Drive-by-wire independent steering system and control method thereof

Abstract

The invention discloses a drive-by-wire independent steering system and a control method thereof, and the system comprises a detection mechanism which is used for detecting a steering wheel angle signal, a current / torque signal of a steering motor, a vehicle speed signal and a front wheel angle signal; the executing mechanism comprises a two-way electromagnetic valve mechanism, two sets of steering motors and two sets of steering mechanisms, and the two sets of steering motors and the two sets of steering mechanisms are symmetrically arranged relative to the two-way electromagnetic valve mechanism; the steering motors are connected with the front wheels through the wheel steering mechanisms, and the steering mechanisms are connected through the two-way electromagnetic valve mechanism. And the control unit is respectively connected with the detection mechanism, the steering motor and the bidirectional electromagnetic valve mechanism. The system is simple in structure, has redundancy, is easy to control, is quick in response, can achieve independent steering of left and right wheels under the normal condition of a steer-by-wire vehicle, improves the steering performance of the vehicle, and improves the maneuverability of the whole vehicle; when the steering motor breaks down, the gears and the racks on the two sides can be combined into a whole in the shortest time, and safe driving and steering of the automobile are guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle steering systems, and in particular relates to a wire-controlled independent steering system and a control method thereof. Background Art

[0002] With the continuous development of automobile technology, automobile steering systems have gone through four stages: mechanical steering, hydraulic power steering, electro-hydraulic steering and electric power steering. With the in-depth development of automotive electronic technology, a new type of steering system demand has received widespread attention, namely wire-controlled steering.

[0003] The steer-by-wire system eliminates the mechanical connection between the steering wheel and the steering wheel, and completely realizes steering by electric energy, getting rid of the various limitations of traditional steering systems.

[0004] There is no need to be limited by the traditional steering actuator. The combined steering actuator can control the left and right front wheel steering separately through the dual motor structure, which can not only freely design the force transmission characteristics of the car steering, but also design the angle transmission characteristics of the car steering, bringing unlimited space for the design of the car steering characteristics and improving the vehicle steering performance; at the same time, the existing dual motor redundant device can be adopted to improve the steering reliability and safety; the structure is simple, easy to control, and fast response.

[0005] The prior art CN109850010B discloses a wire-controlled independent steering system and method thereof, which can realize flexible coordinated control of independent steering of left and right wheels during normal wire-controlled steering, increase the handling stability of the vehicle, and ensure that the vehicle can normally drive in a straight line and turn when the steering system fails; however, it has technical problems such as complex mechanical structure and control strategy, slow response and high cost. Summary of the invention

[0006] The purpose of the present invention is to provide a wire-controlled independent steering system and a control method thereof, which can not only realize independent steering of the left and right wheels under normal circumstances of a wire-controlled steering vehicle, thereby improving the vehicle's steering performance and the vehicle's maneuverability; but also can combine the gears and racks on both sides into one in the shortest time when a steering motor fails, thereby ensuring safe driving and steering of the vehicle.

[0007] In order to solve the above technical problems, the technical solution of the present invention is: a wire-controlled independent steering system, comprising:

[0008] A detection mechanism, the detection mechanism is used to detect a steering wheel angle signal, a current / torque signal of a steering motor, a rack travel sensor, a vehicle speed signal and a front wheel angle signal;

[0009] An actuator, the actuator comprising a two-way solenoid valve mechanism and two sets of steering motors and steering mechanisms symmetrically arranged about the two-way solenoid valve mechanism; the steering mechanism is connected to the front wheel through a steering tie rod, a steering knuckle arm and a steering knuckle, and the two sets of steering mechanisms are connected through a two-way solenoid valve mechanism;

[0010] and a control unit, wherein the control unit is respectively connected with the detection mechanism, the steering motor, and the bidirectional solenoid valve mechanism.

[0011] The steering mechanism is a rack and pinion steering gear, comprising a gear and a rack;

[0012] The steering motor is connected to the gear through a speed reduction mechanism, and the gear is connected to the rack;

[0013] The inner side of the rack is connected to the two-way solenoid valve mechanism through a shaft, and the outer side of the rack is connected to the front wheel through a steering tie rod, a steering knuckle arm and a steering knuckle;

[0014] The bidirectional solenoid valve mechanism includes a bidirectional solenoid valve and a hydraulic cylinder; the bidirectional solenoid valve includes a solenoid coil, a valve body and a valve core, and the valve is opened and closed by current control; the hydraulic cylinder includes an inner cavity and an outer cavity, a through hole is opened below the inner cavity, the outer cavity shell is connected to the steering mechanism on one side through a shaft, and the inner cavity is connected to the steering mechanism on the other side through a piston rod.

[0015] The detection mechanism includes a steering wheel angle sensor, a vehicle speed sensor, a front wheel angle sensor, a motor current / torque sensor and a rack travel sensor;

[0016] The steering wheel angle sensor is used to detect the steering wheel angle signal of the vehicle;

[0017] The vehicle speed sensor is used to detect the vehicle speed;

[0018] The wheel angle sensor is used to detect the angles of the left and right wheels;

[0019] The motor current / torque sensor is used to detect the current and torque of the steering motor;

[0020] The rack travel sensor is used to detect the position of the rack.

[0021] A vehicle is also provided, comprising the independent steering-by-wire system as described in any one of the above items.

[0022] A control method for a wire-controlled independent steering system is also provided, comprising:

[0023] Detect the steering wheel angle signal, the current / torque signal of the steering motor, the vehicle speed signal and the front wheel angle signal, and transmit them to the control unit;

[0024] The steering transmission ratio of the steering motor is determined according to the steering wheel angle signal, the vehicle speed signal and the front wheel angle signal, and the two-way solenoid valve is controlled to be in an energized state. The inside of the hydraulic cylinder is connected to the outside, and the control unit controls the steering motor to drive the left and right wheels to achieve independent steering.

[0025] The steering motor is detected to see if it is faulty based on its current / torque signal. When the steering motor on one side fails, the two-way solenoid valve is controlled to be in a power-off state, the two-way solenoid valve is closed, and the hydraulic cylinder is in a closed state, thereby combining with the racks on both sides to control the steering motor on the side without fault to drive the racks on both sides to drive the wheels to achieve normal driving and steering.

[0026] The following steps are also included:

[0027] When the steering motor on one side fails, the steering angles of the wheels on both sides are not equal and the angle difference is greater than the preset steering angle threshold x, that is, |θleft-θright|>x, the two-way solenoid valve is closed; wherein θleft and θright represent the steering angles of the left wheel and the right wheel respectively, and the positions of the racks on both sides are also different at this time;

[0028] When the vehicle speed is less than or equal to the preset vehicle speed y and the steering wheel angle is less than the preset angle, the control unit sends a command to energize the two-way solenoid valve to open the valve, and the control unit drives the rack on the side without fault to drive the wheel to achieve the required rotation direction and angle after calculation;

[0029] When |θleft-θright|<x, the control unit sends a command to close the two-way solenoid valve, combining the gears and racks on both sides into one, and the steering motor on the fault-free side drives the racks on both sides to drive the wheels to achieve normal driving and steering. At the same time, closed-loop verification is performed by detecting the rack travel sensor signal.

[0030] The preset angle threshold x ranges from 8° to 15°.

[0031] The preset vehicle speed y ranges from 15km / h to 25km / h.

[0032] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any of the above methods when executing the computer program.

[0033] A computer-readable storage medium stores a computer program, wherein the computer program, when executed by a processor, implements the steps of any of the methods described above.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The device of the present invention has a simple structure, redundancy, easy control and rapid response.

[0036] 2. In the present invention, when the vehicle is running normally, the left and right steering motors are used to drive the left and right racks respectively to perform independent steering coordination control; when one of the left and right steering motors fails, at high speed, the two-way solenoid valve is closed by powering off to allow the left and right racks to immediately combine into one, and another motor is used to drive the rack and pinion to ensure normal steering of the vehicle; the present invention can achieve flexible coordinated control of the independent steering of the left and right wheels during normal wire-controlled steering, enhance the vehicle's steering performance, and improve the vehicle's maneuverability, and can also ensure that the vehicle can run normally when the steering system fails.

