Method for self-calibrating an accelerometer mounted on a wheel of a vehicle while said vehicle is moving
First Claim
1. A method for self-calibrating, while a vehicle is moving, an accelerometer (Ax) having a plane of maximum sensitivity (X) and designed to supply a signal representative of gravity, mounted on a wheel (R) of the vehicle so that its plane of maximum sensitivity (X) is secant with the axis of rotation of the wheel (R), said method being characterized in that, for an established speed of the vehicle:
- on the one hand the average value and on the other hand the amplitude of the signal representative of the acceleration Acc-read delivered by the accelerometer are calculated by a computer processor, based on measurements performed by means of the accelerometer (Ax) during a time window (f) corresponding to the time needed for the wheel (R) to complete n rotations, with n>
1,and the values of a gain C1 and of an offset C2 of the accelerometer (Ax) are determined by the computer processor resolving the system of two equations with two unknown values;
ω
2r=C1×
(average value of Acc-read)+C2
2 g=C1×
(amplitude of Acc-read)with;
ω
the speed of rotation of the wheel,r the radius of the wheel (R), andg the value of the Earth'"'"'s gravity.
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Accused Products
Abstract
A method for self-calibrating, while a vehicle is moving, an accelerometer mounted on a wheel of the vehicle so that its plane of maximum sensitivity is secant with the axis of rotation of the wheel. The average value and on the other hand the amplitude of the signal representative of the acceleration Acc-read delivered by the accelerometer are calculated first, for an established speed of the vehicle, based on measurements performed by the accelerometer during a time window corresponding to the time needed for the wheel to complete n rotations, with n>1, then the values of the gain C1 and of the offset C2 of the accelerometer are determined by resolving the system of two equations with two unknown values:
ω2R=C1×(average value of Acc-read)+C2
2 g=C1×(amplitude of Acc-read)
- with:
- ω the speed of rotation of the wheel,
- R the radius of the wheel.
8 Citations
7 Claims
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1. A method for self-calibrating, while a vehicle is moving, an accelerometer (Ax) having a plane of maximum sensitivity (X) and designed to supply a signal representative of gravity, mounted on a wheel (R) of the vehicle so that its plane of maximum sensitivity (X) is secant with the axis of rotation of the wheel (R), said method being characterized in that, for an established speed of the vehicle:
-
on the one hand the average value and on the other hand the amplitude of the signal representative of the acceleration Acc-read delivered by the accelerometer are calculated by a computer processor, based on measurements performed by means of the accelerometer (Ax) during a time window (f) corresponding to the time needed for the wheel (R) to complete n rotations, with n>
1,and the values of a gain C1 and of an offset C2 of the accelerometer (Ax) are determined by the computer processor resolving the system of two equations with two unknown values;
ω
2r=C1×
(average value of Acc-read)+C2
2 g=C1×
(amplitude of Acc-read)with; ω
the speed of rotation of the wheel,r the radius of the wheel (R), and g the value of the Earth'"'"'s gravity. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification