A shape memory alloy spring driven soft crawling robot with feet of constant curvature

Soft crawling robots have attracted considerable attentions due to their merits of flexibility, safety, cost, and their unique applications that are not available for the rigid robots. However, poor precision resulting from the strongly nonlinear reconfiguration prevents such soft robots from wider applications. This paper reported a novel SMA spring driven soft crawling robot with feet of constant curvature, and the constant height of the feet during crawling enabled effective alleviation of the nonlinearity of the robotic reconstruction. An analytical static model for the step length of the robot’s crawling gait was built based on 11 independent design parameters, and the influential significance of each parameter was parametrically studied based on the static model. These parameters were then qualitatively classified as strong, medium, and weak factors based on their influences on the theoretical step length of the crawling robot, among which the minimum and the maximum bending angles and the length of the silicone body functioned as the dominant factors. This work provides an efficient approach to the design, prediction, evaluation, and optimization of such soft crawling robots for diverse application surroundings.