So you want to balance the load on the platform with a single load cell?
That's going to be nearly impossible.
The reason is that when you drive the load up, the load cell will see an
increase in force due to acceleration.
So you will need some position feedback as well.
Dave
On
On Thu, 19 Sep 2019 at 18:13, Curtis Dutton wrote:
> This encoder is a serial 17-bit with 4 wires. 0V, 5V, T+ and T-
That might be another puzzle. Mesa has a UART module, but that seems to
only want data in 8-bit bytes.
--
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
That encoder is probably using a custom protocol and can only be used
with systems specifically designed to work with it. You'll probably
struggle to get it to work with LinuxCNC.
Is the motor brushed or brushless? Brushed motors generally have two
main power wires, brushless normally have 3.
Graham Dunn Inc.
> 630 Henry Street
> Dalton, Ohio 44618
> Phone: (330)828-2105ext. 2031
>
> -Original Message-
> From: Todd Zuercher
> Sent: Thursday, September 19, 2019 8:32 AM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] ADC - realti
: Thursday, September 19, 2019 8:32 AM
To: Enhanced Machine Controller (EMC)
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
On Thursday 19 September 2019 09:39:41 Curtis Dutton wrote:
> I appreciate the help and information.
>
> One last question before I go out and try this. I found a servo motor
> with a serial encoder. What interface board should I use to read that
> if I were using an 8i20 to power the servo?
>
It is not too unusual to use the torsion in a rotating shaft as a load
indicator. Sensors at both ends aligned at zero force. The app I saw was
using this on the turbine shaft for a 125 Mw generator. Just a comment. ;-)
On 9/18/19 5:30 PM, Chris Albertson wrote:
One way to measure force is
I appreciate the help and information.
One last question before I go out and try this. I found a servo motor with
a serial encoder. What interface board should I use to read that if I were
using an 8i20 to power the servo?
On Thu, Sep 19, 2019 at 9:06 AM Les Newell
wrote:
> If you are trying
If you are trying to counterbalance a pure weight this system would
inevitably end up accelerating into it's travel limits. However if the
load has some sort of spring component it should be stable. For instance
if you are trying to counterbalance a load so the force feedback is
providing most
To: Enhanced Machine Controller (EMC)
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
Thanks for correcting me on that.
Thaddeus Waldner
Newdale School
Elkton, SD 57026
From: andy pugh
Sent: Thursday, September 19, 2019 4:03 AM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] ADC - realtime for load cell
On Thu, 19 Sep 2019 at 02
On Thu, 19 Sep 2019 at 02:14, Thaddeus Waldner wrote:
> Standard strain gages have a usable resolution of about 6000, as far as I
> know.
>
You can do much better than that. I used to use home-made clip-gauges when
I worked in the structural integrity field. Those were just a bent bit of
clock
What will be the total travel of this ballscrew?
Is it static or does it travel as well?
On Thu, 19 Sep 2019 at 01:39, Curtis Dutton 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
The OP said he needs a 1KHz sample rate. Those chips are about 50x to
slow. Doing both high resolution and high bandwidth will be a hard
problem.
On Wed, Sep 18, 2019 at 6:01 PM Nathan Hartman
wrote:
> On Wed, Sep 18, 2019 at 9:38 AM Curtis Dutton wrote:
>
> > On Tue, Sep 17, 2019 at
Standard strain gages have a usable resolution of about 6000, as far as I know.
> On Sep 18, 2019, at 7:58 PM, Nathan Hartman wrote:
>
> On Wed, Sep 18, 2019 at 9:38 AM Curtis Dutton wrote:
>
>> On Tue, Sep 17, 2019 at 6:17 PM Chris Albertson >>
>> wrote:
>>
>>> If you want better than
On Wed, Sep 18, 2019 at 9:38 AM Curtis Dutton wrote:
> On Tue, Sep 17, 2019 at 6:17 PM Chris Albertson >
> 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
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
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
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 wrote:
> Chris thanks for the info.
>
> I'm not exactly certain at this point what
On 9/18/2019 11:15 AM, Jon Elson wrote:
On Tue, Sep 17, 2019 at 6:17 PM Chris Albertson
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.
I've never heard of anybody getting 16-bit
MAX11905 might do the job. 20 bit. but spendy. probably $50 in singles.
QSPI and SPI for interfaces. data rate 1600 ksps. SAR > 16 bit gets
really touchy... CMRR, noise, etc. Good luck.
On 9/18/19 7:01 AM, Curtis Dutton wrote:
Right now my test set up is going to consist of a 6i25, 7i85 and
On Tue, Sep 17, 2019 at 6:17 PM Chris Albertson
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.
I've never heard of anybody getting 16-bit resolution from a
load cell or strain gauge.
Right now my test set up is going to consist of a 6i25, 7i85 and an 8i20. I
wonder if the 7i85 could expose a BSPI interface. Or could I tack a BSPI on
to the 6i25's spare 25 pin connector?
I also am considering just writing a parallel port driver running at some
higher rate than the servo thread
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
wrote:
> If you
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
On Tue, 17 Sep 2019 at 22:41, andy pugh wrote:
This .comp file shows how to control/decode data gathered by the Mesa BSPI
> driver:
>
> https://github.com/LinuxCNC/linuxcnc/blob/master/src/hal/drivers/mesa_7i65.comp
>
(Note that the Mesa 7i65 also has analog-digital conversion, but again only
On Tue, 17 Sep 2019 at 22:26, Curtis Dutton wrote:
>
> 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.
The obvious answer is probably:
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
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