Stochastic Control for Orientation and Transportation of Microscopic Objects Using Multiple Optically Driven Robotic Fingertips

The effect of Brownian motion on maneuvering of micro-objects in a fluid medium is one of the fundamental differences between micro-manipulation and robotic manipulators in the physical world. Besides, due to the limitation of feasible sensors and actuators in micro-manipulation, current control techniques for manipulation of micro-objects or cells are mostly dependent on the physical properties of target micro-objects or cells. In this paper, we propose the first stochastic control technique to achieve simultaneous orientation and transportation of micro-objects with Brownian perturbations. Several micro-particles which are optically trapped and driven by laser beams are utilized as fingertips to first grasp a target micro-object. Cooperative control of robot-assisted stage and the fingertips is then performed to achieve the control objective, in which the target micro-object is transported toward a desired position by using the robot-assisted stage, and at the same time, it is oriented toward a desired angular position by using the fingertips. This paper provides a stochastic control framework for simultaneous orientation and transportation of micro-objects with arbitrary types in the micro-world, and thus bringing micro-manipulation using optical tweezers closer to robotic manipulation in the physical world. Rigorous mathematical formulation and stability analysis for simultaneous orientation and positioning feedback control of micro-objects in the presence of the stochastic perturbations are derived, and experimental results are also presented.