Control Of A Laboratory 3-DOF Helicopter: Explicit Model Predictive Approach

Helicopter is widely used in military and civilian areas for its superior flight characteristics such as spot hovering, vertical take-off and landing. So helicopter research is very important.Since helicopter flight control system is a typical multi-input multi-output system with strong channel-coupling and nonlinear characteristics, the research will prove challenging.In order to cope with the problems encountered in current controller design, this paper presents an explicit model predictive control( EMPC) of a 3-Degree-of-Freedom(3-DOF)helicopter and validate the effectiveness of EMPC by numerical simulation and Hardware In the Loop(HIL) experiment. Since researches before mainly limited to numerical simulation, this paper will comparatively enrich the application of EMPC.The contents of this paper that will be discussed are listed as follows.1. On the basis of detailed introduction of 3-DOF helicopter control system and its main parts, a state-space presentation of the system is established according to the characteristics of each degree of freedom motion.2. In order to cope with the problems encountered in current flight controller design that state constraint, input and output constraint and delay cannot be addressed effectively, this paper presents a MPC control for attitude regulation and tracking of a 3-Degree-of-Freedom(3-DOF)helicopter. However, traditional MPC is not suitable to control large-scale systems or systems of fast dynamic changes due to the burden of online optimization. Then EMPC is introduced. By introducing Multi-parametric Quadratic Programming, EMPC moves the online-computation offline and turn online-computation into a simple table-search process. How EMPC works is detailed described. Moreover, region division process of offline-computation is expressed with examples as well as online-computation.3. Attitude controller design and numerical simulation. Controller for attitude regulation and tracking are designed and numerical simulation is conducted. During the controller design,the way to determine proper control parameters and their effect on offline-computation and performance are discussed. Tracking is simulated by tracking different kind of signals, like square and sine waves.4. HIL experiment. To further validate the theory, HIL experiment is conducted, on the basis of numerical simulation. Attitude regulation and tracking are presented. In tracking,reference signals are square wave and sine wave. To analysis the performance of EMPC, both the results of EMPC regulations and PID regulations are presented for comparison. To test the immunity to interference of 3-DOF helicopter, two jobs are done, firstly, after regulating to equilibrium, manual interference and ADS disturbance system is provided respectively to test the performance of the controller under abrupt and persistent interference; Secondly, in tracking sine wave, ADS is also added.5. Finally, the research work of this paper is concluded and the future goals and interested research direction are described.