Emergency Braking Override for Vehicle Skid Avoidance
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Solution Overview
Problem
Autonomous emergency braking systems fail to properly adjust braking controls due to lack of feedback during skidding, leading to improper deceleration and potential loss of traction, especially on slippery road conditions.
Innovation Solution
A second braking control algorithm overrides the original algorithm to recalibrate braking pressure, prioritizing reduction of the discrepancy between vehicle velocity and wheel speed to prevent skidding and ensure safe deceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the original braking control algorithm is used during emergency braking, then high deceleration can be achieved, but skidding occurs due to unrealistic braking pressure values when traction is limited
Solution Approach 1:
The system dynamically switches between two braking control algorithms based on detected skidding conditions. When skidding is detected through velocity-discrepancy monitoring, the system transitions from the first algorithm (optimized for high deceleration) to the second algorithm (optimized for skid prevention), enabling adaptive control that responds to changing traction conditions
Solution Approach 2:
The system changes the control parameters by switching algorithms that calculate braking pressure differently. The second algorithm modifies the braking pressure calculation to account for traction limitations during skidding, generating realistic pressure values that prevent wheel lockup while maintaining effective deceleration
2Reliability
If anti-lock braking mechanisms are activated during skidding, then wheel lockup is prevented, but the ADV cannot properly determine braking controls due to lack of feedback
Solution Approach 1:
The system uses velocity-discrepancy feedback to detect skidding conditions by comparing the difference between the vehicle's actual velocity and the wheels' rotational speed. This feedback mechanism enables the system to identify when skidding is occurring and trigger the appropriate algorithm switch, compensating for the lack of feedback during ABS activation
Solution Approach 2:
The velocity-discrepancy measurement acts as an intermediary indicator that provides indirect feedback about skidding conditions. Instead of relying on direct feedback from the ABS system, the system uses this intermediary measurement to infer traction status and control the braking algorithm selection
3Reliability
If braking pressure is increased to achieve desired deceleration, then collision prevention is improved, but skidding is exacerbated on slippery road conditions
Solution Approach 1:
The system dynamically adjusts braking pressure characteristics by switching algorithms based on real-time skid detection. The first algorithm applies aggressive braking for collision avoidance, while the second algorithm applies moderated braking pressure when skidding is detected, creating a dynamic response that balances collision prevention with skid avoidance
Solution Approach 2:
The system takes preliminary anti-action by detecting skidding conditions in advance and switching to the second algorithm before severe skidding occurs. This preventive switching stops the harmful effect of excessive braking pressure before it can fully develop, maintaining traction while still achieving effective deceleration
Data Source
AI summary
This disclosure provides systems and methods for deceleration control during emergency braking using control algorithm override. An embodiment of the present disclosure provides a computer-implemented method for deceleration by a controlling device of an autonomous driving vehicle (ADV). The method includes engaging a braking system of the ADV to decelerate the ADV using a first deceleration algorithm. When an onset of discrepancy between a velocity of the ADV and a corresponding wheel speed of the ADV is detected, a processing device, based on the discrepancy, overrides an output of the first deceleration algorithm using a second deceleration algorithm that prioritizes in reducing the discrepancy between the velocity of the ADV and the corresponding wheel speed of the ADV over a target rate of deceleration computed by the first deceleration algorithm.