||One of the limiting factors on the speed of a Scanning Probe Microscope (SPM), are the dynamics of the scanner stage which suffer from hysteresis, creep and undamped resonances. To be able to control these dynamics, one should be able to measure the displacement of the scanner stage with nanometer resolution. However, commercially available position sensors (e.g. strain gauges) are limited in bandwidth and have a relatively high level of sensor noise.
Rather than using position sensors, one could also use the selfsensing capabilities of piezomaterial to sense the external forces on the piezo-actuator. This method has shown to be very sensitive within the higher frequency band where the stage dynamics start to play a roll. Selfsensing techniques are however not capable of measuring DC-components and the relatively low frequent effects of hysteresis and creep.
The assignment of this thesis is combining both measurement techniques described above, and fusing both measurement signals together, e.g. by use of Kalman filtering techniques. This should result in a position sensor system with a relatively high bandwidth. The position estimate of this sensor fusion method can than be used to control the position of the scanner stage (e.g. feedback control techniques or ILC).
The content of this assignment will be about 50 percent theoretical and 50 percent practical work. The resulting estimator should be implemented for an available AFM-scanner using real-time prototyping hardware.
If you are interested in this or another project in control of micro- and nanosystems, please feel free to drop by.