Measuring wind turbines remotely using laser

 The rotor and mast of a wind turbine can oscillate even in normal operation. The analysis of these oscillations plays an important role when the equipment is being developed and maintained. Up to now, this analysis has only been possible at discrete points located directly on equipment. Researchers at the Fraunhofer Institute in Germany use modern information technology to remotely measure the oscillatory pattern over the entire structure of the facility from several hundred meters away.
Laser tracks movement of the rotor blades automaticallyKaufmann and his colleagues have taken on this problem and developed a system with which the oscillation analysis can be completely carried out from a distance of several hundred meters. The system consists of a laser that is directed at the installation and able to measure the oscillations at all points on the surface. To accomplish this, the laser automatically tracks the motion of the moving parts like the rotor blades. The centerpiece of the system responsible for this is an IT-based tracking system combining a camera and a laser. These are mounted on a head that can pan and tilt to follow the rotor blades. The camera records images of the installation and forwards these along to software that processes the images and builds a model of the rotary motion from the data. With the help of this information, the pan and tilt head is positioned so that the laser automatically follows the rotor blades. The camera simultaneously collects data about the exact position of the roughly two-to-three centimetre laser spot on the rotor blade in order to stabilise it on the revolving surface.
This way, as many points on the equipment as are needed can be scanned during operation – even from a great distance. “Considerably more comprehensive analyses can be carried out very quickly than are possible using fixed sensors. The measurement interval is variable: the slower the oscillations, the longer the laser takes measurements,” says Kaufmann.