| name | move-torso |
| description | Bends, leans, and twists the upper body using the spine and chest — bowing forward, leaning back or to the side, and rotating/twisting the torso. Use whenever a command mentions torso, waist, spine, back, chest, bend over, bow, lean, hunch, slouch, straighten up, or twist/rotate the body (without turning the feet). |
| category | torso |
| disable-model-invocation | true |
move-torso
Atomic primitive for the Spine and Chest joints (the lower and upper
torso). Both are world-aligned at rest ([0,0,0]): local +X = world right,
+Y = up, +Z = forward. Angles are ABSOLUTE local euler [x,y,z] deg, XYZ.
Split the bend across BOTH joints for a smooth curve (the totals below are
Spine+Chest combined; a rough 50/50 split reads well, or weight more onto Spine
for a deeper hinge).
Axes (world result)
- Bend forward ↔ back (flexion/extension): X axis. POSITIVE X bends the torso
forward (a bow); NEGATIVE X leans back. Bow ≈ +50–80° total; gentle
lean back ≈ −20°.
- Lean side to side (lateral flexion): Z axis. POSITIVE Z leans toward its
left; NEGATIVE Z toward its right. ≈ ±35°.
- Twist (axial rotation): Y axis. POSITIVE Y rotates the chest to face toward
its right (+X); NEGATIVE Y toward its left. ≈ ±45° (this twists the torso
without moving the feet — to turn the whole body use
turn-and-face).
Recipes
- Bow / take a bow:
Spine:[30,0,0], Chest:[30,0,0] (≈60° forward). Pair
with a say and consider a short hold.
- Lean back / look up at the sky:
Spine:[-12,0,0], Chest:[-12,0,0].
- Lean to the right:
Spine:[0,0,-18], Chest:[0,0,-15].
- Twist to the left:
Spine:[0,-22,0], Chest:[0,-22,0].
- Slouch / hunch: small forward
Chest:[18,0,0] plus a slight Neck tip.
Worked Actions
- "take a bow" →
{"durationMs":1000,"pose":{"Spine":[32,0,0],"Chest":[30,0,0]},"say":"Thank you!"}
- "lean to your left" →
{"durationMs":600,"pose":{"Spine":[0,0,18],"Chest":[0,0,15]}}
- "twist your upper body to the right" →
{"durationMs":700,"pose":{"Spine":[0,22,0],"Chest":[0,22,0]}}
Limits & posture
Keep total spine flexion within ~|80|, lateral lean ~|35|, twist ~|45|. A deep
forward bow shifts the center of mass forward — for big bends consider a small
counter-flex at the hips/knees and keep both feet grounded (see
balance-and-posture). Emit only Spine/Chest here.
