Ball rotational direction detecting system

• US 10,591,637 B2
• Filed: 11/03/2016
• Issued: 03/17/2020
• 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
• Primary Examiner(s): Bloss, Stephanie E
• Application Number:
  US15/342,409
• Publication Number:
  US 20170261644A1
• Time in Patent Office: 1,230 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; and

circuitry configured to;

record a moving bearing, the moving bearing functioning as compass bearings and being a bearing in which the ball moves;

record a magnetic dip of geomagnetism;

calculate the orientation of the rotation axis and the rotational direction of the ball with respect to the traveling direction and the gravity direction by using all of

     1) the geomagnetism vector,

     2) the acceleration vector,

     3) the moving bearing,

     4) the magnetic dip, and

     5) one of a first time variation in the geomagnetism vector and a second time variation in the acceleration vector;

calculate two vectors to be candidates of the gravity direction in the ball coordinate system by using the geomagnetism vector detected by the magnetic sensor, the acceleration vector detected by the acceleration sensor, and the magnetic dip; and

specify one of the two vectors thus calculated as a vector in the gravity direction in the ball coordinate system by using the moving bearing,

wherein the circuitry specifies by selecting one of the two vectors closer to a vector product (m×

a) of a magnetic vector m and the acceleration vector a as the vector in the gravity direction in the ball coordinate system in a first case where the moving bearing includes a westward vector component, and

the circuitry specifies by selecting another of the two vectors closer to another vector product (a×

m) of the acceleration vector a and the magnetic vector m as the vector in the gravity direction in the ball coordinate system in a second case where the moving bearing includes an eastward vector component.

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

the circuitry is configured to:

calculate the traveling direction in the ball coordinate system by using the acceleration vector detected by the acceleration sensor;

calculate another rotation axis and another rotational direction of an earth coordinate system in the ball coordinate system by using the first time variation in the geomagnetism vector detected by the magnetic sensor or the second time variation in the acceleration vector detected by the acceleration sensor; and

calculate the orientation of the rotation axis and the rotational direction of the ball with respect to the traveling direction and the gravity direction by using the traveling direction in the ball coordinate system, the gravity direction in the ball coordinate system, and the other rotation axis and the other rotational direction of the earth coordinate system in the ball coordinate system.

3. The ball rotational direction detecting system according to claim 1, wherein the circuitry is further configured to:

record 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 α

, 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 circuitry calculates the gravity direction in the ball coordinate system, by using 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, wherein the circuitry is further configured to:

calculate the moving bearing by using 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 is recorded in the circuitry.

5. The ball rotational direction detecting system according to claim 1, wherein the circuitry is further configured to:

calculate the magnetic dip by using 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 is recorded in the circuitry.

6. The ball rotational direction detecting system according to claim 1, wherein the circuitry is further configured to calculate a first rotational speed of an earth coordinate system in the ball coordinate system by using the first time variation in the geomagnetism vector detected by the magnetic sensor, and to calculate a second rotational speed of the ball by using 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,

wherein the circuitry is further configured to determine by using the impact acceleration detected by the impact acceleration sensor, a time point at which a midair movement of the ball stops.

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, wherein the circuitry is further configured to determine, by using the impact 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 an acceleration vector at a time when the ball having been thrown is caught, is detected as a catching-time acceleration vector, and the traveling direction in the ball coordinate system is calculated by using the catching-time acceleration vector.

12. The ball rotational direction detecting system according to claim 11, wherein the traveling direction in the ball coordinate system at each time point in a period during which the ball is in midair, is calculated by using the catching-time acceleration vector and a plurality 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 includes at least one sensor element with an amorphous wire.

14. The ball rotational direction detecting system according to claim 13, wherein the magnetic sensor includes three of the at least one sensor element, the three of the at least one sensor element disposed such that the respective amorphous wires are orthogonal to one another.

15. The ball rotational direction detecting system according to claim 14, wherein each of the three of the at least one sensor element includes a base and a detecting coil, an amorphous wire fixed to the base, the detecting coil wound around the amorphous wire.

16. The ball rotational direction detecting system according to claim 15, wherein the base is formed of a non-magnetic substance.

17. The ball rotational direction detecting system according to claim 1, wherein the circuitry specifies so as to select arbitrarily one of the two vectors as the vector in the gravity direction in the ball coordinate system in a third case where the moving bearing does not include the westward vector component and the eastward vector component.