Modular Volumetric Actuators Using Motorized Auxetics Volume change has become a critical actuation method in robotics. However, the need for fluid flow or thermal processes to generate volume changes limits the durability, speed, and efficiency of these actuators. In this paper, we develop a new electromechanical actuator that volumetrically expands. By combining auxetic materials with a servo, we produce a simple isotropically expanding actuator that can be modularly composed. We discuss the symmetry considerations in selecting an appropriate auxetic framework for our actuator, eventually choosing a doublelayered polyhedral auxetic design. Characterization shows that a single actuator can expand in radius to 119% of the original size and generate 90N of force, while maintaining a small package and a speedy expansion  contraction cycle. Finally, we demonstrate the modularity of our actuators by linking three actuators to create a vertical tubecrawling robot. The small package and fast cycle time of our system highlight how viable these electromechanical volumetric actuators can be as an important actuator modality.

Actuation and stiffening in fluiddriven soft robots using lowmeltingpoint material Soft material robots offer a number of advantages over traditional rigid robots in applications including humanrobot interaction, rehabilitation and surgery. These robots can navigate around obstacles, elongate, squeeze through narrow openings or be squeezed  and they are considered to be inherently safe. The ability to stiffen compliant soft actuators has been achieved by embedding various mechanisms that are generally decoupled from the actuation principle. Miniaturisation becomes challenging due to space limitations which can in turn result in diminution of stiffening effects. Here, we propose to hydraulically actuate soft manipulators with lowmeltingpoint material and, at the same time, be able to switch between a soft and stiff state. Instead of allocating an additional stiffening chamber within the soft robot, one chamber only is used for actuation and stiffening. Low Melting Point Alloy is integrated into the actuation chamber of a singlecompartment soft robotic manipulator and the interfaced robotic syringe pump. Temperature change is enabled through embedded nichrome wires. Our experimental results show higher stiffness factors, from 9xe2x80x9312 opposing the motion of curvature, than those previously found for jamming mechanisms incorporated in separate additional chambers, in the range of 2xe2x80x938 for the same motion.