A Reconfigurable Soft Actuator with Tunable Deformation and Stiffness

Currently, it is challenging for a soft actuator to simultaneously achieve tunable deformation and maintain high load capacity. To address this issue, this paper presents a reconfigurable soft actuator with tunable deformation and stiffness (RATDS). The soft actuator consists of a skeleton and a thermoplastic polyurethane (TPU) skin. The skeleton is composed of two shapes of cavity units with particles filled and a polyethylene terephthalate (PET) sheet. It can realize various deformations with different assembly models of the cavity units under vacuum pressure. Stiffness variation is achieved by increasing vacuum pressure, causing the cavities to shrink and leading to particle jamming. The convenient manufacturing and assembly methods are demonstrated. The finite element analysis (FEA) simulations and experiments show that the actuator's deformation can transition from 2D bending to 3D twisting and multi-direction deformation with different assembly models, respectively. Durability experiments confirm its functionality even after 5000 cycles. The actuator exhibits fast response time (0.35 s) excellent stiffness enhancement (from 0.019 N mm⁻¹ (0 kPa) to 0.219 N mm⁻¹(−40 kPa)) and good tip force (averaging 3.85 N). Furthermore, it shows good grasping capabilities (maximum loads 2110 g (three-finger gripper) and 700 g (single-finger gripper)) and crawling capability (10.7 mm s⁻¹).