Correction of motion sensor and global navigation satellite system data of a mobile device in a vehicle

Abstract

Aspects of the disclosure relate to initializing an inertial navigation system (INS) of a mobile device. Accelerometer bias of a plurality of accelerometers of the mobile device, and gyroscope bias of a plurality of gyroscopes of the mobile device, are determined. A first spatial relationship between a first frame of reference of the mobile device and a second frame of reference of a vehicle transporting the mobile device is determined. A second spatial relationship between the first frame of reference and a third frame of reference of a surface beneath the vehicle is determined. Each of the frames of reference are determined based on output of at least two of the GNSS receiver, the plurality of accelerometers, or the plurality of gyroscopes. The INS is provided with the accelerometer bias, the gyroscope bias, the first spatial relationship, and the second spatial relationship to initialize the INS.

What is claimed is: 
     
         1 . A mobile device, comprising:
 a global navigation satellite system (GNSS) receiver;   one or more accelerometers;   one or more gyroscopes;   an inertial navigation system (INS) operationally coupled to the GNSS receiver, the one or more accelerometers, and the one or more gyroscopes; and   a motion-bias-orientation circuit operationally coupled to the GNSS receiver, the one or more accelerometers, the one or more gyroscopes, and the INS, the motion-bias-orientation circuit is configured to:
 determine at least one of:
 accelerometer bias of the one or more accelerometers based on output of the one or more accelerometers, or 
 gyroscope bias of the one or more gyroscopes based on output of the one or more gyroscopes, 
 
 determine a first spatial relationship between a first frame of reference of the mobile device and a second frame of reference of a vehicle transporting the mobile device, based on output from the GNSS receiver, the one or more accelerometers, the one or more gyroscopes, or any combination thereof, 
 determine a second spatial relationship between the first frame of reference of the mobile device and a third frame of reference of a surface beneath the vehicle, based on output from the GNSS receiver, the one or more accelerometers, the one or more gyroscopes, or any combination thereof, and 
 initialize the INS with the at least one of the accelerometer bias or the gyroscope bias, the first spatial relationship, and the second spatial relationship in response to determining that the mobile device is stationary relative to the vehicle transporting the mobile device. 
   
     
     
         2 . The mobile device of  claim 1 , further comprising a non-vehicle motion detector operationally coupled to the one or more gyroscopes and configured to classify motion of the mobile device according to both a first state in which the motion of the mobile device includes non-vehicle motion and a second state in which the motion of the mobile device is due to vehicle motion alone and determine that the mobile device is stationary relative to the vehicle transporting the mobile device when the motion of the mobile device is in the second state. 
     
     
         3 . The mobile device of  claim 2 , wherein the motion-bias-orientation circuit initializes the INS with the at least one of the accelerometer bias or the gyroscope bias, the first spatial relationship, and the second spatial relationship upon a change of state from the first state to the second state. 
     
     
         4 . The mobile device of  claim 2 , wherein the motion-bias-orientation circuit is further configured to:
 re-determine the first spatial relationship;   re-determine the second spatial relationship; and   initialize the INS with the at least one of the accelerometer bias or the gyroscope bias, the re-determined first spatial relationship, and the re-determined second spatial relationship upon a change of state from the first state to the second state.   
     
     
         5 . The mobile device of  claim 2 , wherein the non-vehicle motion detector is further configured to:
 determine a difference between angles of a first rotation vector measured by the one or more gyroscopes at a first time and a second rotation vector measured by the one or more gyroscopes at a second time; and   indicate that the mobile device is in the second state if the difference between the angles is less than a predetermined value.   
     
     
         6 . The mobile device of  claim 5 , wherein a difference in time between the first time and the second time is a time between successive refreshes of data determined from the one or more gyroscopes. 
     
     
         7 . The mobile device of  claim 1 , wherein the first spatial relationship is expressed as a first set of Euler angles, a first set of Tait-Bryan angles, or a first rotation matrix and the second spatial relationship is expressed as a second set of Euler angles, a second set of Tait-Bryan angles, or a second rotation matrix. 
     
     
         8 . The mobile device of  claim 1 , wherein the one or more accelerometers measure acceleration along three orthogonal axes of the first frame of reference and the one or more gyroscopes measure rotation about the three orthogonal axes. 
     
     
         9 . A method of initializing an inertial navigation system (INS) of a mobile device, the method operational at the mobile device, comprising:
 determining at least one of:
 accelerometer bias of one or more accelerometers of the mobile device based on output of the one or more accelerometers, or 
 gyroscope bias of one or more gyroscopes of the mobile device based on output of the one or more gyroscopes; 
   determining a first spatial relationship between a first frame of reference of the mobile device and a second frame of reference of a vehicle transporting the mobile device, based on output of a global navigation satellite system (GNSS) receiver, the one or more accelerometers, the one or more gyroscopes, or any combination thereof;   determining a second spatial relationship between the first frame of reference of the mobile device and a third frame of reference of a surface beneath the vehicle, based on output of the GNSS receiver, the one or more accelerometers, the one or more gyroscopes, or any combination thereof; and   initializing the INS with the at least one of the accelerometer bias or the gyroscope bias, the first spatial relationship, and the second spatial relationship in response to determining that the mobile device is stationary relative to the vehicle transporting the mobile device.   
     
