A method for active safety control of a steer-by-wire system

Abstract

The application discloses a kind of active safety control method of steer-by-wire system, belong to active safety control technical field.This method is based on steer-by-wire system, brake-by-wire system and sensing system, obtains road edge information by sensing system, if the direction of vehicle travel points to road edge, the time of vehicle reaches road edge is calculated in combination with current speed, if the time is less than first time threshold simultaneously driver is identified without steering operation, then through early warning mechanism reminds driver to operate steering in time;If the time is less than second time threshold, then by steering motor actively applies torque to control vehicle driving direction to return to parallel with road direction, if driver operates steering wheel at this time has not been identified and brake pedal signal, accelerator pedal signal continues without change, then actively applies brake and gently controls vehicle to stop.The scene targeted by the application is more certain, the technology is more simple and effective and easy to implement, and the function can be realized only by using the existing sensor data of vehicle.

Description

Technical Field

[0001] The present invention relates to the technical field of active safety control, and more specifically to an active safety control method for a steer-by-wire system. Background Art

[0002] In recent years, with the rapid development of steer-by-wire and assisted driving technologies, improving vehicle safety through active safety control based on these technologies has become a hot topic of research within the industry. Steer-by-wire technology uses an electric motor to achieve steering wheel angle control and torque overlay control. Corresponding assisted driving technologies include lane centering and lane keeping functions. However, these functions are merely driver assistance features, enabled or disabled by the driver, and are not automatically activated to protect the vehicle and passengers in emergency situations. However, dangerous situations often occur where drivers lose control of the steering wheel due to fatigue, distraction, or sudden illness, causing the vehicle to veer off the road.

[0003] Application Publication No. CN 109677404A discloses an active safety assistance device and method for vehicles that utilize vehicle-road collaboration based on driving behavior. The device collects real-time images of the driver's face, driving movements, and road conditions. Based on trained fatigue and driving behavior models, it determines whether the driver is fatigued or driving in violation of regulations. It then analyzes the road conditions and driver status to derive a corresponding active safety control strategy, controlling the onboard active assistance module to provide the appropriate driving assistance. The patent first detects the driver's fatigue state and driving behavior. If an anomaly is detected and the vehicle deviates from its current lane, the system activates the steering system to correct the deviation.

[0004] The above patent determines whether a vehicle has departed from its lane by identifying lane markings. This method is not suitable for identifying road edges. It also requires additional driver monitoring equipment, increasing costs. It also requires analyzing the driver's facial image, placing higher demands on the system's chip processing capabilities. Furthermore, the above patent does not account for the possibility of false triggering of functions. If the active safety assistance system is falsely triggered, it can interfere with the driver's steering operation and even conflict with the driver's control, posing a significant safety hazard.

[0005] Therefore, how to build an active safety control method through wire-controlled steering that can proactively intervene to ensure the safety of the vehicle and passengers in scenarios where the driver is distracted or loses control of the steering wheel due to physical abnormalities is a direction worth exploring. Summary of the Invention

[0006] The present invention provides an active safety control method for a steer-by-wire system, which aims to solve the problem that the driver loses control of the steering wheel due to distraction or physical abnormality, causing the vehicle to run off the road or collide with an obstacle at the edge of the road.

[0007] The present invention adopts the following technical solutions:

[0008] A method for active safety control of a steer-by-wire system is based on several subsystems, including a steer-by-wire system, a brake-by-wire system, and a perception system. The steer-by-wire system implements a warning mechanism and an active steering intervention mechanism, receiving accelerator pedal position signals, brake pedal position signals, vehicle speed signals, and steering wheel torque signals. The brake-by-wire system does not require mechanical decoupling and only needs to be able to respond to external control commands. The perception system provides road edge information. Specific steps are as follows:

[0009] (1) When the vehicle is driving, the perception system identifies the road edge information in real time. The road edge information includes the minimum distance between the vehicle body edge and the road edge, and the angle between the vehicle's driving direction and the road edge.

