Join us in Chat. Click link in menu bar to join. Unofficial chat day is every Friday night (US time).
0 Members and 1 Guest are viewing this topic.
I have tried adjusting all the P,I,D ... and it doesn't seem to have ANY effect at all until you adjust them right down to the point where the unicycle feel's slow to respond and "mushy" but it still shudder's like mad. I've spent ages in the past trying to tune the PID and like I say noting seemed to change the shuddering. The shuddering just doesn't seem to get better or worse no matter what I do.
The schematic is based heavily on this instructable [...]
The motor controller I'm using is a Syren 25a and it's being controlled in simplified serial mode.
I cant post the code as it exceed's the 22000 characters limit. [...]
Ives not heard about connecting a capacitor across the motor but I imagine it would have to be a pretty beefy capacitor it's a 24v 500w motor. Anyone else know anything else about this ?
PID tuning may seem hard and like I said, you need to work in very small steps, especially if you really don't know what each does.Best way is to either 'scope the input-output relation, to see what really happens - does it overshoot, is it too slow etc.But check the serial first, as described below.
Did you try asking the guy who made it?
That may have something to do with the problem.Try changing the serial speed ("baud rate") to see if this changes the response in any way - if it do, you might need to use another mode.
Never mind, I have no intention of debugging an entire program (which from a quick look seems a bit messy) and the PID parameters can only be found with the exact combo of motor etc. that you have. Change the motor (or the ESC) and you'll have to change parameters all over.
Any DC motor should have a cap over its terminals. it's for quenching some of the noise it generates and it should have a cap from each terminal to the (grounded) motor housing.10nf..100nF ceramic caps is a good start.
Any advice on how ? .. I tried following the guide from wikipediahttp://en.wikipedia.org/wiki/PID_controllerabout a quarter way down the page under "manual tuning" ... it wont copy and paste properly.
But it jerk's no matter how low I set the Kp ...... Lowering the Kp further just seems to change the angle at which it jerks to correct itself . is that right?
How small adjustments? and where do I start/stop?
I set D to zero and commented I out completely .. I then increased P until I was getting definite oscillations I then backed that off to approx half and set about adjusting the D ...... until I ended up back where I started.
QuoteAny DC motor should have a cap over its terminals. it's for quenching some of the noise it generates and it should have a cap from each terminal to the (grounded) motor housing.10nf..100nF ceramic caps is a good start.Is it likely that this will have them built in?
if not just one cap from the + to the motor housing? what sort of size?
The derivative term slows the rate of change of the controller output
And I don't know how I missed your suggestion on the size of the cap's ... I can only apologise .. it was obvious when I re-read it . Can they by located at the ends of the motor wire (about 7" long) for the time being or do they need to be actually physically connected to the motor case and not just at the end of the wires? (which is the closest convenient mounting point).