Closing Control Loops

"We'll refer it to a lawyer" comes up in other contexts.

Jerry

--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

Hey, I'm 3 for 3. I heartily recommend doing the writing before the kids come along, or after they leave home. In the intervening

20+ years, content yourself with smaller projects and keep up with the tree planting!

Mark Borgerson

I'm in the middle of "let's put a faster computer in there" to solve all the sensor noise and control response problems. The magic words seem to be "Extended Kalman Filter". ;-)

Mark Borgerson

From Chapter 1, "The Basics":

"A final 'problem' in this list is that control systems are not magic. Real systems have real limitations, and nothing ? not even an automatic control system ? can overcome the laws of physics. Limitations in the strength of your actuators, in the response speed of every part of the system, in your plant's tendency to allow itself to be driven nicely, and in your sensor's ability to deliver noise-free measurements will all limit the ultimate performance of your system."

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google?  See http://cfaj.freeshell.org/google/

--snip--

War stories would be nice -- particularly of battles won as well as lost.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google?  See http://cfaj.freeshell.org/google/

I had the reverse situation occur once. I was going to fly with an instructor one night at an airport where the runway lights were out of service for construction work. The instructor said he'd put a pot at the end of the runway so we could find it to land. I was puzzled as to how a /part/ (allowing for the instructor's heavy New England accent) was going to help us find the runway. As we taxied out to depart, I saw the pot and realized that when he'd said "pot", he meant "pot"!

And there's the time the Texan was telling me how much he hated "all-filled" capacitors. [Show me a capacitor that isn't filled with something.]

Oh, please! Do Tell!

Please don't be a tease! ;-P

Thanks! Rich

--
Elect Me President in 2008! I will:
A. Fire the IRS, and abolish the income tax
B. Legalize drugs
C. Stand down all military actions by the US that don\'t involve actual
   military aggression against US territory
D. Declare World Peace I.

how about a draw?

we recently had a blowup in one of our videoscreens. we use telecomms

48Vdc power supplies, and the one in the burn-in rack failed - the feedback network went open-circuit, it was in the airflow path and not conformally coated, and managed to corrode. Boom, up goes the voltage; it was a 25kW supply. Fortunately they put in a supervisory loop, which shut the power supply down. Unfortunately, it took 10ms to do so.

Fortunately I had designed in some kick-ass transient clamping and fusing (nearby lightning strike protection), which protected the circuitry. Unfortunately the over-voltage was such as to limit the current to a value which didnt immediately blow the fuse, and 10ms = eternity as far as junction thermal time constants go, so the TVSs all suicided, thereby snotting the fuses. best not to think about the 16 screws that need to be removed to repair each one....

Fortunately the problem happened in our factory, so the costs associated with removing/dismantling/remantling/replacing all of the modules was minimal. I am now working on a monster clamp, so the same problem doesnt take out a customers $2,000,000 screen :)

Cheers Terry

I bet that'd get those shunt-regulating, class-A'ing audiophools drooling.

Tim

-- Deep Fryer: a very philosophical monk. Website:

Reminds me of a cartoon on a Tshirt web site that has a blackboard and a professeur wanting more detail on step two, bearing in mind the three steps of maths on the backboard are:-

1. Complicated maths
2. "By a bit of magic we get to"
3. Less complicated maths

I do not have the URL to hand at present.

--
Paul Carpenter          | paul@pcserviceselectronics.co.uk
    PC Services
              GNU H8 & mailing list info
             For those web sites you hate

yep. best I wire it with monster cables....

Cheers Terry

Vaguely reminds me of The Underpants Gnomes, on South Park. They would sneak into your room while you're sleeping, and steal your underpants. Their motivation, it was revealed, was Profit. The kids caught the Underpants Gnomes stealing Tweek's underpants, and followed them to the Underpants Gnome cavern. They had a chart much like that:

1. Steal Underpants.
3. Profit.

And when anybody asked what step 2 was, they just stood there and looked confused. And after a beat or two, "But, step 3 is Profit!" "Hooray!"

Guess you had to be there. :-/

Thanks, Rich

--
Elect Me President in 2008! I will:
A. Fire the IRS, and abolish the income tax
B. Legalize drugs
C. Stand down all military actions by the US that don\'t involve actual
   military aggression against US territory
D. Declare World Peace I.

Are any of the root locus solvers free? even really cheap? Not much use for one but if i go back to school i do not want have to repeat controls.

--
JosephKK
Gegen dummheit kampfen die Gotter Selbst, vergebens.  
--Schiller

...

I will look for my old Spirule. If I find it, you can borrow it. I'll post.

Jerry

--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

SciLab.

A free root locus solver. Also a free MatLab replacement/improvement. It's been characterized (here) as "about as friendly as a chain saw". Unfortunately I can't disagree. OTOH, if you want to draw a root locus it's as easy as:

H_s = %s / ((%s + 10) * (%s + 11)); // make a transfer function evans(H_s); // make a root locus of it

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google?  See http://cfaj.freeshell.org/google/

I will try scilab. I have DL'd it already.

--
JosephKK
Gegen dummheit kampfen die Gotter Selbst, vergebens.  
--Schiller