     
         10 . The method of  claim 9 , further comprising:
 classifying, by a non-vehicle motion detector operationally coupled to the one or more gyroscopes, motion of the mobile device according to both a first state in which the motion of the mobile device includes non-vehicle motion and a second state in which the motion of the mobile device is due to vehicle motion alone, and   determining that the mobile device is stationary relative to the vehicle transporting the mobile device when the motion of the mobile device is in the second state.   
     
     
         11 . The method of  claim 10 , further comprising initializing the INS with the at least one of the accelerometer bias or the gyroscope bias, the first spatial relationship, and the second spatial relationship upon a change of state from the first state to the second state. 
     
     
         12 . The method of  claim 10 , further comprising:
 re-determining the first spatial relationship,   re-determining the second spatial relationship, and   initializing the INS with the at least one of the accelerometer bias or the gyroscope bias, the re-determined first spatial relationship, and the re-determined second spatial relationship upon a change of state from the first state to the second state.   
     
     
         13 . The method of  claim 10 , further comprising:
 determining, by the non-vehicle motion detector, a difference between angles of a first rotation vector measured by the one or more gyroscopes at a first time and a second rotation vector measured by the one or more gyroscopes at a second time; and   indicating that the mobile device is in the second state if the difference between the angles is less than a predetermined value.   
     
     
         14 . The method of  claim 13 , wherein a difference in time between the first time and the second time is a time between successive refreshes of data determined from the one or more gyroscopes. 
     
     
         15 . The method of  claim 9 , wherein the first spatial relationship is expressed as a first set of Euler angles, a first set of Tait-Bryan angles, or a first rotation matrix and the second spatial relationship is expressed as a second set of Euler angles, a second set of Tait-Bryan angles, or a second rotation matrix. 
     
     
         16 . The method of  claim 9 , wherein determining the at least one of the accelerometer bias of the one or more accelerometers or the gyroscope bias of the one or more gyroscopes comprises:
 determining that the vehicle and the mobile device are stationary;   determining a static acceleration vector from the one or more accelerometers while the vehicle and the mobile device are stationary;   determining a static rotation vector from the one or more gyroscopes while the vehicle and the mobile device are stationary; and   at least one of:
 subtracting a gravity vector from the static acceleration vector to determine the accelerometer bias, or 
 subtracting the gravity vector from the static rotation vector to determine the gyroscope bias. 
   
     
     
         17 . The method of  claim 9 , wherein determining the first spatial relationship between the first frame of reference of the mobile device and the second frame of reference of the vehicle comprises:
 determining a forward acceleration vector in a horizontal plane that is representative of acceleration of the vehicle moving in a straight-line direction;   determining a right-forward acceleration vector in the horizontal plane that is representative of acceleration of the vehicle moving in a right-forward turn direction;   determining an up acceleration vector having a direction that is perpendicular to the horizontal plane based on the forward acceleration vector and the right-forward acceleration vector; and   determining the first spatial relationship based on the forward acceleration vector, the right-forward acceleration vector, and the up acceleration vector.   
     
     
         18 . The method of  claim 17 , wherein determining the up acceleration vector having the direction that is perpendicular to the horizontal plane based on the forward acceleration vector and the right-forward acceleration vector comprises:
 determining a cross product of the right-forward acceleration vector and the forward acceleration vector.   
     
     
         19 . The method of  claim 17 , wherein the mobile device determines that the vehicle is moving on the horizontal plane by determining that an angular difference between a static acceleration vector and a rotation vector as measured using the one or more gyroscopes is less than a predetermined value. 
     
     
         20 . The method of  claim 17 , wherein the mobile device determines that the vehicle is moving on the horizontal plane by determining that a dot product of a static acceleration vector and a rotation vector as measured using the one or more gyroscopes is greater than a predetermined value. 
     
     
         21 . The method of  claim 9 , further comprising:
 determining an east acceleration vector in a horizontal plane that is representative of acceleration of the vehicle transporting the mobile device moving in an east straight-line direction;   determining an east-north acceleration vector in the horizontal plane that is representative of acceleration of the vehicle moving in an east-north turn direction;   determining an up acceleration vector having a direction that is perpendicular to the horizontal plane based on the east acceleration vector and the east-north acceleration vector; and   determining the first spatial relationship based on the east acceleration vector, the east-north acceleration vector, and the up acceleration vector.   
     
