Design and analysis of a two-DOF novel drive unit for parallel robots.

摘要

This thesis reports on the design and analysis of a novel robotic drive unit, intended as the driving kernel for multi-degree of freedom (dof) parallel manipulators. The transmission system of this unit features a planetary gear train and a ball-screw mechanism. Due to this special transmission design, two driving motors can be placed on the fixed base, thereby enhancing the load-carrying capacity of the robotic drive unit. Parallel robots constructed and actuated with the proposed units should exhibit higher load-carrying capacity and faster motion capability, as compared to existing drives. The conceptual design of the unit is first proposed, and a design alternative is then discussed. The application of this novel drive unit is illustrated by the example of integrating three such drive units into a six-dof parallel manipulator with three Universal-Prismatic-Spherical (UPS) legs. With six actuators installed on the fixed base, such a manipulator can be endowed with high stiffness, high speed, high accuracy and high load-carrying capacity. Furthermore, a testbed is designed in order to verify the kinematic and dynamic performance of the drive unit. The kinematic analysis of the drive unit, the testbed and the six-dof parallel manipulator is conducted. The CAD modelling and animation results are included to validate the design and the kinematics of the drive unit.