Grant (@grantg07) header
Grant (@grantg07) profile picture

Robotics

New York, NY
Joined January 2025
Hmm. Quite a bit of changes since H2 actually. Knee is now directly actuated at the joint again compared to H2 (Linkage Driven). Guessing the linkage constrained deep flexion + more failure points. Near neutral hip abduction actuator(J1) vs a high anhedral angle for the old H2. They’ve managed a much more compact hip box than G1, potentially improving inward adduction clearance for crossover stepping without needing an anhedral angle. Ankle looks to have returned to G1's dual pushrod parallel linkage arrangement, rather than H2's cables for roll / push rod for pitch arrangement. Shin packaging is noticeably more compact, possibly enabled by longer linkages while preserving ankle ROM. Parallel linkage setup also brings back torque sharing for ankle pitch. Dual hot swappable batteries (back face rather than side face extraction) Surprising how much the leg architecture is still changing within Unitree’s designs vs the Arm still being serial. Would’ve expected more convergence by now, especially with kinematic codesign (Though I'm sure other factors play a role too).
Unitree Introducing: H2-X Kung Fu Legend Guardian🤖 Powerful performance to serve and guard you, with a maximum endurance of approximately 8 hours. Please use the robot safely and in a friendly manner.
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What if one of the biggest bottlenecks in robot learning isn’t the policy, but the robot arm itself? In sim, OpenArm misses 64% of the UMI episodes. YAM 42%. Axol 29%. I searched 5,040 tabletop arm designs (red in the video = a miss). The best one misses just 9%, with 9 to 21× lower tracking error and 6 to 11× lower joint-speed penalties than those three arms. And even when the other arms can replay a demo, they still pay for it: 8 to 15× higher smoothness penalties and 7 to 33× higher singularity-conditioning penalties. Caveats: sim only, same controller for every arm, no learned policies tested yet. Full methodology in the article. Makes me wonder how much arm kinematics biases which behaviors policies can actually learn from human demonstrations.
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Anyone tryna talk UMI grippers? Been thinking through the optimal architecture. Generalist's gear based gripper allows for the smallest form factor, but locks you into small servos, and removes the parallelism in gripping (Unsure how important parallelism really is? With the compliant finger tips they use, it absorbs the error) One linear rail, dual carriage gear based/linkage based gripper allows for very thin height, but sacrifices width. (Worst design IMO? The extra rail length makes it easy to catch on objects) Two linear rail, dual carriage gear based/linkage based grippers allows for low width, but sacrifices height. Trigger based designs sacrifice fine grain movement, human affordances, and form factor sizing. With the parallel jaw grippers its simpler to make it work for production with one 10Nm actuator vs gear based grippers generally use servos to not sacrifice form factor (which has torque issues depending on the task and cycle life issues depending on servo) However, with the parallel jaw grippers, its much harder to make a non trigger based design with the same width profile as Generalist, as the extra height with the dual linear rail sacrifices ergonomics. To me it seems like Generalist and 2 Linear rail dual carriage designs is the best, but the 2 Linear Rail design requires a non straightforward, heavier UMI design.
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Ngl, this could be the endgame archetype for data gloves Beats cameras on occlusion, IMUs on drift, EMF on interference, and exoskeletons on mechanical complexity Mean fingertip error is ~4.9 mm, but most of that seems solvable: calibration, glove fit, and hand model error
光ファイバーを編み込んだ手袋で、指の動きをカメラなしで正確に記録できるようになりました。 人の手の動きをロボットの学習データにする方法は2つありました。カメラで撮る方式は物や手そのものに隠れると使えず、明るさにも左右されます。磁気センサ式の手袋は時間とともに値がずれていきます。 この手袋はファイバーの曲がり方から形を読み取るため、どちらの弱点も避けられます。精度はモーションキャプチャに並びました。遠隔操作でデータを集める工場のような取り組みに直結します。
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This is insane value now that the J288 servo is $89. FOC brushless, dual encoders, Impedance control, Torque telemetry Its closest Dynamixel (XC430, $138): brushed, single encoder, position control only Servos are finally getting an architectural upgrade
Microduck is a really fun robot. We highly recommend giving our brushless digital servo a try. 🥰🥰unitree.com/DigitalServo
Readers added context they thought people might want to know
Microduck is not using Unitree's Servo. x.com/matth_lapeyre/…
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Both robots’ legs converged on essentially the same architecture: hip rotation → abduction → flexion, two actuators stacked at the hip flexion axis, one driving the hip and one driving the knee through a linkage, and the ankle driven by linkage from actuators at the knee. All of it pulls actuator mass proximally, reducing distal leg inertia during swing. The gap probably doesn’t come from the overall leg topology. It’s mass distribution, actuator design, linkage geometry, the arms, limb lengths, and the policy.
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So: Lightning’s opportunity is more force and impulse per contact without killing cadence. Tiangong’s is higher cadence and better acceleration without losing stride. Different optimization problems. Both Chinese. America isn’t in this race yet.
