Vehicle Guide Line Projection Using Clothoid Curves
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Solution Overview
Problem
Current systems for projecting guide lines onto a road surface to assist drivers in staying in their lane can lead to oversteering due to perspective effects causing the transition from a straight line to a curve to appear more abrupt than it actually is, resulting in inaccurate steering angle perception.
Innovation Solution
A method that calculates an anticipated travel path for a vehicle based on speed and steering angle, projecting a guide line that initially follows a first clothoid segment when starting a curve and a second clothoid segment when completing it, reducing the abruptness of the transition and improving visibility for the driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a straight line transitions directly into an arc segment in the guide line, then the guide line accurately represents the anticipated travel path, but the driver perceives an abrupt transition due to perspective effects, leading to oversteering
Solution Approach 1:
The patent applies curvature to the guide line by using a clothoid curve instead of a simple arc segment. The clothoid curve has continuously varying curvature that starts at zero and increases gradually, matching the natural transition of the vehicle into a curve. This eliminates the abrupt kink perceived by the driver while still accurately representing the anticipated travel path, thereby resolving the contradiction between measurement precision and driver misperception.
2Object-affected harmful factors
If the guide line follows a clothoid curve from the beginning, then the transition appears smooth to the driver, but the guide line does not accurately represent the vehicle's actual travel path which has an abrupt steering change
Solution Approach 1:
The patent segments the guide line into multiple parts: an initial straight segment, followed by a clothoid curve segment, and then an arc segment. This segmentation allows different portions of the guide line to serve different functions - the straight segment represents the initial path, the clothoid provides smooth visual transition, and the arc segment accurately represents the established curved path. This resolves the contradiction by combining multiple geometric forms to satisfy both accuracy and perceptual smoothness requirements.
Data Source
AI summary
A method is provided for projecting a guide line onto a road surface. An anticipated trajectory of the motor vehicle is calculated from the speed and steering angle of the motor vehicle. A guide line is projected onto a road surface in front of the motor vehicle. The guide line indicates the anticipated travel path. Whether the motor vehicle is starting a curve is detected based on the steering angle. The guide line contains the shape of a first clothoid in at least a first segment when it is detected that the motor vehicle is starting to travel in a curve.