A Parallel, Four Degree-of-Freedom Robotic Wrist

摘要

Abstract Kinematic considerations are presented for a parallel, four degree-of-freedom robot wrist resembling the Clemens coupling, a constant-velocity joint first described in his 1872 patent. In its new form as a wrist, this device provides general orientational mobility as well as axial displacement through a plunge motion. A possibly more important hybrid of this wrist is identified as an artificially constrained, spherical, three degree-of-freedom pitchyaw-roll wrist that can easily be derived from this new concept. Because of its parallel architecture, the new wrist design displays favorable attributes including high strength-to-weight and stiffness-to-weight ratios, a large workspace, and an open center construction. Closed-form forward and inverse kinematics of the wrist are derived for both the three and four degree-of-freedom configurations, thereby making it a likely candidate for real-time control. Workspace plots are also presented that demonstrate the dexterity of the proposed wrist.