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Grant retweeted
Goat team, lots lots of work to be done though. Currently working on laying out the below within the Torso. Main Battery PDB (Power Dist. Board) Main Compute (Jetson Thor) Rockchip Ethercat Hub ZED Link Capture Card Quad
V0 Draft of our humanoid’s skeleton minus the head 😁
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Unitree G1 knee actuator teardown for anyone curious! Slot/pole count, rotor and stator dimensions, air gap, magnets, gear tooth counts, and the full bearing stack, all measured with photos. Full Teardown: docs.google.com/document/d/1…
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Feels like the NBA all star 1v1 problem lmao, the top guys have everything to lose and nothing to prove so they no show. Been thinking about starting a college humanoid competition, but it’d lowkey just be Chinese actuator farming. And you can’t even prototype around it with one humanoid being ~30 actuators.
I wish we were doing this kind of stuff in the US, we've become way too serious
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a 10 minute application for a $50,000 fellowship. no strings. a total of $1,000,000 going out, towards making more magic in the world. presenting the Basis Fellowship. run by @markkhrapko ,@thewildstevenp , and spencer green
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Anyone have any thoughts on the rollout results? The overall real world results seems pretty skewed by lockbox key turning task. It goes 0%/0%/0% -> 90% (n=10). If you remove that task, the mean normalized score gap drops from 8.1 points to 1.8 points Would love to see more real world rollouts to see how robust the 100k - 1M scaling trend is on robot
Today we are introducing Dyna-2, a world-action model pre-trained on one million hours of human video. At this scale, for the first time, we discovered several new scaling laws: • world-action models exhibit scaling law on human data across four orders of magnitude, from 1000 to 1,000,000 hours, • this human data scaling law implied a scaling law on never seen robot data, • both data and objective matter; world modeling and scaling on video data are essential for cross-embodiment scaling transfer to emerge 🧵
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Grant retweeted
🤝 Effective human-robot collaboration often requires robots to infer human intent, coordinate their timing, and know not only 𝘸𝘩𝘢𝘵 action to take, but 𝘸𝘩𝘦𝘯 to assist. In this work, we study whether modern Vision-Language-Action models can learn collaborative behavior directly from demonstrations, without hand-engineered intent recognition or planning pipelines. Introducing “𝙇𝙚𝙖𝙧𝙣𝙞𝙣𝙜 𝙩𝙤 𝘼𝙨𝙨𝙞𝙨𝙩: 𝘾𝙤𝙡𝙡𝙖𝙗𝙤𝙧𝙖𝙩𝙞𝙫𝙚 𝙑𝙇𝘼𝙨 𝙛𝙤𝙧 𝙄𝙢𝙥𝙡𝙞𝙘𝙞𝙩 𝙃𝙪𝙢𝙖𝙣-𝙍𝙤𝙗𝙤𝙩 𝘾𝙤𝙡𝙡𝙖𝙗𝙤𝙧𝙖𝙩𝙞𝙤𝙣,” with Letian Li, Alex Cuellar, and @hagenowrobotics. ✨What we found: ✅ VLAs can learn collaborative behavior across real-world tasks involving sequential collaboration, handovers, and implicit human intent. 🚨 But collaboration exposes a timing failure mode we call 𝙙𝙚𝙢𝙤𝙣𝙨𝙩𝙧𝙖𝙩𝙞𝙤𝙣 𝙖𝙘𝙩𝙞𝙤𝙣 𝙡𝙚𝙖𝙠𝙖𝙜𝙚. Because many VLAs predict chunks of future actions, a training chunk can cross from waiting into handover. As a result, the robot may begin assisting before the human is ready, causing premature actions, drift, and failures. To address this, we introduce an inference-time steering method that keeps the robot near demonstrated waiting states until the human shows readiness, requiring no retraining. Across our experiments, steering reduced premature handovers by 96.7% in our false-commitment study. In a 16-participant user study, steering enabled smoother, longer-horizon robot behavior while reducing task time and avoiding premature assistance. For more details on the approach, experiments, and results: 📄 Paper: arxiv.org/abs/2606.12475 🎥 Video: youtu.be/HRycLQUMZok We are grateful to @tutorintel for donating the robot hardware used in this project.
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We're WiscoHumanoids, we just launched this year in January and we've already made a ton of progress to showcase in the UW-Madison yearly Engineering Expo! Our club has three main groups—Mechanical, Electrical and Software:
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Goat team, lots lots of work to be done though. Currently working on laying out the below within the Torso. Main Battery PDB (Power Dist. Board) Main Compute (Jetson Thor) Rockchip Ethercat Hub ZED Link Capture Card Quad
V0 Draft of our humanoid’s skeleton minus the head 😁
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29 DOF, 4’5 currently. Likely going to add 2 neck DOFs to match the exact camera perspective of a human user collecting data with UMI.
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