Nano-robotic manipulation using a RRP nanomanipulator: Part B - Robust control of manipulator's tip using fused visual servoing and force sensor feedbacks

Due to lack of position and velocity feedbacks in MM3A nanomanipulator, a fused vision/force feedback robust controller has been recently designed by the authors. This second paper in the series presents the optimal utilization of the visual servoing and force sensor feedbacks for use in the nanomanipulation tasks discussed in the first paper (Part A). More specifically, the visual servoing and force feedback structures are investigated through extensive simulations in order to reveal issues in practical implementation. For this, a set of numerical simulations is performed to demonstrate the effectiveness of utilizing just vision feedback as well as force feedback only, at both macro and microscale. It is shown that although each feedback module could provide reasonably accurate results at either macro or microscale, precise positioning of such nanomanipulator requires employment of both modules with a proper (optimal) switching strategy. This paper extends our previously introduced robust controller for nanomanipulator positioning and offers a novel switching framework to be used between vision feedback and force feedback modules. Utilizing a soft switching function, the problem of jump in the actuator force during fused vision/force control of the nanomanipulation can be overcome. Following the development of the soft switching approach, numerical simulations are used to verify the positioning performance and effectiveness of each switching strategy.