Intelligent vehicle pump and steering motor heterogeneous redundant steering system and control method thereof

Abstract

The invention relates to an intelligent vehicle pump and steering motor heterogeneous redundant steering system and a control method thereof. The steering system comprises a main driving module of a variable-speed pump-driven double-steering power-assisted cylinder, an electronic control module, a control redundancy module, a manpower and unmanned steering redundancy module, a high-pressure source redundancy module, a pipeline redundancy module, a steering mode redundancy module, an overload protection module, a corner precise control module and an unmanned steering redundancy module. According to the steering system, unmanned switching among different steering modes is achieved through the redundant synergistic effect of a plurality of modules so as to deal with hydraulic assembly faults and different driving modes, it is guaranteed that the steering system has the redundant safety function, and the reliability and safety of a vehicle are improved. The system can be switched to the standby system when the main system breaks down, it is ensured that the vehicle continues to keep controllability, the emergency capacity and fault tolerance are enhanced, and accidents caused by single-point faults are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle steering, and in particular to an intelligent vehicle pump and steering motor heterogeneous redundant steering system and a control method thereof. Background Art

[0002] With the continuous advancement of my country's civil infrastructure construction and national defense and military modernization, especially in the fields of heavy transportation, engineering construction and military, the demand for multi-axle vehicles has increased dramatically, which has promoted the rapid development of related technologies. These vehicles usually operate in complex and harsh environments, requiring the steering system to have all-road adaptability, support multiple steering modes, have large load driving capabilities, and provide precise control performance. With its advantages of fast response, high power output and high-precision control, the electro-hydraulic servo steering system has become the first choice for multi-axle vehicle steering systems, especially in military and heavy civilian vehicles.

[0003] The existing hydraulic power steering system has a pump whose power source comes directly from the engine, and its power-assistance characteristics cannot be adjusted with the vehicle speed. It is difficult to meet the differentiated requirements for steering hand force at different vehicle speeds. The steering performance is poor at low speeds, and the steering is "floating" at high speeds. In addition, the traditional single steering system lacks effective redundant safety measures when the hydraulic components fail. When any component such as the pump source or pipeline fails, the steering power will be greatly reduced or even completely lost. This situation may cause the vehicle to lose control and increase the risk of traffic accidents. Therefore, it is necessary to propose an intelligent vehicle pump and steering motor heterogeneous redundant steering system and its control method. Summary of the invention

[0004] The purpose of the present invention is to provide an intelligent vehicle pump and steering motor heterogeneous redundant steering system and a control method thereof. The steering system can achieve multi-mode, high-reliability, and high-precision dynamic steering through redundant design and composite control of each module.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: an intelligent vehicle pump and steering motor heterogeneous redundant steering system, including a main drive module of a variable speed pump-driven dual steering booster cylinder, an electronic control module, a control redundancy module, a manual and unmanned steering redundancy module, a high-voltage source redundancy module, a pipeline redundancy module, a steering mode redundancy module, an overload protection module, a steering angle precision control module and an unmanned steering redundancy module; the main drive module of the variable speed pump-driven dual steering booster cylinder adopts a servo motor pump unit as a pump source; the electronic control module outputs control instructions to control the left and right wheel angles in real time according to the input target angle signal and the signals of the left and right wheel angle sensors; the control redundancy module connects the valve-controlled electro-hydraulic steering submodule and the pump-controlled electro-hydraulic steering submodule in parallel through a hydraulic interlocking circuit to realize the control switching between valve-controlled electro-hydraulic steering and pump-controlled electro-hydraulic steering; the manual and unmanned steering redundancy module realizes unmanned steering by adding a motor assist device under the steering wheel. The switching between human steering mode and manpower steering mode; the high-pressure source redundancy module realizes multi-oil source oil supply guarantee by connecting a large-flow fixed-speed pump and a small-flow variable-speed pump in parallel, and installing an accumulator at the pump outlet; the pipeline redundancy module realizes switching between different pipelines by connecting two ball valves in parallel; the steering mode redundancy module realizes switching between electro-hydraulic coupling steering and electro-hydraulic steering modes by using a power steering motor and a reduction device; the overload protection module limits the pressure inside the steering system; the angle precision control module controls the flow entering the dual steering power cylinder through a servo motor pump unit; the unmanned steering redundancy module is realized by connecting two hydraulic steering gears in parallel with a two-position three-way electromagnetic reversing valve, one of which is connected to the steering wheel through a steering column, and a motor power assist device is installed on the steering column, and the other hydraulic steering gear is connected to the motor through a reduction device, and the motor is controlled by the controller to realize redundancy of the unmanned steering mode.

[0006] Furthermore, the main drive module of the variable speed pump-driven dual steering power cylinder includes two servo motor pump units, which serve as pump sources for the intelligent vehicle pump and steering motor heterogeneous redundant steering system, one of which is composed of a first servo motor and a large-flow quantitative pump, and the other is composed of a second servo motor and a small-flow variable pump; the pressure and flow of the main drive module are controlled by the two servo motor pump units, and the direction is controlled by the electromagnetic reversing valve. The servo motor pump unit adjusts the servo motor speed under the control of the controller to adapt to changes in working pressure and provide flow on demand; the main drive module also includes two overflow unloading valve groups, which are composed of a overflow valve and a two-position two-way electromagnetic reversing valve in parallel.

[0007] Furthermore, the control redundancy module includes a valve-controlled electro-hydraulic steering submodule, a pump-controlled electro-hydraulic steering submodule and a hydraulic interlocking circuit to realize the control switching of valve-controlled electro-hydraulic steering and pump-controlled electro-hydraulic steering; the valve-controlled electro-hydraulic steering submodule includes a servo proportional valve and a locking device to control the dual steering power cylinders; the pump-controlled electro-hydraulic steering submodule includes a hydraulic steering gear, wherein the hydraulic oil circuit runs as follows: from the first oil suction filter to the large-flow quantitative pump or the second oil suction filter to the small-flow variable pump, and then through the two-position three-way solenoid reversing valve, the one-way valve, the steering valve sleeve, the steering valve core, the right inlet of the metering motor, the left outlet of the metering motor, the steering valve sleeve, the A port of the steering power cylinder, the B port of the steering power cylinder, the steering valve sleeve, the steering valve core, the steering valve sleeve, the T port of the steering control valve group to the hydraulic oil tank.

