From Spot to Stretch: The Evolution of Boston Dynamics' Uncanny Robots

As the company unveils another robotic marvel, we look back on the technology that preceded it.
Eric James Beyer
A robotic dog and crane armEric James Beyer/

Depending on who you ask, Boston Dynamics is either a pioneering robotics company helping to usher in a technological revolution or a harbinger of the coming robot apocalypse. Over the last decade, the manufacturer has built robots that can run, jump, and even dance better than at least some of their human counterparts.

It’s easy to take the progress as a given—which is what tech companies do, after all—but such advances really are quite remarkable. In March 2012, the Twitter account Wonders of Science posted a side-by-side comparison video of just what ten years of progress at the company actually looks like:

The rate of this progress is unlikely to slow down anytime soon as the company looks to diversify its influence in the coming years. In a press release from December 2020, Boston Dynamics confirmed its acquisition by Hyundai Motor Group, explaining how the pairing would help spearhead the company’s expansion into the logistics automation market. Reinforcing this claim was an indication that they would release a “mobile robot for warehouses in 2021.” 

In March of this year, they followed through on that announcement by unveiling the prototype for Stretch, a Wall-E-esque, mobile crane arm designed to automate case handling in warehouse settings without the need for large, costly, and inflexible infrastructure. The robot uses a visual artificial intelligence system known as “Pick,” which helps it adapt to the ever-changing arrangement of boxes it handles.

Stretch may be Boston Dynamics’ most boring robot to date. It can’t open doors, do backflips, or even move all that fast, but the machine is likely to appeal to the global network of hundreds of thousands of warehouses looking to automate and expedite as much of their workload as possible. 

"A lot of that same design thinking has gone into Stretch."

Stretch isn’t the perfect machine. It can only handle boxes of up to 50 lbs (23 kg) in weight, move those boxes at a rate comparable to that of a human worker, and features a battery life of about eight hours (of course, it can also operate plugged-in).

Some are skeptical about how efficiently the machine can operate given the sheer scale of variability of warehouse environments, however, and the robot has a year or so of testing via pilot customers to prove itself before Boston Dynamics releases it commercially in 2022.

In a recent interview with The Verge, Boston Dynamics’ VP of business development Michael Perry explained how Stretch is built on the foundation of much of the company’s robot technology that precedes it, especially that of its bipedal, virally-popular parkour phenom Atlas:

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“Atlas picking up a box isn’t just about extending the arms and moving them, it’s about coordinating the hips, legs, and torso [...] A lot of that same design thinking has gone into Stretch.” 

As the company continues to advance its robotics to the curiosity of both industry leaders and the general public, let’s take a look back at some of the technology that predates Stretch and where Boston Dynamics might take that technology in the future.

BigDog - 2004

Funded by the Defense Advanced Research Projects Agency, better known as DARPA, BigDog was the first legged robot the company put out in the field. It was a bulky quadruped built to help carry heavy gear for soldiers and handle rough terrain using gyroscopes, joint positioning sensors, stereovision, and LIDAR (light detection and ranging) to stay upright. 

The robot was surprisingly adept at keeping its legs under itself, despite appearing endearingly awkward in early videos posted by Boston Dynamics’ YouTube channel which showed it fumbling up and down hills and being kicked by its testers. 

Capable of carrying 400 lbs (181 kg) and able to interpret voice commands, the US military repeatedly tested the robot to determine how well it could be used in service.

Various iterations of BigDog were developed, including the 2010 LS3 that was better able to handle rugged terrain and carry heavier payloads, but the military ended up dropping the robotic mule in 2015. Speaking to, Kyle Olson, a spokesperson for the US Marine Corps Warfighting Laboratory, stated the machine was simply too loud to be used practically.

Wildcat - 2011  

Wildcat was something of an experiment in speed for Boston Dynamics, which is slightly ironic, given that this robot weighed 330 lbs (150 kg). Like BigDog, it was a quadruped, but its short legs were bent at a sharp angle. Featuring a two-stroke gas engine, it was the loudest of the company’s robots, and achieved speeds of just under 20 mph (32 km/h) in tests. 

Spot (Classic, Mini) - 2015  

The original Spot, which has since redubbed Spot Classic, was the indoor/outdoor quadruped that marked a turning point in Boston Dynamics’ robot development. It featured a pipe chassis and exposed internal components. Weighing in at around 160 lbs (72.5 kg), it was smaller, faster, and more agile than the BigDog models that came before it. This size reduction came from the use of an electric instead of a gas engine to power its hydraulics system. 

