Purpose – The purpose of this paper is to present the design and implementation of a new manipulator with six joints driven by a single DC motor. Design/methodology/approach – The manipulator consists of several modules, each of which has the twisting and pivoting degrees of freedom. Two clutches and one brake are mounted to control each joint. A clutch model based on PWM control is built to compute the average velocity of each clutch. Two parameters are involved in the model: PWM frequency and duty ratio. PWM frequency is limited by the natural frequencies of structure with all postures. The theoretical duty ratio should be adjusted according to the clutch model. Two experiments – line tracking and arc tracking – are carried out to verify the effectiveness of the control system. Findings – The study has designed a manipulator with six joints driven by a single DC motor which powers all the modules through a main shaft and several clutches. In the manipulator, all the modules are supplied with a constant speed input and provide a bi‐directional variable output. Experimental results show the clutch model built for the manipulator can be applied to the joint control of all multi‐joint manipulators. Originality/value – The paper describes a dexterous and light‐weight manipulator driven by a single motor and designed with bi‐directional joints.
Industrial Robot: An International Journal – Emerald Publishing
Published: Jan 11, 2011
Keywords: Robotics; Electric motors; Control systems; Actuators