Path Planning Autopilot for Vehicle Path Joining
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Solution Overview
Problem
Conventional autopilot systems for vehicles struggle with maintaining high performance when a vehicle is far from the desired path, often resulting in inefficient guidance and oscillations when joining a path, due to tradeoffs between small and large signal regimes.
Innovation Solution
A path planning autopilot system that uses a combination of feedback and feed-forward control, allowing direct control over constraints like maximum steering angle and rate, and calculates efficient joining paths with continuous curvature, using clothoids and other segments to guide the vehicle from an arbitrary initial configuration to a desired path, regardless of distance from the path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high feedback gain is used to keep cross track error small in the small signal regime, then manufacturing precision is improved, but reliability deteriorates due to steep approaches and oscillation when joining the path
Solution Approach 1:
The autopilot system dynamically adjusts control parameters based on the vehicle's distance from the desired path. When far from the path (large signal regime), the system uses different control gains and strategies compared to when close to the path (small signal regime). This dynamic adaptation allows the system to maintain stability during path joining while achieving high precision during path following, resolving the contradiction between precision and reliability
Solution Approach 2:
The system changes control parameters (such as feedback gain, prediction horizon, and control authority) based on the operating regime. In the large signal regime, parameters are adjusted to prevent oscillation and ensure stable approach, while in the small signal regime, parameters are optimized for high precision tracking. This parameter adaptation resolves the contradiction by optimizing performance for each specific operating condition
2Reliability
If conventional feedback autopilot is used to avoid undesirable large-signal behavior through heuristic limits, then reliability is improved, but productivity deteriorates due to inefficient large-signal guidance
Solution Approach 1:
The control space is segmented into different regimes based on the vehicle's distance from the desired path. The system identifies whether the vehicle is in the small signal regime (close to path) or large signal regime (far from path) and applies appropriate control strategies for each segment. This segmentation allows efficient guidance in the large signal regime without compromising reliability, as each regime has optimized control parameters
Solution Approach 2:
The autopilot dynamically switches between different control strategies based on the current operating regime. In the large signal regime, the system uses control laws optimized for efficient approach and path joining, while in the small signal regime, it switches to high-precision tracking modes. This dynamic strategy selection improves overall productivity while maintaining reliability across all operating conditions
3Manufacturing precision
If feedback control is used to guide vehicle close to desired path, then manufacturing precision is improved, but loss of time increases when vehicle is far from path due to inefficient approach
Solution Approach 1:
The autopilot performs preliminary actions to efficiently bring the vehicle from far positions toward the desired path before engaging high-precision feedback control. In the large signal regime, the system uses predictive control and optimized trajectory planning to rapidly reduce cross-track error, preparing the vehicle for the subsequent precision tracking phase. This preliminary efficient approach reduces the time spent in low-precision regimes without compromising final path following accuracy
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
A path planning autopilot guides vehicles even when they are far from a desired path.