On 03/25/2016 03:30 PM, Nicklas Karlsson wrote: >> On 03/25/2016 01:26 PM, Nicklas Karlsson wrote: >>> 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 ------------------------------------------------------------------------------ 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
