Research And Design Of The Engine Control System For Small Scale UAV

Small scale UAV, which is short for Unmanned Aerial Vehicle, has been a new focus because of its particular flight speciality. However, most of the available small scale UAVs choose high capacity battery as their power, which restricts UAV’s flight range. In order to expand UAV’s flight range, a kind of two-stroke gasoline engine with small displacement is the best selection. But gasoline engine’s speed is not so steady as electric motor, which could deteriorate UAV’s flying stability. A speed control system that is independent from the whole flight control system has to be designed for the gasoline engine.Currently, there is insufficient research finding on this kind of engine and its speed control system. Thus, research on gasoline engine speed control system is of great practical significance for the UAV system used in my laboratory. Based on the requirements of this speed control system, the whole project could be divided into five parts, gasoline engine mechanism modeling, construction of experimental mechanical system and electronic system, engine model identification, engine speed controller design, analysis of control effect, respectively. Firstly, the model structure of engine is obtained by using a MVEM(Mean Value Engine Model). Secondly, a mechanical engine experimental platform is designed and built autonomously based on the condition available in the laboratory. Then an electronic system including hardware system and software system is designed. Also, some modification is applied on the current flight control system to meet the new speed control system’s demand. Thirdly, the engine speed data, measured by calculating time gap between two contiguous speed pulses which is called T method, is dealt with by the median window filtering method. The engine model is identified by a kind of method involved with step response, M sequence(Maximal Length Sequence) response and RLS(Recursive Least Square) method. Fourthly, on the basis of identification result, PID controller and a kind of Sliding-Mode PID controller are designed and tested. Last, to verify the control effect, the design achievement is integrated with the flight control system and some related experiments are conducted. In conclusion, the research achievement of this project makes up for the deficiency in current flight control system, as well as lays the foundation for researching on advanced control method of small scale UAV’s engine system.