CN114524019A

CN114524019A - Double-winding double-motor steer-by-wire system of commercial vehicle and control method thereof

Info

Publication number: CN114524019A
Application number: CN202210264655.4A
Authority: CN
Inventors: 徐坤豪; 赵万忠; 严伟杰; 黄恒; 陈宇帆; 张文彬
Original assignee: Nanjing University of Aeronautics and Astronautics
Current assignee: Nanjing University of Aeronautics and Astronautics
Priority date: 2022-03-17
Filing date: 2022-03-17
Publication date: 2022-05-24

Abstract

The invention discloses a double-winding double-motor steer-by-wire system of a commercial vehicle and a control method thereof, wherein the double-winding double-motor steer-by-wire system comprises the following steps: the device comprises a steering wheel module, a double-winding double-motor power assisting module, a circulating ball hydraulic power assisting module, a mechanical transmission module and a steering control unit; the invention has the dual hardware redundancy functions of the motor and the winding, avoids the failure of the execution of the steering instruction caused by the fault of any single steering motor or single winding, further improves the reliability of the steer-by-wire system and enhances the safety of the vehicle; in addition, the double-winding motor has the advantages of being fused, the double-winding motor can output larger torque compared with a single-winding motor, the torque requirement required by the existing commercial vehicle steer-by-wire system is guaranteed, and the problems of high energy consumption and low response speed are solved.

Description

Double-winding double-motor steer-by-wire system of commercial vehicle and control method thereof

Technical Field

The invention belongs to the technical field of automobile steering systems, and particularly relates to a double-winding double-motor steer-by-wire system of a commercial vehicle and a control method thereof.

Background

With the increasing degree of automobile intelligence, each execution module on the automobile tends to be in wire control. The steer-by-wire system can improve the safety performance of the automobile, improve the driving characteristics and enhance the maneuverability, and becomes a hot spot of current research of people.

At present, most of the existing steer-by-wire systems are developed based on electric power steering, and due to the limitation of installation space and vehicle-mounted power supply power, the power of a motor is smaller, and the provided steering power-assisted torque is smaller, so that most of the existing steer-by-wire systems are applied to passenger vehicles with lighter weight; the steering-by-wire system of the commercial vehicle, which has heavier mass and needs larger steering power-assisted moment, is not applied in a mature way; the performance of the steering system is directly related to the driving safety of the vehicle, once an actuating motor of the steering system fails, the vehicle loses the steering capacity, so that serious consequences are caused, and the performance of the commercial vehicle is particularly the same;

in order to solve the problems, the Chinese patent application No. CN201811112412.9 discloses a double-power-assisted steering system which integrates an electro-hydraulic power-assisted moment and a linear control motor power-assisted moment, so that a larger steering moment can be provided, and the operation stability of the steering system under a high-speed working condition is ensured; however, in the above-mentioned double-power-assisted steering system, the wire control motor has only one set of windings, and when the wire control motor fails, the comprehensive performance of the steering system is greatly reduced, and the problem of low reliability still exists. The Chinese invention patent application No. CN202010004686.7 discloses a dual-motor intelligent steer-by-wire system and a synchronous control method, which realizes the redundancy of the steer-by-wire system from the hardware; however, for the steer-by-wire system of the commercial vehicle, under some special conditions, a single motor cannot provide the required steering torque when working, which is not favorable for the portability of low-speed driving, and the research on the stability control of the commercial vehicle is less.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a double-winding double-motor steer-by-wire system of a commercial vehicle and a control method thereof, so as to realize the application of steer-by-wire to large vehicles such as the commercial vehicle and the like, and solve the problems of high energy consumption and low response speed of the existing hydraulic steering system adopted by the commercial vehicle; and the commercial vehicle can be switched into different working modes under different working conditions, and the stability control ensures the safety during steering.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the invention relates to a dual-winding dual-motor steer-by-wire system of a commercial vehicle, which comprises: the device comprises a steering wheel module, a double-winding double-motor power-assisted module, a circulating ball hydraulic power-assisted module, a mechanical transmission module and a steering control unit; wherein, the first and the second end of the pipe are connected with each other,

the steering wheel module includes: the steering wheel, the first steering column, the steering wheel corner sensor, the steering wheel torque sensor, the electromagnetic clutch, the road sensing motor and the first speed reducing mechanism;

one end of the first steering column is connected with the steering wheel, and the other end of the first steering column is connected with the electromagnetic clutch; the output end of the road sensing motor is connected with the first steering column through a first speed reducing mechanism; the first speed reducing mechanism is fixed on the first steering column, and the feedback torque output by the road sensing motor is transmitted to the steering wheel through the speed reducing mechanism and the first steering column in sequence; the steering wheel corner sensor and the steering wheel torque sensor are fixedly connected with the first steering column, respectively collect corner and torque signals of the steering wheel and send the collected signals to the steering control unit;

the duplex winding bi-motor helping hand module includes: the system comprises a first double-winding motor, a second double-winding motor, a first relay control unit, a second relay control unit, a first current sensor, a second current sensor, a third current sensor, a fourth current sensor and a second speed reducing mechanism;

