Abstract: [Objective] In order to scan the wooden column of ancient buildings by X-ray, a climbing robot is developed.[Method] Firstly, The structure of the encircling-rotating mechanism of the climbing robot is presented, and the process of the robot climbing along the wooden column is introduced. At the same time, the structure of the control system is completed, which adopts wireless remote and has the hardware structure based on the bus. Then, the coupling PD algorithm for the horizontal translational joints and the coupling sub-PI synchronization control algorithm for vertical translational joints are researched respectively, and the speed control of the rotating joint is also realized. Finally, the function test and control effect analysis are carried out through the CT scanning climbing robot.[Result] In the process of climbing along the wooden column, the contact detection force of the horizontal translational joints from the initial position to the contact state is set to 50 N. Setting value of clamping force to 5 000 N, the precision of the actual clamping force is up to 96.2%, and the load capacity of the robot is more than 60 kg. The average displacement error of the vertical translational joints is less than 0.5 mm through synchronous control. When angular velocity is set at 3(°)·s^-1, the maximum angular velocity of the rotating joint is 0.116(°)·s^-1 and the average error is 0.003(°)·s^-1, which all satisfy the requirements of CT scanning.[Conclusion] The climbing robot can climb up or down along the wooden column, and the CT scanner revolves round the wooden column 360° through the rotating body. Then, the image of the cross section is reconstructed to evaluate the internal characteristics and the health status accurately.

Key words: climbing robot, CT scanning, ancient building, wooden column