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

In this paper, 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. Additionally, 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 of 0.237°, with no cumulative error. Our study marks the first successful implementation of a multi-position 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.