Nanometer-Order Contouring Control in a Feed Drive System Using Linear Ball Guides by Applying a Combination of Modified Disturbance Observer and Repetitive Control

This paper proposes a quadrant glitch compensation method to achieve nanometer-level accuracy of contouring control for a feed drive system using linear ball guides. The proposed method is a combination of a modified disturbance observer (“disturbance suppressor”) and an improved repetitive control scheme. Sinusoidal motion tests with 1 mm amplitude and 0.1 Hz driving frequency were conducted using a single-axis feed drive system to verify the quadrant glitch compensation ability of this method. First, the repeatability of the quadrant glitches in the experimental system was verified, which is the most important characteristic required for compensation via repetitive control. Then, by applying the combination of disturbance suppressor and conventional repetitive control, the amplitudes of the quadrant glitches were decreased to less than 1 nm; in other words, the ratio of the magnitude of the quadrant glitch to the amplitude of the position reference was less than 1/1,000,000. However, for both compensation schemes mentioned before, vibrations were generated when the feed speed increased. Moreover, the amplitudes increased with the number of repetitions. The reason for the vibrations was identified as the repetitive control mechanism. To suppress these vibrations, the repetitive control was applied only to narrowed regimes near the quadrant glitches. Thus, the maximum contouring error was decreased to 2 nm. In addition, the nonlinear spring behavior of the linear ball guides was confirmed to affect the stability of the control systems. © 2021, International Society for Nanomanufacturing and Tianjin University and Springer Nature Singapore Pte Ltd.