[0010] (2) Using the road edge information obtained in step (1) and the current vehicle speed information, calculate the time t when the vehicle body edge reaches the road edge;

[0011] (3) When it is recognized that the steering wheel torque signal is less than the torque threshold and the duration is greater than the first duration threshold t l1 , it is considered that the driver has not operated the steering, and it is necessary to monitor the vehicle's tendency to move toward the edge of the road: if the time t calculated in step 2 for the vehicle body edge to reach the road edge is less than the first time threshold t1, the warning mechanism is activated to remind the driver to take over the vehicle's steering control in time; if the steering wheel torque signal is again greater than the torque threshold at this time, it is determined that the driver has resumed steering control and the warning mechanism is exited;

[0012] (4) When the warning mechanism in step 3 is activated, but the driver's steering action is still not received, and the time t for the vehicle body edge to reach the road edge calculated in step 2 is less than the second time threshold t2, it is determined that the vehicle is about to reach the road edge, and the steer-by-wire system activates the active steering intervention mechanism to restore the vehicle to its normal driving direction;

[0013] (5) The vehicle resumes driving parallel to the road direction. During the whole process, the driver's steering action is still not received. At the same time, the driver's actions on the accelerator and brake pedals are recognized. If the duration of no change in the accelerator and brake pedal signals exceeds the second duration threshold t l2 , the safe parking mechanism is triggered, and the wire-controlled steering system requests braking from the wire-controlled brake system to control the vehicle to stop smoothly.

[0014] In a preferred embodiment, in the above step (2), the minimum distance between the edge of the vehicle body and the edge of the road is set to S, and the angle between the vehicle's driving direction and the edge of the road is α; the current vehicle speed is V, then Vsinα is the speed component of the vehicle perpendicular to the edge of the road, and the time it takes for the edge of the vehicle body to reach the edge of the road is t=S / (Vsinα).

[0015] In a preferred embodiment, the method of reminding the driver in step (3) includes controlling the steering motor to vibrate the steering wheel to remind the driver, and requesting an audible and visual alarm from the vehicle instrument.

[0016] In a preferred embodiment, in the above step (5), if the driver's operation of the steering wheel, accelerator pedal, and brake pedal is identified during the smooth parking process, the safe parking mechanism is exited.

[0017] In a preferred embodiment, the above-mentioned driver can actively choose to turn off the early warning mechanism, but the active steering intervention mechanism and the safe parking mechanism cannot be turned off. At the same time, the active steering intervention mechanism and the safe parking mechanism are only allowed to be triggered once during a single driving process.

[0018] In a preferred embodiment, the above-mentioned warning mechanism, active steering intervention mechanism and safe parking mechanism are only allowed to be triggered when the vehicle speed is higher than the vehicle speed threshold V1.

[0019] It can be seen from the above description of the present invention that, compared with the prior art, the present invention has the following advantages:

[0020] 1. The present invention addresses scenarios where the driver loses control of the steering wheel due to distraction or physical abnormalities. To prevent the vehicle from running off the road or colliding with obstacles, the system uses a sensing system to acquire road edge information. If the vehicle's direction of travel points toward the road edge, the time it takes for the vehicle to reach the road edge is calculated based on the angle between the vehicle's direction of travel and the road's direction, the distance between the vehicle and the road edge, and the vehicle's speed. If this time is less than a first time threshold and the driver's lack of steering input is detected through steering wheel force, an early warning mechanism alerts the driver to promptly steer. If this time is less than a second time threshold, the steering motor actively applies torque to control the vehicle's direction of travel back to parallel with the road. If no driver steering input is detected at this point and the brake and accelerator pedal signals remain unchanged, the vehicle's braking is actively applied to bring the vehicle to a smooth stop. The present invention targets more specific scenarios and serves only as a safeguard to prevent vehicles from running off the road, without causing excessive interference to vehicles normally traveling on the road. The technology is more concise, effective, and easy to implement, requiring no additional driver monitoring equipment and relying solely on the vehicle's existing sensor data.

[0021] 2. The present invention includes three mechanisms: an early warning mechanism, an active steering intervention mechanism, and a safe parking mechanism. At the same time, it clarifies the exit conditions after the function is triggered to ensure that the driver can take over the vehicle in time, and prevent the active safety function of the present invention from being accidentally triggered or excessively interfering with the driver's driving behavior. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 2 is a system block diagram of an embodiment of the present invention.

