Remora - ethernet NVEM / EC300 / EC500 cnc board

Sorry to the forum admins, I posted this in a separate thread because I wasn't sure whether to post my closed-loop question here, but my contributions to remora are directly related to this thread, so that's why this is a double post here.

It's been a while since I posted anything here, but it's never too late if you have the desire.
I've continued moving forward with my dual-head mitre saw project. I've developed a PwmGen module for Remora. At least it drives the motor, haha. Up to four modules could be instantiated, for which the four QDCs can also be used. I want this to develop a closed-loop system. Once again, I'm leaving the links to my GitHub in case anyone wants to take a look.
Scott, I know your time is short and tight, more or less like mine, haha. I've sent you a pull request on GitHub for this. When you can, take a look; everything can be improved.
I have a video of my tests online. I use a user interface I designed for a dual-head mitre saw. I welcome criticism. Although it's not very visible, I'll leave the link. It was only an open-loop test, but I was able to verify the PwmGen module works.
*****Now the questions********
I've read quite a bit about DC motor control here on the forum. For this case, I started using an old servo amplifier that the machine itself had as standard. This was controlled with a +/- 10V analog signal, which was quite a challenge to get working. The servo amplifier controlled a speed loop with a tachometer that the motor has, and the encoder is on the side of the moving head, that is, on the load, not on the motor. By the way, thanks to everyone who gave me instructions on the table cards; PCW, Tommylight, etc.

I want to skip the servo amplifier and use Remora with a simple H-bridge and the encoder. This is where I run into a problem. I need to use a PID loop in speed mode, but I don't have an encoder on the motor; I have it on the load. I'm not an expert in motor control loops, although I understand something, but I'm not sure if I can implement a closed loop with this configuration. Therefore, would it be mandatory to attach an encoder to the motor?

Greetings to all, thanks in advance.

rbobey1989 wrote:

I need to use a PID loop in speed mode, but I don't have an encoder on the motor; I have it on the load. I'm not an expert in motor control loops, although I understand something, but I'm not sure if I can implement a closed loop with this configuration. Therefore, would it be mandatory to attach an encoder to the motor?

It should work, needs some tuning and as little as possible of backlash between motor and encoder, so the answer to the last part is no, it is not mandatory, LinuxCNC does not care where the encoder is as long as they are physically attached (even with rope), and it can control DC servo motors with just a simple H-bridge.
I have done some simple drives that worked perfectly with LinuxCNC, leme see if i can find them:


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-Not very useful info bellow, feel free to skip.
And As general info, since audio amplifiers are getting really cheap, especially the D class ones, they can all be used as a servo drive, granted limited current capabilities and the only current limits built in are overload where it shuts completely down or no limiting and burns to a crisp!
There are plenty of use cases for them, but complicate things due to +-1V input sensitivity, that can be sometimes misused by bridging them and inverting one input, so only pwm should work. Some are bridged inside, so only inverting one input should do.

I did these commands but I'm getting the following error,
0010637 C Error: [__main__]

Hey Murphy, here is a small video of my lathe doing CSS. It appears to function as intended. I have included my halfile so you can compare

github.com/cakeslob/upload_things/blob/main/20180218_225707.mp4

Thanks Cakeslob, I'll have a look at this again in a couple of weeks as I'm away with work. 

    I did the whole process to change the firmware of the stlink, it was successful, but it does not appear on my PC, the only difference is that I did not find the blue stlink so I did it in a green one, I used two green stlinks, would there be any difference? If so, how do I find the blue stlink, when I go to buy the cover and everything is the same