Development of micro-machined planar manipulators

Study of micro scale manipulators is challenging because of the microscopic scale. This thesis investigates the kinematic and dynamic behavior of planar polysilicon MEMS 3-DOF manipulators. The manipulators consist of three evenly distributed legs and one centrally located platform. Each leg is supported by an elastic spring, which is called S-joint, and is powered by a thermal actuator.

A rigid body kinematic model has been developed to study the work envelope of the manipulators and to facilitate automatic control. Experimental results were compared with predictions based on this model. Using the developed kinematic model, the geometry of manipulators has been optimized to obtain large work envelopes. The optimization included: radius of the platform and stroke of S-joints. Corresponding design guidelines have been provided as well. The largest measured work envelope, of the designed manipulators, is an area of approximately 20 μm in diameter.

A finite element model and a discrete spring-mass model of the manipulator have been developed. The numerical results of the spring-mass and the finite element models application revealed special properties of the manipulator such as, modes with repeated resonant frequencies, in-phase modes and out-of-phase modes, etc. The simulated results were compared with the experimental results and they agreed with each other.

Developed motion control algorithms included point to point and path control. They utilized vision system for feedback. The algorithms were applied successfully in experiments with 1-DOF and 3-DOF devices and resulted in errors of less than 0.3 μm.