MIMO SELF-SENSING CONTROL OF A PIEZOELECTRIC TUBE SCANNER

Piezoelectric tube scanners are commonly used in Scanning Probe Microscopy (SPM) to provide the scanning motion of the tip or sample. Oscillations due to the weakly damped resonances of the scanner are a major source of image distortion in SPM-imaging. In this contribution, multiple input-multiple output (MIMO) self-sensing actuation of a piezoelectric tube scanner is presented, allowing to actively dampen the scanner oscillations. By connecting the tube scanner in a capacitive bridge-circuit, the piezoelectric tube is simultaneously used as a sensor and actuator In order to enable the use of low-order decentralized controllers, the cross-talk between both axes is reduced by compensating for the capacitive coupling. The MIMO self-sensing actuation allows to actively dampen the scanner's fundamental resonance by 18dB, while simultaneously reducing the resonance induced coupling by 30dB. Experimental results verify a significant reduction of the scanner oscillations in both positioning axes during fast scanning.