TU Berlin Department of Computer Science		Institute for Technical Computer Science Real Time Systems & Robotics

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Flight

Flying a path for Marvin is always flying from one three-dimensional waypoint (i-1) to another (i). These (lists of) waypoints are normally sent by an external entity like the Mission Control. Marvin has two different flight modes. One is straight line and the other curved. When flying straight line mode, the system takes the shortest path from waypoint i-1 to i usually nose ahead. If i is reached, it stops, turns toward i+1 and accelerates. Marvin is flying the way with a given (maximal) cruise speed. When flying curved mode, the helicopter keeps the cruise speed until it reaches the last way-point and does not stop at every intermediate way-point. To achieve that, the control switches from waypoint i to i+1 as soon as the helicopter is so close to i that it would need to slow down to stop at point i. The result is a smooth transition between waypoints. It is possible but rarely used to fix the direction of Marvin's nose while flying. The mission flight speed is typically 2 to 5 m/s, but successful flights have been performed with a velocity of 14 m/s. The above shows a simulated flight. Red lines are straight and blue lines are curved mode flight path.   The above shows a real curved flight [mm] Insight The flight range of the helicopter in its current state is about 300 m due to two issues. Firstly, as long as a human pilot should be able to recover the helicopter in case of an emergency it has to be somewhere in the middle of the area because the visual range is about 150 m. Secondly, DECT and WLAN are officially limited to 300 m but this is solely a monetary issue which could be solved easily. The maximum flying height is an even more difficult question. A maximal ascending speed of 2 m/s is feasible, but flying beyond a height of 50 m is risky since this is the maximum height that a human pilot is able to fly. Disregarding the safety factor, the reachable height is 300 m as well due to the radio components. Safety is an issue. It may seem a pretty small helicopter but if one looks at the technical data and think about it one will see, that there are rotating blades with 1350 rpm, having a diameter of 1.84 m and weight 0.25 kg each. Therefore, the tip of the blade has a speed of more than 450 km/h and each blade is pulling with a force of about 2800 N outwards. Some flights can be seen in the video section.

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