[0008] Furthermore, the manual and unmanned steering redundant module is equipped with a motor assist device under the steering wheel, and the motor assist device is composed of a power steering motor and a reduction device. The reduction device is installed on the steering column under the steering wheel, and the power steering motor is connected to the reduction device, so that the controller controls the power on and off of the motor assist device to realize the switching between the unmanned steering mode and the manual steering mode; in the unmanned driving mode, the controller controls the power steering motor to work, and drives the steering column to rotate through the reduction device. The steering column is connected to the steering valve core of the hydraulic steering gear, so that the steering valve core and the steering valve sleeve of the hydraulic steering gear produce relative displacement, thereby realizing unmanned steering.

[0009] Furthermore, the high-pressure source redundancy module includes a large-flow constant-speed pump and a small-flow variable-speed pump, which are connected in parallel, and an accumulator is installed at the outlet of the parallel pipeline to achieve multi-oil source oil supply guarantee.

[0010] Furthermore, the pipeline redundancy module includes two ball valves, which are connected in parallel and installed on the outlet oil line of the metering pump to achieve switching between different pipelines.

[0011] Furthermore, the steering mode redundancy module realizes the switching between the electro-hydraulic coupled steering and electro-hydraulic steering modes by selecting whether the power steering motor and the reduction device act simultaneously with the steering wheel or act alone. For the electro-hydraulic coupled steering mode, the power steering motor and the reduction device act simultaneously with the steering wheel, and the power steering motor is responsible for the active control of the vehicle and the adjustment of the steering hand torque fed back to the driver, and the vehicle must be in the manual driving mode at this time. For the electro-hydraulic steering mode, only one of the power steering motor and the reduction device and the steering wheel acts: in the manual driving mode, the steering wheel acts alone, while in the unmanned driving mode, the power steering motor and the reduction device act alone.

[0012] Furthermore, the overload protection module includes an overload relief valve and an oil replenishment one-way valve to limit the pressure inside the steering system; the overload protection module is provided with the overload relief valve and the oil replenishment one-way valve, when the ground is uneven and the steering power cylinder piston rod is impacted, the oil pressure in the left or right chamber of the steering power cylinder becomes high, and when the pressure reaches the set pressure of the overload relief valve, the oil in the steering power cylinder flows back to the oil tank through the overload relief valve.

[0013] Furthermore, the steering angle precision control module is implemented by a servo motor pump unit consisting of a servo motor and a small-flow variable pump. The servo motor pump unit adjusts the speed of the servo motor under the control of the controller, and controls the pump flow rate by adjusting the speed of the servo motor and the displacement of the small-flow variable pump, thereby achieving precise control of the flow entering the dual steering power cylinder.

[0014] Furthermore, the unmanned steering redundancy module is realized by connecting two hydraulic steering gears in parallel through a two-position three-way electromagnetic reversing valve, wherein one of the hydraulic steering gears is connected to the steering wheel through a steering column, and a motor assist device is installed on the steering column, and the other hydraulic steering gear is connected to the motor through a reduction device, and the motor is controlled by a controller to achieve redundancy of the unmanned steering mode; the parallel connection of the hydraulic steering gears is realized by a two-position three-way electromagnetic reversing valve, and when the two-position three-way electromagnetic reversing valve is in the left position, the system is in the unmanned driving mode, and when the two-position three-way electromagnetic reversing valve is in the right position, the manual steering mode or the unmanned steering mode is selected through the manual and unmanned steering redundancy module.

