Kinematic Synthesis of Tendon-Driven Manipulators with Isotropic Transmission Characteristics

Abstract

This paper presents a methodology for kinematic synthesis of tendon-driven manipulators with isotropic transmission characteristics. The force transmission characteristics, from the end-effector space to the actuator space, has been investigated. It is shown that tendon forces required to act against externally applied forces are functions of the structure matrix, its null vector, and the manipulator Jocobian matrix. Design equations for synthesizing a manipulator to possess isotropic transmission characteristics are derived. An isotropic transmission is defined as one for which the product of the structure matrix and Jacobian matrix has a unity condition number, and the direction of the null vector points in the [1, 1, ..., 1]T direction. Two examples are used to demonstrate the methodology. It is shown that manipulators which possess isotropic transmission characteristics do have much better force distribution among their tendons.