Chain & Effector definitions

Body , Chains and Effectors in one glance:

https://developers.softbankrobotics.com/sites/default/files/repository/56_html_nao/_images/almotion_names_pepper.png
Body
= all Joints + the 2 Actuators ( RHand and LHand ) added at the end of the arm links.

Chains

A Chain may contain:

  • the Joints of a limb ( Head , Leg ) or
  • the Joints + the Actuators of a limb ( LArm , RArm ).

The table below lists the chains and all the Joints and Actuators included in each:

Body is ... Head + LArm + Leg + RArm
The chain ... Head LArm Leg RArm
involves ... HeadYaw LShoulderPitch HipRoll RShoulderPitch
HeadPitch LShoulderRoll HipPitch RShoulderRoll
LElbowYaw KneePitch RElbowYaw
LElbowRoll RElbowRoll
LWristYaw RWristYaw
LHand RHand

Effectors

Effector
= Torso + the extremity of each limb. Limb Effector names are identical to the corresponding Chain names.
https://developers.softbankrobotics.com/sites/default/files/repository/56_html_nao/_images/motion_effectors_pepper.png

Effector positions are defined in relation to the position of the last joint of the chain.

Effector name Position End transform Related to ...
Head At the neck joint Position3D(0.0, 0.0, 0.0) HeadPitch
Torso A reference point in the torso Position3D(0.0, 0.0, 0.0) Torso
LArm Inside the hand Position3D( HandOffsetX , 0.0, - HandOffsetZ ) LWristYaw
Leg Wheel center, at floor level Position3D( WheelCenterOffset , 0.0, TibiaLength + WheelRadius ) KneePitch
RArm Inside the hand Position3D( HandOffsetX , 0.0, - HandOffsetZ ) RWristYaw