Wall Gait : A Standard Gait for the Quadruped Wall-Climbing Robot

The development of a wall-climbing robot which is able to move on a "3-dimensional terrain", including floor, wall, ceiling is in high demand in many industries. Thus the authors have developed a quadruped wall-climbing robot, named "Ninja". However, the gait control method specific for the quadruped wall-climbing robot is not at all known yet. As the first step toward consideration of a general gait problem of a quadruped wall-climbing robot, this paper investigates the standard gait on a vertical and smooth wall. The gait is analyzed with a criterion that maximizes the locomotion speed under the constraints which mainly prevent the turning over motion of the robot. As a result, the optimal standard gait, named "wall gait", is shown to maintain foot arrangement of A shape and to move the legs in the order of front-left, rear-left, front-right, rear-right, in static gait and the order of "pace" in dynamic gait. Wall gait realizes fast locomotion and stable sucking motion using a specific motion generated by its own weight when only two legs are sucking the wall.