The Wiimote camera has proven to provide accurate tracking of infrared blobs and the infrared filter avoids most disturbances caused by external light sources, except sunlight. The pixel position information can easily be interpreted as an unambigious pattern on a target. A microcontroller is capable of estimating the position to the target and controlling a miniature flying robot in hovering flight with our approach. The field-of-view of the Wiimote camera is big enough for adjustment moves and tracking even in small distances. The deviation from the desired position, which we obtain with our control algorithm, is small enough for quasi stationary flight for a longer time in an indoor environment. High level autonomy tasks could start from this position. The distance to the target is limited, but by enlarging the dimension of the pattern and increasing the IR light emission by using multiple IR LEDs per point or stronger LEDs, the operating distance can be increased. However, an accurate roll and pitch estimate, provided by the IMU of the aircraft is essential. A small angular error leads to inadmissible position approximation. A second Wiimote camera, or fusion with other sensors would lead to better positioning at a larger distance. By accelerating the IMU request, or integrating the tracking control loop in the internal program of the UAV, the control fequency could be increased considerably. A higher control frequency would advance the control accurancy and a customised control design would eliminate most of the remaining oscillations. However, the current frequency of 20 Hz is sufficient for robust hovering control. A pattern where not all LEDs are lying in one layer, but M is raised in positive z direction, allows for better analysis. Assuming the aircraft operates in limited space above the landing place, such a 3D-pattern allows for estimating the x and y position in addition. This could lead to a flight control, independent from the IMU, if the achieved accuracy is sufficient.
Low-cost visual tracking of a landing place and hovering flight control with a microcontroller
Kostengünstige visuelle Verfolgung eines Landeplatzes und Schwebeflugsteuerung mit einem Mikroregler
2010
15 Seiten, 9 Bilder, 2 Tabellen, 19 Quellen
Aufsatz (Konferenz)
Englisch
Springer Verlag | 2013
|Test flight method for simulating hovering environment of vertical take-off and landing aircraft
Europäisches Patentamt | 2024
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