Drive-by-wire hydraulic steering system and redundancy control method thereof

Abstract

The invention relates to a hydraulic steering-by-wire system and a redundancy control method thereof. The hydraulic steering-by-wire system comprises a double-controller terminal, a hydraulic steering system and a redundancy control system, the steering wheel subsystem comprises a steering wheel, a road sensing torque motor, a motor encoder, a torque motor driver and a steering encoder; the hydraulic steering wheel system comprises an oil supply hydraulic element, an electro-hydraulic proportional reversing valve, a safety pressure stabilizing valve block, a double-steering oil cylinder and a double-stroke sensor. The subsystems have redundancy for resisting single-point failure, fault detection is achieved through mutual verification of data of multiple sensors, a finite-state machine and a state switching mechanism of the finite-state machine are designed, redundancy control of the steering system under various abnormal working conditions is achieved, and stable operation of the steering system and safety of engineering tasks are guaranteed. Compared with the prior art, the method is more suitable for hinged type hydraulic steering equipment, the reliability and safety of the steering system are guaranteed through redundancy design, meanwhile, the steering precision is improved by fully utilizing redundancy equipment, and the cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of steering systems for engineering machinery equipment, and relates to a wire-controlled hydraulic steering system and a redundant control method thereof. Background Art

[0002] The steering system of traditional articulated construction equipment uses hydraulic power for rotation. For example, wheel loaders and wheel excavators use full hydraulic reversing valves to control the telescopic movement of dual hydraulic cylinders, thereby driving the front and rear ends of the construction machinery to rotate relative to the hinge point. It has the characteristics of relatively low cost. However, it also has obvious disadvantages, such as laborious steering, low steering accuracy, and poor return accuracy.

[0003] The biggest difference between SBW and other power steering systems is that there is no physical connection between the steering wheel and the actuator, which has obvious advantages in terms of control flexibility, functional richness, space layout, and reduced fuel consumption. The application of SBW in construction machinery is a general trend of development, which can realize advanced functions such as intelligent stable steering, variable transmission ratio and automatic driving of engineering equipment.

[0004] When working in harsh environments, construction machinery such as wheel loaders may encounter scenarios such as sensor damage and controller failure. Designing redundant systems and control strategies to improve the fault tolerance of the steering system is a core requirement for upgrading wire-controlled steering. The redundant design of the engineering construction steering system ensures normal operation when components are damaged, and rapid switching when a fault occurs, maintaining the continuity and safety of the project.

[0005] For example, CN202411005476.4 provides a wire-controlled steering device and control method with full redundancy function. The main design concept is that the wire-controlled steering device with full redundancy function obtains redundant four-way torque signals and two-way angle signals through the torque angle sensor on the steering wheel, and obtains redundant two-way angle signals from the angle sensor on the gear shaft to obtain accurate torque angle information; in addition, the road sense motor and the steering motor both use dual three-phase permanent magnet synchronous motors, and the road sense motor controller and the steering motor controller both use dual control unit architecture and redundant communication mechanism. Through the above three aspects of detailed redundant design, it is ensured that when a single point failure of the wire control occurs and three of the phases cannot work, the system still has road sense feedback and steering execution capabilities. Combined with the design of rack force and reference hand force calculation strategy in the control logic, the system can still maintain normal operation when the key components of the steering system fail, thereby ensuring the stability and safety of vehicle driving. This redundant solution cannot cope with the problem of single terminal controller signal failure, and the degree of redundancy is insufficient; and there is a complex mechanical transmission structure, high space occupancy rate, and high hardware cost of the redundant solution. There are no countermeasures for high-frequency and high-amplitude vibrations in complex construction environments, and the reduction in observation accuracy of multi-position sensors. There is a lack of redundant control measures to ensure accuracy, and it is unable to meet the needs of safe construction. Summary of the invention

[0006] The purpose of the present invention is to provide a wire-controlled hydraulic steering system and a redundant control method thereof, which effectively solves at least one of the problems of low matching accuracy of steering wheel angle and steering wheel angle of the hydraulic steering system of existing engineering construction equipment, laborious steering wheel operation, poor robustness, stability and safety of the steering system.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] In a first aspect, the present invention provides a wire-controlled hydraulic steering system, comprising:

