Applying a correct factor derivative method for determining an orientation of a portable electronic device based on sense gravitation component linear accelerate filter data obtained

Abstract

A method for determining an orientation of a portable or mobile electronic device includes determining an orientation of the device using at least a first inertial motion sensor (e.g., a gyroscope) with which the portable electronic device is equipped. A correction factor is provided to the orientation of the electronic device using a feedback control signal based on motion data obtained from at least a second inertial motion sensor (e.g. an accelerometer) to reduce drift in motion data obtained from the first inertial sensor. Responsive to a loss of valid motion data from the first inertial motion sensor, a rate at which the correction factor is provided to the orientation of the portable electronic device is increased.

1 . A method for determining an orientation of a portable electronic device, comprising:
 obtaining an orientation of a portable electronic device using a gyroscope; and   when data from the gyroscope is lost, applying a correction factor to the orientation that is obtained using a correction factor obtained from at least one additional sensor.   
     
     
         2 . The method of  claim 1  further comprising applying the correction factor using a feedback control mechanism. 
     
     
         3 . The method of  claim 2  wherein the feedback control mechanism includes a proportional-integral-derivative (PID) feedback control mechanism. 
     
     
         4 . The method of  claim 3  further comprising using a proportional and integral responses of the PID feedback control mechanism and not a derivative response of the PID feedback control mechanism. 
     
     
         5 . The method of  claim 3  further comprising entering a fast correction mode of the PID feedback control mechanism by increasing a proportional response of the PID feedback control mechanism and suppressing an integral response of the PID feedback control mechanism. 
     
     
         6 . The method of  claim 5  further comprising exiting the fast correction mode when data from the gyroscope again becomes available. 
     
     
         7 . The method of  claim 1  wherein the at least one additional sensor includes an accelerometer. 
     
     
         8 . The method of  claim 1  wherein the at least one additional sensor includes a magnetometer. 
     
     
         9 . The method of  claim 7  further comprising filtering data from the accelerometer by an amount that decreases as a rotational speed measured by the gyroscope increases. 
     
     
         10 . The method of  claim 5  in which the fast correction mode is entered and exited at a rate greater than a linear rate. 
     
     
         11 . The method of  claim 10  in which the rate greater than the linear rate is a hyperbolic rate. 
     
     
         12 . A portable electronic device, comprising:
 at least first and second inertial sensors for sensing motion of the device, the first inertial sensor providing motion data of a first type and the second inertial sensor providing motion data of a second type different from the first type;   one or more processors for executing computer-executable instructions; and   one or more computer-readable storage media for storing the machine-executable instructions, the instructions, when executed by the one more processors, implementing processing logic that supplements the motion data of the first type when data from the first inertial sensor drifts or is lost, the motion data of the first type being supplemented using a correction factor based on motion data obtained from the second inertial sensor.   
     
     
         13 . The portable electronic device of  claim 12  in which the first inertial sensor is a gyroscope providing rotational motion data and an orientation derived from the rotational motion is a relative orientation of the device. 
     
     
         14 . The portable electronic device of  claim 12  in which the processing logic initializes the rotational motion data using a feedback control signal to obtain an absolute rotation motion of the device. 
     
     
         15 . The portable electronic device of  claim 12  in which the second inertial sensor is an accelerometer sensing a total acceleration that includes a gravitational component and a linear acceleration component. 
     
     
         16 . The portable electronic device of  claim 15  further comprising a variable low pass filter which filters data obtained by the second inertial sensor by an amount that depends at least in part on a sensed rotational rate of the device. 
     
     
         17 . The portable electronic device of  claim 16  wherein the amount of filtering performed on the data obtained by the second inertial sensor is reduced while the sensed rotational rate of the device increases. 
     
     
         18 . A mobile electronic device, comprising:
 at least first and second inertial sensors for sensing motion of the device;   one or more processors for executing computer-executable instructions which, when executed by the one or more processors, perform a method comprising the steps of:   determining an orientation of the mobile electronic device using the first inertial motion sensor; and   providing a correction factor to the determined orientation of the mobile electronic device when data from the first inertial sensor drifts or is lost, based on a feedback control mechanism that uses motion data obtained from the second inertial sensor.   
     
     
         19 . The mobile electronic device of  claim 18  in which the first inertial motion sensor is a gyroscope detecting rotational motion of the device and the second inertial motion sensor is an accelerometer sensing a total acceleration that includes a gravitational component and a linear acceleration component, said correction factor to the determined orientation of the mobile electronic device being provided when the accelerometer senses a total acceleration equal to the gravitational component within a predefined threshold. 
     
     
         20 . The mobile electronic device of  claim 19  further comprising using a variable low pass filter to filter the motion data obtained by the accelerometer by an amount that depends at least in part on a sensed rotational rate of the device.