Structure And Analysis Of A Four-Drive Climbing-Robot

With the rapid development of China’s bridge technology, the number and scale of the cable-stayed bridges have been greatly increased. The cable is the main bearing number of the cable-stayed bridge. Its reliability directly affects the safety of the whole bridge. In order to ensure the safety, the cable should be detected regularly. In the past, it used manual method to detect the cable. The old method is not only inefficient, but also difficult to keep the safe of people. What’s more, it is not practicable since today a cable-stayed bridge may have hundreds of cables. So using industrial robots instead of people to detect the cables has been an inevitable trend. The existing kinds of robot for cable climbing has problems. For example, when works, the diameter that robot can hold can not adjust. In addition, their capability of obstacle crossing is also not good. For all the above reasons, new type of the cable climbing robot was designed and developed. The new robot has the characteristics that the diameter and pressure robot hold on the cable can be adjusted, good obstacle crossing capability, and it also can solve the lock problem.In this paper, the structure design and analysis of the new type of climbing robot is introduced in detail. The robot structure is divided into the frame and the climbing mechanism. The frame is cube shape and the four sides are mounted drive parts which control the robot hold the cable. The climbing mechanism is composed of a four-side carriage and dollies. The robot body mostly composed of aluminum sections and the connecting components, which is beneficial for the rapid manufacture. Through the dynamic analysis of the new type of climbing robot, the conditions of the driving force and clamping force are obtained. According to the design objective and the dynamic analysis, the parameters of the important parts, including the motor and the screw and the compression spring, is calculated out and the models are selected. Through the analysis of the obstacle crossing condition, the main factor affected the robot obstacle capability is obtain, and the parameters of the compression spring is optimized. The paper also put forward that using the nitrogen spring instead of the wire spring to increase the robot obstacle capability. Though comparison, the conclusion that using nitrogen spring can improve the robot obstacle capability is proved.With the finite element analysis software Workbench ANSYS, the static and dynamic analysis of the climbing robot are carried out. The paper proved the structure of the robot satisfied the requirements through the static analysis of the robot important parts include the core shaft and frame. The modal analysis of the robot assemble is carried out, and the natural frequencies and modes of the robot are obtained. By analyzing the results, some parts of the assembly are improved and the overall stiffness of the robot is improved. The paper analyzes the climbing robot’s harmonic responses when it under harmonic force excitation and harmonic displacement excitation. The static and dynamic analysis of the robot ensures the stability and the normal performance of the robot.