Marcus, > I just submitted an enhancement patch (#5063) for the pr2_mechanism_model > package, which adds a new helper class for trees. This class is derived from > and structured like the one for chains written by Stuart Glaser and Wim > Meeussen. I hope, it is a useful contribution. Please let me know, if you > like me to apply changes! This is great! Working with kdl tree structures gets a lot easier when you can easily get access to the state of the tree. I'd vote to get this added to the pr2_mechanism_model package. If there are no objections I'll apply the patch to trunk, for inclusion in Electric. Thanks for your contribution! Wim -- -- Wim Meeussen Willow Garage Inc.