摘要
近年来,无人机在军事、科学和民用领域应用广泛,引起了人们越来越多的兴趣。但由于它缺乏充分的驱动特性,限制了它的移动性和轨迹跟踪能力。本文介绍了一种过动四轴飞行器的设计和控制,它允许旋转器围绕其臂轴独立倾斜。附加倾摆机构通过获得充分的力矩和力矢量来克服上述的机动性限制。倾斜特性使控制输入增加到8个(4个螺旋桨转速加4个转子倾斜角),使四轴飞行器处于完全控制状态。基于Newton-Euler方法,推导出了转子倾斜四轴飞行器的广泛数学模型,并给出了反馈线性化方法。采用线性化方法对模型进行线性化,设计合成一种混合灵敏度H∞最优控制器,以达到所需的性能和稳定性。对控制系统进行了仿真,以保证控制器和四轴飞行器设计的有效性。测试了该控制器的抑制干扰、抑制传感器噪声和处理模型不确定等方面的性能,并对其复杂轨迹进行了试验,结果表明过动四轴飞行器优于传统的四轴飞行器。
In recent years,unmanned aerial vehicles(UAVs)have acquired an increasing interest due to their wide range of applications in military,scientific,and civilian fields.One of the quadcopter limitations is its lack of full actuation property which limits its mobility and trajectory tracking capabilities.In this work,an overactuated quadcopter design and control,which allows independent tilting of the rotors around their arm axis,is presented.Quadcopter with this added tilting mechanism makes it possible to overcome the aforementioned mobility limitation by achieving full authority on torque and force vectoring.The tilting property increases the control inputs to 8(the 4 propeller rotation speed plus the 4 rotor tilting angles)which gives a full control on the quadcopter states.Extensive mathematical model for the tilt rotor quadcopter is derived based on the Newton-Euler method.Furthermore,the feedback linearization method is used to linearize the model and a mixed sensitivity H∞optimal controller is then designed and synthesized to achieve the required performance and stability.The controlled system is simulated to assure the validity of the proposed controller and the quadcopter design.The controller is tested for its effectiveness in rejecting disturbances,attenuating sensor noise,and coping with the model uncertainties.Moreover,a complicated trajectory is examined in which the tilt rotor quadcopter has been successfully followed.The test results show the supremacy of the overactuated quadcopter over the traditional one.
