A method, system and vehicle for steer-by-wire redundant control

Abstract

This invention discloses a redundancy control method, system, and vehicle for steer-by-wire, relating to the field of automotive steering. The method includes the following steps: determining a target ratio of the wheel speed on the steering side and the wheel speed on the non-steering side based on the steering wheel angle; and adjusting at least one wheel speed on the steering side and / or the non-steering side accordingly based on the target ratio. When a steer-by-wire system malfunctions and cannot control steering, this invention can achieve the vehicle's steering function "independently" of the steering components of the steer-by-wire system. Furthermore, compared to existing redundancy technologies that rely on hardware backups, this invention essentially does not increase the vehicle's size or weight, reducing operating costs while ensuring the vehicle retains its steering function.

Description

Technical Field

[0001] This invention relates to the field of automotive steering, and more specifically to a steer-by-wire redundancy control method, system, and vehicle. Background Technology

[0002] With the continuous development of automotive electronics technology, steer-by-wire technology will gradually be widely used in automobiles. Because there is no direct mechanical connection between the steering wheel and the steering wheels in a steer-by-wire system, if the system malfunctions while the vehicle is in motion, the vehicle will be unable to maintain its steering function and will generally only be able to make an emergency stop, which can easily lead to traffic accidents or traffic congestion.

[0003] To address the aforementioned issues, relevant technologies can be broadly categorized into two types: hardware-based redundancy and software-based fault-tolerant algorithms. Hardware redundancy primarily improves system fault tolerance by providing backups for critical and fault-prone components. However, this method increases system size and weight, resulting in higher costs. Software redundancy relies on controller fault-tolerant algorithms to enhance overall system redundancy, thereby improving fault tolerance. This method controls the remaining, normally functioning steering system components after a failure without altering the steering system structure or adding excessive equipment. However, when critical steering system components malfunction (i.e., a failure to control steering), normal vehicle steering cannot be guaranteed. Summary of the Invention

[0004] In view of the deficiencies in the existing technology, the technical problem solved by the present invention is: how to realize the steering function of the car while reasonably controlling the cost when the steer-by-wire system fails to control the steering.

[0005] To achieve the above objectives, in a first aspect, embodiments of this application provide a steer-by-wire redundancy control method, defining two wheels on one side with the same steering direction as the steering wheel as steering-side wheels, and two wheels on the other side as non-steering-side wheels; characterized in that the method includes the following steps: determining a target ratio of the steering-side wheel speed and the non-steering-side wheel speed according to the steering wheel angle, and adjusting at least one steering-side and / or non-steering-side wheel speed according to the target ratio.

[0006] In conjunction with the first aspect, in one implementation, the method includes the following steps: when the vehicle speed S is greater than a preset safety upper limit threshold v′, braking is performed to decelerate until S = v′; when S ≤ v′ and the steering wheel is detected to be rotating, the target ratio is determined based on the steering wheel angle; the wheel speed on the steering side is decelerated until the actual ratio reaches the target ratio.

[0007] In conjunction with the first aspect, in one embodiment, the method further includes the following steps: pre-setting a safety lower limit threshold v″, and controlling S to prevent it from exceeding v″ after S≤v″; when S≤v″ and a steering wheel rotation and vehicle acceleration signal are detected, determining the target ratio based on the steering wheel angle; under the condition of S≤v″, making the actual ratio reach the target ratio by changing the wheel speed on the non-steering side and / or the wheel speed on the steering side.

[0008] In conjunction with the first aspect, in one embodiment, the specific process of making the actual ratio reach the target ratio by changing the non-steering wheel speed v2 and the steering wheel speed v1 includes: after accelerating v2, if the target ratio is still not reached under the condition that S≤v″, then while keeping S from increasing, continue to accelerate v2 while decelerating v1 until the actual ratio reaches the target ratio.

[0009] In conjunction with the first aspect, in one embodiment, the step of adjusting the steering wheel angle δ... sw The formula for calculating the target ratio k of the steering side wheel speed v1 and the non-steering side wheel speed v2 is as follows: Where R represents the target turning radius, B represents the track width, L represents the wheelbase, and i represents the steering ratio.

