Plate-Springed Parallel Elastic Actuator for Efficient Snake Robot Movement

Abstract

The design methodology of a plate-springed parallel elastic actuator (PSPEA) for the efficient movement of planar snake robots is presented. The stiffness, which refers to the relationship between the resilience moment and the joint angle, of the plate spring was first designed using a rigid body spring model. The modeled stiffness was then verified via a simple test rig. Combinations of spring stiffnesses that minimize the energy consumption of each joint at different velocities were obtained using dynamic simulation. Experiments using a planar six-link PSPEA-based snake robot were performed via sensors installed in the servomotors to measure torque and speed, and a motion-tracking system was utilized to measure the moving distance. True efficiency was evaluated using the cost of transport criterion, which was later compared with the dynamic simulation results. Despite its compact design, it was observed that the proposed PSPEA improved the energy efficiency of the snake robot by a maximum of approximately 50%.