This may seem like old news now but I figured I’d do this analysis anyway because it helps me understand these things, and hopefully it helps you too!
In 2014 the FIA allowed F1 teams to use a “powered control system” on the rear brake system as the additional regenerative capabilities of the MGU-K under the current regulations resulted in inconsistent retardation of the rear axle. Not that the teams had a choice as to whether they used such a system, as a conventional hydraulic setup would be incredibly inconsistent and – more importantly – unnatural to the driver. This system is more commonly known as brake-by-wire (BBW)
So what exactly happens when the driver hits the brake pedal?