[0010] In conjunction with the first aspect, in one implementation method, if during the execution of the method... Then the subsequent process is terminated, and the speed difference between v2 and v1 is reduced until...

[0011] In conjunction with the first aspect, in one implementation, the triggering condition of the method is: δ sw i-δ≥δ2, and δ<δ1, where δ sw δ represents the steering wheel angle, δ represents the steering wheel angle, δ2 represents the preset fault threshold, and δ1 represents the preset straight line determination threshold.

[0012] Secondly, embodiments of this application provide a steer-by-wire redundancy control system, which includes a control unit for executing the steer-by-wire redundancy control method described in the first aspect or its embodiments.

[0013] In conjunction with the second aspect, in one embodiment, the system further includes a fault diagnosis unit, a steering wheel angle sensor, a tire angle sensor, a brake sensor, a wheel speed sensor, and a wheel speed controller.

[0014] The fault diagnosis unit is used to: send a working signal to the control unit when the triggering condition described in claim 7 is detected;

[0015] The steering wheel angle sensor is used to: collect the steering wheel angle and feed it back to the control unit;

[0016] The tire angle sensor is used to: collect the tire steering angle and feed it back to the control unit;

[0017] The brake sensor is used to: collect vehicle braking signals and feed them back to the control unit;

[0018] Wheel speed sensors are used to: collect wheel speeds on the steering side and non-steering side and feed them back to the control unit;

[0019] The wheel speed controller is used to control the wheel speed on the steering side and the wheel speed on the non-steering side according to the instructions of the control unit.

[0020] Thirdly, embodiments of this application provide a vehicle that includes the steer-by-wire redundant control system described in the second aspect or its embodiments.

[0021] Compared with the prior art, the advantages of the present invention are as follows:

[0022] This invention calculates the target turning radius required based on the steering wheel angle, and then, based on the principle of turning of tracked vehicles (controlling the speed of the steering wheel to be lower than that of the non-steering wheel to achieve the purpose of turning), determines the target ratio of the steering wheel speed to the non-steering wheel speed according to the target turning radius, and finally adjusts the wheel speed accordingly based on the target ratio to achieve steering.

[0023] It can be concluded that when the steer-by-wire system fails to control the steering, the present invention can realize the steering function of the car without relying on the steering components of the steer-by-wire system. At the same time, compared with the redundant technology that relies on hardware backup in the prior art, the present invention will not increase the size and weight of the vehicle, and reduces the cost of use while ensuring that the vehicle has the steering function. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart illustrating the redundancy control method for steer-by-wire in an embodiment of the present invention.

[0026] Figure 2 This is a schematic diagram of the redundant control system for steer-by-wire in an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0029] See Figure 1 As shown in the embodiment of the present invention, the steer-by-wire redundancy control method defines two wheels on one side with the same steering direction as the steering wheel as steering-side wheels, and two wheels on the other side as non-steering-side wheels; for example, when turning left, the left front wheel and left rear wheel are steering-side wheels, and the right front wheel and right rear wheel are non-steering-side wheels. The method includes the following steps: when the steer-by-wire system malfunctions and the vehicle is in a straight-line state, a target ratio of the wheel speed of the steering-side wheel (hereinafter referred to as wheel speed) and the non-steering-side wheel speed is determined according to the steering wheel angle, and the wheel speed of at least one steering-side wheel and / or at least one non-steering-side wheel is adjusted accordingly based on the target ratio.

[0030] It should be noted that when adjusting wheel speed, you only need to adjust one wheel on the same side, and the other wheel on the same side will adjust its speed accordingly. This is not a restriction for four-wheel drive vehicles. To improve vehicle stability, it is better to adjust both wheels on the same side together.

[0031] Therefore, this invention calculates the target turning radius required at the steering wheel angle, and then, based on the principle of turning of tracked vehicles (controlling the speed of the steering wheel to be lower than that of the non-steering wheel to achieve the purpose of turning the vehicle), determines the target ratio of the steering wheel speed and the non-steering wheel speed according to the target turning radius, and finally adjusts the wheel speed of the corresponding wheel according to the target ratio to achieve turning.

