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Journal:Mechanism and Machine Theory

Key Words:Inverse kinematics ; 6R robotic arm ; Degree-reduced condition ; Kinematic constraint ; Adjacent parallel axes

Abstract:A systematic and unified kinematic modelling method for a new class of 6R robotic arms is investigated, which separates the coupled joint variables without raising degrees. To begin,  successive products of the tangent-form DCMs and quaternions yield the non-redundant kinematic equations. By providing the derived position vectors, new inverse kinematic formulas are then invented for general 6R robotic arms. Based on this, a degree-reduced condition is found out to ideally reduce the kinematic formulas of five coupling variables to three while the degrees remain constant, which benefits for a light computational resource. A new class of robotic arms satisfying the degree-reduced condition is proposed, including simple kinematic constraints of two adjacent parallel or orthogonal. The inverse kinematic software testing proves the efficiency of the method: the running time is less than 2 milliseconds; the relative position and orientation variations are less than 10− 11. This study can be taken as a theoretical basis for the inverse kinematic research of 6R robotic arms, which provides a brand-new way to establish the kinematic formulas and exhibits a relatively simple kinematic structure for precise industrial use. Moreover, the proposed method is expected to be used to reduce the degrees of kinematic modelling polynomials of higher-DOF robotic arms.

Indexed by:Journal paper

ISSN No.:0094-114X

Translation or Not:no

Date of Publication:2023-01-10