Introducing Mag-Nets: Rapidly Bending Electromagnetic Actuators for Self-Contained Soft Robots

Abstract

Present electromagnetic soft actuators rely on external magnetic fields or power supplies, while the very few that operate autonomously produce weak actuating forces, limiting their practicality. This work introduces a novel current-controlled electromagnetic actuator that employs copper coils and permanent magnets to produce substantial driving forces. The actuator can serve as a building block for independently controlled actuating networks to develop sophisticated self-contained soft robots and grippers. The design, inspired by fast pneu-net (fPN) actuators, ensures minimal bending resistance from the silicone body and, thus, allows high-speed bending motions. Two applications of the prototype actuator are studied; a two-fingered soft gripper realizing bending speeds of up to 1491 °/s and maximum grasping force of 1.19 N, and an entirely self-contained crawling soft robot utilizing friction anisotropy to generate forward locomotion. A lumped-element model is developed and validated experimentally to describe the dynamics of the gripper's soft finger. Pick-and-place tasks on various targets, and tests on the crawling robot demonstrate, overall, the effectiveness of the developed actuator. The uniqueness of Mag-Nets, lying in their control simplicity, enhanced capability and cost-effectiveness, sets the foundations for a new design approach for soft robots and grippers.