the first relay control unit includes: a first relay controller and a first relay; the input end of the first relay controller is connected with a power-assisted motor driving unit in the steering control unit, and the output end of the first relay controller is connected with a first relay; the second relay control unit includes: a second relay controller and a second relay; the input end of the second relay controller is connected with a power-assisted motor driving unit in the steering control unit, and the output end of the second relay controller is connected with a second relay;

the first double-winding motor includes: the motor comprises a first stator iron core, a first rotor assembly, a first base, a first set of windings, a second set of windings and a first double-winding motor output shaft; the second double winding motor includes: the second stator core, the second rotor assembly, the second base, the third set of windings, the fourth set of windings and the second double-winding motor output shaft;

the first relay control unit judges the working states of the first set of windings and the second set of windings according to the first double-winding motor control signal so as to control the connection mode of the internal contacts of the first relay; the second relay control unit judges the working states of the third set of winding and the fourth set of winding according to the second double-winding motor control signal so as to control the connection mode of the internal contact of the second relay;

the first set of windings includes: phase winding a1, phase winding B1, phase winding C1; the second set of windings includes: phase winding a1, phase winding b1, phase winding c 1; the input end of the first set of windings is divided into three branches which are respectively connected with the input end of the phase winding A1, the input end of the phase winding B1 and the input end of the phase winding C1; the input end of the second set of winding is divided into three branches which are respectively connected with the input end of the phase winding a1, the input end of the phase winding b1 and the input end of the phase winding c 1; the third set of windings includes: phase winding a2, phase winding B2, phase winding C2; the fourth set of windings includes: phase winding a2, phase winding b2, phase winding c 2; the input end of the third set of winding is divided into three branches which are respectively connected with the input end of the phase winding A2, the input end of the phase winding B2 and the input end of the phase winding C2; the input end of the fourth set of windings is divided into three branches which are respectively connected with the input end of the phase winding a2, the input end of the phase winding b2 and the input end of the phase winding c 2;

stator slots are distributed on the first stator core and the second stator core, the same phase windings of the first set of windings and the second set of windings are embedded in different stator slots in a staggered mode by 30 degrees, the same phase windings of the third set of windings and the fourth set of windings are embedded in different stator slots in a staggered mode by 30 degrees, and the first stator core and the second stator core are fixed on the first base and the second base respectively; the input end of the first set of windings is connected with the first current sensor, and the input end of the second set of windings is connected with the second current sensor; the input end of the third set of winding is connected with the third current sensor, and the input end of the fourth set of winding is connected with the fourth current sensor:

the first rotor assembly and the second rotor assembly each include: a rotor core, a rotor winding; the rotor winding is wound on a rotor iron core, and the rotor iron core is respectively fixed on output shafts of the first double-winding motor and the second double-winding motor; the first set of windings and the second set of windings work simultaneously, the third set of windings and the fourth set of windings work simultaneously to generate a synthetic magnetic field, induction current is generated in the rotor windings, the induction current drives the rotor core to rotate under the action of the magnetic field, and the rotor core outputs torque through output shafts of the first double-winding motor and the second double-winding motor;

the second speed reducing mechanism is a worm and gear speed reducing mechanism, and the output ends of the first double-winding motor and the second double-winding motor are connected with the second steering column through the second speed reducing mechanism; the second speed reducing mechanism is fixed on a second steering column, and feedback torques output by the first double-winding motor and the second double-winding motor are transmitted to the recirculating ball steering gear through the speed reducing mechanism and the second steering column in sequence;

the circulating ball hydraulic power-assisted module comprises: the hydraulic power-assisted steering system comprises a second steering column, a circulating ball type hydraulic power-assisted steering device and a hydraulic power-assisted module;

the circulating ball type hydraulic power-assisted steering gear consists of two stages of transmission pairs: the first stage is a screw and nut transmission pair, and the second stage is a rack and sector transmission pair; the second steering column is connected with the circulating ball type hydraulic power-assisted steering gear;

the mechanical transmission module comprises: the steering system comprises a steering rocker arm, a steering drag link, a left steering wheel, a left steering knuckle arm, a left steering trapezoid arm, a steering tie rod, a right steering trapezoid arm, a right steering knuckle and a right steering wheel;

the output end of the circulating ball type hydraulic power-assisted steering gear is connected with one end of a steering rocker arm through a sector, the other end of the steering rocker arm is connected with a left steering knuckle arm through a steering drag link, and the left steering knuckle arm is connected with a left steering wheel through a left steering knuckle; the left steering knuckle arm is connected with one end of a steering tie rod through a left steering trapezoid arm; the other end of the tie rod is connected with a right trapezoid arm, the right trapezoid arm is connected with a right steering knuckle through a right knuckle arm, and the right steering knuckle drives a right wheel to steer;

the hydraulic power assisting module comprises: the hydraulic pump, the hydraulic pump power-assisted motor, the third speed reducing mechanism, the oil tank, the electromagnetic directional valve, the oil pipe, the first pressure sensor and the second pressure sensor; the hydraulic pump power-assisted motor is connected with a hydraulic pump through a third speed reducing mechanism, hydraulic oil from an oil tank is pumped into the circulating ball type hydraulic power-assisted steering gear through the electromagnetic directional valve, and pressure difference is formed in the power-assisted oil cylinder to provide power assistance for a steering system; the first pressure sensor and the second pressure sensor are arranged on an oil pipe of an oil inlet and outlet way of the recirculating ball type hydraulic power steering gear and are used for detecting hydraulic power assistance on two sides of the recirculating ball type hydraulic power steering gear and sending hydraulic power assistance signals;

