mino.mobi / biome / sprite lab / myology lab / balance lab

balance lab — a standing, self-righting quadruped

The myology lab grew muscles that hold a pose; this asks the harder question — can the skeleton stay up on its own against gravity, in real time? It runs a balance controller (Virtual Model Control, the method real legged robots use): treat the trunk as one rigid body, decide the wrench — force + torque — it needs to hold its height and stay level, then solve for the ground-reaction forces the planted feet must push with to produce it (least-squares, clamped to a friction cone). Shove it and it recovers from the state error; turn the legs off and only gravity remains, so it drops. It also walks: a 4-beat gait with Raibert foot placement, the cadence auto-coupled to speed so the steps stay short and brisk — that keeps the feet under the centre of mass, which is the stable regime. Push the speed past the slider and the trunk would still tip — capture-point control is the next layer.

creature

stance
—
trunk mass
—

mode

perturb

state

height err
0.0
pitch
0.0°
feet down
4 / 4
advance
0
CoM speed
0
total GRF
—
skeleton planted foot swing foot ground force centre of mass
What you're watching. The thin grey figure is the literal skeleton (from comparative-osteology data), rigidly carried by the controlled trunk. The thick struts are the legs, posed by two-link inverse kinematics from each hip down to where the controller decides the foot should be. Green arrows are the ground-reaction forces the balance solve asked each planted foot for — note they always sum to hold the body's weight and cancel its tipping torque. Each drawn leg is clamped to its real bone length, so a strut can never stretch. The whole thing is deterministic from the iNaturalist taxon id, so a given creature balances the same way on every machine. Walking holds its pitch across the whole speed slider because cadence rises with speed; the honest edge is past that range, where capture-point control would take over.