Sensorless XY Scanning Mechanism for Precision Applications

Micro and Nano positioning systems demands high order of precision and repeatability. Positioning accuracy depends on resolution of positioning sensor. Present aim of work is to demonstrate theoretically and experimentally the novel concept of sensor-less operation of scanning mechanism which eliminates the high cost sensor from feedback control loop. Experimental setup (consists XY flexural mechanism, voice coil motors, current and voltage sensing circuitry, position estimator algorithm, Microcontroller) is developed, and its system identification is conducted using highly accurate optical encoder (resolution 50 nm via due experimentation. Position estimator algorithm is developed and experimentally tested, and its accuracy is validated with due experimentation. It is observed that positioning accuracy of less than 5 microns is achieved. PID control is designed and experimentally implemented and real-time scanning accuracy of less than 5 microns is achieved at scanning speed of 10 mm/s.