the steering control unit includes: a main controller and other state units of the vehicle; the input end of the main controller is electrically connected with each sensor, and acquires a steering wheel corner signal, a steering wheel torque signal, a first current signal of a first current sensor, a second current signal of a second current sensor, a third current signal of a third current sensor, a fourth current signal of a fourth current sensor and a hydraulic power-assisted signal; the other state units of the vehicle provide a vehicle speed signal, a yaw rate signal, a mass center side deviation angle signal and a lateral acceleration signal of the current vehicle state for the main controller; the output end of the main controller is connected with a road induction motor, an electromagnetic clutch, a hydraulic pump power-assisted motor, an electromagnetic directional valve, a first relay control unit and a second relay control unit;

the main controller includes: the system comprises a signal processing unit, a decision control unit, a diagnosis unit, a fault alarm unit, a power-assisted motor driving unit, an electromagnetic directional valve driving unit, an electromagnetic clutch driving unit and a road sensing motor driving unit;

the signal processing unit is electrically connected with each sensor and other vehicle state units respectively, and acquires signals of each sensor and other vehicle state signals in real time;

the decision control unit receives an input signal of the signal processing unit through a vehicle-mounted communication line;

the road sensing motor driving unit, the electromagnetic directional valve driving unit and the electromagnetic clutch driving unit receive input signals of the decision control unit through vehicle-mounted communication lines and respectively output road sensing motor control signals, electromagnetic directional valve control signals and electromagnetic clutch control signals;

the power-assisted motor driving unit receives an input signal of the decision control unit through a vehicle-mounted communication line, and respectively outputs a first double-winding motor control signal, a second double-winding motor control signal and a hydraulic pump power-assisted motor control signal to complete the control of steering action;

and the diagnosis unit is used for diagnosing whether the road sensing motor, the hydraulic pump power-assisted motor, the first double-winding motor and the second double-winding motor have faults or not, and sending a signal to the fault alarm unit if the faults occur, wherein the fault alarm unit is used for reminding a driver of fault information.

Further, the decision control unit comprises: a switching controller and a stability controller; the switching controller switches the working mode of the double-winding double-motor power assisting module according to the input signal of the signal processing unit; and the stability controller stores stability robust control algorithms corresponding to different working modes, selects the corresponding stability robust control algorithm according to the working mode of the switching controller and outputs a stability signal.

Further, the different operating modes include: the device comprises three working modes, namely a single-motor single-winding mode, a single-motor double-winding mode and a double-motor double-winding mode.

Further, the robust stability control algorithm specifically includes:

when the vehicle is in a high-speed working condition, the transmission of a steering system is large, the required steering power is small, a single-motor single-winding mode is adopted, the speed is high, the output energy is large, the output energy needs to be limited, and an H2/H infinity control algorithm is adopted;

when the vehicle is in a medium-speed working condition, the transmission of a steering system is small, the required steering power is large, a single-motor double-winding mode is adopted, the influence of the vehicle on the traffic working condition is large, the requirement on steering control precision is high, the tire cornering stiffness nonlinear characteristic is obvious, the uncertainty of vehicle parameters needs to be optimized, and a mu control algorithm is adopted;

when the vehicle is in a low-speed working condition, the transmission of a steering system is small, the required steering power assistance is large, a double-motor double-winding mode is adopted for power assistance, and a PID control algorithm is adopted at the moment.

Further, the first double-winding motor and the second double-winding motor are motors with the same type and structure and are brushless direct current motors.

Further, the first current sensor, the second current sensor, the third current sensor and the fourth current sensor are all hall current sensors.

Further, the electromagnetic clutch includes: the armature, the driving shaft, the driven shaft, the electromagnet and the friction plate group are arranged in the shell; the driving shaft is axially fixed on the first steering column, the driven shaft is axially fixed on the second steering column, the armature is sleeved on the driving shaft and can axially move, the electromagnet is fixed on the driving shaft, the friction plate group is fixed on the driven shaft, and the electromagnet is positioned between the armature and the friction plate group; the electromagnetic clutch control signal output by the main controller controls the on-off of the coil, and further controls the combination and separation of the electromagnetic clutch.

Further, the electromagnet comprises a coil and a magnet; when the wire control steering is normal, the coil of the electromagnetic clutch is not electrified, the magnet is frequently separated from the armature, the friction plate group does not transmit torque, and the electromagnetic clutch is separated; when the steer-by-wire fails, a coil of the electromagnetic clutch is electrified, the armature is attracted to the magnet so as to tightly press the friction plate set, the friction plate set transmits torque through friction force, and the electromagnetic clutch is combined; the torque of the steering wheel is transmitted to the tie rod and the left steering wheel through the first steering column, the electromagnetic clutch, the second steering column and the circulating ball type hydraulic power steering gear, and the steering action is finished.

