Control Algorithm

The TCS control algorithm has two independent control algorithms, drive moment control (AMR) and brake moment control (BMR). TCS evaluated the filtered wheel speed signal from ABS speed processing to recognizes when a wheel is going to start slipping. As soon as wheel(s) spin was detected, BMR will intervene automatically in the brake system to increase traction and AMR intervenes in the engine function to reduce engine torque and keep vehicle stable via connected to ECM by CAN data bus.

The BMR increases the pressure actively in the brakes either to generate a brake differential effect by means of pressure increase in one wheel on split-mu situation or on homogeneous mu, to reduce quickly the wheel spin and stabilize the car by increase pressure in both rear wheels simultaneously. In order to compensate the clearance of the brake, BMR control starts with a filling pulse.

The following control algorithm is on the basis of comparison between slip threshold and control deviation (RA), the slip difference of driven wheel. The slip threshold is calculated depends on the vehicle speed, acceleration, driving condition such as driving straight or in the curve, split mu or homogeneous mu road surface. Pressure modulation will be applied by pressure increase or decrease pulse to satisfy the different control condition that dependence of control deviations, wheel acceleration and driving condition.

The AMR controls the engine torque by means of spark retard and ignition cut off. The control concept and the calculation of slip threshold of AMR is similar to that BMR. However, the threshold values of AMR and BMR are different, but tuned to each other. Whenever the wheel slip is higher than the slip threshold value then AMR calculated the optimal engine torque reduce value and transmitted it via CAN bus to the EMS. Then EMS will response to reduce engine torque accordingly by spark retard and/or ignition cutoff. AMR will request EMS to increase torque as long as the wheel slip value is lower than slip threshold.