A steering system safety protection method and device for a three-axle all-wheel steering vehicle

Abstract

The present disclosure provides a steering system safety protection method and device for a three-axle all-wheel steering vehicle. The target steering mode and the target turning angle percentage of the designated axis are sent to the steering system through the self-driving control system of the steering vehicle; the absolute value of the difference between the target turning angle percentage and the actual turning angle percentage of the designated axis is calculated. If it is greater than the first difference threshold, timing is performed. When the accumulated timing time exceeds the first time threshold, a fault is reported; if it is less than the first difference threshold, the timing is reset; the absolute value of the difference between the actual turning angle percentages of the left and right wheels in each axis is calculated. If it is greater than the second difference threshold, timing is performed. When the accumulated timing time exceeds the second time threshold, a fault is reported; if it is less than the second difference threshold, the timing is reset; one of the four steps is selected for execution according to the actual steering mode. Through calculations under different steering modes, steering faults can be effectively diagnosed to ensure safe steering of multi-axle vehicles.

Description

Background Art

[0002] All-Wheel Drive (AWD) vehicles usually refer to vehicles with more than two axles and all wheels of multiple axles can participate in steering. All-Wheel Drive vehicles have a series of advantages over traditional two-wheel drive vehicles, especially in the application of autonomous driving scenarios in some unmanned ports. In order to cope with the complex port environment and port space, its advantages in maneuverability and handling performance can greatly improve the steering ability of the vehicle.

[0003] like Figure 1 As shown, the all-wheel steering vehicle targeted by the present invention has three axles, which are respectively located at the front, the middle and the rear of the vehicle. Different steering modes suitable for the vehicle can be selected for selection in different application scenarios and working conditions.

[0004] However, due to the large number of axles and wheels, and the many steering modes of three-axle vehicles, on the one hand, for unmanned vehicles with older hydraulic steering systems, insufficient oil pressure in the steering system may cause the actual wheel angle to not turn as commanded, which poses a great risk when turning; on the other hand, for some car manufacturers with immature steering systems (in the prototype development and debugging stage) or unstable steering system control technology, if the steering of a designated axle or designated tire fails but is not diagnosed in time, there will also be greater risks when turning.

[0005] However, in the prior art, no effective safety protection method has been proposed for the steering system of a three-axle all-wheel vehicle during driving, so as to ensure the driving safety of the three-axle steering system during operation. Summary of the invention

[0006] The purpose of the present disclosure is to provide a steering system safety protection method and device for a three-axle all-wheel steering vehicle, which can effectively diagnose various steering modes of the three-axle vehicle during driving, so as to achieve safe steering and timely maintenance when problems occur.

[0007] Other features and advantages of the present disclosure will become apparent from the following detailed description, or may be learned in part by the practice of the present disclosure.

[0008] According to one aspect of the present disclosure, a steering system safety protection method for a three-axle all-wheel steering vehicle includes:

[0009] Its three-axle all-wheel steering vehicle includes a first axle located at the front of the vehicle, a second axle located at the center of the vehicle and a third axle located at the rear of the vehicle;

[0010] The target steering mode and the target turning angle percentage of the specified axis are sent to the steering system through the self-driving control system of the steering vehicle;

[0011] The absolute value of the difference between the target angle percentage and the actual angle percentage of the specified axis is calculated in real time. If it is greater than the first difference threshold, timing is performed. When the accumulated timing time exceeds the first time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running. If it is less than the first difference threshold, the timing is reset to zero and the vehicle resumes normal operation.

[0012] The absolute value of the difference between the actual turning angle percentages of the left wheel and the right wheel of each axis is calculated in real time respectively. If it is greater than the second difference threshold, timing is performed. When the accumulated timing time exceeds the second time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running; if it is less than the second difference threshold, the timing is reset to zero and the vehicle resumes normal operation;

[0013] Select one of the following four steps to execute according to the actual steering mode:

[0014] When the actual steering mode is the front-wheel steering mode, the larger value of the absolute value of the actual turning angle percentage of the left wheel and the right wheel of the third axle is first taken. If it is greater than the first turning angle threshold, timing is performed. When the accumulated timing time exceeds the third time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running; if it is less than the first turning angle threshold, the timing is reset, and the absolute value of the difference between the actual turning angle percentages of the two tires on either side of the first axle and the second axle is further calculated. If it is greater than the third difference threshold, timing is performed. When the accumulated timing time exceeds the third time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running. If it is less than the third difference threshold, the timing is reset, and the vehicle resumes normal operation.

[0015] When the actual steering mode is the rear-wheel steering mode, the larger value of the absolute value of the actual turning angle percentage of the left wheel and the right wheel of the first axle is first taken. If it is greater than the first turning angle threshold, timing is performed. When the accumulated timing time exceeds the third time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running; if it is less than the first turning angle threshold, the timing is reset, and the absolute value of the difference between the actual turning angle percentages of the two tires on either side of the second axle and the third axle is further calculated. If it is greater than the third difference threshold, timing is performed. When the accumulated timing time exceeds the third time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running. If it is less than the third difference threshold, the timing is reset, and the vehicle resumes normal operation.

[0016] When the actual steering mode is the large-angle steering mode, the larger value of the absolute value of the actual turning angle percentage of the left wheel and the right wheel of the second axle is first taken. If it is greater than the first turning angle threshold, timing is performed. When the cumulative timing time exceeds the first time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running; if it is less than the first turning angle threshold, the timing is reset, and the addition value between the actual turning angle percentages of the two tires on either side of the first axle and the third axle is further calculated. If it is greater than the first addition threshold or less than the negative first addition threshold, timing is performed. When the cumulative timing time exceeds the third time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running. If it is less than the first addition threshold or greater than the negative first addition threshold, the timing is reset, and the vehicle resumes normal operation.

[0017] When the actual steering mode is the lane change steering mode, take any two groups of the first axis and the second axis or the second axis and the third axis or the first axis and the third axis, and calculate the absolute value of the difference between the actual turning angle percentages of the two tires on the same side in each group, and take the larger of the two absolute values. If the larger value is greater than the fourth difference threshold, timing is performed. When the accumulated timing time exceeds the first time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running; if it is less than the fourth difference threshold, the timing is reset and the vehicle resumes normal operation.

