CN111674457A - Active front wheel steering system based on driver characteristics and control method thereof - Google Patents
Active front wheel steering system based on driver characteristics and control method thereof Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
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- B62D5/00—Power-assisted or power-driven steering
- B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
- B62D5/0457—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
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- B62D5/0463—Controlling the motor calculating assisting torque from the motor based on driver input
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- B—PERFORMING OPERATIONS; TRANSPORTING
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Abstract
The invention discloses an active front wheel steering system based on driver characteristics and a control method thereof, wherein the system comprises: 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 invention carries out personalized stability control on drivers of different types, meets the driving requirements of the drivers of different types, can reduce the control output of the system and improves the steering economy.
Description
Technical Field
The invention belongs to the technical field of automobile steering systems, and particularly relates to an active front wheel steering system based on driver characteristics and an individualized control method thereof.
Background
The steering system is one of the key systems of the automobile, and directly determines the comfort, the operation stability and the active safety of the automobile. The active front wheel steering can control the displacement transfer characteristic of a steering system, and obtains ideal steering characteristic through variable transmission ratio and active steering intervention control so as to improve the operation stability and driving active safety of the automobile.
In the existing active front wheel steering technology, the Chinese invention patent application No. CN201710291498.5 discloses a steering stability control system and a control method thereof, wherein a double-row planetary mechanism is utilized to superpose an additional steering angle on a steering system, and the additional steering angle is controlled based on a robust control method optimized by an improved genetic algorithm, so that the robustness of the steering system and the steering stability of a vehicle are effectively improved. However, the above-described technology only studies the influence of the steering system itself on the vehicle stability, and does not consider the influence of the operation of the driver on the vehicle stability. Chinese patent application No. CN201910592489.9 discloses a steering control system based on driver characteristics and a control method thereof, wherein the time-varying property of the driver characteristics is considered in the steering control, that is, the driving characteristics of the driver can be changed in different periods or different road conditions, and a multi-combination controller is used to realize robust control of different driver characteristics, thereby improving the stability of the vehicle while ensuring the economy of the steering system. However, the above-mentioned technology only considers the change of the characteristics of the drivers in different periods and under different road conditions, and does not consider that different types of drivers also have different driving characteristics; therefore, the above techniques have certain limitations.
In the existing active steering control, most of the research is only carried out on the control of the steering system, and the influence of the driver on the steering control is rarely considered. Because different types of drivers have different vehicle operating abilities, a novice driver has weaker vehicle operating ability, and the stability of the vehicle is easier to lose in the running process, higher requirements are provided for the control of a steering system; for a skilled driver, the control system needs to be reduced because the driver has stronger vehicle control capability and pursues more driving pleasure; the average driver is in between. Different types of drivers have different driving characteristics and thus impose different control requirements on the control of the steering system. Therefore, the method and the device have important research significance for carrying out personalized control on the driving characteristics of different types of drivers so as to meet the driving requirements of the different types of drivers.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, an object 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 perform personalized control on the driving characteristics of different types of drivers, and meet the driving requirements of different types of drivers on the premise of ensuring the driving stability of the vehicle.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
an active front wheel steering system based on driver characteristics of the present invention includes: 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; wherein,
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.
Furthermore, the nut of the ball screw drives the ball screw to generate displacement, and the large gear rotates to drive the ball screw to generate displacement, which is superposed on the tie rod, so as to drive the steering trapezoid and the wheels to complete steering action.
Further, the double row planetary gear mechanism includes: an upper row of planetary gear trains, a lower row of planetary gear trains and a planet carrier; the double-row planetary gear mechanism is connected with an upper steering column and a lower steering column, and the upper-row planetary gear train and the lower-row planetary gear train are both arranged on the planet carrier; the upper row planetary gear train comprises: an upper row of sun gears, an upper row of planet gears and an upper row of gear rings; the upper row of sun gears is fixedly connected with the upper steering column, the upper row of gear rings is fixedly arranged on the frame, and the upper row of planet gears are arranged between the upper row of sun gears and the upper row of gear rings; the lower-row planetary gear train comprises: a lower-row sun wheel, a lower-row planet wheel and a lower-row gear ring; the lower-row sun gear is fixedly connected with the lower steering column, the lower-row gear ring is connected to a worm of a worm gear, and the lower-row planet gear is arranged between the lower-row sun gear and the lower-row gear ring; the rotary motion transmitted by the worm is converted into the rotary motion of the lower steering pipe column through the lower row of gear rings, the lower row of planet wheels, the planet carrier and the lower row of sun wheels.