     
         22 . The method of  claim 9 , further comprising:
 determining that the vehicle and the mobile device are stationary;   determining a static acceleration vector from the one or more accelerometers while the vehicle and the mobile device are stationary; and   at least one of:
 determining the east acceleration vector in a horizontal plane by:
 determining that the vehicle is moving on an east straight-line direction, 
 determining a first acceleration vector from the one or more accelerometers while the vehicle is moving in the east straight-line direction, and 
 subtracting the static acceleration vector from the first acceleration vector; or 
 
 determining the east-north acceleration vector in the horizontal plane by:
 determining that the vehicle is moving in an east-north turn direction, 
 determining a second acceleration vector from the one or more accelerometers while the vehicle is moving in the east-north turn direction, and 
 subtracting the static acceleration vector from the second acceleration vector. 
 
   
     
     
         23 . A non-transitory machine-readable storage medium having one or more instructions stored thereon, which when executed by at least one processing circuit of a mobile device causes the at least one processing circuit to:
 determine at least one of:
 accelerometer bias of one or more accelerometers of the mobile device based on output of the one or more accelerometers, or 
 gyroscope bias of one or more gyroscopes of the mobile device based on output of the one or more gyroscopes; 
   determine a first spatial relationship between a first frame of reference of the mobile device and a second frame of reference of a vehicle transporting the mobile device, based on output of a global navigation satellite system (GNSS) receiver, the one or more accelerometers, the one or more gyroscopes, or any combination thereof;   determine a second spatial relationship between the first frame of reference of the mobile device and a third frame of reference of a surface beneath the vehicle, based on output of the GNSS receiver, the one or more accelerometers, the one or more gyroscopes, or any combination thereof; and   initialize an inertial navigation system (INS) of the mobile device with the at least one of the accelerometer bias or the gyroscope bias, the first spatial relationship, and the second spatial relationship in response to determining that the mobile device is stationary relative to the vehicle transporting the mobile device.   
     
     
         24 . The non-transitory machine-readable storage medium of  claim 23 , wherein the one or more instructions further cause a non-vehicle motion detector operationally coupled to the one or more gyroscopes and configured to classify motion of the mobile device according to both a first state in which the motion of the mobile device includes non-vehicle motion and a second state in which the motion of the mobile device is due to vehicle motion alone to determine that the mobile device is stationary relative to the vehicle transporting the mobile device when the motion of the mobile device is in the second state. 
     
     
         25 . The non-transitory machine-readable storage medium of  claim 24 , wherein the one or more instructions further cause the at least one processing circuit to initialize the INS with the at least one of the accelerometer bias or the gyroscope bias, the first spatial relationship, and the second spatial relationship upon a change of state from the first state to the second state. 
     
     
         26 . The non-transitory machine-readable storage medium of  claim 24 , wherein the one or more instructions further cause the at least one processing circuit to:
 re-determine the first spatial relationship;   re-determine the second spatial relationship; and   initialize the INS with the at least one of the accelerometer bias or the gyroscope bias, the re-determined first spatial relationship, and the re-determined second spatial relationship upon a change of state from the first state to the second state.   
     
     
         27 . A mobile device, comprising:
 a global navigation satellite system (GNSS) receiver;   one or more accelerometers;   one or more gyroscopes;   an inertial navigation system (INS) operationally coupled to the GNSS receiver, the one or more accelerometers, and the one or more gyroscopes; and   at least one of:
 means for determining accelerometer bias of the one or more accelerometers based on output of the one or more accelerometers, or 
 means for determining gyroscope bias of the one or more gyroscopes based on output of the one or more gyroscopes; 
   means for determining a first spatial relationship between a first frame of reference of the mobile device and a second frame of reference of a vehicle transporting the mobile device, based on output from the GNSS receiver, the one or more accelerometers, the one or more gyroscopes, or any combination thereof;   means for determining a second spatial relationship between the first frame of reference of the mobile device and a third frame of reference of a surface beneath the vehicle, based on output from the GNSS receiver, the one or more accelerometers, the one or more gyroscopes, or any combination thereof; and   means for initializing the INS with the at least one of the accelerometer bias or the gyroscope bias, the first spatial relationship, and the second spatial relationship in response to determining that the mobile device is stationary relative to the vehicle transporting the mobile device.   
     
     
         28 . The mobile device of  claim 27 , further comprising means for classifying motion of the mobile device according to both a first state in which the motion of the mobile device includes non-vehicle motion and a second state in which the motion of the mobile device is due to vehicle motion alone and determine that the mobile device is stationary relative to the vehicle transporting the mobile device when the motion of the mobile device is in the second state. 
     
     
         29 . The mobile device of  claim 28 , wherein the means for initializing the INS initializes the INS with the at least one of the accelerometer bias or the gyroscope bias, the first spatial relationship, and the second spatial relationship upon a change of state from the first state to the second state. 
     
     
         30 . The mobile device of  claim 28 , wherein:
 the means for determining the first spatial relationship re-determines the first spatial relationship;   the means for determining the second spatial relationship re-determines the second spatial relationship; and   the means for initializing the INS initializes the INS with the at least one of the accelerometer bias or the gyroscope bias, the re-determined first spatial relationship, and the re-determined second spatial relationship upon a change of state from the first state to the second state.