Multistable Soft Actuator for Physical Human-robot Interaction

Collaboration with robots through physical contact offers a more intuitive, natural, and engaging operational experience, showcasing vast potential in the field of human-robot interaction. However, current physical interaction devices, such as collaborative robots and haptic feedback mechanisms, are limited by their singular modes of motion and feedback, hindering enhancements in interaction experiences. Herein, we present a multistable soft actuator capable of driving multimodal shape changes and passively conforming to user touch. This actuator can memorize and maintains any deformation with zero power consumption. Its structural mechanical properties can be dynamically adjusted to produce rich haptic feedback for the user, including changes in shape, elasticity, stiffness, and even sensations of rupture and weightlessness. Structurally, the mechanism consists of a network of pneumatic bistable units in series and parallel configurations, which can switch states under air pressure or external force, achieving extension, contraction, and omnidirectional bending. The input of air pressure can either impede or assist deformation, altering structural stiffness and resulting in varied loading curves. With its high safety in physical interactions, robust operability, and rich mechanical tactile feedback, the multistable soft actuator promises new design directions for physical human-robot interaction devices.