Lane-Keeping Steering Profile for Faster Lateral Speed Convergence
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Solution Overview
Problem
Existing lane departure prevention control devices require a long period to converge the lateral speed of a vehicle to a target lateral speed during lane departure prevention control.
Innovation Solution
A drive assist device with a steering device, sensors, and a processor that performs steering assist by controlling the steering angle to follow a specific steering angle profile, comprising a first and second profile that are continuous with each other, with controlled rates of change and steering angles to achieve rapid convergence of lateral speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lane departure prevention control is used, then lane departure is prevented, but lateral speed convergence takes a long period
Solution Approach 1:
The steering angle profile is segmented into multiple sections (first steering angle profile and second steering angle profile) with different control characteristics. The first profile handles initial lane departure avoidance while the second profile handles lateral speed convergence, allowing each segment to be optimized for its specific function rather than using a single uniform control strategy.
Solution Approach 2:
The control system dynamically switches between different steering angle profiles based on the vehicle's lateral speed and position. The processor determines which profile to apply by evaluating real-time vehicle state, enabling adaptive control that optimizes both lane departure prevention and convergence speed according to current conditions.
2Speed
If steering angle changes rapidly to avoid lane departure, then lane departure is prevented quickly, but occupant discomfort increases
Solution Approach 1:
Different sections of the steering angle profile have different quality characteristics. The first steering angle profile section is designed with smoother transitions to minimize occupant discomfort during initial correction, while the second section is optimized for faster convergence. This local differentiation of control characteristics allows simultaneous optimization of comfort and effectiveness in different phases of the control process.
Solution Approach 2:
The steering angle profile incorporates cushioning transitions by setting the rate of change of steering angle to zero at critical points (initial time and end of steering in each profile section). This beforehand cushioning prevents abrupt steering movements that would cause occupant discomfort while still achieving rapid overall convergence.
3Object-affected harmful factors
If steering angle rate of change is set to zero at all times, then occupant comfort is maximized, but lane departure prevention response is too slow
Solution Approach 1:
The control system applies periodic action by using two distinct steering angle profiles in sequence. The first profile applies controlled steering input to initiate lane departure avoidance, then the second profile applies corrective steering to converge lateral speed. This periodic switching between different control actions achieves both rapid response and comfort by distributing the steering demand across time rather than applying it all at once.
Data Source
AI summary
The steering angle is controlled according to a steering angle profile. The steering angle profile is composed of a first steering angle profile that causes the vehicle toward the lane departure direction to be directed toward the lane departure avoidance direction, and a second steering angle profile that is continuous with the first steering angle profile, and the rate of change of the steering angle at the initial steering time in the first steering angle profile, the rate of change of the steering angle and the steering angle at the end of steering in the first steering angle profile, the rate of change of the steering angle and the steering angle at the initial steering time in the second steering angle profile, and the rate of change of the steering angle and the steering angle at the end of steering in the second steering angle profile are set to zero.