Device and method for combining samples from an inertial measurement sensor cluster

• US 8,756,995 B2
• Filed: 06/24/2013
• Issued: 06/24/2014
• Est. Priority Date: 11/04/2008
• Status: Active Grant

• Current Assignee: Elbit Systems Limited
• Original Assignee: Elbit Systems Limited
• Inventors: Tzidon, Dekel, Braginsky, Alex
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US13/924,743
• Publication Number:
  US 20130297250A1
• Time in Patent Office: 365 Days
• Field of Search: 735/140.1, 73510-511, 731/78.R, 702/1, 702/33, 702/55, 701/200, 701/207, 701/220, 701/221, 701/400, 701/408, 701/420, 701/421
• US Class Current: 73/510
• CPC Class Codes: G01C 19/5776 Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719
• CPC Class Codes: G01C 21/10 by using measurements of speed or acceleration G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01C 21/188 for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems
• CPC Class Codes: G01P 13/00 Indicating or recording presence, absence, or direction, of movement electric switches H01H; counting moving objects G06M7/00
• CPC Class Codes: G01P 15/08 with conversion into electric or magnetic values

Abstract

Device and method for providing inertial indications with high accuracy using micro inertial sensors with inherent very small size and low accuracy. The device and method of the invention disclose use of the cluster of multiple micro inertial sensors to receive from the multiple sensors an equivalent single inertial indication with high accuracy based on the multiple independent indications and mathematical manipulations for averaging the plurality of single readings and for eliminating common deviations based, for example, on measurements of the deviation of the single readings.

Claims

1. An inertial measurement device comprising:

at least one sensor cluster, each of said at least one sensor cluster comprising a plurality of micro inertial sensors being oriented substantially along same respective axis, for sampling movement of said inertial measurement device with respect to each of said respective axis of a plurality of axes of a reference frame, each of said plurality of micro inertial sensors exhibits a respective random error; and

a summing unit to receive individual respective samples from at least some of said plurality of micro inertial sensors indicative of said movement with respect to said respective axis and to reduce a total random error in an equivalent vector that is calculated by summing said individual respective samples by said summing unit, wherein said equivalent vector is indicative of sampled said movement.

2. The device as claimed in claim 1, further comprising a computing unit operative to receive stored misalignment data so as to compensate for misalignment of said plurality of micro inertial sensors in said at least one sensor cluster in the calculation of said equivalent vector.

3. The device as claimed in claim 1, wherein said plurality of micro inertial sensors is of the micro-electromechanical sensor type.

4. The device as claimed in claim 1, wherein said plurality of micro inertial sensors comprises more than one micro-electromechanical sensor.

5. The device as claimed in claim 1, wherein said plurality of micro inertial sensors comprises more than one gyroscope sensor.

6. The device as claimed in claim 1, wherein at least some of said plurality of micro inertial sensors are substantially aligned with each one of said axes of a three-dimensional said reference frame.

7. The device as claimed in claim 1, wherein said plurality of micro inertial sensors comprises an integrated sensor cluster.

8. The device as claimed in claim 1, wherein at least some in said plurality of micro inertial sensors are spatially displaced by respective known amounts from a pivot axis of said at least one sensor cluster.

9. The device as claimed in claim 1, wherein an orientation of an axis of each one of said plurality of micro inertial sensors is angularly misaligned by a respective known amount with respect to an orientation of said axis of respective said at least one sensor cluster.

10. The device as claimed in claim 2, wherein said computing unit combines separate outputs of said plurality of micro inertial sensors to yield a compensated output for each respective one of said at least one sensor cluster.

11. The device as claimed in claim 10, wherein said device communicates with at least one additional device selected from a list comprising a Global Positioning System receiver, and a zero-velocity update sensor.

12. The device as claimed in claim 10, wherein said device is worn or carried by a person.

13. An inertial measurement method comprising:

reading separate respective outputs of at least some in a plurality of micro inertial sensors of a sensor cluster, said plurality of micro inertial sensors being oriented substantially along same respective axis in a plurality of axes of a reference frame, each of said plurality of micro inertial sensors exhibits a respective random error; and

combining said separate respective outputs to yield a single combined output of said sensor cluster, so to reduce a total random error in said single combined output, said combined output indicative of movement of said sensor cluster in said reference frame.

14. The method as claimed in claim 13, further comprising the steps of:

estimating an error in said single combined output of said sensor cluster, according to an error model of each of said plurality of micro inertial sensors;

calculating a correction to compensate for said error; and

applying said correction to said single combined output of said sensor cluster to yield a corrected value.

15. The method as claimed in claim 14, further comprising the steps of:

reading an output of at least one additional device selected from a list comprising a Global Positioning System receiver, and a zero-velocity update sensor; and

utilizing said output of said at least one additional device in estimating said error in said single combined output of said sensor cluster.

16. The method as claimed in claim 13, further comprising the steps of:

providing an amount of displacement of each of said plurality of micro inertial sensors in relation to a pivot axis of said sensor cluster, each of said amount of displacement being stored by a memory device; and

adjusting said separate respective outputs of each of said plurality of micro inertial sensors according to each of respective said amount of displacement.

17. The method as claimed in claim 13, further comprising the steps of:

providing an amount of deviation of an axis of each of respective said plurality of micro inertial sensors in relation to respective said axis of said sensor cluster, said amount of deviation being stored by a memory device; and

adjusting said separate respective outputs of each of said plurality of micro inertial sensors according to respective said amount of deviation.