The invention discloses a control method of a double-winding double-motor steer-by-wire system of a commercial vehicle, which is based on the system and comprises the following steps:

1) according to the current running working condition of the vehicle, executing steering operation and inputting a steering wheel angle;

2) the signal processing unit receives a steering wheel angle signal A, a steering wheel torque signal B, a hydraulic power-assisted signal C, a first current signal D, a second current signal E, a third current signal F, a fourth current signal G, a vehicle speed signal, a yaw angular velocity signal, a lateral acceleration signal and a mass center lateral deviation angle signal in real time, obtains an ideal yaw angular velocity signal, an ideal mass center lateral deviation angle signal and a required power-assisted signal of the vehicle at the current vehicle speed through calculation, and transmits the ideal yaw angular velocity signal, the ideal mass center lateral deviation angle signal and the required power-assisted signal to the decision control unit;

3) the decision control unit receives an input signal of the information processing unit, switches the working mode of the double-winding motor power-assisted module through the switching controller according to the current vehicle speed of the vehicle and the working state of the double-winding motor power-assisted module, and simultaneously selects a corresponding working mode and a stability control algorithm through the stability controller according to the current vehicle speed so as to perform stability control and power-assisted control on the steering system; the decision control unit transmits the working mode of the current steering system to the power-assisted motor driving unit and outputs an instruction to the power-assisted motor driving unit;

4) the power-assisted motor driving unit calculates and obtains the driving current of the power-assisted motor of the hydraulic pump and the driving currents of the first double-winding motor and the second double-winding motor according to the steering power-assisted signal and the stability control signal required by the current vehicle state according to the instruction output by the decision control unit, outputs the control signal of the power-assisted motor of the hydraulic pump and the control signals of the first double-winding motor and the second double-winding motor, and drives the power-assisted motor to work; the electromagnetic clutch driving unit and the electromagnetic reversing valve driving unit output electromagnetic clutch control signals and electromagnetic reversing valve control signals according to the output instructions of the decision control unit, and control the working states of the electromagnetic clutch and the electromagnetic reversing valve;

5) the diagnosis unit diagnoses faults of the motors in the running process of the vehicle, diagnoses whether the road sensing motor, the hydraulic pump power-assisted motor, the first double-winding motor and the second double-winding motor have faults or not, sends a signal to the fault alarm unit if the faults occur, and simultaneously carries out corresponding fault-tolerant control by the decision control unit, controls the winding or the motor with the faults to stop working, and carries out stability control and power-assisted control through the normal winding or the motor.

Further, the stability control in step 3) is specifically as follows:

taking the difference value between the ideal yaw velocity and the actual yaw velocity signal calculated by the signal processing unit as the input of a stability controller, and calculating a stability control signal for steering the front wheels of the vehicle through a corresponding robust control algorithm in the current working mode; and then controlling the double-winding motor which works at present to output compensation torque, and further driving the front wheels to perform corresponding torque compensation through the circulating ball type hydraulic power-assisted steering device, so that the steering stability control of the vehicle is realized.

Further, the working condition and stability control algorithm corresponding to each working mode in the step 3) specifically includes:

31) when the vehicle is in a high-speed working condition, the transmission ratio of a control steering system is larger than 25.2, the required steering power is small, a single-motor single-winding mode is adopted, the speed is high, the output energy is large, the output energy needs to be limited, and an H2/H infinity control algorithm is adopted;

32) when the vehicle is in a medium-speed working condition, the transmission ratio of a steering system is controlled to be larger than 7.8 and smaller than 25.2, a single-motor double-winding mode is adopted, the vehicle is greatly influenced by the traffic working condition at the moment, the requirement on steering control precision is high, the tire cornering stiffness nonlinear characteristic is obvious, the uncertainty of vehicle parameters needs to be optimized, and a mu control algorithm is adopted;

33) when the vehicle is in a low-speed working condition, the transmission ratio of the steering system is controlled to be smaller than 7.8, the required steering power assistance is large at the moment, a double-motor double-winding mode is adopted for power assistance, and a PID control algorithm is adopted at the moment.

Further, the switching of the operating mode of the dual-winding motor power assisting module by the switching controller specifically includes:

34) single motor single winding mode: when the vehicle is in a high-speed working condition, the decision control unit switches the working mode of the double-winding motor power-assisted module into a single-motor single-winding mode; at the moment, the electromagnetic directional valve is in a forward load or a reverse load, the first relay contact a1 is connected with the contact c1, the contact b1 is connected with the contact d1, and the hydraulic power assisting module and the first set of windings of the first double-winding motor work simultaneously to provide power assisting for the steer-by-wire system;

35) single motor double winding mode: when the vehicle is in a medium-speed working condition, the decision control unit switches the working mode of the double-winding motor power-assisted module into a single-motor double-winding mode; when the electromagnetic directional valve is in a forward load or a reverse load, the first relay contact a1 is connected with the contacts c1 and e1, and the contact b1 is connected with the contacts d1 and f 1; the hydraulic power-assisted module and two sets of windings of the first double-winding motor work simultaneously to provide power assistance for the steer-by-wire system;

36) dual motor dual winding mode: when the vehicle is in a low-speed working condition, the decision control unit switches the working mode of the double-winding motor power-assisted module into a single-motor double-winding mode; when the electromagnetic directional valve is in a forward load or a reverse load, the first relay contact a1 is connected with the contacts c1 and e1, and the contact b1 is connected with the contacts d1 and f 1; the second relay contact a2 is connected with contacts c2 and e2, and the contact b2 is connected with contacts d2 and f 2; the hydraulic power-assisted module and two windings of the two double-winding motors work simultaneously to provide power assistance for the steer-by-wire system.

