I also use hal to do temp compensation using the offset component. https://www.youtube.com/watch?v=h-CdFd2Zakc
sam On 7/27/2015 9:34 AM, Sebastian Kuzminsky wrote: > On 07/26/2015 09:31 PM, Brian wrote: >> I have had an idea lingering in my head for quite some time now. How about >> moving the screw/backlash comp out of motion and implement it with a HAL >> module. The purpose would be for two goals. One it would make it more >> logical to implement more sophisticated joint compensation, such as thermal >> expansion, deflection, and belt stretch. Second, it would set the stage to >> be more friendly for dual scale/motor feedback, because it would give >> control over where the compensation is added in the feedback loop. > I agree with Andy, backlash compensation belongs in Motion, since that's > where the trajectory is planned. > > Motion can insert a backlash compensation "move" when a joint changes > direction, and compensate for the time that the backlash move takes by > not moving the other joints (except that possible backlash moves on > other joints may happen at the same time). > > An external hal component that tried to do that would have to capture > and buffer all the joint waypoints that Motion was generating during the > backlash move, then when the backlash move is finished either try to > catch up to Motion (which would violate the accel & vel that Motion had > planned), or stay behind Motion from then on out (which would introduce > lag on things that immediately affect the trajectory, like Feed Override). > > While backlash compensation surely belongs in Motion, slow, > small-magnitude, long-term offset changes like thermal compensation can > probably be implemented safely as a HAL modification to the waypoints > commanded by Motion. See Dewey's "moveoff" demo for an example of how > this can be implemented (sim/axis/moveoff), with some video here: > > https://www.youtube.com/watch?v=KY6hx7WBkO8 > https://www.youtube.com/watch?v=XGDq6620fPQ > > ------------------------------------------------------------------------------ _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
