Calibration for three dimensional motion sensor
First Claim
1. A method for simultaneously calibrating several electronic devices having inertial measurement units (IMUs), the method comprising:
- placing several electronic devices having embedded IMUs in a testing apparatus;
placing a separate true IMU in the testing apparatus;
moving the testing apparatus in a sequence of testing positions;
retrieving, at each testing position, an IMU output from at least one embedded IMU of each of the several electronic devices and a true IMU output from the true IMU;
calculating, for each electronic device, sensitivity and offset factors for adjusting the IMU output of the at least one embedded IMU to approach the true IMU output of the true IMU; and
storing, in storage of each electronic device, the calculated sensitivity and offset factors corresponding to the electronic device.
1 Assignment
0 Petitions
Accused Products
Abstract
An electronic device can include an inertial measurement unit (IMU) operative to monitor the movement of the electronic device. The IMU used in the device can be inaccurate due to the manufacturing process used to construct the IMU and to incorporate the IMU in the electronic device. To correct the IMU output, the electronic device in which the IMU is incorporated can be placed in a testing apparatus that moves the device to known orientations. The IMU output at the known orientations can be compared to an expected true IMU output, and correction factors (e.g., sensitivity and offset matrices) can be calculated. The correction factors can be stored in the device, and applied to the IMU output to provide a true output. The testing apparatus can include a fixture placed in a gimbal movable around three axes.
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Citations
23 Claims
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1. A method for simultaneously calibrating several electronic devices having inertial measurement units (IMUs), the method comprising:
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placing several electronic devices having embedded IMUs in a testing apparatus; placing a separate true IMU in the testing apparatus; moving the testing apparatus in a sequence of testing positions; retrieving, at each testing position, an IMU output from at least one embedded IMU of each of the several electronic devices and a true IMU output from the true IMU; calculating, for each electronic device, sensitivity and offset factors for adjusting the IMU output of the at least one embedded IMU to approach the true IMU output of the true IMU; and storing, in storage of each electronic device, the calculated sensitivity and offset factors corresponding to the electronic device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 20, 21, 22, 23)
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9. A testing apparatus for calibrating inertial measurement units embedded in a plurality of electronic devices, the testing apparatus comprising a processor operative to:
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direct the plurality of electronic devices and a separate inertial measurement unit to move in a sequence of positions while the plurality of electronic devices are placed in the testing apparatus; receive, from an inertial measurement unit embedded in each electronic device of the plurality of electronic devices, an output corresponding to each of the sequence of positions in a reference frame associated with the inertial measurement unit embedded in each electronic device; receive, from the separate inertial measurement unit, an output in a reference frame associated with at least one electronic device of the plurality of electronic devices; make a comparison of the received output from the inertial measurement unit embedded in each electronic device to the output of the separate inertial measurement unit for each of the sequence of positions; calculate correction factors for the inertial measurement unit embedded in each electronic device, wherein calculating the correction factors for the inertial measurement unit embedded in each electronic device comprises converting the reference frame associated with the inertial measurement unit embedded in each electronic device to the reference frame associated with the at least one electronic device based on the comparison; and direct each electronic device of the plurality of electronic devices to store the correction factors. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method for calibrating a plurality of electronic devices, the method comprising:
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placing the plurality of electronic devices in a testing apparatus, wherein each electronic device of the plurality of electronic devices includes a first inertial measurement unit (IMU) oriented in an IMU reference frame; moving the testing apparatus through a plurality of different orientations; receiving a first output from the first IMU in each electronic device as the testing apparatus is moved; receiving, from a second IMU of the testing apparatus, a second output as the testing apparatus is moved, wherein the second IMU is oriented in a testing apparatus reference frame; for each electronic device of the plurality of electronic devices, comparing the first and the second outputs at a same moment in time to calculate a correction factor for transforming the IMU reference frame to the testing apparatus reference frame; and for each electronic device of the plurality of electronic devices, applying the calculated correction factor to the electronic device, wherein the correction factor is stored in memory of the electronic device. - View Dependent Claims (16, 17, 18, 19)
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Specification