Autonomous Vehicle Stop-Hold Control Using Standstill Feedback
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Solution Overview
Problem
Current autonomous driving systems lack an effective method to maintain a vehicle in a stationary state after receiving a command to stop, leading to potential instability and inappropriate brake hold control.
Innovation Solution
The system sends a first command for deceleration and a second command to maintain stationary, using signals indicating longitudinal velocity and standstill status to ensure continuous deceleration until the vehicle is fully stopped, and then activates the electric parking brake for enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the autonomous driving system continuously issues deceleration commands after the vehicle stops, then the vehicle can be maintained stationary, but unnecessary acceleration requests may occur causing instability
Solution Approach 1:
The autonomous driving system monitors the standstill status signal from the vehicle platform to determine when the vehicle has fully stopped. This feedback mechanism allows the system to adjust its command strategy: continuing deceleration commands during the stopping process, then switching to stationary maintenance commands after stopping, thereby preventing unnecessary acceleration requests and ensuring stable stationary maintenance.
Solution Approach 2:
The system dynamically transitions between two distinct control modes: deceleration mode (when the vehicle is moving) and stationary maintenance mode (when the vehicle has stopped). This dynamic adaptation of control strategy based on real-time vehicle state ensures optimal performance across different operating conditions while maintaining system stability.
2Device complexity
If the autonomous driving system uses only deceleration commands to stop the vehicle, then the stopping function is simple, but the vehicle cannot be reliably maintained stationary after stopping
Solution Approach 1:
The control process is segmented into two distinct phases: the deceleration phase (using first commands) and the stationary maintenance phase (using second commands). This segmentation allows each phase to be optimized independently with appropriate control strategies, ensuring reliable stationary maintenance while keeping the overall system manageable.
Solution Approach 2:
The system performs preliminary deceleration actions using first commands to bring the vehicle to a stop, then transitions to stationary maintenance actions using second commands. This preliminary action ensures the vehicle is properly stopped before initiating the stationary maintenance protocol, thereby improving reliability.
3Speed
If the vehicle platform responds to deceleration commands without considering standstill status, then the control response is fast, but brake hold control cannot be activated appropriately
Solution Approach 1:
The vehicle platform continuously provides feedback on the standstill status signal to the autonomous driving system. This feedback enables the system to determine the appropriate moment to activate brake hold control, ensuring both rapid response and reliable activation under suitable conditions.
Solution Approach 2:
The system prepares for brake hold control activation by continuously monitoring the standstill status signal during the deceleration process. When the vehicle approaches complete stopping, the system is ready to activate brake hold control at the optimal moment, ensuring reliable stationary maintenance.
Data Source
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AI summary
A vehicle (1) comprises an autonomous driving system (200) and a vehicle platform (120) that controls the vehicle in response to a command received from the autonomous driving system. In the present vehicle, when the autonomous driving system issues a first command to request the vehicle platform to provide deceleration to stop the vehicle and a first signal indicates 0 km/h or a prescribed velocity or less, the autonomous driving system issues a second command to request the vehicle platform to maintain stationary. And after brake hold control is finished, a second signal indicates standstill. Until the second signal indicates standstill, the first command continues to request the vehicle platform to provide deceleration.