Robbobnob wrote:9.3 Traction control :
No car may be equipped with a system or device which is capable of preventing the driven
wheels from spinning under power or of compensating for excessive throttle torque demand
by the driver.
8.2.1 All components of the engine, gearbox, clutch, differential and KERS in addition to all
associated actuators must be controlled by an Electronic Control Unit (ECU) which has been
manufactured by an FIA designated supplier to a specification determined by the FIA.
The ECU may only be used with FIA approved software and may only be connected to the
control system wiring loom, sensors and actuators in a manner specified by the FIA.
I think it's pretty clear cut, that even by modulating the torque output between KERS regeneration and the output shaft on the drive train would be considered traction control and would therefore be illegal.
Also any control of that system would have to be via the standardised ECU.
the ECU only generates demands, the response to those demands is mostly unmandated
eg the rules are satisfied with ECU demanding KERS motor activity states on/off ie equivalent to full excitation voltage or zero
this inherently gives falling torque with rpm, and helps against wheelspin, but does not prevent wheelspin ie make it impossible
presumably if the wheelspin is not stopped this is not compensation for excessive torque demand by the driver so the car is legal
(otherwise the cars are all illegal simply for mapping)
other more electrically efficient ways of KERS motoring could have different effects against wheelspin
varying the excitation voltage could give little or no fall in torque with rpm, this is in principle wheelspin-neutral or nearly so
this would be done by making current (equivalent to torque) the controlled variable
if the rate of change of excitation voltage is limited to less than the rate of change of motor back emf/rpm with wheelspin
the anti-wheelspin effect (the rate of fall of torque with rpm) will be usefully large
this ('slew rate limiting') is a normal facility in motor drives
better effects are possible using simple analogue networks eg with passive components, this again is an established facility
(to modify voltages when wheelspin causes rapid rpm/back emf changes)
the rules were intentionally written to allow anything that is not against the rules
particularly, they do not call for the KERS to be wheelspin-neutral
they allow KERS (and its 2014 big brother) to be anti-wheelspin (and anti-locking) but not fully so
they just call for it not to be a TC system as defined by the rules banning TC as defined by the rules banning TC as defined etc ...
IMO the rules say it's only TC if it stops wheelspin (entirely)
the above approach only resists wheelspin when there is wheelspin, ie there is no effect when spin has stopped, so it's legal
this potential will be greater in 2014, this has been recognised via the liberalisation of rear brake management and recovery