A self-reprogrammable soft pneumatic valve for fast, switchable, and complex actuation in time and in space.

Despite the exciting advancements in the field of soft robotics, the autonomous actuation of soft robots is still difficult to attain. In this work, we propose a self-reprogrammable soft pneumatic valve that provides a fast and complex output in time and space in response to a slow volume input. The valve consists of multiple interacting shells with complementary roles that enable switching between actuation modes. The monostable shells provide actuation to soft robots, and the bistable shells regulate the actuation mode. Upon the snapping of the bistable shell, the multiple-shell valve reversibly switches from synchronous to sequential actuation mode, hence allowing multi-modal actuation. Performance metrics of the shells are experimentally investigated and numerically mapped through a parametric study that guides the design of the valve. The functionalities of the valve are showcased in a soft-legged robot that can switch from grasping to crawling and in a humanoid soft robot that can switch between complex choreographies. Our self-reprogrammable multiple-shell valve possesses a higher level of intelligence than existing soft pneumatic valves, paving the way for fully autonomous soft robots.