Modeling and Attitude Control of a Rope Tether-Climbing Robot using a Two-Roller Spiral Propulsion Mechanism

Abstract

We have previously developed a rope tether-climbing robot that is capable of spiral climbing. The climber controls its posture by tilting two rollers against the tether. However, we encountered the problem that the climber rotated around the rope. We attempted to control its posture by constructing a control moment gyro mechanism and a reaction wheel mechanism, but it became clear that angular momentum saturation was inevitable in movements over long time periods. Therefore, to achieve attitude control without angular momentum saturation, we developed a climber robot with a two-roller spiral propulsion mechanism equipped with a derailment prevention mechanism that we developed. We also built an optimal synchronous speed control system for the two rollers. Then, for optimal control, we modeled the frictional forces generated by the rollers, the rolling motion of the rollers, and the ascending motion of the climber. Then, using this model, we constructed an optimal control system for the position and posture of the climber. Climbing experiments verified that attitude control without angular momentum saturation can be realized.