Active rear-axle steering control system and method for large bus, and storage medium

Abstract

The present invention relates to the field of buses, and specifically relates to an active rear-axle steering control system and method for a large bus, and a storage medium. A column angle sensor is provided on a steering column connected to a steering wheel, such that a vehicle control unit can control the rotation of a rear-axle steering apparatus by monitoring a steering angle of the steering wheel. Moreover, a kingpin steering angle sensor is provided on a front-axle steering apparatus, a correspondence between the steering angle of the steering wheel and a steering angle of front wheels is used as a start condition for active rear-axle steering, and when the steering angle of the steering wheel does not correspond to the steering angle of the front wheels, a rear axle is locked in a centered position, and only the front-axle steering apparatus performs steering motion. Therefore, a driver can easily perform a steering operation, thereby improving the steering safety of a vehicle.

Description

A large passenger bus rear axle active steering control system, method and storage medium Technical Field

[0001] This invention relates to the field of buses, specifically to a large bus rear axle active steering control system, method, and storage medium. Background Technology

[0002] Large buses, due to their longer wheelbase, have a larger turning radius compared to ordinary buses, resulting in lower turning efficiency and making them less suitable for turning and navigating in confined spaces. Most buses use front-wheel steering; adding rear-wheel steering to this system shifts the vehicle's steering center forward, reducing the turning radius and improving maneuverability.

[0003] Existing active steering control systems for large buses primarily involve installing an angle sensor on each of the front and rear axles. The vehicle controller determines the steering angle of the front axle and controls the rear axle to make corresponding steering movements, thus ensuring vehicle stability to a certain extent during active rear axle steering. However, since the rear axle steering is solely related to the front axle angle and entirely controlled by a computer, it cannot provide sufficient steering feedback to the driver. Over long-term operation, wear and tear on components such as tires and ball joints, along with changes in four-wheel alignment parameters, can lead to a mismatch between the steering wheel and the vehicle's steering relationship. In the face of sudden situations, with active rear axle steering involved, the driver may find it difficult to predict the required steering wheel angle, resulting in a larger turning radius and lane circle than actually needed, thus creating a dangerous situation. Summary of the Invention

[0004] The technical problem this application aims to solve is to provide a large bus rear axle active steering control system, method, and storage medium. The vehicle controller can control the rotation of the rear axle steering device by monitoring the rotation angle of the steering wheel. At the same time, the corresponding relationship between the steering wheel and the front wheel rotation angles is used as the activation condition for the rear axle active steering. In case of abnormality, the rear axle is locked in the center, making it easy for the driver to perform steering operations and improving the safety of vehicle steering.

[0005] This application adopts the following technical solution: a large bus rear axle active steering control system, including a front axle steering device, a rear axle steering device, a vehicle controller, a steering column, a column angle sensor, and a kingpin angle sensor. The front axle steering device and the rear axle steering device are connected. The steering column is connected to the bus's steering wheel and the front axle steering device respectively. The column angle sensor is fixed on the steering column. The kingpin angle sensor is fixed on the front axle steering device. The front axle steering device is fixedly connected to the bus's front wheels. The vehicle controller is connected to the front axle steering device, the rear axle steering device, the column angle sensor, and the kingpin angle sensor respectively.

[0006] Furthermore, the front axle steering device includes a front oil reservoir, a front oil pump, a front axle steering gear, a drop arm, a tie rod, a front axle pivot arm, and a front axle kingpin. The front oil pump is connected to the front oil reservoir and the front axle steering gear, the front axle steering gear is connected to the drop arm, the drop arm, the tie rod, and the front axle pivot arm are sequentially connected to the front axle kingpin, the front axle kingpin is fixedly connected to the front wheel, and the kingpin angle sensor is fixed to the front axle kingpin.

[0007] Furthermore, the rear axle steering device includes a rear oil reservoir, a rear oil pump, a rear axle steering cylinder, and a rear axle arm. The rear oil pump is connected to both the rear oil reservoir and the rear axle steering cylinder. A piston is installed inside the rear axle steering cylinder, and the rear axle arm is connected to the piston.

[0008] More preferably, it also includes a rear oil pump controller connected to the rear oil pump, the rear oil pump controller being connected to the rear axle steering cylinder.

[0009] This application also provides a rear axle active steering control method, which is based on any of the above-mentioned large bus rear axle active steering control systems and includes the following steps:

[0010] S1, the column angle sensor and the kingpin angle sensor collect the rotation angle data of the steering wheel and the front wheels, and transmit the collected rotation angle data to the vehicle controller;

[0011] S2a. The vehicle controller determines that the rotation angle of the steering wheel corresponds to the rotation angle of the front wheels, and then controls the rear axle steering device to rotate accordingly based on the rotation angle of the steering wheel.

