving current of the power-assisted motor according to the personalized control instruction, outputting a control signal of the corner motor and a control signal of the power-assisted motor, and driving the corner motor and the power-assisted motor to work;

4) the additional corner output by the corner motor is converted into a corner of a lower steering pipe column through the double-row planet wheel mechanism, and the corner of the lower steering pipe column is converted into displacement of a steering tie rod through a ball screw; the electromagnetic torque output by the power-assisted motor acts on the ball screw through the speed reducing mechanism and is converted into the displacement of the steering tie rod; the nut of the ball screw drives the ball screw to generate displacement, and the large gear of the speed reducing mechanism rotates to drive the ball screw to generate displacement, the displacement is superposed on the steering tie rod and is output to the steering trapezoid and the wheels, and the steering control is completed;

the identification of the driver type in the step 2) specifically comprises the following steps:

21) dividing drivers into a proficiency type, a general type and a new hand type;

22) quantifying the proficiency of the driver in maneuvering the vehicle yields a proficiency p, which is expressed as:

in the formula: y is_dFor ideal lateral displacement, Y is the actual lateral displacement, θ_swTo the steering wheel angle, k_p1，k_p2，k_p3Are all proportionality coefficients, k_p1+k_p2+k_p31 is ═ 1; t is the travel time;

23) the proficiency p is obtained by weighting the mean square value of the road tracking error, the mean square value of the steering wheel angle and the mean square value of the steering wheel angle derivative, and is obtained by adjusting the proportionality coefficient k_p1，k_p2，k_p3To obtain an ideal driver type classification method; respectively take k_p1＝0.35，k_p2＝0.35，k_p3＝0.3；

24) Obtaining ideal lateral displacement Y according to the current operation signal of the driver_dActual lateral displacement Y and steering wheel angle theta_swCalculating the proficiency p of the current driver; when the proficiency p is between 0 and 0.47, the current driver is a proficient driver; when the proficiency p is between 0.47 and 0.80, the current driver is a general driver; when the proficiency p is greater than 0.80, the current driver is a novice driver;

25) and judging the type of the current driver according to the calculated proficiency p.

2. The control method of an active front wheel steering system based on driver characteristics according to claim 1, characterized in that the ideal yaw rate in step 3) is calculated by the following formula:

in the formula: omega_r ^*Is an ideal yaw rate, i_dIs an ideal transmission ratio under the gain of the steady yaw rate; u is vehicle speed, L is front-rear axle base, K is stability factor, and K is m (a/K)₂-b/k₁)/L²(ii) a a is the distance from the front axle to the center of mass, b is the distance from the rear axle to the center of mass, G_swIs in a steady stateYaw rate gain, taking G_sw＝0.275s^-1。

3. The control method of the active front steering system based on the driver characteristics according to claim 1, wherein the personalized control instruction in the step 3) specifically comprises:

31) based on H infinity mixing sensitivity control, weight function W in H infinity mixing sensitivity control structure₁The weight function W is related to the control performance of the controller₁The larger the gain of (c), the better the control performance of the controller, and for different types of drivers, the personalized stability controller selects a weighting function W with different gains_1h、W_1m、W_1lWeighted function W_1h、W_1m、W_1lWeighting functions respectively representing three types of drivers of proficiency type, general type and novice type;

32) weighting function W₁Selecting a low-pass transfer function to suppress external high-frequency interference signals; selecting W₁(s) is a first order rational function:

33) the parameter gamma is used to adjust W₁(s) gain, parameter γ being positively correlated with controller performance, controller performance being positively correlated with control energy; the new hand type driver has high requirement on the performance of the controller, the skilled driver has low requirement on the performance of the controller, and the common driver is centered; weighting function W_1lThe gain of (A) satisfies the driving requirements of a novice driver, the weighting function W_1mAnd W_1hIs given as a weighting function W_1lThe gains of the drivers are respectively reduced as a reference, and the driving requirements of general drivers and novice drivers are respectively met; weighting function W_1h、W_1m、W_1lIs selected to representComprises the following steps:

in the formula: k is a radical of_1m，k_1hRespectively, a general driver weighting function W_1mAnd a skilled driver weighting function W_1hRespectively take k as the scaling factor of_1m＝0.5，k_1h＝0.25；

The requirements regarding control performance are expressed as:

in the formula: s(s) is a sensitivity function, which is a transfer function from interference of the control system to output; t(s) is a complementary sensitivity function, which is a transfer function from the measured noise to the output of the control system;

34) and selecting a corresponding weighting function according to the type of the driver, calculating the control output of the steering system, and outputting an instruction to the motor driving unit.

4. The control method of an active front steering system based on driver characteristics according to claim 3, characterized in that the personalized stability controller in step 31) specifically comprises:

311) the disturbance input of the controller is respectively the ideal yaw rate

Steering wheel angle theta_swGround disturbance moment d_rAnd side wind interference F_yw，W_d(s)＝[W_d1(s) W_d2(s) W_d3(s)]Is a matrix of interference input weighting functions, W_d1(s)，W_d2(s) and W_d3(s) are respectively steering wheel angle theta_swGround disturbance moment d_rAnd side wind interference F_ywTo yaw angular velocity omega_rA weighting function of (a); g_d(s)＝[G₁(s) G₂(s) G₃(s)]Is a matrix of interference input transfer functions, G₁(s)，G₂(s) and G₃(s) are respectively steering wheel angle theta_swGround disturbance moment d_rAnd side wind interference F_ywTo yaw angular velocity omega_rThe transfer function of (a);

312) the controller has two control outputs z₁And z₂Wherein z is₁Representative of control system target tracking and interference rejection performance, z₂Represents robust stability and noise suppression performance of the control system; w₁And W₂Weighting functions representing the two control performances respectively; wherein the weighting function W₁From W_1h，W_1m，W_1lThree sub-weighting functions, W_1h，W_1m，W_1lRepresenting the weighting functions of three types of drivers, namely a skilled driver, a general driver and a novice driver.

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