Further, the main controller includes: the system comprises an information processing unit, a driver type identification unit, an individualized control unit and a motor driving unit; the signal processing unit is electrically connected with the sensors to acquire signals acquired by the sensors in real time, and is electrically connected with other state units of the vehicle to acquire 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 personalized control unit receives the input signal of the driver type identification unit to obtain the type of the current driver, an instruction is output to the motor drive unit through the vehicle-mounted communication line, the motor drive unit respectively outputs a corner motor control signal and a power-assisted motor control signal, and the control process of the steering action is completed.
The invention relates to a control method of an active front wheel steering system based on driver characteristics, which is based on the system and comprises 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, 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 steering control is completed.
Further, the identifying of the driver type in step 2) specifically includes the following steps:
21) the driver is divided into a proficiency type driver, a general type driver and a new hand type driver, the proficiency type driver has rich driving experience, relaxed psychological state, quicker response in the driving process, smoother steering wheel operation, smaller steering wheel turning angle and stronger road tracking capability; the novice driver is easy to have mental stress in the driving process, so that excessive reaction is caused, the steering wheel is operated sharply, the steering wheel angle is too large, and the road tracking effect is poor; a general driver, between the two;
22) quantifying the proficiency of the driver in maneuvering the vehicle yields a proficiency p, which is expressed as:
in the formula: y isdFor ideal lateral displacement, Y is the actual lateral displacement, θswTo the steering wheel angle, kp1，kp2，kp3Are all proportionality coefficients, kp1+kp2+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 kp1，kp2，kp3To obtain an ideal driver type classification method; respectively take kp1＝0.35，kp2＝0.35，kp3＝0.3；
24) Obtaining ideal lateral displacement Y according to the current operation signal of the driverdActual lateral displacement Y and steering wheel angle thetaswCalculating 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.
Further, the ideal yaw rate in step 3) is calculated by the following formula:
in the formula: omegar *Is an ideal yaw rate, idIs 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, GswFor steady state yaw rate gain, take Gsw＝0.275s-1。
Further, the personalized control instruction in step 3) specifically includes:
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 gains1h、W1m、W1lWeighted function W1h、W1m、W1lWeighting 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 W1lThe gain of (A) satisfies the driving requirements of a novice driver, the weighting function W1mAnd W1hIs given as a weighting function W1lThe 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 W1h、W1m、W1lThe selection of (a) is represented as:
in the formula: k is a radical of1m，k1hRespectively, a general driver weighting function W1mAnd a skilled driver weighting function W1hRespectively take k as the scaling factor of1m＝0.5，k1h＝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.
Further, the personalized stability controller in step 31) specifically includes:
311) the disturbance input of the controller is respectively the ideal yaw rate
Steering wheel angle thetaswGround disturbance moment drAnd side wind interference Fyw，Wd(s)＝[Wd1(s) Wd2(s) Wd3(s)]Is a matrix of interference input weighting functions, Wd1(s)，Wd2(s) and Wd3(s) are respectively steering wheel angle thetaswGround disturbance moment drAnd side wind interference FywTo yaw angular velocity omegarA weighting function of (a); gd(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 thetaswGround disturbance moment drAnd side wind interference FywTo yaw angular velocity omegarThe 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 W1h，W1m，W1lThree sub-weighting functions, W1h，W1m，W1lRespectively generation by generationTable skilled, general and novice driver weighting functions.
The invention has the beneficial effects that:
the invention can better distinguish different types of drivers so as to research the driving characteristics of the drivers of different types;
the invention considers the driving characteristics of different types of drivers, designs different weighting functions aiming at the different types of drivers based on the control characteristics of the weighting functions in the H-infinity mixed sensitivity control, carries out personalized stability control on the different types of drivers on the premise of ensuring the driving stability of the vehicle, meets the driving requirements of the different types of drivers, can reduce the control output of the system and improves the steering economy.
