Development of a compliant rotary-to-translational transmission mechanism for a micro-parallel kinematic mechanism

his paper presents the integrated design of an electrostatic comb-drive rotary actuator and a compliant slider-crank mechanism to transmit the motion from a rotary actuator into translational motion. This integrated design yields a transmission exhibiting minimal sliding contact with supporting substrate. This design is applicable to micro-Parallel Kinematic Mechanisms (PKM) for micro/nano positioning and manipulation of optical components including lenses and mirrors. For a 3 degree of freedom micro-PKM, the rotational motion of three electrostatic torsion actuators is converted into translational motion through a compliant transmission device. The compliant transmission is based on a slider-crank mechanism that uses flexible beams for the linkages. The input of the rotary motion through the transmission's crank yields translational motion of the slider component. The slider is supported via a Roberts straight-line mechanism which yields a suspended slider design and therefore reduced friction and wear within the transmission. Furthermore, the slider component of the transmission provides a linear force-displacement relationship beneficial for embedded sensing. This paper describes the design of the actuation and transmission system and its integration into the kinematics of the micro PKM motion.