[0037] 3. When the steering motor of the present invention fails, the gears and racks on both sides can be combined into one in the shortest time to ensure safe steering of the vehicle.

[0038] 4. After a fault occurs, the present invention can cut off the power to the two-way solenoid valve to combine the gear rack steering mechanisms on both sides into one, drive the rack on the side without the fault to drive the wheels to achieve the required rotation direction and angle, and ensure that the vehicle can drive close to a straight line and turn as a whole.

[0039] 5. The present invention can realize a variable transmission ratio and improve steering performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a structural schematic diagram of an embodiment of the present invention;

[0041] Figure 2 It is a schematic diagram of a flow chart of an embodiment of the present invention;

[0042] Figure 3 This is a schematic diagram of the control structure of the electronic control unit in an embodiment of the present invention;

[0043] Figure 4 Schematic diagram of the system fault-tolerant control structure when the left steering motor fails in an embodiment of the present invention;

[0044] In the figure, 1-control unit, 2-left steering motor controller, 3-left steering motor, 4-bidirectional solenoid valve, 5-right steering motor controller, 6-right steering motor, 7-left rack and pinion mechanism, 8-left rack travel sensor, 9-actuator, 10-right rack travel sensor, 11-right rack and pinion mechanism. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0046] refer to Figure 1-Figure 4 , the technical solution of the present invention is:

[0047] Embodiment 1:

[0048] A wire-controlled independent steering system comprises a detection mechanism, an actuator 9 and a control unit 1.

[0049] The detection mechanism is used to detect the steering wheel angle signal, the current / torque signal of the steering motor, the rack travel sensor, the vehicle speed signal and the front wheel angle signal. The actuator 9 includes a two-way solenoid valve 4 mechanism and two groups of steering motors and steering mechanisms symmetrically arranged about the two-way solenoid valve 4 mechanism; the steering mechanism is connected to the front wheel through a steering tie rod, a steering knuckle arm and a steering knuckle, and the two groups of steering mechanisms are connected through a two-way solenoid valve 4 mechanism. The control unit 1 is respectively connected to the detection mechanism, the steering motor, and the two-way solenoid valve 4 mechanism.

[0050] The steering mechanism is a rack and pinion steering gear, including a gear and a rack; the steering mechanism includes: a left steering motor controller 2, a left steering motor 3, a right steering motor controller 5 and a right steering motor 6. When the vehicle is running normally, the left and right steering motors are used to drive the left and right racks respectively to perform independent steering coordination control; when one of the left and right steering motors fails, at high speed, the left and right racks are immediately combined into one by shutting down the two-way solenoid valve by power failure, and the other motor is used to drive the rack and pinion to ensure normal steering of the vehicle; the present invention can not only realize flexible coordinated control of the independent steering of the left and right wheels during normal wire-controlled steering, improve the steering performance of the vehicle, and improve the maneuverability of the whole vehicle, but also ensure that the vehicle can run normally when the steering system fails.

[0051] The steering motor is connected to the gear through a reduction mechanism, and the gear is connected to the rack to form a left rack-and-pinion mechanism 7 and a right rack-and-pinion mechanism 11 .

[0052] The inner side of the rack is connected to the two-way solenoid valve 4 mechanism through a shaft, and the outer side of the rack is connected to the front wheel through a steering tie rod, a steering knuckle arm and a steering knuckle.

[0053] The two-way solenoid valve 4 mechanism includes a two-way solenoid valve 4 and a hydraulic cylinder; the two-way solenoid valve 4 includes an electromagnetic coil, a valve body and a valve core, which is controlled by current to open and close the valve; the hydraulic cylinder includes an inner cavity and an outer cavity, a through hole is opened below the inner cavity, the outer cavity shell is connected to the steering mechanism on one side through an axis, and the inner cavity is connected to the steering mechanism on the other side through a piston rod. By cutting off the power to the two-way solenoid valve, the gear rack steering mechanisms on both sides are combined into one, and the rack on the fault-free side is driven to drive the wheels to achieve the required rotation direction and angle, ensuring that the vehicle can drive close to a straight line and turn as a whole.