[0012] S3a. The bus completes steering by the combined action of the front axle steering system and the rear axle steering system.

[0013] or:

[0014] S2b: If the vehicle controller determines that the steering wheel rotation angle does not correspond to the front wheel rotation angle, it will control the rear axle steering device to center and lock the rear axle steering device.

[0015] S3b: The bus can steer using only the front axle steering device.

[0016] Preferably, before S2a or S2b, a condition is added to determine whether the rear axle steering device is centered and locked, using the current speed of the bus as the criterion:

[0017] When the vehicle speed exceeds the preset vehicle speed threshold, the vehicle controller controls the rear axle steering device to center and lock the rear axle steering device, and then enters S3b.

[0018] Alternatively, if the vehicle speed is less than a preset speed threshold, then proceed to S2a or S2b.

[0019] More preferably, the current gear of the bus is used as a prerequisite before determining the vehicle speed:

[0020] When the bus is in neutral and the neutral speed is below the minimum threshold, the vehicle controller controls the rear axle steering device to center and lock the rear axle steering device, and then enters S3b.

[0021] Alternatively, when the bus is in forward, reverse, or neutral and the speed in neutral exceeds the minimum threshold, it will enter S2a or S2b.

[0022] Preferably, before S2a or S2b, a condition is added to determine whether the rear axle steering device is centered and locked, based on whether the passenger vehicle has entered the bus stop area:

[0023] When the vehicle controller detects that the bus has entered the bus stop area and receives the door opening signal, the vehicle controller controls the rear axle steering device to center and lock the rear axle steering device, and then enters S3b.

[0024] Alternatively, when the vehicle controller detects that the bus has left the bus stop area, it will enter S2a or S2b.

[0025] Preferably, before S3a, the deviation between the actual steering angle and the target steering angle of the rear axle steering device is added as a criterion for determining whether the rear axle steering device returns to the centering lock state:

[0026] When the deviation between the actual steering angle and the target steering angle of the rear axle steering device is greater than the preset angle, the rear axle returns to the centering state and the rear axle steering device is locked, entering S3b.

[0027] Alternatively, if the deviation between the actual steering angle and the target steering angle of the rear axle steering device is less than the preset angle, then proceed to S3a.

[0028] This application also provides a computer-readable storage medium storing computer-executable instructions, which implement the method when a processor executes the computer-executable instructions.

[0029] Compared with the prior art, the beneficial effects achieved by the present invention include:

[0030] This application, by installing a column angle sensor on the steering column connected to the steering wheel, allows the vehicle controller to control the rotation of the rear axle steering device by monitoring the steering wheel's rotation angle. Simultaneously, a kingpin angle sensor is installed on the front axle steering device. The correspondence between the steering wheel and front wheel rotation angles is used as the activation condition for the rear axle's active steering. When the relationship between the steering wheel and front wheel rotation angles is not corresponding, the rear axle is locked in center, and only the front axle steering device participates in the steering movement. This makes it easier for the driver to perform steering operations and improves the safety of vehicle steering. Attached Figure Description

[0031] Figure 1 is a schematic diagram of the overall structure of the control system according to an embodiment of this application;

[0032] Figure 2 is a graph showing the relationship between the steering wheel rotation angle and the rotation angle of the left front wheel or the right front wheel in an embodiment of this application.

[0033] In the diagram: 1. Front oil reservoir; 2. Front oil pump; 3. Steering wheel; 4. Column angle sensor; 5. Front axle steering gear; 6. Drop arm; 7. Tie rod; 8. Front axle lever; 9. Rear oil pump; 10. Piston; 11. Rear oil reservoir; 12. Rear axle lever. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0035] Therefore, the following detailed description of embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely illustrates some embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0036] Example

[0037] Referring to Figure 1, this embodiment provides a large bus rear axle active steering control system, including a front axle steering device, a rear axle steering device, a vehicle controller, a steering column, a column angle sensor 4, and a kingpin angle sensor. The front axle steering device and the rear axle steering device are connected. The steering column is connected to the bus's steering wheel 3 and the front axle steering device, respectively. The column angle sensor 4 is fixed to the steering column, and the kingpin angle sensor is fixed to the front axle steering device. The front axle steering device is fixedly connected to the bus's front wheels. The vehicle controller is connected to the front axle steering device, the rear axle steering device, the column angle sensor 4, and the kingpin angle sensor, respectively. The column angle sensor 4 collects the rotation angle of the steering wheel 3 connected to the steering column. The vehicle controller transmits control commands via CAN signals, controlling the rear axle steering device to rotate by the corresponding angle based on the rotation angle of the steering wheel 3. This results in a more sensitive and rapid steering response, a more direct and intense steering feel for the driver, and a more comfortable driving experience.

[0038] In this embodiment, the signals transmitted by the vehicle controller via CAN communication include: ignition signal: confirming whether the vehicle has started; column angle signal: read when the rear axle is turning to confirm the steering angle; front axle kingpin angle signal: cross-checked with the column angle signal to determine whether to perform active rear axle steering; vehicle speed signal: determining the vehicle speed; gear shift signal: determining the vehicle gear; DTC fault code signal: vehicle fault feedback; door opening signal: when the vehicle speed is below a minimum threshold, the vehicle controller allows the door to open; stop information signal: determining whether to enter a bus stop; front oil pump signal: providing steering reference for the rear axle steering device.

[0039] Furthermore, the front axle steering device includes a front oil reservoir 1, a front oil pump 2, a front axle steering gear 5, a drop arm 6, a tie rod 7, a front axle pivot arm 8, and a front axle kingpin. The front oil pump 2 is connected to both the front oil reservoir 1 and the front axle steering gear 5. The front axle steering gear 5 is connected to the drop arm 6. The drop arm 6, tie rod 7, and front axle pivot arm 8 are sequentially connected to the front axle kingpin. The front axle kingpin is fixedly connected to the front wheel. The kingpin angle sensor is fixed to the front axle kingpin. A kingpin angle sensor is installed on the front axle kingpin to collect the steering angle of the front axle. By comparing the steering angle of the steering wheel 3 with the steering angle of the front axle, it is verified whether a pre-set correspondence is met. This correspondence is shown in Figure 2, where the horizontal axis represents the steering angle of the steering wheel, and the vertical axis represents the steering angle of the front wheel, with left turn being positive. When the correspondence is not met, it indicates a significant error in steering wheel 3 or the four-wheel alignment. Continuing to initiate rear-wheel steering makes it difficult for the driver to predict the appropriate steering wheel 3 angle for evasive maneuvers in unexpected situations, often leading to oversteering and potential danger. By establishing a correspondence between steering wheel 3 and the front axle steering angle as a condition for activating the rear axle steering system, the driver is alerted to timely vehicle maintenance. In emergency situations, the rear axle is forcibly locked in center, with only the front axle participating in steering. This facilitates the driver's prediction of the steering wheel 3 rotation angle, thus preventing potential hazards.

[0040] The working principle of the front axle steering device is as follows: The vehicle controller controls the front oil pump 2 to work. When the steering wheel 3 of the bus turns left and right, the clearance of the valve inside the front axle steering gear 5 will change. The high-pressure oil output by the front oil pump 2 forms a pressure difference inside the front axle steering gear 5, which pushes the drop arm 6 to rotate. The drop arm 6 drives the tie rod 7 and the front axle arm 8 connected to it to move, which ultimately causes the front wheel to rotate around the front axle kingpin. Finally, the front wheel rotates, and the kingpin angle sensor collects the rotation angle of the front wheel and transmits it to the vehicle controller.

[0041] Furthermore, the rear axle steering device includes a rear oil reservoir 11, a rear oil pump 9, a rear axle steering cylinder, and a rear axle lever 12. The rear oil pump 9 is connected to both the rear oil reservoir 11 and the rear axle steering cylinder. A piston 10 is installed inside the rear axle steering cylinder, and the rear axle lever 12 is connected to the piston 10. The rear axle steering device also includes a rear oil pump controller connected to the rear oil pump 9, and the rear oil pump controller is connected to the rear axle steering cylinder. The rear oil pump controller controls the steering angle of the rear axle steering device and the rear axle centering lock state by controlling the stroke of the piston 10 in the rear axle steering cylinder. By monitoring the stroke of the piston 10, the position and deflection of the rear axle steering device can be determined, facilitating correction and locking of the control system and further improving the safety of the rear axle active steering.

[0042] When the bus is traveling straight normally, the steering angle of steering wheel 3 is 0, the front axle is centered, and the rear axle is centered.

[0043] This application also provides a rear axle active steering control method, which is based on any of the above-mentioned large bus rear axle active steering control systems and includes the following steps:

[0044] S1, the column angle sensor 4 and the kingpin angle sensor collect the rotation angle data of the steering wheel 3 and the front wheel, and transmit the collected rotation angle data to the vehicle controller.

[0045] S2a. The vehicle controller determines that the rotation angle of the steering wheel 3 corresponds to the rotation angle of the front wheels, and then controls the rear axle steering device to rotate accordingly based on the rotation angle of the steering wheel 3.

