System and method for determining a uniform external magnetic field
First Claim
1. A method comprising:
- at a processing apparatus having one or more processors and memory storing one or more programs that when executed by the one or more processors cause the respective processing apparatus to perform the method,generating navigational state estimates for a device having a plurality of sensors, the plurality of sensors including a magnetometer, wherein the processing apparatus has a plurality of modes of operation including;
a magnetometer-assisted mode of operation in which measurements from the magnetometer are used to estimate the navigational state of the device; and
an alternate mode of operation in which measurements from a subset of sensors of the plurality of sensors that does not include the magnetometer are used to estimate the navigational state of the device;
for a respective time period, operating in the alternate mode of operation;
during the respective time period;
collecting a plurality of magnetometer measurements;
determining a first estimated direction of the external magnetic field based on the plurality of magnetometer measurements;
determining a second estimated direction of the external magnetic field based on measurements from one or more of the other sensors and a predetermined relationship between an estimated orientation of the device and the external magnetic field; and
determining whether the plurality of magnetometer measurements meet predefined measurement-consistency requirements while the first estimated magnetic field is not consistent with the second estimated magnetic field;
in accordance with the determination that the plurality of magnetometer measurements meet predefined measurement-consistency requirements while the first estimated magnetic field is not consistent with the second estimated magnetic field, transitioning to the magnetometer-assisted mode of operation, including adjusting the estimate of the navigational state of the device in accordance with a difference between the first estimated magnetic field and the second estimated magnetic field; and
in accordance with the determination that the plurality of magnetometer measurements do not meet predefined measurement-consistency requirements, continuing to operate in the alternate mode of operation.
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Accused Products
Abstract
A processing apparatus, optionally integrated into a device having a plurality of sensors including a magnetometer, generates navigational state estimates for the device. The processing apparatus has a magnetometer-assisted mode of operation in which measurements from the magnetometer are used to estimate the navigational state and an alternate mode of operation in which the navigational state of the device is estimated without measurements from the magnetometer. For a respective time period, the processing apparatus operates in the alternate mode of operation. During the respective time period, the processing apparatus collects a plurality of magnetometer measurements and determines whether they meet measurement-consistency requirements. If the measurements meet the measurement-consistency requirements, the processing apparatus transitions to the magnetometer-assisted mode of operation. If the measurements do not meet the measurement-consistency requirements, the processing apparatus continues to operate in the alternate mode of operation.
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Citations
20 Claims
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1. A method comprising:
at a processing apparatus having one or more processors and memory storing one or more programs that when executed by the one or more processors cause the respective processing apparatus to perform the method, generating navigational state estimates for a device having a plurality of sensors, the plurality of sensors including a magnetometer, wherein the processing apparatus has a plurality of modes of operation including; a magnetometer-assisted mode of operation in which measurements from the magnetometer are used to estimate the navigational state of the device; and an alternate mode of operation in which measurements from a subset of sensors of the plurality of sensors that does not include the magnetometer are used to estimate the navigational state of the device;
for a respective time period, operating in the alternate mode of operation;
during the respective time period;collecting a plurality of magnetometer measurements; determining a first estimated direction of the external magnetic field based on the plurality of magnetometer measurements; determining a second estimated direction of the external magnetic field based on measurements from one or more of the other sensors and a predetermined relationship between an estimated orientation of the device and the external magnetic field; and determining whether the plurality of magnetometer measurements meet predefined measurement-consistency requirements while the first estimated magnetic field is not consistent with the second estimated magnetic field; in accordance with the determination that the plurality of magnetometer measurements meet predefined measurement-consistency requirements while the first estimated magnetic field is not consistent with the second estimated magnetic field, transitioning to the magnetometer-assisted mode of operation, including adjusting the estimate of the navigational state of the device in accordance with a difference between the first estimated magnetic field and the second estimated magnetic field; and in accordance with the determination that the plurality of magnetometer measurements do not meet predefined measurement-consistency requirements, continuing to operate in the alternate mode of operation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A computer system, comprising:
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a processing apparatus including one or more processors and memory; and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions for; generating navigational state estimates for a device having a plurality of sensors, the plurality of sensors including a magnetometer, wherein the processing apparatus has a plurality of modes of operation including; a magnetometer-assisted mode of operation in which measurements from the magnetometer are used to estimate the navigational state of the device; and an alternate mode of operation in which measurements from a subset of sensors of the plurality of sensors that does not include the magnetometer are used to estimate the navigational state of the device; and for a respective time period, operating the processing apparatus in the alternate mode of operation; during the respective time period; collecting a plurality of magnetometer measurements; determining a first estimated direction of the external magnetic field based on the plurality of magnetometer measurements; determining a second estimated direction of the external magnetic field based on measurements from one or more of the other sensors and a predetermined relationship between an estimated orientation of the device and the external magnetic field; and determining whether the plurality of magnetometer measurements meet predefined measurement-consistency requirements while the first estimated magnetic field is not consistent with the second estimated magnetic field; in accordance with the determination that the plurality of magnetometer measurements meet predefined measurement-consistency requirements while the first estimated magnetic field is not consistent with the second estimated magnetic field, transitioning to the magnetometer-assisted mode of operation, including adjusting the estimate of the navigational state of the device in accordance with a difference between the first estimated magnetic field and the second estimated magnetic field; and in accordance with the determination that the plurality of magnetometer measurements do not meet predefined measurement-consistency requirements, continuing to operate the processing apparatus in the alternate mode of operation. - View Dependent Claims (14, 15, 16)
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17. A non-transitory computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by a processing apparatus with one or more processors, cause the processing apparatus to:
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generate navigational state estimates for a device having a plurality of sensors, the plurality of sensors including a magnetometer, wherein the processing apparatus has a plurality of modes of operation including; a magnetometer-assisted mode of operation in which measurements from the magnetometer are used to estimate the navigational state of the device; and an alternate mode of operation in which measurements from a subset of sensors of the plurality of sensors that does not include the magnetometer are used to estimate the navigational state of the device; and for a respective time period, operate the processing apparatus in the alternate mode of operation; during the respective time period; collect a plurality of magnetometer measurements; determine a first estimated direction of the external magnetic field based on the plurality of magnetometer measurements; determine a second estimated direction of the external magnetic field based on measurements from one or more of the other sensors and a predetermined relationship between an estimated orientation of the device and the external magnetic field; and determine whether the plurality of magnetometer measurements meet predefined measurement-consistency requirements while the first estimated magnetic field is not consistent with the second estimated magnetic field; in accordance with the determination that the plurality of magnetometer measurements meet predefined measurement-consistency requirements while the first estimated magnetic field is not consistent with the second estimated magnetic field, transition to the magnetometer-assisted mode of operation, including adjusting the estimate of the navigational state of the device in accordance with a difference between the first estimated magnetic field and the second estimated magnetic field; and in accordance with the determination that the plurality of magnetometer measurements do not meet predefined measurement-consistency requirements, continue to operate the processing apparatus in the alternate mode of operation. - View Dependent Claims (18, 19, 20)
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Specification