[0018] As further improvements, include:

[0019] When the current speed of the vehicle is less than the first speed threshold, the self-driving system determines that the vehicle is stationary and performs the following steps:

[0020] Get the actual steering percentage of the specified axis in real time. If it is greater than zero, set the actual steering percentage to the first maximum steering percentage limit value, and set zero to the first minimum steering percentage limit value; if it is less than zero, set the actual steering percentage to the first minimum steering percentage limit value, and set zero to the first maximum steering percentage limit value;

[0021] Obtain the current load of the vehicle in real time, and set the corresponding second maximum steering percentage limit value according to different loads;

[0022] The smaller value between the first minimum steering percentage limit value and the negative second maximum steering percentage limit value is taken as the minimum target value, and the larger value between the first maximum steering percentage limit value and the second maximum steering percentage limit value is taken as the maximum target value. The range of the target steering percentage of the steering system is limited to between the minimum target value and the maximum target value.

[0023] As further improvements, include:

[0024] Before the self-driving system switches steering mode, perform the following steps:

[0025] S1: limit the current speed of the vehicle to zero;

[0026] S2: When the current actual speed of the vehicle is less than the second speed threshold, the self-driving system determines that the vehicle is about to stop, and at this time limits the target turning angle percentage of the designated axis to zero, so as to control the wheel of the designated axis to return to the center before the vehicle stops;

[0027] S3: When the current speed of the vehicle is less than the first speed threshold and the absolute value of the actual steering percentage is less than the second turning angle threshold, the self-driving system sends a target steering mode to the steering system;

[0028] S4: When the actual steering mode is switched to the target steering mode, the self-driving system removes restrictions on the vehicle speed and target turning angle percentage.

[0029] As further improvements, include:

[0030] When the absolute value of the difference between the target angle percentage and the actual angle percentage of the specified axis is calculated in real time, further judgment is made. If it is greater than the fifth difference threshold, timing is performed. When the accumulated timing time exceeds the second time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running; if it is less than the fifth difference threshold, the timing is reset to zero and the vehicle resumes normal operation;

[0031] The fifth difference threshold is at least 1.5 times the first difference threshold, and the first time threshold is at least 1.5 times the second time threshold.

[0032] As a further improvement, when the current load of the vehicle is obtained in real time and the corresponding second maximum steering percentage limit value is set according to different loads, it specifically includes:

[0033] When the vehicle load is greater than 20 tons and less than or equal to 40 tons, the second maximum steering percentage limit value is set to 60%;

[0034] When the vehicle load is greater than 40 tons and less than or equal to 60 tons, the second maximum steering percentage limit value is set to 40%;

[0035] When the vehicle load is greater than 60 tons, the second maximum steering percentage limit value is set to 20%.

[0036] As a further improvement, the range of the third difference threshold is 0-60%; the range of the fourth difference threshold is 0-17%; and the range of the second difference threshold is 0-17%.

[0037] As a further improvement, when the accumulated timing time exceeds the first time threshold, the fault reported is that there is a fault in the execution of the steering system;

[0038] When the accumulated timing time exceeds the second time threshold, the fault reported is that there is a fault in the execution of the left and right wheel angles of the specified axis;

[0039] When the steering mode is the front-wheel steering mode and the angle is greater than the first turning angle threshold, the reported fault is that the third axis has a turning angle;

[0040] When the steering mode is the front-wheel steering mode and the difference is greater than the third difference threshold, the fault reported is that the difference between the steering angles of the first axis and the second axis is too large;

[0041] When the steering mode is the rear-wheel steering mode and the angle is greater than the first turning angle threshold, the fault reported is that the first axis has a turning angle;

[0042] When the steering mode is the rear-wheel steering mode and the difference is greater than the third difference threshold, the fault reported is that the difference between the second axis and the second axis is too large;

[0043] When the steering mode is a large-angle steering mode and the angle is greater than the first turning angle threshold, the reported fault is that the second axis has a turning angle;

[0044] When the steering mode is a large-angle steering mode and is greater than the first addition threshold or less than the negative first addition threshold, the reported fault is that the steering angle directions between the first axis and the third axis are the same or the difference is too large;

[0045] When the steering mode is the lane change steering mode, the reported fault is that the steering angles of at least two specified axes are different.

[0046] A steering system safety protection device for a three-axle all-wheel steering vehicle, comprising:

[0047] A control module, used to send a target steering mode and a target angle percentage of a specified axis to the steering system;

[0048] The designated axis rotation angle judgment module is used to calculate the absolute value of the difference between the target rotation angle percentage and the actual rotation angle percentage of the designated axis in real time, and execute the corresponding instruction according to the result;

[0049] The coaxial left and right wheel judgment module is used to calculate the absolute value of the difference between the actual turning angle percentages of the left and right wheels in each axis in real time, and execute corresponding instructions according to the results;

[0050] The steering mode judgment module determines whether the vehicle's current actual steering module is in the front-wheel steering mode, the rear-wheel steering mode, the large-angle steering mode, or the lane-changing steering mode, and then calculates the specified axis angle of the current actual steering module, and executes the corresponding instructions based on the result.

[0051] An electronic device comprises: a processor; and a memory for storing executable instructions of the processor;

[0052] Wherein, the processor is configured to perform the security protection method by executing the executable instructions.

[0053] A computer-readable storage medium stores a computer program, which implements the security protection method when executed by a processor.

[0054] The embodiment of the present disclosure provides a steering system safety protection method for a three-axle all-wheel steering vehicle. First, in any steering mode, the absolute value of the difference between the target turning angle percentage and the actual turning angle percentage of each designated axle, as well as the absolute value of the difference between the actual turning angle percentage of the left wheel and the right wheel in each designated axle are calculated to determine the basic steering condition of the designated axle. Only when there is no fault in the basic steering condition, it is meaningful to determine the fault in the actual steering mode to avoid invalid judgment. Therefore, the previous two steps are particularly important. At the same time, there is no logical relationship between the sequence of the two judgment steps. If there is no fault based on these two steps, the fault judgment method corresponding to the mode is further selected according to the actual steering mode, so that fast and effective fault troubleshooting can be effectively performed for different steering modes, ensuring that the three-axle vehicle can ensure the normal operation of the steering system in real time in each steering mode, troubleshooting risks in advance, and avoiding safety risks caused by steering system failures during vehicle driving.

