GYROSCOPE STABILIZER FILTER
A method, a filtering module, and a computer-readable medium are configured to filter measurements acquired in a sensor reference system. Filtered measurements of motion sensors and a magnetometer attached to the device may then be used to determine orientation of a device in a non-inertial reference system. The measurements are filtered in a reference system, whose position relative to the sensor system can be calculated, and in which gravity and Earth's magnetic field have substantially constant direction and magnitude during the filtering window.
1 . A method for filtering a measurement acquired in a sensor reference system, the method comprising:
determining a transformation from a sensor reference system to a gyroscope reference system;
rotating at least one measurement from the sensor reference system to the gyroscope reference system using the transformation;
filtering the rotated at least one measurement; and
rotating the filtered at least one measurement back into the sensor reference system.
2 . The method of claim 1 , wherein the transformation is determined using a previous angular position of the gyroscope reference system in the sensor reference system, and an angular velocity measured in the sensor reference system.
3 . The method of claim 2 , wherein the angular velocity and the at least one measurement are acquired by sensors attached to a device, the sensor reference system being associated to a rigid body of the device.
4 . The method of claim 3 , wherein the method is performed by a data processing unit of the device.
5 . The method of claim 3 , wherein the angular velocity is measured by a 3D gyroscope.
6 . The method of claim 3 , wherein the device is a mobile communication device.
7 . The method of claim 1 , wherein the at least one measurement corresponds to an acceleration and/or to a magnetic field.
8 . The method of claim 7 , wherein the magnetic field is measured using a 3D magnetometer.
9 . The method of claim 7 , wherein the acceleration is measured using a 3D accelerometer.
10 . The method of claim 7 , wherein one of the at least one measurement corresponds to acceleration and the filtered at least one measurement is used to estimate a current linear position of the device.
11 . The method of claim 7 , further comprising:
applying a sensor fusion method to determine a current orientation of the sensor reference system relative to an Earth-type reference system, using the filtered rotated at least one measurement as an input.
12 . The method of claim 11 , further comprising:
displaying an image for a gaming system user according to the current orientation.
13 . The method of claim 11 , further comprising:
determining a position of a cursor on a display according to the current orientation.
14 . The method of claim 11 , wherein the method is performed by a processor of an apparatus controlled based on the current orientation.
15 . The method of claim 1 , wherein the transformation determined as a quaternion representing angular position of the gyroscope reference system relative to the sensor reference system.
16 . A non-transitory computer readable medium storing executable codes which when performed by a computer make the computer perform a method for filtering a measurement acquired in a sensor reference system, the method comprising:
determining a transformation from a sensor reference system to a gyroscope reference system;
rotating at least one measurement from the sensor reference system to the gyroscope reference system using the transformation;
filtering the rotated at least one measurement; and
rotating the filtered at least one measurement back into the sensor reference system.
17 . A filtering module, comprising:
a first input configured to receive a current value of an angular velocity of a device;
a second input configured to receive a measurement of an acceleration or a magnetic field from sensors mounted on the device;
an integration unit configured to receive the angular velocity and to determine a transformation to be applied to the received measurement;
a first rotation unit configured to receive the transformation and to apply the transformation to the received measurement;
a filter configured to modify the transformed measurement; and
a second rotation unit configured to receive the transformation, to apply an inverse of the transformation to the modified measurement and to output a result thereof.
18 . (canceled)
19 . The non-transitory computer readable medium of claim 16 , wherein the transformation is determined using a previous angular position of the gyroscope reference system in the sensor reference system, and an angular velocity measured in the sensor reference system.
20 . The filtering module of claim 17 , wherein the device is a mobile communication device
21 . The filtering module of claim 17 , wherein the angular velocity is measured by a 3D gyroscope.