This encoder is a serial 17-bit with 4 wires. 0V, 5V, T+ and T- On Thu, Sep 19, 2019 at 11:26 AM Todd Zuercher <to...@pgrahamdunn.com> wrote:
> Or to think of it another way, closing the loop with a force meter, would > be analogous to the air regulator on an air counterbalance. > > Todd Zuercher > P. Graham Dunn Inc. > 630 Henry Street > Dalton, Ohio 44618 > Phone: (330)828-2105ext. 2031 > > -----Original Message----- > From: Todd Zuercher <to...@pgrahamdunn.com> > Sent: Thursday, September 19, 2019 8:32 AM > To: Enhanced Machine Controller (EMC) <emc-users@lists.sourceforge.net> > Subject: Re: [Emc-users] ADC - realtime for load cell > > I don't think closing the loop with force feedback would work, If the > motor is applying x amount of force, adding more weight isn't going to > change the amount of force read by the force feedback device. It will just > push it down. The feedback will only be reading the force applied by the > motor to resist the load, not the load itself, so changing the load will > only cause acceleration. > > Todd Zuercher > P. Graham Dunn Inc. > 630 Henry Street > Dalton, Ohio 44618 > Phone: (330)828-2105ext. 2031 > > -----Original Message----- > From: Chris Albertson <albertson.ch...@gmail.com> > Sent: Wednesday, September 18, 2019 8:31 PM > To: Enhanced Machine Controller (EMC) <emc-users@lists.sourceforge.net> > Subject: Re: [Emc-users] ADC - realtime for load cell > > One way to measure force is with a spring. Force is measured by looking at > spring displacement. It is kind of like the load cell idea but you use > a spring scale. > > Another way that is not quite to accurate is to measure the current in the > motor. Current is proportional to torque. > > On Wed, Sep 18, 2019 at 4:39 PM Curtis Dutton <curtd...@gmail.com> wrote: > > > my experiment is to use a force measuring device to proportionally > > control torque output on a servo attached to a ball screw. > > > > as a thought experiment imagine a platform hoisted by said ball screw. > > as you added weight to the platform the motor torque would increase to > > offset the weight and keep it steady. or you could set the required > > force equal to X kgs and with less than X kgs on the platform it would > > travel up proportionally. the motor would increase torque to maintain > > the force value. if more force than X the platform would travel down > proportionally. > > the motor would decrease torque to maintain the set force value. > > > > in effect not a position commanded but a force commanded linear actuator. > > > > is there some othere device that would be better for this type of > > force measurement? in the 0 to about 500kg range. > > > > On Wed, Sep 18, 2019, 11:51 AM Chris Albertson > > <albertson.ch...@gmail.com> > > wrote: > > > > > in any case, even with lower 16-bit precision, the most important > > > part of the design is the analog portion that sits between the load > > > cell and the A/D converter. > > > > > > > > > > > > On Wed, Sep 18, 2019 at 6:38 AM Curtis Dutton <curtd...@gmail.com> > > wrote: > > > > > > > Chris thanks for the info. > > > > > > > > I'm not exactly certain at this point what precision I need. I'll > > > > be determining that experimentally later. I will keep in mind what > > > > you > > have > > > > said, I'll deal with it after I get my hardware running. > > > > > > > > > > > > On Tue, Sep 17, 2019 at 6:17 PM Chris Albertson < > > > albertson.ch...@gmail.com > > > > > > > > > wrote: > > > > > > > > > If you want better than 16-bits and 1KHz then you also are going > > > > > to > > > need > > > > a > > > > > very good quality analog signal conditioning and instrumentation > > > > amplifier. > > > > > The analog circuit between the A/D converts and the load cell > > really > > > > does > > > > > matter. You have to reject common-mode or the low bits will > > just > > > be > > > > > filled with 60Hz noise. And you can not simply use a "brick wall" > > > filter > > > > > or you will not get the desired bandwidth through. (If you are > > needing > > > > to > > > > > sample at 1K then you must care about 500Hz bandwidth. > > > > > > > > > > This matters a LOT more than which A/D chip you use. > > > > > > > > > > 22 bits is better than one part per million. Do you really need > that? > > > It > > > > > will be hard to isolate all of the electrical and mechanical > > > > > noise especially > > > > > > > > > > On Tue, Sep 17, 2019 at 2:26 PM Curtis Dutton > > > > > <curtd...@gmail.com> > > > > wrote: > > > > > > > > > > > I have a pet project I'm starting that will involve reading a > > > > > > load > > > cell > > > > > in > > > > > > as near as real time as possible and using that input for > > > > > > servo > > > > control. > > > > > > > > > > > > I plan on using mesa hardware to interface to the equipment. > > > > > > Does > > > > anyone > > > > > > know of a nice way to interface hotsmot2 to a load cell? > > > > > > > > > > > > I would like a fairly high resolution. 16 bit minimum, the > > > > > > higher > > the > > > > > > better up to 22 bit I suppose. As well as the ability to > > > > > > sample at > > > the > > > > > > servo thread rate of 1 Khz. > > > > > > > > > > > > > > > > > > Thanks, > > > > > > Curtis > > > > > > > > > > > > _______________________________________________ > > > > > > Emc-users mailing list > > > > > > Emc-users@lists.sourceforge.net > > > > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > Chris Albertson > > > > > Redondo Beach, California > > > > > > > > > > _______________________________________________ > > > > > Emc-users mailing list > > > > > Emc-users@lists.sourceforge.net > > > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > > > > > > _______________________________________________ > > > > Emc-users mailing list > > > > Emc-users@lists.sourceforge.net > > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > > > > > > -- > > > > > > Chris Albertson > > > Redondo Beach, California > > > > > > _______________________________________________ > > > Emc-users mailing list > > > Emc-users@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > -- > > Chris Albertson > Redondo Beach, California > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
