Design and control of a novel electromagnetic driver for wireless micro-robots

Electromagnetic actuator (EMA) is considered as a promising mechanism for the wireless micro-robotic locomotion control. Generally, EMA systems employ function generators and power amplifiers to drive coil pairs, and operated in open loop mode, by which system dynamic response and steady state accuracy are no good enough. This paper presents a novel prototype of a real time, two-stage, and close-loop EMA system. The proposed circuit consists of a phase-shift full-bridge (PSFB) converter, a two-phase inverter, and a digital controller based on DSP. The function of the PSFB converter is to supply stable dc voltage, while the current-source two-phase inverter is used to generate independent sine and cosine power signals. The relationship between DC link voltage and output regulation of the inverter is studied and a novel control strategy based on feedforward complex PI controller for the two-stage driver is proposed to achieve high accuracy and fast dynamic response. The experimental results based on a 360W prototype are discussed to evaluate the proposed driver circuit and control method.