Method for processing information in a tire pressure monitoring system
First Claim
1. A method of measuring an undesired pressure drop in a tire of a vehicle and generating a warning signal responsive thereto, comprising the steps of:
- establishing a reference temperature;
determining at least one pressure warning threshold at the reference temperature;
measuring gauge pressure and gauge temperature within a tire cavity;
correcting the gauge pressure to a corrected pressure value at the reference temperature;
calculating from a series of corrected gauge pressure measurements a leak rate;
comparing the corrected pressure value at the calculated leak rate against the pressure warning threshold;
generating a warning signal based upon the comparison of the corrected pressure value at the calculated leak rate against the pressure warning threshold.
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Accused Products
Abstract
A method of processing information in a tire pressure monitoring system includes the steps of: establishing a reference temperature; determining a pressure warning threshold at the reference temperature; measuring gauge pressure and gauge temperature within a tire cavity; correcting the gauge pressure to a filtered pressure value at the reference temperature using the Ideal Gas Law; and comparing the filtered pressure value against the pressure warning threshold to determine the necessity for a warning signal. In an advanced form of the invention, the method includes determining a pressure leak rate; predicting the time interval that the filtered pressure value will cross the pressure warning threshold at the leak rate and generating progressive warnings to the driver over the time interval. Fuzzy logic is used to quantify the probability of a warning state for each data point, allow for measurement error; and report the state of maximum probability to minimize the occurrence of false warning. A warning utility function is derived based upon a combination of the filtered pressure and leak rate.
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Citations
19 Claims
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1. A method of measuring an undesired pressure drop in a tire of a vehicle and generating a warning signal responsive thereto, comprising the steps of:
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establishing a reference temperature;
determining at least one pressure warning threshold at the reference temperature;
measuring gauge pressure and gauge temperature within a tire cavity;
correcting the gauge pressure to a corrected pressure value at the reference temperature;
calculating from a series of corrected gauge pressure measurements a leak rate;
comparing the corrected pressure value at the calculated leak rate against the pressure warning threshold;
generating a warning signal based upon the comparison of the corrected pressure value at the calculated leak rate against the pressure warning threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of measuring an undesired pressure drop in a tire of a vehicle and generating a warning signal responsive thereto, comprising the steps of:
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establishing a reference temperature;
determining at least one pressure warning threshold at the reference temperature;
measuring gauge pressure and gauge temperature within a tire cavity;
correcting the gauge pressure to a filtered pressure value at the reference temperature;
comparing the filtered pressure value against the pressure warning threshold;
generating a warning signal upon an undesired pressure drop in the tire;
establishing a time left threshold on the value of anticipated time at which the filtered pressure value will cross the low pressure warning threshold;
determining whether the anticipated time is less than the threshold;
generating a warning signal when the anticipated time is less than the threshold;
developing data points from a series of successive measurements of pressure and temperature;
establishing a probability threshold value;
computing a time left probability based upon a plurality of recent said data points;
comparing the time left probability against the probability threshold value; and
generating a warning signal when the time left probability exceeds the probability threshold value.
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9. A method of measuring an undesired pressure drop in a tire of a vehicle and generating a warning signal responsive thereto, comprising the steps of:
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establishing a reference temperature;
determining at least one pressure warning threshold at the reference temperature;
measuring gauge pressure and gauge temperature within a tire cavity;
correcting the gauge pressure to a filtered pressure value at the reference temperature;
comparing the filtered pressure value against the pressure warning threshold;
generating a warning signal upon an undesired pressure drop in the tire;
developing data points from a series of successive measurements of gauge pressure and gauge temperature;
determining a pressure-temperature map based upon the data points and separated by boundaries defined by the Ideal Gas Law;
classifying each data point into a one of a plurality of states;
calculating state probabilities for each data point;
forming a vector of probabilities for each data point;
determining a current state vector representing an average of the vector of probabilities of each data point in the series of successive measurements;
identifying a state with a maximum probability; and
reporting the state of maximum probability. - View Dependent Claims (10)
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11. A method of identifying a leak rate in a tire of a vehicle, comprising the steps of:
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establishing a reference temperature;
taking a finite number of sample data points of gauge pressure and gauge temperature within a tire cavity;
compensating the measured pressure data into filtered pressure values at the reference temperature;
applying a recursive linear least squares regression filter to the pressure data to estimate a pressure leak rate.
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12. A method of identifying a leak rate in a tire of a vehicle, comprising the steps of:
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establishing a reference temperature;
taking a finite number of sample data points of gauge pressure and gauge temperature within a tire cavity;
compensating the measured pressure data into filtered pressure values at the reference temperature;
applying a recursive linear least squares regression filter to the pressure data to estimate a pressure leak rate and wherein the measured pressure data is compensated into filtered pressure values at the reference temperature utilizing the Ideal Gas Law. - View Dependent Claims (13, 14)
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15. A method of monitoring tire air pressure in a rolling vehicle, comprising:
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recording measured data pairs comprising values for pressure and temperature;
determining a characteristic curve for the measured data pairs;
determining filtered pressure values of the data pairs at a reference temperature utilizing the Ideal Gas Law;
comparing the filtered pressure values of the data pairs against at least one pressure threshold value; and
determining a zero intercept offset value corresponding to a measurement error factor.
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16. A method of monitoring tire air pressure in a rolling vehicle, comprising:
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recording measured data pairs comprising values for pressure and temperature;
determining a characteristic curve for the measured data pairs;
determining filtered pressure values of the data pairs at a reference temperature utilizing the Ideal Gas Law;
comparing the filtered pressure values of the data pairs against at least one pressure threshold value; and
determining a pressure leak rate based upon the measured data pairs. - View Dependent Claims (17)
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18. A method of monitoring tire air pressure in a rolling vehicle, comprising:
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recording measured data pairs comprising values for pressure and temperature;
determining a characteristic curve for the measured data pairs;
determining filtered pressure values of the data pairs at a reference temperature utilizing the Ideal Gas Law;
comparing the filtered pressure values of the data pairs against at least one pressure threshold value;
classifying each measured data pair into one of a plurality of states; and
calculating state probabilities for each measured data pair by means of a fuzzy logic. - View Dependent Claims (19)
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Specification