Walking and running of the quadruped wall-climbing robot

The development of a wall climbing robot which is able to move over the surface of “3-dimensional terrain”, a terrain including floor, wall, ceiling of any kinds of structures with agility and terrain adaptability is strongly demanded in many industries. The conventional wall-climbing machines were far from fulfilling the demand, the authors thus have been developing a wall-climbing robot with four-terrain-adaptive legs and basic mobilities were already demonstrated by the manufactured prototype model NINJA-I. However, as there are almost no examples of wall-climbing quadrupedal animals and conventional machines, the gait control method specific for the quadruped wall-climbing is not at all known by now. As the first step to consider a general gait problem of a quadruped wall-climbing robot, this paper investigates a gait of the robot on a vertical and flat wall. The gait is analyzed with the criterion to maximize the locomotion speed under the constraints of predetermined conditions of the supporting-legs position, order and phases of swing legs to prevent turn over motion. As a result of the analysis, the optimal standard gait, named “Wall Gait”, is shown to maintain foot posture of Λ shape and moves the leg in the order of leg1-leg2-leg4-leg3 in static walk and the order of “pace” in dynamic walk