[0009] A steering subsystem, comprising a steering wheel, a road-sensing torque motor, a motor encoder, a torque motor driver and a steering encoder, wherein the steering wheel is used to obtain the driver's steering intention, the road-sensing torque motor is connected to the steering wheel through a steering wheel transmission structure, the motor encoder and the steering encoder are used to simultaneously measure the steering angle of the steering wheel, and the torque motor driver is used to control the operation of the road-sensing torque motor;

[0010] The hydraulic steering wheel system includes an oil supply hydraulic element, an electro-hydraulic proportional reversing valve, a safety pressure-stabilizing valve block, a dual steering oil cylinder and a dual stroke sensor, wherein the dual stroke sensor is used to obtain the stroke data of the left and right sides of the dual steering oil cylinder;

[0011] The dual-controller terminal includes a main controller ECU and a backup controller ECU, wherein the main controller ECU serves as a working controller to process steering instructions and control wire-controlled hydraulic steering in real time, and the backup controller ECU serves as a verification controller to supervise the implementation of instructions from the working controller.

[0012] Furthermore, the main controller ECU and the backup controller ECU have a communication function. When the main controller ECU is abnormal, the main / backup switch is performed, and the backup controller ECU2 is used as the working controller to maintain the normal operation of the hydraulic steering system.

[0013] In a second aspect, the present invention provides a control method for a wire-controlled hydraulic steering system, comprising the following steps:

[0014] S1, execute the initialization steering system link, check the system unit status, and align the steering wheel and the steering wheel angle;

[0015] S2. Enter the working mode loop, detect the state of the steering system, and realize real-time wire-controlled steering. The redundant control strategy of wire-controlled steering adopts a finite state machine. By monitoring the different operating states of the steering system, state switching events and transfer logic are formulated to ensure the reliability of the steering function of the engineering vehicle.

[0016] Furthermore, in S1, in the initialization steering system link, the system unit status is checked, and the working controller calculates the steering wheel hinge point angle based on the steering angle observation value of the dual-stroke sensor, and inputs it into the torque motor driver as the desired steering wheel angle, so that it controls the road-sensing torque motor to drive the steering wheel to return to the steering wheel alignment angle through the steering wheel transmission structure.

[0017] Furthermore, the steering wheel return result is verified by the steering encoder observation value. When the road sense torque motor cannot drive the steering wheel to return during the initialization phase, it directly switches to the steering wheel angle observation abnormal state, and uses the current steering wheel angle as the steering wheel alignment angle to limit the steering range and steering ratio.

[0018] Further, in S2, in the redundant control strategy finite state machine, the entire wire-controlled hydraulic steering system has a normal state and an abnormal state, wherein the abnormal state is at least one of the following states. Therefore, there may be seven situations after mutual combination:

[0019] The abnormal state of the working controller will be activated by the failure event of the main controller ECU;

[0020] The abnormal state of steering wheel angle observation will be activated by the event that the difference between dual encoder observations exceeds the threshold;

[0021] The abnormal state of steering wheel angle observation will be activated by the event that the difference between the left and right steering wheel angle observations exceeds the threshold.

[0022] Furthermore, the activation logic of the main controller ECU failure event is: when the backup controller ECU executes the detection program and checks the IO, communication link and program logic execution abnormalities of the main controller ECU, the backup controller ECU obtains the internal variables of the main controller ECU and switches to the working mode to take over the control, and isolates the main controller ECU at the same time;

[0023] The event of the observation difference of the dual encoders exceeding the threshold is activated as follows: the working controller ECU obtains the steering angle values ​​of the motor encoder and the steering encoder in a single working cycle, and determines whether to shield the motor encoder built into the road sense torque motor according to the difference between the two and the preset threshold, and instead uses the value collected by the steering encoder as the driver's expected steering angle, and outputs a road sense torque motor failure warning message;

[0024] The event of the left and right steering wheel angle observation difference exceeding the threshold is activated: the steering wheel angle difference calculated from the dual stroke sensor observation values ​​is compared with the threshold. When it exceeds the threshold, it is determined that there is a failure, and the expected angle issued by the working ECU is used as a reference. The object with the largest angle deviation is regarded as the failed stroke sensor, and its collected values ​​are ignored and a warning message is output.

