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Realizing Peg-and-Hole Alignment by Mimicking the Process of an Annular Solar Eclipse


This study focuses on robotic assistance scenario for peg-and-hole alignment with micrometer-order clearance as shown in Fig.1. The objective of the robotic assistance is to cooperate with a human operator based on a coarse-to-fine strategy in which the human operator conducts coarse alignment and the robotic assistance realizes fine alignment.

Robotic-assisted fine alignment was achieved by mimicking the process toward annularity of an annlar solar eclipse as shown in Fig.2 and Fig.3. The first principal axis of a specified image feature (we call it a eclipse feature) was calculated by subtracting the surfaces of a hole part (a small gear with an inner diameter of 1 mm) and a peg part (a shaft with a diameter of 0.95 mm). Control strategy was developed to realize accurate alignment. The effectiveness of the proposed method was verified by experimental evaluation, which showed that peg-and-hole alignments were successfully realized with errors smaller than the clearance of ±25µm.

Fig.1 Scenario of human–robot collaboration for peg and hole alignment.

Fig.2 Alignment strategy mimicking annular solar eclipse

Fig.3 eclipse features of initial and converged states for hole positions at RB and C


  1. Shouren Huang, Kenichi Murakami, Masatoshi Ishikawa, Yuji Yamakawa: Robotic Assistance Realizing Peg-and-Hole Alignment by Mimicking the Process of an Annular Solar Eclipse, Journal of Robotics and Mechatronics, Vol.34 No.5, pp.946-955 (2022) doi:10.20965/jrm.2022.p0946
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