Abstract: We have created an inchworm robot capable of the two-anchor crawl gait on level ground and inclined plane. The main novelty is in the design of the inchworm: (1) three-part body that is 3D printed and actuated by two servo motors to allow a looping and lengthening action, (2) passive friction pads to anchor the feet, each of which may be disengaged using a servo motor actuated lever arm, and (3) modular body and electronics. The robot is about 2 feet (61 cm) in length, has a mass of about 4 kg, and uses an open-loop controller to achieve steady crawling gait. The inchworm robot achieved a speed of 2.54 cm?s?1 on level ground as well as on an incline plane of 19?. The energy usage as measured by the Mechanical Cost of Transport (a non-dimensional number defined as the energy used per unit weight per unit distance moved) is 3.34. Our results indicate that simple robotic designs that copy the basic features of natural organisms provide a promising alternative over conventional wheeled robots.

Key words: inchworm, bioinspiration, two-anchor crawl gait, 3D printing, sliding locomotion, cost of transport