[0015] The present invention also provides a control method for the above-mentioned intelligent vehicle pump and steering motor heterogeneous redundant steering system, comprising the following steps: Step S1: Determine whether the system pipeline is in an emergency fault state. If so, jump to step S17; if not, jump to step S2; Step S2: Determine whether the system motor servo pump is in an emergency fault state. If not, jump to step S4; if yes, jump to step S3; Step S3: Set the accumulator valve to open; jump to step S4; Step S4: setting the gain and loss of power of the valve group electromagnet in the switching power-assist interlocking circuit, selecting a control module, including a valve-controlled electro-hydraulic steering submodule and a pump-controlled electro-hydraulic steering submodule, when the three-position four-way solenoid directional valve in the valve group is in the middle position and the two-position three-way solenoid directional valve is in the left position, the pump is unloaded; when the three-position four-way solenoid directional valve in the valve group is in the middle position and the two-position three-way solenoid directional valve is in the right position, the system is in the pump-controlled electro-hydraulic steering mode; when the three-position four-way solenoid directional valve in the valve group is in the left position or the right position, the system is in the valve-controlled electro-hydraulic steering mode; Step S5: setting a mode of the power steering motor, including an electro-hydraulic coupling steering mode during manual driving, a pump-controlled electro-hydraulic steering mode during manual driving, and an unmanned driving mode, wherein when the system is in the electro-hydraulic coupling steering mode, the power steering motor is responsible for active control of the vehicle and adjustment of the steering hand torque fed back to the driver, when the system is in the pump-controlled electro-hydraulic steering mode of the manual driving mode, the power steering motor does not function, and when the system is in the unmanned driving mode, the power steering motor acts as a steering wheel; Step S6: The steering system inputs the left and right target turning angle signals of the controlled steering axle into the controller; Step S7: Determine whether the left wheel steering angle deviation signal is greater than the critical steering angle threshold 1: If it is greater than the critical steering angle threshold 1, the controller uses the target steering angle signals of the left and right wheels as two control targets to control the system and jumps to S8; if it is less than the critical steering angle threshold 1, jump to step S12; Step S8: Detecting the actual turning angles of the left and right wheels of the controlled steering bridge, and calculating the deviations between the actual turning angles of the left and right wheels and the target turning angles respectively; Step S9: According to the deviation signal between the target turning angle of the left wheel and the current turning angle, the controller sends a signal to the servo motor and the electromagnetic reversing valve corresponding to the large flow quantitative pump to control their operation; according to the deviation signal between the target turning angle of the right wheel and the current turning angle, the servo proportional valve is controlled to operate; and the process jumps to step S10; Step S10: The controller sends a control signal to the corresponding components to control the extension and retraction of the steering cylinder so that the left wheel or the right wheel reaches the target turning angle; Step S11: Determine whether the left wheel steering angle deviation signal is greater than the critical steering angle threshold 1: if greater, jump to step S7; if less than; the critical steering angle threshold 1 jump to step S12; Step S12: Determine whether the left wheel steering angle deviation signal is greater than the critical steering angle threshold 2: if greater, jump to step S13; if less than; the critical steering angle threshold 2 jump to step S16; Step S13: According to the deviation signal between the target turning angle of the left wheel and the current turning angle, the controller sends a signal to the servo motor and the electromagnetic reversing valve corresponding to the small flow variable pump to control their operation; according to the deviation signal between the target turning angle of the right wheel and the current turning angle, the servo proportional valve or the motor is controlled to operate; and the process jumps to step S14; Step S14: The controller sends a control signal to the corresponding components to control the extension and retraction of the steering cylinder so that the left wheel or the right wheel reaches the target turning angle; Step S15: Determine whether the left wheel steering angle deviation signal is greater than the critical steering angle threshold 2: if greater, jump to step S13; if less than the critical steering angle threshold 2, jump to step S16; (critical steering angle threshold 1 is used for selecting and switching between large and small flow pumps; critical steering angle threshold 2 is used to determine whether to end) Step S16: Set the servo proportional valve to the middle position, the two-position three-way electromagnetic reversing valve is energized, the pilot oil of the hydraulically controlled one-way valve group is returned to the oil chamber, and the steering cylinder is locked; jump to step 21; Step S17: the controller sends out an alarm signal; Step S18: Synchronously with step S17, the steering system inputs the left and right target turning angle signals of the controlled steering axle into the controller; Step S19: setting the switch status of the two parallel ball valves; Step S20: setting the emergency servo proportional valve to the left position or the right position; Step S21: The servo motor changes the motor speed through the voltage control signal to adjust the output flow and pressure of the quantitative pump; the electromagnetic reversing valve is controlled by using the angular velocity feedforward angle feedback control, and the left turn is set as positive. The deviation angle between the target angle and the actual angle of the left steering wheel is used as the feedback signal, the target angular velocity is used as the feedforward signal, and the sum of the feedback signal and the feedforward signal is used as the control signal. The control signal function is as follows: U=(θq-θs)+ωq Among them, U is the control signal, θq is the target angle, θs is the actual angle, and ωq is the target angular velocity.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides an intelligent vehicle pump and steering motor heterogeneous redundant steering system and a control method thereof. The steering system realizes unmanned switching between different steering modes through the synergistic effect of multiple module redundancies to cope with different situations of hydraulic component failure and driving modes, ensures that the steering system has redundant safety functions, and improves the reliability and safety of the vehicle. It can switch to the backup system unmanned when the main system fails, ensure that the vehicle continues to maintain controllability, enhance emergency response capabilities and fault tolerance, and avoid accidents caused by single point failures. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of the structure of a heterogeneous redundant steering system of an intelligent vehicle pump and a steering motor according to an embodiment of the present invention; Figure 2 The present invention is a flowchart of a control method for a heterogeneous redundant steering system of an intelligent vehicle pump and a steering motor according to an embodiment of the present invention.

[0018] In the figure: 1. Oil tank; 2. Stop valve; 3. Filter; 4. Large flow metering pump; 5. Pilot overflow unloading valve group; 6. Parallel ball valve; 6.1 Branch ball valve; 6.2 Main ball valve; 7. Servo proportional valve; 8. Position sensor; 9. Check valve; 10. Accumulator; 11. Flow meter; 12. Power-assisted switching interlocking valve group; 12.1 Three-position four-way solenoid reversing valve; 12.2 Two-position three-way solenoid reversing valve; 13. Servo proportional valve; 14. Position sensor; 15. Hydraulic control check valve group; 16. Left steering wheel; 17. Left wheel angle sensor; 18. Frame; 19 , steering cylinder; 20, flow meter; 21, flow meter; 22, angle sensor; 23, torque sensor; 24, steering wheel; 25, electric power steering device; 25.1, power steering motor; 25.2, speed reducer; 26, steering column; 27, hydraulic steering gear; 27.1, first overload relief valve; 27.2, second overload relief valve; 27.3, first oil replenishment check valve; 27.4, second oil replenishment check valve; 27.5, metering motor; 27.6, steering valve sleeve; 27.7, steering valve core; 27.8, check valve; 27.9, relief valve; 2 7.10, one-way valve; 28, right steering wheel; 29, flow meter; 30, right wheel angle sensor; 31, flow meter; 32, flow meter; 33, flow meter; 34, relief valve; 35, one-way valve; 36, two-position two-way electromagnetic reversing valve; 37, relief valve; 38, one-way valve; 39, two-position two-way electromagnetic reversing valve; 40, two-position three-way electromagnetic reversing valve; 41, flow meter; 42, one-way valve; 43, one-way valve; 44, pilot overflow unloading valve group; 45, second servo motor; 46, small flow variable pump; 47, first servo motor; 48, filter; 49, Stop valve; 50, one-way valve; 51, overflow valve; 52, overflow valve; 53, one-way valve; 54, hydraulic steering gear; 54.1, first overload overflow valve; 54.2, second overload overflow valve; 54.3, first oil replenishment one-way valve; 54.4, second oil replenishment one-way valve; 54.5, metering motor; 54.6, steering valve sleeve; 54.7, steering valve core; 54.8, one-way valve; 54.9, overflow valve; 54.10, one-way valve; 55, unmanned electric steering device; 55.1, servo motor; 55.2, speed reduction device; 56, two-position three-way electromagnetic reversing valve. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0020] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0021] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0022] like Figure 1 As shown, this embodiment provides a heterogeneous redundant steering system of an intelligent vehicle pump and steering motor, including a main drive module of a variable speed pump-driven dual steering cylinder, an electronic control module, a control redundancy module, a manual and unmanned steering redundancy module, a high-voltage source redundancy module, a pipeline redundancy module, a steering mode redundancy module, an overload protection module, a corner precision control module and an unmanned steering redundancy module.

[0023] The main drive module of the variable speed pump-driven dual steering cylinder adopts a servo motor pump unit as a pump source.

[0024] Specifically, the main drive module of the variable speed pump-driven dual steering cylinder includes an oil tank 1, a stop valve 2, a filter 3, a large flow quantitative pump 4, a one-way valve 42, a first servo motor 47, a stop valve 49, a filter 48, a small flow variable pump 46, a second servo motor 45, and a one-way valve 43.

