MuJoCo Sandbox · engineering journals · 2026

Robots built, broken and measured in simulation

Seven projects in MuJoCo, from a needle placing 40 µm threads to a dog walking on three legs. Each journal tells what was built, what failed and what was measured, with the films of the recorded runs. Motion always comes from the physics; each journal says which parts are learned and which are programmed.

Learned · PufferLib 5.0 · RTX 4090

Surgical thread robot

A gantry needle places 40 µm threads at site after site under workcell, sensing and tissue disturbances; a learned policy lands them a median 8 µm from target.

reinforcement learningelastic rodinteractive replay

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Learned · PPO · MuJoCo Warp · RTX 4090

Adaptive dog

One PPO policy walks a Unitree Go2 healthy or missing a leg, then stands and balances; one GPU relearned it all from random weights in 22 min 05 s.

reinforcement learninglimb lossGPU physicsbalance

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Learned forecasts · NeuralOperator · RTX 4090

Neural wind delivery

A quadrotor carries a slung parcel through simulated Navier–Stokes wind; learned wind forecasts cut its tracking error from 10.89 cm to 4.28–4.42 cm, and all 24 standard deliveries land.

neural operatorspredictive controlcable payloadfluid simulation

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World models · JEPA · RTX 4090

JEPA drone world models

A drone world model rebuilt from a paper makes a hand-written controller track more accurately; then a MuJoCo gym puts new JEPA architectures to the test, with 1,344 learned-model flights and zero contacts.

world modelsJEPAMPPI controlRust + CUDA

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RC rovers · simulated LoRa · Reticulum

Radio-linked rovers

Six rovers share what they find over a simulated radio: no duplicate inspections with a healthy link, and no faster finish.

MuJoCoLoRa packet modelReticulum 1.5.2rule-based agents

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Scripted · MuJoCo · Go2 stand-in

Amphibious quadruped

A Go2 model with four thigh-mounted floats walks into a basin, floats 10.8 s with no ground contact and climbs out on the far bank.

buoyancy modelscripted crawlidealised thrustersland to water to land

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Scripted · MuJoCo Menagerie · ripple gait

Hexapod transporter

Six legs and two Kinova arms: grasps a mug and a block by finger contact, walks around a barrier and places both 6.2 and 16.5 mm from their marks in 112.9 simulated seconds.

scripted controlmobile manipulationcontact graspingsix camera views

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