SkyMul’s drones secure rebar on the fly to speed up construction

There are many jobs in the construction industry that fall under the “dull, dirty, and dangerous” category said to be ripe for automation — but only a few can actually be taken on with today’s technology. One such job is the crucial but repetitive task of rebar tying, which a startup called SkyMul is aiming to completely automate using fleets of drones.

Unless you’ve put together reinforced concrete at some point in your life, you may not know what rebar tying is. The steel rebar that provides strength to concrete floors, walls, and other structures is held in place during the pouring process by tying it to the other rebar where the rods cross. For a good-size building or bridge this can easily be thousands of ties — and the process is generally done manually.

Rodbusters (as rebar tying specialists are called, or so I’m told) are masters of the art of looping a short length of plastic or wire around an intersection between two pieces of rebar, then twisting and tying it tightly so that the rods are secured in multiple directions. It must be done precisely and efficiently, and so it is — but it’s backbreaking, repetitive work. Though any professional must feel pride in what they do, I doubt anyone cherishes the chronic pain they get from doing that task thousands of times in an hour. As you might expect, rodbusters have high injury rates and develop chronic issues.

Automation of rebar tying is tricky because it happens in so many different circumstances. A prominent semi-robotic solution is the TyBot, which is a sort of rail-mounted gantry that suspends itself over the surface — but while this makes sense for a bridge, it makes far less for the 20th floor of an office building.

Animated image of a drone floating over rebar and tying it together at intersections.

Image Credits: SkyMul

Enter SkyMul, a startup still in the very early stages but with a compelling pitch: rebar tying done by a fleet of drones. When you consider that the tying process doesn’t involve too much force, and that computer vision has gotten more than good enough to locate the spots that need work… it starts sounding kind of obvious.

CEO and co-founder Eohan George said that they evaluated a number of different robotic solutions but that drones are the only ones that make sense. The only legged robots with the dexterity to pick their way through the rebar are too expensive, and treads and wheels are too likely to move the unsecured rebar.

Diagram showing how SkyMul's drones map an area of rebar then divide it up for tying.

Image Credits: SkyMul

Here’s how the company’s SkyTy system works. First, a mapper drone flies over the site to mark the boundaries and then, in an automated closer flyover, to build a map of the rebar itself and where the ties will need to go. This map is then double-checked by the rodbuster technician running the show, which George said only takes about a minute per thousand square feet of rebar (though that adds up quickly).

Then the tying drones are released, as many as needed or wanted. Each one moves from spot to spot, hovering and descending until its tying tool (much like those used by human rodbusters) spans the rebar intersection; the tie is wrapped, twisted, and the drone is off to the next spot. They need their batteries swapped every 25 minutes, which means they generally have time to put down 70-80 ties; right now each drone does one tie every 20 seconds, which is in line with humans, who can do it faster but generally go at about that speed or slower, according to numbers George cited.

It’s difficult to estimate the cost savings and value of the work SkyTy does, because the value of the labor varies widely. In some places rodbusters are earning north of $80/hour, meaning the draw of automation is in cost savings. But in other markets the pay is less than a third of that, which compounded with the injury risk makes rodbusters a scarce quantity — so the value is in availability and reliability. Drone-based tying seems to offer value one way or the other, but that means the business model is somewhat in flux as SkyMul figures out what makes the most sense. Generally contractors at one level or another would lease and eventually own their own drones, though other methods are being looked into.

Animated image of a computer-generated grid overlaid on images of rebar.

Image Credits: SkyMul

The system offers value-add services as well, for instance the precise map of the rebar generated at the beginning, which can be archived and used later for maintenance, quality assurance, comparison with plans, and other purposes. Once a contractor is convinced it’s as good or better than the manually-produced ones currently used, this could save hours, turning a 3-day job into a 2-day job or otherwise simplifying logistics.

The plan at the company is to first offer SkyTy as an option for bridge construction, which is a simpler environment than a multi-story building for the drones. The market there is on the order of $30-40 million per year for rebar tying services, providing an easier path to the more complex deployments.

SkyMul is looking for funding, having spun out of Georgia Tech and going through Comcast-NBC accelerator The Farm and then being granted a National Science Foundation SBIR Phase I award (with hopes for a Phase II). They have demonstrated the system but have yet to enter into any pilot programs — there are partnerships in the works but the construction business isn’t a nimble one and a drone-based solution isn’t trivial to swap in for human rodbusters on short notice. But once a few projects are under its belt the company seems likely to find serious traction among forward-thinking contractors.

