An approach to control input shaping with application to coordinate measuring machines

Dimensional measurements obtained with Coordinate Measuring Machines (CMMs) are negatively affected by self-induced structural vibrations. In this pap er a control strategy that reduces the structural vibrations in a CMM is ou tlined and experimentally demonstrated. The control strategy, designated th e Feedforward Filter, is developed by establishing the relationship between contemporary controller input shaping techniques and traditional notch fil tering methods. Issues on both robustness and multiple mode vibrations are addressed. Controller input development takes place in the discrete time do main. This method provides results identical to those for optimal command i nput preshaping obtained through non-linear programming methods and require s considerably less computational effort. Experimental results show a 50 pe r cent reduction in the peak-to-peak magnitude of structural vibrations as compared to unshaped bang-bang trajectories.