Vibration Suppression on High Speed Parallel Robots with Adaptronic Components

Abstract

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