Research On Key Technology Of Motion Cueing For Flight Simulator

With the rapid development of national economy and aeronautic industry, the flight simulator has become the indispensable test and simulation equipment in the pilot training and aircraft development, because of its safety, economy, reliability and high fidelity. Especially, under the background of independent development large civil transport, the need for flight simulator is more urgent. As an typical instance of man-in-the-loop real time simulation technique, the motion system supply the motion cues for the pilot in flight simulator. And the motion cues are the important channel to estimate the aircraft state, so the motion cueing fidelity directly affect the fidelity of the whole flight simulator. Therefore, the purpose of this research is to supply the high fidelity motion cueing environment for flight simulator.The washout algorithm is the key technique of motion cueing for flight simulator, using six degree of freedom parallel mechanism. The role of the washout algorithm is to provide the motion cues, using the limited working space of the parallel mechanism. And the motion cues is produced by the aircraft in the infinite space. Washout algorithm has been a research focus in the motion cueing, and its form is variety, but the adaptive washout algorithm is widely used recently. The adaptive washout algorithm can turn the its adaptive parameter according to motion state of motion base, to provide high fidelity motion cues when the motion base in the neutral position, and to avoid exceeding its working space when the motion base near the limits. But the six degree of freedom parallel mechanism is nonlinear system, the motion range of each degree of freedom is related to the motion base pose. So the washout algorithm, designed in the motion base neutral position, can still exceed the motion limits, when the motion base in large posture. In addition, the adaptive high pass filter in the adaptive washout algorithm will become unstable with the large input signal amplitude.To solve this problem, the composition and principle of the adaptive washout algorithm was studied, and the kinematics of the Stewart platform was also analyzed. Based on Stewart platform kinematics, a single degree of freedom motion range calculation method, which can work in the real time environment, was presented. Using this method, the algorithm outputs can be corrected to reduce the possibility of exceeding its limits causing by the motion range changed. So the parameters of the adaptive washout algorithm can be turned more"open"to improve the fidelity of motion cueing.The stability of the adaptive high pass filter was researched using the Hurwitz criterion. According this research, the relationship between the filter parameters and input amplitude was gotten to keep the adaptive high pass filter stable. Using this result, the filter parameters can be specified according to the aircraft worst maneuver, so the adaptive washout algorithm can keep stable during the flight simulator working.In the other hand, to solve the vibration coupling problem caused by the Stewart platform heavy load and high center of gravity, when the Stewart platform simulated the high frequency sinusoidal vibration specific effect, the dynamics of Stewart platform was studied, and the multi-rigid body dynamics model was build. According to this research, a vibration control method was proposed based on the Stewart platform dynamics. This method can achieve the high frequency vibration precision control in the Stewart platform position control loop. And the Stewart platform can simulate the flight simulator specific effect, when the motion base is in the washout motion.At last, using the flight simulator key technique experiment and research platform and six degree of freedom parallel mechanism, the improved adaptive washout algorithm were verified. The results show that, the improved adaptive washout algorithm can improve the fidelity, when the motion base has enough motion space. And it also can avoid the possibility of exceeding limit, when the motion base has small motion space.In a word, the improved adaptive washout algorithm and the dynamics based specific effect simulated method can achieve the purpose of improving the motion cueing fidelity.