Wind turbines can get big – really big. For example, the 6 megawatt Enercon E-126 turbine has a rotor diameter of 126 meters and sits atop a tower 138 meters high.
Constructed of special fibreglass and reinforced plastics, rotor blades of large turbines have to withstand a great deal of pressure and long term general exposure to the elements, so regular checks must be made to ensure optimal operation and negate safety risks. The size and general structure of a commercial wind turbine can make inspection and maintenance quite a tedious and dangerous task.
Researchers at the Fraunhofer Institute for Factory Operation and Automation IFF have recently developed RIWEA, a robot that checks the rotor blades of wind turbines. Equipped with a number of advanced sensor systems, RIWEA can inspect rotor blades closely, finding minute cracks in the surface and potential weaknesses in bonds and joints.
The inspection system consists consists of an infrared radiator that conducts heat to the surface of the rotor blades. A high-resolution thermal camera then records the temperature pattern, identifying potential flaws in the material. An ultrasonic system and a high resolution camera are also on board, allowing for the detection of damage that may be missed by the human eye.
The RIWEA can can autonomously pull itself up ropes, has sixteen degrees of movement and a specially developed carrier system ensures that the inspection robot is guided securely and precisely along every centimetre of the surface of a rotor blade; making a job usually carried out directly by maintenance workers much more efficient and much less risky.