[0055] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0057] Figure 1 A schematic plan view of a three-axle vehicle in one embodiment of the present disclosure is shown;

[0058] Figure 2 A schematic plan view showing different steering modes of a three-axle vehicle in one embodiment of the present disclosure;

[0059] Figure 3 A schematic diagram showing a steering failure when a three-axle vehicle is in a lane change steering mode in one embodiment of the present disclosure is shown;

[0060] Figure 4 A structural block diagram of a computer device in one embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0061] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the disclosure will be more comprehensive and complete and to fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0062] In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0063] like Figure 2 As shown, the three-axle vehicle has the following steering modes:

[0064] 1. Front-wheel steering mode: When the vehicle is driving on a road section where it needs to go straight or turn at a small angle, it switches to front-wheel steering mode. At this time, the steering angles of the wheels of the first axle and the second axle have a certain coordinated steering relationship, that is, the wheels of the two axles rotate clockwise or counterclockwise, while the wheel axle of the third axle never turns, so as to achieve stable driving under this working condition.

[0065] 2. Rear-wheel steering mode: When the vehicle is driving in a direction that requires reversing or the planned driving route is behind the vehicle, it switches to rear-wheel steering mode. At this time, the steering angles of the wheels of the second and third axles have a certain coordinated steering relationship, that is, the wheels of the two axles rotate clockwise or counterclockwise, while the wheel axle of the first axle never turns, so as to achieve stable driving under this working condition.

[0066] 3. Lane change steering mode: When the vehicle is driving on a road section where lane change is required, it switches to lane change steering mode. At this time, the tires of the three axles of the vehicle are controlled to rotate in the same direction and at the same angle to shorten the straight-line distance required for lane change and the success rate of lane change in narrow environments;

[0067] 4. Large-angle steering mode: When you need to make some large-angle turns, switch to this mode. At this time, the wheels of the first and third axles of the vehicle are controlled to steer in opposite directions with the same angle change value. At this time, the second axle does not turn at all to improve the steering flexibility of the vehicle when making large-angle turns.

[0068] The solution provided in this application is a steering system safety protection method for a three-axle all-wheel steering vehicle, comprising:

[0069] Its three-axle all-wheel steering vehicle includes a first axle located at the front of the vehicle, a second axle located at the center of the vehicle and a third axle located at the rear of the vehicle;

[0070] The self-driving control system of the steering vehicle sends the target steering mode and the target angle percentage of the specified axis to the steering system. The specified axis can be a single axis or multiple axes; the target angle percentage is calculated by the self-driving control system through the degree of deviation of the vehicle from the self-driving route, and the actual angle is the actual angle of the executing wheel fed back by the steering system (obtained according to the angle sensor). Generally, the steering system will control the angle of a certain wheel to the target angle percentage issued by the self-driving control system, and then automatically control the angles of the remaining wheels according to the steering mode. For example, in the front wheel, large angle steering, and lane change modes, the left front wheel first executes the target angle percentage request of the self-driving control system, and in the rear wheel mode, the right rear wheel first executes the target angle percentage request of the self-driving control system. The control of the steering system belongs to the existing technology and will not be elaborated here.

[0071] The absolute value of the difference between the target turning angle percentage and the actual turning angle percentage of the designated axis is calculated in real time. If it is greater than the first difference threshold (which can be calibrated according to actual conditions. Since the maximum turning angle of a single tire of a three-axle vehicle is 30°, the angle difference between the target turning angle and the actual turning angle is within 5°, the first difference threshold is controlled within 17% according to the percentage conversion. The calculation logic of the following related thresholds is the same), timing is performed. When the accumulated timing time exceeds the first time threshold (which can be calibrated according to actual conditions, generally within 3s), a steering system execution fault is reported, and the vehicle speed is limited (such as calibrated to 5kph) or the vehicle is prohibited from running; if it is less than the first difference threshold, the timing is reset and the vehicle resumes normal operation; this is the single-axis situation described above, in which the turning angle of a certain wheel is controlled to the target turning angle percentage issued by the self-driving control system, and then the turning angles of the remaining wheels are automatically controlled according to the steering mode, so it is only necessary to judge the corresponding single designated axis.

[0072] The absolute value of the difference between the actual turning angle percentages of the left and right wheels of each axis is calculated in real time. If it is greater than the second difference threshold (which can be calibrated according to the actual situation, generally within 17%), timing is performed. When the accumulated timing time exceeds the second time threshold (which can be calibrated according to the actual situation, generally within 3s), a fault is reported in the execution of the left and right wheel turning angles of the specified axis, and the vehicle is speed-limited or prohibited from running; if it is less than the second difference threshold, the timing is reset and the vehicle resumes normal operation;

[0073] Select one of the following four steps to execute according to the actual steering mode:

[0074] When the actual steering mode is the front-wheel steering mode, the larger value of the absolute value of the actual turning angle percentage of the left and right wheels of the third axle is taken first. If it is greater than the first turning angle threshold (which can be calibrated according to the actual situation, generally within 17%), timing is performed. When the accumulated timing time exceeds the third time threshold (which can be calibrated according to the actual situation, generally within 3s), the third axle is reported to have a turning angle fault, and the vehicle is speed-limited or prohibited from running; if it is less than the first turning angle threshold, the timing is reset, and the actual two tires on either side of the first and second axles are further calculated. If the absolute value of the difference between the turning angle percentages is greater than the third difference threshold (since the maximum turning angle of a single tire of a three-axle vehicle is 30°, in the front-wheel steering mode, the turning angle of the first axle on the same side will be 18° more than the turning angle of the second axle at most, so according to the percentage conversion, the first difference threshold is controlled within 60%), timing is performed. When the accumulated timing time exceeds the third time threshold, a fault of excessive turning angle difference between the first axle and the second axle is reported, and the vehicle is speed-limited or prohibited from running. If it is less than the third difference threshold, the timing is reset to zero and the vehicle resumes normal operation.

