Velocity Control with Gravity Compensation for （速度与重力补偿控制）.pdf

Advanced Robotics 25 (2011) 1007–1028 brill.nl/ar Full paper Velocity Control with Gravity Compensation for Magnetic Helical Microswimmers Arthur W. Mahoney a,∗ , John C. Sarrazin b , Eberhard Bamberg b and Jake J. Abbott b a School of Computing, University of Utah, Salt Lake City, UT 84112, USA b Department of Mechanical Engineering, University of Utah, Salt Lake City, UT 84112, USA Received 25 June 2010; accepted 11 August 2011 Abstract Magnetic helical microswimmers, which swim using a method inspired by the propulsion of bacterial flag- ella, are promising for use as untethered micromanipulators and as medical microrobots. Man-made devices are typically heavier than their fluid environment and consequently sink due to their own weight. To date, methods to compensate for gravitational effects have been ad hoc. In this paper, we present an open-loop algorithm for velocity control with gravity compensation for magnetic helical microswimmers that enables a human operator or automated controller to command desired velocity intuitively, rather than directly con- trolling the microswimmer’s orientation and rotation speed. We provide experimental verification of the method. © Koninklijke Brill NV, Leiden and The Robotics Society of Japan, 2011 Keywords Microrobot, helix, screw, magnetic, wireless, untethered 1. Introduction Untethered biomedical microrobots are a topic of considerable research. Micro- robots have the potential to radically transform many medical procedures by operat- ing in hard-to-reach locations of the body, performing tasks such as targeted therapy (e.g., drug delivery, hypertherm