Furthermore, 20Km/h is used as a medium-low speed switching point and 60Km/h is used as a medium-high speed switching point in the switching of the working modes of the steering system, the vehicle speed is a low-speed working condition between 0 and 20Km/h, the vehicle speed is a medium-speed working condition between 20 and 60Km/h, and the vehicle speed is a high-speed working condition between 20 and 60 Km/h.

Further, the step 5) specifically includes:

if one winding of a double-winding motor fails, the decision control unit controls the other winding of the double-winding motor to work; if one of the double-winding motors fails, the decision control unit controls the other double-winding motor to work;

if the circulating ball hydraulic power-assisted module breaks down, the decision control unit controls the two double-winding motors to work simultaneously; if the road sensing motor fails, the decision control unit controls the electromagnetic clutch to be closed, and the working mode of the steering system is switched to a mechanical composite power-assisted mode.

The invention has the beneficial effects that:

the invention has the dual hardware redundancy functions of the motor and the winding, avoids the failure of the execution of the steering instruction caused by the fault of any single steering motor or single winding, further improves the reliability of the steer-by-wire system and enhances the safety of the vehicle; in addition, the advantages of the double-winding motor are combined, and compared with a single-winding motor, the double-winding motor can output larger torque, so that the torque requirement required by the existing commercial vehicle steer-by-wire system is ensured, and the problems of higher energy consumption and low response speed are solved;

according to the invention, different working modes and stability control algorithms can be selected according to the working condition of the vehicle, so that the stability of the vehicle during steering can be better ensured, and the driving safety of the vehicle is enhanced.

Drawings

FIG. 1 is a block diagram of the system of the present invention;

FIG. 2 is a schematic structural diagram of a dual-winding dual-motor of the present invention;

FIG. 3 is a flow chart of a control method of the steering system of the present invention;

FIG. 4 is a flow chart of decision unit control according to the present invention;

in the figure, 1-steering wheel, 2-steering wheel angle sensor, 3-first steering column, 4-steering wheel torque sensor, 5-first speed reducing mechanism, 6-electromagnetic clutch, 7-double winding double-motor power-assisted module, 8-second steering column, 9-screw and nut transmission pair, 10-rack and sector transmission pair, 11-circulating ball type hydraulic power-assisted steering device, 12-steering rocker arm, 17-steering drag link, 13-left steering wheel, 14-left steering knuckle, 15-left steering knuckle arm, 16-left steering trapezoid arm, 18-hydraulic power-assisted module, 19-electromagnetic reversing valve, 20-steering tie rod, 21-right steering trapezoid arm, 22-right steering knuckle arm, 23-right steering knuckle, 24-right steering wheel, 25-oil tank, 26-hydraulic pump power motor, 27-hydraulic pump, 28-vehicle other state unit, 29-main controller module, 30-road sensing motor, 52-second speed reducing mechanism, 71-first relay control unit, 72-first current sensor, 73-first set of winding, 74-second set of winding, 75-second current sensor, 76-third set of winding, 77-third current sensor, 78-second relay control unit, 79-fourth current sensor, 80-fourth set of winding, 81-first pressure sensor, 82-second pressure sensor;

the control signal comprises an A-steering wheel angle signal, a B-steering wheel torque signal, a C-hydraulic power assisting signal, a D-first current signal, an E-second current signal, an F-third current signal, a G-fourth current signal, an H-first relay control signal, an I-second relay control signal, a J-hydraulic pump power assisting motor control signal, a K-electromagnetic directional valve control signal, an L-electromagnetic clutch control signal, an M-vehicle speed signal, an N-yaw rate signal, an O-mass center lateral deviation angle signal and a P-lateral acceleration signal.

Detailed Description

In order to facilitate understanding of those skilled in the art, the present invention is further described below with reference to the following examples and the accompanying drawings, which are not intended to limit the present invention.

