Management System for MEMS Inertial Sensors

• US 20090293615A1
• Filed: 03/20/2009
• Published: 12/03/2009
• Est. Priority Date: 03/21/2008
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Lee, James M.
• Granted Patent: US 8,220,329 B2
• Time in Patent Office: Days
• US Class Current: 73/514.01
• CPC Class Codes: G01P 1/127 for acceleration values
• CPC Class Codes: G01P 15/0891 with indication of predetermined acceleration values G01P15/135 takes precedence
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G11B 19/043 by detecting a free-fall condition

Abstract

A MEMS system includes an inertial sensor having sensor circuitry and management circuitry implemented with the sensor circuitry. The management circuitry includes a detection module that detects a condition of the system and a management module that coordinates the functionality of the inertial sensor and the detection module based on the detected condition.

Claims

1. A MEMS system comprising:

an inertial sensor having sensor circuitry; and

management circuitry implemented with the sensor circuitry, the management circuitry including a detection module that detects a condition of the system and a management module that coordinates the functionality of the inertial sensor and the detection module based on the detected condition.

2. The system of claim 1, wherein the management circuitry further includes memory operatively coupled with the management module and the detection module, the memory capable of storing data values produced by the inertial sensor.

3. The system of claim 2, wherein the condition is a designated amount of data values stored in the memory.

4. The system of claim 3, further comprising a microprocessor in communication with the inertial sensor and the management circuitry, wherein the management module informs the microprocessor that the designated amount of data values are stored in the memory.

5. The system of claim 2, wherein the memory stores the data values received by the inertial sensor in a first-in-first-out buffer type of configuration, a stream buffer type of configuration, or both.

6. The system of claim 1, wherein the condition is an activity condition of the inertial sensor, and the detection module determines the activity condition by calculating a change in acceleration and comparing the change in acceleration to a threshold, wherein the change in acceleration is determined using an acceleration bias captured by the inertial sensor and a measured acceleration produced by the inertial sensor.

7. The system of claim 6, wherein the measured acceleration is produced by the inertial sensor at a predetermined period of time, and the management module modifies the predetermined period of time when activity is detected.

8. The system of claim 1, wherein the condition is an inactivity condition of the inertial sensor, and the detection module determines the inactivity condition by calculating a change in acceleration, comparing the change in acceleration to a threshold, determining if the change in acceleration is less than the threshold, and if the change in acceleration is less than the threshold, determining if a predetermined period of time has elapsed, wherein the change in acceleration is determined using an acceleration bias captured by the inertial sensor and a measured acceleration produced by the inertial sensor.

9. The system of claim 8, wherein the measured acceleration is produced by the inertial sensor at a predetermined period of time, and the management module modifies the predetermined period of time when inactivity is detected.

10. The system of claim 1, wherein the inertial sensor is formed on a die, and the and sensor circuitry and management circuitry are formed on or in the die.

11. The system of claim 1, wherein the sensor circuitry and management circuitry are formed on or in a first die, and the inertial sensor is formed on or in a second die that is in communication with the first die.

12. The system of claim 1, wherein the inertial sensor includes an accelerometer or a gyroscope.

13. A management system for a MEMS inertial sensor, the system comprising:

a detection module that detects a condition of the inertial sensor; and

a management module that modifies a configuration of the inertial sensor based on the detected condition.

14. The system of claim 13, further comprising:

memory operatively coupled with the management module and the detection module, the memory capable of storing data values produced by the inertial sensor.

15. The system of claim 13, wherein the condition is an activity condition of the inertial sensor, and the detection module determines the activity condition by calculating a change in acceleration and comparing the change in acceleration to a threshold, wherein the change in acceleration is determined using an acceleration bias captured by the inertial sensor and a measured acceleration produced by the inertial sensor.

16. The system of claim 15, wherein the measured acceleration is produced by the inertial sensor at a predetermined period of time, and the management module modifies the predetermined period of time when activity is determined.

17. The system of claim 13, wherein the condition is an inactivity condition of the inertial sensor, and the detection module determines the inactivity condition by calculating a change in acceleration, comparing the change in acceleration to a threshold, determining if the change in acceleration is less than the threshold, and if the change in acceleration is less than the threshold, determining if a predetermined period of time has elapsed, wherein the change in acceleration is determined using an acceleration bias captured by the inertial sensor and a measured acceleration produced by the inertial sensor.

18. The system of claim 17, wherein the measured acceleration is produced by the inertial sensor at a predetermined period of time, and the management module modifies the predetermined period of time when inactivity is determined.

19. A MEMS system comprising:

an inertial sensor having sensor circuitry; and

a management system, implemented with the sensor circuitry, for the inertial sensor, the management system having a detection module that detects a condition of the system and a management module that coordinates the functionality of the inertial sensor and the detection module based on the detected condition.

20. The system of claim 19, wherein the management system further includes memory operatively coupled with the management module and the detection module, the memory capable of storing data values produced by the inertial sensor.