[Question] Physical meaning of joint armature

[hojae-io]

Hi,

thanks for the great support for the code.

What is the physical meaning of "joint armature" of actuator?

I couldn't really find its meaning in the physx5 document as well.

Is it rotor inertia? Or something different?

If it is not equal to rotor inertia, is there any other variable designated for rotor inertia?

[hawkeyeking]

Hi Ho Jae,

I believe you're correct: that armature can refer to the rotor inertia for rotary electric motors.

From the documentation for the USD schema for rigid body physics used by PhysX in Omniverse:
"Conceptually, armature represents the inertia of an actuator driving the joint. Note that this parameter is used only when the joint belongs to an articulation. Range: [0, inf) Units: Linear joint - mass Angular joint - mass * (distance)^2"
Source: https://docs.omniverse.nvidia.com/kit/docs/omni_usd_schema_physics/106.1/class_physx_schema_physx_joint_a_p_i.html#ad1bd9404ccbc21b55e23fd91d288bbd9

Is that what you're looking for?

[preist-nvidia]

Stumbled on this, we have a bit more docs here now - the gear ratio should be considered in the computation: https://docs.omniverse.nvidia.com/kit/docs/omni_physics/106.5/dev_guide/guides/articulation_stability_guide.html#joint-armature