[0023] Figure 2 Flowchart of an embodiment of the present invention. DETAILED DESCRIPTION

[0024] Refer to the following Figure 1 The following describes specific embodiments of the present invention. Numerous details are provided below to provide a comprehensive understanding of the present invention, but those skilled in the art will appreciate that the present invention can be implemented without these details. Well-known components, methods, and processes are not described in detail below.

[0025] This embodiment provides a method for active safety control of a wire-controlled steering system, based on several subsystems, Figure 1 , including a steer-by-wire system, a brake-by-wire system, a perception system, and an instrumentation system. The steer-by-wire system implements early warning mechanisms and active steering intervention mechanisms, receiving signals such as accelerator pedal position, brake pedal position, vehicle speed, and steering wheel torque. The brake-by-wire system requires no mechanical decoupling and only needs to be able to respond to external control commands. The perception system provides road edge information, including lane markings or curbs, while the instrumentation system provides audible and visual warnings.

[0026] Reference Figure 2 The active safety control method of the present invention specifically includes the following steps:

[0027] Step 1: While the vehicle is driving, the perception system identifies road edge information in real time. Road edge information includes the minimum distance between the vehicle body edge and the road edge, and the angle between the vehicle's direction of travel and the road edge.

[0028] Step 2: Using the road edge information obtained in step 1 and the current vehicle speed information, calculate the time t when the edge of the vehicle reaches the road edge.

[0029] Assume the minimum distance between the vehicle's edge and the road's edge is S, and the angle between the vehicle's direction of travel and the road's edge is α. Given the current vehicle speed is V, Vsinα is the component of the vehicle's velocity perpendicular to the road's edge. The time it takes for the vehicle's edge to reach the road's edge is t = S / (Vsinα).

[0030] Step 3: When it is recognized that the steering wheel torque signal is less than the torque threshold and the duration is greater than the first duration threshold tl1 , it is considered that the driver has not operated the steering and the vehicle needs to be monitored for the tendency to move toward the edge of the road.

[0031] If the time t calculated in step 2 above, when the vehicle's edge reaches the road edge, is less than the first time threshold t1, a warning mechanism is activated to alert the driver to promptly take over steering control of the vehicle. This warning mechanism includes controlling the steering motor to vibrate the steering wheel and requesting an audible and visual alarm from the vehicle's instrument cluster. If the steering wheel torque signal is again greater than the torque threshold, the driver is deemed to have resumed steering control and the warning mechanism is terminated.

[0032] Step 4: After the warning mechanism of step 3 is activated, if no steering action by the driver is received, and the time t calculated in step 2 for the edge of the vehicle body to reach the edge of the road is less than the second time threshold t2, it is determined that the vehicle is about to reach the edge of the road. At this time, the steer-by-wire system needs to activate the active steering intervention mechanism to restore the vehicle to its normal driving direction.

[0033] The active steering intervention mechanism described above involves the steer-by-wire system actively applying steering torque via the steering motor to control the vehicle's direction. The control target is to maintain an angle α = 0 between the vehicle's direction of travel and the edge of the road, essentially keeping the vehicle's direction parallel to the road. At this point, the vehicle avoids contact with the edge of the road. If the active steering intervention mechanism detects a steering wheel torque signal greater than a threshold during operation, the driver is deemed to have resumed steering control, and the intervention mechanism is discontinued.

[0034] Step 5: When the intervention mechanism of step 4 is implemented and the vehicle resumes its parallel driving direction, if the driver's steering action is still not received during the whole process, it is judged that the driver is no longer distracted, but is likely to have a sudden illness or other reasons, resulting in the inability to control the vehicle. At this time, in order to prevent misidentification, the system will simultaneously identify the driver's actions on the accelerator and brake pedals. If the duration of no change in the accelerator and brake pedal signals exceeds the second duration threshold t l2 , the safe stop mechanism is triggered. At this time, the steer-by-wire system requests the brake-by-wire system to brake and bring the vehicle to a smooth stop. If the driver's operation of the steering wheel, accelerator pedal, or brake pedal is detected during the smooth stop process, the safe stop mechanism is exited.

