Design Of Engine Speed Controller For Small Unmanned Helicopter

Small unmanned helicopters are widely used in both military and civil areas,which is regarded as an important research subject by institutes and enterprises.Technically,the performance of an unmanned helicopter is greatly influenced by the quality of its engine speed controller.The most common-used engine speed controller for Small unmanned helicopters is GY-701 from FUTABA Company,which is,however,a kind of foreign technology.In this paper,the engine speed control system of an unmanned helicopter is studied and designed,involving modeling of a two-stoke piston engine,model identification of the engine,design of the engine speed controller,and simulation experiments.The specific content are as follows:1.Modeling of a two-stoke piston engine.Comparing different domestic and abroad engine modeling methods,a mean value method is selected in this paper.2.Engine speed measuring and data filtering.The engine speed measurement hardware unit is designed based on Atmega8 L MCU,and the engine speed is computed by T-method.Then,both moving average filter and least square filter are applied on data processing.3.Engine model identification.Step signal and frequency sweep is determined as the input signal respectively.A step-signal-based identification experiment and a frequency-sweep-based identification experiment are implemented.The engine system model is then acquired by recursive least-square method.The results show that frequency-sweep-based method is more accurate on identification.4.Design of the engine speed controller.Both typical PID controller and fuzzy PID controller are designed to stabilize the engine speed,respectively.The performance of the two controllers are tested by MATLAB simulation including comparison of step response and disturbance rejection.The results show that both the response time and setting time of the fuzzy PID controller are shorter,which also performs better on disturbance rejection.Therefore,the fuzzy PID controller is determined as the engine speed controller,with real-time experiment verification.The research in this paper optimizes the flight controller of unmanned helicopters,lowers the cost of assembly,and gets rid of the reliance on abroad engine speed control technology.