LAUSR

A novel variable friction mechanism is presented for a soft robot that can both move on a flat smooth surface and crawl on a steep smooth surface. First, the variable friction mechanism of the head and tail parts is presented, which can achieve three different frictions (low, medium and high) using SMA3 wire and an electromagnet. In addition, the lightweight and simple structures of both the body and steering parts are demonstrated. Second, according to the variable friction mechanism and the crawling locomotion sequence of the body, head and tail parts, the crawling performance is tested. When the head and tail parts switch between low and medium friction, the soft robot's maximum inclined surface angles for climbing up and down are 6° and 12°, respectively; the corresponding values are 12° and 42°, respectively, when the head and tail parts switch between high and medium friction. Finally, the steering ability of the soft robot is confirmed to be due to the tunable high friction. In conclusion, a novel three-state switch mechanism using a shape memory alloy and an electromagnet for variable friction is presented, which can help the soft robot achieve crawl and steer.