Abstract:

To enhance the real-time performance and accuracy of star point centroid extraction， an improved run-length encoding algorithm based on field programmable gate array（FPGA） was proposed for fast star point extraction. The algorithm combines the characteristics of star point targets with the parallel processing structure of field programmable gate array， addressing the shortcomings of the traditional run-length encoding algorithm that requires setting equivalence tables for label merging and multiple rounds of polling for run-length encoding during extraction. It only requires scanning the image once， and after a delay of several clock cycles， the centroid coordinate of the star point can be extracted. Finally， the algorithm is tested and validated on an field programmable gate array of a star sensor. With a clock frequency of 50 MHz and an input image resolution of 1 280×1 024 pixels， the algorithm takes about 2 us to extract the centroid of the star point， and the position is completely accurate. Compared to the nearly 19 ms consumed by centroid extraction using an Advanced RISC Machine（ARM）， the improved algorithm demonstrates significant advantages and holds notable engineering application value.

Key words: signal and information processing, centroid extraction, field programmable gate array （FPGA）, connected domain scan, star sensor, run-length encoding