sentences:  Each of the robots had to traverse each of these types of ground as well as mounting stairs and negotiating a tunnel.The VIPeR was one of eight in this test, and was one of the most efficient throughout.For mobility, the VIPeR uses a pair of combined wheel/track systems (called the "Galileo Wheel" system, a patented technology by Galileo Mobility Instrument of Israel) that change shape to adapt to terrain, and a "tail" which give it the balance to go up stairs, and turn itself over.