Apparatus and method for determining a state parameter of an object to be monitored

• US 20050246142A1
• Filed: 03/04/2005
• Published: 11/03/2005
• Est. Priority Date: 03/04/2004
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Hammerschmidt, Dirk
• Granted Patent: US 7,310,593 B2
• Time in Patent Office: Days
• US Class Current: 702/189
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
• CPC Class Codes: B60C 23/0474 Measurement control, e.g. setting measurement rate or calibrating of sensors; Further processing of measured values, e.g. filtering, compensating or slope monitoring

Abstract

An apparatus for determining a state parameter of an object to be monitored comprises a means for providing a plurality of measurement values, wherein the measurement values comprise information relating to the state parameter of the object to be monitored, a comparison means for comparing the measurement value to a predeterminable comparison parameter, wherein the comparison means is formed to output a first comparison signal when a predeterminable number of measurement values falls below the comparison parameter within a measurement interval, or to output a second comparison signal when the predeterminable number of measurement values exceeds or reaches the comparison parameter, wherein the first comparison signal or the second comparison signal indicate the state parameter.

Claims

1. An apparatus for determining a state parameter of an object to be monitored, comprising:

a provider for providing a plurality of measurement values, wherein the measurement values comprise information relating to the state parameter of the object to be monitored;

a comparator for comparing the measurement values with a predeterminable comparison parameter, wherein the comparator is formed to output a first comparison signal when a predeterminable number of measurement values within a measurement interval falls below the comparison parameter, or to output a second comparison signal when the predeterminable number of measurement values reaches or exceeds the comparison parameter, wherein the first comparison signal or the second comparison signal indicate the state parameter.

2. The apparatus according to claim 1, wherein the state parameter is a driving situation of a vehicle, wherein the driving situation comprises a non-operated state and a driving state, wherein the provider for providing the plurality of measurement values comprises a tire pressure sensor or an acceleration sensor.

3. The apparatus according to claim 1, wherein the provider or providing the measurement values comprises an evaluator for evaluating the plurality of measurement values to provide evaluated measurement values as measurement values.

4. The apparatus according to claim 3, wherein the evaluator comprises a determiner for determining an average value of the plurality of measurement values and a subtracter for determining a difference between the measurement values and the average value, wherein the evaluated measurement values are the difference or an amount of the difference.

5. The apparatus according to claim 4, wherein the determiner for determining the average value comprises a low-pass filter to determine the average value by low-pass filtering.

6. The apparatus according to claim 3, wherein the evaluator comprises a subtracter for determining a difference between subsequent measurement values, wherein the evaluation measurement values are the difference or an amount of the difference.

7. The apparatus according to claim 3, wherein the evaluator has a squarer, which is formed to square the difference or an amount of the difference to obtain a squared difference, wherein the evaluated measurement values are the squared difference.

8. The apparatus according to claim 1, further comprising a determiner for determining the predeterminable comparison parameter, wherein the determiner is formed to provide the predeterminable comparison parameter.

9. The apparatus according to claim 1, wherein the determiner for determining the predeterminable comparison parameter is formed to determine an average value of the measurement values, wherein the average value of the evaluated measurement values according to claims 3 to 7 is the predeterminable comparison parameter.

10. The apparatus according to claim 9, wherein the determiner for determining the predeterminable comparison parameter has low-pass filters to determine the average value of the measurement values by low-pass filtering.

11. The apparatus according to claim 8, wherein the determiner for determining the comparison parameter is formed to output a multiple of the comparison parameter of a fraction of the comparison parameter as the predeterminable comparison parameter.

12. The apparatus according to claim 8, wherein the determiner for determining the predeterminable comparison parameter is controllable, and wherein the apparatus for determining the state parameter comprises a controller for controlling the determiner for determining the predeterminable comparison parameter, wherein the controller is formed to generate a first control signal, in response to which the determiner for determining the predeterminable comparison parameter determines the predeterminable comparison parameter, and to generate a second control signal, in response to which the determiner for determining the predeterminable comparison parameter interrupts a determination of the predeterminable comparison parameter.

