When the vehicle is turning with respect to a vertical axis the yaw rate sensor detects the yaw rate electroniclly by the vibration change of plate fork inside the yaw rate sensor. If yaw velocity reaches the specific velocity after it detects the vehicle’ yawing, the ESP control is reactivated. The later G sensor senses vehicle’s lateral G. A small element inside the sensor is attached to a deflectable leverarm by later G. Direction and magnitude of lateral G loaded to vehicle can be known with electrostatic capacity changing according to lateral G. The output voltage of the lateral G sensor is 2.5V when the vehicle is at a standstill. Only with lateral G sensor, the ESP can not be reactivated.
A lateral acceleration reference signal is calculated from the wheel speeds, the steering angle and the yaw rate signals to observe the lateral acceleration sensor signal. The difference between the reference signal and the sensor signal is evaluated for failure detection. A yaw rate reference signal is calculated from the wheel speeds, the steering angle and the lateral acceleration signals to observe the yaw rate sensor signal. The difference between the reference signal and the sensor signal, and the gradient of the measured sensor signal is evaluated for the failure detection. If the difference between estimated value and measured value of the sensor is larger than predefined value for predefined time, the failure is recognized.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Signal monitoring | ● Faulty Yaw Rate & Lateral G sensor ● Open or short of Yaw Rate & Lateral G sensor ● Faulty HECU |
Case1 | Detect Mode | ● Initial Check |
Enable Conditions | ● During standstill if lateral G value is larger than 7g, and continue 2sec. ● During standstill if yaw rate value is larger than 7deg/s, and continue 2sec. | |
Case2 | Detect Mode | ● Initial Check ● Outside the ABS control cycle ● Diagnosis mode |
Enable Conditions | ● If noise of input signal is happened 429times in 5sec , Which the amplitude of the sensor signal is larger than predefined value(standstill : 0.3g , driving:0.5g~ 1.0g). ● If noise of input signal is happened 429times in 5sec , Which the amplitude of the sensor signal is larger than predefined value(standstill : 8deg/s , driving:15deg/s~ 30deg/s). | |
Case3 | Detect Mode | ● Outside the ABS control cycle ● Inside the ABS control cycle ● Diagnosis mode |
Enable Conditions | ● When the difference between estimated value and measured value of the sensor is lager than 0.3 g, the difference value add and subtract. When sum Total value is larger than predefined value. ● When the difference between estimated value and measured value of the sensor is lager than 7deg/s, the difference value add and subtract. When sum Total value is larger than predefined value. | |
Case4 | Detect Mode | ● Outside the ABS control cycle ● Inside the ABS control cycle ● Diagnosis mode ● Failure mode |
Enable Conditions | ● When GND of yaw rate sensor and lateral G sensor are open. | |
Fail Safe | ● Inhibit the ESP control and allow the ABS/EBD/TCS control. Meanwhile, stop checking the ESP switch failure under the ESP control. ● The ESP warning lamps are activated. |