[0075] When the actual steering mode is the rear-wheel steering mode, the larger value of the absolute value of the actual turning angle percentage of the left wheel and the right wheel of the first axle is first taken. If it is greater than the first turning angle threshold, timing is performed. When the accumulated timing time exceeds the third time threshold, it is reported that the first axle has a turning angle fault, and the vehicle is speed-limited or prohibited from running. If it is less than the first turning angle threshold, the timing is reset, and the absolute value of the difference between the actual turning angle percentages of the two tires on the same side of the second axle and the third axle is further calculated. If it is greater than the third difference threshold (because the maximum turning angle of a single tire of a three-axle vehicle is 30°, in the rear-wheel steering mode, the turning angle of the third axle on the same side will be 18° more than the turning angle of the second axle at most, so according to the percentage conversion, the first difference threshold is controlled within 60%), timing is performed. When the accumulated timing time exceeds the third time threshold, a fault of excessive turning angle difference between the second axle and the second axle is reported, and the vehicle is speed-limited or prohibited from running. If it is less than the third difference threshold, the timing is reset, and the vehicle resumes normal operation.

[0076] When the actual steering mode is the large-angle steering mode, the larger value of the absolute value of the actual turning angle percentage of the left wheel and the right wheel of the second axle is first taken. If it is greater than the first turning angle threshold, timing is performed. When the cumulative timing time exceeds the first time threshold, it is reported that the second axle has a turning angle fault, and the vehicle is speed-limited or prohibited from running; if it is less than the first turning angle threshold, the timing is reset, and the addition value between the actual turning angle percentages of the two tires on either side of the first axle and the third axle is further calculated. If it is greater than the first addition threshold (which can be calibrated according to actual conditions, generally within 17%) or less than the negative first addition threshold, timing is performed. When the cumulative timing time exceeds the third time threshold, it is reported that the turning angle directions between the first axle and the third axle are the same or the difference is too large, and the vehicle is speed-limited or prohibited from running. If it is less than the first addition threshold or greater than the negative first addition threshold, the timing is reset and the vehicle resumes normal operation.

[0077] When the actual steering mode is the lane change steering mode, take any two groups of the first axis and the second axis or the second axis and the third axis or the first axis and the third axis, and calculate the absolute value of the difference between the actual turning angle percentages of the two tires on the same side in each group, and take the larger of the two absolute values. If the larger value is greater than the fourth difference threshold (which can be calibrated according to actual conditions, generally within 17%), timing is performed. When the accumulated timing time exceeds the first time threshold, a fault of different turning angles of at least two specified axes is reported, and the vehicle is speed-limited or prohibited from running; if it is less than the fourth difference threshold, the timing is reset and the vehicle resumes normal operation.

[0078] The overall three-axle vehicle will first calculate the absolute value of the difference between the target angle percentage and the actual angle percentage of each designated axle in any steering mode, as well as the absolute value of the difference between the actual angle percentages of the left wheel and the right wheel in each designated axle, to determine the basic steering situation of the designated axle. Only when there is no fault in the basic steering situation, it is meaningful to determine the fault in the actual steering mode to avoid invalid judgment. Therefore, the previous two judgment steps are particularly important. At the same time, there is no logical relationship between the sequence of the two judgment steps. If there is no fault based on these two steps, the actual steering mode is further selected to select the fault judgment method corresponding to the mode, which can effectively perform fast and effective troubleshooting for different steering modes, ensuring that the three-axle vehicle can ensure the normal operation of the steering system in real time in each steering mode, and troubleshoot risks in advance to avoid safety risks caused by steering system failures during vehicle driving.

[0079] In this embodiment, since the steering system and the power control system of the vehicle work independently of each other, the problem of the wheels turning when the vehicle is stationary may occur in the following situations:

[0080] 1. When the vehicle is manually driven to the vicinity of the route (but not on the route) or manually driven to the turning route, and the wheels are manually straightened, the self-driving mode is switched to the automatic driving mode. The automatic driving system will calculate the direction and steer the wheel according to the degree of deviation between the vehicle and the route. However, there is an obstacle in front, so the power control system does not output power to prohibit the vehicle from driving, and the steering wheel will be steered when the vehicle is stationary.

[0081] 2. When the vehicle is driving, a new lane change or turning route is issued, but there is an obstacle on the new route that is close to the vehicle, causing the vehicle to stop. However, the self-driving system will still calculate the steering direction and turn the steering wheel according to the degree of deviation between the vehicle and the route, resulting in a large turn at rest;

[0082] If the vehicle is stationary and the steering wheel is turned vigorously, the tire will drag on the ground, causing excessive wear on the tire side, which will not only reduce the tire life, but also cause overload on the steering mechanism. In addition, turning the steering wheel for a long time or frequently when the vehicle is stationary will cause additional pressure on the steering gear (such as rack gear or worm gear) and connecting parts (such as steering tie rod, ball head, etc.), thereby accelerating the wear of these parts.

[0083] Therefore, in order to overcome the problem of a three-axle vehicle turning at a large angle when stationary, the following steps are provided, including:

[0084] When the current speed of the vehicle is greater than a certain value (which can be calibrated according to the actual situation, in this case it can be calibrated to 0.1m / s), the vehicle is judged to be in normal driving process, and the range of the target steering percentage is set to -100% to 100%.

[0085] When the current speed of the vehicle is less than the first speed threshold (which can be calibrated according to the actual situation, and can be calibrated to 0.02m / s in this case), the self-driving system determines that the vehicle is stationary, and then performs the following steps:

[0086] Get the actual steering percentage of the specified axis in real time. If it is greater than zero, set the actual steering percentage to the first maximum steering percentage limit value, and set zero to the first minimum steering percentage limit value; if it is less than zero, set the actual steering percentage to the first minimum steering percentage limit value, and set zero to the first maximum steering percentage limit value;

[0087] The current load of the vehicle is acquired in real time through sensors, and the corresponding second maximum steering percentage limit value is set according to different loads;

[0088] The smaller value between the first minimum steering percentage limit value and the negative second maximum steering percentage limit value is taken as the minimum target value, and the larger value between the first maximum steering percentage limit value and the second maximum steering percentage limit value is taken as the maximum target value. The range of the target steering percentage of the steering system is limited to between the minimum target value and the maximum target value.

[0089] In this way, a three-axle vehicle can effectively calculate a suitable range limit of the target steering percentage based on the actual steering percentage combined with the current load of the vehicle. When the actual steering percentage is greater than the second maximum steering percentage limit value or the actual steering percentage is less than the negative second maximum steering percentage limit value, it means that the vehicle is currently in a state of turning a larger angle. Therefore, the actual steering percentage is used as the critical value of the constraint to allow the vehicle to adjust back to the positive direction first, and then subsequent real-time adjustments are made based on the adjusted actual angle combined with the second maximum steering percentage limit value, so as to avoid the problem that the current angle of the vehicle cannot be adjusted when the steering angle corresponding to the actual steering percentage of the vehicle is outside the steering angle range allowed under the current load.

