Send In The Rebar Tying Drones: SkyTy Concept Will Have Initial Flight Next Year

Marcia Doyle Headshot
Updated May 18, 2021
SkyMul SkyTy on rebar mat

The backbreaking work of rebar tying is attracting a variety of technology solutions, including the SkyTy P3 rebar-tying drone robot.

As with Tybot, which we covered a few weeks ago, the SkyTy concept (then known by its parent company’s name SkyMul) first gained U.S. contractor notice at the 2020 World of Concrete.

The SkyTy – which is still in prototype stage – uses drones to both map and then tie rebar intersections. It employs a ground station, a nimble SkyTy mapper drone and several “worker” tying drones – how many depends on the size of the project and desired production rates.

The mapper drone is designed to be agile while the beefier tying drone carries the payload of the tying tool and wire spool.

“They are really two platforms that are optimized for two different things.” says Eohan George, SkyMul CEO. “The mapper drone has a lot of optics that are not needed on the tying drone, which is optimized for hopping from between positions. The mapper drone can also fly for a lot longer.”

SkyTy gains cost and productivity scale on larger concrete projects, George says. “It would make sense to bring in our system on a 20,000-square-foot bridge deck job,” he says. For a slab-on-grade projects, which require fewer ties, SkyTy could be used on 30,000-square-foot-and-above projects. “We can probably reduce costs by almost half in many cases and in some instances, a lot more than that,” he says.

Compared with manual tying, SkyMul says using the SkyTy system can lead to an 84% reduction in labor, 2.4-times faster production rates and cost 32% less.

In talking with contractors, George says his team has discovered that not all contractors have analyzed their work procedures enough to understand how much time is spent on a specific process such as tying. “In this early stage, we really like to work with contractors who understand that in depth so they know exactly how to bring in our system into their workflow.”

George emphasizes that SkyTy is not designed to take away jobs. In fact, he says the ironworkers union recognizes it could help maintain production schedules, deal with worker shortages and reduce worker exposure to hazardous situations.

SkyTy in actionSkyTy inforgraphic

Here’s how the concept works: A crew member – or ironworker rodbuster on union jobs – first marks the parameter of the rebar area that needs to be tied. This process takes about an hour, George says. The mapper drone automatically flies over the area, building a map of the rebar, identifying grid spacing and blank intersections.

The crew member then uses a semi-automated interface to verify grid spacing and placement accuracy of the placed rebar, SkyMul says, allowing verification of “hundreds of square feet of rebar in a matter of a few minutes.”

Using the coordinates provided by the mapping drone, multiple tying drones can be deployed to do the actual tying, working in coordination and keeping out of each other’s way.

The SkyTy tying drone uses a gantry system to position the tying end directly over rebar intersections. Using the gantry system, the hopping time between positions is significantly reduced, which in turn reduces the overall time the drones are tying. “You can tie close to four intersections before the drone has to reposition itself,” George says.

Since the tying drones are controlled by what the mapping drone has mapped out, the crew member doesn’t actually fly the drone but rather handles logistics, such as swapping out batteries or changing the wire.

George says neither the mapping nor the tying drones are off-the-shelf. Both the physical drone and the software driving them are proprietary to SkyMul.

Although they are capable of working in sync, the number of tying drones required on even a large job is fairly small, George says.

These multiple drones will not be working side by side, but rather working around each other to accomplish the defined ties. “Even if they are working the same area, they are doing it at two opposite sides to reduce the chances that they’re close to each other,” George says. The drones typically stay 2 to 3 feet from each other.

Right now, each tying drone needs to have its battery swapped out every 25 minutes, tying about 70 to 80 ties on each charge and tying one rebar intersection about every 20 seconds. SkyMul is also working on a more robust battery solution for the drones.

What’s next

SkyTy will come out in phases as SkyMul works on demonstration projects with contractors.

“Our focus is to operate up to five teams for up to two years to really hone the system,” George says. “We want to be really conservative in the time it takes to get to market and we want to spend as much time working as a service to contractors.”

SkyMul has participated in the National Science Foundation’s Innovation-Corps program, which is designed to help researchers “reduce the time to translate an idea to the marketplace,” according NSI, which has also given the company a $200,000 grant.

Because of this, George says he sees the company taking on pilot services in the third quarter of 2022. “In Q4 of this year we hope to be able to do a pilot release in an actual construction environment,” he says.

SkyMul is now working with a large West Coast-based contractor that has a crew of around 150 rodbusters to explore a demonstration project. George says he’s also gotten interest from contractors building bridge decks and large slab-on-grade projects.

SkyMul has produced this video to explain the SkyTy process: