Postural adjustment control of a climbing robot having statically indeterminate structure

A postural adjustment control of climbing robot for conical poles, which consists of a position PID control with blind zone and a force release control, is proposed to keep the horizontal posture of the climbing robot and constraint forces between four active wheels and tree in an admissible range. The climbing robot driven by servomechanism without back-drivability can rest on a tree by using its own weight without any energy expenditure. To realize both straight climbing and spiral climbing for conical poles, a postural adjustment mechanism, which consists of two two-link-arm mechanisms with 1 DOF, is needed to drive the steering mechanisms of the active wheels smoothly. Since the posture adjustment mechanism has also non-back-drivability and is a statically indeterminate structure, these sometimes lead to strong constraint forces acting on wheels and caused the out-of-control of the postural adjustment mechanism. The theoretical background is presented and the effectiveness of the proposed postural adjustment control is presented in experimentally.