Modeling and Control of Active End Effector for the AFM Based Nano Robotic Manipulators

Nanomanipulation using Atomic Force Microscope (AFM) has been extensively investigated for many years. However, control of tip position during nanomanipulation is still a major issue because of the deformation of the cantilever caused by manipulation force. The softness of the conventional cantilevers also cause the failure of the manipulation of relatively large and sticky nano-object because the tip can easily slip over the nano-object. In this paper, an active atomic force microscopy probe is used to solve these problems by changing the cantilever’s flexibility or rigidity through different control strategies in imaging and manipulation modes respectively. During imaging mode, the active probe is controlled to bend up with respect to the interaction force between the tip and samples, thus making the tip response faster and increase the imaging speed. During manipulation mode, the active probe is controlled to bend down with respect to the interaction force between tip and the samples; thus increasing its nominal rigidity to avoid tip slipping over object. A detailed model of the active probe is presented in this paper and the controller designed based on the proposed active probe model is also implemented on the augmented reality system, which is an AFM based nanomanipulation system with both real-time visual and haptic feedback. The simulation results for the control strategies and the preliminary experimental results for the AFM based nanmomanipulation verified the validity of the model and effectiveness of the controller.