Optimal periodic-output-feedback control of active AFM probe for nanomanipulation

AFM based nanomanipulation has been widely studied during recent years. But the efficiency and accuracy are still hot issues. The main problems include nonlinearities and uncertainties such as drift, creep, hysteresis, the deformation of the cantilever caused by manipulation force, etc. These cause difficulties in precisely controlling the tip position, which will cause the tip to miss the object. In this paper an active AFM probe is used to eliminate the uncertainties caused by the deformation of cantilever. The active probe is modeled based on the Euler-Bernoulli theory. An active probe controller of optimal periodic-output-feedback control has been implemented to decrease the position error caused by deformation of cantilever. With the active probe controller the cantilever maintains a straight shape during manipulation by adjusting its flexibility or rigidity. The simulation and nanomanipulation experiments verified the system model and the controller demonstrated that the AFM tip can be controlled precisely.