13. The apparatus according to claim 12, wherein the state parameter is a driving situation of a vehicle, wherein the driving situation comprises a non-operated state and a driving state, wherein the control circuit is formed to output the first control signal when the first or the second control signal indicates the control state and to output the second control signal when the first or second control signal indicates the driving state, wherein the controller is formed to derive the first control signal or the second control signal from the first comparison signal or the second comparison signal.

14. The apparatus according to claim 1, wherein the provider for providing the plurality of measurement values comprises a measurement sensor, wherein the measurement sensor is a tire pressure sensor or an acceleration sensor, wherein the state parameter is a driving situation of a vehicle, wherein the driving situation comprises a non-operated state and a driving state, wherein the measurement sensor has a first measurement rate in the non-operated state and a second measurement rate in the driving state, wherein the first measurement rate and the second measurement rate are different.

15. The apparatus according to claim 1, wherein the state parameter is a driving situation of a vehicle, wherein the driving situation comprises a non-operated state and a driving state, wherein the apparatus for determining the state parameter comprises a provider for providing the predeterminable comparison parameter, wherein the provider for providing is formed to maintain the predeterminable comparison parameter at its current value when the first or the second comparison signal indicate a change from the non-operated state to the driving state, wherein the provider for providing is formed to continue the determination of the predeterminable comparison parameter when the first of the second comparison signal indicate the change from the driving state to the non-operated state.

16. The apparatus according to claim 1, wherein the measurement interval is determined by a number of measurement values.

17. The apparatus according to claim 16, wherein the number of measurement values is set.

18. The apparatus according to claim 17, further comprising a determiner for determining the number of measurement values.

19. The apparatus according to claim 18, wherein the determiner for determining the number of measurement values is formed to determine the number of measurement values by using a maximum allowable error probability, wherein the maximum allowable error probability indicates a maximum allowable probability of a wrong decision about the first or the second comparison signal from a plurality of comparisons.

20. The apparatus according to claim 18, wherein the determiner for determining the number of measurement values is formed to determine the number of measurement values from a ratio of logarithms of an error probability of a measurement value and the maximum allowable error probability.

21. The apparatus according to claim 1, further comprising a determiner for determining the predeterminable number.

22. The apparatus according to claim 21, wherein the determiner for determining the predeterminable number is formed to determine the predeterminable number in dependence on a standard deviation of the measurement values.

23. The apparatus according to claim 22, wherein the predeterminable number comprises a first predeterminable number and a second predeterminable number, wherein the determiner for determining the predeterminable number is formed to determine the first predeterminable number in dependence on a first standard deviation of the measurement values and to determine the second predeterminable number in dependence on a second standard deviation, wherein a first weighting point is associated to the first standard deviation and wherein a second weighting point is associated to the second standard deviation, wherein the comparator is formed to perform a plurality of comparisons, wherein the first or second weighting point is associated to every comparison, and to generate the first or the second comparison signal based on a sum of the weighting points.

24. The apparatus according to claim 1, wherein the state parameter is a driving situation of a vehicle, wherein the driving situation comprises a non-operated state and a driving state, wherein the first comparison parameter indicates the non-operated state and wherein the second comparison parameter indicates the driving state.

25. The apparatus according to claims 1, which is formed such that a transition is made from a non-operated state to a driving state when a predetermined number of exceedings of a current difference square over a predetermined multiple of a short-term average value of the difference squares occurs within a predetermined number of measurements.

26. The apparatus according to claim 1, wherein a transition is made from a driving state to a non-operated state when the switching condition from the non-operated state to the driving state is not fulfilled within a predetermined number of measurements.

27. The apparatus according to claim 1, which is formed such that the multiple of the short-term average value is limited by a maximum value, to ensure that high pressure deviations, which are not plausible in the non-operated state, always lead to a transition to the driving state.

28. The apparatus according to claim 1, which is formed such that a multiple of a short-term average value is limited by a minimum value to ensure that pressure deviations, which are clearly too low for a driving state, cannot lead to an unnecessary transition to the driving state.