[0025] Furthermore, in the state detection of the steering system by S2, a redundant design is adopted for the state observation of the hydraulic steering wheel system, and redundant observation and precise measurement of the steering angle of the front end of the construction equipment are achieved with the help of the dual-stroke sensor installed on the dual steering cylinder;

[0026] The dual stroke sensors ensure that when one side of the stroke sensors fails, the steering angle can still be obtained by relying on the measurement result of the other side of the stroke sensor, thereby realizing redundant observation of the steering state.

[0027] Under normal working conditions, the dual stroke sensors simultaneously output the stroke data of the left and right sides of the dual steering cylinders. The derivation formula of the steering angle θ is:

[0028] θ=(θ l +θ r ) / 2,

[0029] Among them, the steering angle θ is derived based on the left travel data observed by the dual travel sensor l The calculation formula is:

[0030]

[0031] The steering angle θ is derived based on the right side travel angle observed by the dual travel sensor. r The calculation process is:

[0032]

[0033] Where, ΔL l Indicates the extension of the left side of the dual travel sensor relative to the straight line when driving in a straight line; ΔL r Indicates the extension of the right side of the dual travel sensor relative to the straight line when driving in a straight line; A, B, k, is a constant coefficient, and the calculation formula is:

[0034]

[0035] In the formula, h f Indicates the vertical distance from the front and rear hinge points to the front cylinder connection point, h r Indicates the vertical distance from the front and rear hinge points to the rear cylinder connection line, d f Indicates half of the distance to the front cylinder connection point, d r Indicates half of the distance to the rear cylinder connection point, h f 、h r d f d r It is measured when the vehicle is calibrated while driving in a straight line. It should be noted here that the articulated engineering machinery is divided into a front frame and a rear frame, and the articulated shaft is connected in the middle, which is common knowledge in the art.

[0036] Under abnormal conditions, the observation data provided by the normally operating single-stroke sensor is used as the steering angle value.

[0037] Furthermore, in S2, the steering system status is detected, and the steering wheel subsystem steering signal collection is redundantly designed. The steering wheel rotation angle is measured simultaneously by the motor encoder and the steering encoder. When the difference between the steering wheel angle observation values ​​of the two exceeds the threshold, it indicates that the encoder has failed, and the angle estimated by the cylinder stroke sensor is used as a reference, and the encoder with the largest angle deviation is judged to be failed.

[0038] When the motor encoder fails, making it impossible for the road-sensing torque motor to provide torque feedback, it is immediately isolated by the working controller and directly obtains the steering angle value of the steering encoder. The flow opening of the electro-hydraulic proportional reversing valve is then calculated from the difference between the steering wheel angle and the steering wheel angle, while limiting the maximum steering angle and steering speed.

[0039] When the steering encoder fails, it is also isolated by the system, and the steering wheel retains road feedback and transmits steering information normally. This allows mutual verification between sensors, which can not only detect failed components but also ensure accuracy.

[0040] Furthermore, S2 detects the state of the steering system in each working cycle. If a single or combined failure condition occurs in the main controller ECU, the travel sensor or the steering wheel angle measurement encoder, the finite state machine system can automatically switch to the corresponding state, execute the response action program, and maintain stable operation of the steering work.

[0041] Among them, the response action program for the failure of the main controller ECU is to enable the backup controller ECU and execute the working control program to obtain the operating status parameters of the main ECU; the response action program for the failure of a single steering wheel encoder is to use another single steering wheel encoder to read the steering intention; the response action program for the failure of a single stroke sensor is to use another single stroke sensor to observe the real-time turning angle. For comprehensive failure conditions, the state machine of the above combined response actions is used. Here, the motor encoder and the steering encoder are collectively referred to as the steering wheel encoder.

