Design and Control of a Modular, Untethered Soft Origami Robot Driven by SMA Coils

Soft robots show advantages in flexibility and safe interaction compared with traditional rigid robots. The modular design of soft robots further improves their reconfigurability and easy maintenance. This article presents a soft modular robot based on a rectangular origami structure, which can achieve untethered, controllable, and diverse motions. The single robot module is designed with actuation by four shape memory alloy coils and attitude perception based on an inertial measurement unit sensor. The module has an option for the use of internal battery or external power, can be wirelessly charged, and can be used as a flexible sensor to sense forced deformation. A model-free controller based on the cross-coupling concept is also proposed to control the attitude angles of the single module, the accuracy and robustness of which are verified by extensive experiments. The strong independence of the origami module in actuation, sense, and control facilitates reconfiguring various robots, such as a crawling robot, a gripper, and a robotic arm, and programming their motions. These robots can be quickly assembled or disassembled by magnetic attachments and will provide solutions for variable work assignments.