Drawings
FIG. 1 is a block diagram of the schematic architecture of the system of the present invention;
FIG. 2 is a schematic diagram of the structure of the double-row planetary gear mechanism of the present invention;
FIG. 3 is a schematic diagram of the personalized control based on driver characteristics according to the present invention;
FIG. 4 is a flow chart of a control method of the present invention;
FIG. 5 is a schematic diagram of a 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 cross pull rod, 12-ball screw, 13-speed reducing mechanism, 14-power-assisted motor output shaft, 15-power-assisted motor, 16-rotation angle motor, 17-main controller, 18-vehicle other state unit, 19-upper row of gear ring, 20-upper row of planetary gear, 21-planetary carrier, 22-lower row of planetary gear, 23-worm, 24-lower row of gear ring, 25-lower row of sun gear, and 26-upper row of sun gear;
the system comprises an A-path deviation signal, a B-yaw angular velocity signal, a C-mass center side deviation angular signal, a D-vehicle speed signal, an E-ground interference signal, an F-side wind interference signal, an M-torque signal, an N-corner signal, a G-corner motor control signal and an H-power-assisted motor control signal.
Detailed Description
In order to facilitate understanding of those skilled in the art, the present invention will be further described with reference to the following examples and drawings, which are not intended to limit the present invention.
Referring to fig. 1, an active front steering system based on driver characteristics according to the present invention includes: the steering wheel comprises a steering wheel 1, a steering column assembly, a double-row planetary gear mechanism, a double-motor steering executing device and a steering control unit; wherein,
the dual-motor steering actuator includes: the steering angle motor module, the power-assisted motor module, the steering tie rod 11, the steering trapezoid 10 and the wheels 9;
the corner motor module includes: the steering mechanism comprises 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 a nut 8 of the ball screw 12 through a worm gear 5, a double-row planet gear mechanism 6 and a lower steering column 7 in sequence; two ends of the ball screw 12 are axially and fixedly connected with the steering tie rod 11 in a coaxial line; the rotary motion output by the corner motor 16 is converted into the rotary motion of the lower steering column 7 through the worm gear 5 and the double-row planet wheel mechanism 6, and the rotary motion of the lower steering column 7 is converted into the displacement motion of the tie rod 11 through the ball screw 12; the tie rods 11 are connected to the wheels 9 through the steering trapezoids 10;
the nut of the ball screw drives the ball screw to generate displacement, and the large gear rotates to drive the ball screw to generate displacement, so that the displacement is superposed on the tie rod, and the steering trapezoid and the wheels are driven to complete steering action.
The assist motor module includes: the booster motor 15, the booster motor output shaft 14 and the speed reducing mechanism 13; 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, threads are arranged in the large gear, and the large gear is axially sleeved on the ball screw 12; the output shaft 14 of the booster motor is arranged in parallel relative to the tie rod 11 and is connected to the ball screw 12 through a speed reducing mechanism 13; the rotary motion of the output shaft 14 of the booster motor is converted into the rotary motion of a pinion gear, the rotary motion of the pinion gear 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 tie rod 11 through a ball screw 12;
the steering control unit includes: a main controller 17 and other vehicle status units 18; the input end of the main controller 17 is connected with each sensor, and obtains a torque signal M and a corner signal N; the other-vehicle-state unit 18 provides the main controller 17 with a path deviation signal a, a yaw-rate signal B, a centroid yaw-angle signal C, a vehicle-speed signal D, a ground interference signal E and a lateral-wind interference signal F of the current vehicle state; the output end of the main controller 17 is connected with the angle motor 16 and the power-assisted motor 15.
Further, referring to fig. 2, the double row planetary gear mechanism includes: an upper row of planetary gear trains, a lower row of planetary gear trains and a planet carrier 21; the double-row planetary gear mechanism is connected with the upper steering column 4 and the lower steering column 7, and the upper row of planetary gear train and the lower row of planetary gear train are both arranged on the planet carrier 21; the upper row planetary gear train comprises: an upper row sun gear 26, an upper row planet gear 20 and an upper row gear ring 19; the upper row of sun gears 26 is fixedly connected with the upper steering column 4, the upper row of gear rings 19 is fixedly arranged on the frame, and the upper row of planet gears 20 are arranged between the upper row of sun gears 26 and the upper row of gear rings 19; the lower-row planetary gear train comprises: a lower-row sun gear 25, a lower-row planet gear 22 and a lower-row gear ring 24; the lower-row sun gear 25 is fixedly connected with the lower steering column 7, the lower-row gear ring 24 is connected with a worm of a worm gear, and the lower-row planet gear 22 is arranged between the lower-row sun gear 25 and the lower-row gear ring 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 gears 24, the lower row of planet gears 22, the planet carrier 21 and the lower row of sun gears 25.
