Hi Yoonsoo,
Seems like a custom transmission should work here. You wouldn't have to specify anything additional in URDF, except adding a transmission block for corresponding joints. Modeling your custom transmission after SimpleTransmission or WristTransmission should be a good starting point.
Are you planning to run on hardware or in simulation?
John
Thanks for your kind reply, John.Let me try to explain simply how joint/actuators are coupled in my robot.There 6 groups of coupled joints per a hand and all groups of 2 joints are driven by 2 motors and transform matrix(2x2 or 3x2) from joint angle/velocity/torque to motor angle/velocity/torque can be expressed in terms of some ratios and vice versa.How can I express this relationship in URDF? Should I implement some supporting classes specific to my robot similar to PR2's SimpleTransmission, WriteTransmission, and PR2GripperTransmission? It may be helpful to understand how the PR2-specific transmission element is designed?- Yoonsoo2010/10/14 John Hsu <johnhsu@willowgarage.com>Hi Yoonsoo,
URDF does not support coupled joints. Custom transmissions should most likely be able to do what you have described. pr2_mechanism_model has some examples and documentation on how transmissions are used in PR2.
How are the joint/actuators coupled in your robot?
Thanks,
JohnOn Tue, Oct 12, 2010 at 11:02 PM, Kim, Yoonsoo <yesarang.kim@gmail.com> wrote:
_______________________________________________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 <transmission> element. Can this <transmission> 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
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