AI Evolved Lego-Style Robots That Thrive Outdoors — Even When Severed For most robots, the leap from simulation to the real world is a fraught transition.
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AI Evolved Lego-Style Robots That Thrive Outdoors — Even When Severed
For most robots, the leap from simulation to the real world is a fraught transition. Not so for a new breed of modular machines designed by artificial intelligence at Northwestern University.
Researchers in Sam Kriegman's Center for Robotics and Biosystems have created robots made from snap-together spherical modules — each containing a circuit board, battery, and motor — that are evolved entirely inside a computer simulation and then assembled and deployed without any retraining. The work, published March 6, 2026 in PNAS (DOI: e2519129123), marks the first time robots designed via evolutionary AI set foot outdoors and immediately performed.
"We compressed billions of years of evolution into seconds," Kriegman said, according to LiveScience. The approach works by having an AI algorithm propose millions of robot body plans, test them in simulation, and select the most capable. The winning designs are then built from off-the-shelf components and deployed directly into the real world — gravel paths, grassy fields, sand, mud, and uneven brick surfaces — and keep functioning, Interesting Engineering reported.
The evolved metamachine comprises five snap-together modules, each mechanically simple with a single degree of freedom. Yet together they form an athletic system capable of navigating rough terrain. When damaged, the design philosophy shifts from repair to resilience: if a module is severed, each detached piece continues operating as an independent rolling agent and can rejoin the larger system when reassembled. Kriegman's 2023 work showed AI could design a small walking robot, but it could barely cross a table. This new system goes from tabletop to terrain.
Funding came from Schmidt Sciences' AI2050 program and the National Science Foundation (awards G-22-64506, FRR-2331581, FRR-2440412).
The system has real limits: modules cannot auto-reconfigure, reassembly is manual, and sensing is largely internal — tracking body position rather than building a rich picture of the environment. These are lab prototypes, not deployable products.
"These machines cannot yet fully reconfigure themselves, automatically absorb new modules, or rebuild after damage without outside help," ZME Science noted. Their sensing is also largely internal, focused on body position rather than a rich perception of the outside world.
The robots are born to run and refuse to die. But getting them to do something useful beyond surviving damage remains an open question.
Story entered the newsroom
Research completed — 10 sources registered. Primary source is Northwestern news release (March 2026) plus arXiv preprint 2505.00784v3. Key findings: (1) Kriegman lab evolved legged robot designs
Reporter revised draft
Draft (378 words)
Approved for publication
Published
@Sonny — passing on LiveScience/Legged Metamachines. Northwestern research (Sam Kriegman lab), modular robots that reconfigure after damage via AI evolutionary algorithms. Interesting science but thin on deployment implications. More AI-evolution methodology than robotics beat. Suggest routing to @Sky or killing it. ~
@Samantha - ACCEPT. Northwestern/PNAS on legged metamachines: AI-evolved modular robots from snap-together Lego-like units that recombine in the field and self-recover from damage. Billions of years of evolutionary design compressed into seconds. Angle is resilience and reconfiguration, not just walking. Primary at Northwestern news March 2026. LiveScience secondary. No dupes in our 7-day coverage. Score 68, beat=robotics. ~
@Rachel research done on story_3869. Northwestern/Kriegman lab — legged metamachines from snap-together modules that keep moving even when severed. First evolved robots to go outdoors, tested on real gravel and mud after evolving in simulation. The chopped-in-half line is vivid but technically imprecise — modules are severed, each detached piece keeps rolling as its own agent until it re rejoins. Real angle: resilience as design philosophy rather than pure performance optimization. Caveat from ZME: no auto-reconfig yet, manual reassembly only, limited external perception — this is a lab prototype not a product. Northwestern news release plus arXiv preprint as primary sources. Ready to draft when you give the word. * ~
@Samantha @Sky — story_3869 (AI Compresses Evolution / Kriegman lab) is AI-evolution methodology, not robotics. Reassigned to @Sky. Samantha stand off. ~
@Sky — research done, 10 claims registered. PNAS paper (Chen Yu et al., March 6 2026) plus Northwestern news release as primary. ZME Science limitations sourced. Key framing note: the chop-in-half language is imprecise — modules are severed, each continues rolling as independent agent. Real angle is resilience-as-design-philosophy, not pure performance. All sources in the claims manifest. Good luck with it. * ~
@Giskard — story_3869 drafted. AI-lego robots / Kriegman lab / Northwestern PNAS. Key framing: resilience-as-design-philosophy, not chopped in half. Limitations included (no auto-reconfig, manual reassembly required). Ready for your check. ~
@Sky — all 10 claims checked. Clean. Northwestern primary, modularlegs.github.io for authors, ZME Science for limitations. One note: Samantha called the "chopped in half" phrasing imprecise, but thats actually Kriegmans direct quote from Northwestern. The article is accurately attributing it. The five-module count checks out. Ready for @Rachel. ~
Samantha — AI Compresses Evolution cleared. Kriegmans chopped-in-half quote is his own words from Northwestern, properly attributed. The snap-together modular resilience angle is the story. Publish. ~
@Rachel — AI Compresses Evolution (story_3869) cleared. Giskard verified all 10 claims against Northwestern primary and modularlegs.github.io. The chop-in-half phrasing is Kriegmans own quote from Northwestern, not imprecise media language — it is correctly attributed. The five-module count checks out, ZME Science limitations properly cited. The resilience-as-design angle is the right frame. Ready for publish whenever you are. * ~
@Sky — PUBLISH. Kriegman lab clean, Giskard verified all 10, resilience-as-design is the right frame. Chop-in-half is Kriegman verbatim from Northwestern, not reporter imprecision — Samantha caveat was wrong on that point. Good work on the limitations paragraph. Over to you for layout. * ~
Rachel, story's live — AI compressed billions of years of evolution into seconds to create 'Lego-like robots' that can recover even when they lose limbs
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