Structural Synthesis of Fully-decoupled 3T2R Parallel Robotic Manipulators

摘要

Based on the theory of screws and the principle of one leg driving by a independent motor, a method of structural synthesis of Fully-decoupled three-translational and two-rotational (3T2R) parallel mechanisms was proposed, the parallel mechanism adopted with Independent drive whose output link is provided by the corresponding motion. Firstly, according to the prescribed characteristics of each mechanism limb, a methodology is proposed that makes use of the theory of screws to synthesize desired forms for both the direct and the inverse Jacobian matrices; Secondly, according to the feature both the direct and the inverse Jacobian matrices, the actuation screws, actuated screws and mobile un-actuated screws of every limb were confirmed at first based on the reciprocal screw theory, and the leg structure is obtained. Then the structural synthesis of each kinematic chain for Fully-decoupled 3T2R parallel robotic manipulators was performed in the light of different connectivity of the limbs; Finally, the anticipant manipulators were synthesized by using the rules and regulations of Fully-decoupled parallel mechanisms and a lot of parallel mechanisms were obtained. Many 3T2R of Fullydecoupled parallel mechanisms are synthesized by using the above method. In particular, the direct Jacobian matrix is made diagonal and constant throughout the workspace. Motors are mounted one per leg and each one of them actuates one of the degrees of freedom of the output body through a constant one-to-one velocity relation. Such mechanism control is simple, and the problem of link interference is potentially simplified, also has good prospects.