[0042] In a third aspect, the present invention provides a computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the steps of the control method of the wire-controlled hydraulic steering system as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A schematic diagram of a hydraulic steering-by-wire system for engineering machinery according to this embodiment;

[0044] Figure 2 This is a schematic diagram of a hydraulic articulated steering model of this embodiment;

[0045] Figure 3 Schematic diagram of program elements and state machine of the wire-controlled hydraulic steering system of this embodiment;

[0046] Figure 4 It is a program operation logic diagram of the redundant control strategy of the wire-controlled hydraulic steering system of this embodiment;

[0047] Description of the markings in the figure:

[0048] 1-steering wheel subsystem; 11-steering wheel; 12-steering wheel transmission structure; 13-road sense torque motor; 14-motor encoder; 15-torque motor driver; 16-steering encoder; 2-hydraulic steering wheel system, 21-oil supply hydraulic element; 22-electro-hydraulic proportional reversing valve; 23-safety pressure-stabilizing valve block; 24-dual steering cylinder; 25-dual stroke sensor; 31-main controller ECU; 32-backup controller ECU; 41-normal state; 42-abnormal state; 43-working controller abnormal state; 44-steering wheel angle observation abnormal state; 45-steering wheel angle observation abnormal state. DETAILED DESCRIPTION

[0049] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0050] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0051] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] In order to solve the problems of low matching accuracy between the steering wheel angle and the steering wheel 11 angle of the hydraulic steering system of the existing construction equipment, the difficulty in operating the steering wheel 11, and the poor robustness, stability and safety of the steering system, in some embodiments, a wire-controlled hydraulic steering system is provided, see Figure 1 As shown, it includes a steering wheel subsystem 1, a hydraulic steering wheel subsystem 22 and a controller terminal. The wire-controlled hydraulic steering system can achieve physical decoupling of the steering wheel 11 and the hydraulic steering wheel.

[0053] Please see again Figure 1 and Figure 2 As shown, in some specific embodiments, the steering subsystem 1 includes a steering wheel 11, a road-sensing torque motor 13, a motor encoder 14, a torque motor driver 15 and a steering encoder 16, wherein the steering wheel 11 is used to obtain the driver's steering intention, the road-sensing torque motor 13 is connected to the steering wheel 11 through a steering wheel transmission structure 12, the motor encoder 14 and the steering encoder 16 are used to simultaneously measure the steering angle of the steering wheel 11, and the torque motor driver 15 is used to control the operation of the road-sensing torque motor 13;

[0054] The hydraulic steering wheel system 2 includes an oil supply hydraulic element 21, an electro-hydraulic proportional reversing valve 22, a safety pressure-stabilizing valve block 23, a dual steering cylinder 24 and a dual stroke sensor 25, wherein the dual stroke sensor 25 is used to obtain the stroke data of the left and right sides of the dual steering cylinder 24;

[0055] The dual-controller terminal includes a main controller ECU 31 and a backup controller ECU 32, wherein the main controller ECU 31 serves as a working controller to process steering instructions and control wire-controlled hydraulic steering in real time, and the backup controller ECU 32 serves as a verification controller to supervise the implementation of instructions from the working controller.

[0056] The above-mentioned wire-controlled hydraulic steering system has three redundant designs, including the main / backup controller ECU redundant design, the steering subsystem 1 steering signal collection redundant design and the hydraulic steering wheel system 2 state observation redundant design, so as to ensure the reliability and stability of the wire-controlled hydraulic steering function and realize safe operation in engineering construction.

[0057] The main / backup controller ECU redundant design is that under normal working conditions, the main controller ECU 31 acts as the working controller to process steering instructions and control the steering system in real time; the backup controller ECU 32 acts as a verification controller to supervise the implementation of the instructions of the working controller. When the main controller ECU 31 is abnormal, the main / backup switch is performed, and the backup controller ECU 32 acts as the working controller to maintain the normal operation of the hydraulic steering system.

