German group to test adaptive landing system

 - November 30, 2010, 6:56 AM

Researchers at the German aerospace research institute (DLR) plan to flight-test a system next year intended to aid landing in confined areas. The system relies on sensor fusion and adapts to each pilot’s typical approach strategy. It should help improve the safety record for rescue operations at unprepared sites in poor visibility, research engineer Thorsten Strohmaier said during a presentation at the European Rotorcraft Forum.

According to German statistics, 70 percent of all requests for rescue helicopters come in bad weather conditions. Some 14 percent of accidents and incidents, in turn, can be attributed to bad weather. To combat poor visibility, the DLR system uses a TV camera, an infrared camera, a laser radar and a 3.5-GHz radar. The system fuses information from air data and GPS and integrates known obstacles and noise-restrictive areas.

The algorithm takes pilot preferences into account. “Every pilot has his preferences–over or around an obstacle, low or high descent rate,” Strohmaier said. Some 80 pilots–flying for air rescue organizations and police forces in Germany–have been interviewed and the algorithm, which reflects a human cognitive process, incorporates their input.

In addition, the system can learn from each pilot’s behavior. “The system records the flight parameters of the approach paths flown by the pilot and the data of the conditions and surroundings such as wind, temperature, terrain and so on,” Strohmaier explained. The system then analyzes the pattern of the approach and draws conclusions about the pilot’s preferences.

Once the system computes an approach path, it is displayed on a head-down or helmet-mounted screen. The pilot can accept or decline it. If he chooses to decline, the system offers another approach profile.

The computed profiles can be modified manually. If the pilot is unhappy with the approach, he can change his specifications and the system plans a new approach in real time.

Once the pilot accepts the approach path the system creates, the crew can pass control to the autopilot. Included in the human-machine interface is an active sidestick (see AIN, January, page 59). If the pilot does not apply any force, the system moves the sidestick so the helicopter stays on the defined path. If the pilot applies some force, the helicopter deviates from the defined flight path. “The ­sidestick operates like a flight director leading the pilot to the defined path,” Strohmaier explained.

The flight tests will take place on a Eurocopter EC135. At the core of the trials will be real-time approach replanning. In the event that a moving or pop-up obstacle appears, the system will plan a local path that leads the helicopter just around this obstacle. The rest of the approach will remain unchanged–if safety and flight dynamics allow it.