A high precision micropositioner with five degrees of freedom based on an electromagnetic driving principle

A five degrees of freedom high precision micropositioner based on spring suspension and electromagnetic driving has been designed, constructed, and tested. The device consists of two parts: a moving part and a stationary part. The moving part, named as ‘‘motor’’, is formed with a rigid frame and three groups of coils fixed on it. The stationary part of the device, called ‘‘stator’’, includes a chassis and twelve U-shaped magnetic ‘‘shoes’’. The motor is attached to the stator with flat springs whose linear suspension allows it to move in all dimensions except the rotation around z axis. The coils have been laid out in such a way that fractions of them pass through the air gaps between the facing magnets in the magnetic shoes. When electrical currents are supplied to the coils, the resulting Lorenz forces drive the motor to move in the five degrees of freedom allowed by the spring suspension. Since the system is inherently stable and there is no mechanical friction, the open-loop resolutions of the device are found to be limited only by that of the 12-bit D/A board used. A closed-loop translation resolution of 0.3 μm has been achieved over a working space of 180 μm by 180 μm by 680 μm. A closed-loop rotation resolution of 2.73×10−6 rad has been achieved over a working space of 1.38×10−3 rad. Potentially the device can be used for high precision microprobing and testing, cellular biology, microsurgery, and testing of micromechanical devices in the fast developing MEMS area.