[0058] In some specific embodiments, the program function of the working controller is to perform closed-loop control on the steering of the articulated hydraulic steering mechanism based on the desired steering angle output by the steering subsystem 1 as input and the cylinder stroke collected by the dual-stroke sensor 25 as feedback information, so as to achieve labor-saving and precise steering. The main steering control program is equipped with functions such as custom steering ratio, steering road feel feedback and automatic return of the steering wheel 11 of the wire-controlled hydraulic steering system.

[0059] In some specific embodiments, Figure 3 As shown, the steering signal collection redundant design of the steering wheel subsystem 1 is characterized in that the motor encoder 14 of the road sense torque motor 13 and the additional absolute value steering encoder 16 are used to simultaneously measure the rotation angle of the steering wheel 11. When the difference between the two observed values ​​of the steering wheel 11 exceeds a threshold, it indicates that there is an encoder failure.

[0060] When the motor encoder 14 fails (no signal output), and the road sense torque motor 13 cannot provide torque feedback, it will be immediately isolated by the working controller ECU, and the system will be switched to the preparatory angle control program. The system directly obtains the steering angle value of the steering encoder 16, and calculates the flow opening of the electro-hydraulic proportional reversing valve 22 by the difference between the steering wheel 11 angle and the steering wheel angle observation. The steering program limits the maximum steering angle and steering speed at the same time. Although the road sense is lost, the driver can still control the steering of the vehicle. When the steering encoder 16 fails, it is also soft-isolated by the system, and the steering wheel 11 retains the road sense feedback and transmits steering information normally. The steering wheel 11 encoder failure inference result needs to be fed back to the user through the alarm system to facilitate timely maintenance.

[0061] In some specific embodiments, the redundant design of the state observation of the hydraulic steering wheel system 2 realizes redundant observation and accurate measurement of the steering angle of the front end of the construction equipment by means of the dual stroke sensors 25 installed on the dual steering cylinders 24. This design can ensure that when a single-side stroke sensor fails, the steering angle can still be obtained by relying on the measurement results of the remaining stroke sensors, thereby ultimately realizing redundant observation of the steering state.

[0062] like Figure 2 As shown, the dual-stroke sensor 25 is divided into a left stroke sensor and a right stroke sensor, which correspond to the left and right sides of the dual-stroke sensor 25 respectively. By acquiring the left stroke sensor data, the steering angle θ l The derivation formula is as follows:

[0063]

[0064] Where, ΔL l Indicates the extension of the left travel sensor when driving in a straight line relative to that when driving in a straight line. A, B, k, are four constant coefficients, and their calculation formula is as follows:

[0065]

[0066] Among them, h f Indicates the vertical distance from the front and rear hinge points to the front cylinder connection point, h r Indicates the vertical distance from the front and rear hinge points to the rear cylinder connection point, d f Indicates half of the distance to the front cylinder connection point, d r Indicates half of the distance to the rear cylinder connection point, h f 、h r d f d r Measured when the vehicle is calibrated while driving in a straight line.

[0067] Under normal working conditions, the dual stroke sensors 25 simultaneously output data to improve the measurement accuracy of the steering angle. After obtaining the stroke data of the left and right dual cylinders, the steering angle derivation formula is as follows:

[0068] θ=(θ l +θ r ) / 2

[0069] The right stroke sensor 25 observes the estimated steering angle result θ r The calculation process is as follows:

[0070]

[0071] ΔL r Indicates the extension of the right travel sensor when driving in a straight line relative to that when driving in a straight line. is the constant coefficient on the right side.

[0072] Under abnormal conditions, the observation data provided by the normally operating single-stroke sensor is used as the steering angle value.

[0073] Based on the above-provided wire-controlled hydraulic steering system, in some embodiments, a control method of the wire-controlled hydraulic steering system is further provided, specifically:

[0074] After the hydraulic steering control system is started, it first executes the initialization steering system program to align the steering wheel 11 with the steering wheel angle, enters the working mode cycle, and then performs steering device status detection to achieve real-time wire control steering. Among them, the redundant control strategy of wire control steering adopts a finite state machine, which monitors the different operating states of the steering system, formulates state switching events and transfer logic, and ensures the reliability of the steering function of the engineering vehicle.

