ABS Control Cycle Curves

ABS CONTROL CYCLE CURVES
As the brake pedal is depressed, brake fluid pressure increases correspondingly, which in turn decreases wheel speed. When brake fluid pressure reaches point "A" (where wheel deceleration exceeds "- b0"), the control module transmits a "hold" signal to hold the brake fluid pressure in wheel cylinder at that point. At the same time, the control module computes a "dummy" vehicle speed. When the wheel speed drops below the slip ratio setting (= speed less than the dummy vehicle speed based on the predetermined value) at point "B" of the brake fluid pressure, the control module then transmits a "decrease" signal to prevent wheel lock-up. This causes the brake fluid pressure to decrease.

After brake fluid pressure is decreased, wheel acceleration increases. When it exceeds the wheel acceleration setting "+ b10" at point "C" (brake fluid pressure), the control module transmits a "hold" signal to hold the brake fluid pressure at that point. When wheel acceleration setting value "+ b20" is exceeded and when brake fluid pressure is at point "D", the control module judges that wheel lock-up will not occur and then transmits an "increase" signal to increase brake fluid pressure.

When wheel acceleration drops below "+ b20" at point "E" (which occurred due to a brake fluid pressure increase), the repetition of the "hold" and "increase" signals takes place a at constant cycle.

When wheel deceleration exceeds "- b0", at point "F" of the brake fluid pressure, the control module immediately transmits a "decrease" signal to decrease brake fluid pressure.