Robust control of a 3-DOF hybrid robot manipulator

This paper introduces a 3-DOF hybrid robotic manipulator which is constructed by combining a parallel mechanism and a pantograph to increase the high stiffness, as well the as workspace. We analyze its kinematics and dynamics by applying Lagrange's method. Subsequently, we propose a robust tracking controller based on the Lyapunov approach for the manipulator in the presence of uncertainty. The scheme consists of two parts. The first part is the model-based computed torque controller, which is used to stabilize the nominal robot system. The second part is a robust compensating controller, which is designed to handle the uncertainty in the system. We propose a controller designed in Cartesian coordinates. The proposed controller guarantees practical stability.