Got this idea for a while now, came to me while watching the transmission/steering system on a battle tank during my military service (it is actually impressive how many things you could learn by watching around those things). It all came back to my mind while reading a diff-related topic and as it is unlikely for my team to build and use one, I thought of posting it here and get some discussion going.
The concept is really simple (and thats the beauty of it): It uses a simple, open diff (maybe from a small car/ATV, the lightest unit possible). On each side of the diff, there is an inboard brake rotor (on the diff output shaft or on each CV housing), each with a 2x2 (4 pot) caliper, like the ones AP Racing produces. Two pistons (out of four) on each caliper are actuated by the brake pedal, as in any normal 2pot caliper, while the other two are actuated by an electrovalve. The operation is such that the control system brakes the inner wheel both in corner entry (aiding turn-in) and each time the inner wheel spins excessively. The diff then sends more torque to the outer wheel (which has more traction). In extreme cases the system could even lock the inner wheel, acting somewhat like "tank-steering". On the plus side, the system sounds really simple and reliable(in case of system failure or malfunction, you just end up with an open diff) and no heavier than any diff setup, while having the ability of pseudo-torque vectoring (actually speed vectoring). On the downsides I can see overheating rear brakes and possibly lots of testing to make it actually work and make you faster. Any thoughts?