Vehicle Motion Arbitration for Steering Failure Lateral Control
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Solution Overview
Problem
Existing vehicle control devices fail to appropriately control lateral movement when the steering actuator cannot be controlled due to failures or maximum steering angle limitations, leading to unpredictable vehicle behavior.
Innovation Solution
A vehicle control device with an arbitration unit that acquires and arbitrates between steering angle and yaw rate commands from driving support applications, allowing the arbitration unit to instruct either the steering actuator, brake actuator, or drive actuator to achieve desired lateral movement, even if the steering actuator is not functioning properly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only the steering actuator is used to control lateral movement, then the control system is simple, but the system becomes unreliable when the steering actuator fails or reaches maximum steering angle
Solution Approach 1:
The brake actuator and drive actuator are given additional functions beyond their primary purposes. The brake actuator can generate lateral movement through differential braking, and the drive actuator can generate lateral movement through differential wheel torque. This multi-functionality allows the system to achieve lateral movement control through multiple actuators, improving reliability when the steering actuator fails or reaches its limits.
Solution Approach 2:
The arbitration unit dynamically changes the control parameters by selecting different actuators based on the current system state. When the steering actuator is normal, it uses steering angle commands. When the steering actuator fails or reaches maximum angle, the system switches to using brake actuator or drive actuator commands. This parameter change approach allows the system to adapt to different operating conditions and maintain reliability.
2Reliability
If the arbitration unit switches to brake or drive actuators when steering actuator cannot achieve the command, then lateral movement control is maintained, but the response time may increase
Solution Approach 1:
The arbitration unit continuously monitors the state of the steering actuator and pre-evaluates whether the steering actuator can achieve the commanded steering angle. By having the capability to switch to brake or drive actuators ready in advance, the system can quickly transition when needed, minimizing the loss of time. The arbitration unit maintains readiness to use alternative actuators, so when a switch is necessary, the transition is rapid.
3Adaptability or versatility
If the system uses multiple actuators for lateral movement control, then the adaptability to different failure modes is improved, but the control logic becomes more complex
Solution Approach 1:
The arbitration unit divides the control decision-making into distinct segments or modules. It separately evaluates the steering angle command, checks the capability of the steering actuator, and independently determines whether to switch to brake or drive actuators. This segmentation of the arbitration logic makes the complex control system more manageable and easier to implement, while still maintaining high adaptability to different failure modes.
Data Source
AI summary
The vehicle control device includes an arbitration unit configured to arbitrate between a plurality of control commands acquired from a plurality of driving support applications that respectively implements driving support functions, configured to output instructions based on a control command after arbitration to a first control unit that is able to control a steering actuator and a second control unit that is able to control at least one of a brake actuator or a drive actuator, and configured to acquire a steering angle and a yaw rate as the control commands from the driving support applications.