Design and Characterization of a 3D printed Wave Spring for use in a Flexible Robotic Arm

This paper proposes the use of wave springs as structural segments for soft, flexible robotic arms. Conventional robotic arms are limited in their use within confined spaces due to the lack of maneuverability and safety. Soft robotic flexible arms, inspired by biological counterparts such as octopus arms, snakes, and elephant trunks, are a solution for this limitation. They provide flexible limbs with redundant degrees of freedom that allow for bio-inspired extension, retraction, and bending motions. In this paper, we propose the use of a 3D-printed, soft wave spring as the skeletal structure for a flexible robotic arm. The design and fabrication of the wave spring are presented. The wave spring is characterized in terms of bending and blocked force performance. The wave spring is proposed to be actuated via tendons, and a kinematic model is developed to describe its motion. The motion of a wave spring segment was evaluated using a prototype setup. The results validate the applicability of a novel tendon-actuated wave spring actuator for use in flexible robotic arm applications. Experimental results show that a single wave spring actuator achieves a maximum compression ratio of 43% at 199.8 N, and a maximum bending angle of 29.3° at 17.25 N.