Referring to fig. 1 and 2, the dual-winding dual-motor steer-by-wire system of a commercial vehicle of the present invention comprises: the device comprises a steering wheel module, a double-winding double-motor power-assisted module 7, a circulating ball hydraulic power-assisted module, a mechanical transmission module and a steering control unit; wherein the content of the first and second substances,

the steering wheel module includes: the steering wheel device comprises a steering wheel 1, a first steering column 3, a steering wheel angle sensor 2, a steering wheel torque sensor 4, an electromagnetic clutch 6, a road sensing motor 30 and a first speed reducing mechanism 5;

one end of the first steering column 3 is connected with the steering wheel 1, and the other end of the first steering column is connected with the electromagnetic clutch 6; the output end of the road sensing motor 30 is connected with the first steering column 3 through a first speed reducing mechanism 5; the first speed reducing mechanism 5 is fixed on the first steering column, and the feedback torque output by the road sensing motor is transmitted to the steering wheel through the speed reducing mechanism and the first steering column in sequence; the steering wheel corner sensor 2 and the steering wheel torque sensor 4 are fixedly connected with the first steering column 3, respectively collect corner and torque signals of a steering wheel, and send the collected signals to the steering control unit;

the electromagnetic clutch includes: the armature, the driving shaft, the driven shaft, the electromagnet and the friction plate set are arranged in the shell; the driving shaft is axially fixed on the first steering column, the driven shaft is axially fixed on the second steering column, the armature is sleeved on the driving shaft and can axially move, the electromagnet is fixed on the driving shaft, the friction plate group is fixed on the driven shaft, and the electromagnet is positioned between the armature and the friction plate group; the electromagnetic clutch control signal output by the main controller controls the on-off of the coil so as to control the combination and separation of the electromagnetic clutch;

the electromagnet comprises a coil and a magnet; when the wire control steering is normal, the coil of the electromagnetic clutch is not electrified, the magnet is frequently separated from the armature, the friction plate group does not transmit torque, and the electromagnetic clutch is separated; when the steer-by-wire fails, a coil of the electromagnetic clutch is electrified, the armature is attracted to the magnet so as to tightly press the friction plate set, the friction plate set transmits torque through friction force, and the electromagnetic clutch is combined; the torque of the steering wheel is transmitted to the tie rod and the left steering wheel through the first steering column, the electromagnetic clutch, the second steering column and the circulating ball type hydraulic power steering gear, and the steering action is finished.

The dual-winding dual-motor power assisting module 7 comprises: a first double-winding motor, a second double-winding motor, a first relay control unit 71, a second relay control unit 78, a first current sensor 72, a second current sensor 75, a third current sensor 77, a fourth current sensor 79, and the second reduction gear mechanism 52;

the first relay control unit 71 includes: a first relay controller and a first relay; the input end of the first relay controller is connected with a power-assisted motor driving unit in the steering control unit, and the output end of the first relay controller is connected with a first relay; the second relay control unit includes: a second relay controller and a second relay; the input end of the second relay controller is connected with a power-assisted motor driving unit in the steering control unit, and the output end of the second relay controller is connected with a second relay;

the first double-winding motor includes: the rotor comprises a first stator core, a first rotor assembly, a first base, a first set of windings 73, a second set of windings 74 and a first double-winding motor output shaft; the second double winding motor includes: a second stator core, a second rotor assembly, a second base, a third set of windings 76, a fourth set of windings 80 and a second double-winding motor output shaft;

the first set of windings 73 includes: phase winding a1, phase winding B1, phase winding C1; the second set of windings 74 includes: phase winding a1, phase winding b1, phase winding c 1; the input end of the first set of winding 73 is divided into three branches which are respectively connected with the input end of the phase winding A1, the input end of the phase winding B1 and the input end of the phase winding C1; the input end of the second set of winding 74 is divided into three branches which are respectively connected with the input end of the phase winding a1, the input end of the phase winding b1 and the input end of the phase winding c 1; the third set of windings 76 includes: phase winding a2, phase winding B2, phase winding C2; the fourth set of windings 80 includes: phase winding a2, phase winding b2, phase winding c 2; the input end of the third set of winding 76 is divided into three branches which are respectively connected with the input end of the phase winding A2, the input end of the phase winding B2 and the input end of the phase winding C2; the input end of the fourth set of winding 80 is divided into three branches which are respectively connected with the input end of the phase winding a2, the input end of the phase winding b2 and the input end of the phase winding c 2;

stator slots are distributed on the first stator core and the second stator core, the same phase windings of the first set of winding 73 and the second set of winding 74 are embedded in different stator slots in a staggered mode by 30 degrees, the same phase windings of the third set of winding 76 and the fourth set of winding 80 are embedded in different stator slots in a staggered mode by 30 degrees, and the first stator core and the second stator core are fixed on the first base and the second base respectively; the input of the first set of windings 73 is connected to a first current sensor 72, and the input of the second set of windings 74 is connected to a second current sensor 75; the input of the third set of windings 76 is connected to a third current sensor 77, and the input of the fourth set of windings 80 is connected to a fourth current sensor 79:

the first rotor assembly and the second rotor assembly each include: a rotor core, a rotor winding; the rotor winding is wound on a rotor iron core, and the rotor iron core is respectively fixed on output shafts of the first double-winding motor and the second double-winding motor; the first set of winding 73 and the second set of winding 74 work simultaneously, the third set of winding 76 and the fourth set of winding 80 work simultaneously to generate a synthetic magnetic field, induction current is generated in the rotor winding, the induction current drives the rotor core to rotate under the action of the magnetic field, and the rotor core outputs torque through output shafts of the first double-winding motor and the second double-winding motor;

the second speed reducing mechanism 52 is a worm and gear speed reducing mechanism, and the output ends of the first double-winding motor and the second double-winding motor are connected with the second steering column through the second speed reducing mechanism; the second speed reducing mechanism is fixed on a second steering column, and feedback torques output by the first double-winding motor and the second double-winding motor are transmitted to the recirculating ball steering gear through the speed reducing mechanism and the second steering column in sequence;

