duck-under

name	duck-under
description	Ducks low and moves forward under a low obstacle, then stands back up, via a translating sequence that dips root.y. Use when a command mentions duck under, go under, limbo under low, crouch under the bar, or pass beneath something.
category	locomotion
disable-model-invocation	true
subskills	["bend-knees","move-torso","balance-and-posture"]

duck-under

Drop into a deep crouch (root.y~-0.4), travel forward under the obstacle, then rise.

Composes: bend-knees + move-torso + balance-and-posture

How

• Use a sequence with loop:false. Frame root is ABSOLUTE; compute the travel axis from state.position+state.faceDeg (0=+Z, 90=+X). The example assumes origin facing +Z.
• Deep crouch with a forward torso (Spine+X~30) and bent legs; advance z; then return to rest and root.y:0.
• durationMs ~1800.

Example

• "duck under it" -> {"durationMs":1800,"say":"Ducking under.","sequence":{"loop":false,"frames":[{"t":0,"pose":{"LeftUpLeg":[55,0,0],"LeftLeg":[80,0,0],"RightUpLeg":[55,0,0],"RightLeg":[80,0,0],"Spine":[30,0,0]},"root":{"y":-0.4,"z":0.3}},{"t":0.5,"pose":{"LeftUpLeg":[55,0,0],"RightUpLeg":[55,0,0],"Spine":[30,0,0]},"root":{"y":-0.4,"z":0.9}},{"t":1,"pose":{"LeftUpLeg":[0,0,180],"LeftLeg":[0,0,0],"RightUpLeg":[0,0,180],"RightLeg":[0,0,0],"Spine":[0,0,0]},"root":{"y":0,"z":1.4}}]}}

Limits & posture

Keep ≥1 foot grounded except at a jump's airborne apex; stay inside human joint ranges and keep weight over the support — see balance-and-posture.