Rare-Earth-Free Wave-Driven Artificial Muscles: A Distributed Magnetic Phase Architecture Based on Iron Nitride Microstructures

This paper proposes a rare-earth-free wave-driven artificial muscle architecture in which magnetism is repurposed as a distributed phase-control mechanism rather than a force source. Iron–nitride-based magnetic microstructures are embedded within compliant actuator bodies to modulate local stiffness, shape wave propagation, and stabilize phase dynamics. A minimal physical model based on stiffness modulation and weakly coupled phase oscillators links magnetic anisotropy to effective stiffness control, group-velocity tuning, and distributed phase synchronization. Order-of-magnitude energy considerations demonstrate that modest magnetic energy densities achievable with abundant Fe–N materials are sufficient for phase regulation without reliance on rare-earth magnets. The proposed architecture is compatible with scalable manufacturing techniques and is intrinsically resilient to supply-chain constraints, establishing a general design principle for post-rare-earth actuation systems in soft robotics and related fields.