Corporate sustainability initiatives may open doors for carbon offset startups

Commitments to carbon neutrality keep coming from all corners of the business world — over the past few weeks, companies ranging from the fast-casual restaurant chain Sweetgreen to the security-focused networking IT company Palo Alto Networks to the online craft retailer Etsy committed to net-zero carbon emission plans.

As the companies look for ways to reduce their energy consumption, they’re turning to carbon offset programs as a stopgap measure until the energy grid decarbonizes, they implement technologies to reduce their energy consumption, or both.

This push toward corporate sustainability is creating all kinds of strange bedfellows and startup opportunities, with major corporate offset programs and the establishment of new startups focused on offsets creating channels for sustainable technologies to get to market.

The latest example of a company leveraging a sustainability angle to tie a corporate partner even closer to their business is the agreement between Delta and Deloitte, which involves the accounting and consulting firm paying Delta for renewable jet fuel to offset the emissions of its corporate travel.

To be clear, a better policy for Deloitte would be to cut back on non-essential travel significantly and focus on doing as much remote work as possible to reduce the need for flights. But in some cases business travel is unavoidable, and most folks want to get back to a pre-pandemic normal, which — at least in the U.S. and other countries — will include significantly ramping up air travel for a percentage of the population.

As the BBC noted, air travel accounts for roughly 5 percent of the emissions that contribute to global climate change, but only a small percentage of the world actually uses air transport. According to one analysis from the International Council on Clean Transport, just 3 percent of the world’s population flies regularly. And if everyone in the world did fly, aircraft emissions would top the CO2 emissions of the entire U.S.

Which brings us back to Deloitte and Delta and startups.

Delta’s deal to buy sustainable aviation fuel that would offset a portion of the carbon emissions associated with Deloitte’s business travel is one small step toward greening the airline industry, but the question is whether it’s a significant first step or just an attempt to greenwash the unsustainable travel habits of a consulting industry that prides itself on such perks.

Geothermal startups get another boost from Chevron as the oil giant backs a geothermal project developer

The U.S.-based oil major Chevron is doubling down on its investment in geothermal power by investing in a Swedish developer of low-temperature geothermal and heat power projects called Baseload Capital.

Oil companies are under pressure to find new lines of business as the world prepares for a massive shift to renewable energy resources to power all aspects of industry in the face of mounting climate-related disasters caused by greenhouse gas emissions warming the temperature on the planet.

Joining Chevron in the investment was the ubiquitous billionaire-backed clean energy investment firm Breakthrough Energy Ventures and a Swedish investment group called Gullspang Invest AB.

The investment into Baseload follows closely on the heels of another commitment that Chevron made to the geothermal technology developer Eavor and a recent Breakthrough Energy Ventures investment in the Google-affiliated company, Dandelion Energy (a spinout from Google’s parent company’s moonshot technology development business unit, called X).

Dandelion and Eavor are just two examples of a groundswell of startups working to leverage the knowledge from the oil and gas industry to tap geothermal resources for applications ranging from baseload energy to home heating and cooling.

They’re joined by businesses like Fervo EnergyGreenFire Energy and Sage Geosystems, who’re all leveraging heat to generate power.

As Chevron noted in its press release, heat power is an affordable form of renewable energy that can be harnessed from either geothermal resources or waste heat.

The investments in Baseload and Eavor are financed by CTV’s Core Venture fund, which identifies companies with technology that can add efficiencies to Chevron’s core business in operational enhancement, digitalization and lower-carbon operations, the company said in a statement.

Together the two businesses are planning pilot projects to test technology and could look to current Baseload operations in Japan, Taiwan, Iceland or the United States to develop projects.

Financial terms of the deal were undisclosed. 

“In August, we announced that we were looking for a new strategic investor to help us accelerate deployment in our key markets,” said Baseload’s Chief Executive Officer Alexander Helling. “We couldn’t have asked for a better one. Chevron complements our group of owners and adds expertise in drilling, engineering, exploration and more. These assets are expected to accelerate our ability to deploy heat power and strengthen our way of working.”


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Hackers release a new jailbreak tool for almost every iPhone

An iPhone hacking team has released a new jailbreak tool for almost every iPhone, including the most recent models, by using the same vulnerability that Apple last month said was under active attack by hackers.

