Lateral Control During Backward Motion Using Virtual Forward Path
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Solution Overview
Problem
Automated vehicles face complexity in controlling lateral movement during backward motion, particularly at low speeds, due to increased phase contributions, making it difficult to follow desired paths and execute maneuvers like backing out of driveways or parking.
Innovation Solution
A method and apparatus that reflect waypoints of a backward path along a perpendicular axis to create a virtual forward path, allowing for control of lateral movement by adjusting road wheel angles to minimize deviation from this path, using one-dimensional nonlinear optimization and outputting road wheel angle commands to a front wheel actuator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If automated lateral control is applied during backward motion, then path following accuracy is improved, but control complexity increases due to phase contributions
Solution Approach 1:
The patent applies coordinate transformation to invert the control problem by reflecting the backward path waypoints across the longitudinal axis to create virtual forward path waypoints. This inversion transforms the complex backward motion control into a simpler forward motion control problem, where standard lateral control algorithms can be applied directly without dealing with phase contribution complexities
Solution Approach 2:
The patent creates a virtual copy of the backward path by generating reflected waypoints that represent the mirror image of the actual backward trajectory. This virtual forward path serves as a simplified model that captures the essential geometric characteristics needed for control, allowing the system to control lateral movement without directly computing complex backward motion dynamics
2Manufacturing precision
If road wheel angle adjustment is used to control lateral movement, then path following precision is improved, but response time increases due to optimization computations
Solution Approach 1:
The patent performs coordinate transformation and waypoint reflection in advance to pre-compute the virtual forward path waypoints before the actual backward motion begins. This preliminary processing of path geometry allows the real-time control system to simply follow the pre-transformed waypoints without performing complex optimization computations during motion, significantly reducing response time while maintaining precision
Solution Approach 2:
The patent divides the control task into separate stages: first transforming the backward path into virtual forward waypoints, then using these pre-computed waypoints to control road wheel angles. This segmentation separates the computationally intensive coordinate transformation from the real-time control execution, allowing high-precision path following without real-time optimization delays
Data Source
AI summary
A method and apparatus that control lateral movement of the vehicle during backward motion are provided. The method includes loading a desired backward path of vehicle, the backward path comprising waypoints to be traveled along during a rearward motion of the vehicle, reflecting the waypoints along a reflection axis perpendicular to a longitudinal axis that runs from front to back of the vehicle such that the reflected waypoints define virtual forward path; and controlling lateral movement of the vehicle to follow the waypoints along the forward path while the vehicle is traveling in a backward direction.