the circulating ball hydraulic power-assisted module comprises: a second steering column 8, a recirculating ball hydraulic power steering 11 and a hydraulic power module 18;

the recirculating ball type hydraulic power-assisted steering gear 11 consists of two stages of transmission pairs: the first stage is a screw and nut transmission pair 9, and the second stage is a rack and sector transmission pair 10; the second steering column 8 is connected with a recirculating ball type hydraulic power-assisted steering gear 11;

the mechanical transmission module comprises: the steering system comprises a steering rocker arm 12, a steering drag link 17, a left steering wheel 13, a left steering knuckle 14, a left steering knuckle arm 15, a left steering trapezoid arm 16, a steering tie rod 20, a right steering trapezoid arm 21, a right steering knuckle arm 22, a right steering knuckle 23 and a right steering wheel 24;

the output end of the recirculating ball type hydraulic power-assisted steering gear 11 is connected with one end of a steering rocker arm 12 through a sector, the other end of the steering rocker arm 12 is connected with a left steering knuckle arm 15 through a steering drag link 17, and the left steering knuckle arm 15 is connected with a left steering wheel 13 through a left steering knuckle 14; the left knuckle arm 15 is connected to one end of a tie rod 20 via a left steering trapezoid arm 16; the other end of the tie rod 20 is connected with a right trapezoid arm 21, the right trapezoid arm 21 is connected with a right knuckle 23 through a right knuckle arm 22, and the right knuckle 23 drives a right wheel 24 to steer;

the hydraulic assist module 18 includes: the hydraulic pump 27, the hydraulic pump power-assisted motor 26, the third speed reducing mechanism, the oil tank 25, the electromagnetic directional valve 19, the oil pipe, the first pressure sensor 81 and the second pressure sensor 82; the hydraulic pump power-assisted motor 26 is connected with a hydraulic pump 27 through a third speed reducing mechanism, hydraulic oil from an oil tank is pumped into the circulating ball type hydraulic power-assisted steering device 11 through the electromagnetic directional valve 19, and pressure difference is formed in a power-assisted oil cylinder to provide power assistance for a steering system; the first pressure sensor 81 and the second pressure sensor 82 are installed on oil pipes of an oil inlet and outlet way of the recirculating ball type hydraulic power steering gear 11, and are used for detecting hydraulic power assistance on two sides of the recirculating ball type hydraulic power steering gear and sending hydraulic power assistance signals;

the steering control unit includes: a main controller and other state units of the vehicle; the input end of the main controller is electrically connected with each sensor, and acquires a steering wheel angle signal, a steering wheel torque signal, a first current signal of a first current sensor 72, a second current signal of a second current sensor 75, a third current signal of a third current sensor 77, a fourth current signal of a fourth current sensor 79 and a hydraulic power assisting signal; the other state units of the vehicle provide a vehicle speed signal, a yaw rate signal, a mass center side deviation angle signal and a lateral acceleration signal of the current vehicle state for the main controller; the output end of the main controller is connected with a road induction motor, an electromagnetic clutch, a hydraulic pump power-assisted motor, an electromagnetic directional valve, a first relay control unit and a second relay control unit;

and the diagnosis unit is used for diagnosing whether the road sensing motor, the hydraulic pump power-assisted motor, the first duplex-winding motor and the second duplex-winding motor have faults or not, and if the faults occur, sending a signal to the fault alarm unit, and the fault alarm unit is used for reminding a driver of fault information.

Wherein the decision control unit comprises: a switching controller and a stability controller; the switching controller switches the working mode of the double-winding double-motor power assisting module according to the input signal of the signal processing unit; the stability robust control algorithms corresponding to different working modes are stored in the stability controller, the corresponding stability robust control algorithms are selected according to the working modes of the switching controller, and stability signals are output.

The different operating modes include: the device comprises three working modes, namely a single-motor single-winding mode, a single-motor double-winding mode and a double-motor double-winding mode.

Specifically, the robust stability control algorithm specifically includes:

In an example, the first double-winding motor and the second double-winding motor are motors of the same type and structure, and are brushless direct current motors.

In an example, the first current sensor, the second current sensor, the third current sensor, and the fourth current sensor are all hall current sensors.

Referring to fig. 3, the control method of the commercial vehicle dual-winding dual-motor steer-by-wire system according to the present invention includes the following steps based on the system:

5) the diagnosis unit diagnoses faults of the motors in the running process of the vehicle, diagnoses whether the road induction motor, the hydraulic pump power-assisted motor, the first double-winding motor and the second double-winding motor have faults or not, sends a signal to the fault alarm unit if the faults occur, and simultaneously performs corresponding fault-tolerant control by the decision control unit, controls the faulty winding or motor to stop working, and performs stability control and power-assisted control through the normal winding or motor.

Wherein, the stability control in the step 3) is specifically as follows:

Referring to fig. 4, the different operating modes include: the device comprises three working modes, namely a single-motor single-winding mode, a single-motor double-winding mode and a double-motor double-winding mode.

