[willofgod]

I am prototyping an Arduino shield that can read up to 8 encoders. I plan on using it for an articulated arm, but I thought as long as I am doing one, I might as well make it for general use. I am not sure if there is any interest in such a thing here. If there is let me know.

[keebler303]

You can read 8 encoders at once? At what frequency? Do you have position counters? How big?

For wide application I'd say you need a minimum of 1 MHz count rate and a 32 bit position counter for each axis. I doubt that can be done on an arduino shield but I could be wrong. Then how are you going to get that data t the user? Your own application? How can it be used for another application? It sounds like it would be a pain to make it universal.

My $0.02
Matt

[willofgod]

Good questions. It operates at 16MHz (so a rotatory encoder with 50k counts can be read at ~4k RPM which should be plenty for most people) and the counter is programmable with a max of 32bits per axis. As the Arduino is serially getting counts from the shield via SPI, it is quite easy to utilize on board without any specialization. Obviously the amount of math performed on-board is limited by the power of the microprocessor, but getting joint angles, for instance, is well within its capabilities. This is far into prototype phase, it does certainly work.

[willofgod]

Oh, I see I missed answering your software question. Currently, in testing, I have a serial port reading the arduino's output of counts or joint angles. Things like feed speed, angles, etc are quick enough to do on the microprocessor. Any specialized kinematics would have to be on the PC.

[dtman2]

You should have a look at using linuxcnc together with the arduino. I managed to interface the UNO with a hal program with little effort - see for example LinuxCNC Support Forum :: Topic: Collecting data with Arduino and Python (1/4). If you use linuxcnc the kinematics will be relatively easy as there are many examples to work from.

[bones]

Hey Will, lol,
Yes I definatly be interested in it.
We are doing a simular project at work.
I'd be interested to hear how your going with it!

Rod

[willofgod]

Rod,

It is going extremely well. I will update here as major updates happen. If you want an email on it or anything shoot me a PM.