Sliding Mode Control of AFM in Contact Mode during Manipulation of Nano-Particle

Application of atomic force microscope as a manipulator for pushing-based positioning of nano-particles has been of considerable interest during recent years. However a detailed modelling of the interaction forces and control on the AFM tip is important for prosperous manipulation control, a reliable control of the AFM tip position during the AFM-based manipulation process is a main issue. The deflection of the AFM tip caused by manipulation force is the one of nonlinearities and uncertainties which causes difficulties in accurately controlling the tip position, the tip can jump over the target nano-particle then the process will fail. This study aims todesign a sliding mode controller (SMC) as robust chattering-free control in contact-mode to control the AFM tip during nano-manipulation process for accomplishment of a precise and effective nano-manipulation task in order to achieve the full automatic nano-manipulation system without direct intervention of an operator. The nano-probe is used to push the spherical micro/nano-particle. Nano-scale interaction forces, elastic deformation in contact areas, and friction forces in tip/nano-particle/substrate system are considered. The first control purpose is controlling and positioning the microcantilever tip at a desired trajectory by the control input force which can be exerted on the microcantilever in the Ydirection by a piezo actuator located in the base of the microcantilever. The second control target is PZT-driven positioning stage in AFM-based nano-manipulation in the X,Y in the flat surface. The simulation results show that the designed controllers have been able to make the desired variable state to track specified trajectory during a nano-scale manipulation.