Small Angle Bias Measurement Mechanism For MEMS Instruments

• US 20070245826A1
• Filed: 04/24/2007
• Published: 10/25/2007
• Est. Priority Date: 04/24/2006
• Status: Active Grant

• Current Assignee: Milli Sensor Systems & Actuators, Inc.
• Original Assignee: Milli Sensor Systems & Actuators, Inc.
• Inventors: Cardarelli, Donato
• Granted Patent: US 7,549,334 B2
• Time in Patent Office: Days
• US Class Current: 73/504.120
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01C 21/166 Mechanical, construction or arrangement details of inertial navigation systems
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions

Abstract

A system and method for separating bias instability of MEMS inertial instruments such as gyroscopes or accelerometers from the instrument signal, in which the inertial measurement instrument has an input axis and an output signal, and the bias instability has a frequency. The instrument is oscillated about an oscillation axis that is orthogonal to the input axis, at a frequency that is greater than the bias instability frequency. The instrument output signal is detected, and demodulated with a phase-sensitive detection method referenced to the instrument rotation.

Claims

1. A method for separating bias instability of MEMS inertial instruments such as gyroscopes or accelerometers from the instrument signal, in which the inertial measurement instrument has an input axis and an output signal, and the bias instability has a frequency, the method comprising:

oscillating the instrument about an oscillation axis that is orthogonal to the input axis, at a frequency that is greater than the bias instability frequency;

detecting the instrument output signal; and

demodulating the output signal with a phase-sensitive detection method referenced to the instrument rotation.

2. The method of claim 1 in which the instrument is a MEMS gyroscope.

3. The method of claim 1 in which the instrument is a MEMS accelerometer.

4. The method of claim 1 in which the rotation is about a small angle.

5. A system that separates bias instability of MEMS inertial instruments such as gyroscopes or accelerometers from the instrument signal, in which the inertial measurement instrument has an input axis and an output signal, and the bias instability has a frequency, the system comprising:

a device for oscillating the instrument about an oscillation axis that is orthogonal to the input axis, at a frequency that is greater than the bias instability frequency;

electronics for detecting the instrument output signal; and

electronics for demodulating the output signal with a phase-sensitive detection method referenced to the instrument rotation.

6. The system of claim 5 in which the instrument is a gyroscope.

7. The system of claim 5 in which the instrument is a MEMS accelerometer.

8. The system of claim 5 in which the rotation is about a small angle.

9. The system of claim 5 in which the instrument is a MEMS gyroscope.

10. A system for making inertial measurements about two orthogonal axes that define a plane, using MEMS inertial instruments such as gyroscopes or accelerometers, comprising:

a MEMS inertial measurement instrument that defines an input axis that is parallel to the plane;

a device for oscillating the instrument about an oscillation axis that is orthogonal to the input axis; and

electronics for detecting the instrument output signal.