[0025] The main drive module of the variable speed pump driven dual steering cylinder includes two servo motor pump units as the pump source of the intelligent vehicle pump and the steering motor heterogeneous redundant steering system; wherein the first servo motor pump unit 1 is composed of the first servo motor 47 and the large flow quantitative pump 4, the large flow quantitative pump is used when the vehicle steering angle is large, so that the system can provide more flow more quickly, and the second servo motor pump unit 2 is composed of the second servo motor 45 and the small flow variable pump 46, the small flow variable pump is used for more precise control of the angle. The pressure and flow of the main drive module are controlled by the servo motor pump unit, and the direction is controlled by the electromagnetic reversing valve. The servo motor pump unit adjusts the speed of the first servo motor 47 or the second servo motor 45 under the control of the controller to adapt to the change of working pressure and provide flow on demand. The main drive module also includes two overflow unloading valve groups, which are composed of a overflow valve and a two-position two-way electromagnetic reversing valve in parallel.

[0026] The electronic control module outputs control instructions to control the left and right wheel angles in real time according to the input target angle signal and the signals of the left and right wheel angle sensors.

[0027] Specifically, the electronic control module includes a controller, a first servo motor 47, a second servo motor 45, a left wheel angle sensor 17, a right wheel angle sensor 30, a rotation angle sensor 22 and a torque sensor 23. The controller is respectively connected to the servo proportional valve 7, the position sensor 8, the power switching interlock valve group 12, the servo proportional valve 13, the position sensor 14, the left wheel angle sensor 17, the rotation angle sensor 22, the torque sensor 23, the power steering motor 25.1, the electromagnetic reversing valve 36, the electromagnetic reversing valve 39 and the electromagnetic reversing valve 40. The left and right wheel angle sensors are connected to the controller to calculate the deviation between the target rotation angle of the left and right steering wheels and the actual rotation angle, and send real-time control signals to the first servo motor 47 or the second servo motor 45, the servo proportional valve 13, the electromagnetic reversing valve 36, the electromagnetic reversing valve 39, the electromagnetic reversing valve 40 and the power steering motor 25.1 according to the calculation results.

[0028] The control redundancy module connects the valve-controlled electro-hydraulic steering submodule and the pump-controlled electro-hydraulic steering submodule in parallel via a hydraulic interlocking circuit to achieve control switching between the valve-controlled electro-hydraulic steering and the pump-controlled electro-hydraulic steering.

[0029] Specifically, the control redundancy module includes a power-assisted switching interlocking valve group 12 , a servo proportional valve 13 , a position sensor 14 , a hydraulic lock 15 and a hydraulic steering gear 27 .

[0030] The control redundancy module includes a valve-controlled electro-hydraulic steering submodule, a pump-controlled electro-hydraulic steering submodule and a hydraulic interlocking circuit to realize the control switching between valve-controlled electro-hydraulic steering and pump-controlled electro-hydraulic steering; the valve-controlled electro-hydraulic steering submodule includes a servo proportional valve and a locking device to control the left and right steering cylinders; the pump-controlled electro-hydraulic steering submodule includes a hydraulic steering gear, wherein the hydraulic oil circuit runs from the first oil suction filter to the large-flow quantitative pump or the second oil suction filter to the small-flow variable pump, and then through the two-position three-way electromagnetic reversing valve, the one-way valve, the steering valve sleeve, the steering valve core, the right inlet of the metering motor, the left outlet of the metering motor, the steering valve sleeve, the A port of the steering cylinder, the B port of the steering cylinder, the steering valve sleeve, the steering valve core, the steering valve sleeve, the T port of the steering control valve group to the hydraulic oil tank.

[0031] The control redundancy module realizes pump-controlled electro-hydraulic steering control and valve-controlled electro-hydraulic steering control by controlling the two electromagnetic reversing valves in the power-assisted switching interlock valve group 12. In the pump-controlled electro-hydraulic steering control mode, by controlling the power-assisted steering motor 25.1 and the steering wheel 24, switching between three modes, namely, human-driven electro-hydraulic coupled steering mode, human-driven pump-controlled electro-hydraulic steering mode and unmanned driving steering mode, can be realized.

[0032] The pump-controlled electro-hydraulic steering submodule manual left steering hydraulic module includes a hydraulic steering gear 26 and a steering valve core 27.7. The driver turns the steering wheel to the left position of the steering valve core 27.7. When greater power assistance is required, the hydraulic oil circuit of the manual left steering hydraulic module goes from the stop valve 2 to the filter 3 to the large-flow metering pump 4 to the one-way valve 27.10 to the steering valve sleeve 27.6 (left position) to the steering valve core 27.7 (left position) to the right inlet of the metering motor 27.5 to the left outlet of the metering motor 27.5 to the steering valve sleeve 27.6 (left position) to the steering power cylinder 19B port to the steering power cylinder 19A port to the steering valve sleeve 27.6 (left position) to the steering valve core 27.6 (left position) to the steering valve sleeve 27.6 (left position) to the steering gear 27T port to the hydraulic oil tank.

[0033] The manual and unmanned steering redundancy module realizes the switching between the unmanned steering mode and the manual steering mode by adding a motor assist device to the steering wheel.

[0034] Specifically, the motor assist device installed on the steering wheel of the manual and unmanned steering redundancy module includes a power steering motor 25.1 and a speed reducer 25.2. The speed reducer 25.2 is installed on the steering column under the steering wheel, and the power steering motor 25.1 is connected to the speed reducer 25.2, so that the switching between the unmanned steering mode and the manual steering mode is realized by controlling the power on and off of the motor assist device through the controller.

[0035] In the unmanned driving mode, the controller controls the power steering motor to work, and drives the steering column to rotate through the reduction device. The steering column is connected to the steering valve core of the hydraulic steering gear, so that the steering valve core and the steering valve sleeve of the hydraulic steering gear produce relative displacement, thereby realizing unmanned steering.

[0036] The high-pressure source redundancy module realizes oil supply guarantee from multiple oil sources by connecting a large-flow fixed-speed pump and a small-flow variable-speed pump in parallel and installing an accumulator at the pump outlet.

[0037] Specifically, the high-pressure source redundancy module includes a large-flow constant-speed pump 4, a small-flow variable-speed pump 46 and an accumulator 10. After the large-flow constant-speed pump 4 and the small-flow variable-speed pump 46 are connected in parallel, an accumulator is installed at the outlet of the parallel pipeline to serve as an emergency power source when the pump source fails, thereby achieving multi-oil source oil supply guarantee.

