Attitude angle processor and attitude angle processing method

• US 20060217921A1
• Filed: 01/14/2004
• Published: 09/28/2006
• Est. Priority Date: 01/15/2003
• Status: Active Grant

• Current Assignee: National Institute of Advanced Industrial Science and Technology (Government of Japan)
• Original Assignee: National Institute of Advanced Industrial Science and Technology (Government of Japan)
• Inventors: Kurata, Takeshi, Kourogi, Masakatsu, Okuma, Takashi, Kato, Takakazu, Sakata, Nobuchika
• Granted Patent: US 7,222,045 B2
• Time in Patent Office: Days
• US Class Current: 702/150
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses

Abstract

A posture angle processing apparatus that can obtain correct information for a posture angle comprises: a magnetic sensor, a gravitational acceleration sensor, a position information acquisition device, for obtaining the absolute location of a current point, and a dip angle database device wherein a correlation of the absolute location and a geomagnetic dip angle at the corresponding point is stored. Based on the absolute location of the current point, a dip angle estimation and determination device reads, from the dip angle database device, the geomagnetic dip angle at the current point, employs the magnetic vector detected by the magnetic sensor and the gravitational acceleration vector detected by the gravitational acceleration sensor to calculate an angle formed by a horizontal plane and the magnetic vector, compares the angle formed by the magnetic vector and the horizontal plane with the geomagnetic dip angle of the current point, and, when an error between the angle and the geomagnetic dip angle is within a predetermined range, outputs a true signal indicating that the magnetic vector detected by the magnetic sensor is reliable as a geomagnetic vector, or in other cases, outputs a false signal indicating that the current magnetic vector is not reliable.

Claims

1. A posture angle processing apparatus comprising:

a magnetic sensor for detecting a magnetic vector;

a gravitational acceleration sensor for detecting a gravitational acceleration vector;

a position information acquisition device for obtaining an absolute location for a current point;

a dip angle database device for storing a correlation of the absolute location and a geomagnetic dip angle at a corresponding point; and

a dip angle estimation and determination device, for, based on the absolute location of the current point received from the position information acquisition device, reading a geomagnetic dip angle for the current point from the dip angle database device, for employing the magnetic vector detected by the magnetic sensor and the gravitational acceleration vector detected by the gravitational acceleration sensor to calculate an angle formed by a horizontal plane and the magnetic vector, for comparing the angle formed by the magnetic vector and the horizontal plane with the geomagnetic dip angle for the current point, and for, when an error between the angle and the geomagnetic dip angle is within a predetermined range, outputting a true signal indicating that the magnetic vector detected by the magnetic sensor is reliable as a geomagnetic vector, and in other cases, outputting a false signal indicating that the current magnetic vector is not reliable.

2. The posture angle processing apparatus according to claim 1, further comprising:

a movement detection device for detecting the presence or absence of a moving state; and

a signal output device, for, when the movement detection device is detecting a moving state over a predesignated moving distance or over a predesignated moving period of time, and when the dip angle estimation and determination device is continuously outputting a true signal, outputting a true signal indicating that the current magnetic vector detected by the magnetic sensor is reliable as a geomagnetic vector, and in other cases, outputting a false signal indicating that the current magnetic vector is not reliable.

3. The posture angle processing apparatus according to claim 1, further comprising:

an absolute posture angle estimation device, for, when the dip angle estimation and determination device is outputting a true signal, estimating and outputting an absolute posture angle based on the magnetic vector detected by the magnetic sensor and the gravitational acceleration vector detected by the gravitational acceleration sensor.

4. The posture angle processing apparatus according to claim 2, wherein

the movement detection device includes a walking detection device for detecting a person is walking to determine the presence or absence of a moving state.

5. The posture angle processing apparatus according to claim 2, further comprising;

an absolute posture angle estimation device, for, when the dip angle estimation and determination device is outputting a true signal, estimating and outputting an absolute posture angle based on the magnetic vector detected by the magnetic sensor and the gravitational acceleration vector detected by the gravitational acceleration sensor.

6. The posture angle processing apparatus according to claim 4, wherein

the walking detection device includes:

an acceleration sensor for detecting the walking of the person; and

the walking detection device detects a vertical direction in accordance with the gravitational acceleration vector detected by the gravitational acceleration sensor, detects a typical pattern created by the walking of the person, in accordance with a component in the vertical direction included in the acceleration vector that is detected by the acceleration sensor, detects a typical pattern created by the walking of the person, in accordance with a component in the direction of a plane perpendicular to the vertical direction of the acceleration vector, and employs the detection results of these patterns to detect the walking of the person.

7. The posture angle processing apparatus according to claim 3, further comprising:

an angular velocity sensor, wherein

when the dip angle estimation and determination device is outputting a true signal, the absolute posture angle estimation device outputs, as a current absolute posture angle, the absolute posture angle output by the absolute posture angle estimation device, and

when the dip angle estimation and determination device is outputting a false signal, the absolute posture angle estimation device employs, as a reference, the last absolute posture angle that is output by the absolute posture estimation device, estimates the current absolute posture angle by adding an angular velocity vector measured by the angular velocity sensor, and outputs the results.

8. The posture angle processing apparatus according to claim 5, further comprising:

an angular velocity sensor, wherein

when the dip angle estimation and determination device is outputting a true signal, the absolute posture angle estimation device outputs, as a current absolute posture angle, the absolute posture angle output by the absolute posture angle estimation device, and

when the dip angle estimation and determination device is outputting a false signal, the absolute posture angle estimation device employs, as a reference, the last absolute posture angle that is output by the absolute posture estimation device, estimates the current absolute posture angle by adding an angular velocity vector measured by the angular velocity sensor, and outputs the results.

9. A posture angle processing method by which a posture angle process is performed by a posture angle processing apparatus that includes:

a magnetic sensor for detecting a magnetic vector, a gravitational acceleration sensor for detecting a gravitational acceleration vector, a position information acquisition device for obtaining an absolute location for a current point, a dip angle database device for storing a correlation of the absolute location and a geomagnetic dip angle at a corresponding point, and a data processing device,

the posture angle processing method comprising the steps of;

based on an absolute location of a current point received from a position information acquisition device that obtains an absolute location of a current point, reading a geomagnetic dip angle for the current point from a dip angle database device wherein a correlation of the absolute location and the geomagnetic dip angle at the corresponding point is stored;

employing a magnetic vector detected by a magnetic sensor and a gravitational acceleration vector detected by a gravitational acceleration sensor to calculate an angle formed by a horizontal plane and the magnetic vector;

comparing the angle formed by the magnetic vector and the horizontal plane with the geomagnetic dip angle for the current point, and

when an error between the angle and the geomagnetic dip angle is within a predetermined range, outputting a true signal indicating that the magnetic vector detected by the magnetic sensor is reliable as a geomagnetic vector, and in other cases, outputting a false signal indicating that the current magnetic vector is not reliable.

10. The posture angle processing method according to claim 9, wherein

a movement detection device that detects the presence or absence of a moving state is detecting a moving state over a predesignated moving distance or over a predesignated moving period of time;

and

the angle formed by the magnetic vector is compared with the horizontal plane with the geomagnetic dip angle for the current point, and

when an error between the angle and the geomagnetic dip angle is within a predetermined range, and when a true signal indicating that the magnetic vector detected by the magnetic sensor is reliable as a geomagnetic vector is continuously output, a true signal indicating that the current magnetic vector detected by the magnetic sensor is reliable as a geomagnetic vector is output, and in other cases, a false signal indicating that the current magnetic vector is not reliable is output.

11. The posture angle processing method according to claim 9, wherein

the angle formed by the magnetic vector is compared with the horizontal plane with the geomagnetic dip angle for the current point, and

when an error between the angle and the geomagnetic dip angle is within a predetermined range, and when a true signal indicating that the magnetic vector detected by the magnetic sensor is reliable as a geomagnetic vector is continuously output, an absolute posture angle is estimated and output based on the magnetic vector detected by the magnetic sensor and the gravitational acceleration vector detected by the gravitational acceleration sensor.

12. The posture angle processing method according to claim 10, wherein

the movement detection device detects a person is walking to determine the presence or absence of a moving state.

13. The posture angle processing method according to claim 10, wherein

the angle formed by the magnetic vector is compared with the horizontal plane with the geomagnetic dip angle for the current point, and

when an error between the angle and the geomagnetic dip angle is within a predetermined range, and when a true signal indicating that the magnetic vector detected by the magnetic sensor is reliable as a geomagnetic vector is continuously output, an absolute posture angle is calculated and output based on the magnetic vector detected by the magnetic sensor and the gravitational acceleration vector detected by the gravitational acceleration sensor.

14. The posture angle processing method according to claim 12, wherein

a vertical direction is detected in accordance with the gravitational acceleration vector detected by the gravitational acceleration sensor;

a typical pattern created by the walking of the person is detected, in accordance with a component in the vertical direction included in an acceleration vector that is detected by an acceleration sensor that detects walking of a person;

a typical pattern created by the walking of the person is detected, in accordance with a component in the direction of a plane perpendicular to the vertical direction of the acceleration vector; and

the detection results of the patterns are employed to detect the walking of the person.

15. The posture angle processing method according to claim 11, wherein

the angle formed by the magnetic vector is compared with the horizontal plane with the geomagnetic dip angle for the current point, and

when an error between the angle and the geomagnetic dip angle is within a predetermined range, and when a true signal indicating that the magnetic vector detected by the magnetic sensor is reliable as a geomagnetic vector is continuously output, an absolute posture angle is output as a current absolute posture angle based on the magnetic vector detected by the magnetic sensor and the gravitational acceleration vector detected by the gravitational acceleration sensor;

and when the true signal is not output, the last absolute posture angle that is output is employed as a reference to estimate the current absolute posture angle by adding an angular velocity vector measured by the angular velocity sensor, and the results are output.

16. The posture angle processing method according to claim 13, wherein

the angle formed by the magnetic vector is compared with the horizontal plane with the geomagnetic dip angle for the current point, and

when an error between the angle and the geomagnetic dip angle is within a predetermined range, and when a true signal indicating that the magnetic vector detected by the magnetic sensor is reliable as a geomagnetic vector is continuously output, an absolute posture angle is output as a current absolute posture angle based on the magnetic vector detected by the magnetic sensor and the gravitational acceleration vector detected by the gravitational acceleration sensor;

and when the true signal is not output, the last absolute posture angle that is output is employed as a reference to estimate the current absolute posture angle by adding an angular velocity vector measured by the angular velocity sensor, and the results are output.