Hey, Looking for something else this turned up and I thought I'd share. It's on their 7 post test rig (1 at each corner + x/y/z on the sprung part I believe). And before anyone whines about the flexi nose I'm pretty sure this is a few years old and all we're seeing is "standard" flex..... If you're really geeky pause it towards the end and have a look at some of the figures on the 'puter screen. It's hi-res btw, enjoy! Cheers, Ian [ame=http://www.youtube.com/watch?v=_SPflUyT1rQ]Red Bull's Seven Post Shaker Rig (1080p) - YouTube[/ame]
Really cool find. Imagine that it must have been a demonstration run or something as they didn't have the engine et. al in. There were a couple of times that the drivers (assuming dummy) head got tossed around pretty hard. Do they program a series of events from actual race data, either track surface info, or crash data to simluate and determine structural strength from this or is it for something else?
Would seem like they are testing extreme movements/instances to measure how the chassis holds up as well as to understand the forces placed upon the driver.
By the looks of all that shaking around, they are setting the car up for when FA pushes Seb wide at the curva grande!
Figured you guys may enjoy that. I *think* (no more than WAG's!) they've got everything "significant" there. A dummy engine block, the g/box casing, tub itself etc. Note the weights mounted at the front to, presumably, duplicate the weight of all the "missing" bits. I'd assume the same thing in the "empty" pods - Worst case scenario as it were. [I presume the missing sub-assemblies (radiators, ECU's etc) are all tested (more violently yet!) on stand-alone on vibration tables somewhere else.] This rig is designed to place forces into the car and record the forces that the car puts back into the rig. No neck muscles in dummy's! But, I agree, it does look remarkably violent at times! Again, my 02c; The parameters they use are normally what's come back from the track. Indeed. My first thought was "why are they testing the thing off road!?" Another WAG is they may "increase" certain parameters by, I dunno, 20-30% to see if anything fails. But I guess we just don't see the car this way often; Bouncing over kerbs, loading up at Eau Rouge etc at the speeds they're doing does put some very high loads into the thing - Just we don't get to see it this way often. For example, there's never more than a few inches (kerb height?) of movement from the wheel posts. It may be a "worst case" lap that they're using but I'm sure it's not just jiggling around at random! Cheers, Ian
Dunno where this guy's getting these from, but if you click on his name his "channel" comes up with all kinds of cool stuff, all posted fairly recently. Here's another. I won't post 'em all as now you know where to look you're on yer own! Cheers, Ian [ame=http://www.youtube.com/watch?v=GsIcl1dsDIU]Red Bull preparing its model for wind-tunnel testing - YouTube[/ame]
Awesome. As to the excitation signals: The amplitudes are far too large for real-world track data. At the screen at the end, you can see amplitude/mean input boxes for the actuators, yet the actuator movement clearly isn't sinusoidal, and has varying frequency as well as amplitudes. I'd say they're not doing stress tests, but system identification runs with APRB signals.
Hmmm. Interesting. You may very well be correct (of course ) Questions/comments; - APRB? [A quick Google sent me down some blind alleys on that one!] - I'm not so sure the amplitudes are *that* big. I've now watched it a few times and reckon the most the wheel posts ever move is ~150mm and generally less - ie, pretty standard kerb height. Then the other side does the same - Analogous to jumping from kerb to kerb across the track? [Monaco comes to mind?] It's definitely "pushing the limits", and as I said maybe they've upped the amplitude (and decreased periods?) some to see if anything fails? - Why should the actuator movements be sinusoidal? I doubt very much that's what happens in the real world, but would love to be proved wrong...... - Same Q for amplitude - Some kerbs are bigger than others after all. My WAG is they've taken some "worst case" data they collected from many different tracks and merged it into a "horrible lap" for testing on the rig? Fascinating stuff anyway, Cheers, Ian
Sorry, too much specialised lingo here - my general thought is that they don't do load tests in that video, but try to identify the suspension's/car's behaviour. Of course you know much about every single part, but often superposition of single behaviours doesn't yield a satisfying description of the whole system. We do stuff like that quite often (acutally, my boss is one of the leading scientists in terms of system identification) - place something on some sort of test facility, hit it with special exitation signals, measure the output signals, create a mathematical model. "APRBS" means Amplitude modulated pseudo random binary signal, just think of it as signal in form of a series of steps up and down with varying step heights. For reasons too boring to elaborate on, it is often the best kind of signal to use for identification purposes, as it excites a wide frequency spectrum in a short timespan compared to ie sinus sweeps. Then again it might very well be that they're doing load tests, maybe with overscaled amplitudes. The view of a car on a rig with seemingly random movements just hit home here As I said - may very well be In their program, they can enter mean and amplitude of the actuator movements, thus you'd expect that they have some sort of signal that has these properties
OK, gotcha. Thx. It's certainly a complex system to model. I read somewhere that frequencies <~50hz can be pretty much ignored as they're pretty much handled by the tires. Easy-peasy, right! APBRS found it!...... Fair comment..... Cheers, Ian
You did, Sir. You did. (The parts that didn't go right over my head were actually quite interesting...)
I'd rather guess frequencies larger than 50Hz - typo? Anyway, depends on the tires and how precise you wand everything to be.. Depends on how often you do it and how well your gut feeling about what to do is developed The interesting thing is that the methodology is essentially the same for everything, doesn't matter if you want to identify the behaviour of a F1 car's suspension or the way a building heats up or the parameters of an electric motor. I was wondering if I should write "APRBS signal" in my first post, but that would then have been "amplitude modulated pseudo random binary signal signal"!
How about checking to see who's paying attention?! You are of course absolutely correct, again! Got my < & >'s ass about face. No doubt. IIRC, it was a story about Hendricks taxicab shaker rig, so I guess 'not very' would suffice.... Where I suspect 'gut feel' equates to a doctorate or two & many years experience...... APRBS was the successful search.... Never thought to try 'APRB signal' Cheers, Ian
