Takuya Morinaga

A Path-following Feedback Control Law with a Variable Velocity for a Trident Steering Walker and its Experimental Verification

Abstract This paper presents a path-following feedback control law with a variable velocity for a new type of undulatory locomotor, a trident steering walker. The feedback control law previously presented by one of the authors guarantees asymptotic stability of all the state variables of the locomotor by feedback control, except its position on a path under the precondition that its moving velocity on the path controlled by feedforward is a non-zero constant. In order to make a smooth start and stop, it is necessary for the locomotor to vary its moving velocity continuously. Especially, the slippage between the passive wheels of the locomotor and the floor causes its moving velocity to be reduced so that it cannot move at a desired moving velocity by feedforward control. Therefore, we modified the feedback control law previously presented. In the modified feedback control law, all the state variables of the locomotor are controlled by feedback and their asymptotic stability is guaranteed. Furthermore, the deviation of its moving velocity from the desired moving velocity because of the slippage between the passive wheels of the locomotor and the floor is compensated and converges to zero by a new feedback control loop in which its moving velocity on the path is variable. We developed an experimental apparatus of the locomotor and verified the effectiveness of the feedback control law with a variable velocity.