[0046] S3a. The bus completes steering by the combined action of the front axle steering system and the rear axle steering system.

[0047] or:

[0048] S2b: If the vehicle controller determines that the rotation angle of the steering wheel 3 does not correspond to the rotation angle of the front wheels, it will control the rear axle steering device to center and lock the rear axle steering device.

[0049] S3b: The bus can steer using only the front axle steering device.

[0050] Preferably, before S2a or S2b, a condition is added to determine whether the rear axle steering device is centered and locked, using the current speed of the bus as the criterion:

[0051] When the vehicle speed exceeds the preset vehicle speed threshold, the vehicle controller controls the rear axle steering device to center and lock the rear axle steering device, and then enters S3b.

[0052] Alternatively, if the vehicle speed is less than a preset speed threshold, then proceed to S2a or S2b.

[0053] In this embodiment, the preset vehicle speed threshold is 30 km / h. When the vehicle speed is greater than or equal to 30 km / h, the rear oil pump controller controls the piston 10 to center the rear axle and lock the rear axle steering cylinder. Because large buses have a high center of gravity, when the vehicle speed is high, active steering of the rear wheels can easily cause the rear of the bus to drift or fishtail. Therefore, setting a vehicle speed threshold can further improve the driving safety of the bus.

[0054] More preferably, the current gear of the bus is used as a prerequisite before determining the vehicle speed:

[0055] When the bus is in neutral and the neutral speed is below the minimum threshold, the vehicle controller controls the rear axle steering device to center and lock the rear axle steering device, and then enters S3b.

[0056] Alternatively, when the bus is in forward, reverse, or neutral and the speed in neutral exceeds the minimum threshold, it will enter S2a or S2b.

[0057] In this embodiment, the minimum threshold is set to 0.2 km / h to ensure that the rear wheel steering device can also operate when the bus is coasting in neutral. When the bus is coasting in neutral and the speed is lower than the minimum threshold and is about to stop, the rear axle is locked in the center to prevent the rear axle from stopping in the steering state and the rear wheels from protruding from the vehicle body and causing danger to pedestrians or vehicles.

[0058] Preferably, before S2a or S2b, a condition is added to determine whether the rear axle steering device is centered and locked, based on whether the passenger vehicle has entered the bus stop area:

[0059] When the vehicle controller detects that the bus has entered the bus stop area and receives the door opening signal, the vehicle controller controls the rear axle steering device to center and lock the rear axle steering device, and then enters S3b.

[0060] Alternatively, when the vehicle controller detects that the bus has left the bus stop area, it will enter S2a or S2b.

[0061] Bus stops are crowded. When a bus enters or leaves the bus stop, if the rear axle steering device engages in steering, the rear wheels will protrude beyond the vehicle body, which can easily cause danger to people waiting at the bus stop. Therefore, it is necessary to lock the rear axle steering device in the center at this time to prevent the rear wheels from crossing the curb and causing danger.

[0062] In this embodiment, the time it takes for the doors to close can also be used as a condition for restarting the rear axle steering device. When a bus is about to leave a bus stop, it usually closes its doors. Five seconds after the doors close, the rear axle steering device is activated, thereby improving the sensitivity of the bus turning away from the bus stop in traffic jams.

[0063] Preferably, before S3a, the deviation between the actual steering angle and the target steering angle of the rear axle steering device is added as a criterion for determining whether the rear axle steering device returns to the centering lock state:

[0064] When the deviation between the actual steering angle and the target steering angle of the rear axle steering device is greater than the preset angle, the rear axle returns to the centering state and the rear axle steering device is locked, entering S3b.

[0065] Alternatively, if the deviation between the actual steering angle and the target steering angle of the rear axle steering device is less than the preset angle, then proceed to S3a.

[0066] Over long-term operation, the rear axle steering system of a bus is prone to wear and tear, which can lead to errors. When the actual steering angle of the rear axle steering system deviates from the target steering angle by more than 3 degrees, it indicates that the rear axle steering system needs to be repaired. If the rear axle steering system continues to participate in steering, it may cause the driver to misjudge the steering of the vehicle and cause danger. Therefore, the rear axle needs to be locked and centered.

[0067] This application also provides a computer-readable storage medium storing computer-executable instructions, which implement the method when a processor executes the computer-executable instructions.

[0068] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this application as described above, which are not provided in detail for the sake of brevity.

[0069] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.

Claims

1. A large passenger bus rear axle active steering control system, characterized in that, It includes a front axle steering device, a rear axle steering device, a vehicle controller, a steering column, a column angle sensor (4), and a kingpin angle sensor. The front axle steering device and the rear axle steering device are connected. The steering column is connected to the steering wheel (3) of the bus and the front axle steering device, respectively. The column angle sensor (4) is fixed on the steering column. The kingpin angle sensor is fixed on the front axle steering device. The front axle steering device is fixedly connected to the front wheel of the bus. The vehicle controller is connected to the front axle steering device, the rear axle steering device, the column angle sensor (4), and the kingpin angle sensor, respectively.

2. The rear axle active steering control system according to claim 1, characterized in that, The front axle steering device includes a front oil reservoir (1), a front oil pump (2), a front axle steering gear (5), a drop arm (6), a tie rod (7), a front axle pivot arm (8), and a front axle kingpin. The front oil pump (2) is connected to the front oil reservoir (1) and the front axle steering gear (5) respectively. The front axle steering gear (5) is connected to the drop arm (6). The drop arm (6), tie rod (7), and front axle pivot arm (8) are connected to the front axle kingpin in sequence. The front axle kingpin is fixedly connected to the front wheel. The kingpin angle sensor is fixed to the front axle kingpin.

3. The rear axle active steering control system according to claim 1, characterized in that, The rear axle steering device includes a rear oil reservoir (11), a rear oil pump (9), a rear axle steering cylinder, and a rear axle arm (12). The rear oil pump (9) is connected to the rear oil reservoir (11) and the rear axle steering cylinder, respectively. A piston (10) is provided inside the rear axle steering cylinder, and the rear axle arm (12) is connected to the piston (10).

4. The rear axle active steering control system according to claim 3, characterized in that, It also includes a rear oil pump controller connected to the rear oil pump (9), the rear oil pump controller being connected to the rear axle steering cylinder.

5. A rear axle active steering control method, characterized in that, The rear axle active steering control method is based on the large bus rear axle active steering control system according to any one of claims 1-4, and the rear axle active steering control method includes the following steps: S1, the column angle sensor (4) and the kingpin angle sensor collect the rotation angle data of the steering wheel (3) and the front wheel, and transmit the collected rotation angle data to the vehicle controller; S2a, The vehicle controller determines that the rotation angle of the steering wheel (3) corresponds to the rotation angle of the front wheel, and then controls the rear axle steering device to rotate accordingly based on the rotation angle of the steering wheel (3). S3a. The bus completes steering by the combined action of the front axle steering system and the rear axle steering system. or: S2b, the vehicle controller determines that the rotation angle of the steering wheel (3) does not correspond to the rotation angle of the front wheels, then controls the rear axle steering device to be centered and locks the rear axle steering device. S3b: The bus can steer using only the front axle steering device.

6. The rear axle active steering control method according to claim 5, characterized in that, Add a criterion before S2a or S2b: use the current speed of the bus as the criterion for determining whether the rear axle steering device is centered and locked. When the vehicle speed exceeds the preset vehicle speed threshold, the vehicle controller controls the rear axle steering device to center and lock the rear axle steering device, and then enters S3b. Alternatively, if the vehicle speed is less than a preset speed threshold, then proceed to S2a or S2b.

7. The rear axle active steering control method according to claim 6, characterized in that, Before determining the vehicle speed, the current gear position of the bus should be used as a prerequisite: When the bus is in neutral and the neutral speed is below the minimum threshold, the vehicle controller controls the rear axle steering device to center and lock the rear axle steering device, and then enters S3b. Alternatively, when the bus is in forward, reverse, or neutral and the speed in neutral exceeds the minimum threshold, it will enter S2a or S2b.

8. The rear axle active steering control method according to claim 5, characterized in that, Add a condition before S2a or S2b that determines whether the rear axle steering device is centered and locked, based on whether the passenger vehicle has entered the bus stop area: When the vehicle controller detects that the bus has entered the bus stop area and receives the door opening signal, the vehicle controller controls the rear axle steering device to center and lock the rear axle steering device, and then enters S3b. Alternatively, when the vehicle controller detects that the bus has left the bus stop area, it will enter S2a or S2b.

9. The rear axle active steering control method according to claim 5, characterized in that, Before S3a, the deviation between the actual steering angle and the target steering angle of the rear axle steering device is added as a criterion for determining whether the rear axle steering device returns to the centering lock state: When the deviation between the actual steering angle and the target steering angle of the rear axle steering device is greater than the preset angle, the rear axle returns to the centering state and the rear axle steering device is locked, entering S3b. Alternatively, if the deviation between the actual steering angle and the target steering angle of the rear axle steering device is less than the preset angle, then proceed to S3a.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions that, when executed by a processor, implement the method as described in any one of claims 5-9.

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