Numerical approaches for residual vibration free positioning of elastic robots

Today increasing the speed of moving machines with the same or even better precision can often only be realized if flexibilities are taken into account. In order to avoid a stiffer and therefore heavier structure, the flexibility must be considered in the control design. Numerical optimization approaches as well as an analytical feed forward control for linearly actuated robots like placement machines or stacker cranes are presented. These methods help to reduce the time required for positioning in dynamic automation scenarios where the structure's elasticity is essential for achieving high positioning precision in a minimum of time. Backlash in the gear limits standard closed loop active damping controller's capabilities in respect to the achievable damping constant. Therefore, feedforward trajectories avoiding residual vibrations are desirable to reduce the positioning time to a structural given limit.