[0038] The pipeline redundancy module is connected in parallel through two ball valves to achieve switching between different pipelines.

[0039] Specifically, the pipeline redundancy module includes two parallel ball valves 6, which are connected in parallel and installed on the outlet oil line of the metering pump. By controlling the opening and closing of the two ball valves, switching of different pipelines is achieved.

[0040] The steering mode redundancy module realizes the switching between the electro-hydraulic coupled steering mode and the electro-hydraulic steering mode through the power steering motor and the reduction device.

[0041] Specifically, the steering mode redundancy module realizes the switching between the electro-hydraulic coupling steering and the electro-hydraulic steering modes by selecting whether the power steering motor 25.1 and the speed reducer 25.2 act on the steering wheel simultaneously or individually. The steering mode redundancy module realizes the switching between the electro-hydraulic coupling steering and the electro-hydraulic steering modes by selecting whether the power steering motor and the speed reducer act on the steering wheel simultaneously or individually. For the electro-hydraulic coupling steering mode, the power steering motor and the speed reducer act on the steering wheel simultaneously. The power steering motor is only responsible for the active control of the vehicle and the adjustment of the steering hand torque fed back to the driver in the manual steering mode, and must be in the manual driving mode at this time. For the electro-hydraulic steering mode, only one of the power steering motor and the speed reducer and the steering wheel works: in the manual driving mode, the steering wheel works alone, and in the unmanned driving mode, the power steering motor and the speed reducer work alone. The power steering motor does not work or acts as a steering wheel in the unmanned driving mode.

[0042] The overload protection module limits the pressure inside the steering system.

[0043] Specifically, the overload protection module includes a first overload relief valve 27.1, a second overload relief valve 27.2, a first oil replenishment check valve 27.3 and a second oil replenishment check valve 27.4.

[0044] The overload protection module is provided with an overload relief valve and an oil replenishment one-way valve. When the ground is uneven and the piston rod of the steering power cylinder is impacted, the oil pressure in the left or right chamber of the steering power cylinder becomes high. When the pressure reaches the set pressure of the overload relief valve, the oil in the steering power cylinder flows back to the oil tank through the overload relief valve.

[0045] The steering angle precision control module controls the flow entering the dual steering power cylinders through a servo motor pump unit.

[0046] Specifically, the steering angle precision control module is implemented by a second servo motor pump unit consisting of a servo motor 47 and a small flow variable pump 46. The second servo motor pump unit adjusts the speed of the servo motor 47 under the control of the controller, and controls the pump flow rate by adjusting the speed of the servo motor 47 and the displacement of the small flow variable pump 46, thereby realizing precise control of the flow entering the dual steering cylinders.

[0047] Furthermore, the steering angle precision control module is implemented by a servo motor pump unit consisting of a servo motor and a small-flow variable pump. The servo motor pump unit adjusts the speed of the servo motor under the control of the controller, and controls the pump flow rate by adjusting the speed of the servo motor and the displacement of the small-flow variable pump, thereby achieving precise control of the flow entering the dual steering power cylinder.

[0048] The unmanned steering redundancy module realizes the redundancy of the unmanned steering mode by connecting two hydraulic steering gears in parallel.

[0049] Specifically, the unmanned steering redundant module is implemented by the hydraulic steering gear 27, the hydraulic steering gear 54, the power steering motor 25.1, the speed reducer 25.2, the servo motor 55.1, the speed reducer 55.2 and the two-position three-way electromagnetic reversing valve 56. The two-position three-way electromagnetic reversing valve 56 realizes the left (right) position switching under the control of the controller, and then realizes the selection of the unmanned steering mode. The two-position three-way electromagnetic reversing valve 56 is in the left position. At this time, the power steering motor 25.1 starts to work under the control of the controller, and the oil enters the steering power cylinder through the hydraulic steering gear 27 to realize the left (right) unmanned steering; the two-position three-way electromagnetic reversing valve 56 is in the right position. At this time, under the control of the controller, the servo motor 55.1 starts to work, and the oil enters the steering power cylinder through the hydraulic steering gear 27 to realize the left (right) unmanned steering.

[0050] Preferably, the power steering motor is connected to a power steering motor controller for receiving an ECU control signal and directly controlling the power steering motor. The power steering motor switches between a manual steering mode and an unmanned driving mode according to a control signal provided by the ECU. In the manual steering mode, when the driver turns the steering wheel, when the steering wheel turns right (or left), the valve core is driven to turn right (or left). Since there is a certain amount of rotation between the valve core and the valve sleeve (determined by the model of the steering gear, up to 10.5° in this embodiment), the valve core will overcome the spring between the valve core sleeve. The elastic force of the plate causes the valve core to rotate relative to the valve sleeve. At this time, the valve core oil groove is connected to the oil inlet of the valve sleeve. The oil from the pump flows through the valve sleeve, the valve core oil groove, and then from the valve sleeve to the rotor and the stator, pushing the rotor to rotate relative to the stator. At the same time, the oil output from the rotor and the stator passes through the valve sleeve and then enters one chamber of the steering power cylinder through the oil port A (or B), causing the cylinder piston rod to extend (retract), pushing the steering wheel to turn right (or left), and the oil in the other chamber of the cylinder enters the valve sleeve from the oil port B (or A), and then passes through the valve core's oil return groove, and then returns to the oil tank from the valve sleeve's oil return hole through the oil port T, thereby realizing the steering function. When the valve core and the valve sleeve have a certain relative rotation angle (about 1.5° in this embodiment), the oil circuit starts to connect, and the rotation of the rotor causes the oil to flow to the oil cylinder. The amount of oil supplied is proportional to the rotation angle of the steering wheel. In the unmanned driving mode, the stator of the power steering motor 25.1 is energized by the controller to generate a rotating magnetic field, and the rotating magnetic field drives the rotor of the power steering motor 25.1 to rotate, and drives the steering column to rotate left (right) through the reduction device 25.2. The steering column is directly connected to the valve core, and the rotation of the steering column drives the valve core to rotate left (right). Because there is a certain amount of rotation between the valve core and the valve sleeve (determined by the model of the steering gear, and in this embodiment, the maximum is 10.5°), the valve core will overcome the elastic force of the spring sheet between the valve core sleeve, so the valve core is relative to the valve. The sleeve rotates, and the oil groove of the valve core is connected with the oil inlet of the valve sleeve. The oil from the pump flows through the valve sleeve, the oil groove of the valve core, and then from the valve sleeve to the rotor and the stator, pushing the rotor to rotate relative to the stator. At the same time, the oil output from the rotor and the stator passes through the valve sleeve and then enters one chamber of the steering cylinder through the oil port A (or B), so that the cylinder piston rod extends (retracts), pushing the steering wheel to turn right (or left), and the oil in the other chamber of the cylinder enters the valve sleeve from the oil port B (or A), and then passes through the oil return groove of the valve core, and then returns to the oil tank from the oil return hole of the valve sleeve through the oil port T, thereby realizing the steering function; when the valve core and the valve sleeve have a certain relative rotation angle (about 1.5° in this embodiment), the oil circuit begins to be connected, and the rotation of the rotor causes the oil to flow to the cylinder, and the amount of oil supply is proportional to the angle of the steering wheel.

