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Also, although I've not yet fully worked out the kinematics in my head, I think the DSE four link is on the right track by introducing a rotational degree of freedom on roughly the roll axis. I'd bet that the DSE setup is very free in roll.
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Not sure what you are referring to? The bushing design? If so, this is not the solution to the constraint problem with a four link (parallel/semi-parallel). The issue is that one upper link needs to get a bit longer, or the other to get a bit shorter in roll in order to create a bind free system. Their bushing design is rotationally "free," at least statically (not sure how it will work when it is loaded in the actually suspension with a thrust load applied to the swivel thing they patented?), but this isn't where the binding issue comes into play. Think of it this way, a rod end has the same rotational freedom as their (unloaded) bushing, though it clearly can't rotate 360 degrees: it still has enough to accomodate the amount of roll angle induced by the axle in practical terms. If you agree, and look at the system with this in mind, you'll see what I am getting at. Again, the reason their system will work in roll is due to the compliance (radial, in this case) of the bushings used.
As far as the side view kinematics and rules, you are completely correct, the four link setup has no disadvantage, nor advantage over a three link, the same rules apply. Here again, the geometry of the system in side view is VERY important in determining the behavior of the vehicle, and it gets even more interesting when you look at how it behaves dynamically, it's not enough to say that the roll center height, IC, etc are "this" by design, one needs to consider the migration aspects of the system in practice to see how the car will behave in real life.
And regarding the AME stuff, the suspension engineer on my team happens to have a few years of direct experience with that setup.
Mark