[0090] Here is an example:

[0091] 1. Assuming that the second maximum steering percentage limit value corresponding to the current vehicle load is 30%, the current target steering percentage limit range of the vehicle according to the load is: -30%~30%. However, if the actual steering percentage of the vehicle is 80%, according to the restriction logic in this case, the vehicle needs to limit the final target steering percentage range to -30~80%. Next, assuming the following three situations occur, the self-driving system executes as follows:

[0092] (1) If the self-driving system calculates a request for a 100% steering percentage, the steering system will only allow a maximum steering percentage of 80% based on the range, i.e. maintain the current angle;

[0093] (2) If the self-driving system requests a steering percentage of 50%, then based on the range, the steering system allows the steering percentage to be adjusted to 50%. At this time, the current actual steering percentage is changed to 50%. According to the restriction logic of this case, the range restriction constraint of its latest target steering percentage will be changed to -30%~50%;

[0094] (3) If the self-driving system requests a 10% turn, the steering system allows the steering percentage to be adjusted to 10% based on the range. At this time, the current actual steering percentage is changed to 10% less than the second maximum steering percentage limit value. According to the restriction logic of this case, the range limit constraint of its latest target steering percentage will become -30% to 30%.

[0095] 2. Assuming that the second maximum steering percentage limit value corresponding to the current vehicle load is 30%, the current target steering percentage limit range of the vehicle according to the load is: -30%~30%. However, if the actual steering percentage of the vehicle is -80%, according to the restriction logic in this case, the vehicle needs to limit the final target steering percentage range to -80~30%. Next, assuming the following three situations occur, the self-driving system executes as follows:

[0096] (1) If the self-driving system calculates a steering percentage request of -100%, the steering system only allows a maximum steering percentage of -80% based on the range, that is, maintaining the current angle;

[0097] (2) If the self-driving system requests a steering percentage of -50%, then based on the range, the steering system allows the steering percentage to be adjusted to -50%. At this time, the current actual steering percentage is changed to -50%. According to the restriction logic of this case, the range restriction constraint of its latest target steering percentage will be changed to -50%~30%;

[0098] (3) If the self-driving system requests a -10% turn, the steering system allows the steering percentage to be adjusted to -10% based on the range. At this time, the current actual steering percentage is changed to -10% which is greater than the second maximum steering percentage limit value. According to the restriction logic of this case, the range limit constraint of its latest target steering percentage will become -30%~30%.

[0099] In this embodiment, since the three-axle vehicle has multiple steering modes in the autonomous driving scenario of the unmanned port, and often needs to switch between multiple steering modes, in addition to driving straight, if the vehicle directly switches the steering mode to execute the change of the target turning angle during driving, the expected trajectory of the vehicle is uncertain. For example, if the vehicle is originally in the front-wheel steering mode and switches to a large-angle steering mode, the wheels of the third axle will immediately turn to the other side. The trajectory of the vehicle during the steering process is uncertain, which poses a great safety risk. Therefore, in order to solve the above safety issues when switching steering modes, before the self-driving system switches the steering mode, perform the following steps:

[0100] S1: limit the current speed of the vehicle to zero;

[0101] S2: When the current actual speed of the vehicle is less than the second speed threshold (which can be calibrated according to the actual situation, and is 0.3m / s in this embodiment), the self-driving system determines that the vehicle is about to stop. At this time, the target angle percentage of the designated axis is limited to zero, so that the wheels of the designated axis can be controlled to return to the center before the vehicle stops. Since the steering mode is switched very frequently in the unmanned port scenario, and the vehicle must stop first to allow all tires to return to the center before switching, the forward return operation before the vehicle stops can effectively save the overall time required for the subsequent steering mode switching process, ensuring that the switching efficiency is fast enough and does not affect the operation speed on site;

[0102] S3: When the current speed of the vehicle is less than the first speed threshold (which can be calibrated according to the actual situation, and can be calibrated to 0.02m / s in this case) and the absolute value of the actual steering percentage is less than the second turning angle threshold (which can be calibrated according to the actual situation, generally within 5%, indicating that the wheel has basically returned to the center position. Because the vehicle speed and tire turning angle are detected by sensors, in most cases the detection value will not be zero, but a minimum value fluctuating around zero, so a smaller threshold is used for judgment), the self-driving system sends the target steering mode to the steering system;

[0103] S4: When the actual steering mode is switched to the target steering mode, the self-driving system removes restrictions on the vehicle speed and target turning angle percentage.

[0104] By cyclically cycling the above steps, safe switching between different steering modes of the vehicle can be effectively ensured, avoiding unpredictable safety hazards caused by direct switching of steering modes during the driving of a three-axle vehicle.

[0105] Furthermore, when the absolute value of the difference between the target angle percentage and the actual angle percentage of the designated axis is calculated in real time, further judgment is made. If it is greater than the fifth difference threshold, timing is performed. When the accumulated timing time exceeds the second time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running; if it is less than the fifth difference threshold, the timing is reset to zero, and the vehicle resumes normal operation.

[0106] The fifth difference threshold is at least 1.5 times the first difference threshold, and the first time threshold is at least 1.5 times the second time threshold.

[0107] When the absolute value of the difference between the target turning angle percentage and the actual turning angle percentage of the designated axle of a three-axle vehicle is at a larger angle deviation above the fifth difference threshold, the basic steering function of the vehicle has seriously failed, and the deviation from the target turning angle percentage is too large, which is an abnormal operating condition. At this time, a shorter time accumulation is required to achieve timely diagnosis and parking. The angle deviation represented by the first difference threshold is smaller, and the tolerance can be slightly higher at this time, giving the steering system a longer recovery time. Therefore, the two are further distinguished in the setting of time thresholds.

[0108] Furthermore, when the current load of the vehicle is obtained in real time and the corresponding second maximum steering percentage limit value is set according to different loads, it specifically includes:

[0109] When the vehicle load is greater than 20 tons and less than or equal to 40 tons, the second maximum steering percentage limit value is set to 60%;

[0110] When the vehicle load is greater than 40 tons and less than or equal to 60 tons, the second maximum steering percentage limit value is set to 40%;

[0111] When the vehicle load is greater than 60 tons, the second maximum steering percentage limit value is set to 20%.