Referring to fig. 3, the main controller includes: the system comprises an information processing unit, a driver type identification unit, an individualized control unit and a motor driving unit; the signal processing unit is electrically connected with the sensors to acquire signals acquired by the sensors in real time, and is electrically connected with other state units of the vehicle to acquire 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 personalized control unit receives the input signal of the driver type identification unit to obtain the type of the current driver, an instruction is output to the motor drive unit through the vehicle-mounted communication line, the motor drive unit respectively outputs a corner motor control signal and a power-assisted motor control signal, and the control process of the steering action is completed.
Referring to fig. 4, a control method of an active front steering system based on driver characteristics according to the present invention includes the following steps based on the above system:
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, 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 steering control is completed.
The identification of the driver type in the step 2) specifically comprises the following steps:
21) the driver is divided into a proficiency type driver, a general type driver and a new hand type driver, the proficiency type driver has rich driving experience, relaxed psychological state, quicker response in the driving process, smoother steering wheel operation, smaller steering wheel turning angle and stronger road tracking capability; the novice driver is easy to have mental stress in the driving process, so that excessive reaction is caused, the steering wheel is operated sharply, the steering wheel angle is too large, and the road tracking effect is poor; a general driver, between the two;
22) quantifying the proficiency of the driver in maneuvering the vehicle yields a proficiency p, which is expressed as:
in the formula: y isdFor ideal lateral displacement, Y is the actual lateral displacement, θswTo the steering wheel angle, kp1，kp2，kp3Are all proportionality coefficients, kp1+kp2+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 the influence of the road tracking capacity of a driver, the steering wheel angle and the speed of operating the steering wheel on the driving proficiency of the driver is considered; and can be adjusted by adjusting the proportionality coefficient kp1，kp2，kp3To obtain an ideal driver type classification method; considering that there are some drivers who seek driving pleasure among skilled drivers, how fast or slow the steering wheel is manipulated is relatively influenced by the road-following ability and the magnitude of the steering wheel angle on the driver's proficiencyWeak, therefore, take k respectivelyp1＝0.35，kp2＝0.35，kp3＝0.3；
24) Obtaining ideal lateral displacement Y according to the current operation signal of the driverdActual lateral displacement Y and steering wheel angle thetaswCalculating 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.
Further, the ideal yaw rate in step 3) is calculated by the following formula:
in the formula: omegar *Is an ideal yaw rate, idIs 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, GswFor steady state yaw rate gain, take Gsw＝0.275s-1。
Referring to fig. 5, the personalized control instruction in step 3) specifically includes:
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 gains1h、W1m、W1lWeighted function W1h、W1m、W1lWeighting 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), the greater the value of γ, the better the control performance of the control system, and the better the control performance means the greater the control energy required; the requirements of different drivers on the control performance of the controller are different, and the weaker the control capability of the driver on the vehicle, the higher the requirement on the control performance of the controller, the weighting function W1lThe gain of (A) satisfies the driving requirements of a novice driver, the weighting function W1mAnd W1hIs given as a weighting function W1lRespectively reducing the gain of the reference point; weighting function W1h、W1m、W1lThe selection of (a) is represented as:
in the formula: k is a radical of1m，k1hRespectively, a general driver weighting function W1mAnd a skilled driver weighting function W1hRespectively take k as the scaling factor of1m＝0.5，k1h＝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.
The personalized stability controller in the step 31) specifically includes:
311) the disturbance input of the controller is respectively the ideal yaw rate
Steering wheel angle thetaswGround disturbance moment drAnd side wind interference Fyw，Wd(s)＝[Wd1(s) Wd2(s) Wd3(s)]Is a matrix of interference input weighting functions, Wd1(s)，Wd2(s) and Wd3(s) are respectively steering wheel angle thetaswGround disturbance moment drAnd side wind interference FywTo yaw angular velocity omegarA weighting function of (a); gd(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 thetaswGround disturbance moment drAnd side wind interference FywTo yaw angular velocity omegarThe 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 W1h，W1m，W1lThree sub-weighting functions, W1h，W1m，W1lRepresenting the weighting functions of three types of drivers, namely a skilled driver, a general driver and a novice driver.
While the invention has been described in terms of its preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.
Claims (9)
1. An active front 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.
2. The active front wheel steering system according to claim 1, wherein the displacement of the ball screw driven by the nut of the ball screw and the displacement of the ball screw driven by the rotation of the large gear are superimposed on the tie rod, thereby driving the steering trapezoid and the wheel to perform a steering action.