[0075] In some specific embodiments, in the initialization steering system link, the working controller ECU calculates the steering wheel hinge angle according to the steering angle observation value of the dual-stroke sensor 25, and inputs it into the torque motor driver 15 as the desired steering angle of the steering wheel 11, so that it controls the road-sensing torque motor 13 to drive the steering wheel 11 to return to the steering wheel alignment angle through the steering wheel transmission structure 12. The steering wheel 11 return result is verified by the steering encoder 16 observation value. When the road-sensing torque motor 13 cannot drive the steering wheel 11 to return in the initialization link, it directly switches to the steering wheel angle observation abnormal state, and uses the current steering wheel 11 angle as the steering wheel alignment angle, and limits the steering range and steering ratio.

[0076] In the redundant control strategy finite state machine, the entire hydraulic steering system has 8 states (including normal state 41 and abnormal state 42), and the working controller ECU is used as the logic calculation unit for state switching:

[0077] Among them, when in the normal state 41, the built-in motor encoder 14 of the road sense torque motor 13 is used as the acquisition sensor of the reverse disk angle, and the steering encoder 16 is responsible for verifying the steering angle acquisition situation; the main controller ECU 31 is used as the working controller, and the backup controller ECU 32 is used as the verification controller to monitor the execution status of the working controller instructions and prepare to replace the main controller ECU 31; the left and right double-stroke sensors 25 simultaneously observe the angles of the front and rear end hinge points.

[0078] The abnormal state 42 includes three basic situations and their combination modes. The three basic situations are respectively a working controller abnormal state 43, a steering wheel angle observation abnormal state 44, and a steering wheel angle observation abnormal state 45. Therefore, there are 7 abnormal states.

[0079] The abnormal state of the working controller will be activated by the failure event of the main controller ECU, and the event activation logic is as follows: when the backup controller ECU 32 executes the detection program and checks the IO, communication link and program logic execution abnormalities of the main controller ECU 31, the backup controller ECU 32 obtains the internal variables of the main controller ECU 31 and switches to the working mode to take over control, while isolating the main controller ECU 31.

[0080] The abnormal state of steering wheel angle observation will be activated by the event of the difference between the dual encoder observations exceeding the threshold. The event activation logic is as follows: the working controller ECU obtains the steering angle value of the dual encoders in a single working cycle, and determines whether to shield the built-in encoder of the road sense torque motor 13 based on the difference between the two and the preset threshold, and instead uses the value collected by the steering encoder 16 as the driver's expected steering angle, and outputs a torque motor failure warning message.

[0081] The abnormal state of steering wheel angle observation will be activated by the event that the difference between the left and right steering wheel angle observations exceeds the threshold. The event activation logic is as follows: the difference between the steering wheel angles calculated from the observation values ​​of the dual travel sensors 25 is compared with the threshold. When it exceeds the threshold, it is determined that there is a failure, and based on the expected angle in the current working cycle, the failed travel sensor is determined, its collected value is ignored, and a warning message is output.

[0082] In some specific embodiments, during the control operation, the main / backup controller adopts a redundant design, the working controller ECU is responsible for real-time control of the operation of the wire-controlled steering system, and the backup controller ECU 32 monitors the execution effect of the main controller in real time, and the two controllers have communication. When the main controller ECU 31 fails, the backup controller ECU 32 can immediately receive the intermediate variable data sent by the main controller ECU 31, and switch to the working mode to run the steering control program to ensure the continuous operation of the wire-controlled steering system. The dual closed-loop control circuit adopted by the present invention solves the problem of a single controller failing to steer, and improves the safety and stability of the system.

[0083] In some specific embodiments, the state of the steering system is detected during a certain working cycle, and a single or combined failure condition of the main controller ECU31, the travel sensor or the steering wheel angle measurement encoder occurs. The finite state machine system can automatically switch to the corresponding state, execute the response action program, and maintain stable operation of the steering work.

[0084] The response action program for the failure of the main controller ECU is to enable the backup controller ECU 32 and execute the working control program to obtain the operating status parameters of the main ECU; the response action program for the failure of a single steering wheel encoder is to use another single steering wheel encoder to read the steering intention; the response action program for the failure of a single stroke sensor 25 is to use another single stroke sensor to observe the real-time steering angle. For comprehensive failure conditions, the state machine of the above combined response actions is used.

