UC Berkeley

Magnetically driven centimeter- and millimeter-scales robots have unique advantages in applications requiring wireless operation, fast response, and precise control. Magnetic fields can be generated externally to actuate and control robots without the need for onboard power, making them particularly suitable for operation in confined and complex environments, including biomedical applications. This dissertation investigates magnetic actuation and control strategies for untethered robots, with a focus on programmable magnetic fields to achieve versatile and controllable robotic motions.Three representative robotic systems of different scales and functionalities have been developed driven by externally generated magnetic fields. First, a magnetic platform using an array of electromagnetic coils has been built to power and control untethered micro flying robots with a wingspan of 20.5 mm. The constructed magnetic field in space can be arranged with high-degree-of-freedom with a multi-channel, multi-coil system. Experimental results demonstrate several key flight capabilities, including takeoff and basic attitude controls. The second system centers on a new class of magnetically actuated soft robots based on a bioinspired “bone-in-flesh” architecture at the centimeter scale (~10 cm). By embedding rigid magnets within flexible polymeric structures, the system can have rapid and controllable deformations under externally applied magnetic fields. Theoretical modeling, numerical simulations, and experiments are conducted to analyze the system structural deformation as design guidelines for soft magnetic actuators with non-uniform stiffness. The third system is a millimeter-scale untethered robotic platform to achieve surface locomotion modes under a single-axis alternating magnetic field, including crawling, rolling, and spinning. By leveraging both magnetic alignment torque and gradient-induced force, the programmable motion controls of different operational modes have been achieved based on either 3 or 2 mm in diameter micro robots. 2 Experiments toward practical applications, such as the navigation in confined channels, enhanced diffusion for drug delivery, and in vitro thrombectomy, have been demonstrated to highlight the potential in biomedical settings.