Does the assembly order change the arm an arm needs to build its own gripper?

What it found

Combines the order search of robofab-selfparts (384 valid orders) with the two-link reach model of robofab-reach, letting each part’s lift height clear whatever is already assembled. Negative result: for every valid order the shortest arm is the same (for example 80 mm per link at a 100 mm shoulder and 120 mm tray gap, 120 mm at a 200 mm shoulder), because the cover’s own lift point bounds every order and the tray distance dominates. Stylised: wrist point only, 10 mm link grid, 20 mm base grid.

Paper, code and results

• README and method
• Experiments and results
• Code
• Tests

More in Robot manufacturing loops

• Can friction hold each printed part of a gripper?Can friction hold each printed part of the toy gripper? The simulated minimum jaw force matches the m·g/(2μ) bound to within 5% over 33 cases and is at most 0.1 N, so the jaw opening, not friction, is the constraint (stylised).
• Does arm torque or jaw friction limit how fast an arm carries a printed part?Does arm torque or jaw friction limit how fast an arm carries a printed part? With 0.12 m links and 5 N m the carries take 0.06–0.10 s and the cover needs 1.25 N per jaw (21× static); grip binds below about 0.5 N (stylised, bound extrapolated beyond 40 m/s²).
• How much carry time does a time-optimal move save over min-jerk, and what does it cost the jaws?How much carry time does a time-optimal move save over min-jerk, and what does it cost the jaws? On the robofab-armaccel arm the six-part total falls by 21 to 29% while the jaw-force bound rises 1.2 to 2.4 times (stylised, assumed parameters).
• How fast can an arm carry a printed part when the jaw force is capped as well as the joint torque?How fast can an arm carry a printed part when the jaw force is capped as well as the joint torque? On the robofab-armbang arm the time-optimal move still beats min-jerk by 17 to 43% under caps of 1.25 to 10 times the static hold force, and a tight cap makes the torque limit irrelevant (stylised, assumed parameters).
• Does a joint-speed limit erase the time-optimal carry's advantage over min-jerk?Does a joint-speed limit erase the time-optimal carry's advantage over min-jerk? On the robofab-jawcap arm it grows it: 28 to 46% shorter under speed limits of 6 to 1 rad/s, tending to the 47% set by the min-jerk profile shape (stylised, assumed parameters).
• Is the time-optimal carry's speed-limited advantage just the min-jerk profile's shape?Is the time-optimal carry's speed-limited advantage just the min-jerk shape? Against a tuned trapezoidal-velocity move it is only 0.4 to 2.9% at speed limits of 2 and 1 rad/s (46% over min-jerk), and 8.7 to 22.5% with no speed limit (stylised, assumed parameters).

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Proper scoring & elicitation28Effort & peer prediction9Verification games & slashing19Detection & tolerances14Markets as routers13Prediction-market design9Paying contributors8Decentralised training systems23Digital twins & sim-to-real164LLM chip design loops40Robot manufacturing loops53Ambient AI assistant46Self-replicating manufacturing34Simulation-first design64Engineered clothing45Task-specific AI accelerators40Algorithmic chip-design loops42Open-source purpose-built robots44The software-engineering loop43Adversarial human imitation41Open-source residential construction41Autonomous multi-angle capture34Sensing, imaging and 3D31Energy supply and dense energy storage39Robot societies among people31Agentic co-design of low-cost robots27Laundry-hanging robots25Machine learning on qualitative data23Robots on the building site27Civilizations & group psychology1History & human sciences1

Produced with AI assistance (Claude). Results are from the code in this repository and are simulated or stylised unless the abstract says otherwise; nothing here implies affiliation with or endorsement by any lab, researcher or company cited. MIT licensed.