Mass variations robust controller, for a 3-DOF flexible robot

This article describes a new control scheme designed for a three-degree-of-freedom (3-DOF) flexible robot. The control scheme consists of a two multivariable control loops; the inner loop controls the position of the motors, and the external loop controls the tip´s position and cancels the vibration. The outer control loop, as will be shown, is robust to tip mass variations. Simulations are carried out, supposing different masses with successful results in trajectory tracking. The simulated results demonstrate the behavior of our control algorithm when the system is subjected to a step input and external disturbances in the control signal. Furthermore, trajectory tracking with with a variable mass is also achieved.