Musculoskeletal actuators with programmable morphology and tunable dynamics

Inspired by natural species exploiting morphological changes to adapt to complex environments, morphable robots have emerged as a frontier of robots with embodied intelligence, particularly for multimodal and cross-domain locomotion. However, the development of small-scale flexible actuators with dual programmability in morphology and dynamics remains elusive, hindering miniaturization of untethered morphable robots. Inspired by biological musculoskeletal systems, we present artificial musculoskeletal actuators constructed with serially connected morphable skeleton modules and stiffness-tunable muscle modules, enabling programming of both morphology and dynamics. The muscle module exploits a multilayer PDMS-based dielectric elastomer and an electrothermally actuated shape memory polymer, allowing modulation of resonant frequency, resonant vibration amplitude, and actuation force. Geometrically sophisticated musculoskeletal actuators are constructed to reproduce complex dynamic behaviors of species like woodpecker and scorpion. Demonstrations of an untethered sugar glider-inspired multimodal small-scale robot and a morphable small-scale robot with quadruped and humanoid locomotion modes suggest promising applications of proposed actuators.