Research On Self-tuning Fuzzy Control Of The Atmospheric Pressure Simulation System

The Atmospheric Pressure Simulation System (APSS) is an important device inHardware In the Loop Simulation (HILS) of aircraft, producing pressure signal to imitatethe altitude and airspeed. With the development of HILS, lower pressure and betterdynamic are required. The features of the APSS are discussed in this article, and aself-tuning fuzzy control strategy is proposed against nonlinearity and asymmetry of theAPSS. Theoretical researches and experiments on the strategy are conducted, whose resultsshow that the faster response of lower pressure is achieved.Firstly, the structure and working principle of the APSS is expounded. On basis ofcombining vacuum technology pneumatics theory the mathematics model of the APSS isdiscussed. Then, computer digital simulation on the system is implemented to analyze thefeatures of the APSS. Nonlinearity and asymmetry existed in the APSS is discovered,which have bad effects on its performance.Secondly, due to the nonlinearity of the APSS and the difficulty in obtaining accuratemodel, it is not suitable to utilize classic control in the APSS. A self-tuning fuzzy controlstrategy is presented. A PID-type fuzzy controller (FPIDC) is designed which hasintegration comparing with normal fuzzy controller. A self-tuning structure is alsointroduced against the strong nonlinearity and asymmetry of the APSS, which revises theoutput scaling factor of the FPIDC. The results of simulations show that the proposedcontrol strategy can eliminate the effects of the strong nonlinearity and asymmetry andbetter performance is achieved.Finally, an experiment platform is designed and established. The computer controlsoftware is also carried out. The experimental study of the APSS is implemented. Theresults show that it is practicable to adopt self-tuning fuzzy PID control strategy in theAPSS. The control system has improved and stable performance at any working point andexcellent dynamic response at a low pressure (under10kPa) is also achieved.The researches lay a solid foundation for working further development on the Pressuresimulation system，especially the research on extremely low pressure simulation.