Design and control of a mobile micromanipulator driven by ultrasonic motors with multidegrees of freedom

A miniature mobile micromanipulator system for performing submillimeter grasping and manipulation tasks has been designed and tested. The system consists of a two-fingered gripper attached to a 5 d.o.f, robot micromanipulator. Features of the system include: (i) the structure of the mobile micromanipulator is composed of high-precision ultrasonic actuators with several degrees of freedom (d.o.f.) (this makes the robot system easy to integrate and allows it to perform directed and precise translation motion or rotation in a plane or in space); (ii) the electronic drivers, based on a bidimensional PWM control architecture, allows us to command the multidirectional manipulator movement accurately, and, through them, to control the position and orientation of the gripper; and (iii) the gripper is actuated by a shape memory alloy actuator and employs strain gage sensors to perform the gripping force control. The prototype version of this mobile micromanipulator can perform micrometer movements with speeds in the range of few mm/s to several 10(-1) m/s and manipulates objects in the size range of 2-0.5 mm. The design of the micromanipulator affords plenty of scope for further miniaturization. With the recent increased interest that has been shown in micro-robotics, the prototype robot system described in this paper could, with further development and miniaturization, form part of a micro-robot assembly system.