BALL ROTATIONAL DIRECTION DETECTING SYSTEM

• US 20170261644A1
• Filed: 11/03/2016
• Published: 09/14/2017
• Est. Priority Date: 11/10/2015
• Status: Active Grant

• Current Assignee: Aichi Steel Corporation (Toyota Motor Corporation)
• Original Assignee: Aichi Steel Corporation (Toyota Motor Corporation)
• Inventors: YAMAMOTO, Michiharu
• Granted Patent: US 10,591,637 B2
• Time in Patent Office: Days
• 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: G01V 15/00 Tags attached to, or associated with, an object, in order to enable detection of the object record carriers for use with machines having a detectable tag or marker G06K19/00

Abstract

A ball rotational direction detecting system includes a magnetic sensor that is fixed in a ball, an acceleration sensor, a bearing recording unit that records a moving bearing, a magnetic dip recording unit that records a magnetic dip α of geomagnetism, and a calculating unit. The calculating unit calculates the orientation of the rotation axis and the rotational direction of the ball with respect to a traveling direction F and a gravity direction G of the ball, based on a geomagnetism vector m, an acceleration vector a, the moving bearing, the magnetic dip α, and time variations in the geomagnetism vector m or the acceleration vector a.

Claims

1. A ball rotational direction detecting system that detects an orientation of a rotation axis and a rotational direction of a ball moving in midair with respect to a traveling direction and a gravity direction of the ball, the ball rotational direction detecting system comprising:

a magnetic sensor that detects a geomagnetism vector in a ball coordinate system, which is a three-axis orthogonal coordinate system fixed in the ball;

an acceleration sensor that detects an acceleration vector in the ball coordinate system;

a bearing recording unit that records a moving bearing, the moving bearing being a bearing in which the ball moves;

a magnetic dip recording unit that records a magnetic dip of geomagnetism; and

a calculating unit that calculates an orientation of the rotation axis and a rotational direction of the ball with respect to the traveling direction and the gravity direction based on the geomagnetism vector, the acceleration vector, the moving bearing, the magnetic dip, and a time variation in the geomagnetism vector or the acceleration vector.

2. The ball rotational direction detecting system according to claim 1, wherein

the calculating unit comprises:

a traveling direction calculating unit that calculates the traveling direction in the ball coordinate system based on the acceleration vector detected by the acceleration sensor;

a gravity direction calculating unit that calculates the gravity direction in the ball coordinate system based on the geomagnetism vector detected by the magnetic sensor, the acceleration vector detected by the acceleration sensor, the moving bearing recorded in the bearing recording unit, and the magnetic dip recorded in the magnetic dip recording unit;

a coordinate rotation calculating unit that calculates a rotation axis and a rotational direction of an earth coordinate system in the ball coordinate system based on a time variation in the geomagnetism vector detected by the magnetic sensor or a time variation in the acceleration vector detected by the acceleration sensor; and

a rotational direction calculating unit that calculates the orientation of the rotation axis and the rotational direction of the ball with respect to the traveling direction and the gravity direction based on the traveling direction in the ball coordinate system calculated by the traveling direction calculating unit, the gravity direction in the ball coordinate system calculated by the gravity direction calculating unit, and the rotation axis and the rotational direction of the earth coordinate system in the ball coordinate system calculated by the coordinate rotation calculating unit.

3. The ball rotational direction detecting system according to claim 2, further comprising

a traveling angle recording unit that records a traveling angle β

, the traveling angle β

being an angle formed by the traveling direction and the gravity direction of the ball, wherein

assuming that, with the magnetic dip denoted by a, an angle formed by the geomagnetism vector and the gravity direction is 90°

−

α

, and an angle formed by the acceleration vector and the gravity direction is 180°

−

β

, the gravity direction calculating unit calculates the gravity direction in the ball coordinate system, based on the geomagnetism vector detected by the magnetic sensor, the acceleration vector detected by the acceleration sensor, the magnetic dip, the traveling angle β

, and the moving bearing.

4. The ball rotational direction detecting system according to claim 1, further comprising

a bearing calculating unit that calculates the moving bearing based on the geomagnetism vector detected by the magnetic sensor, in a state where the ball includes on a surface of the ball a first specific region and a second specific region pointing in directions orthogonal to each other, and the ball is brought to a standstill with the first specific region and the second specific region pointing in the moving bearing and a vertically upward direction, respectively, wherein

the moving bearing calculated by the bearing calculating unit is recorded in the bearing recording unit.

5. The ball rotational direction detecting system according to claim 1, further comprising

a magnetic dip calculating unit that calculates the magnetic dip based on the acceleration vector detected by the acceleration sensor and the geomagnetism vector detected by the magnetic sensor, in a state where the ball is brought to a standstill, wherein

the magnetic dip calculated by the magnetic dip calculating unit is recorded in the magnetic dip recording unit.

6. The ball rotational direction detecting system according to claim 1, wherein the calculating unit further comprises a rotational speed calculating unit that further calculates a rotational speed of the earth coordinate system in the ball coordinate system based on the time variation in the geomagnetism vector detected by the magnetic sensor, and calculates a rotational speed of the ball based on the calculated rotational speed of the earth coordinate system in the ball coordinate system.

7. The ball rotational direction detecting system according to claim 1, further comprising:

an impact acceleration sensor that is fixed in the ball and detects an impact acceleration at least in one axis direction, the impact acceleration having a magnitude greater than a magnitude of the acceleration vector detected by the acceleration sensor; and

an end determining unit that determines, based on the acceleration detected by the impact acceleration sensor, a time point at which midair movement of the ball ends.

8. The ball rotational direction detecting system according to claim 7, wherein the impact acceleration sensor has a lower detection sensitivity than the acceleration sensor and has a wider detection range than the acceleration sensor.

9. The ball rotational direction detecting system according to claim 7, wherein the impact acceleration sensor measures the impact acceleration in three axis directions orthogonal to one another.

10. The ball rotational direction detecting system according to claim 7, further comprising a start determining unit that determines, based on the acceleration detected by the impact acceleration sensor, a time point at which the midair movement of the ball starts.

11. The ball rotational direction detecting system according to claim 1, wherein the ball rotational direction detecting system detects using the acceleration sensor an acceleration vector at a time when the ball having been thrown is caught, as a catching-time acceleration vector, and calculates the traveling direction in the ball coordinate system based on the catching-time acceleration vector.

12. The ball rotational direction detecting system according to claim 11, wherein the ball rotational direction detecting system calculates the traveling direction in the ball coordinate system at each time point in a period during which the ball is in midair, based on the catching-time acceleration vector and a large number of geomagnetism vectors that are consecutively obtained while the ball is in midair.

13. The ball rotational direction detecting system according to claim 1, wherein the magnetic sensor is constituted by a magneto-impedance sensor.