FYI: An Interesting Description of Syvecs Traction Control
05-08-2018, 08:14 PM
#1
FYI: An Interesting Description of Syvecs Traction Control
I'm still researching what I want to do with my Supra, and a lot Supra stuff now comes from a UK shop Garage Whifbiz. He's done some interesting stuff such as adapt a M3 DCT transmission. He also uses the Syvecs ECU. Syvecs if manufactured by Life and a more road car version of the L88. The folks at Life earlier made the Pectel ECUs which they sold to Cosworth and is used on many formula cars.
Anyway...I found the description from 2008 description of their traction control. The discussion includes multiple maps and EGT issues.
Anyway...I found the description from 2008 description of their traction control. The discussion includes multiple maps and EGT issues.
Re: Traction Control
Thu Jul 10, 2008 8:53 pm
The traction control strategy allows you to specify a spin target as a function of either steering wheel angle and road speed, or as a function of lateral G and road speed. Additionally if you have a lap beacon, you can tweak the spin target as a function of lap distance; if you already know that a track has a low grip section at a given point then you can adjust your spin targets for that section.
Spin is calculated by comparing individual wheel speeds to the road speed. A spin error is calculated by comparing the actual spin to the spin target, the result of this calculation multiplied by the gain, and that is used to generate a torque reduction value. This value is clamped as a function of RPM, before being used to index into the fuel cut severity and ignition retard lookup maps, that define the actual amount of fuel cut and actual ignition retard as a function of desired torque reduction and EGT.
You can use the EGT dimension to balance the torque reduction so as to prevent turbo or exhaust valve damage; imagine for a moment a situation with low EGT but too much wheelspin, you may be able to completely control the situation simply with ignition retard, it will be smoother (unless the resultant timing generates misfires) than using a fuel cut, but if the EGT was already high, the last thing you need is to dump even more heat into the exhaust, so a fuel cut would be better. Obviously if a situation starts with low EGTs but it's very slippy and the strategy has to run for a long time, you can configure the tables so that it "rides" up the EGT dimension with the bias shifting from retard to cut.
Hopefully this gives some insight into the way the traction control works,
Pat.
Thu Jul 10, 2008 8:53 pm
The traction control strategy allows you to specify a spin target as a function of either steering wheel angle and road speed, or as a function of lateral G and road speed. Additionally if you have a lap beacon, you can tweak the spin target as a function of lap distance; if you already know that a track has a low grip section at a given point then you can adjust your spin targets for that section.
Spin is calculated by comparing individual wheel speeds to the road speed. A spin error is calculated by comparing the actual spin to the spin target, the result of this calculation multiplied by the gain, and that is used to generate a torque reduction value. This value is clamped as a function of RPM, before being used to index into the fuel cut severity and ignition retard lookup maps, that define the actual amount of fuel cut and actual ignition retard as a function of desired torque reduction and EGT.
You can use the EGT dimension to balance the torque reduction so as to prevent turbo or exhaust valve damage; imagine for a moment a situation with low EGT but too much wheelspin, you may be able to completely control the situation simply with ignition retard, it will be smoother (unless the resultant timing generates misfires) than using a fuel cut, but if the EGT was already high, the last thing you need is to dump even more heat into the exhaust, so a fuel cut would be better. Obviously if a situation starts with low EGTs but it's very slippy and the strategy has to run for a long time, you can configure the tables so that it "rides" up the EGT dimension with the bias shifting from retard to cut.
Hopefully this gives some insight into the way the traction control works,
Pat.
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