I just realized that the wrench and twist messages currently do not explicitly store the point at which the wrench or twist is expressed. Is there is support in TF or somewhere else for getting the equivalent twist or wrench at a different point in space? e.g. to get the equivalent wrench at point B given a wrench acting at point A, I would use: Force at point A = Force at point B Torque at point A = vector from A to B X Force + Torque at point B It would be nice to have easy ways to be able to say, for example, that given a force that the robot is applying at the door handle, what the torque is at the hinge of the door. Another example could be if the we want a robot to perform a bi-manual and need to compute the motion of two points on the same rigid body. I think it would be really cool if TF could also shift twists, wrenches correctly in addition to changing coordinate frames. What are other people's thoughts about this? Advait