In this thesis are investigated the gait control problem and the path planning problem of a quadruped walking robot which are essential problems to be solved to endow the legged robot with the autonomous walking capability on uneven, irregular terrain.
In our solution approach for the gait control problem, a hierarchical strategy for the crab gait control is proposed. We present a procedure for finding an optimal sequence of the body movement which maximizes the gait stability margin. A measure for the selection of a swing-leg sequence, called the traversability, is also introduced. It is shown by simulation results that the proposed gait algorithm is efficient and meaningful in view of generalizing the crab gait algorithm and enhancing the terrain adaptability.
Unlike the collision-free path planning problem of wheeled robots, the path planning problem of legged robots has unique aspect from the point of view that legged robot can deal with obstacles in the manner of not only avoiding collision with pole-type obstacles but also crossing over hole-type obstacles. Furthermore, the gait condition together with the terrain condition should be considered in the process of the path planning for legged robots. Thus the path planning problem of legged robots is different and usually more complex than that of wheeled robots.
In this thesis, we propose a novel method for the path planning of a quadruped robot on a known, uneven terrain. Under the assumption of a level-walking crab gait, we transform the planning problem in 3-D workspace into the 2-D planning problem on the configuration space of the robot, in which the obstacles are also transformed into the configuration space in consideration of their relevant properties in 3-D workspace.
To make our approach systematic and general, a new concept of the artificial thermal field is introduced. The artificial thermal field is constructed numerically over the discretized configuration space using a proposed equilibrium equation and a feasible path is sought in the field. To verify the efficiency of the proposed approach, remarkable simulation results are provided.
