Patch Point
Author: Tianjiang Says
Website: https://cislunarspace.cn
Definition
A patch point (splicing point) is a node where adjacent trajectory segments are connected in multi-segment orbit computation. Patch points serve as boundary conditions that ensure continuity of position and velocity across segments. Their selection significantly affects the convergence and accuracy of the orbit solution.
Role in Orbit Computation
In multi-segment orbit design (e.g., transfer trajectories, multi-revolution orbits), the trajectory is divided into segments connected at patch points:
- Each segment is propagated independently
- Continuity conditions are enforced at patch points
- Differential correction adjusts the patch point states to satisfy all constraints
Selection Criteria
| Criterion | Description |
|---|---|
| Geometric location | Place patch points at physically meaningful positions (e.g., perilune, apolune, crossing points) |
| Dynamics | Choose points where the dynamics change character (e.g., near libration points) |
| Numerical conditioning | Avoid placing patch points where the state transition matrix is ill-conditioned |
| Adaptive selection | Dynamically adjust patch point positions during iteration to improve convergence |
Adaptive Patch Point Selection
For complex orbits, adaptive patch point selection adjusts the number and positions of patch points based on the orbit geometry and convergence behavior. This approach:
- Automatically identifies regions requiring finer segmentation
- Improves convergence for sensitive orbits
- Reduces user intervention in orbit computation
Related Concepts
References
- Chen Yuju. DRO Orbit Design and Control Research for Cislunar Space Situation Awareness[D]. 2024.