Modelling and vibration control of a flexible manipulator with three axes by using accelerometers

Abstract

Industrial robots have lumped flexibility at joints as well as distributed flexibility due to the elasticity of their arms. Because of the flexibility, undesirable vibration occurs during motion. In this paper, an equivalent spring which represents the flexibility is introduced, and the equations of motion of robot links and equations of vibration of the end-effector are derived by using Lagrangian dynamics. Motor torques should be controlled in such a way that the required response of the motor positions is achieved and at the same time the vibration disappears as quickly as possible. For measuring the vibration, three accelerometers are installed at the tip of the forearm. A robust feedback control law is derived by using the root locus technique. Several successful experimental results are given.