Polishing plays an indispensable role in optical processing, especially for large-aperture optical reflective mirrors with freeform surfaces. Robotic polishing requires effective control of the contact force between the robot and the mirror during processing. In order to maintain a constant contact force during polishing, traditional polishing robots rely on closed-loop control of air cylinders, whose performances heavily rely on high-fidelity force sensing and real-time control. This paper proposes to employ a compliant constant-force mechanism in the end-effector of a polishing robot to passively maintain a constant force between the robot and the mirror, thus eliminating the requirement for force sensing and closed-loop control. The compliant constant force mechanism utilizing the second bending mode of fixed-guided compliant beams is adopted and elaborated for the passive end-effector. An end-effector provid- ing a constant contact force of 40 N is designed and prototyped. The polishing experiment shows that the passive constant-force end-effector provides stable contact force between the robot and the mirror with fluctuation within 3.43 N, and achieves RMS (Root Mean Square) lower than λ/10 (λ = 632.8 nm) of the polished surface of the large-aperture optical reflective mirror. It is concluded that the constant-force compliant mechanism provides a low-cost and reliable solution for force control in robotic polishing.

Jian Zhang;Liangxiao Zhao;Lingling Li;Fulei Ma;Guimin Chen

School of Mechano?Electrical Engineering,Xidian University,Xi'an 710071, China;Xi'an Institute of Optics and Precision Mechanics of CAS,Xi'an 710119,China;University of Chinese Academy of Sciences,Beijing 100049,China;Institute of Robotics and Intelligent Systems,Xi'an Jiaotong University, Xi'an 710049,China

中国机械工程学报

[1]Jian Zhang;Liangxiao Zhao;Lingling Li;Fulei Ma;Guimin Chen-.Design of Passive Constant?Force End?Effector for Robotic Polishing of Optical Reflective Mirrors)[J].中国机械工程学报,2022(06):65-73

Effector,Mirrors,prototyped

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