[0035] To avoid excessive driver intervention and the risk of misidentification, the driver can choose to disable the system's warning mechanism. However, the active steering intervention and safety stop mechanisms cannot be disabled. Furthermore, these mechanisms are only triggered once during a single driving session. Furthermore, to prevent interference with driver operation in scenarios such as pulling over to the roadside at a low speed or driving onto a curb, the warning mechanism, active steering intervention, and safety stop mechanisms are triggered only when the vehicle speed exceeds the speed threshold V1.

[0036] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A method for active safety control of a steer-by-wire system, characterized in that: Based on several subsystems, including a steer-by-wire system, a brake-by-wire system, and a perception system, the steer-by-wire system implements a warning mechanism and an active steering intervention mechanism, receiving signals such as the accelerator pedal position, the brake pedal position, the vehicle speed, and the steering wheel torque. The driver can actively choose to disable the warning mechanism, but the active steering intervention mechanism and the safe stop mechanism cannot be disabled. At the same time, the active steering intervention mechanism and the safe stop mechanism are only allowed to be triggered once during a single driving process. The brake-by-wire system does not require mechanical decoupling and only needs to be able to respond to external control commands. The perception system provides road edge information. The specific steps are as follows: (1) When the vehicle is driving, the perception system identifies the road edge information in real time. The road edge information includes the minimum distance between the vehicle body edge and the road edge, and the angle between the vehicle's driving direction and the road edge. (2) Using the road edge information obtained in step (1) and the current vehicle speed information, calculate the time t when the vehicle body edge reaches the road edge; (3) When it is recognized that the steering wheel torque signal is less than the torque threshold and the duration is greater than the first duration threshold t l1 , it is considered that the driver has not operated the steering, and it is necessary to monitor the trend of the vehicle moving towards the edge of the road: if the time t calculated in step 2 for the edge of the vehicle to reach the edge of the road is less than the first time threshold t1, the early warning mechanism is activated to remind the driver to take over the steering control of the vehicle in time; If the steering wheel torque signal is again greater than the torque threshold at this time, it is determined that the driver has resumed steering control and the warning mechanism is exited; (4) When the warning mechanism in step 3 is activated, but the driver's steering action is still not received, and the time t for the vehicle body edge to reach the road edge calculated in step 2 is less than the second time threshold t2, it is determined that the vehicle is about to reach the road edge, and the steer-by-wire system activates the active steering intervention mechanism to restore the vehicle to its normal driving direction; (5) The vehicle resumes driving parallel to the road direction. During the whole process, the driver's steering action is still not received. At the same time, the driver's actions on the accelerator and brake pedals are recognized. If the duration of no change in the accelerator and brake pedal signals exceeds the second duration threshold t l2 , the safe parking mechanism is triggered, and the wire-controlled steering system requests braking from the wire-controlled brake system to control the vehicle to stop smoothly.

2. The active safety control method for a steer-by-wire system according to claim 1, wherein: In step (2), the minimum distance between the vehicle body edge and the road edge is set to S, and the angle between the vehicle's driving direction and the road edge is α; the current vehicle speed is V, then Vsinα is the component of the vehicle's speed perpendicular to the road edge, and the time it takes for the vehicle body edge to reach the road edge is t=S / (Vsinα).

3. The active safety control method for a steer-by-wire system according to claim 1, wherein: The method of reminding the driver in step (3) includes controlling the steering motor to vibrate the steering wheel to remind the driver, and requesting the vehicle instrument to send an audible and visual alarm.

4. The active safety control method for a steer-by-wire system according to claim 1, wherein: In step (5), if the driver's operation of the steering wheel, accelerator pedal, and brake pedal is recognized during the smooth parking process, the safe parking mechanism is exited.

5. The active safety control method for a steer-by-wire system according to claim 1, wherein: The warning mechanism, the active steering intervention mechanism and the safe parking mechanism are all allowed to be triggered only when the vehicle speed is higher than the vehicle speed threshold V1.

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