[0112] Of course, its range can also be flexibly set according to the different situations of three-axle vehicles. For three-axle vehicles with smaller load capacity, more levels of judgment and constraints can be used to effectively reduce the negative impact of large-angle turning behaviors of different types of three-axle vehicles at rest.

[0113] Furthermore, the range of the third difference threshold is 0-60%; the range of the fourth difference threshold is 0-17%; and the range of the second difference threshold is 0-17%.

[0114] Generally, the angle difference between the inner wheel and the outer wheel on the same axis depends on the turning angle, and usually does not exceed 5° at most; in the diagonal driving mode, the angle difference between the two axes does not exceed 5°; in the front wheel mode or the rear wheel mode, the angle difference between the two axes that need to be turned does not exceed 18°. Therefore, based on the judgment of these values, the range of the difference threshold is further limited, making the range value for calculation and judgment more reasonable and objective, and improving the overall judgment quality.

[0115] Based on the above overall judgment logic, the specific fault situation when the fault occurs is explained, so that operators with different professional levels can quickly identify the specific fault problem for rapid and accurate repair.

[0116] When the accumulated timing time exceeds the first time threshold, the fault reported is that there is a fault in the execution of the steering system;

[0117] When the accumulated timing time exceeds the second time threshold, the fault reported is that there is a fault in the execution of the left and right wheel angles of the specified axis;

[0118] When the steering mode is the front-wheel steering mode and the angle is greater than the first turning angle threshold, the fault reported is that the third axis has a turning angle; when the steering mode is the front-wheel steering mode and the angle is greater than the third difference threshold, the fault reported is that the turning angle difference between the first axis and the second axis is too large; this judgment method can effectively and quickly identify whether there is a fault in the front-wheel steering mode, avoiding lengthy repetition or invalid identification;

[0119] When the steering mode is the rear-wheel steering mode and the angle is greater than the first turning angle threshold, the fault reported is that the first axis has a turning angle; when the steering mode is the rear-wheel steering mode and the angle is greater than the third difference threshold, the fault reported is that the turning angle difference between the second axis and the second axis is too large; this judgment method can effectively and quickly identify whether there is a fault in the rear-wheel steering mode, avoiding lengthy repetition or invalid identification;

[0120] When the steering mode is a large-angle steering mode and the angle is greater than the first angle threshold, the reported fault is that the second axis has an angle; when the steering mode is a large-angle steering mode and the angle is greater than the first addition threshold or less than the negative first addition threshold, the reported fault is that the angle directions between the first axis and the third axis are the same or the difference is too large; this judgment idea can effectively utilize the fact that the first axis and the third axis rotate in opposite directions with positive and negative values ​​combined with addition logic to quickly identify whether there is a fault in the large-angle steering mode, avoiding lengthy repetition or invalid identification;

[0121] When the steering mode is lane change steering mode, the reported fault is that the angles of at least two specified axes are different. Since the normal state of the lane change steering mode should be that both wheels on both sides turn in the same direction and at the same angle or that both wheels on both sides return to the normal state to achieve straight driving, there are six fault conditions in the lane change steering mode. Please refer to Figure 3 , each vertical wheel arrangement in the figure represents a single-side wheel fault condition; due to the large number of fault conditions, if each axis is calculated and judged separately with other axes, it needs to be judged three times, which takes longer time. Therefore, in order to improve the judgment speed and simplify the calculation amount, the judgment ideas of any two groups can effectively improve the calculation efficiency and avoid lengthy repetition or invalid recognition;

[0122] A steering system safety protection device for a three-axle all-wheel steering vehicle, comprising:

[0123] A control module, used to send a target steering mode and a target angle percentage of a specified axis to the steering system;

[0124] The designated axis rotation angle judgment module is used to calculate the absolute value of the difference between the target rotation angle percentage and the actual rotation angle percentage of the designated axis in real time, and execute the corresponding instruction according to the result;

[0125] The coaxial left and right wheel judgment module is used to calculate the absolute value of the difference between the actual turning angle percentages of the left and right wheels in each axis in real time, and execute corresponding instructions according to the results;

[0126] The steering mode judgment module determines whether the vehicle's current actual steering module is in the front-wheel steering mode, the rear-wheel steering mode, the large-angle steering mode, or the lane-changing steering mode, and then calculates the specified axis angle of the current actual steering module, and executes the corresponding instruction according to the result; the specific calculation and judgment logic can refer to the content in the above method.

[0127] In another embodiment, an electronic device is provided, comprising:

[0128] A processor; and a memory for storing executable instructions of the processor;

[0129] Wherein, the processor is configured to execute any one of the above-mentioned steering system safety protection methods for a three-axle all-wheel steering vehicle by executing the executable instructions.

[0130] It will be appreciated by those skilled in the art that various aspects of the present invention may be implemented as a system, method or program product. Therefore, various aspects of the present invention may be specifically implemented in the following forms, namely: a complete hardware implementation, a complete software implementation (including firmware, microcode, etc.), or a combination of hardware and software, which may be collectively referred to herein as a "circuit", "module" or "system".

[0131] Refer to the following Figure 4 An electronic device 400 according to this embodiment of the present invention will be described. Figure 4 The electronic device 400 shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present invention.

[0132] like Figure 4 As shown, the electronic device 400 is in the form of a general computing device. The components of the electronic device 400 may include but are not limited to: at least one processing unit 410, at least one storage unit 420, and a bus 430 connecting different system components (including the storage unit 420 and the processing unit 410).

[0133] The storage unit stores program codes, which can be executed by the processing unit 410, so that the processing unit 410 performs the steps according to various exemplary embodiments of the present invention described in the above “Exemplary Method” section of this specification. For example, the processing unit 410 can perform the following steps: Figure 1 The steering system safety protection method of the three-axle all-wheel steering vehicle is described in the present invention.

[0134] The storage unit 420 may include a readable medium in the form of a volatile storage unit, such as a random access storage unit (RAM) 4201 and / or a cache storage unit 4202 , and may further include a read-only storage unit (ROM) 4203 .

[0135] The storage unit 420 may also include a program / utility 4204 having a set (at least one) of program modules 4205, such program modules 4205 including but not limited to: an operating system, one or more application programs, other program modules, and program data, each of which or some combination may include an implementation of a network environment.