[0054] Further, the detection mechanism includes a steering wheel angle sensor, a vehicle speed sensor, a front wheel angle sensor, a motor current / torque sensor and a rack travel sensor; the rack travel sensor includes a left rack travel sensor 8 and a right rack travel sensor 10. The steering wheel angle sensor is used to detect the steering wheel angle signal of the vehicle. The vehicle speed sensor is used to detect the vehicle speed. The wheel angle sensor is used to detect the angles of the left and right wheels. The motor current / torque sensor is used to detect the current and torque of the steering motor. The rack travel sensor is used to detect the position of the rack.

[0055] Embodiment 2:

[0056] The present invention also provides a vehicle, comprising the independent steering-by-wire system as described in any one of the above items.

[0057] Embodiment 3:

[0058] The present invention also provides a control method for a wire-controlled independent steering system, comprising:

[0059] S1, detecting the steering wheel angle signal, the current / torque signal of the steering motor, the vehicle speed signal and the front wheel angle signal, and transmitting them to the control unit 1;

[0060] S2, determining the steering transmission ratio of the steering motor according to the steering wheel angle signal, the vehicle speed signal and the front wheel angle signal, controlling the two-way solenoid valve 4 to be in an energized state, the inside of the hydraulic cylinder is connected to the outside, and controlling the steering motor through the control unit 1 to drive the left and right wheels to achieve independent steering;

[0061] S3. Detect whether the steering motor is faulty based on the current / torque signal of the steering motor. When the steering motor on one side fails, control the two-way solenoid valve 4 to be in a power-off state, close the two-way solenoid valve 4, and form a closed state of the hydraulic cylinder, thereby combining with the racks on both sides as a whole, and control the steering motor on the side without fault to drive the racks on both sides to drive the wheels to achieve normal driving and steering.

[0062] The control method further comprises the following steps:

[0063] When the steering motor on one side fails, the steering angles of the wheels on both sides are not equal and the angle difference is greater than the preset steering angle threshold x, that is, |θleft-θright|>x, the two-way solenoid valve 4 is closed; wherein θleft and θright represent the steering angles of the left wheel and the right wheel respectively, and at this time, the positions of the racks on both sides are also different;

[0064] When the vehicle speed is less than or equal to the preset vehicle speed y and the steering wheel angle is less than the preset angle, the control unit 1 sends a command to energize the two-way solenoid valve 4 to open the valve, and the control unit 1 drives the rack on the side without fault to drive the wheel to achieve the required rotation direction and angle after calculation;

[0065] When |θleft-θright|<x, the control unit 1 sends a command to close the two-way solenoid valve 4, combining the gears and racks on both sides into one, and the steering motor on the fault-free side drives the racks on both sides to drive the wheels to achieve normal driving and steering, and at the same time, closed-loop verification is performed by detecting the rack travel sensor signal.

[0066] The preset angle threshold x has a value range of 8°-15°, and in this embodiment, it is 10°.

[0067] The preset vehicle speed y has a value range of 15km / h to 25km / h, and in this embodiment, it is 20km / h.

[0068] Embodiment 4:

[0069] The present invention also provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any of the above methods when executing the computer program.

[0070] Embodiment 5:

[0071] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of any of the above methods when executed by a processor.

[0072] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0073] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0074] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0075] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0076] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A wire-controlled independent steering system, characterized in that: include: A detection mechanism, the detection mechanism is used to detect a steering wheel angle signal, a current / torque signal of a steering motor, a rack travel sensor, a vehicle speed signal and a front wheel angle signal; An actuator, the actuator comprising a two-way solenoid valve mechanism and two sets of steering motors and steering mechanisms symmetrically arranged about the two-way solenoid valve mechanism; the steering mechanism is connected to the front wheel through a steering tie rod, a steering knuckle arm and a steering knuckle, and the two sets of steering mechanisms are connected through a two-way solenoid valve mechanism; and a control unit, wherein the control unit is respectively connected with the detection mechanism, the steering motor, and the bidirectional solenoid valve mechanism.

