Coordinated Front Rear Steering for Lane Tracking
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Solution Overview
Problem
Existing vehicle lane tracking systems face challenges in effectively maintaining vehicle position within a lane, especially at slower speeds or in stop-and-go traffic, due to limitations in steering torque and control strategies.
Innovation Solution
A lane tracking system incorporating both front and rear steering controllers, with a processor that determines desired steering angles and torque commands to minimize errors between the vehicle's trajectory and desired course, allowing for adaptive control of both front and rear wheels to maintain lane centering or execute lane changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only front steering control is used, then the system complexity is low, but the lane tracking performance deteriorates at slower speeds and in stop-and-go traffic
Solution Approach 1:
The patent combines front steering control and rear steering control into a unified lane tracking system. The rear steering controller is integrated with the front steering controller, and both work cooperatively under a common control strategy to achieve superior lane tracking performance across all driving conditions, resolving the contradiction between system complexity and reliability.
Solution Approach 2:
The control strategy dynamically adjusts the distribution of steering torque between front and rear wheels based on vehicle speed and driving conditions. At higher speeds, front steering dominates; at lower speeds and in stop-and-go traffic, rear steering is activated to enhance tracking accuracy, making the system adaptive rather than static.
2Reliability
If rear steering controller is added to improve lane tracking at slow speeds, then the lane tracking performance improves, but the device complexity increases
Solution Approach 1:
The rear steering controller is designed to perform multiple functions: enhancing lane tracking at slow speeds, assisting during lane changes, and providing stability control support. This multi-functionality justifies the added complexity by delivering comprehensive performance improvements across various operating conditions rather than solving a single narrow problem.
Solution Approach 2:
The system changes the operational parameters of the steering system by introducing variable rear wheel steering angles and torques based on vehicle speed and lateral position errors. The control strategy adjusts the rear steering gain and torque distribution dynamically, transforming a complex hardware addition into a manageable control problem through parameter optimization.
3Measurement precision
If both front and rear steering torque commands are always active, then the lane tracking accuracy improves, but the steering system responsiveness deteriorates due to torque threshold delays
Solution Approach 1:
The control strategy applies preliminary action by proactively engaging rear steering torque commands in anticipation of front steering torque thresholds being reached. When front steering torque approaches its threshold, the system preemptively activates rear steering assistance, preventing torque saturation and maintaining responsive steering behavior without waiting for the threshold to be exceeded.
Solution Approach 2:
The system implements continuous feedback monitoring of front steering torque magnitude and actively adjusts rear steering torque commands based on this feedback. When front steering torque exceeds predetermined thresholds, the feedback loop triggers rear steering engagement to share the steering burden, maintaining both accuracy and responsiveness through real-time adaptive control.
Data Source
AI summary
A lane tracking system for a vehicle includes a front steering controller, a rear steering controller, and a lane tracking processor. The front steering controller is configured to rotate a front wheel of the vehicle through a front steering angle in response to a front steering torque command, and the rear steering controller is configured to rotate a rear wheel of the vehicle through a rear steering angle in response to a rear steering torque command. The lane tracking processor is configured to determine a desired course of the vehicle along a roadway, estimate a trajectory of the vehicle based on sensed vehicle motion, compute an error between the determined desired course and the estimated trajectory, and provide a front steering torque command to the front steering controller, and a rear steering torque command to the rear steering controller to minimize the computed error.