CHASSIS - BRAKE
02HCH05Y
Slippery Surface
without TRAC Function
with TRAC Function
Engine and MG2
Motive Force Regulation
THS ECU
Skid Control ECU
Slippery
Surface
Brake
Actuator
Brake
the Slipping
Drive-wheel
CH-36
Outline of TRAC Function
If the driver presses the accelerator pedal aggressively when starting off or accelerating on a slippery
surface, the drive wheel could slip due to the excessive amount of torque that is generated. The
adjustment of the motive force and the control of the hydraulic brakes of the drive wheels accomplished
by THS II allow the TRAC function to help minimize the slippage of the drive wheels, and generate the
drive force that is appropriate for the road surface conditions.
For example, a comparison may be made between two vehicles, one with the TRAC function and the
other without. If the driver of each vehicle operates the accelerator pedal in a rough manner while driving
over a surface with different surface friction characteristics, the drive wheel on the slippery surface could
slip as illustrated. As a result, the vehicle could become unstable.
However, when the vehicle is equipped with the TRAC function, the skid control ECU instantly
determines the state of the vehicle and operates the brake actuator in order to apply the brake of the
slipping drive wheel. Simultaneously, the skid control ECU effects cooperative control with the THS
ECU, in order to adjust the motive force. Thus, this function can constantly maintain a stable vehicle
posture.
Driving condition on road with different surface friction characteristics