Trajectory control of a two-link robot manipulator in the presence of gravity and friction

This paper discusses the application of differential flatness to tracking control of a robot manipulator in the presence of gravity and friction. Including these terms in the coupled nonlinear dynamics of the robot increases the complexity of the control. Tracking a robot trajectory under these conditions would require accurate mathematical modeling of the robot. This knowledge will help in generating nominal trajectories and executing accurate tracking. Differential flatness based control enables both possibilities. Flat inputs are designed to drive the robot along its trajectory while eliminating the effects of friction and gravity. The control design is applied to the trajectory tracking control of a two link robot manipulator.