A wheel-based cable climbing robot with descending speed restriction

A new wheel-based cable climbing robot which is able to climb up the vertical cylindrical cable on the cable-stayed bridge was proposed. Unlike the previous one, the new designed robot proposed in this paper is composed of two equally spaced modules, which are joined by connecting bars to form a closed hexagonal body to clasp on the cable. The static features of the robot were analyzed and the balanced torque of the mechanism was given. For the present design, it can climb up a cable with diameters varying from 65 mm to 205 mm with payloads below 3.5 kg. A cable with a diameter of 139 mm was selected as an example to calculate the parameters of the robot. For the safety landing in case of electricity broken-down, a gas damper with a slider-crank mechanism is introduced to exhaust the energy generated by the gravity when the robot is slipping down along the cables. The landing system is tested experimentally and a simplified mathematical model is analyzed. Several climbing experiments performed on real cables show the capability of the proposed robot.