Viscous Damper Manufacturers

Thanks; this looks like just the kind of thing I need.

Lucky...I usually have to implement what I design. Especially when I volunteer an idea and the project leader says, "Why don't you make one of those for us..."

There are some rubber like, electrometric?, units that are use for building trailers. Also Barrymount is a name brand that you can investigate.

Gunner

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.

Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner

If it is a sharp resonance at a frequency that does not change, you might consider adding a leaf type spring with a weight on it tuned to that frequency. The energy will transfer to the spring and weight and be disipated there.

Dan

I only get excused from the work if it's a mechanical change, and the designer and I still have to work together to get something practical that still embodies what I was asking for. Software changes I just do, and electrical changes only get taken out of my hands after I've blocked out the circuit & shown that it'll work, but before I can really claim credit.

What's almost worse is that I have gained a reputation for coming up with offbeat, but workable solutions to difficult problems. Since I'm also a smartass this means that every once in a while I'll make an absurd suggestion trying for a few yuks only to have someone with clout look inspired and say "heyyy, that may be the solution -- Tim, why don't you work out the math..."

Noooooo

A short piece of multi-strand steel cable can serve well as a spring. There's a lot of internal friction there. It's sometimes used on high-tension transmission lines and tower stays.

Jerry

That's an interesting thought, I may plug that into my model and see if it'll work. I have some very nice solutions that involve dampers, but they may not interest the folks who actually have to make the changes.

The only drawback I see to your resonant damping idea is the fact that it'll need to be tuned if the natural frequency of the system changes -- my customer is building something to work with _other_ customer's equipment; while we can guarantee that any installation of this type will resonate we can't be certain of the exact frequency until the customer finishes his equipment & hangs it on.

Consider removing the resonant frequencies from your command trajectory:

Good idea but it's not an option here -- the resonance is not only in the control loop but it's right around the gain crossover frequency. Simply notching it out means reducing loop bandwidth by a factor of 10 or so, and there's external disturbances that mean I need that bandwidth. I can mirror the resonance and anti-resonance with a lossy notch and a lossy resonance in closed-loop, but then I have to worry about tuning for different customers.

Killing the resonance looks _very_ attractive.