# Persistence-Weighted Performance Metric for PID Gain Optimization in Optical Tracking of Unknown Space Objects

## TL;DR

This paper introduces a new metric for optimizing PID controllers in optical tracking of unknown space objects, improving accuracy and stability.

## Contribution

The novel Persistence-Weighted Tracking Index (PWTI) combines spatial precision and temporal continuity for controller tuning.

## Key findings

- PWTI outperforms RMS and PT metrics in alignment accuracy and consistency.
- A genetic algorithm using PWTI effectively tunes PID gains for optical tracking.
- Results validate PWTI as a better performance indicator for unknown space object identification.

## Abstract

Optical tracking of unknown space objects requires both spatial accuracy and temporal stability to enable high-resolution identification through narrow field-of-view sensors. Traditional performance indices such as RMS error and persistence time (PT) have been used for controller tuning, but they each capture only a subset of the requirements for successful optical identification. This paper proposes a new composite metric, the Persistence-Weighted Tracking Index (PWTI), which combines spatial precision and segment-level continuity into a single measure. The metric assigns a frame-level score based on positional error and accumulates weighted scores over the longest continuous in-threshold segment. Using PWTI as the optimization objective, a genetic algorithm (GA) is employed to tune the PID gains of a frame-by-frame offset correction controller. Comparative simulations under various observation scenarios demonstrate that the PWTI-based approach outperforms RMS- and PT-based tuning methods in both alignment accuracy and consistency. The results validate the proposed metric as a more suitable performance indicator for optical identification tasks involving unknown or uncataloged targets.