Thoughts on designing a new controller

Hardware Electronics
80

Afterall, we don’t need the whole bar shipped, only templates that
register to the ends and provide mounting holes (at least if I understand
correctly…) to achieve this.

see New motor mount suggestion

this mount registers to the end, designed to fit unistrut or wood

Building on what @cmullins70 said, even without stratifying in to various
“small/medium/large” budget tiers, I’d be happy if there was a 3 or 5 item “if
you do X you’ll get Y benefit” that properly documented the “upgrade” or
change and talked about reasonable expected improvement in accuracy or
repeatability (or even reliability if applicable). There is a great sense of
urgency and engineering ingenuity in the air here, which is something I think
we all enjoy partaking in, but it does sometimes feel like we skip a cog every
now and then and the best we can do is point someone to a dense and rolling
400+ entry post that “kind of has the answer, you’ll get the idea…” but
doesn’t quite answer the question completely.

part of the problem we have is that some people are getting good accuracy,
others, are not, and we don’t know why.

My current working theory is that there are three main reasons for this

  1. frame (mostly top beam) is too flexible

  2. the calibration routine is not working well enough and is resulting in
    calculated measurements that are obviously wrong (I am thinking that holey
    triangulation will help this a lot, but I’m struggling to run it)

  3. the tape measure being used is inaccurate enough to cause grief. We recently
    had an interesting discussion on class 1, class 2, and unclassified tape
    measures. see
    In search of accurate measurements

we also don’t have anyone who has gotten a good accurate machine go through and
test other configs to see what effect the other configs have.

PS - Said a different way, I’m still hoping for a clear 1-2-3 for the what/why
of the new controller design.

We currently have three controllers

arduino mega and stock maslow controller
arduino due and modified maslow controller
arduino mega and TLE controller

Pairing one of these with a Raspberry Pi and using WebControl seems like it is a
huge win (I’ll say that being able to use my phone to bump things to get a
sprocket to 12 o’clock is a HUGE win compared to having to get to the computer
to move things and the machine to see if it’s in the right position yet)

So one goal of the new controller is to see if we can combine this, make the
controller run WebControl (or equivalent)

Additional features that we want to see if we can support (not in any order)

  1. support a stepper for a Z axis
  2. support other encoder types (SPI and RS422/RS485 communications)
  3. support 4 motor designs
  4. support higher current for the motors
  5. support higher voltages for the motors
  6. eliminate the ability to plug the power supply into the wrong plug
  7. current limiting on the motors to avoid frying chips
  8. current measurements on the motor drive
  9. wifi connectivity
  10. faster processor to handle the calculations a little better
  11. double precision floating point math for more accurate calculations

David Lang