29. The apparatus according to claim 1, which is formed such that a frozen value of a short-term average value of the difference squares is adapted to the proportionality of the thermal noise, which should cause the main portion of the measurement differences in the non-operated state, to the absolute temperature by a temperature compensation, so that in a temperature increase the switching threshold, which defines the transition from the non-operated state to the driving state is also raised in order to make the switching condition independent of the temperature.

30. The apparatus according to claim 19, which is formed such that the decision is always repeated when a decision criterion is fulfilled, wherein for the case that the decision is not the same in the repetition, the decision is discarded and the repetitions are terminated, and for the case that the decision is the same in the repetition, the repetition is repeated until n repetitions with the same results are present and only then the decision is finally made, wherein the error probability for the n-fold decision is p_{e(n of n)}=p_e1ⁿ.

31. The apparatus according to claim 30, which is formed such that repetitions are only made when due to a single decision attempt a decision has been made, when this attempt already shows that probably no decision will be made so that the repetitions can be omitted and the energy consumption-intensive further measurements can be saved.

32. The apparatus according to claim 30, herein the decision is a transition from the parking state to the driving state.

33. The apparatus according to claim 30, which is formed such that not all repetitions have to be the same for the decision to be made but that a rate is defined that m of n decision attempts have to be positive, wherein the error probability is

p_{d(m of n)}=p_e1ⁿ/(1−

p_e1)^m-n.

34. The apparatus according to claim 1, which is formed such that several thresholds are defined which have to occur with a different frequency to lead to the decision.

35. The apparatus according to claim 34, wherein a first threshold has to occur 10 times in a 3-fold standard deviation, and wherein a second threshold has to occur 5 times in a 4-fold standard deviation, and wherein a third threshold has to occur twice in a 5-fold standard deviation, wherein the decision is only finally made when one of the criteria associated to the different thresholds is fulfilled within a defined time window.

36. The apparatus according to claim 35, which is formed such that points are associated to every threshold.

37. The apparatus according to claim 36, wherein a first threshold provides a point in 3-fold standard deviation, wherein a second threshold provides two points in 4-fold standard deviation, wherein a third threshold provides four points in 5-fold standard deviation, wherein the points are summed over a defined time window and the decision is only made when a defined minimum number of points is achieved.

38. The apparatus according to claim 1, which is formed such that the time intervals of the repetition measurements do not have to be within the same period as the measurements prior to the threshold exceeding but can take place faster in order to ensure a sampling rate, which lies, on the one hand, still significantly below the bandwidth of the superposed noise but, on the other hand, oversamples the signal to be detected, which can indicate pressure changes caused by driving, wherein a sampling rate is larger than the Nyquist rate defined by the Shannon sampling theorem, wherein when the repetition criteria is not fulfilled, a switch-back to the old sampling rate defined for the parking state is made, and wherein, when the repetition criterion is fulfilled, the increased sampling rate is maintained or a change to another sampling rate defined for the driving state is made.

39. A method for determining a state parameter of an object to be monitored, comprising the steps of:

providing a plurality of measurement values, wherein the measurement values comprise information relating to the state parameter of the object to be monitored;

comparing the measurement values to a predeterminable comparison parameter to generate and output a first comparison signal when a predeterminable number of measurement values within a measurement interval falls below the comparison parameter or to generate and output a second comparison signal when the predeterminable number of measurement values reaches or exceeds the comparison parameter, wherein the first comparison signal or the second comparison signal indicate the state parameter.

40. A computer program with a program code for performing the method for determining a state parameter of an object to be monitored, comprising the steps of:

providing a plurality of measurement values, wherein the measurement values comprise information relating to the state parameter of the object to be monitored;

comparing the measurement values to a predeterminable comparison parameter to generate and output a first comparison signal when a predeterminable number of measurement values within a measurement interval falls below the comparison parameter or to generate and output a second comparison signal when the predeterminable number of measurement values reaches or exceeds the comparison parameter, wherein the first comparison signal or the second comparison signal indicate the state parameter,

when the computer program runs on a computer.