Method And Code For Determining Characteristic Of Road Surface Beneath Moving Vehicle
First Claim
1. A method for characterizing a road surface encountered by a driven wheel of a vehicle, wherein the vehicle includes a torque converter providing a fluid couple between an input shaft driven by an engine and an output shaft coupled to the driven wheel, the method comprising:
- determining a first measure based on a first value representative of a current rotational speed of the input shaft and a second value representative of a current rotational speed of the output shaft;
determining a second measure based on successive values for the first measure, the second measure being representative of a rate of change of the first measure over time;
generating a set of successive values for the second measure; and
identifying the characteristic based on the set.
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Accused Products
Abstract
In a method for characterizing a road surface beneath a moving vehicle whose powertrain includes a torque converter coupling the engine to a driven wheel, a set of successive values for the torque converter'"'"'s slip error rate is generated using filtered values for engine speed and torque converter turbine speed. The road surface characteristic is identified based on the set of slip error rate values, as through a comparison of the set with a plurality of case statements, wherein each case statement corresponds with a different road characteristic and/or general surface type. Weighted average values are calculated based on subsets of the values within the set, for use in identifying transitions from one type of surface to another, or one surface characteristic to another. Indicated slip error rates generated in response to changes in an engine torque demand request are also identified to avoid a false indication.
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Citations
19 Claims
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1. A method for characterizing a road surface encountered by a driven wheel of a vehicle, wherein the vehicle includes a torque converter providing a fluid couple between an input shaft driven by an engine and an output shaft coupled to the driven wheel, the method comprising:
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determining a first measure based on a first value representative of a current rotational speed of the input shaft and a second value representative of a current rotational speed of the output shaft; determining a second measure based on successive values for the first measure, the second measure being representative of a rate of change of the first measure over time; generating a set of successive values for the second measure; and identifying the characteristic based on the set. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for determining a characteristic of a road surface beneath moving vehicle, wherein the vehicle is propelled by a powertrain that includes an engine responsive to a demand signal, and a torque converter having an impeller coupled to the engine and a turbine coupled to a driven wheel, the method comprising:
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determining a measure based on a pair of first values representative of a current and a prior rotational speed of the torque converter impeller, and on a pair of second values representative of a prior and a current rotational speed of the torque converter turbine; generating a set of a plurality of values for the measure; and identifying the characteristic based on the set. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A computer-readable storage medium including computer-executable code for characterizing a road surface encountered by a driven wheel of a vehicle, wherein the vehicle includes a torque converter providing a fluid couple between an input shaft driven by an engine and an output shaft coupled to the driven wheel, the engine generating an output responsive to a torque demand request, the storage medium including:
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code for determining a first measure based on a first value representative of a current rotational speed of the input shaft and a second value representative of a current rotational speed of the output shaft; code for determining a second measure based on successive values for the first measure, the second measure being representative of a rate of change of the first measure over time; code for generating a set of successive values for the second measure; and code for identifying the characteristic based on the set. - View Dependent Claims (16, 17, 18, 19)
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Specification