Geek Speak

The per­for­mance ben­e­fits of elec­tronic sta­bil­ity con­trol

Motor (Australia) - - CONTENTS - JAMES WHITBOURN

ELEC­TRONIC sta­bil­ity con­trol (ESC) is the now well-known name given to the safety fo­cussed col­lec­tion of sen­sors, ac­tu­a­tors and elec­tronic con­trol unit found in most cars of the last five years.

Stud­ies have shown that ESC could pre­vent a third of fa­tal crashes – clearly, it’s a pow­er­ful safety ally, which is why it’s been manda­tory in new cars sold in Aus­tralia since Novem­ber 2013.

But be­yond its core safety role, the pow­er­ful high-per­for­mance po­ten­tial of elec­tronic sta­bil­ity con­trol has be­come starkly ob­vi­ous to the world’s car mak­ers. When you have sen­sors that can mea­sure han­dling be­hav­iour and ac­tu­a­tors that can, to some de­gree, con­trol the chas­sis, the pos­si­bil­i­ties of a hi-po han­dling sys­tem are too tan­ta­lis­ing for any chas­sis en­gi­neer to re­sist. Sen­sors in an ESCe­quipped car al­ready mon­i­tor the steer­ing an­gle, throt­tle po­si­tion, the speed of in­di­vid­ual wheels, chas­sis roll and yaw (the car’s ro­ta­tion about the ver­ti­cal axis), as well as the lat­eral and lon­gi­tu­di­nal ac­cel­er­a­tion of the car.

Mean­while, by-wire throt­tles and brake ac­tu­a­tors, which use the vacuum brake booster and ad­di­tional hy­draulic pumps to in­di­vid­u­ally squeeze discs be­tween calipers, al­low the ESC ECU to take sen­sor in­puts that are in­ter­preted as an out-of-con­trol car and pro­vide speedy, selec­tive brak­ing and throt­tle in­ter­ven­tion to bring it all back into line.

This ESC hard­ware is stan­dard from cheap hatch­backs up and hi-po mod­els in­vari­ably take ad­van­tage, of­fer­ing any­thing from a sporty ESC cal­i­bra­tion or switch­able in­ter­ven­tion thresh­old, to a full torque vec­tor­ing sys­tem.

Forth­com­ing mega-Mercs, such as the AMG GT R, will fea­ture a nine-step ad­justable trac­tion con­trol sys­tem which, work­ing in con­cert with an elec­tronic LSD, will let the driver pick pre­cisely how much rear tyre slip he or she wants.

This dif­fers from the ESC-based limited-slip diff func­tions found from the VW Golf GTI and BMW M135i to the McLaren P1, which ap­ply brak­ing at the slip-prone wheel to di­vert torque to the other.

Even our home-grown HSV GTS uses ESC hard­ware and soft­ware to de­liver a torque vec­tor­ing sys­tem that brakes the in­side rear wheel to di­vert torque to the outer one. This cre­ates a ‘ro­ta­tional mo­ment’ that helps quell un­der­steer, mean­ing press­ing the loud pedal can now gen­er­ate a high-tech point­ing of the nose (an al­ter­na­tive to the old­school power over­steer method, with the ESC switched off).

"The pos­si­bil­i­ties are too tan­ta­lis­ing for any chas­sis en­gi­neer to re­sist"

The new Mazda G-Vec­tor­ing Con­trol sys­tem takes a dif­fer­ent ap­proach. The GVC sys­tem slightly cuts en­gine power in a frac­tion of a se­cond dur­ing turn in, mim­ick­ing the trail brak­ing tech­nique of an ex­pert driver to de­liver en­hanced steer­ing com­mu­ni­ca­tion, pre­ci­sion and in­volve­ment.

It seems that the days of rou­tinely de­ac­ti­vat­ing your hi-po car’s ESC may soon be gone (and not just be­cause many mod­ern cars won’t let you). For a quick – or good – time, it’ll in­stead be es­sen­tial to en­sure it’s switched on.

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