[0051] Preferably, a rotation angle sensor and a torque sensor are installed at the upper end of the steering shaft and below the steering wheel. The rotation angle torque sensor is used to obtain a rotation angle signal and a torque signal, and transmit the rotation angle signal and the torque signal to the ECU.

[0052] like Figure 2As shown, this embodiment also provides a control method for the above-mentioned intelligent vehicle pump and steering motor heterogeneous redundant steering system, including the following steps: Step S1: Determine whether the system pipeline is in an emergency fault state. If so, jump to step S17; if not, jump to step S2; Step S2: Determine whether the system motor servo pump is in an emergency fault state. If not, jump to step S4; if yes, jump to step S3; Step S3: Set the accumulator valve to open; jump to step S4; Step S4: setting the gain and loss of power of the valve group electromagnet in the switching power-assist interlocking circuit, selecting a control module, including a valve-controlled electro-hydraulic steering submodule and a pump-controlled electro-hydraulic steering submodule, when the three-position four-way solenoid directional valve in the valve group is in the middle position and the two-position three-way solenoid directional valve is in the left position, the pump is unloaded; when the three-position four-way solenoid directional valve in the valve group is in the middle position and the two-position three-way solenoid directional valve is in the right position, the system is in the pump-controlled electro-hydraulic steering mode; when the three-position four-way solenoid directional valve in the valve group is in the left position or the right position, the system is in the valve-controlled electro-hydraulic steering mode; Step S5: setting a mode of the power steering motor, including an electro-hydraulic coupling steering mode during manual driving, a pump-controlled electro-hydraulic steering mode during manual driving, and an unmanned driving mode, wherein when the system is in the electro-hydraulic coupling steering mode, the power steering motor is responsible for active control of the vehicle and adjustment of the steering hand torque fed back to the driver, when the system is in the pump-controlled electro-hydraulic steering mode of the manual driving mode, the power steering motor does not function, and when the system is in the unmanned driving mode, the power steering motor acts as a steering wheel; Step S6: The steering system inputs the left and right target turning angle signals of the controlled steering axle into the controller; Step S7: Determine whether the left wheel steering angle deviation signal is greater than the critical steering angle threshold 1: If it is greater than the critical steering angle threshold 1, the controller uses the target steering angle signals of the left and right wheels as two control targets to control the system and jumps to S8; if it is less than the critical steering angle threshold 1, jump to step S12; Step S8: Detecting the actual turning angles of the left and right wheels of the controlled steering bridge, and calculating the deviations between the actual turning angles of the left and right wheels and the target turning angles respectively; Step S9: According to the deviation signal between the target turning angle of the left wheel and the current turning angle, the controller sends a signal to the servo motor and the electromagnetic reversing valve corresponding to the large flow quantitative pump to control their operation; according to the deviation signal between the target turning angle of the right wheel and the current turning angle, the servo proportional valve is controlled to operate; and the process jumps to step S10; Step S10: The controller sends a control signal to the corresponding components to control the extension and retraction of the steering cylinder so that the left wheel or the right wheel reaches the target turning angle; Step S11: Determine whether the left wheel steering angle deviation signal is greater than the critical steering angle threshold 1: if greater, jump to step S7; if less than; the critical steering angle threshold 1 jump to step S12; Step S12: Determine whether the left wheel steering angle deviation signal is greater than the critical steering angle threshold 2: if greater, jump to step S13; if less than; the critical steering angle threshold 2 jump to step S16; Step S13: According to the deviation signal between the target turning angle of the left wheel and the current turning angle, the controller sends a signal to the servo motor and the electromagnetic reversing valve corresponding to the small flow variable pump to control their operation; according to the deviation signal between the target turning angle of the right wheel and the current turning angle, the servo proportional valve or the motor is controlled to operate; and the process jumps to step S14; Step S14: The controller sends a control signal to the corresponding components to control the extension and retraction of the steering cylinder so that the left wheel or the right wheel reaches the target turning angle; Step S15: Determine whether the left wheel steering angle deviation signal is greater than the critical steering angle threshold 2: if greater, jump to step S13; if less than the critical steering angle threshold 2, jump to step S16; (critical steering angle threshold 1 is used for selecting and switching between large and small flow pumps; critical steering angle threshold 2 is used to determine whether to end) Step S16: Set the servo proportional valve to the middle position, the two-position three-way electromagnetic reversing valve is energized, the pilot oil of the hydraulically controlled one-way valve group is returned to the oil chamber, and the steering cylinder is locked; jump to step 21; Step S17: the controller sends out an alarm signal; Step S18: Synchronously with step S17, the steering system inputs the left and right target turning angle signals of the controlled steering axle into the controller; Step S19: setting the switch status of the two parallel ball valves; Step S20: setting the emergency servo proportional valve to the left position or the right position; Step S21: The servo motor changes the motor speed through the voltage control signal to adjust the output flow and pressure of the quantitative pump; the electromagnetic reversing valve is controlled by using the angular velocity feedforward angle feedback control, and the left turn is set as positive. The deviation angle between the target angle and the actual angle of the left steering wheel is used as the feedback signal, the target angular velocity is used as the feedforward signal, and the sum of the feedback signal and the feedforward signal is used as the control signal. The control signal function is as follows: U=(θq-θs)+ωq Among them, U is the control signal, θq is the target angle, θs is the actual angle, and ωq is the target angular velocity.