The Unc0ver team released its latest jailbreak this weekend, and says it works on iOS 11 (iPhone 5s and later) to iOS 14.3, which Apple released in December.

Jailbreaking is a cat-and-mouse game between security researchers who want greater control and customizations over their phones, and Apple, which says it locks down iPhones for security. Hackers build jailbreak tools by finding and exploiting vulnerabilities that can lift some of the restrictions that Apple puts in place, like installing apps outside of its app store, which most Android users are already used to.

In a tweet, the jailbreak group said it used its “own exploit” for CVE-2021-1782, a kernel vulnerability that Apple said was one of three flaws that “may have been actively exploited” by hackers. By targeting the kernel, the hackers are able to get deep hooks into the underlying operating system.

Apple fixed the vulnerability in iOS 14.4, released last month, which also prevents the jailbreak from working on later versions. It was a rare admission that the iPhone was under active attack by hackers, but the company declined to say who the hackers were and who they were targeting. Apple also granted anonymity to the researcher who submitted the bug.

The group’s last jailbreak, which supported iPhones running iOS 11 to iOS 13.5, was fixed in a matter of days last year. Apple works quickly to understand and fix the vulnerabilities found by jailbreak groups, since these same vulnerabilities can be exploited maliciously.

Security experts generally advise iPhone users against jailbreaking because it makes the device more vulnerable to attacks. And while keeping your phone up to date may introduce security fixes that remove the jailbreak, it’s one of the best ways of keeping your device secure.


Early Stage is the premiere ‘how-to’ event for startup entrepreneurs and investors. You’ll hear first-hand how some of the most successful founders and VCs build their businesses, raise money and manage their portfolios. We’ll cover every aspect of company-building: Fundraising, recruiting, sales, legal, PR, marketing and brand building. Each session also has audience participation built-in – there’s ample time included in each for audience questions and discussion.


Tonal triples its physical stores with Nordstrom partnership

Tonal, maker of the smart home fitness trainer, announced it is more than tripling the number of physical locations it sells devices in through a new partnership with Nordstrom.

Starting this month, Tonal will have 50-square-foot stations in the women’s activewear departments of at least 40 Nordstrom locations across the U.S., bringing the total number of Tonal physical locations to 60 by the end of 2021. Shoppers will be able to walk in or book appointments to try Tonal devices and purchase them through employees on-hand.

“As we looked to expand our retail footprint and strategy, we looked to the retail landscape, and we really feel like Nordstrom says ‘best-in-class’ — the department store is well-suited to succeed in a COVID and post-COVID world,” explained Christopher Stadler, Tonal’s CMO.

Tonal, which manufactures a wall-mounted device with a digital weight system that emulates various traditional gym stations, already operates 16 locations across the country with devices shoppers can try and work out to, with plans to open four additional showrooms later this year. But the partnership with Nordstrom, which expects overall sales growth of 25% in 2021, marks a first-of-its-kind for at-home fitness makers. Peloton, for instance, operates a larger network of dedicated showrooms in the U.S., Canada, Germany and the UK, but it has yet to partner with an outside retailer to display and demo its bikes and treadmills.

An example of Tonal’s placement at a Nordstrom in Walnut Creek. Photo via Tonal.

Tonal’s physical expansion arrives amid a boom in demand for at-home equipment during the pandemic. According to Stadler, sales of Tonal equipment surged 800% from December 2019 to December 2020, causing 10-12 week wait times for deliveries. Those delays are somewhat comparable to Peloton, which has also faced significant delivery wait times in recent months and currently reports 6-10 week delays — an issue Peloton CEO John Foley acknowledged and apologized for in a note to users.

Tonal, for its part, is working to address shipment delays. According to Stadler, the startup has significantly ramped up production of devices, increased employee headcount, and in some cases, now air-ships equipment from Taiwan to the U.S. to meet demand.

“We have seen extraordinary demand for Tonal, and we’re working aggressively around the clock to produce, deliver and install Tonals faster and faster,” says Stadler. “We’ve absolutely ramped up production, and all facets of the organization are rallying to deliver our customer orders as quickly as we can.”


Early Stage is the premiere ‘how-to’ event for startup entrepreneurs and investors. You’ll hear first-hand how some of the most successful founders and VCs build their businesses, raise money and manage their portfolios. We’ll cover every aspect of company-building: Fundraising, recruiting, sales, legal, PR, marketing and brand building. Each session also has audience participation built-in – there’s ample time included in each for audience questions and discussion.