Miniaturized Twin-legged Robot with an Electromagnetic Oscillatory Actuator

There have been many studies on the moving mechanism of micro robots, such as stick-slip, inchworm like motion, and impact drive. Novel actuators like lead zirconate titanate (PZT), Shape Memory Alloy (SMA), magnetostrictive materials, electromagnetic actuators, electoractive polymers, ultrasonic linear motors, and dielectric elastomers are utilized to realize the moving mechanism. The use of a conventional electromagnetic actuator is unfavorable, because of a few drawbacks, such as generation of stray magnetic fields, hard to miniaturize to the millimeter scale because of 3D integration and a scaling law, and power consumption to maintain a certain position. This research presents a micro robot that uses an electromagnetic actuator customized and developed for micro robot. The electromagnetic actuator is designed from a Brushless Direct Current (BLDC) motor to overcome the drawbacks mentioned above. The developed robot is composed of two electromagnetic actuators. The overall size of the robot is 20 mm × 11 mm × 9 mm (length × height × width) and the weight is 3 g. The developed robot is able to move bidirectionally with a maximum moving speed of 15.76 mm·s−1 (0.79 body-length per second). The optimal conditions of an input signal are calculated theoretically and verified with experiments.