Mesa 7i77 and linear encoder tuning PID.

Cheers Andy .... its been more work than I ever imaged.
Every corner you turn seems to be 10 times more difficult than you possibly imagined.
This should now be the enjoyable bit, now most of the mechanical hard work is done, getting the machine setup and the making all the nice tactile bits for the control etc.

Do you and your 8i20 s fancy a little holiday in Norfolk then?

It’s been worrying me that if I change the drives, what to ... how much.... will that cure the problem....

I haven’t had a chance to get the motor encoder cable made up yet, that’s on the cards for tonight.
So I’ll report back findings from there.

As I said before, this is all virgin territory for me, so please bear with me as I’m still pretty clueless.
That said, for me, my gut instinct from the first time i starting doing battle, was the drives may be the problem.
“You might end up with two PID loops in HAL, one running the drive/motor under encoder feedback, and a second one (probably slow and I-only) tweaking that one from the linear scale feedback.”

Is that available as a “cut and paste”

This may be a stupid suggestion, but what would happen if:
setp hm2_5i25.0.encoder.00.scale 25600... (25600 linear encoder)
setp hm2_5i25.0.encoder.05.scale 8192 ... (8192 output from drive)
then

net x-pos-fb <= hm2_5i25.0.encoder.00.position
net x-vel-fb <= hm2_5i25.0.encoder.05.velocity

or something along those lines ?

I composing an email to Omron, to see if they can shed any light ......

Probably not, though it shouldn't be any more difficult than a single PID really.

if .... you know what your'e doing!

Further developments...


Encoder output from drive / motor connected to 7i77 as encoder 2 for vel / pos feedback

Linear encoder left connected as encoder 0

I’ve also changed the belt and added more tension by this point.
Looks like some of the delay is before the motor / drive responds and the rest mechanical?

Motor off in e-stop – wrench tuning ball screw mild acceleration – red motor encoder – blue linear encoder

Motor off in e-stop – wrench tuning ball screw mild acceleration – red motor encoder – blue linear encoder

zoom1

Motor off in e-stop – wrench tuning ball screw mild acceleration – red motor encoder – blue linear encoder

zomm 2

Motor off in e-stop – wrench tuning ball screw harsh acceleration – red motor encoder – blue linear encoder