Hi, My robot is composed of various coupled joints for dexterous hands, in which M joints are driven by N motors. I tried to find out how to express coupled joints in URDF but couldn't according to URDF XML reference. What I only found was PR2-specific element. Can this element express coupled joints and relationship between joints and actuators? If the element can't express coupled joints, any suggestion to do that will be appreciated. TIA - Yoonsoo