Wheel sensor
AssigneeMelexis Technologies SA
InventorOleksandr Zhuk
Life of this patent
Estimating the term…
Abstract
A method of measuring and transmitting a tire characteristic using a sensor device mounted to a tire of a wheel, the sensor device comprising a sensor element, an accelerometer, a wireless transmitter, and a microprocessor; the method comprising the steps of: a) obtaining acceleration data; b) digitally filtering the acceleration data; c) determining moments in time when the wheel is in an angular position range; d) obtaining other sensor data; e) transmitting the other sensor data at said moments in time, step b) comprising using exponential moving average filters connected in series, corresponding to a predefined set of formulas comprising parameters, and f) determining number of samples per 360° rotation, and setting the parameters to a value proportional to said number of samples. A sensor device adapted for performing said method.
Claims16
A method of measuring and transmitting a tire characteristic using a sensor device mounted or mountable to a tire of a wheel of a vehicle, the sensor device comprising:
- at least one sensor element for sensing a characteristic of the tire, an accelerometer, a wireless transmitter or transceiver, and a controller;
- the method comprising the steps of:
- a) obtaining information from an acceleration sensor at a sampling frequency and digitizing said information, thereby obtaining acceleration data;
- b) digitally filtering the acceleration data to reduce noise;
- c) determining at least two moments in time at which the wheel is in a constant angular position range;
- d) obtaining and digitizing sensor information from at least one other sensor adapted for measuring a characteristic of the tire, thereby obtaining other sensor data;
- e) transmitting the other sensor data to a receiver at said moments in time;
- wherein:
- step b) comprises making use of a plurality of at least two digital filters connected in series, each of the at least two digital filters being an exponential moving average filter having a filter characteristic corresponding to a set of predefined formulas comprising one or more parameters;
- and
- step c) comprises:
- selecting said moments in time as the moments at which an output of one of the EMA-filters crosses an output of another EMA filter, or
- selecting said moments in time as the moments at which the output of one of the EMA-filters crosses zero, or crosses a value equal to zero plus a predefined constant offset, the offset being a value in the range from −0.4 g to +0.4 g, or
- selecting said moments in time as the moments at which the output of one of the EMA-filters crosses an average value or crosses a value equal to said average value plus the predefined constant offset, the offset being a value in the range from −0.4 g to +0.4 g;
- and wherein the method further comprises step f) of determining the number of samples between said moments in time, and setting each of said parameters to a value proportional to said number of samples.
A method of measuring and transmitting a tire characteristic using a sensor device mounted or mountable to a tire of a wheel of a vehicle, the sensor device comprising:
- at least one sensor element for sensing a characteristic of the tire, an accelerometer, a wireless transmitter or transceiver, and a controller;
- the method comprising the steps of:
- a) obtaining information from an acceleration sensor at a sampling frequency and digitizing said information, thereby obtaining acceleration data;
- b) digitally filtering the acceleration data to reduce noise;
- c) determining at least two moments in time at which the wheel is in a constant angular position range;
- d) obtaining and digitizing sensor information from at least one other sensor adapted for measuring a characteristic of the tire, thereby obtaining other sensor data;
- e) transmitting the other sensor data to a receiver at said moments in time;
- wherein:
- step b) comprises making use of a plurality of at least two digital filters connected in series, each of the at least two digital filters being an exponential moving average filter having a filter characteristic corresponding to a set of predefined formulas comprising one or more parameters;
- wherein the predefined set of formulas comprising the one or more parameters is the following set of formulas, or an equivalent set of formulas, the formula for the first EMA-filter being:
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- wherein xi, is a sample of the digitized acceleration data,
- EMA[1]i, is the “i”-th value of the first Exponential Moving Average block,
- “i” is an index which is incremented by one for each additional data sample,
- N1 is a floating point number,
- and the formula for the second EMA-filter being:
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- wherein N2 is a floating point number;
- wherein the method further comprises step f) of determining the number of samples between said moments in time, and setting each of said parameters to a value proportional to said number of samples;
- and
- wherein the parameters N1, N2 are chosen proportional to said number of samples between the two moments in time at which the wheel is in constant angular position range.
Dependencies are inferred from the claim text.