Modeling Locomotion in a Segmented Soft Robot using Planar Discrete Elastic Rods*

Modeling soft robots that move on surfaces is challenging from a variety of perspectives. Recently Bergou, et al. introduced a numerically efficient formulation of Discrete Elastic Rods (DER) based on discrete differential geometry. In this talk, we describe a simplified planar version of Bergou et al.’s theory and show how it can be used to model soft robots that are composed of segments of soft material folded and bonded together. To show the efficacy of DER, the formulation is used to describe and analyze the dynamics of a prototype caterpillar-inspired soft robot. The robot consists of six segments of a shape memory alloy actuated soft material. By controlling the timing and sequencing of the actuators, locomotion can be achieved by exploiting stick-slip friction and the variation in the normal force exerted by the ground plane on each contacting actuator. Successful modeling of the robot also entailed the development and implementation of procedures to prescribe the parameters for components of the soft robot. After describing these procedures, we discuss the comparison of our calibrated model to the experimental behavior of the caterpillar-inspired soft robot. The extension of the DER modeling to other soft robot designs will be discussed.