[0085] In addition, in some embodiments, a computer readable storage medium is provided, which stores a computer program, and when the computer program is executed by a processor, the steps of the control method of the wire-controlled hydraulic steering system as described above are implemented. The storage medium can be an electronic medium, a magnetic medium, an optical medium, an electromagnetic medium, an infrared medium, or a semiconductor system or a propagation medium. The storage medium can also include semiconductor or solid-state memory, a magnetic tape, a removable computer disk, a random access memory (RAM), a read-only memory (ROM), a hard disk, and an optical disk. The optical disk can include a compact disk-read only memory (CD-ROM), a compact disk-read / write (CD-RW), and a DVD.

[0086] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A wire-controlled hydraulic steering system, characterized in that: include: A steering subsystem, comprising a steering wheel, a road-sensing torque motor, a motor encoder, a torque motor driver and a steering encoder, wherein the steering wheel is used to obtain the driver's steering intention, the road-sensing torque motor is connected to the steering wheel through a steering wheel transmission structure, the motor encoder and the steering encoder are used to simultaneously measure the steering angle of the steering wheel, and the torque motor driver is used to control the operation of the road-sensing torque motor; The hydraulic steering wheel system includes an oil supply hydraulic element, an electro-hydraulic proportional reversing valve, a safety pressure-stabilizing valve block, a dual steering oil cylinder and a dual stroke sensor, wherein the dual stroke sensor is used to obtain the stroke data of the left and right sides of the dual steering oil cylinder; The dual-controller terminal includes a main controller ECU and a backup controller ECU, wherein the main controller ECU serves as a working controller to process steering instructions and control wire-controlled hydraulic steering in real time, and the backup controller ECU serves as a verification controller to supervise the implementation of instructions from the working controller.

2. A wire-controlled hydraulic steering system according to claim 1, characterized in that: There is a communication function between the main controller ECU and the backup controller ECU. When the main controller ECU is normal, it acts as a working controller and the backup controller ECU acts as a verification controller. When the main controller ECU is abnormal, the main / backup switching is performed and the backup controller ECU acts as the working controller to maintain the normal operation of the hydraulic steering system.

3. A control method for a wire-controlled hydraulic steering system according to claim 1 or 2, characterized in that: The following steps are involved: S1, execute the initialization steering system link, check the system unit status, and align the steering wheel and the steering wheel angle; S2. Enter the working mode loop, detect the state of the steering system, and realize real-time wire-controlled steering. The redundant control strategy of wire-controlled steering adopts a finite state machine. By monitoring the different operating states of the steering system, state switching events and transfer logic are formulated to ensure the reliability of the steering function of the engineering vehicle.

4. The control method of a wire-controlled hydraulic steering system according to claim 3, characterized in that: In S1, in the initialization steering system link, the working controller collects and verifies the status of each unit, calculates the front and rear end hinge angles based on the steering angle observation values ​​of the dual-stroke sensor, and inputs it into the torque motor driver as the desired steering wheel angle, so that it controls the road-sensing torque motor to drive the steering wheel to return to the steering wheel alignment angle through the steering wheel transmission structure.

5. The control method of a wire-controlled hydraulic steering system according to claim 4, characterized in that: The steering wheel return result is verified by the steering encoder observation value. When the road sense torque motor cannot drive the steering wheel to return during the initialization phase, it directly switches to the steering wheel angle observation abnormal state, and uses the current steering wheel angle as the steering wheel alignment angle to limit the steering range and steering ratio.

6. The control method of a wire-controlled hydraulic steering system according to claim 3, characterized in that: In S2, in the redundant control strategy finite state machine, the entire wire-controlled hydraulic steering system has a normal state and an abnormal state, wherein the abnormal state is at least one of the following states: The abnormal state of the working controller will be activated by the failure event of the main controller ECU; The abnormal state of steering wheel angle observation will be activated by the event that the difference between dual encoder observations exceeds the threshold; The abnormal state of steering wheel angle observation will be activated by the event that the difference between the left and right steering wheel angle observations exceeds the threshold.

