A four degree of freedom microrobot with large work volume

This paper presents a unique four-axis articulated MEMS robot, constructed by microassembly, targeting micro and nano scale manipulation and probing applications. The first version of this microrobot has a 2P2R (Prismatic Prismatic Revolute Revolute) kinematic configuration, occupies a total volume of 3mm × 2mm × 1mm, and operates within a workspace envelope of 50µm × 50µm × 75µm. This is by far the largest operating envelope of any independent micropositioner with non-planar dexterity. As a result, it can be classified as a new type of 3 dimensional miniaturized top-down assembly robot with dimensions smaller than 1 cm. The robot incorporates a combination of miniature flexures and cables to drive its joints from high force MEMS actuators. Actuation is accomplished via two banks of in-plane electrothermal actuators, one coupled through an out of plane compliant socket, and the other one coupled remotely via a 30 µm diameter Cu wire. In this paper, we decouple the motion of the robot joints by identifying the robot Jacobian, and we offer preliminary experimental characterization of the microrobot repeatability. Results show that the robot is repeatable to under 0.5 µm along XY and 0.015 degrees along pitch and yaw degrees of freedom.