Microrobots less than a millimeter on a side have many potential biomedical applications, including cell manipulation, endoscopy, microorganism studies, targeted drug delivery, cancer therapy, and numerous medical procedures. This project addresses the problem of orienting a free-floating microrobot in three dimensions -- that is, the problem of simultaneously pointing each of three mutually perpendicular edges of the robot in a specified direction. In traditional applications such as spacecraft this is done, for example, using spinning wheels mounted on the body. However traditional approaches are currently infeasible on the submillimeter length scale. This project will demonstrate microrobots capable of precise orientation control using a novel arrangement of vibrating mass actuators. Such microrobots have the potential to transform invasive medical procedures such as endoscopy, micofabrication, and targeted drug delivery.
The primary aim of this project is to demonstrate 3-axis orientation control of a microrobot with onboard actuation. This multidisciplinary project requires advances in noncommutative orientation control theory and microfabrication. Noncommutative orientation control is a new approach to orientation control that takes advantage of the noncommutative property of rigid-body rotations. The control technique generates noncommutative rotations using moving-mass actuators to generate a rapid sequence of positive and negative torques about 2 of the body-fixed orthogonal axes. This sequence causes zero net rotation about those 2 body-fixed axes, while causing a nonzero net rotation about the remaining orthogonal axis. Unlike traditional attitude control technology such as reactions wheels and control moment gyros, noncommutative orientation control can be implemented at the microscale. This project also aims to advance the state-of-the-art in microfabrication by combining lithography-based microfabrication and micro-origami self-assembly.
