Boston Dynamics Unveils Stretch Gen 2 for Reliable, Consistent Performance

Boston Dynamics Inc. this week unveiled Stretch Gen 2, the second generation of its autonomous mobile trailer unloading robot. The new Stretch features an updated modular design that enables "plug and play" part swaps, and the company built it to maximize uptime and streamline maintenance. The first generation accumulated over 100,000 operating hours and handled tens of millions of boxes.

Brian Donnelly, vice president and general manager of logistics robotics at Boston Dynamics, told The Robot Report that the company worked on the new version for about two and a half years. He said the first generation was focused on getting a product to market quickly but was not easy to manufacture due to many components.

With Stretch Gen 2, Donnelly said the focus shifted to simplification, hardening the robot, and improving reliability and performance. The goal was to make the robot better in every way, he added.

The robot can unload up to 1,000 cases per hour, a rate that depends heavily on case weight and how neat or disorderly cases are stacked. It features a multipick capability, a battery that lasts two shifts, and a fast charger that reaches 90% charge in about 75 minutes. Onboard lighting and a pre-trained vision system allow it to work in dark trailers and detect most packages without programming.

Boston Dynamics reduced internal cabling by 81%, cutting about half a mile of wiring. Donnelly noted that cabling adds weight, cost, and failure points, especially when a robot is in constant motion, creating strain on cables with every movement. Hyundai helped source a cable harness through its automotive supply chain.

The robot uses heavy-duty automotive-grade connectors that withstand vibration from rapid, high-torque box handling and driving over uneven floors. Donnelly said the automotive industry deals with real-world challenges like shock and vibration, and using latching connectors gives the company confidence that connectors will stay together in the field. It also has continuous rotation joints that move beyond 360° without hard stops, improving trajectory planning and productivity. The emergency stop is now lower and recessed, and exterior panels use new materials to reduce accidental safety stoppages or breakage.

The upgraded gripper features new valve systems and more precise sensing. Each suction cup has a valve, enabling multiple boxes to be picked in a single arm motion, which significantly increases throughput, Donnelly explained. The gripper also configures boxes on the conveyor and uses less power by only activating suction when good contact is detected.

Serviceability has been improved with standardized high-strength fasteners, cutting tool changes and repair time. A full swerve drive swap now takes one hour instead of a day. The robot does not require dynamic cables and complex harnesses, and onboard diagnostics and maintenance tools allow customer teams to handle routine service, reducing reliance on outside support.

Donnelly said the company did not have as much serviceability experience when it made the first-generation robot. Since then, it has deployed robots, serviced them in the field, and hired experienced people whose input helped make the robot more manufacturable and serviceable.

The redesigned onboard computing platform supports regular software updates for case detection, motion planning, pick strategies, and world modeling across the fleet. Donnelly said the most recent update delivered a 24% increase in unload rate, and software is released monthly on average.

Stretch Gen 2 is already running at multiple customer sites, deployed within two weeks. Donnelly said customers are pleased and find the robot simple to operate, requiring minimal training. A person can drive the robot into a container, step out of the safety work cell, and press a Play button, and then the robot does the rest. Many operators previously did repetitive heavy lifting, which Donnelly described as one of the worst jobs in the warehouse due to temperature extremes and physical strain.

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