The Inchworm is a biologically-inspired mobile robot whose movement is similar to that of an inchworm caterpillar. It consists of a three degree-of-freedom main body which can flex and extend to propel itself, along with electromagnets at each end of the body which provide the anchoring force for the motion. The Inchworm can operate on steel surfaces of arbitrary orientation, i.e. it can climb vertical steel walls and crawl across a steel ceiling using the electromagnets to attach itself to the surface. The Inchworm can also make transitions between surfaces, allowing it to navigate autonomously in unknown environments.