is the Dynomotion controll as confusing as it seems?

**Gunmachinist** · 10-29-2020, 08:06 PM

How this looking?

**TomKerekes** · 10-30-2020, 10:14 PM

Still saturating the output.

**Gunmachinist** · 10-31-2020, 08:10 AM

Ok, so do you have a suggestion on what perameter I can change? Is the feed forward correct?

**TomKerekes** · 10-31-2020, 09:33 AM

If you are in a VW bug following your friend in a Tesla and you have to keep pegging the gas to the floor, what should you tell your friend to do?

**Gunmachinist** · 10-31-2020, 01:59 PM

Slow down. I don't know if I need to slow the output or acceleration. If I slow acceleration It slows too much.

**TomKerekes** · 10-31-2020, 03:34 PM

Drive slower is Correct. If you can't keep up you need to tell your friend to either not go as fast and/or not to accelerate as hard.

Correct we want the Output to stay away from the max, but you don't have direct control over the Output. Imagine following your friend, he still driving fast, and you decide not to push the gas all the way down. That will just make things worse. Rather you must tell him to drive slower so you don't have to to ever push the gas all the way down. The only other option is to get a faster car.

The idea is to tell your friend to drive in such a way so that you can always easily keep up without having to floor it (saturation).

There are 3 things you are allowed to tell your friend how to drive:

#1 - never go faster than this (Velocity)
#2 - never push the gas more than this (Acceleration)
#3 - never move the gas/brake pedal faster than this (Jerk)

The move you are testing is entirely Jerk limited so Velocity and Acceleration limits never come into play. They would if you moved farther.

This is like telling your friend it is ok to go 1000mph and use full Tesla acceleration and I will follow you in my VW Bug and nearly keep up. But haha the catch is he is only allowed to push the accelerator down very gradually. So gradually that it should take say one full minute to push the accelerator all the way down. Furthermore you tell him to drive forward only 100 feet and stop. So he gradually pushes the accelerator down to maybe 5% down, gets up to like10MPH, by that time it is already time to consider stopping (gradually reducing the accelerator and gradually applying the brakes) to stop at the 100 ft mark. Can you see his limits on Velocity and Acceleration were of no consideration? But if you told him to drive 1000 miles they would be?

Our Version 4.35d has an instructional program (TripsWPF.exe) almost like a game where you can vary parameters and see the resulting motion instantly. You might play with it to help get an understanding.

Here I entered your parameters:

is the Dynomotion controll as confusing as it seems?-gun-jpg

The initial conditions are zero because we are starting from a stop. Jerk is set to your 100000. The Accel and Decel are both set to your 80000. And Vel Max to your 205000. And the Distance to your 35000 count move size.

Note the Distance (blue) moves 35000 as requested.

Note the Accel (red) gradually ramps up toward your 80000 limit. At your specified ramp rate (Jerk=100000) it would take 0.8 seconds to reach 80000. But after 0.56 seconds we must begin to stop. The acceleration is about 56000. So any Acceleration Limits above 56000 will make no difference.

Note the max Velocity (green) is 31000 counts/sec. Way below your limit of 205000. And occurs at 1.1 seconds where the acceleration has ramped back to zero and begins to go negative to start slowing down.

You will need to have a clear understanding of these relationships to be able to tune your system. So basically you might tell your friend its ok to move the accelerator faster, but don't push it more than so far down, and also never go faster than some reasonable speed and I'll be able to keep up with you no matter how short or long the distance.

HTH

**Gunmachinist** · 10-31-2020, 05:42 PM

Thank you, that helps a bunch I'll look at the new program and see if I can get a better outcome.

**Gunmachinist** · 11-01-2020, 05:31 PM

I did some re-tuning with the assistance of TripsWPF and I believe my servos may be acting better but I cannot seem to get the output to form a straight line (if it's supposed to). here is a few current screen shots.