[0032] It can be concluded that when the steer-by-wire system fails to control the steering, the present invention can realize the steering function of the car without relying on the steering components of the steer-by-wire system. At the same time, compared with the redundant technology that relies on hardware backup in the prior art, the present invention will not increase the size and weight of the vehicle, and reduces the cost of use while ensuring that the vehicle has the steering function.

[0033] Preferably, the criteria for determining a malfunction in the steer-by-wire system are: δsw i-δ≥δ2, where δ sw δ represents the steering wheel angle, i represents the steering ratio, δ represents the steering wheel angle, and δ2 represents a preset fault threshold. The principle is that if the above formula is met, it indicates no steering response, meaning the steer-by-wire system has malfunctioned and cannot steering. In this case, the redundant steer-by-wire control method needs to be activated. The condition for determining if the vehicle is in a straight-line state is: δ < δ1, where δ1 represents a preset straight-line determination threshold. The reason is that if the vehicle is not in a straight-line state, the target turning radius cannot be accurately calculated.

[0034] Preferably, the process following a malfunction in the steering system via this method specifically includes:

[0035] Deceleration and braking process: When the vehicle speed S is greater than the preset safety upper limit threshold v′, it means that it is limited by the ground adhesion force and is very likely to cause sideslip and loss of control. At this time, braking and deceleration are performed (either by controlling the brake pedal or the wheel brakes) until S = v′.

[0036] Deceleration and Steering Procedure: When S≤v′ (meaning the vehicle speed is sufficient for steering) and the steering wheel is detected to be turning, the target ratio is determined based on the steering wheel angle. It is then determined whether the actual ratio of the steering wheel speed to the non-steering wheel speed is the same as the target ratio. If so, the steering wheel speed and the non-steering wheel speed are simultaneously decelerated. Otherwise, the steering wheel speed is decelerated to control the steering wheel speed to decrease rapidly (at this time, the non-steering wheel speed will decrease relatively slowly) until the actual ratio reaches the target ratio, at which point the deceleration and steering are completed.

[0037] Under normal circumstances, the initial actual ratio of the steering wheel speed to the non-steering wheel speed during the above process will definitely be different from the target ratio. At this time, you can turn according to the steering wheel angle in the above manner.

[0038] It should be noted that the wheel speed is reduced in the above process as follows: if only the steering wheel is turned (which represents coasting deceleration and steering), a preset braking force is applied to the decelerating wheels; if the steering wheel is turned at the same time as the vehicle braking signal (i.e., brake pedal displacement signal), which represents braking deceleration and steering, the braking force corresponding to the vehicle braking signal is applied to the decelerating wheels.

[0039] Preferably, the method further includes the following steps: pre-setting a safety lower limit threshold v″, defining that after S reaches below v″ (i.e., S≤v″) (S below v″ means that the vehicle speed can safely turn, and the present invention aims to turn when the vehicle speed is below v″), there will be no situation where S exceeds v″ (i.e., S>v″); when S≤v″, the acceleration turning process can be performed.

[0040] Accelerated steering process: When S≤v″ and the steering wheel is rotated and the vehicle acceleration signal (accelerator pedal displacement signal) is detected, the target ratio is determined according to the steering wheel angle; under the condition of S≤v″, the actual ratio is made to reach the target ratio by changing the wheel speed on the non-steering side and / or the wheel speed on the steering side, and the accelerated steering is completed at this time.

[0041] It should be noted that, based on the disclosed effects represented by v′ and v″, those skilled in the art can set the specific values ​​of v′ and v″ according to the above requirements and specific vehicle parameters. In this embodiment, the vehicle's wheelbase is 1.7m and the track width is 2.9m. v′ is taken as the vehicle's speed under relatively harsh operating conditions (f = 0.5, a = 0.8m / s). 2 The vehicle speed at the maximum target turning radius of 20m, based on the sideslip conditions: Where f represents the ground adhesion coefficient, g represents gravitational acceleration, and a represents the longitudinal deceleration of the vehicle, the calculated speed v′ = 34 km / h. v″ is taken as the vehicle traveling under extreme conditions (f = 0.2, a = 1 m / s²). 2 The vehicle speed when the maximum target turning radius is 10m can be calculated to be v″=18km / h.