Specifically, the working condition and stability control algorithm corresponding to each working mode in the step 3) specifically includes:

The switching of the double-winding motor power-assisted module by the switching controller specifically comprises the following steps:

In an example, 20Km/h is used as a medium-low speed switching point and 60Km/h is used as a medium-high speed switching point in the switching of the working modes of the steering system, the vehicle speed is a low-speed working condition between 0 and 20Km/h, the vehicle speed is a medium-speed working condition between 20 and 60Km/h, and the vehicle speed is a high-speed working condition between 20 and 60 Km/h.

Specifically, the step 5) specifically includes:

if the circulating ball hydraulic power-assisted module breaks down, the decision control unit controls the two double-winding motors to work simultaneously; if the road sensing motor is in fault, the decision control unit controls the electromagnetic clutch to be closed, and the working mode of the steering system is switched to a mechanical composite power-assisted mode.

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

1. The utility model provides a two motor drive-by-wire steering systems of duplex winding of commercial car which characterized in that includes: the system comprises a steering wheel module, a double-winding double-motor power-assisted module, a circulating ball hydraulic power-assisted module, a mechanical transmission module and a steering control unit;

the steering control unit includes: a main controller and other state units of the vehicle; the input end of the main controller is electrically connected with each sensor, and acquires a steering wheel angle signal, a steering wheel torque signal, a first current signal of a first current sensor, a second current signal of a second current sensor, a third current signal of a third current sensor, a fourth current signal of a fourth current sensor and a hydraulic power-assisted signal; the other state units of the vehicle provide a vehicle speed signal, a yaw rate signal, a mass center side deviation angle signal and a lateral acceleration signal of the current vehicle state for the main controller; the output end of the main controller is connected with a road induction motor, an electromagnetic clutch, a hydraulic pump power-assisted motor, an electromagnetic directional valve, a first relay control unit and a second relay control unit;

2. The dual-winding dual-motor steer-by-wire system of a commercial vehicle of claim 1, wherein the decision control unit comprises: a switching controller and a stability controller; the switching controller switches the working mode of the double-winding double-motor power assisting module according to the input signal of the signal processing unit; and the stability controller stores stability robust control algorithms corresponding to different working modes, selects the corresponding stability robust control algorithm according to the working mode of the switching controller and outputs a stability signal.

3. The dual-winding dual-motor steer-by-wire system of a commercial vehicle of claim 1, wherein said different operating modes comprise: the device comprises three working modes, namely a single-motor single-winding mode, a single-motor double-winding mode and a double-motor double-winding mode.

4. The commercial vehicle dual-winding dual-motor steer-by-wire system according to claim 1, wherein the robust stability control algorithm is specifically:

when the vehicle is in a low-speed working condition, the transmission of a steering system is small, the required steering power assistance is large, a double-motor double-winding mode is adopted for power assistance, and a PID control algorithm is adopted.

5. The dual-winding dual-motor steer-by-wire system of a commercial vehicle of claim 1, wherein said electromagnetic clutch comprises: the armature, the driving shaft, the driven shaft, the electromagnet and the friction plate group are arranged in the shell; the driving shaft is axially fixed on the first steering column, the driven shaft is axially fixed on the second steering column, the armature is sleeved on the driving shaft and can axially move, the electromagnet is fixed on the driving shaft, the friction plate group is fixed on the driven shaft, and the electromagnet is positioned between the armature and the friction plate group; the electromagnetic clutch control signal output by the main controller controls the on-off of the coil, and further controls the combination and separation of the electromagnetic clutch.

6. A control method of a double-winding double-motor steer-by-wire system of a commercial vehicle is based on the system of any one of claims 1 to 5, and is characterized by comprising the following steps:

4) the power assisting motor driving unit is used for calculating to obtain the driving current of the power assisting motor of the hydraulic pump and the driving currents of the first double-winding motor and the second double-winding motor according to a steering power assisting signal and a stability control signal required by the current vehicle state according to an instruction output by the decision control unit, outputting the control signal of the power assisting motor of the hydraulic pump and the control signals of the first double-winding motor and the second double-winding motor and driving the power assisting motor and the second double-winding motor to work; the electromagnetic clutch driving unit and the electromagnetic reversing valve driving unit output electromagnetic clutch control signals and electromagnetic reversing valve control signals according to the output instructions of the decision control unit, and control the working states of the electromagnetic clutch and the electromagnetic reversing valve;

7. The control method of the commercial vehicle dual-winding dual-motor steer-by-wire system according to claim 6, wherein the stability control in step 3) is as follows:

8. The control method of the commercial vehicle dual-winding dual-motor steer-by-wire system according to claim 6, wherein the working condition and stability control algorithm corresponding to each working mode in the step 3) specifically comprises:

33) when the vehicle is in a low-speed working condition, the transmission ratio of the steering system is controlled to be smaller than 7.8, the required steering power assistance is large, a double-motor double-winding mode is adopted for power assistance, and a PID control algorithm is adopted.

9. The control method of the commercial vehicle dual-winding dual-motor steer-by-wire system according to claim 6, wherein the switching of the operating mode of the dual-winding motor power-assisted module by the switching controller specifically comprises: