Variable-Velocity Lateral Control for Lane Centering on Curves
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Solution Overview
Problem
Existing lateral control methods for vehicles assume constant longitudinal velocity, leading to degraded performance when vehicles accelerate or decelerate along a road curve, causing oscillation or lane departure.
Innovation Solution
A predictive variable velocity model-based method that determines the vehicle's speed profile and curvature of the road, calculates a variable velocity feedforward control command using the steering angle error, and employs Model Predictive Control to maintain the vehicle centered in the lane by adjusting speed and steering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If lateral control methods assume constant longitudinal velocity, then the control system is simple to implement, but the lane centering control performance degrades when the vehicle accelerates or decelerates
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant-velocity assumption to a dynamic variable-velocity model. The lateral control system now accounts for longitudinal acceleration and deceleration by incorporating velocity derivatives (dv/dt) and curvature changes into the control calculations, allowing the system to adapt to changing vehicle operating conditions while maintaining lane centering performance
Solution Approach 2:
The patent changes the fundamental parameter assumption from constant velocity to variable velocity. By introducing velocity as a time-varying parameter with derivatives (dv/dt) and incorporating curvature (κ) and its rate of change (dκ/dt), the control system accurately models vehicle behavior during acceleration and deceleration maneuvers, resolving the performance degradation issue
2Adaptability or versatility
If the vehicle travels along a road curve at variable speed, then the vehicle can adapt to changing road conditions, but the vehicle starts to oscillate within the lane or depart from the lane
Solution Approach 1:
The patent implements feedback by continuously measuring actual vehicle position, velocity, and acceleration, then comparing these against desired trajectory parameters. The lateral control system uses this feedback to calculate steering corrections that counteract oscillations and maintain stable lane positioning, even when the vehicle accelerates or decelerates on curved roads
Solution Approach 2:
The patent applies preliminary action by predicting future vehicle states based on current velocity, acceleration, and road curvature. The control system proactively adjusts steering before oscillations occur by calculating feedforward control terms that anticipate the vehicle's response to longitudinal acceleration changes, preventing lane departure before it happens
Data Source
AI summary
A method for vehicle lane centering includes determining a speed profile over a predetermined period of time to maintain a predetermined speed while a vehicle moves within a lane of a road. The road has a road curve. The predetermined period of time includes a current time and a future time. The method further includes determining a curvature of a vehicle path along the road curve of the road and determining an error of a steering angle command using the speed profile and the curvature of the vehicle path along the road curve of the road. Further, the method further includes determining a variable velocity feedforward control command using the error on the steering angle command and controlling the vehicle using the variable velocity feedforward control command.