Vehicle Steering Control Using Lateral Speed for Path Convergence
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Solution Overview
Problem
Existing vehicle steering devices with lane keeping assistance functions fail to effectively converge the vehicle's lateral displacement to a target travel line, particularly due to the lack of consideration for yaw rate and unclear convergence of the travel locus to the target locus.
Innovation Solution
A vehicle steering device that includes a travel path recognition section, a target travel line setting section, a lateral displacement calculation section, and a target steering angle calculation section, which calculates and controls the steering angle based on lateral speed to reduce lateral displacement, thereby converging the vehicle to the target travel line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the control gain is corrected based on curvature by multiplying future lateral deviation, then the control gain is adjusted according to travel path curvature, but the travel locus does not clearly converge to the target locus and lateral displacement is not effectively reduced
Solution Approach 1:
The patent implements feedback control by calculating lateral speed from lateral deviation and using it to determine the target steering angle. The lateral speed is derived from the rate of change of lateral deviation, creating a closed-loop control system that continuously adjusts steering based on current position relative to the target travel line, ensuring reliable convergence.
Solution Approach 2:
The patent changes the control parameter from static curvature-based gain adjustment to dynamic lateral speed-based steering angle calculation. By using lateral speed (the time derivative of lateral deviation) as the control parameter, the system adapts to real-time vehicle position and motion state, enabling effective convergence to the target travel line.
2Device complexity
If yaw rate is not considered in the control calculation, then the control system is simpler, but the vehicle cannot achieve accurate travel along the target travel line
Solution Approach 1:
The patent introduces lateral speed as an intermediary parameter that connects lateral deviation to target steering angle. Instead of directly using complex multi-parameter models, the system uses lateral speed (derived from lateral deviation rate) as a mediator to simplify the control calculation while maintaining accuracy in following the target travel line.
3Measurement precision
If complex multi-parameter control models are used to consider yaw rate and travel locus convergence, then travel accuracy improves, but the control system becomes more complex
Solution Approach 1:
The patent extracts the essential control element from complex multi-parameter models by focusing on lateral speed as the key parameter. Instead of using comprehensive models that include yaw rate, vehicle dynamics, and multiple state variables, the system isolates and utilizes lateral speed to achieve effective and simple control for maintaining accurate travel along the target line.
Data Source
AI summary
Provided are a vehicle steering device and the like, which are capable of converging a lateral displacement at a forward gazing-point distance to a target travel line with simple control. A target travel line for a vehicle to travel by following a travel path recognized from an image taken by a camera or the like is set. A lateral speed, which is a change amount of the lateral displacement that is a difference between a position of the target travel line at the forward gazing-point distance and a position of the vehicle, is controlled so that the lateral displacement is reduced. A target steering angle is calculated based on the lateral speed, and a steering angle of the vehicle is controlled based on the calculated target steering angle.