Research On Dynamic Control And Experiment Of An Aircraft Skin Inspection Robot

The problem of aircraft skin damage inspection is related to the safety of aircraft flight,and has attracted more and more attention.In this paper,the mechanical structure has been improved on the first generation of the aircraft skin inspection robot designed by our laboratory to make it more suitable for movement on the outer surface of aircraft skin.On this basis,theoretical research and comprehensive experiments of robot motion are carried out.Firstly,the mechanical structure of an aircraft skin inspection robot with vacuum adsorption double-frame is introduced,and the motion gaits of the robot on the surface of the aircraft skin are analyzed.A multiple input multiple output dynamic model was established for the single-step motion control of the aircraft skin inspection robot on the surface of the aircraft skin.Secondly,according to the dynamic model of the robot,a control method based on sliding mode control strategy is designed.An adaptive RBF neural network is used for estimation and compensation of the uncertainty and friction nonlinearity in the dynamic model.By using hyperbolic tangent sliding mode function,the system chatter caused by switching sliding mode function is suppressed.The Lyapunov function is constructed to prove the stability of the system.The simulation results show that the proposed control strategy has good tracking performance in the presence of unknown model information,friction nonlinearity and unknown disturbances.Then,the backstepping control strategy of the robot with output constraints is designed.An adaptive fuzzy system is used to compensate the uncertainties related to the system states.An adaptive law is designed to estimate the upper bound of the unknown disturbance,and a robust compensation term is introduced to reduce the influence of the unknown disturbance on the system.Considering that there are state variables that are difficult to be measured in the actual system,a high gain state observer is designed to estimate it.The stability of the system is proved by constructing Lyapunov function.The simulation results show that the designed controller can track the desired trajectory accurately.Then,in order to control the motion and monitor the status of the robot,the control software of the robot's DSP slave computer and the human-computer interaction software based on embedded Linux are designed,and the communication protocol and data parsing protocol between upper and lower computers are standardized.The control software of the DSP slave computer mainly includes the robot motor driver,serial communication program and ADC driver.Human-computer interaction software runs in the QT environment of embedded Linux platform,which is used to complete the portable manipulation of the robot and display the state parameters of the robot.Finally,the experimental research on the motion control of the aircraft skin inspection robot is carried out,and the verification of human-computer interaction software and robot adsorption stability was completed.