> >>> As someone mentioned before a the an axis/joint may/will run away > >>> in case of an encoder failure. > >>> > >>> It would be possible to detect an encoder failure by comparing > >>> output signal with encoder signal. A velocity signal may be > >>> integrated and do not allow to wander to much or an encoder error > >>> will be detected. A torque signal would be worse. > >> > >> An encoder that fails into runaway (motion erroneously detected > >> when none is occurring) or that fails into stop (no motion detected > >> when motion *is* occurring) will both result in a following error, > >> precisely for the reason you say above: linuxcnc compares the > >> commanded position with the feedback position from the encoder. > >> > >> > >> -- Sebastian Kuzminsky > > > > No if no motion is detected and there is a small error linuxcnc will > > output a signal to correct it and machine start to move. Since no > > feedback is detected integrator will turn up speed and machine run > > away. > > Are you describing a scenario where the signals from the encoder are not > getting to LinuxCNC? So it always looks to linuxcnc like there is no > motion happening, no matter what's actually happening in the motion > hardware? > > In that situation, if LinuxCNC is "at rest" and not commanding any > motion, it's true that any small PID output will be applied forever, > with no change in the feedback, and the motor will run away. > > And you're suggesting to look at the PID output, and if it's commanding > motion but the encoder is reporting no motion, then trigger some sort of > "hardware malfunction" estop? > > That sounds like it would work. > > > -- > Sebastian Kuzminsky
Yes I am suggesting comparing the PID output and encoder input. Nicklas Karlsson ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785351&iu=/4140 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
