A Four-Legged Construction Robot That Climbs Stairs
All3 unveiled the second-generation Mantis, a four-legged construction robot that carries 100 kg, climbs stairs and drives structural screws on its own.
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All3
A Four-Legged Construction Robot That Climbs Stairs
All3 describes itself as a robotics and technology company, and its homepage promises "custom housing delivered at industrial speed." The company splits the work into three stages. An AI-powered platform produces the design, robotic factories running at 90% automation make the components, and a construction robot, All3 Mantis, assembles them on site, which the company calls "the first autonomous robot designed for complex construction environments." On October 7, 2026, All3 unveiled the second generation of that robot. The site credits the approach with 10% less cost, 50% less time and 25% less CO₂, without giving a baseline.
Why Four Legs
Napo Montano, All3's Head of Mobile Robotics, explains the shape in an October 8, 2026 article. Construction sites change by the hour as materials arrive and structures rise, and the robot's own work alters the ground it must cross next. He calls such sites "pre-human," unfinished spaces unlike the homes and offices humanoid robots suit. Driving structural screws also pushes force back through the machine. In his words, "Every newton you push into a building comes straight back into the robot." A heavy body keeps the tool steady, and a four-legged robot keeps that mass low.
What the Second Generation Carries and Climbs
The robot's platform weighs 135 kg without its arm, and All3 says this makes it the heaviest electric-drive quadruped documented climbing stairs. It has four legs with 13 joints and can carry up to 100 kg while walking. A narrow 750 mm stance lets it pass a standard 900 mm doorway, and it climbs staircases up to 35° on onboard sensing alone. The six-axis arm reaches about 1.8 m and holds a screw tool or a vacuum gripper, swapped through a single connector. The whole robot fits on a Europallet. Two hot-swappable battery packs keep it running.
Fastening and Control
In repeated pilot runs, Mantis found, aligned to and drove screws into 8 of 8 holes on a building component, with tool-tip closure to 0.5 mm. All3 describes this as a demonstration outcome and not a reliability statistic. It is the first of 68 construction operations the platform is designed for, and the examples include placing columns and laying underfloor heating. A deterministic control loop running 1,000 times per second handles force, damping and emergency stops. Machine learning is used only where it measurably improves walking, planning and perception, and it is kept apart from the motors.
What Comes Next
All3 names early 2027 as the next milestone: deployment on its first live construction project. A funded twelve-month fleet programme will develop robots that cooperate, swap batteries on their own and check finished work against the building model. A telescopic arm designed to reach 4 m is in development. All3 says Mantis is built to a safety standard ahead of the EU Machinery Regulation, which applies from January 20, 2027, and that its safety assessment is in progress. Montano says of the site trial: "That is where it will be judged."
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