Operators and inspectors have traditionally gained access to massive wind towers and their huge blades by using cranes, bucket trucks, rappelling teams, or by inspecting blades with high-power telescopes. Two different remote-controlled climbing robots have been developed to make wind tower maintenance easier, cheaper, and safer.
Helical Robotics recently demonstrated its latest model, the magnetic HR 1000-LL (Light Lift) climbing robot, at the American Wind Energy Assn. 2012 Conference and Exposition in Atlanta. (See the robot in action below.) This model hauls 50 pounds to 100 pounds of video cameras, nondestructive testing equipment, robotic arms, and lifts all the way up a wind tower's shaft and can be controlled by a single operator.
GE Global Research has been conducting tests with International Climbing Machines' tower-climbing robots, which use vacuum force to adhere to wind towers. (Source: International Climbing Machines)
The Helical Robotics' design is built to work on ferrous surfaces using the company's magnetic adhesion system. The robot's wheels are driven by electric motors that propel it up, down, and around the tower. Different models can carry payloads ranging from lightweight cameras to heavy industrial equipment.
The latest model, HR 1000-LL, self-aligns to a work surface, and is adjustable to between 0.030 inch and 0.25 inch from that surface. It measures 57 inch x 22 inch x 20 inch high, and weighs a total of 90 pounds to 145 pounds, depending on configuration. The robot gives wind tower operators and inspectors a real-time view of tower maintenance tasks from its onboard cameras. HD video can also be transmitted live to offsite personnel in a ground station using a custom-designed wireless bridge network.
Meanwhile, GE Global Research has been conducting tests with tower-climbing robots made by International Climbing Machines (ICM) on GE's wind turbines at a Texas wind farm. ICM's climbers are held to a surface with vacuum force. The robot platform consists of a vacuum chamber surrounded with a rolling locomotive seal, which lets them climb over uneven surfaces, surface contours, and surface obstacles.
The ICM robot is made of carbon fiber and advanced composites. Each weighs about 30 pounds and has a pull-off strength of more than 225 pounds. It measures 24 inch x 24 inch x 8 inch high, and travels at 2.5 inch to 3 inch per second. The robots have been used for inspecting and cleaning surfaces, spraying on coatings, and testing coatings for their integrity, as well as nondestructive testing and evaluation inspection. They can carry wireless HD video equipment to give operators on the ground a real-time view of the wind tower's blades from about 30 feet away. (Watch videos showing demonstrations of this robot here and here.)
For a better view of the blades, GE is developing a microwave scanner that the climbing robotic vehicle could carry. Microwave inspection would also let operators analyze the blade material's composition and integrity for early indications of possible breakdowns in the structure.
HelicalRobots, thanks for diving in and answering readers' questions. Beth's window washing question brings up one I had: what is the theoretical height limit, meaning, what is the power source and how far can they travel on it (or what's the half-height limit, since they have to get down again)?
All of the current systems are battery powered and have a 4 hour continous run time. The climb rate is up to 753 inches per minute, or 3,780 ft per hour on our fastest robot. There are many other variables such as control range, but essentially our limitation is the height of the structure. We could convert the system to be tethered as well limiting us to that length, but currently there is no need.
I've seen a couple shows demonstating how maintainance is done on these towers and the ability to use a robot would definitely be a way to get more done. No need to call people down due to the wind if a robot is doing the work.
I also wanted to say thanks for joining this discussions. It's great to get answers from the experts. So the model show uses magneting technology to climb the fins while you have other models that can climb non-magnetic surfaces?
Like Greg, I was also curious and a bit skeptical about the holding technologies, both vacuum and magnetic, under various conditions. What about rain and sleet and snow?, although the vacuum seal does sound pretty strong. But like Jack, I wonder about the advance of non-ferrous metals.
I have seen a magnetic surface inspection "thing", and it does appear to hold on very well. The vacuum adhered robot would be much more flexible as to what it could climb on, but I can visualize a real problem if the power fails unexpectedly. That is a challenge that would need to be dealt with somehow.
Robots could be designed for a large range of climbing operations, possibly including window washing on high buildings. So there is an existing area where robots could indeed provide a real benefit.
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