Behnam khodabandeh - Department of Mechanical Engineering, University of Isfahan, Isfahan, Iran.
Amir Hassan monadjemi - Department of Computer Engineering, University of Isfahan, Isfahan, Iran.

This article describes the design, dynamic modelling and experimental validation of a new three-degree-of-freedom robotic arm. The arm was designed on the assumption that all its mass was concentrated at the tip. Therefore, the arm was built with lightweight links using plexiglas material, and all the actuators were located at the joints. From the dynamics point of view, this mechanism also decouples the forces transmitted by the actuators to the tip of the arm. On the assumption that all the mass is concentrated at the tip, a compliance matrix can be used to model the oscillations of the structure. Then, dynamics of the arm becomes very simple (a lumped single mass model instead of the usual distributed mass model), and its control system can be significantly simplified: minimum sensing effort is required. These design specifications have been experimentally validated on the prototype we have built. Experimental results showed that the proposed mechanism had effectively provide the torque required to support the robot and the end effector mass, thus allowing the prospective use of low-cost motors and speed reducers for high performance root arms.

Robotic Arm, Robot control, Mechanical manipulator