[0042] Preferably, the specific execution steps in the acceleration steering process, which involve changing the wheel speeds v2 on the non-steering side and v1 on the steering side to achieve the target ratio, include: accelerating v2 (i.e., applying acceleration corresponding to the vehicle acceleration signal), then determining whether the actual ratio reaches the target ratio under the condition S≤v″. If yes, the process ends; otherwise, it represents... If the target ratio has not yet been reached, while keeping S from increasing, continue to accelerate v2 while decelerating v1 until the actual ratio reaches the target ratio.

[0043] Preferably, to ensure safety, preventing vehicle skidding is necessary when steering (i.e., preventing skidding has a higher priority than steering); therefore, during the execution of the above acceleration or deceleration steering procedures, if This indicates that the vehicle may be skidding, where f represents the ground adhesion coefficient, g represents gravitational acceleration, and a represents the vehicle's longitudinal deceleration. At this point, the subsequent process is terminated, and the speed difference between v2 and v1 is reduced until...

[0044] The specific way to reduce the speed difference between v2 and v1 is as follows: if v2 is decelerating at this time, stop decelerating v2 and control v1 to decelerate; if v1 is accelerating at this time, stop accelerating v1 and control v2 to decelerate.

[0045] Preferably, in this method, the steering wheel angle δ is used as the basis for the method.sw The formula for calculating the target ratio k of the steering side wheel speed v1 and the non-steering side wheel speed v2 is as follows: Where R represents the target turning radius, B represents the track width (i.e., the distance between two wheels on the same side), and L represents the wheelbase.

[0046] See Figure 2 As shown, the steer-by-wire redundancy control in this embodiment of the invention includes a fault diagnosis unit and a control unit:

[0047] The fault diagnosis unit is used to send a working signal to the control unit when a fault is detected in the steer-by-wire system.

[0048] The control unit is used to execute the above method after receiving a working signal.

[0049] Preferred, see Figure 2 As shown, the system also includes a steering wheel angle sensor, a tire angle sensor, a brake sensor, a wheel speed sensor, and a wheel speed controller.

[0050] The steering wheel angle sensor is used to: collect the steering wheel angle and feed it back to the control unit;

[0051] The tire angle sensor is used to: collect the tire steering angle (mainly the steering wheel steering angle) and feed it back to the control unit;

[0052] The brake sensor is used to: collect vehicle braking signals (brake pedal displacement signals in this embodiment) and feed them back to the control unit;

[0053] Wheel speed sensors are used to: collect wheel speeds on the steering side and non-steering side and feed them back to the control unit.

[0054] The wheel speed controller is used to control the wheel speed on the steering side and the wheel speed on the non-steering side according to the instructions of the control unit (deceleration, acceleration, and speed maintenance). In this embodiment, one wheel speed controller includes a wheel brake (for applying braking force to the wheel) and a motor controller (for controlling the wheel motor to change the wheel speed); one wheel speed controller corresponds to one wheel (that is, each wheel is individually equipped with a wheel speed controller).

[0055] The vehicle in this embodiment of the invention includes the system described above.

[0056] Steering wheel angle sensor and tire angle sensor are used to measure the rotation angle of the steering wheel and tires, and the fault diagnosis unit is used to identify faults in the steer-by-wire system. The brake pedal displacement sensor signal is received by the control unit and used to control the wheel brakes to output corresponding braking force. The wheel brakes and motor controller are used to control the left and right wheels of the vehicle to achieve different target wheel speeds, and the wheel speed sensor is used to feed back wheel speed signals to the control unit. The tire angle sensor is installed on the wheels that normally have steering function. Each wheel is individually equipped with a wheel brake and motor controller, and the wheel brake is an electromechanical braking system.