2. The independent steering-by-wire system according to claim 1, characterized in that: The steering mechanism is a rack and pinion steering gear, comprising a gear and a rack; The steering motor is connected to the gear through a speed reduction mechanism, and the gear is connected to the rack; The inner side of the rack is connected to the two-way solenoid valve mechanism through a shaft, and the outer side of the rack is connected to the front wheel through a steering tie rod, a steering knuckle arm and a steering knuckle; The bidirectional solenoid valve mechanism includes a bidirectional solenoid valve and a hydraulic cylinder; the bidirectional solenoid valve includes a solenoid coil, a valve body and a valve core, and the valve is opened and closed by current control; the hydraulic cylinder includes an inner cavity and an outer cavity, a through hole is opened below the inner cavity, the outer cavity shell is connected to the steering mechanism on one side through a shaft, and the inner cavity is connected to the steering mechanism on the other side through a piston rod.

3. The independent steer-by-wire system according to claim 1, characterized in that: The detection mechanism includes a steering wheel angle sensor, a vehicle speed sensor, a front wheel angle sensor, a motor current / torque sensor and a rack travel sensor; The steering wheel angle sensor is used to detect the steering wheel angle signal of the vehicle; The vehicle speed sensor is used to detect the vehicle speed; The wheel angle sensor is used to detect the angles of the left and right wheels; The motor current / torque sensor is used to detect the current and torque of the steering motor; The rack travel sensor is used to detect the position of the rack.

4. A vehicle, characterized in that: It comprises the independent steering-by-wire system as claimed in any one of claims 1 to 3.

5. A control method for an independent steering-by-wire system according to any one of claims 1 to 3, characterized in that: include: Detect the steering wheel angle signal, the current / torque signal of the steering motor, the vehicle speed signal and the front wheel angle signal, and transmit them to the control unit; The steering transmission ratio of the steering motor is determined according to the steering wheel angle signal, the vehicle speed signal and the front wheel angle signal, and the two-way solenoid valve is controlled to be in an energized state. The inside of the hydraulic cylinder is connected to the outside, and the control unit controls the steering motor to drive the left and right wheels to achieve independent steering. The steering motor is detected to see if it is faulty based on its current / torque signal. When the steering motor on one side fails, the two-way solenoid valve is controlled to be in a power-off state, the two-way solenoid valve is closed, and the hydraulic cylinder is in a closed state, thereby combining with the racks on both sides to control the steering motor on the side without fault to drive the racks on both sides to drive the wheels to achieve normal driving and steering.

6. The control method based on the independent steer-by-wire system according to claim 5, characterized in that: The following steps are also included: When the steering motor on one side fails, the steering angles of the wheels on both sides are not equal and the angle difference is greater than the preset steering angle threshold x, that is, |θleft-θright|>x, the two-way solenoid valve is closed; wherein θleft and θright represent the steering angles of the left wheel and the right wheel respectively, and the positions of the racks on both sides are also different at this time; When the vehicle speed is less than or equal to the preset vehicle speed y and the steering wheel angle is less than the preset angle, the control unit sends a command to energize the two-way solenoid valve to open the valve, and the control unit drives the rack on the side without fault to drive the wheel to achieve the required rotation direction and angle after calculation; When |θleft-θright|<x, the control unit sends a command to close the two-way solenoid valve, combining the gears and racks on both sides into one, and the steering motor on the fault-free side drives the racks on both sides to drive the wheels to achieve normal driving and steering. At the same time, closed-loop verification is performed by detecting the rack travel sensor signal.

7. The control method based on the independent steering-by-wire system according to claim 6, characterized in that: The preset angle threshold x ranges from 8° to 15°.

8. The control method based on the independent steering-by-wire system according to claim 6, characterized in that: The preset vehicle speed y ranges from 15km / h to 25km / h.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 5 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 5 to 7 are implemented.

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