Linear Equivalent Step-Control Strategy for the Traveling-Wave Micromotor Rotating Platform Based on a MEMS Three-Ring Capacitive Angular Position Sensor

In this article, we propose a linear equivalent step-control strategy for the traveling-wave micromotor rotating platform, utilizing a microelectromechanical system (MEMS) three-ring capacitive angular position sensor. Designed for practical applications, the strategy incorporates a simplified online angle demodulation process that satisfies step-control requirements. In addition, we developed a more robust method for identifying the absolute zero position feature based on abrupt changes in the inner ring peak-to-valley values. A control strategy based on linear equivalent angle demodulation, which requires fewer computational resources, is presented, along with a step-angle refinement technique to enhance resolution. Experimental results indicate that the current control strategy can effectively locate the zero position of the traveling-wave micromotor rotating platform under fluctuation, achieving a step-angle precision of 0.216° and an angular position repeatability (APR) of 0.237°, with no cumulative error. Our study marks the first successful implementation of a multiposition step control combining the traveling-wave micromotor and the MEMS three-ring capacitive angular position sensor in practical applications, providing a promising solution for its use in various fields.