[0057] Those skilled in the art will understand that all or some of the steps, systems, and apparatuses disclosed above, and their functional modules / units, can be implemented as software, firmware, hardware, or suitable combinations thereof. In hardware implementations, the division between functional modules / units mentioned above does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed collaboratively by several physical components. Some or all physical components may be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit (ASIC). Such software can be distributed on a computer-readable storage medium, which may include computer-readable storage media (or non-transitory media) and communication media (or transient media).

[0058] As is known to those skilled in the art, the term computer-readable storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer-readable storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, it is known to those skilled in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0059] For example, the computer-readable storage medium may be an internal storage unit of the electronic device described in the foregoing embodiments, such as a hard disk or memory of the electronic device. The computer-readable storage medium may also be an external storage device of the electronic device, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, Flash Card, etc., provided on the electronic device.

[0060] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A steer-by-wire redundancy control method, defining two wheels on one side of the same steering direction as steering side wheels, and two wheels on the other side as non-steering side wheels; characterized in that, The method includes the following steps: Determine the target ratio of the wheel speed on the steering side and the wheel speed on the non-steering side based on the steering wheel angle, and adjust at least one wheel speed on the steering side and / or the non-steering side accordingly based on the target ratio; the specific process includes: When the vehicle speed S is greater than a pre-set safety upper threshold value , braking deceleration is performed until S= ; when S≤ , and a steering wheel rotation is monitored, the target ratio is determined according to the steering wheel steering angle; the steering side wheel speed is decelerated until the actual ratio reaches the target ratio; The method also includes the following steps: pre-setting a safety lower limit threshold. S≤ Afterwards, control S cannot be raised to exceed When S≤ Furthermore, when steering wheel rotation and vehicle acceleration signals are detected, the target ratio is determined based on the steering wheel angle; when S≤ Under these conditions, the actual ratio is made to reach the target ratio by changing the wheel speed on the non-steering side and / or the wheel speed on the steering side. The specific process of adjusting the actual ratio to the target ratio by changing the non-steering wheel speed v2 and the steering wheel speed v1 includes: accelerating v2, if S≤ If the target ratio is not reached under the given conditions, while keeping S from increasing, v2 will continue to be accelerated while v1 is decelerated until the actual ratio reaches the target ratio. The method based on the steering wheel angle The formula for calculating the target ratio k of the steering side wheel speed v1 and the non-steering side wheel speed v2 is as follows: , Where R represents the target turning radius, B represents the track width, L represents the wheelbase, and i represents the steering ratio; During the execution of this method, if Then the subsequent process will be suspended and the scope narrowed. and The speed difference until f represents the ground adhesion coefficient, g represents the gravitational acceleration, and a represents the vehicle's longitudinal deceleration.

2. The steer-by-wire redundancy control method as described in claim 1, characterized in that, The triggering condition for this method is: ,and < ,in Represents the steering wheel angle. Represents the steering angle of the steering wheel. This represents a pre-set fault threshold. This represents a pre-set threshold for determining the straight line.

3. A redundant control system for steer-by-wire, characterized in that: The system includes a control unit for: executing the steer-by-wire redundancy control method as described in claim 1 or 2.

4. The steer-by-wire redundant control system as described in claim 3, characterized in that: The system also includes a fault diagnosis unit, a steering wheel angle sensor, a tire angle sensor, a brake sensor, a wheel speed sensor, and a wheel speed controller; The fault diagnosis unit is used to: send a working signal to the control unit when the triggering condition described in claim 2 is detected; The steering wheel angle sensor is used to: collect the steering wheel angle and feed it back to the control unit; The tire angle sensor is used to: collect the tire steering angle and feed it back to the control unit; The brake sensor is used to: collect vehicle braking signals and feed them back to the control unit; Wheel speed sensors are used to: collect wheel speeds on the steering side and non-steering side and feed them back to the control unit; The wheel speed controller is used to control the wheel speed on the steering side and the wheel speed on the non-steering side according to the instructions of the control unit.

5. A vehicle, characterized in that: The vehicle includes the steer-by-wire redundant control system as described in claim 3 or 4.

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