Abstract
This paper analyzes the motion of a multi-limbed robot in contact with other objects or the ground at multiple points. A limb is defined as a serial link mechanism, such as an arm, a leg, a finger. The motion of the robot is restricted if the multiple contact points are held stationary. In general there are singular postures at which the motion of the robot has an additional degree of freedom. Contact at multiple points also causes the restriction on their sliding directions when they slide. This paper proves that when the robot is at the singular posture, the sliding directions are more restricted. We also show that the closer the robot approaches the singular posture, the more difficult the contact points slide in the directions infeasible at the singular posture. Sliding analysis is important not only for sliding control but also position and force controls of the limbs. We developed a quadruped robot which can take various postures, e.g. lying on the ground and standing on the knees. The motion of the quadruped robot is analyzed as an example of a multi-limbed robot in multi-point contact.
