The Tricept robot: Inverse kinematics, manipulability analysis and closed-loop direct kinematics algorithm

This paper is aimed at presenting a study on the kinematics of the Tricept robot, which comprises a three-degree-of-freedom (dof) parallel structure h aving a radial link of variable length. The robot workspace is characterize d and the inverse kinematics equation is obtained by using spherical coordi nates. The inverse differential kinematics and statics are derived in terms of both an analytical and a geometric Jacobian, and a manipulability analy sis along the various workspace directions is developed using the concept o f force and velocity ellipsoids. A Jacobian-based Closed-Loop Direct Kinema tics (CLDK) algorithm is presented to solve the direct kinematics problem a long a given trajectory. Simulation results are illustrated for an industri al robot of the Tricept family.