To introduce the force control for an uneven terrain walking robot such that it effectively sets the suitable contact pressure of its supporting legs and is able to change from support to swing legs smoothly, the force control for ParaWalker-II, serial/parallel hybrid mechanism that is connected between two frames and contacts ground at three points, is proposed. With this method, the entire leg-drive mechanism acts as a 6-axis force sensor; and the force and moment can be calculated from the changes of each joint angle such that sensors at the ends of the leg are not necessary. Furthermore in the paper; force control and position control can be chosen for each direction in order to smoothly walk on uneven terrain. Smooth contact with the ground by the swing-leg and the changing from swing to support leg is verified through experiments using this force control and measurement method.

A walking robot that has high ground adaptability and the ability to perform various tasks would be extremely desirable in many fields. It can move efficiently in an outdoor environment and on uneven terrain such as stairs, as well as perform tasks. In this paper, for a six-legged uneven terrain walking robot with two body segments, we examine the number of degrees of freedom, movement performance, stability on uneven terrain, and work performance. In addition, we examine the arrangement of the degrees of freedom suitable for practical uneven terrain work by this type of robot. We also propose that a walking robot with an extra leg extension mechanism and a 6-DOF between the body segments is effective. We adopt this design to ParaWalker-II, which we had previously developed, and verify the effectiveness.