Control input shaping for coordinate measuring machines

Structural vibrations in coordinate measuring machines deteriorate measurement quality at high operating speeds. In this paper, a control strategy is presented that appropriately shapes inputs to a CMM motion controller in order to avoid exciting unwanted vibrations. This control strategy utilizes a traditional bang-bang trajectory and new filtering technique called the feedforward filter. The control input construction takes place in the discrete time domain and can be accomplished with considerably less computational effort than currently accepted methods. Experimental results show that utilizing a FF filtered trajectory results in approximately a 50% reduction in peak-to-peak magnitude of structural vibrations as compared to unshaped bang-bang trajectories.