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The company released an even more compact version of the machine in Spot Mini in 2016, which is now the flagship design for the Spot model. Boston Dynamics had replaced Spot’s hydraulics system with an all-electric one for the robot’s locomotion, paring down its heft to a much more manageable 55 lbs (25 kg). The robotic dog now features two payload ports and can carry up to 31 lbs (14 kg) in weight. 

Boston Dynamics describes Spot Classic as the machine that “laid the groundwork for the robust dynamic robot control seen on Spot today.” Spot was also the first robot the company decided to release commercially, making it available to consumers in June 2020 for a cool $74,500.

Atlas - 2013

Atlas is Boston Dynamics’ humanoid robot marvel, the one you’ve likely seen on YouTube bounding up boxes and front-rolling across laboratory floors like some kind of mechanized secret agent in training. 

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First released in 2013, Atlas stood at 6’2” (1.8 m), and weighed 330 lbs (150 kg). The company originally made the robot for the DARPA Robotics Challenge, a competition meant to accelerate the development of robotics technology for use in aiding response efforts to both natural and human-made disasters. 

The robot has undergone significant changes since that debut, thanks in part to the company’s 2013 acquisition by Google and an exploration of the capabilities of 3D printing technologies. 

"Atlas' purpose is really to drive innovation inside our group."

In a 2018 interview with The Robot Report, Aaron Saunders, BD’s VP of engineering expressed his enthusiasm for how such printing is changing the way they build their machines.

“We can make very organic structures and minimize pressure drops—get rid of a lot of excess components,” he explained. “It’s kind of exciting, the things that can be done in printing manifolds.”

The current model stands at 4’11” (1.5 m) and weighs 176 lbs (80 kg) and features hydraulic actuation of an impressive 28 joints. According to Boston Dynamics’ website, Atlas uses complex algorithms to calculate the speed and coordination of its movement. 

Atlas isn’t currently commercially available, but it was never meant to be. 

This robot’s [purpose] is really to drive innovation inside our group,” Saunders explained, “to push us to understand how to marry controls on complex machines.”

Handle and Stretch - 2017

All of those innovative explorations are finding their way into the robots we’re now seeing come out of Boston Dynamics. Stretch has a good deal of its ancestry in Atlas, but more directly so in a robot called Handle, which the company has called “a research venture into wheeled robots.” 

Handle deftly balanced on two wheels and, just like Stretch, was capable of unloading trucks and even building pallets. The prototype was updated in 2019 but never commercially released. As we’ve seen, the company is banking on releasing Stretch next year with an eye to cornering the warehouse market—but that isn’t the only market they’re looking to establish a foothold in. 

How AI drives the dog 

In January 2020, Vinsa, a visual AI solutions firm, began selling Spot robots that were running a special AI vision software it had developed. Because one of Spot’s core features is the ability to navigate rough terrain, the robot has frequently been used in the inspection of industrial areas that pose a potential threat to human health, like oil rigs and construction sites. 

While the robot dog is capable of using its sensors to capture visual data from these sites, Vinsa’s AI enhances that data, combining thermal imaging, gauge reading, and leak detection scans to highlight abnormalities in things like production lines and assesses the overall safety of a particular site. 

The folks at Boston Dynamics were impressed by what Vinsa was doing with Spot and, in May 2020, officially began supporting the integration of the software with its robot dog and helping Vinsa expand its network of pilot customers. 

These AI upgrades have been a big help to their users—thanks to Vinsa’s intelligence models, the robot becomes more than a reconnaissance-gathering tool and actively aids its operators in making choices that could save them time, money, and lives. 

As Vinsa’s co-founder and chief AI officer Daniel Bruce said in an interview with The Robot Report last year, “Vinsa enables near-term [return on investment] by taking visual data captured by Spot and turning it into action — automating laborious tasks, detecting anomalies or threats sooner, and optimizing inspection hours from humans. Vinsa helps the implementation of robotics and AI to pay for itself.”

Collaborations that combine advanced AI systems with state-of-the-art robotics are yet another indication of how such technology will change the face of just about every industry there is in the near future. The prospects are certainly alluring. 

If Boston Dynamics can tap into warehouse automation as promisingly as it has made industrial inroads with Spot, the company will have a highly-profitable future ahead of itself, and we will have more entertaining YouTube videos to watch. Indeed, after spending years tinkering, refining, and innovating in the garage, it looks like such a feat wouldn’t be all that much of a stretch.  

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