Autonomous Braking Path Control via Friction Ellipse and Yaw Moment
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Solution Overview
Problem
Existing vehicle control systems during autonomous braking are reactive and fail to effectively maintain the vehicle on the intended path, especially during sliding and skidding situations, leading to diminished velocity reduction.
Innovation Solution
A travel path control method that calculates a friction ellipse and determines a compensating yaw moment to correct the vehicle's path error by comparing the actual and intended paths, transmitting commands to the braking and steering systems based on maximum available acceleration and yaw moment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If autonomous braking is applied during vehicle travel, then velocity reduction is achieved, but the vehicle may depart from the intended path due to lateral instability
Solution Approach 1:
The system calculates a compensating yaw moment in advance to counteract the expected path deviation caused by autonomous braking. This preliminary counter-action prevents the vehicle from departing its intended path while maintaining effective velocity reduction during braking maneuvers.
Solution Approach 2:
The controller proactively determines the necessary compensating yaw moment before significant path deviation occurs. By calculating and applying the compensating moment in advance based on predicted braking effects, the system maintains path stability while achieving velocity reduction.
2Stability of the object's composition
If compensating yaw moment is applied to maintain intended path, then path accuracy is improved, but velocity reduction effectiveness is diminished
Solution Approach 1:
The system dynamically adjusts the magnitude of the compensating yaw moment based on real-time vehicle state parameters and braking conditions. By optimizing the compensating moment parameter, the system achieves sufficient path accuracy while minimizing the impact on velocity reduction effectiveness.
Solution Approach 2:
The controller applies a compensating yaw moment that is sufficient to maintain path accuracy but not excessive to the point of significantly reducing braking effectiveness. This partial action approach balances path maintenance with velocity reduction by applying only the necessary corrective moment.
3Device complexity
If reactive control is used during braking, then system complexity is reduced, but path correction capability is insufficient during sliding and skidding
Solution Approach 1:
The system calculates the compensating yaw moment in advance based on predicted braking effects and vehicle dynamics, rather than reacting after path deviation occurs. This preliminary calculation approach provides reliable path correction during sliding and skidding conditions while maintaining relatively simple control system architecture.
Data Source
AI summary
Methods, systems are provided for controlling a travel path of a vehicle. The method includes the steps of detecting a braking of the vehicle by a computing device, calculating a friction ellipse for the vehicle based on the current state of the vehicle, defecting an intended travel path of the vehicle, detecting an actual travel path of the motor vehicle during the braking and determining if there is a path error where the actual travel path is outside the intended travel path when the braking is detected. When the actual travel path is outside the intended travel path then the method calculates a prospective friction ellipse for the vehicle, determines a compensating yaw moment to correct the path error, determines a maximum acceleration based on the prospective friction ellipse, and transmits a command to the autonomous braking system based on the maximum acceleration and the compensating yaw moment.