NASA’s Langley Research Center has developed hardware and software to track the flight of tethered vehicles, including kite-like, airborne wind energy (AWE) generation systems. The control system consists of a pan-tilt platform and a visible-spectrum digital camera, combined with tracking control software running on a standard PC. The system controls the flight of the vehicle to keep its position on a power-producing trajectory, maximizing velocity (but within limits). This trajectory produces tension, which turns the ground-based generator, producing the energy. The NASA system enables effective operation of groundgen or flygen types of AWE systems. NASA has a working prototype and pre-beta software, and is seeking development partners to make it more robust and user-friendly by testing it in real-world systems.
Comprised of a camera, load cells, encoders, an anemometer, and software, the tracking system is based on digital photo analysis. The system tracks where the kite is 30 times every second. The controller makes an adjustment to the tether winch to keep the kite in the controlled trajectory to maximize power at high velocities without exceeding the limits of the hardware. Langley has built and generated power with a 2-kW demonstrator with two tethers (each with its own servomotor), and a pan-tilt unit to extend the field of view of the camera. NASA has flown the system many times and has collected an abundance of flight data. A video of the demo is available at http://www.youtube.com/watch?v=DCfw1B2XGQc .
The system uses low-cost components, and provides tracking and control for both groundgen and flygen systems (allowing the designer to move the control system from the kite end to the ground). The technology can potentially scale to enable groups of hundreds of kites to fly in flock formation for scalable power. It can be utilized as either a primary or backup system, and can be used in both land-based and offshore applications.