Autonomous Vehicle Steering Control for Transient Emergency Handling
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Solution Overview
Problem
Conventional methods for analyzing vehicle motion, particularly during cornering, are limited in detecting transient conditions and predicting upcoming changes, as they rely on steady state or frequency domain analysis, which do not account for time history or driver perception, and are inadequate for autonomous vehicles and SBW-equipped vehicles.
Innovation Solution
A method and system for steer control that detects lateral velocities, yaw rates, and side slip angles, calculating target steer angles to align wheels with the vehicle's track angle, and adjusts the current steer angle based on these calculations to improve stability and feedback to the driver, especially in emergency situations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional transient motion analysis methods are used to evaluate vehicle characteristics during maneuvers, then vehicle cornering and feedback to driver can be studied, but the methods cannot accurately detect transient conditions or predict upcoming changes in vehicle motion
Solution Approach 1:
The system performs preliminary calculations of yaw rate, side slip angle, and track angle before emergency steering actions are needed. By continuously monitoring and pre-calculating these motion parameters, the system prepares predictive information about upcoming vehicle behavior changes, enabling proactive control adjustments rather than reactive responses.
Solution Approach 2:
The system implements continuous feedback by monitoring lateral velocities at multiple points, calculating yaw rates, and determining side slip angles in real-time. This feedback loop provides ongoing information about transient motion conditions, allowing the control system to detect changes as they occur and predict future vehicle states for improved stability control.
2Device complexity
If steady state or frequency domain analysis is used, then analysis simplicity is maintained, but time history and driver perception cannot be accounted for
Solution Approach 1:
The system segments the complex vehicle motion analysis into distinct calculable components: lateral velocity measurement at front and rear points, yaw rate calculation from velocity differences, side slip angle determination, and track angle computation. This segmentation transforms an otherwise intractable complex analysis into manageable sequential calculations that preserve time history information.
Solution Approach 2:
The system transitions from static steady-state analysis to dynamic transient analysis by continuously calculating motion parameters over time. The method captures time-varying characteristics of vehicle cornering through real-time measurement and calculation of lateral velocities, yaw rates, and angles, enabling analysis of actual driving dynamics rather than idealized steady conditions.
3Ease of operation
If conventional steer control is used in autonomous vehicles, then basic steering functions are maintained, but stability and path determination are inadequate in emergency situations
Solution Approach 1:
The system introduces track angle as an intermediary parameter that mediates between conventional steering inputs and actual vehicle response during emergency maneuvers. By calculating and utilizing track angle—the angle between the vehicle's longitudinal axis and its actual path of motion—the system bridges the gap between intended steering actions and actual vehicle behavior, improving path determination accuracy and stability control.
Data Source
AI summary
A method is provided for steering control of a vehicle by using lateral velocity of two know points (or lateral velocity of one known point and yaw rate), longitudinal velocity and steer angle information. These factors are used to calculate a target steer angle based on the track angle based on yaw decomposition to thus adjust a current steer angle of the vehicle based on the target steer angle.