TX-34 NOVA · What the campaign taught us
These are results, not papers: measured in simulation, reproducible with one command, and not submitted to anyone. What follows is what we found — including the part where we were wrong.
Nobody has published this for a biped built on catalogue actuators.
38.2 N·m
Postural
89% of rated
29.8%
Of the cycle
contact transients
64%
Of the heat
from those transients
53 N·m
Touchdown target
to return to rating
The transient peak is governed by position-servo stiffness, not gait kinematics: raising the torque ceiling to ±200 N·m saturates that limit too, and the gait degenerates. The 80 N·m cap acts as a design limiter, not as a measurement of a requirement.
And the floor is honest: eliminating contact transients entirely would still leave the actuator at 89% of rating. The remaining lever is the lateral lean — a control strategy, not an actuator size.
A 5.5% mass increase does not degrade a platform uniformly. It destroys one regime and leaves another untouched.
Ballistic — jump height: −54%. Contact — landing pipeline: −100%. Walking payload: −100%, retracted — the canon gait falls under 100 g. Quasi-static balance envelope: unchanged. And at unchanged controller tuning, a 3.3% mass change cost 42% of the achieved steps.
The ballistic regime is mass-sensitive; support-polygon geometry is not. That distinction tells a designer exactly where a change will hurt and where it will not — and it is the honest answer to the first question anyone asks about a model with no CAD behind it.
Power loss on non-backdrivable gearboxes, three passive strategies compared.
Coasting leaves the head at 3.64 m/s at impact and takes 14.34 s to settle. Braking at ×5 or ×20 settles in 1.5 s — nearly ten times faster — but puts the head at 5.32 m/s, 46% faster, because the joint stops turn the collapse into a rigid fall. Each strategy wins on one criterion and loses on the other.
No passive strategy satisfies both criteria. It needs an active crouch or selective per-joint braking. This applies to any humanoid with non-backdrivable reduction, not only to this one.
This is probably the most transferable part of the work, and none of it was learned in advance. Each rule exists because something failed first.
Rule 01
Five times a headline figure changed for the same reason: the denominator contained time that did not belong to the phenomenon. Hip roll RMS was 43.1 N·m over the whole run and 53.7 in the steady-state window. Energy per step, being an integral over completed steps, did not move — which is how we knew the window was right.
Rule 02
Every module prints the mass of the model it actually loaded, with an assert. It exists because a whole batch once ran at 64.13 kg instead of 66.23, and the mass check — run separately from the tests — reported the right value of a different file. A check that runs apart from the test does not protect the test.
Rule 03
A seat reaction of 712 N on a body weighing 650 N. Impossible in quasi-static equilibrium. Cause: summing the magnitudes of contact forces instead of the vertical component, over a window placed in the descent. Every measured force now carries its closure check as a permanent assert.
Rule 04
The model was running with the hip 12° beyond the software limit. Once aligned, squat depth went from 0.48 to 0.60 m — the true value was worse than the published one — and sit-to-stand went from pass to fail before a different strategy recovered it.
Rule 05
Posture tables declared poses "verified against joint ranges". That is a kinematic check: it says the joint reaches the pose. Simulation found reachable poses that fall over.
Rule 06
An automated consistency checker declared the corpus clean while two withdrawn claims were still presented as achieved. Two causes: the forbidden-value list had been built from the memory of what was changed rather than from the list of dead claims, and exemptions had been widened until "clean" was reached. Now the tool must prove it can find — deliberately injected values, before any clean result counts.
Rule 07
On two hundred pages, two automated passes produced two new defects while correcting others: a retirement note made self-contradictory by a substitution applied inside it, and a withdrawn claim made more credible by replacing "certified" with "computed in simulation". Past a certain size, correct one at a time and then freeze.
Rule 08
A fixed joint between base and pelvis was being merged into the world by the exporter: 5.4 kg of pelvis evaporated from every URDF ever produced — 57.4 kg declared against 62.8 real — and no tool flagged it. Every derived artefact is now re-read and checked for mass and joint count, not just generated.
Two claims withdrawn
The landing pipeline — 0.36 s to upright rest — and the toe-brake multiplier of ×3.9 were measured at 62.8 kg and did not survive the correction to 66.23 kg. Both go to zero.
They are mass-sensitivity findings, not measurement errors, and they would return only with a dated re-measurement. They are declared as withdrawn in the repository README, in the technical document, and here. A campaign that does not publish its retractions is not worth checking.
Formulated as questions, not requests. If you have data on any of these, it would be useful.
Every figure on this page is reproducible with one command from github.com/SynthMike34/nova-sim — Windows and Linux agree within 0.5% on the torque metrics, with an identical sample count. No result has been validated on physical hardware, and none of this has been peer reviewed. It is offered as it is: measured, declared, and open to being checked.