Abstract:Microrobots have a number of potential applications for micromanipulation and assembly, but also offer challenges in power and control. This paper describes an uncalibrated vision-based control system for magnetically actuated microrobots operating untethered at the interface between two immiscible fluids. The microrobots are 20 μm thick and approximately 100-200 μm in lateral dimension. Several different robot shapes are investigated. The robots and fluid are in a 20 × 20 × 15 mm vial placed at the center of four electromagnets. Pulse width modulation of the electromagnet currents is used to control robot speed and direction. Given a desired position, a controller based on recursive least square estimation drives the microrobot to the goal without a priori knowledge of system parameters such as drag coefficients or intrinsic and extrinsic camera parameters. Results are verified experimentally using a variety of microrobot shapes and system configurations.
Microrobot systems have demonstrated potential in the areas of manipulation, assembly, and therapeutic tasks at the microscale. This paper investigates uncalibrated visual servoing of microrobot devices in a fluidic environment. Planar actuation is achieved with four electromagnets, and both pointto-point motion and trajectory following are demonstrated. The unique contribution of this paper is the implementation of a dynamic recursive least squares estimation algorithm that is used to control the device as it follows a desired path without any calibration or training steps. Tracking accuracy on the order of 1.6 pixels (10.5µm) is demonstrated for a 200µm diameter microrobot. Initial trials successfully achieved micromanipulation of both 50 and 200µm glass beads.
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