Motion Control Research Of Flight Simulator

The flight simulator is a very important device used in the hardware-in-the-loop simulation of the flight control system on the ground.And it needs avery high position/speed tracking accuracy. However,the nonlinear frictiondisturbance leads the precise mathematical model of the turntable systemcannot be established and affects the tracking performance of the turntable indifferent degrees. Especially when running at a low velocity, the nonlinearfriction disturbance makes "flat "," crawl "," dead ",the tracking error getslarger, the tracking accuracy decreases significantly. Thus,the simulationcredibility reduces seriously.It is quite necessary to design a control strategy to eliminate the influenceof friction. To solve this problem, this paper presents a compound controlstrategy based on the extended state observer. The main research contents areas follows:（1）Taking a UUT type vertical flight simulator as an example, thispaper studies on the mathematical model of the turntable system establishmentprocess with the manager analysis method,and obtains a simplified model oftwo order ideal turntable system under specific conditions. Gets the identifiedcorresponding parameters using the fitting spectrum analysis method.At thesame time,a correlative analysis about adverse effects caused by the nonlinearfriction is also taken. In order to understand the friction phenomenon moreclearly and lay the foundation for designing related friction compensation later,the classic Stribeck friction model is established.（2）The idea of extended state observer comes out from the view ofstate observer. The linear high-gain extended state observer(HLESO) and nonlinear extended state observer (NESO) which hold a high accuracy and fastconvergence of the estimation are both introduced. The nonlinear friction istreated as an external interference of system when running at a low velocity.Therefore, a compound control strategy based on the extended state observercomes out. The real-time estimation of the friction is achieved by ESO, theturntable system is transformed into linearization system by the design offriction compensation.The closed-loop control of system decides the trackingperformance of the whole system.（3）The classical control method is difficult to achieve the ideal controleffect, so the sliding mode control theory is choosed to design the closed-loopcontrol for some advantages such as robustness. To restrain the chattering ofsliding mode and solve the question that the traditional reaching law can nottake both the approaching speed and convergence time into account, a newreaching law combined index and power. Considering simple linear slidingmode control is easy to adjust. For the turntable system, the appropriatefunction of linear sliding surface is selected, and the corresponding slidingmode control law is designed. To achieve the control purpose of making thetracking error approaching to zero in finite time quickly,this paper breaks thelimit of the traditional linear sliding mode state of the system can only get agradual approach. The appropriate function of nonsingular terminal slidingmode control (NTSMC) surface is selected, and the corresponding slidingmode control law is designed for the turntable system. MATLAB simulationresults show the effectiveness of the two kinds of sliding mode control strategybased on extended state observer.（4）An introduction of host computer and slave computer is madefollowing the modular drawing, control, communication forms after taking acomprehensive analysis about the real-time operating platform of a UUT type three axis electric flight simulator. Meanwhile,the real-time operation interfaceand the concrete operation process are given. The results of the experimentshow the effectiveness of the linear sliding mode control strategy based on anew reaching law applied to the inner frame.