Estimation of an initial condition inertial reference frame
First Claim
1. An inertial device for determining an initial condition inertial reference frame for a body, the inertial device comprising:
- at least one inertial measurement unit (IMU) configured to provide rotation information along at least one axis;
one or more processing devices coupled to the at least one IMU;
one or more memory devices coupled to the one or more processing devices, wherein the one or more memory devices include instructions which, when executed by the one or more memory devices, cause the one or more processing devices to;
receive rotation information from the IMU along at least one axis, the rotation information starting at a first time;
estimate a rate profile for the body from a second time that is prior to the first time, to the first time, based on a model spin-up characteristic for the body corresponding to a time prior to the first time through at least the first time;
integrate across the rate profile to determine an accumulated rotational angle for the body from the second time to the first time; and
send an indication of the accumulated rotation angle for later use.
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Abstract
An inertial device for determining an initial condition reference frame for a body is provided. The inertial device includes at least one inertial measurement unit, one or more processing devices, and one or more memory devices. The inertial measurement unit provides rotation information along at least one axis to the one or more processing devices. The one or more processing devices use the rotation information to estimate the current attitude of the body, based on estimates of a total rotation angle experienced by the body from the beginning of body motion to when the inertial measurement unit initialized.
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Citations
20 Claims
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1. An inertial device for determining an initial condition inertial reference frame for a body, the inertial device comprising:
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at least one inertial measurement unit (IMU) configured to provide rotation information along at least one axis; one or more processing devices coupled to the at least one IMU; one or more memory devices coupled to the one or more processing devices, wherein the one or more memory devices include instructions which, when executed by the one or more memory devices, cause the one or more processing devices to; receive rotation information from the IMU along at least one axis, the rotation information starting at a first time; estimate a rate profile for the body from a second time that is prior to the first time, to the first time, based on a model spin-up characteristic for the body corresponding to a time prior to the first time through at least the first time; integrate across the rate profile to determine an accumulated rotational angle for the body from the second time to the first time; and send an indication of the accumulated rotation angle for later use. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of estimating an initial condition inertial reference frame for an object, the method comprising:
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determining a model of rotation for the object, along at least one axis, by one or more processing devices, the model corresponding to a time prior to the first time; sampling rotation information from an inertial measurement unit along the at least one axis, the rotation information starting at a first time; performing a first fit to the sampled rotation information to a second time, which is prior to the first time; applying a model spin-up characteristic that describes body rotational rate for each of the at least one axis from the first time to the second time; estimating a rate profile for the object along the at least one axis by performing a second fit through the model spin-up characteristic and first fit; integrating across the rate profile to determine an accumulated rotational angle for the body from the second time to the first time along the at least one axis populating a rotation matrix with the accumulated rotational angle information and determining object orientation; adjusting the accumulated rotation angle with incremental angle changes in each measured axis. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A non-transitory computer readable medium comprising computer readable code, wherein the code comprises instructions that cause a computer device to:
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receive rotation information from an inertial measurement unit (IMU) along at least one axis, the rotation information starting at a first time; estimate a rate profile for a body corresponding to the IMU from a second time that is prior to the first time, to the first time, based on a model spin-up characteristic for the body corresponding to a time prior to the first time through at least the first time; integrate across the rate profile to determine an accumulated rotational angle for the body from the second time to the first time; and provide the accumulated rotation angle for later use. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification