Developing and testing autonomous aircraft
The ultimate test for UAVs: Autonomous flight between unknown buildings.
December 13, 2010: Unmanned aerial vehicles (UAVs) are ideal for performing risky or monotonous tasks. For maximum autonomy, they need "sensory organs" to perceive their environment, plus intelligent mission control software. The German Aerospace Center (DLR) is developing such UAVs, using a dSPACE system for virtual test flights in the laboratory.
Artificial Sensory Organs
Modern UAVs can fly along preplanned waypoints, and some of them can also take off and land automatically. However, not one of them is able or even permitted to operate in general airspace, because they currently have no way of "seeing" their environment. To do so, UAVs need imaging sensors that capture their environment. These could be optic cameras, radar systems, laser scanners, and so on. To be used in flight control, the measurement data from the sensors has to be processed with optimum speed, ideally in real time. The "onboard intelligence", a computer inside the aircraft, then bases its decisions on this data as it plans the flight path or even decides to abort the mission in an emergency.
Virtual Test Flights with a dSPACE System
To check that the UAV flight control computer functions correctly, the DLR uses a dSPACE system for real-time simulation of the UAV's sensors (acceleration and rotational speed sensors, sonar, magnetometer, and so on), environmental conditions, flight mechanics and actuator dynamics. Additional conditions such as wind, sensor noise, sensor failure, etc., can easily be configured in the dSPACE ControlDesk® experiment software. The flight control computer uses this simulation to generate flight commands that it sends to the dSPACE system, which in turn uses the commands to compute the corresponding sensor data. This procedure enables the flight control computer to fly the mission in the laboratory as if it were on a real test flight.
Autonomous Flight over Unknown Terrain
Next the test aircraft have to pass the acid test of real flight missions. Thanks to the laboratory simulations, most of the system behavior is already known, so all that remains to be done is to find the appropriate parameters and investigate a few situations that could not be simulated. As a result of this work, the ARTIS system (ARTIS = Autonomous Rotorcraft Testbed for Intelligent Systems) is one of only a few automatic helicopters in the world that can move across unknown terrain, create a map of their environment completely independently, and operate within that environment collision-free.