多螺旋桨太阳能无人机推力分配方法研究

Exploring an Effective Method of Thrust Allocation for Solar-Powered UAV with Multiple Propellers

太阳能无人机的设计需以能量为核心,太阳能无人机多采用分布式推进系统,对推力分配进行优化可以有效提高螺旋桨效率进而提高能源利用率。在推力到桨效率的函数为凸函数的情况下,螺旋桨效率之和最大分配问题可以近似转化为拉力二范数最小分配问题,使用伪逆法解决了拉力二范数最小分配问题。将伪指令v d的误差最小作为优化目标之一考虑,形成混合优化目标,用不动点法求解了混合目标分配问题。螺旋桨的衰减滞后特性会增大伪指令误差,使用动态增益对螺旋桨动态特性进行补偿。对比数字仿真结果,不动点法相比伪逆法在降低了伪指令误差的同时,可以有效兼顾推进系统效率最高的目标;动态增益补偿可以有效削弱螺旋桨动态特性对整个推力分配系统造成的不利影响。

Designing a solar-powered unmanned aerial vehicle （UAV） should center on its energy. As the majority of solar-powered UAVs have distributive propulsion systems, the optimization of their thrust allocation may effective- ly enhance the efficiency of the propeller and energy utilization. When the function from thrust to propeller efficien- cy is a convex one, the maximum allocation of the sum of propeller efficiency can be approximately converted into the two-norm minimum allocation of thrust, which can be achieved with the pseudo-inverse method. Taking the minimization of the error of the pseudo-instruction as one of optimization objectives, we obtain the mixed optimiza- tion objective. Then we use the fixed point method to achieve the mixed optimization objective. As the attenuation and hysteresis of the propeller may increase the error of the pseudo-instruction, we use the dynamic gain to compen- sate for the dynamic characteristics of the propeller. Finally we simulate the thrust allocation of the solar-powered UAV and the compensation for the propeller＇ s dynamic characteristics. The simulation results, given in Tables 1 through 4 and Figs. 4,5,7 and 8 ,and their comparison show preliminarily that： （1）compared with the pseudo-in- verse method, the fixed point method can not only reduce the error of pseudo-instruction but also effectively achieve maximum energy efficiency of the propulsion system ;（2） the dynamic gain compensation can effectively reduce the adverse influence of the propeller＇s dynamic characteristics on the thrust allocation.