Structure of microrobots using electromagnetic actuators

We have been developing microrobots which are driven by the clamping of electromagnetic actuators and by the thrusting of piezoelectric transducers. The principle of the microrobots is based on an inchworm motion. The microrobots have three degrees of freedom and realize the linear and the rotational displacements not only on a horizontal plane but also on a slope. Less than 1 /spl mu/m resolution in the linear displacement and less than 1 /spl mu/rad resolution in the rotational displacement were obtained on a flat surface. However our microrobot could not climb on a steep slope. In this paper we discuss the structures of microrobots from the viewpoint of an electromagnetic force. We consider the electromagnetic forces of three microrobots theoretically and experimentally. The electromagnetic force is determined by a magnetic flux which is determined by an electromotive force and reluctance of a magnetic path. Since the microrobots differ in their electromagnetic paths, their reluctances and electromagnetic forces are different from each other. We also discuss the linear and rotational displacements of the microrobots theoretically and experimentally.