4 DOFs Hollow Soft Pneumatic Actuator-HOSE

This study reports a novel Hollow Soft Pneumatic Actuator (HOSE), which exhibits 4 degrees of freedom (DOFs). The design consists of a central hollow cylinder surrounded by four twisting symmetric chambers. By virtue of their spiral disposition, each chamber produces a diagonal force along the hollow internal cylinder composed of two components: one parallel to the Z axis and the other one to the plane X-Y. Both top and bottom sections of the actuator are reinforced to avoid deformation, essential for optimal function and dexterity of HOSE. Different movements of the actuator are produced by varying the activation combinations of the 4 chambers. They are constructed from thin walled (0.5 mm) Ecoflex 00-30 super soft silicon rubber, enabling HOSE to perform controlled movements with low pressure not exceeding 35 kPa. HOSE exhibits a maximal extension of 230% of its original length, bends up to i) 900 around X axis, ii) 1150 around Y axis, and iii) twists around Z axis with a total range of 350. The paper describes the manufacturing process together with the actuator performance, reporting the range of motion along each DOF related to the internal pressure, volume versus forces and torques produced along each axis.