Search and rescueNew micro helicopters for search and rescue missions

Within the framework of the EU project sFly, researchers at ETH Zurich have developed a new type of flying robot which can be navigated using only on-board cameras and a miniature computer. The micro helicopters does not require either GPS or remote control, thus reaching a new level of autonomy.

Research has been going on around the world further to develop and improve micro helicopters, also called Micro Aerial Vehicles (MAV). Until now, the solutions have not exactly matched the elegant flight of a bird. Currently, flying robots are large and heavy, and when used in open fields they often require GPS or a trained pilot.

The EU project sFly, launched in 2009, made it its goal to develop flying robots that go beyond these limitations. The development work has now been completed and the flying robots have successfully passed a series of demanding tests.

An ETH Zurich release reports that one innovation of the flying robots is that the devices are able to stabilize and locate their position using only the cameras and a miniature computer installed on board, without the need of a connection to the ground station. The flight movements of the helicopter are calculated in real time from the camera images. A flight control unit compares these with the required values and corrects them in case of deviations.

This technology, developed in the Autonomous Systems Laboratory at ETH Zurich, has two advantages compared with GPS-based flying robots. First, it works both in the open air and in enclosed spaces. The second is that the flying robots can navigate where GPS fails (GPS would fail, for example, owing to the density of buildings). The camera-based technology allows for a more accurate positioning of the aircraft than is possible with GPS, explains the project coordinator, Davide Scaramuzza.

Depending on the environment, GPS errors can be as great as seventy meters — too imprecise when several flying robots are in close proximity to each other in the air.

One of the three on-board cameras provides data for a flight control unit, and the other two are used for 3D modeling. Via WiFi, the on-board computer transmits the recorded images to a computer on the ground, which then creates a 3D map of the over-flown terrain. The 3D map shows obstacles for the flying robots, and it is possible to use it to calculate, for example, the best position for a complete surveillance of the area. The technology of the 3D modeling was developed by the Institute for Visual Computing at ETH Zurich.

One of the disadvantages of the conventional construction of flying robots is their weight and thirst for energy. This is why it was one of the goals of sFly to develop more efficient algorithms which require less processing power, while also increasing the computing power of the flying devices. In collaboration with Ascending Technologies, a Munich-based company that specializes in flying robots, a flying robot with six rotors was developed that weighs only 1,500 grams, including three on-board cameras and a miniature computer.

The new micro helicopters have a diameter of about fifty centimeters. They are designed to maneuver in tight or even enclosed spaces, and to detect and fly around any obstacle. Possible uses could include protection or rescue missions. They are ideal for flying over disaster areas and giving a picture of the situation from the air or locating victims. “This is a research project that above all aims to explore the technical possibilities. However, we can well imagine that the flying robots developed in the sFly project could be an important aid for rescue teams in disaster relief missions in the not too distant future,” says Roland Siegwart, head of the Laboratory for Autonomous Systems.