Vehicle Steering Control Using Dynamic Reference Points on Curves
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Solution Overview
Problem
Existing vehicle control systems face challenges in maintaining the actual travel trajectory close to the target trajectory, especially when entering and exiting curves, leading to deviations and steering fluctuations, which are not adequately addressed by current automatic drive technologies.
Innovation Solution
A vehicle control apparatus that sets a first reference point before an inflection point and a second reference point after it, adjusting the target steering angle based on the curvature of the arc passing through the current position and these points, ensuring the second distance from the vehicle to the second reference point is longer than the first distance to the first reference point under identical travel conditions, thereby reducing deviations and fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed reference point setting method is used for curve navigation, then the control algorithm is simple, but the vehicle trajectory deviates from the target trajectory and steering fluctuations occur
Solution Approach 1:
The reference point distance is made dynamic rather than fixed. The system automatically adjusts the reference point distance based on the curvature of the target trajectory, using a longer distance for low curvature (gentle curves) and a shorter distance for high curvature (sharp curves). This dynamic adjustment resolves the contradiction by adapting the control parameters to match the actual road conditions, thereby improving trajectory accuracy without requiring overly complex fixed algorithms.
Solution Approach 2:
The system changes the parameter of reference point distance based on the curvature parameter of the target trajectory. By calculating the curvature at different positions and adjusting the reference point distance accordingly, the system optimizes the control algorithm's performance for varying curve conditions, achieving both reasonable complexity and high trajectory accuracy.
2Speed
If the reference point is set closer to the vehicle, then the response to sharp curves is faster, but the trajectory deviation increases on gentle curves
Solution Approach 1:
The reference point distance is dynamically adjusted based on the detected curvature of the target trajectory. For sharp curves with high curvature values, the system sets a shorter reference point distance to enable faster steering response. For gentle curves with low curvature values, the system sets a longer reference point distance to maintain accurate trajectory following. This dynamic adaptation resolves the contradiction between response speed and trajectory accuracy.
Solution Approach 2:
The system applies different reference point distances for different local conditions of the road geometry. Instead of using a uniform reference point distance for all curves, the system tailors the reference point distance to the specific curvature characteristics of each segment of the target trajectory, optimizing performance for each local condition.
3Manufacturing precision
If the reference point distance varies with curvature, then the trajectory accuracy improves, but the control system complexity increases
Solution Approach 1:
The system changes the reference point distance parameter based on the curvature parameter of the target trajectory. By establishing a clear relationship between curvature and reference point distance, the system achieves improved trajectory accuracy through parameter adaptation while keeping the control logic relatively straightforward.
Solution Approach 2:
The system calculates the curvature of the target trajectory at the current position and uses this feedback information to determine the appropriate reference point distance. This feedback mechanism allows the system to automatically adapt to varying curve conditions, improving trajectory accuracy without requiring manual intervention or overly complex control structures.
Data Source
AI summary
A vehicle control apparatus includes a processor. Before the vehicle passes through an inflection point of a curvature of a target trajectory, the processor sets a first reference point before the inflection point. After the vehicle passes through the inflection point, the processor sets a second reference point at a position where a second distance from a current position of the vehicle after the vehicle passes through the inflection point to the second reference point is longer than a first distance from a current position of the vehicle before the vehicle passes through the inflection point to the first reference point when compared under travel conditions identical in a vehicle speed, an acceleration rate, a deceleration rate, or a steering angle. The processor sets a target steering angle based on the curvature of an arc passing through the current position and the first reference point or the second reference point.