Coming to this thread late, but after reading the preceding technical discussions of various sources of car vibrations and wobble, described as "twisting", "shaking", "Chubby Checkering", "nibbling" etc..., I could not help adding a comment here. That is, there exists an invention that has proven very useful in industrial control and aerospace applications, and, in my view, could be readily applied to build a highly effective car suspension.
So, what is it? Instead of writing a rehashed description, I will defer to an excellent narration of this in the following video.
Rockwell Retro Encabulator - YouTube
So, some might say that this is really a
means of propulsion, and ask what it has to do with
suspension systems.
Ah a fair question, but the attentive watcher will notice that at 1:15 the presenter said that
"...side fumbling was effectively prevented", and then again at 1:35, that
"...it may also be employed in conjunction with the drawn reciprocation dingle arm, to reduce sinusoidal depleneration." Clearly, a simple modification will take advantage of the device anti-vibration property to make an active suspension of a very high suppression bandwidth.
OK, then, why is it that we have not seen this method in use at all? Not being an automotive engineer, actually not even an ME but an EE, I will defer to the automotive experts present in this forum, but of course have pondered this question myself.
The only potential drawbacks I could come up with are 1) the higher cost relative to the current century-old spring-based suspension, and 2) that the superior performance of the encabulating suspension may become a liability. Imagine a driver going down the highway with some loose or missing wheel lugs. He would be totally oblivious to the impending disaster, if his car had such an effective suspension, up to the point the loose wheel separated itself from the axle!
Still, with the proliferation of hybrid and electric vehicle, in the future can we expect to see cars with encabulating integrated suspension/propulsion systems? The advent of eletronics means that a car maker can let the active suspension system cancel out the road vibration for a smooth ride, while various onboard sensors will keep an eye on the deteriorating parts, in order to warn the driver of any hazardous situation that might develop.
PS. Having no skin in the game (I am not affiliated with any effort to design or manufacture any device using the discussed technology), I only brought this up for our enlightened members, in the remote chance that they were not already aware of it.
PPS. Laymen who are turned off by the technical discussion in the video will be well served by a Wikipedia article, which describes this important invention in plain English. You will find it
here, which says that this was invented way back in 1944.