Kinematic performance analysis of redundantly actuated 4-UP_S&UP parallel manipulator

The kinematic performance analysis of a redundantly actuated 4-UP_S&UP parallel manipulator is dealt, which is a modified version of the 3-UP_S&UP parallel mechanism within the Tricept robot by adding a 6-DOF active limb. Compared to the 3-UP_S&UP mechanism, the proposed mechanism has higher payload capability and higher static/dynamic performance thanks to the additional active limb. On the basis of the inverse kinematics and the derivation of the 7×6 generalized Jacobian of the 4-UP_S&UP mechanism, the 4×3 dimensionless Jacobian can be obtained, which is the mapping between the rates of the actuated joints and the linear velocity of the reference point on the platform, and its condition number is then proposed as the local kinematic performance index. By carrying out the comparison study between the 4-UP_S&UP and the 3-UP_S&UP mechanisms given the same set of dimensional parameters, it is concluded that the kinematic performance of the 4-UP_S&UP mechanism is higher than that of the 3-UP_S&UP mechanism. © 2016 Journal of Mechanical Engineering.