Ferromagnetic soft smart structures exhibit great potential for a multitude of applications in the fields of biomedical, automation, and industry. However, the reported ferromagnetic soft-robot structures are mainly focused on achieving multi-mode response, motion control, and improving sensing performance. Unfortunately, those can only react to an externally applied field and are unable to provide feedback regarding their own deformation state during the control process, impeding their intelligent, integrated, and multi-functional development.
In this study, we have combined distributed optical fiber and programmed 3D printing magnetic domain technology, to investigate a distributed sensing-actuation integrated ferromagnetic soft smart structure with programmable deformation, real-time shape reconstruction, and magnetic navigation capabilities. In order to predict the deformation and morphology of the magnetic soft-robot structure, a magneto-mechnaical coupling model is constructed, and the deformation state is duplicated according to the strain signal of embedded optical fiber.
Our experimental and simulation results demonstrate that the various designed structures, such as the V-shape, N-shape, M-shape, and entrainment structure, can reconstruct their deformed shapes in real-time with a delay of only 30ms between applying the driving field and reconstructing the deformation, and that they have high repeatability and stability. The mean and standard deviation of the errors between the reconstruction and the experiment were -0.16±0.06 [mm], and -0.084±0.04 [mm], respectively. We further showcase the magnetic navigation drive and closed-loop deformation shape control capability, which allow soft robots to function effectively in demanding conditions (e.g., confined or opaque areas). Due to the integration of sensor and actuator, as well as the real-time reconstruction of the shape sensing, our ferromagnetic soft robot exhibits bionic sensing capabilities, potentially addressing the challenges and unmet demands in the field of soft robotics.
 

Integrated sensing-actuation, Soft robots, Magneto-active materials, Programmed 3D printing.