[0053] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. An intelligent vehicle pump and steering motor heterogeneous redundant steering system, characterized in that: It includes a main drive module of a variable speed pump-driven dual steering cylinder, an electronic control module, a control redundancy module, a manual and unmanned steering redundancy module, a high-voltage source redundancy module, a pipeline redundancy module, a steering mode redundancy module, an overload protection module, a corner precision control module and an unmanned steering redundancy module; the main drive module of the variable speed pump-driven dual steering cylinder adopts a servo motor pump unit as a pump source; the electronic control module outputs control instructions to control the left and right wheel angles in real time according to the input target angle signal and the signals of the left and right wheel angle sensors; the control redundancy module connects the valve-controlled electro-hydraulic steering submodule and the pump-controlled electro-hydraulic steering submodule in parallel through a hydraulic interlocking circuit to realize the control switching between valve-controlled electro-hydraulic steering and pump-controlled electro-hydraulic steering; the manual and unmanned steering redundancy module realizes the switching between unmanned steering mode and manual steering mode by adding a motor assist device under the steering wheel; the high-voltage source The redundancy module realizes multi-oil supply guarantee by connecting a large-flow fixed-speed pump and a small-flow variable-speed pump in parallel and installing an accumulator at the pump outlet; the pipeline redundancy module realizes switching between different pipelines by connecting two ball valves in parallel; the steering mode redundancy module realizes switching between electro-hydraulic coupling steering and electro-hydraulic steering modes by using a power steering motor and a reduction device; the overload protection module limits the pressure inside the steering system; the angle precision control module controls the flow entering the dual steering power cylinder by a servo motor pump unit; the unmanned steering redundancy module is realized by connecting two hydraulic steering gears in parallel through a two-position three-way electromagnetic reversing valve, one of which is connected to the steering wheel through a steering column, and a motor power assist device is installed on the steering column, and the other hydraulic steering gear is connected to the motor through a reduction device, and the motor is controlled by a controller to realize redundancy of the unmanned steering mode.

2. The intelligent vehicle pump and steering motor heterogeneous redundant steering system according to claim 1 is characterized in that: The main drive module of the variable speed pump-driven dual steering power cylinder includes two servo motor pump units, which serve as pump sources for the intelligent vehicle pump and steering motor heterogeneous redundant steering system, one of which is composed of a first servo motor and a large-flow quantitative pump, and the other is composed of a second servo motor and a small-flow variable pump; the pressure and flow of the main drive module are controlled by the two servo motor pump units, and the direction is controlled by the electromagnetic reversing valve. The servo motor pump unit adjusts the servo motor speed under the control of the controller to adapt to changes in working pressure and provide flow on demand; the main drive module also includes two overflow unloading valve groups, which are composed of a overflow valve and a two-position two-way electromagnetic reversing valve in parallel.

3. The intelligent vehicle pump and steering motor heterogeneous redundant steering system according to claim 1, characterized in that: The control redundancy module includes a valve-controlled electro-hydraulic steering submodule, a pump-controlled electro-hydraulic steering submodule and a hydraulic interlocking circuit to realize the control switching between valve-controlled electro-hydraulic steering and pump-controlled electro-hydraulic steering; the valve-controlled electro-hydraulic steering submodule includes a servo proportional valve and a locking device to control the dual steering cylinders; the pump-controlled electro-hydraulic steering submodule includes a hydraulic steering gear, wherein the hydraulic oil circuit runs from the first oil suction filter to the large-flow quantitative pump or the second oil suction filter to the small-flow variable pump, and then through the two-position three-way electromagnetic reversing valve, the one-way valve, the steering valve sleeve, the steering valve core, the right inlet of the metering motor, the left outlet of the metering motor, the steering valve sleeve, the A port of the steering cylinder, the B port of the steering cylinder, the steering valve sleeve, the steering valve core, the steering valve sleeve, the T port of the steering control valve group to the hydraulic oil tank.

4. The intelligent vehicle pump and steering motor heterogeneous redundant steering system according to claim 1, characterized in that: The manual and unmanned steering redundant module is equipped with a motor assist device under the steering wheel. The motor assist device is composed of a power steering motor and a reduction device. The reduction device is installed on the steering column under the steering wheel. The power steering motor is connected to the reduction device, so that the controller controls the power on and off of the motor assist device to realize the switching between the unmanned steering mode and the manual steering mode; in the unmanned driving mode, the controller controls the power steering motor to work, drives the steering column to rotate through the reduction device, and the steering column is connected to the steering valve core of the hydraulic steering gear, so that the steering valve core and the steering valve sleeve of the hydraulic steering gear produce relative displacement, thereby realizing unmanned steering.

5. The intelligent vehicle pump and steering motor heterogeneous redundant steering system according to claim 1, characterized in that: The high-pressure source redundancy module includes a large-flow constant-speed pump and a small-flow variable-speed pump, which are connected in parallel, and an accumulator is installed at the outlet of the parallel pipeline to achieve multi-oil source oil supply guarantee.

6. The intelligent vehicle pump and steering motor heterogeneous redundant steering system according to claim 1, characterized in that: The steering mode redundancy module realizes the switching between the electro-hydraulic coupled steering and electro-hydraulic steering modes by selecting the power steering motor and the reduction device to act simultaneously with the steering wheel or to act alone; For the electro-hydraulic coupling steering mode, the power steering motor and the reduction device act simultaneously with the steering wheel. The power steering motor is responsible for the active control of the vehicle and the adjustment of the steering hand torque fed back to the driver. At this time, the vehicle must be in the human driving mode. For the electro-hydraulic steering mode, only one of the power steering motor, the reduction device and the steering wheel works: in the manual driving mode, the steering wheel works alone, while in the unmanned driving mode, the power steering motor and the reduction device work alone.

7. The intelligent vehicle pump and steering motor heterogeneous redundant steering system according to claim 1, characterized in that: The overload protection module includes an overload relief valve and an oil replenishment one-way valve to limit the pressure inside the steering system; the overload protection module is provided with the overload relief valve and the oil replenishment one-way valve. When the ground is uneven and the piston rod of the steering power cylinder is impacted, the oil pressure in the left or right chamber of the steering power cylinder becomes high. When the pressure reaches the set pressure of the overload relief valve, the oil in the steering power cylinder flows back to the oil tank through the overload relief valve.

