When a wheeled robot moves inside a tapered thin-walled deep cavity cylinder, how to reduce the coaxial deviation between the robot and the cylinder parts is crucial for improving machining accuracy. However, the wheeled robot system using the distributed cylinders as the variable radius mechanism has nonlinear, time-varying, and complex frictional characteristics, which make precise control of coaxial motion deviation extremely difficult. Therefore, this article proposes an adaptive motion control method based on the variable domain fuzzy control theory to improve the precision of robot motion radial displacement and yaw and pitch angle control precision. Firstly, the tree-like kinematic model of the wheeled robot walking mechanism is formulated, and a pose calculation method is proposed. Then, the adaptive motion control method is proposed, and a joint simulation system based on Simulink and Adams is established to evaluate the effectiveness of the method. Finally, the cylinder internal motion control experiments are implemented by using a robot prototype. The results show that the proposed adaptive motion control method can reduce the internal motion deviation of the robot and ensure that the radial displacement deviation of the robot is ≤±1 mm and the yaw and pitch angle deviation are ≤±1°.