On Fri, 25 Mar 2016, Sebastian Kuzminsky wrote: > Date: Fri, 25 Mar 2016 13:35:46 -0600 > From: Sebastian Kuzminsky <s...@highlab.com> > Reply-To: "Enhanced Machine Controller (EMC)" > <emc-users@lists.sourceforge.net> > To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> > Subject: Re: [Emc-users] Encoder failure > > 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. >
One type of encoder failure that is not detected by the following error is runaway when static. This is typically not as much of a problem with velocity mode drives since the commanded velocity is 0 so its more of a creep-away problem. But for torque mode drives, a broken encoder when static can result in a residual error being integrated up to full torque and resulting in a full speed runaway. This can be detected by looking at the PID saturated pin and faulting if set for too many successive samples. > > -- > 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 > Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your (")_(") signature to help him gain world domination. ------------------------------------------------------------------------------ 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
