多軸旋翼機滯空時間與酬載能力之最佳化設計

Abstract

無人飛行載具 (Unmanned aerial vehicle)是現代極具代表性的應用科技，可應用於軍事的定點監控與民生的空拍及物流等等。不論何種任務，無人機的飛行時間與酬載能力都是相當關鍵的要素。本文針對具有垂直起降與定點懸停特性的旋翼機，提出兩種最佳化設計：其一為以鋰聚電池作電力來源進行探討，經由預先實驗而得的馬達搭配螺旋槳之推力功率關係圖、機身重量、推力單元重量、以及鋰聚電池之能量密度，便可找到最佳之電池重量或容量使得旋翼機可以操作於合適功率，並且使得無人機具有最長飛行時間或者最大酬載能力。其二為類風箏系統，由地面發電機、電源供應器或者市電插座透過電線傳輸能量至無人機，分直流與交流兩種。直流系統電壓源為24伏特定電壓源，必須選擇合適的電線線徑，使得此系統得以工作並且具有較佳的工作範圍或者較大的酬載能力。交流系統中，旋翼機搭載交流轉直流之電源供應器，由於交流電壓端以220伏特或較高電壓傳輸，傳輸時的電流下降，亦能達到與直流系統相同之能量傳遞，使得電線線徑得以大幅縮小，以利輕量化無人機系統。 本文依據內文提出的最佳化設計，首先介紹所使用的硬體設備；其次，解說原理及其數學模型；再次，呈現模擬、實際操作流程與結果，最後提出結論與展望。本次研究可對現有無人飛行載具之電池重量或容量選擇與最佳功率操作最佳化，亦可對類風箏系統針對特定飛行高度選擇合適之直流或交流電力飛行模式，完善達成最大飛行時間、最大酬載能力以及最大工作範圍之目標。

Unmanned aerial vehicles (UAV) have comprehensive applications, including military and civil ones. Now people start to think applying UAVs on serious tasks such as aerial photography, surveillance and logistics if UAVs own endurance and the capacity to lift payload. This article proposes two optimum designs. One is to determine the battery’s weight, capacity and the most efficient working power for motors. By comprehensively considering motors’ thrust-power curve, self-weight, and the specific energy of the battery, largest endurance and/or payload capacity can be achieved. Analytic, simulation, and experimental results show this optimum design method is valid. Moreover, a kite-like UAV is leashed by a taut tether, which supplies electric power from the ground generator or battery including DC and AC systems. Although working range is restricted, the flight time is extended significantly. In DC systems, a payload model of kite-like UAV is developed by measuring electrical and mechanical characteristics of the UAV’s propulsion unit. There exits an optimum electric cable selection to achieve maximum payload capacity, largest flying range, or highest flying altitude. Simulation results and experiment indicate the proper electric cable selection is crucial for kite-like UAV. In AC systems, an AC/DC power supply is carried by UAVs. With the same power transmission, the current can be decreased by using higher voltage source. Therefore, AC kite-like UAVs can use thinner and lighter electric cable. Simulation results and experiment indicate kite-like AC system UAV can reach at most 79 meters high without carrying payload for FreeX with 22 AWG cable.