Boston Dynamics unveils Stretch Gen 2, a tougher truck-unloading robot

Stretch is a box-moving robot for warehouses. It is a wheeled base with a long arm on top and a gripper that holds boxes with suction cups.

Its main job is unloading. When a truck or shipping container shows up with boxes stacked on the floor, Stretch drives inside, picks them up one by one and puts them on a conveyor belt that carries them into the building.

The company calls this one of the hardest jobs in a warehouse. VP Brian Donnelly, who runs logistics robotics at the company, said it plainly: "Fundamentally, unloading trailers is one of the worst jobs in the warehouse." A container that sat in a yard all summer can be brutally hot. In winter it can be freezing.

The first Stretch was built to reach customers fast. Donnelly said the team wanted to get a product into the market as quickly as possible, and that it "was not the easiest to manufacture."

Since then the robots have piled up experience. Boston Dynamics says Stretch has logged more than 100,000 operating hours and handled tens of millions of boxes. The team studied that data to find what takes robots offline, then designed Gen 2 around those problems.

Donnelly said the work took about two and a half years. The goal was "simplification, hardening the robot, and really driving improved reliability and performance."

Here are the main hardware changes, as the company describes them:

• 81% less cabling: about half a mile of internal wire is gone. Cables in a robot that moves constantly get bent again and again, and that wear causes faults.
• Automotive-grade connectors: these are the plugs that join parts together. They are built to stay latched through shaking and bumpy floors. Donnelly said Hyundai, which owns Boston Dynamics, helped source a wiring harness through its car supply chain.
• Joints that never hit a stop: the new joints can keep rotating past 360 degrees. Old joints had hard stops that put stress on the metal. This also lets the robot pick a smoother path.
• A safer emergency stop: the button now sits lower and is recessed, and new panel materials mean a falling box is far less likely to set off a false stop or crack a panel.

In real life Think of a laptop charger cable that frays near the plug because you bend it every day. Stretch has fewer of those weak spots, so fewer things can wear out.

The new gripper can pick up several boxes in one arm movement, which pushes the peak rate to 1,000 cases per hour.

A "case" is one box. The company says the real speed depends on weight and on how neatly the boxes are stacked, so 1,000 is a best case, not a promise for every truck. The first Stretch typically handled 600 to 800 cases per hour.

Why does carrying two boxes help so much? Donnelly explained that most of a pick cycle is arm movement. If the arm travels the same distance but carries more, you get more boxes per trip.

Every suction cup in the gripper is sensed and controlled on its own. A cup only opens its valve to pull air when it touches a box. That saves power, because the vacuum pump is not pulling air through cups that hold nothing. It also lets the robot set the boxes down one at a time on the belt.

Yes, and this may matter most to the people who buy it. When a warehouse robot is down, boxes pile up at the dock.

Boston Dynamics removed the flexing cables and complex wiring harnesses. It uses standard, high-strength fasteners, so a technician needs fewer tool changes. A full swerve drive swap now takes about one hour. Before, it could take a full day. A swerve drive is the module that both spins the wheel and steers it, which lets the base turn in tight spaces.

New built-in diagnostics also help a customer's own maintenance team handle routine repairs. That means less waiting for an outside service visit.

Stretch Gen 2 runs on a redesigned onboard computer. The company says regular software updates improve how it spots boxes, plans its movements, picks and models its surroundings. These updates reach a whole fleet with no hardware changes.

Donnelly said the latest update raised the unload rate across the fleet of robots already in the field by 24%. New software comes out roughly every month.

The vision system is pre-trained, so it recognizes most packages from day one without anyone programming it. Onboard lights let it work in a dark trailer.

The company says Gen 2 is already running at several customer sites and can be set up in about two weeks at existing locations.

Stretch has a track record. DHL Supply Chain announced a $15 million investment in January 2022, the first commercial purchase of Stretch. DHL later said it plans to deploy more than 1,000 additional Stretch robots by 2030. Retailers such as Gap and H&M have also used it.

The operating experience is simple, Donnelly said. A person drives the robot into a container, steps out of the safety work area and presses a big Play button. The robot does the rest. Workers who once lifted boxes all day now run the robots.

The launch comes weeks after Boston Dynamics named Rohit Prasad, a former Amazon AI executive, as its CEO. We covered that in our story on his appointment.

Boston Dynamics sells three robots: Spot, a four-legged inspection robot; Atlas, a humanoid in early production; and Stretch. Stretch is the one that earns a steady living in busy warehouses, so a more reliable version matters to the business.

The company also says Stretch is the market leader with more deployments than any competing logistics product. Other companies make unloading robots too, so that is the company's own claim.

• Faster deliveries, maybe: trucks that unload faster can free up dock space and help packages move sooner. Do not expect to notice it tomorrow.
• Safer work: hot, heavy trailer unloading is hard on the body. Robots take over the most punishing part.
• Jobs change: people who used to lift boxes are now the ones running and watching the robots, according to the company.
• Reliability is the product: the biggest upgrades here are fewer faults and faster repairs, not new tricks.