50 m-range distance and position measurement method by using two searchlights for autonomous flight device
Abstract
In the present study, 50 m-range distance and position measurement method for autonomous flight device such as four-rotor drone by using two searchlights was proposed, and the precise distance/position measurement performance was evaluated in an outdoor situation. To realize over 10 m long-distance flight of the drone under unstable GPS signal situations such as under the bridge or inside tunnels for periodic inspections, the correct self-position measurement is important for the stable control. This study is to propose a simple method of over 50 m range autonomous four-rotor helicopter movement control using high power 300W two searchlights as InfraRed sources on the ground and the direction of the searchlights sets to the investigation target position such as bridge side. High power light sources of the two searchlights are enabled to measure the correct drone position via an attached drone's camera with an InfraRed filter, and it realizes 1.5 m standard deviation position estimation error when 50 m distance in an outdoor daylight situation. In addition, the limitation of the position detectable condition also measured and analyzed in other experiments. Our proposed method would be effective in the situation that there is no skilled the drone control operator and the flight by visual confirmation of man are hard conditions, and useful to develop the position measurement system with low cost.
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Introduction
In this paper, 50 m-range distance and position measurement method for autonomous flight device such as four-rotor drone by using two searchlights was proposed, and the precise distance/position measurement performance was evaluated. Such as under the bridge, inside tunnels and buildings for the periodic inspection at unstable GPS signal situations, to realize over 10 m long-distance flight of the drone, since it is unable to confirm the real-time drone posture by the naked eye, easy and correct self-position measurement method is necessary for the stable inspection work [1,2] (Fig.1). Even if a human controls the drone, the flight by the naked eye of man is difficult in the over 10 m long distance flight [3-11], and another supporting mechanism of the position measurement and the control method would be necessary [12-25]. This study aims to propose a simple method of 50 m range distance and position measurement method for autonomous four-rotor helicopter using high power 100V AC two searchlights as InfraRed sources on the ground and evaluate the practical measurement ability of the distance/position in case of 50 m distance outdoor situation.
Conclusion
In this paper, 50 m-range distance and position measurement method for autonomous flight device such as four-rotor drone by using two searchlights was proposed, and the precise distance/position measurement performance was evaluated in an outdoor situation. This study is to propose a simple method of 50 m range distance / position measurement using high power 300 W two searchlights as InfraRed sources on the ground. In experiment 1, the IR88 (wavelength is 880 nm) InfraRed filter extracts only the light of the searchlights and it is not affected by ambient light such as light reflected on the white snow. Experiment 2 measured the maximum distance/position detectable area of the drone (camera position), and it was affected by the 𝑑 of the distance between two searchlights (the 𝑙 and 𝑑 take a linear approximation relationship 𝑑 = 0.017𝑙 at least 50 m). The result of experiment 3 shows the distance/position displacement by the camera angle changes from 0 to 16 deg, and the displacement was extended by increasing of the camera angle 𝜃, and there was 2.8 m displacement when 50 m distance and 16 deg condition. In the last experiment 4, the positional measurement accuracy in the area of 3 m × 50 m was confirmed when 𝑑=1 m condition. There were about 3% displacement errors in each axis 𝑠 and 𝑙, and this evaluation results would be useful to develop the position measurement system with low cost.