Motion characteristics of untethered swimmer with magnetoelastic material

Cable-less micro-robots have exhibited promising potential for conducting tasks in small and constrained environments through remote controlling approaches. Soft robots formed by magnetic composites have drawn rising attention, and have demonstrated their capability to be wirelessly controlled in both dry and wet working environments. This paper presents a swimmer propelled by its undulatory deformation using a magnetoelastic composite material. The swimmer can move freely on water surface driven through magnetic field generated by 3D Helmholtz coils, allowing forward and backward motion as well as steering with different velocity ranging from 0 to 14.9 mm s−1. To further study the characteristics of the swimmer, the force and torque equilibrium equations were established, and deformation of swimmer in response to different magnetic field was analyzed and described. The relationship between the parameters of magnetic field and the properties of the swimmer was obtained through analytical calculation, finite element modeling (FEM) and experiments. Furthermore, a closed-loop controlled system was developed to allow automatic path tracking and PID control of the swimmer, leading to distance errors and steering errors within ±0.36 mm and ±18.2° respectively. The swimmer and its mathematical model have suggested effective control through changing the parameters of external magnetic field. The swimmer may serve as soft surgical robots and drug delivers for biomedical and healthcare applications.