| DTC strategy |
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- Inoperative Yaw Rate & Lateral G sensor
- Open or short of Yaw Rate & Lateral G sensor
- Inoperative HECU
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| Case 1 |
Monitoring Period |
- Continuous (during stable driving)
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| Enable Conditions |
- By building a reference lateral G from the yaw-rate sensor, wheel speed sensor and the SAS it is possible to test the later G Signal on plausibility. If during stable vehicle behavior an lateral G Failure larger than approximately 2.5 m/s2 occurs, the ESC controller will disregard the lateral G sensor information so that a false ESC intervention is prevented. A fault is recognized after 1.6 s during model validity.
- The measured and offset compensated yaw rate signal is compared to the reference yaw rate signal calculated from yaw rate sensor, lateral G sensor, SAS and wheel speed sensor. If the measured yaw rate deviates more than 2.5 °/s plus a dynamic threshold from the reference yaw rate during model validity, a failure is recognized after 1.6 s. The dynamic threshold is between 2.5°/s and more than 5°/s. A typical value is 3°/s.
- During the possibility to observe the recognition time depends on the amount of failure.
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| Case 2 |
Monitoring Period |
- Continuous (during driving)
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| Enable Conditions |
- During normal driving conditions the long time filtered driving direction is straight ahead. The long time filtered later G value is equivalent to the offset. If the offset value exceeds a threshold of approximately 2.25 m/s2
an later G fault is determined. Failure detection time depends on the driving distance, vehicle speed and on the amount of failed later G signal. Within 30 km of symmetrical driving the calculated offset corresponds to the sensor offset.
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| Case 3 |
Monitoring Period |
- Continuous (If no under voltage is detected)
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| Enable Conditions |
- A fault is detected If the lateral G is higher than 15 m/s2
for more than 800 ms.
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| Case 4 |
Monitoring Period |
- Continuous (during standstill)
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| Enable Conditions |
- If the filtered value of |lateral G| is larger than 7 m/s2
for more than 400 m/s a fault is set.
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| Case 5 |
Monitoring Period |
- Continuous (dependent on driving situation)
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| Enable Conditions |
- Standstill compensation:
- The offset corresponds to the measured and filtered input value. Failure threshold 5.25°/s.
- Fast compensation (during driving if no standstill compensation could be completed):
- The offset corresponds to the slightly filtered deviation between measured yaw rate and the reference yaw rate calculated from SAS, lateral G sensor and wheel speed sensor. Failure threshold is 7.5 °/s.
- Long-term ("normal") compensation (during driving after successful standstill or fast offset compensation):
- The offset corresponds to the strong filtered deviation between measured yaw rate and the reference yaw rate calculated from SAS, lateral G sensor and wheel speed sensor. Failure threshold is 7.5 °/s
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| Case 6 |
Monitoring Period |
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| Enable Conditions |
- The measured yaw rate and the model yaw rates, calculated from the wheel speed sensor and SAS are compared. If the signals doesn.t fit and forward driving is recognized, a fault is determined.
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| Case 7 |
Monitoring Period |
- Continuous (after initialization of the YRS and if no under voltage is detected)
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| Enable Conditions |
- The yaw rate sensor BITE logic evaluates the BITE-signal by extraction of the measured yaw rate of the vehicle. The allowed range for the BITE-signal is 25 °/s ± 7 °/s. If the BITE-signal is not in the allowed range, a suspected failure bit is set after 200 ms. A failure is set within 400 ms.
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| Case 8 |
Monitoring Period |
- After YRS-initialization, no under voltage
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| Enable Conditions |
- Depending on the driving conditions a signal gradient higher than 10 ~ 23 °/s / 40 ms sets a suspected failure bit after 280 ms, unless a single signal peak is recognized by a peakfilter. A failure is set, if the good check is not settled successfully after 10 s.
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| Case 9 |
Monitoring Period |
- Continuous (except spinning, use of handbrake, unsteady driving conditions or a detected under voltage)
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| Enable Conditions |
- During standstill
- The allowed range of the yaw rate sensor signal is ±30 °s. Leaving this range for 5 s sets a fault. In case of driving off after the failure was present for longer than 500 ms during standstill, the fault is detected immediately.
- While driving
- The allowed range of the yaw rate sensor signal is ±94.75 °s and a suspected failure bit is set, if the signal is out of this range for 500 ms. A fault is set after 1 s.
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| Fail Safe |
- Reduced controller function.
- Inhibit the ESC control and ABS/EBD control is available.
- The ESC warning lamps are activated.
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