Pose measurement for cooperative spacecraft based on Lighthouse tracking system and the precision analysis

Current cooperative spacecraft relative pose measurement methods face the struggles of balancing field of view and precision as well as lacking straightforward precision metrics. We propose a method based on lighthouse tracking system, which can balance both field of view and precision and introduce a precision assessment metrics. The lighthouse tracking system comprising of laser emitters and multiple light sensors realizes angular measurements to achieve relative pose measurement. Leveraging the angular measurement principles of lighthouse tracking system, we present a PnP pose estimation algorithm. To address the precision analysis of pose measurement, we establish an angular error propagation model for PnP problem, and introduces dilution of precision for attitude and position as a precision assessment metric. Experimental results indicate that the lighthouse tracking system achieves attitude and position measurement precision at the order of 0.1° and millimeters, respectively. The dilution of precision for attitude and position demonstrates a consistent pattern in estimating precision relative to experimental results, which can be utilized for a rapid assessment of measurement precision and guides the optimization of sensor installation layout. Moreover, the angular error propagation model is applicable to measurement systems involving PnP problems involved in the monocular vision. © 2023 Science Press. All rights reserved.