Trailer Backup Trajectory Planner with Waypoint Curvature Control
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Solution Overview
Problem
Reversing a vehicle while towing a trailer is challenging, especially for unskilled drivers, due to the need for opposite steering inputs and amplified errors leading to jackknife conditions, and existing systems assume a zero curvature path, limiting their usefulness in real-world scenarios.
Innovation Solution
A trailer backup assist system with a state estimator and trajectory planner that generates circular trajectories and switches modes to guide the trailer through waypoints, using a curvature controller to manage path curvature and prevent jackknife conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing trailer backup assist systems assume a zero curvature path, then the system simplicity is maintained, but the usefulness is significantly limited in real-world scenarios
Solution Approach 1:
The system dynamically adapts between different operating modes (first mode for curved paths with non-zero curvature, second mode for straight paths with zero curvature) based on real-time path requirements. This allows the system to handle diverse real-world scenarios while maintaining operational simplicity when applicable, directly resolving the contradiction between adaptability and complexity
2Reliability
If small steering errors occur while backing a vehicle with a trailer, then the ease of operation is maintained, but the errors are amplified causing the trailer to depart from the desired path
Solution Approach 1:
The system continuously monitors the actual trailer path and compares it with the desired path, then provides corrective steering commands to eliminate deviations. This feedback mechanism compensates for small steering errors before they are amplified, maintaining path accuracy while allowing the driver to operate the system easily without requiring precise manual steering control
3Speed
If the vehicle travels at high speed in reverse when a jackknife condition occurs, then the productivity of the backup maneuver is improved, but the relative movement leads to contact between vehicle and trailer causing damage
Solution Approach 1:
The system detects jackknife conditions in advance and takes preliminary countermeasures by reducing vehicle speed and adjusting steering commands to prevent the condition from worsening. This prevents the harmful relative movement between vehicle and trailer that would cause contact and damage, while still allowing efficient backup operations under normal conditions
Data Source
AI summary
A trailer backup assist system, according to one embodiment, includes a state estimator that determines a current position of a trailer relative to a plurality of waypoints. A trajectory planner may then incrementally generate a path from the current position to the plurality of waypoints. The trajectory planner has a first mode that generates first and second circular trajectories tangent to one another connecting between the current position and a waypoint of the plurality of waypoints. A second mode of the trajectory planner generates the second circular trajectory between the current position and the waypoint after the trailer traverses the first circular trajectory. Also, a third mode of the trajectory planner switches to the first operating mode when the trailer reaches the waypoint for guidance to a subsequent waypoint. A curvature controller guides the trailer based on a curvature of the respective first or second circular trajectories.