3-DOF Helicopter Multi-model Controller Design Based On LQR And H∞

In this article, the 3-DOF helicopter is researched as the main laboratory equipment. First, we make a detailed analysis and modeling on 3-DOF helicopter from its mechanism and features, and get its modeling motion equations by the knowledge of physics.From the analysis of the model, the system is with the problems of nonlinear and state interference. First, we get the linear state space through linearity of the system. And then, we use the theory of Linear Quadratic Regulator (LQR) to get the optimal state feedback controller from the linear state space. The simulation and experiment results show that it can't realize the optimal effect on whole elevation work space due to the system approximation.According to problems of LQR state feedback control on nonlinear model application, we divide the whole elevation axis into multi-parts and design controller parameter respectively to make a performance improvement. We make the elevation desired value as the input of fuzzy logic controller, and get the output as the weighting coefficient of the multi-controller. It can realize the multi-model control and smooth switching between each state. After LQR robustness analysis, we design three multi-model parts and get each parameter. The simulation and experiment results show that we can get great improvement on the control quality after multi-model design based fuzzy logic control on nonlinear model, and we can realize the smooth switching between each state.Finally, due to the system modeling disturbance caused by ADS (Active Disturbance System), we add a H∞part to the multi-model controller based on LQR. We can also add the weighting coefficient of H∞part by detecting the stable state error using the fuzzy logic controller, so we can farthest overcome the interference on the system. The simulation and experiment results show that we can get great improvement on the control quality.