Initial design and analysis of a helix cable detecting robot

To inspect the inner broken wire condition of the helix cables of cable-stayed bridge, a helix cable detecting robot is proposed in this study. This robot is constituted by a driving trolley and upper and lower support hold devices. The driving trolley and support hold devices are connected by joint components and oppositely arranged along the cable. A climbing device and a magnetic absorption device are designed in the driving trolley, while, the climbing device can enable the trolley to arbitrarily rotate around to adapt water guide line with different screw pitch. Moreover, to ensure the robot to return ground safely, a centrifugal speed regulation method is proposed. By this method, the safe recovery of robot in electrical fault is realized. Theoretical analysis and experimental results suggest that, the mechanism is able to carry 2 kg load to rise steadily and slide down at automatically limiting speed along helix cable at inclining angle of 30° - 90°.