8. The intelligent vehicle pump and steering motor heterogeneous redundant steering system according to claim 1, characterized in that: The steering angle precision control module is realized by a servo motor pump unit consisting of a servo motor and a small flow variable pump. The servo motor pump unit adjusts the speed of the servo motor under the control of the controller, and controls the pump flow rate by adjusting the speed of the servo motor and the displacement of the small flow variable pump, thereby realizing precise control of the flow entering the dual steering power cylinder.

9. The intelligent vehicle pump and steering motor heterogeneous redundant steering system according to claim 1, characterized in that: The unmanned steering redundancy module is realized by connecting two hydraulic steering gears in parallel through a two-position three-way electromagnetic reversing valve, wherein one hydraulic steering gear is connected to the steering wheel through a steering column, and a motor power assist device is installed on the steering column, and the other hydraulic steering gear is connected to the motor through a reduction device, and the motor is controlled by a controller to realize the redundancy of the unmanned steering mode; the parallel connection of the hydraulic steering gears is realized by a two-position three-way electromagnetic reversing valve, when the two-position three-way electromagnetic reversing valve is in the left position, the system is in the unmanned driving mode, and when the two-position three-way electromagnetic reversing valve is in the right position, the manual steering mode or the unmanned steering mode is selected through the manual and unmanned steering redundancy module.

10. The control method of the intelligent vehicle pump and steering motor heterogeneous redundant steering system according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step S1: Determine whether the system pipeline is in an emergency fault state. If so, jump to step S17; if not, jump to step S2; Step S2: Determine whether the system motor servo pump is in an emergency fault state, if not, jump to step S4; If yes, jump to step S3; Step S3: setting the accumulator valve to open; Jump to step S4; Step S4: setting the gain and loss of power of the valve group electromagnet in the switching power-assist interlocking circuit, selecting a control module, including a valve-controlled electro-hydraulic steering submodule and a pump-controlled electro-hydraulic steering submodule, when the three-position four-way solenoid directional valve in the valve group is in the middle position and the two-position three-way solenoid directional valve is in the left position, the pump is unloaded; when the three-position four-way solenoid directional valve in the valve group is in the middle position and the two-position three-way solenoid directional valve is in the right position, the system is in the pump-controlled electro-hydraulic steering mode; when the three-position four-way solenoid directional valve in the valve group is in the left position or the right position, the system is in the valve-controlled electro-hydraulic steering mode; Step S5: setting a mode of the power steering motor, including an electro-hydraulic coupling steering mode during manual driving, a pump-controlled electro-hydraulic steering mode during manual driving, and an unmanned driving mode, wherein when the system is in the electro-hydraulic coupling steering mode, the power steering motor is responsible for active control of the vehicle and adjustment of the steering hand torque fed back to the driver, when the system is in the pump-controlled electro-hydraulic steering mode of the manual driving mode, the power steering motor does not function, and when the system is in the unmanned driving mode, the power steering motor acts as a steering wheel; Step S6: The steering system inputs the left and right target turning angle signals of the controlled steering axle into the controller; Step S7: Determine whether the left wheel steering angle deviation signal is greater than the critical steering angle threshold 1: If it is greater than the critical steering angle threshold 1, the controller uses the target steering angle signals of the left and right wheels as two control targets to control the system and jumps to S8; if it is less than the critical steering angle threshold 1, jump to step S12; Step S8: Detecting the actual turning angles of the left and right wheels of the controlled steering bridge, and calculating the deviations between the actual turning angles of the left and right wheels and the target turning angles respectively; Step S9: According to the deviation signal between the target turning angle of the left wheel and the current turning angle, the controller sends a signal to the servo motor and the electromagnetic reversing valve corresponding to the large flow quantitative pump to control their operation; according to the deviation signal between the target turning angle of the right wheel and the current turning angle, the servo proportional valve is controlled to operate; and the process jumps to step S10; Step S10: The controller sends a control signal to the corresponding components to control the extension and retraction of the steering cylinder so that the left wheel or the right wheel reaches the target turning angle; Step S11: Determine whether the left wheel steering angle deviation signal is greater than the critical steering angle threshold 1: if greater, jump to step S7; if less than; the critical steering angle threshold 1 jump to step S12; Step S12: Determine whether the left wheel steering angle deviation signal is greater than the critical steering angle threshold 2: if greater, jump to step S13; if less than; the critical steering angle threshold 2 jump to step S16; Step S13: According to the deviation signal between the target turning angle of the left wheel and the current turning angle, the controller sends a signal to the servo motor and the electromagnetic reversing valve corresponding to the small flow variable pump to control their operation; according to the deviation signal between the target turning angle of the right wheel and the current turning angle, the servo proportional valve or the motor is controlled to operate; and the process jumps to step S14; Step S14: The controller sends a control signal to the corresponding components to control the extension and retraction of the steering cylinder so that the left wheel or the right wheel reaches the target turning angle; Step S15: Determine whether the left wheel steering angle deviation signal is greater than the critical steering angle threshold 2: if greater, jump to step S13; if less than the critical steering angle threshold 2, jump to step S16; (critical steering angle threshold 1 is used for selecting and switching between large and small flow pumps; critical steering angle threshold 2 is used to determine whether to end) Step S16: Set the servo proportional valve to the middle position, the two-position three-way electromagnetic reversing valve is energized, the pilot oil of the hydraulically controlled one-way valve group is returned to the oil chamber, and the steering cylinder is locked; jump to step 21; Step S17: the controller sends out an alarm signal; Step S18: Synchronously with step S17, the steering system inputs the left and right target turning angle signals of the controlled steering axle into the controller; Step S19: setting the switch status of the two parallel ball valves; Step S20: setting the emergency servo proportional valve to the left position or the right position; Step S21: The servo motor changes the motor speed through the voltage control signal to adjust the output flow and pressure of the quantitative pump; the electromagnetic reversing valve is controlled by using the angular velocity feedforward angle feedback control, and the left turn is set as positive. The deviation angle between the target angle and the actual angle of the left steering wheel is used as the feedback signal, the target angular velocity is used as the feedforward signal, and the sum of the feedback signal and the feedforward signal is used as the control signal. The control signal function is as follows: U=(θq-θs)+ωq Among them, U is the control signal, θq is the target angle, θs is the actual angle, and ωq is the target angular velocity.

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