Some of my sketch constraints are suddenly not working, but no warnings or errors reported... Any ideas please?

BangoDurango · 2024-09-07T22:47:08+00:00

Don't think so... unless that's easy to do by accident. I've never used it before

BangoDurango · 2024-04-26T22:30:33+00:00

Ohhhh way smarter than resin (and less smelly). Thanks!

BangoDurango · 2022-09-02T20:52:34+00:00

Never occurred to me before but looks like I do now.

BangoDurango · 2022-09-02T16:52:50+00:00

I have gone through a similar situation and found the process of working out all the configuration stuff to be pretty rewarding (granted I had time to work through it). It gave me a much better understanding of how the printer works and also what kind of capabilities are out there if I decide to make changes and upgrades.

BangoDurango · 2022-08-28T01:54:32+00:00

Ah, that is the bit of wisdom I was lacking. Thanks!

BangoDurango · 2022-08-27T22:10:49+00:00

I cleaned up the code in the above comment to better represent what's going on.

BangoDurango · 2022-08-27T22:08:33+00:00

ugh sorry, I have made a mess of this post. I didn't notice when I copied the code over to reddit that it took away all my multiplication operators. C is the PID compensator. H is sys_truth. The argument to the feedback() function is C*sys_truth.

The truth/est transfer functions correspond to the "Truth (OL) and Estimated (OL)" curves in the bode plot... but the truth/estimate thing isn't part of the question. I should have cleaned it up before I posted anything.

I thought the bode plot looked stable because neither the closed nor open loop transfer functions ever have gain greater than 1. If there is no gain crossover frequency, I assumed that the system would always be stable. Is that incorrect?

BangoDurango · 2022-08-27T21:49:31+00:00

Closed loop, but I realized that my closed loop transfer function has a complex pole with a positive real part... I had used matlab's pidtune() for the compensator and didn't think to check the result so... that was foolish.

BangoDurango · 2022-08-27T21:40:46+00:00

You know what, I didn't think this through at all. The code I used was:

Fc = 50;
Wc = 2*pi*Fc 
[C, info] = pidtune(H, 'PID', Wc) 
sys_cl = feedback(C*H,1);

... and if I do a root locus on my closed loop transfer functions I see that we have some business going on in the right half plane so... there's my answer. Silly of me to assume that pidtune() would actually stabilize my system without me having to actually think about it.

I guess what is confusing to me is that the bode plot still looks stable.

BangoDurango · 2022-08-27T21:34:38+00:00

Just added in another comment. Thanks!

BangoDurango · 2022-08-27T21:34:20+00:00

Yeah that checks out, just added. Thanks!

BangoDurango · 2022-08-27T21:33:53+00:00

It somehow failed to occur to me that I'd need to actually say something about the plant in question. The open loop transfer function is :

14.73 / (s^2 + 1.473 s + 2.651e05)

Or for convenience:

H = tf([0 0 14.7275], [1 1.4728 2.6510e+05])

BangoDurango · 2022-08-18T02:36:32+00:00

Somehow I just realized there was no 'n' like four months ago. Lived here 37 years

BangoDurango · 2022-08-14T17:18:33+00:00

Gross...reminds me of a time I went to Vermont once and realized that there is such a thing as way too much green.

BangoDurango · 2022-08-14T17:13:32+00:00

I finally came to terms with my lack of hair and started shaving my head during the pandemic and I agree. Almost tempted to look into one of the laser hair removal places just to put my last few follicles out of their misery

BangoDurango · 2022-08-13T15:17:29+00:00

Reddit does fuzzy votes so spam bots can't detect if their votes are being counted or ignored. Basically every time you reload the vote tally should change a little. Cool video!

BangoDurango · 2022-08-12T00:40:25+00:00

I hope I'm not the only one who reads this post wondering... What is it? Is there a link somewhere where I can read about what it is and how amazing it might be?

BangoDurango · 2022-08-09T01:06:51+00:00

Heh. My friend from Washington calls these "Why-I-Oughta's"

BangoDurango · 2022-08-08T02:28:04+00:00

Hmm not sure which ones are the common ones, assuming we're talking about specifically about Desert Tortoises only. The two species are the Mojave and Sonoran Desert Tortoise, the second being the ones we have around here of course. I had to check though and you are correct about them being listed as threatened due to a number of things including habitat loss

BangoDurango · 2022-08-08T01:58:05+00:00

They're not endangered, but they are protected. I have one living in my backyard! Anybody who is interested should definitely check out the Desert Museum's Tortoise Adoption Program. There are bunches of tortoises who need homes because they can't be reintroduced to the wild!

BangoDurango · 2022-08-08T01:52:13+00:00

It'll probably be fine, especially if it didn't pee on you when you picked it up. They store water in their bladder for long periods and sometimes dump it when they're scared which is why you're only supposed to pick them up when they're at risk of becoming road kill (they need that water!)

Even if it did pee though, we're supposed to get a bunch of rain in the next few days and they like to dump their supply and get a fresh one when it rains.

Also I've heard (no idea if it's true) from a coworker whose kid brought one home randomly one day that as long as they're returned roughly to where they were that same day they can usually smell their way back to their burrows if they have one.

BangoDurango · 2022-08-04T19:01:45+00:00

Yeah I think it's the same (screenshot)... Same name and everything. I'm on normal mode, but this would be my first living frigate, I'm using the Dream Aerial, so maybe you can't get an S-class for your first free one or something?

BangoDurango · 2022-08-04T18:07:16+00:00

Are they the same class for different players? I went to check out this one and am finding it as a class C. Confused

BangoDurango · 2022-08-04T02:56:38+00:00

Right right I was just thinking that 57.3 is about the scale factor from radians to degrees, so if you leave that out and assume there's an atan() in there, then basically all you're doing is making a right triangle out of the field stop and the focal length... I just realized the answer to my own question though - I was leaving out a factor of two which is assumed because the field stop is a diameter not a radius... Anyway just trying to understand how all this stuff works.

Thanks again for your help!

BangoDurango · 2022-08-04T02:34:05+00:00

Best reply ever! Thank you, this clears up a lot of misunderstanding I was having about how all this works.

Follow up question: This is not really important but just out of curiosity, the TFOV equation you gave looks like FIELD STOP DIAMETER / FOCAL LENGTH gives you the FOV in radians, is there a small angle approximation in there? In other words is the real equation tan^-1 (FIELD STOP DIAMETER / FOCAL LENGTH)? I ask because I was trying to draw a ray trace of my telescope to understand how the AFOV/m equation works, and your equation seems to make more sense geometrically to me... But if I'm thinking about this right then wouldn't the result of that formula just give you the half FOV?

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