Effect of Additional Compensator Based on Internal Model Principle for Motion Control

Abstract

High-precision motion control requires robust controllers that balance performance with design simplicity. Nominal characteristic trajectory following (NCTF) control has been effective in achieving precise motion without relying on accurate dynamic models or advanced control expertise. However, its performance is influenced by external signals, particularly reference inputs. This paper proposes an additional compensator based on the internal model principle (IMP) to simplify the design of controllers for high-precision motion control. To improve the sinusoidal tracking performance of an NCTF control system while preserving the simplicity of its control design, we implement an additional resonant (R) compensator with a sinusoidal structure, adhering to the IMP for an ideal control structure, without requiring additional parameter tuning. Additionally, a repetitive compensator, designed specifically for tracking periodic signals, and the classical cascade controller commonly used in industry are implemented for comparative performance evaluation. The effectiveness of the additional R compensator was verified through simulations and experiments using a ball-screw mechanism. The results show that incorporating the R compensator significantly reduces tracking errors for low-amplitude, high-frequency sinusoidal signals (2 µm at 5 Hz), achieving an 80% reduction in maximum tracking error. The findings demonstrate that the R compensator effectively enhances tracking precision while preserving the simplicity of NCTF control design.