Vibration Suppression on High Speed Parallel Robots with Adaptronic Components

Abstract

The increasing demands on industrial robots regarding speed and precision lead to the investigation of parallel mechanisms, because they are stiffer than serial robotic structures and the obtainable accelerations are higher, due to the fact that the weighty drives are fixed to the reference frame. To further enhance the precision or to shorten the cycle time, unwanted vibrations of the end effector can be reduced by adaptronic devices. These concepts will be most useful in directions orthogonal to the actuation authority of the electric drives. The kinematical and dynamical equations of typical parallel mechanisms are highly non-linear. The position-dependent coefficients of the underlying state space models for the structural vibrations lead to some difficulty in the design of appropriate control strategies. In this paper a five revolute joint parallel test platform with two integrated stack actuators will be presented. After a short summary of the physical realization, an overview of the modeling approach will also be given. The system identification reveals two position dependent eigenfrequencies of approximately 10 and 230 hertz. Finally the promising results of a simulation study, which is based on an interpolating state space control law, will be compared with an implemented control strategy, realized on a dSPACE platform. Both approaches show, that the structural damping of parallel systems with composite fibre materials can be significantly increased