Research And Design Of Power Planning For Small Unmanned Helicopter Flight Control

The unmanned helicopter equipped with a small-sized engine has been widely used in military and civil fields by virtue of its dynamic stability and long endurance.Traditionally,the controller keeps the engine rotating at a constant speed during the whole flight controlling process of the helicopter.Obviously,it is not an optimized plan as this very speed is set to ensure that the engine is able to work under extreme circumstances,which causes a waste of power.However,during the regular flight of the helicopter with this constant speed plan,the safety margin of the engine is too sufficient,while the engine does not perform the best on saving energy.This paper is focus on the minimization of the total power requirement of an unmanned helicopter under stable flight condition and calculation of the optimum main rotor speed under minimum power requirement,in order to keep the engine rotating at the best speed corresponding to the certain flight conditions.Then the engine can perform well to save power.Additionally,by this approach,the adaptability of the helicopter can be improved as well as the endurance.The main work is as follows:(1)To establish the nonlinear model of a small unmanned helicopter.The nonlinear dynamic model of the helicopter is established and the relevant parameters are obtained to build a simulation platform for optimization.(2)To establish the calculation model of power requirement.Based on the momentum theory and blade element theory of the rotor,the power requirement calculation of the main rotor is analyzed thoroughly during both vertical flight and forward flight.The objective function for optimization is established according to the calculation model of the power requirement.(3)Optimization design and simulation experiments.In order to minimize the power requirement,the theory of matching optimized main rotor speed with the manipulated variable properly is studied,and the optimization and simulation model is put forward.Based on that,hovering condition and different forward flight conditions of the unmanned helicopter are simulated and the corresponding optimized rotor speeds are obtained.The simulation results show that it is feasible to reduce the total power requirement of the helicopter under a certain stable flight condition.(4)Engine power planning experiment.The optimized-speed plan is implemented in real-time flight experiment in which the error tracking performances of the speed and flight envelope show a great success in terms of saving energy in practical.All in all,the engine speed can be considerably reduced when the helicopter is flying stably under a good condition so that the goal of saving fuel and increasing the endurance can be achieved.