A fast circle detector of non-cooperative target for Tethered Space Robot

Concentrating on recognition of circular modules fixed on non-cooperative target for Tethered Space Robot (TSR), this paper presents a fast circle detector. The pixels´ gradient magnitude and direction are computed in the first step and region-growing method is implemented to generate arc support regions (ASRs). And the corresponding square fitting areas (SFAs) are obtained. Afterward, the Euclidean distances between every coordinates on each ASR and each coordinate of SFA are computed and recorded in an accumulator. Then, a histogram is used to count the frequency of the distances that participates in the accumulator and the parameters of each circle are acquired. Finally, a verification strategy of circular integrity is used to test the detection results. Based on contrast experiments, results indicate that the proposed algorithm is able to detect partial circles, multiple centers or circles in partial occlusion. This method has features of low consumption, wide range of application and strong anti-interference performance.