Residual vibration suppression using initial value compensation for repetitive positioning

This paper presents a novel residual vibration suppression methodology for the repetitive fast-response and high-precision positioning in machine tool drives. In sequential positioning motions, as the interval period of position references becomes shorter, the residual vibration in response due to undesired initial values deteriorates the positioning accuracy, since the positioning controller is generally designed on the condition that initial state variables are zero. In this research, an initial value compensation (IVC) approach is proposed under the theoretical study on effects of the initial values on the position transient response. The IVC can appropriately assign poles and zeros of the transfer characteristic of position output for the initial values by applying an additional input corresponding to the initial state variables, enabling the response to be residual vibration free. The desired positioning performance, as a result, can be achieved in repetitive motions with arbitrary interval period. The effectiveness of the proposed compensation has been verified by numerical simulations and experiments using a positioning device of industrial machine tools.