Disturbance Analysis And Adaptive Control Of The Payload Platform For Stratosphere Airship Under Strong Interference

The near space airship is a large inertia system,and the precision control of the large inertial system is a difficult problem,which is also the different characteristic of the airship control from other aircraft.The relative difficulty of spaceships near the airship is mainly due to two fundamental points.one is that the disturbance of the environment is too strong.In addition,the high requirements of the loads on control will increase the difficulty of modeling,analysis and control of system dynamics,which brings a series of scientific problems will to be solved to the discipline of dynamics and control.In view of the low-frequency disturbances of random wind field,atmospheric turbulence and other external environment,according to the atmospheric model and observation data combined with the dynamic equation of the airship,this paper studies the change of the posture and position of the stratosphere airship under the disturbance,and analyzes the statistical and spectral characteristics of the disturbance.Finally,according to the disturbance frequency and bandwidth of the stratosphere airship,the passive isolation method can be used to isolate high-frequency vibration,Meanwhile,the active compensation method is adopted to achieve the low-frequency motion compensation.The research work is summarized as follows:In view of the wind speed series which changes with the time and space and shows the non-linear and non-stationary characteristics,this paper put forward a kind of adaptive model based on Incremental extreme learning machine.Firstly,in order to avoid the random selection of input dimensionality of the Incremental extreme learning machine,the phase space of the wind speed is reconstructed.Secondly,search and optimize the model parameter of the Incremental extreme learning machine to improve the generalization performance of the Incremental extreme learning machine.Finally,the prediction model is established by using the optimized Incremental extreme learning machine,and the results of the online prediction of short-term wind speed are obtained.Nowadays,the simplified atmosphere disturbance model,which is also called engineering model,is widely used when researching the influence of atmospheric disturbance of the stratosphere airship.The stratosphere airship performance influenced by the atmospheric disturbance is mainly analyzed.Firstly,the basic features of the atmospheric disturbance are given,including spectrum properties,disturbance characteristic,scale and strength.Then the simulation model is set up,the wind field is added and the simulation analysis is accomplished on the basic of the model.In order to analyze the high-frequency disturbances change regulation with time caused by airship vibration,based on the NASA Landsat-4 satellite platform vibration test results on orbit,focal plane disturbance force model which is a linear combination of continuous spectrum and harmonics of nonstrictly:integral multiple of fundamental frequency is proposed,which provides credible basis for taking necessary disturbance suppression and compensation measures.In order to solve the disturbance suppression and compensation control problems of the airship payload platform,this paper proposes fuzzy PID controller design method.In the design of fuzzy PID controller,the control principle of fuzzy PID controller is analyzed,fuzzy language variable and membership function are determined,and fuzzy rules,fuzzy reasoning and fuzzy method are formulated.Finally,the fuzzy adaptive PID is applied to the active compensation of the payload platform.The research shows that it improves the dynamic response of second order system and improves the control effect.