7. The control method of a wire-controlled hydraulic steering system according to claim 6, characterized in that: The activation logic of the main controller ECU failure event is: when the backup controller ECU executes the detection program and checks the IO, communication link and program logic execution of the main controller ECU, the backup controller ECU obtains the internal variables of the main controller ECU and switches to the working mode to take over the control, and isolates the main controller ECU at the same time; The activation logic of the dual encoder observation difference exceeding the threshold event is as follows: the working controller ECU obtains the steering angle values ​​of the motor encoder and the steering encoder in a single working cycle, and determines whether to shield the motor encoder built into the road sense torque motor based on the difference between the two and the preset threshold, and instead uses the value collected by the steering encoder as the driver's expected steering angle, and outputs a road sense torque motor failure warning message; The activation logic of the event when the difference in the observed left and right steering wheel angles exceeds the threshold is as follows: the difference in the steering wheel angles calculated from the dual-stroke sensor observations is compared with the threshold. When it exceeds the threshold, it is determined that there is a failure. The expected steering angle issued by the working controller is used as a reference, and the object with the largest angle deviation is regarded as the failed stroke sensor. Its collected values ​​are ignored and a warning message is output.

8. The control method of a wire-controlled hydraulic steering system according to claim 3, characterized in that: In the S2 steering system status detection, redundant design is adopted for the status observation of the hydraulic steering wheel system, and redundant observation and accurate measurement of the steering angle of the front end of the construction equipment are achieved with the help of the dual-stroke sensor installed on the dual steering cylinder; The dual stroke sensors ensure that when one side of the stroke sensors fails, the steering angle can still be obtained by relying on the measurement result of the other side of the stroke sensor, thereby realizing redundant observation of the steering state; Under normal working conditions, the dual stroke sensors simultaneously output the stroke data of the left and right sides of the dual steering cylinders. The derivation formula of the steering angle θ is: θ=(θ l +θ r ) / 2, Among them, the steering angle θ is derived based on the left travel data observed by the dual travel sensor l The calculation formula is: The steering angle θ is derived based on the right side travel angle observed by the dual travel sensor. r The calculation process is: Where, ΔL l Indicates the extension of the left side of the dual travel sensor relative to the straight-line driving; ΔL r Indicates the extension of the right side of the dual travel sensor relative to the straight line when driving in a straight line; A, B, k, is a constant coefficient, and the calculation formula is: In the formula, h f Indicates the vertical distance from the front and rear hinge points to the front cylinder connection point, h r Indicates the vertical distance from the front and rear hinge points to the rear cylinder connection point, d f Indicates half of the distance to the front cylinder connection point, d r Indicates half of the distance to the rear cylinder connection point, h f 、h r ,d f ,d r Measured when the vehicle is calibrated while driving in a straight line; Under abnormal conditions, the observation data provided by the normally operating single-stroke sensor is used as the steering angle value.

9. The control method of a wire-controlled hydraulic steering system according to claim 3, characterized in that: In S2, the steering system status is detected. The steering signal collection of the steering wheel subsystem is redundantly designed. The steering wheel rotation angle is measured simultaneously by the motor encoder and the steering encoder. When the difference between the steering wheel angle observation values ​​of the two exceeds the threshold, it indicates that the encoder has failed. The angle estimated by the cylinder stroke sensor is used as a reference, and the encoder with the largest angle deviation is judged to be failed. When the motor encoder fails, making it impossible for the road-sensing torque motor to provide torque feedback, it is immediately isolated by the working controller and directly obtains the steering angle value of the steering encoder. The flow opening of the electro-hydraulic proportional reversing valve is then calculated from the difference between the steering wheel angle and the steering wheel angle, while limiting the maximum steering angle and steering speed. When the steering encoder fails, it is also isolated by the system, and the steering wheel retains road feel feedback and transmits steering information normally.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the control method of the wire-controlled hydraulic steering system as claimed in claim 3 are implemented.

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