Pedal:throttle butterfly map

[zac510]

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.

[hardingfv32]

I believe that each throttle map must mimic some form of mechanical system and it's actions controlled by the driver through pedal input.

Does anyone see where this might conflict with some of the off throttle strategies?

Brian

[zac510]

Mimicking a mechanical system suggests an open loop but of course opening the throttle to 50% by the ECU when the pedal is at 0% is not mimicking a mechanical system!

I guess it must be open loop. Any closed loop input like vehicle speed would immediately make it open for a traction control use or accusation.

[hardingfv32]

There should be no reason that the engine throttle could not be open to the 50% level when the throttle pedal is at 0%. This could be done with some form of complicated cam following mechanical system. I would think the throttle system has a more conventional motion ratio when the pedal comes of 0% (full up).

In any case, the ECU bases its settings from the engine throttle position.

Brian

[747heavy]

........................ not the rigth place - sorry

[hardingfv32]

I was going to challenge your statement as it applies to F1 engines but thought I should check the rules first. I do not see any reference to the throttle system having to mimic a mechanical system in the current rules. It would seem everything you stated could apply to the current F1 engine control systems.

Brian

[zac510]

We're getting into the realm of liberal interpretation of the regulation here too.

Thanks 747heavy for your input! By the current rules it certainly would do that, particularly for the rear brake bias management.

The thought for this thread came up after hearing somebody complain about computers meddling with the driver's skill. But I thought if it's an open loop system, repeatable and consistent, then there is no computer meddling at all.

[hardingfv32]

Rear brake bias management..... I could see where the ECU would not get any info pertaining to wheel speed. If data is available it would be monitored by the FIA. The sensors and harness are all approved by the FIA, so not much room for creativity.

I would not say there is any room for liberal interpretation of these regulations.

Brian

[Edis]

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.