Abstract
Industrial robots have lumped flexibility at joints as well as distributed flexibility due to elasticity of arms. Because of the flexibility, undesirable vibration occurs during motion. In this paper, an equivalent spring which represents the flexibility is introduced, and equations of motion of robot links and equations of vibration of end-effector are derived by using Lagrangian dynamics. Motor torques should be controlled in such a way that required response of motor positions is achieved and at the same time the vibrations disappear as quickly as possible. For measuring the vibrations, 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 shown.
