There are many jobs in the construction industry that fall under the “boring, dirty, and dangerous” category that are considered ripe for automation – but few can actually be taken on with today’s technology. Such a job is the crucial but repetitive task of rebar binding, the A startup called SkyMul aims to fully automate with drone fleets.
Unless you have put reinforced concrete together at some point in your life, you may not know what rebar is. The steel reinforcement that gives strength to concrete floors, walls, and other structures is held in place during the casting process by tying it to the other reinforcement where the bars cross. For a good sized building or bridge this can easily be thousands of connections – and the process is generally done manually.
Rodbusters (as rebar tying specialists are called, as I have heard) are masters of the art of looping a short piece of plastic or wire around an intersection between two pieces of rebar and then twisting and tying it tightly so that the bars are are secured in several directions. It has to be done precisely and efficiently, and it is done – but it is groundbreaking, repetitive work. While every professional has to take pride in what they do, I doubt anyone will appreciate the chronic pain they get from doing the task thousands of times in that hour. As expected, rodbusters have high injury rates and develop chronic problems.
Automation of rebar binding is difficult because it occurs in so many different circumstances. A prominent semi-robotic solution is that TyBotThis is a kind of rail portal that hangs above the surface. This makes sense for a bridge, but much less for the 20th floor of an office building.
Credit: SkyMul
Step into SkyMul, a startup that is still in its very early stages but has a compelling pitch: tying rebar through a fleet of drones. When you consider that the binding process doesn’t take too much force and that the image processing has gotten more than good enough to pinpoint the spots that need work, it sounds obvious.
CEO and co-founder Eohan George said they were evaluating a number of different robotic solutions, but that drones are the only ones that make sense. The only legged robots with the dexterity to fight their way through rebar are too expensive, and treads and wheels are too likely to move the unsecured rebar.
Credit: SkyMul
This is how the company’s SkyTy system works. First, a mapper drone flies over the construction site to mark the boundaries and then, in an automated closer overflight, creates a map of the reinforcement itself and where the ties need to go. This card is then double-checked by the Rodbuster technician running the show. According to George, rebar only takes about a minute per thousand square feet (though that adds up quickly).
Then the binding drones are released, as many as needed or desired. Everyone moves from point to point, levitating and descending until their binding tool (similar to human rodbusters) spans the reinforcement intersection. The tie is wrapped, twisted and the drone moves to the next spot. They have to change their batteries every 25 minutes, which means they generally have 70-80 ties to take off. Right now, every drone makes a draw every 20 seconds, which is in line with people who can do it faster but generally go about as fast or slower as George quoted.
It is difficult to gauge the cost savings and the value of the work SkyTy does because the value of the work varies widely. In some places, rodbuster make north of $ 80 an hour, which means automation translates into cost savings. In other markets, however, the pay is less than a third of that which, along with the risk of injury, makes rodbusters a scarce amount – so the value lies in availability and reliability. Drone-based binding seems to offer value one way or another, but that means the business model is somewhat in flux as SkyMul is figuring out what makes the most sense. Generally, contractors at one level or another would lease and eventually own their own drones, although other methods are being explored.
Credit: SkyMul
The system also offers value-added services, such as the exact map of the reinforcement generated at the beginning, which can be archived and later used for maintenance, quality assurance, comparison with plans and other purposes. Once a contractor is convinced that it is as good or better than the hand-made ones currently in use, it can save hours, turn a 3-day job into a 2-day job, or otherwise simplify logistics.
The company plans to initially offer SkyTy as an option for bridge construction. This is a simpler environment than a multi-story building for the drones. The rebar services market there is on the order of $ 30 million to $ 40 million per year, providing an easier route to more complex deployments.
SkyMul is seeking funding after spinning off Georgia Tech and going through Comcast NBC accelerator The Farm and then earning a SBIR Phase I award from the National Science Foundation (hoping for a Phase II). They have demonstrated the system but haven’t completed any pilot programs – partnerships are in the works, but the construction business isn’t nimble and a drone-based solution isn’t trivial to swap out for human rodbusters at short notice. However, once some projects are completed, the company is likely to find serious appeal with forward-thinking contractors.