BIAS ESTIMATING METHOD, POSTURE ESTIMATING METHOD, BIAS ESTIMATING DEVICE, AND POSTURE ESTIMATING DEVICE

• US 20110320164A1
• Filed: 06/27/2011
• Published: 12/29/2011
• Est. Priority Date: 06/28/2010
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: DING, Yimei, UCHIDA, Shuji
• Granted Patent: US 9,273,967 B2
• Time in Patent Office: Days
• US Class Current: 702/150
• CPC Class Codes: G01C 21/185 for gravity
• CPC Class Codes: G01C 21/188 for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems
• CPC Class Codes: G01P 21/00 Testing or calibrating of apparatus or devices covered by the preceding groups

Abstract

A bias estimating method includes: calculating a virtual posture angle which is a posture angle with a bias which is assumed to be zero by the use of detection values of a plurality of axes in a calibration posture where one axis of a multi-axis acceleration sensor is parallel to the vertical direction; and estimating a bias value contained in the detection value of the axis using the detection value of the axis and the virtual posture angle.

Claims

1. A bias estimating method comprising:

calculating a virtual posture angle which is a posture angle with a bias which is assumed to be zero through the use of detection values of a plurality of axes in a calibration posture where one axis of a multi-axis acceleration sensor is parallel to the vertical direction; and

estimating a bias value contained in the detection value of the axis using the detection value of the axis and the virtual posture angle.

2. The bias estimating method according to claim 1, further comprising calculating an estimation error of the bias value using the virtual posture angle and error variance of the bias value.

3. The bias estimating method according to claim 2, wherein the estimation error of the bias value contained in the detection value of the axis can be approximated using the virtual posture angle and an error in the virtual posture angle, and

wherein the calculating of the estimation error of the bias value includes calculating the estimation error of the bias value contained in the detection value of the axis on the basis of the fact that the error in the virtual posture angle can be estimated using the error variance of the bias value.

4. The bias estimating method according to claim 1, wherein the acceleration sensor is at least a temperature-compensated sensor.

5. The bias estimating method according to claim 1, further comprising performing at least a temperature compensating operation to compensate for the output of the acceleration sensor and to acquire the detection value.

6. A posture estimating method of estimating a posture of the acceleration sensor using the bias value estimated by the bias estimating method according to claim 1 and the detection values of the axes of the acceleration sensor.

7. A bias estimating device comprising:

a virtual posture angle calculating unit that calculates a virtual posture angle which is a posture angle with a bias which is assumed to be zero by the use of detection values of a plurality of axes in a calibration posture where one axis of a multi-axis acceleration sensor is parallel to the vertical direction; and

a bias estimating unit that estimates a bias value contained in the detection value of the axis using the detection value of the axis and the virtual posture angle.

8. A posture estimating device comprising:

a multi-axis acceleration sensor;

the bias estimating device according to claim 7 that estimates the bias value contained in the detection values of the plurality of axes of the acceleration sensor; and

a posture estimating unit that estimates a posture of the acceleration sensor using the bias value estimated by the bias estimating device and the detection values of the plurality of axes of the acceleration sensor.