[0136] Bus 430 may represent one or more of several types of bus structures, including a memory unit bus or memory unit controller, a peripheral bus, an accelerated graphics port, a processing unit, or a local bus using any of a variety of bus architectures.

[0137] The electronic device 400 may also communicate with one or more external devices 500 (e.g., keyboards, pointing devices, Bluetooth devices, etc.), may also communicate with one or more devices that enable a user to interact with the electronic device 400, and / or may communicate with any device that enables the electronic device 400 to communicate with one or more other computing devices (e.g., routers, modems, etc.). This communication may be performed through an input / output (I / O) interface 450. In addition, the electronic device 400 may also communicate with one or more networks (e.g., local area networks (LANs), wide area networks (WANs), and / or public networks, such as the Internet) through a network adapter 460. As shown, the network adapter 460 communicates with other modules of the electronic device 400 through a bus 430. It should be understood that, although not shown in the figure, other hardware and / or software modules may be used in conjunction with the electronic device 400, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems, etc.

[0138] Through the description of the above implementation, it is easy for those skilled in the art to understand that the example implementation described here can be implemented by software, or by software combined with necessary hardware. Therefore, the technical solution according to the implementation of the present disclosure can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.) or on a network, and includes a number of instructions to enable a computing device (which can be a personal computer, a server, a terminal device, or a network device, etc.) to execute the method according to the implementation of the present disclosure.

[0139] In yet another embodiment, a computer-readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the steering system safety protection method of a three-axle all-wheel steering vehicle described in any one of the above is implemented.

[0140] In an exemplary embodiment of the present disclosure, a computer-readable storage medium is also provided, on which a program product capable of implementing the above method of the present specification is stored. In some possible implementations, various aspects of the present invention can also be implemented in the form of a program product, which includes a program code, and when the program product is run on a terminal device, the program code is used to enable the terminal device to execute the steps according to various exemplary embodiments of the present invention described in the above "Exemplary Method" section of the present specification.

[0141] A program product for implementing the above method according to an embodiment of the present invention is described, which can adopt a portable compact disk read-only memory (CD-ROM) and include program code, and can be run on a terminal device, such as a personal computer. However, the program product of the present invention is not limited thereto, and in this document, a readable storage medium can be any tangible medium containing or storing a program, which can be used by or in combination with an instruction execution system, an apparatus or a device.

[0142] The program product may be any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. The readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination thereof. More specific examples (non-exhaustive list) of readable storage media include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof.

[0143] Computer readable signal media may include data signals propagated in baseband or as part of a carrier wave, in which readable program code is carried. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. Readable signal media may also be any readable medium other than a readable storage medium, which may send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0144] The program code embodied on the readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wired, optical cable, RF, etc., or any suitable combination of the foregoing.

[0145] Program code for performing the operations of the present invention may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, C++, etc., and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, as a separate software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server. In the case of a remote computing device, the remote computing device may be connected to the user computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0146] It should be noted that, although several modules or units of the device for action execution are mentioned in the above detailed description, this division is not mandatory. In fact, according to the embodiments of the present disclosure, the features and functions of two or more modules or units described above can be embodied in one module or unit. On the contrary, the features and functions of one module or unit described above can be further divided into multiple modules or units to be embodied.

[0147] In addition, although the steps of the method in the present disclosure are described in a specific order in the drawings, this does not require or imply that the steps must be performed in this specific order, or that all the steps shown must be performed to achieve the desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps, etc.

[0148] Through the description of the above implementation, it is easy for those skilled in the art to understand that the example implementation described here can be implemented by software, or by combining software with necessary hardware. Therefore, the technical solution according to the implementation of the present disclosure can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.) or on a network, and includes several instructions to enable a computing device (which can be a personal computer, a server, a mobile terminal, or a network device, etc.) to execute the method according to the implementation of the present disclosure.

[0149] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

Claims

1. A steering system safety protection method for a three-axle all-wheel steering vehicle, characterized in that: include: Its three-axle all-wheel steering vehicle includes a first axle located at the front of the vehicle, a second axle located at the center of the vehicle and a third axle located at the rear of the vehicle; The target steering mode and the target turning angle percentage of the specified axis are sent to the steering system through the self-driving control system of the steering vehicle; The absolute value of the difference between the target angle percentage and the actual angle percentage of the specified axis is calculated in real time. If it is greater than the first difference threshold, timing is performed. When the accumulated timing time exceeds the first time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running. If it is less than the first difference threshold, the timing is reset to zero and the vehicle resumes normal operation. The absolute value of the difference between the actual turning angle percentages of the left wheel and the right wheel of each axis is calculated in real time respectively. If it is greater than the second difference threshold, timing is performed. When the accumulated timing time exceeds the second time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running; if it is less than the second difference threshold, the timing is reset to zero and the vehicle resumes normal operation; Select one of the following four steps to execute according to the actual steering mode: When the actual steering mode is the front-wheel steering mode, the larger value of the absolute value of the actual turning angle percentage of the left wheel and the right wheel of the third axle is first taken. If it is greater than the first turning angle threshold, timing is performed. When the accumulated timing time exceeds the third time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running; if it is less than the first turning angle threshold, the timing is reset, and the absolute value of the difference between the actual turning angle percentages of the two tires on either side of the first axle and the second axle is further calculated. If it is greater than the third difference threshold, timing is performed. When the accumulated timing time exceeds the third time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running. If it is less than the third difference threshold, the timing is reset, and the vehicle resumes normal operation. When the actual steering mode is the rear-wheel steering mode, the larger value of the absolute value of the actual turning angle percentage of the left wheel and the right wheel of the first axle is first taken. If it is greater than the first turning angle threshold, timing is performed. When the accumulated timing time exceeds the third time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running; if it is less than the first turning angle threshold, the timing is reset, and the absolute value of the difference between the actual turning angle percentages of the two tires on either side of the second axle and the third axle is further calculated. If it is greater than the third difference threshold, timing is performed. When the accumulated timing time exceeds the third time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running. If it is less than the third difference threshold, the timing is reset, and the vehicle resumes normal operation. When the actual steering mode is the large-angle steering mode, the larger value of the absolute value of the actual turning angle percentage of the left wheel and the right wheel of the second axle is first taken. If it is greater than the first turning angle threshold, timing is performed. When the cumulative timing time exceeds the first time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running; if it is less than the first turning angle threshold, the timing is reset, and the addition value between the actual turning angle percentages of the two tires on either side of the first axle and the third axle is further calculated. If it is greater than the first addition threshold or less than the negative first addition threshold, timing is performed. When the cumulative timing time exceeds the third time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running. If it is less than the first addition threshold or greater than the negative first addition threshold, the timing is reset, and the vehicle resumes normal operation. When the actual steering mode is the lane change steering mode, any two groups of the first axis and the second axis or the second axis and the third axis or the first axis and the third axis are taken, and the absolute value of the difference between the actual turning angle percentages of the two tires on the same side in each group is calculated respectively, and the larger value of the two absolute values ​​is taken. If the larger value is greater than the fourth difference threshold, timing is performed. When the timing accumulated time exceeds the first time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running; if it is less than the fourth difference threshold, the timing is reset to zero, and the vehicle resumes normal operation; When the current speed of the vehicle is less than the first speed threshold, the self-driving system determines that the vehicle is stationary and performs the following steps: The actual steering percentage of the specified axis is obtained in real time. If it is greater than zero, the actual steering percentage is set as the first maximum steering percentage limit value, and zero is set as the first minimum steering percentage limit value; If it is less than zero, the actual steering percentage is set as the first minimum steering percentage limit value, and zero is set as the first maximum steering percentage limit value; Obtain the current load of the vehicle in real time, and set the corresponding second maximum steering percentage limit value according to different loads; The smaller value between the first minimum steering percentage limit value and the negative second maximum steering percentage limit value is taken as the minimum target value, and the larger value between the first maximum steering percentage limit value and the second maximum steering percentage limit value is taken as the maximum target value. The range of the target steering percentage of the steering system is limited to between the minimum target value and the maximum target value.

