DragonPlate™ CFRP Components Improve Reliability of Climbing Robots

ITHACA, N.Y. — “Anyone can make a robot that moves along the ground or through the water, which is why we leave the easy stuff to others,” laughs Sam Maggio, president, International Climbing Machines (ICM, here). “What’s really tough is making robots that can climb up surfaces through the air, so that’s what we focus our expertise on. We design and build robots that can scale virtually any vertical, rounded, or inverted surface to perform dangerous tasks that otherwise could put humans in grave danger.”

For the last 15 years, ICM has applied its expertise to produce innovative, patent-protected wall-climbing robots. When it was time to cut the weight of early robot designs, Maggio — who already was familiar with the many benefits of using advanced composites — turned to a local company, DragonPlate™ (Elbridge, N.Y., U.S.) to provide design and engineering services and produce high-performance carbon-fiber-reinforced plastic (CFRP) components that nearly halved robot weight. A side benefit was that the high-precision carbon composite structures also improved reliability and reproducibility (R&R) versus earlier aluminum designs.

ICM’s easily deployable climbing machines are small, nimble, and durable robots operated via remote control by a single operator on the ground. Thanks to a patented rolling seal, which Maggio developed, the devices seemingly defy gravity as they scale walls and ceilings and move across obstacles like bolt heads, weld seams, and plates on uneven or highly contoured surfaces without losing their grip. The standard climber weighs 45 pounds/20 kilograms without tools and is roughly 24 inches long by 21 inches wide/61 by 53 centimeters and 9 inches/23 centimeters tall (to the top of the platform on which tools are mounted). Still, the robots can carry heavy payloads (up to 50 pounds/23 kilograms), including interchangeable attachments such as cameras, gauges, ultrasonic test equipment, ground-penetrating radar, paint/coating/adhesive applicators, lasers, brushes, cutters, abraders, or blast media. A secondary vacuum provides for full waste capture.

The robots are ideally suited to traverse surfaces that would be difficult or dangerous for humans to cross, such as bridges and highway overpasses, tanks and towers, ships and planes, wind turbines, dams, and plants/refineries. As a consequence, they keep humans from having to work in cramped spaces or at dangerous heights or to be exposed to toxins like heavy metals, or radiological, chemical, biological, or explosive agents. They can conduct the non-destructive evaluation (NDE) and testing (NDT), such as checking stress cracks in dams and bridges after an earthquake, or evaluating coating thicknesses on water tanks, or making minor repairs to wind-turbine blades without having to remove the blades from their towers. Install brushes, abraders, or blast media and the robots are ready to remove lead paint or surface corrosion. Next, mount a pressure-fed roller or spray applicator and the robots can repaint/recoat the surfaces they just cleaned. Maggio believes that one day the robots will be an important tool in emergency-response situations to help people escape burning buildings. At a cost range of $60,000 to $75,000 USD before tools are installed, they also are quite affordable compared with alternatives that are much heavier and cost in excess of $1-million USD.

To maintain versatility, it was critical to keep robot weight with tools installed under 60 pounds/26 kilograms to ensure vacuum pressure was strong enough to maintain contact between the robot and vertical or overhead walls. Another early issue was that the aluminum chassis ICM first used was actually warping under the pressure of the applied vacuum used to maintain a connection to vertical and overhead surfaces. Maggio and his team turned to engineers at Dragonplate to redesign the chassis. “The Dragonplate team was so successful at taking weight out of the chassis versus the aluminum system we had been using that I asked them to redesign the superstructure, which holds tools mounted to the top of the robot and, eventually, the transition bar and the forward hook, which connects the robot to its tether should power be interrupted,” recalls Maggio. “I always felt they were rooting for us.”

“We’ve really enjoyed working on this innovative project as it’s evolved,” recalls J.B. Allred, president, Allred & Assoc., Inc., which owns DragonPlate. “Sam was very focused and had a lot of experience and understanding about what he wanted to accomplish with his robots. And we’re pretty good at working with people to help them apply carbon fiber composites to their application. Our two teams worked closely during the design and development of each component to ensure the structural components were as light as possible but could support the high loads. We’ve continued to work closely to find ways to refine the design to improve performance and reduce cost.”

Dragonplate technicians utilized a variety of carbon composite materials and processes to produce various components. All parts are produced in carbon fiber-reinforced epoxy composite. Some components are formed using unidirectional, plain and twill weave prepregs (all standard modulus, 3K, and 12K fiber tows), which are vacuum-bag molded or highly consolidated via a heated hydraulic press to make extremely strong and stiff plates. The team also uses resin-transfer molding (RTM) of preforms and fabrications with carbon fiber braid. Owing to the unique shapes of some of the components, they are subsequently machined and bonded with Dragonplate’s stock shapes. Among the most intricate assemblies, the “cannons” that form part of the superstructure feature complex cores that keep the parts extremely stiff but lightweight.

One of the benefits of switching from aluminum to carbon composite for key components of the robot’s structure is that dimensions became more repeatable and reproducible (had higher R&R) and the robots performed more consistently. “When we used an aluminum-framed chassis, it was still early in our initial development program and we wanted the flexibility to be able to adjust the design quickly at that stage,” explains Maggio. “However, once past the prototype stage, converting all the key structural components to advanced composites really upped our quality and consistency, and saved us the time and trouble of having to sort those issues out ourselves.”

“We’re very disciplined in how we make things,” adds Allred. “If you’re molding something, your tooling controls geometry, and if you’re CNCing it [using computer-numerically controlled (CNC) cutters], then your cutter paths control geometry.”