3. The driver characteristics based active front wheel steering system as claimed in claim 1, wherein the double row planetary gear mechanism comprises: an upper row of planetary gear trains, a lower row of planetary gear trains and a planet carrier; the double-row planetary gear mechanism is connected with an upper steering column and a lower steering column, and the upper-row planetary gear train and the lower-row planetary gear train are both arranged on the planet carrier; the upper row planetary gear train comprises: an upper row of sun gears, an upper row of planet gears and an upper row of gear rings; the upper row of sun gears is fixedly connected with the upper steering column, the upper row of gear rings is fixedly arranged on the frame, and the upper row of planet gears are arranged between the upper row of sun gears and the upper row of gear rings; the lower-row planetary gear train comprises: a lower-row sun wheel, a lower-row planet wheel and a lower-row gear ring; the lower-row sun gear is fixedly connected with the lower steering column, the lower-row gear ring is connected to a worm of a worm gear, and the lower-row planet gear is arranged between the lower-row sun gear and the lower-row gear ring; the rotary motion transmitted by the worm is converted into the rotary motion of the lower steering pipe column through the lower row of gear rings, the lower row of planet wheels, the planet carrier and the lower row of sun wheels.
4. The active front steering system based on driver characteristics according to claim 1, characterized in that the master controller comprises: the system comprises an information processing unit, a driver type identification unit, an individualized control unit and a motor driving unit; the signal processing unit is electrically connected with the sensors to acquire signals acquired by the sensors in real time, and is electrically connected with other state units of the vehicle to acquire 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 personalized control unit receives the input signal of the driver type identification unit to obtain the type of the current driver, an instruction is output to the motor drive unit through the vehicle-mounted communication line, the motor drive unit respectively outputs a corner motor control signal and a power-assisted motor control signal, and the control process of the steering action is completed.
5. A control method of an active front steering system based on driver characteristics, based on any one of the systems of claims 1-4, characterized by comprising the steps of:
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, 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 steering control is completed.
6. The control method of an active front steering system based on driver characteristics according to claim 5, characterized in that the identification of the driver type in step 2) comprises in particular the steps of:
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 isdFor ideal lateral displacement, Y is the actual lateral displacement, θswTo the steering wheel angle, kp1，kp2，kp3Are all proportionality coefficients, kp1+kp2+kp31 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 kp1，kp2，kp3To obtain an ideal driver type classification method; respectively take kp1＝0.35，kp2＝0.35，kp3＝0.3；
24) Obtaining ideal lateral displacement Y according to the current operation signal of the driverdActual lateral displacement Y and steering wheel angle thetaswCalculating 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.
7. The control method of an active front wheel steering system based on driver characteristics according to claim 5, characterized in that the ideal yaw rate in step 3) is calculated by the following formula:
in the formula: omegar *Is an ideal yaw rate, idIs 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, GswFor steady state yaw rate gain, take Gsw＝0.275s-1。
8. The control method of the active front steering system based on the driver characteristics according to claim 5, 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 gains1h、W1m、W1lWeighted function W1h、W1m、W1lRespectively representing three types of driving of proficiency type, general type and novice typeA weighting function of the members;
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 W1lThe gain of (A) satisfies the driving requirements of a novice driver, the weighting function W1mAnd W1hIs given as a weighting function W1lThe 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 W1h、W1m、W1lThe selection of (a) is represented as:
in the formula: k is a radical of1m，k1hRespectively, a general driver weighting function W1mAnd a skilled driver weighting function W1hRespectively take k as the scaling factor of1m＝0.5，k1h＝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.
9. The method for controlling an active front steering system based on driver characteristics according to claim 8, wherein 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 thetaswGround disturbance moment drAnd side wind interference Fyw，Wd(s)＝[Wd1(s)Wd2(s)Wd3(s)]Is a matrix of interference input weighting functions, Wd1(s)，Wd2(s) and Wd3(s) are respectively steering wheel angle thetaswGround disturbance moment drAnd side wind interference FywTo yaw angular velocity omegarA weighting function of (a); gd(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 thetaswGround disturbance moment drAnd side wind interference FywTo yaw angular velocity omegarThe 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 W1h，W1m，W1lThree sub-weighting functions, W1h，W1m，W1lRepresenting the weighting functions of three types of drivers, namely a skilled driver, a general driver and a novice driver.
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