zac510 wrote:Does anybody know whether the pedal:throttle butterfly ratio in the SECU that allows the blown exhaust/valve cooling/etc is controlled by an open or closed loop circuit?
I suspect the former to avoid any chance of traction control.
There isn't any pedal-throttle ratio. I suspect that F1 use the typical torque demand approach that most cars with thottles under electronic control do.
Basically, the ECU uses the pedal position and engine speed to determine the torque requested by the driver. This torque request is the recalculated into an airmass request per combustion. The throttles are then operated so the engines get the correct airmass/combustion.
The throttles themselves are under closed loop control, there are two potentiometers that check the position of the throttles. One potentiometer is used to check the position, the second one is used to check the function of the first potentiometer in case of a failure. In most cars the throttles are operated by an electric motor, but in F1 a servovalve and a hydraulic actuator are used to operate them instead since it's lighter and faster but the principle is the same. The ECU tells the throttles to go to a certain position, the position is checked by the potentiometer and corrections are made until they are in the correct position. The ECU then checks the actual airmass/combustion and compare it with the requested airmass/combustion, it the actual value is lower or higher than the requested value corrections are made.
Traction control is a simple software function. If the driver for instance requests 300 Nm but the wheel speed sensors detect excessive slip a traction control function simply reduce the torque request, perhaps 250 Nm gives the ideal slip at just this particular moment.