2. The steering system safety protection method for a three-axle all-wheel steering vehicle according to claim 1 is characterized in that: include: Before the self-driving system switches steering mode, perform the following steps: S1: limit the current speed of the vehicle to zero; S2: When the current actual speed of the vehicle is less than the second speed threshold, the self-driving system determines that the vehicle is about to stop, and at this time limits the target turning angle percentage of the designated axis to zero, so as to control the wheel of the designated axis to return to the center before the vehicle stops; S3: When the current speed of the vehicle is less than the first speed threshold and the absolute value of the actual steering percentage is less than the second turning angle threshold, the self-driving system sends a target steering mode to the steering system; S4: When the actual steering mode is switched to the target steering mode, the self-driving system removes restrictions on the vehicle speed and target turning angle percentage.

3. The steering system safety protection method for a three-axle all-wheel steering vehicle according to claim 1, characterized in that: include: When the absolute value of the difference between the target angle percentage and the actual angle percentage of the specified axis is calculated in real time, further judgment is made. If it is greater than the fifth difference threshold, timing is performed. When the accumulated timing time exceeds the second time threshold, a fault is reported, and the vehicle is speed-limited or prohibited from running; if it is less than the fifth difference threshold, the timing is reset to zero and the vehicle resumes normal operation; The fifth difference threshold is at least 1.5 times the first difference threshold, and the first time threshold is at least 1.5 times the second time threshold.

4. The steering system safety protection method for a three-axle all-wheel steering vehicle according to claim 1, characterized in that: When the current load of the vehicle is obtained in real time and the corresponding second maximum steering percentage limit value is set according to different loads, it specifically includes: When the vehicle load is greater than 20 tons and less than or equal to 40 tons, the second maximum steering percentage limit value is set to 60%; When the vehicle load is greater than 40 tons and less than or equal to 60 tons, the second maximum steering percentage limit value is set to 40%; When the vehicle load is greater than 60 tons, the second maximum steering percentage limit value is set to 20%.

5. The steering system safety protection method for a three-axle all-wheel steering vehicle according to claim 1, characterized in that: The range of the third difference threshold is 0-60%; the range of the fourth difference threshold is 0-17%; and the range of the second difference threshold is 0-17%.

6. The steering system safety protection method for a three-axle all-wheel steering vehicle according to claim 1, characterized in that: When the accumulated timing time exceeds the first time threshold, the fault reported is that there is a fault in the execution of the steering system; When the accumulated timing time exceeds the second time threshold, the fault reported is that there is a fault in the execution of the left and right wheel angles of the specified axis; When the steering mode is the front-wheel steering mode and the angle is greater than the first turning angle threshold, the fault reported is that the third axis has a turning angle; When the steering mode is the front-wheel steering mode and the difference is greater than the third difference threshold, the fault reported is that the difference between the steering angles of the first axis and the second axis is too large; When the steering mode is the rear-wheel steering mode and the angle is greater than the first turning angle threshold, the fault reported is that the first axis has a turning angle; When the steering mode is the rear-wheel steering mode and the difference is greater than the third difference threshold, the fault reported is that the difference between the second axis and the second axis is too large; When the steering mode is a large-angle steering mode and the angle is greater than the first turning angle threshold, the reported fault is that the second axis has a turning angle; When the steering mode is a large-angle steering mode and is greater than the first addition threshold or less than the negative first addition threshold, the reported fault is that the steering angle directions between the first axis and the third axis are the same or the difference is too large; When the steering mode is the lane change steering mode, the reported fault is that the steering angles of at least two specified axes are different.

7. A three-axle all-wheel steering vehicle steering system safety protection device, characterized in that: The device is used to execute the security protection method described in any one of claims 1 to 6, comprising: A control module, used to send a target steering mode and a target angle percentage of a specified axis to the steering system; The designated axis rotation angle judgment module is used to calculate the absolute value of the difference between the target rotation angle percentage and the actual rotation angle percentage of the designated axis in real time, and execute the corresponding instruction according to the result; The coaxial left and right wheel judgment module is used to calculate the absolute value of the difference between the actual turning angle percentages of the left and right wheels in each axis in real time, and execute corresponding instructions according to the results; The steering mode judgment module determines whether the vehicle's current actual steering module is in the front-wheel steering mode, the rear-wheel steering mode, the large-angle steering mode, or the lane-changing steering mode, and then calculates the specified axis angle of the current actual steering module, and executes the corresponding instructions based on the result.

8. An electronic device, characterized in that: include: processor; and a memory for storing executable instructions for the processor; Wherein, the processor is configured to execute the security protection method according to any one of claims 1 to 6 by executing the executable instructions.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the security protection method described in any one of claims 1 to 6 is implemented.

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