Abstract: According to the functional requirements of autonomous mobile mechanism for aircraft assembly, an autonomous mobile mechanism is designed which consists of two frames, eight legs and vacuum suction system. Its degrees of freedom are analyzed based on screw theory, which proves the mechanism can realize 5 degrees of freedom required for normal direction automatic drilling. The calculation method and an example of inverse kinematics are provided, which can calculate the displacement of legs from initial to desired normal direction. The calculation is sample and can be used to the online control algorithms. The prototype of autonomous mobile mechanism is developed, driven by 12 motor. Through the third party testing, the system motion accuracy and precision of drilling is verified. The results show that the normal direction adjustment accuracy is less than 0.2º, which meets the engineering requirements not more than 0.5º; the position precision is not more than 0.3 mm and repeatability precision is not more than 0.2 mm, under different angle. The mechanism can meet the requirements of stiffness, accuracy, and bearing capacity.

Key words: Aircraft assembly, Inverse kinematics, Parallel mechanism of autonomous mobile, Screw theory