Device and method for calculating absolute amount of displacement, and method for same

• US 9,841,947 B2
• Filed: 06/28/2012
• Issued: 12/12/2017
• Est. Priority Date: 07/12/2011
• Status: Active Grant

• Current Assignee: Oriental Motor Company Limited
• Original Assignee: Oriental Motor Company Limited
• Inventors: Houda, Akihiko, Furuta, Masaharu
• Primary Examiner(s): Kundu, Sujoy
• Assistant Examiner(s): Anderson, Lynne
• Application Number:
  US14/232,051
• Publication Number:
  US 20140172932A1
• Time in Patent Office: 1,993 Days
• CPC Class Codes: G01D 2205/26 Details of encoders or position sensors specially adapted to detect rotation beyond a full turn of 360°, e.g. multi-rotation
• CPC Class Codes: G01D 5/2454 Encoders incorporating incremental and absolute signals
• CPC Class Codes: G01D 5/2497 Absolute encoders G01D5/2454 takes precedence
• CPC Class Codes: G01D 5/34746 Linear encoders
• CPC Class Codes: G06F 7/483 Computations with numbers represented by a non-linear combination of denominational numbers, e.g. rational numbers, logarithmic number system or floating-point numbers G06F7/4806, G06F7/4824, G06F7/49, G06F7/491, G06F7/544 take precedence

Abstract

Some embodiments include an absolute displacement detection device configured to calculate, from a plurality of displacement detection signals provided by a plurality of displacement detection mechanisms that detect displacement amounts, an absolute periodic signal having an absolute periodic signal period larger than displacement detection signal periods of the plurality of the displacement detection signals. Other embodiments of related devices and methods are also disclosed.

Claims

1. A system for determining an absolute amount of displacement of a moving body, the system comprising:

a displacement detection mechanism configured to detect displacement amounts, the displacement detection mechanism comprising multiple sensors configured to detect the displacement amounts and a transmission mechanism comprising a main shaft configured to move rotationally, a first countershaft configured to receive a rotation of the main shaft transmitted at a first transmission gear ratio, and a second countershaft configured to receive the rotation of the main shaft transmitted at a second transmission gear ratio; and

an absolute displacement detection device configured to receive a plurality of displacement detections signals from the multiple sensors and configured to calculate an absolute periodic signal based on the plurality of displacement detection signals provided by the multiple sensors;

wherein;

the main shaft is coupled to a shaft of a rotary drive source;

the moving body comprises the shaft of the rotary drive source;

the multiple sensors comprise;

a first angle sensor configured to detect a first amount of displacement of the main shaft;

a second angle sensor configured to detect a second amount of displacement of the first countershaft; and

a third angle sensor configured to detect a third amount of displacement of the second countershaft;

the main shaft is equipped with the first angle sensor;

the first countershaft is equipped with the second angle sensor;

the second countershaft is equipped with the third angle sensor;

the displacement amounts comprise the first amount of the displacement of the main shaft, the second amount of the displacement of the first countershaft, and the third amount of the displacement of the second countershaft;

the absolute periodic signal has an absolute periodic signal period larger than displacement detection signal periods of the plurality of the displacement detection signals; and

the absolute displacement detection device comprises;

a first computation module configured to run at one or more processors and to generate, from the plurality of the displacement detection signals, a first periodic signal having a first period and a second periodic signal having a second period different than the first period, the first periodic signal and the second periodic signal being digitized with a common base unit amount and being changed in synchronization;

a second computation module configured to run at the one or more processors and to calculate a first residue by dividing (i) a difference between a value resulting from multiplying the first periodic signal by a first coefficient and a value resulting from multiplying the second periodic signal by a second coefficient by (ii) a common multiple of the first period and the second period, the first coefficient being a value resulting from dividing the common multiple by the first period, and the second coefficient being a value resulting from dividing the common multiple by the second period;

a third computation module configured to run at the one or more processors and to calculate a second residue by dividing the first residue by a difference between the first coefficient and the second coefficient; and

a fourth computation module configured to run at the one or more processors and to calculate a value resulting from adding to the first residue, a value resulting from multiplying the second residue by the common multiple.

2. The system of claim 1, wherein the multiple sensors further comprise a displacement sensor configured to detect a fourth amount of displacement of a movable body that moves linearly.

3. The system of claim 2, wherein the displacement sensor detects the fourth amount of the displacement of the movable body and provides a displacement detection signal to the absolute displacement detection device.

4. The system of claim 1, wherein the multiple sensors further comprise multiple displacement sensors configured to detect multiple amounts of displacement of multiple moving bodies that move linearly.

5. The system of claim 1, wherein the fourth computation module is further configured to calculate the absolute periodic signal by dividing (a) the value resulting from adding to the first residue, the value resulting from multiplying the second residue by the common multiple by (b) the difference between the first coefficient and the second coefficient.

6. The system of claim 5, wherein the absolute displacement detection device is further configured to determine an absolute rotation angle of the main shaft by multiplying the common base unit amount by the absolute periodic signal and further adding an angle of rotation of the main shaft thereto.

7. The system of claim 6, wherein the common multiple is a least common multiple.

8. The system of claim 6, wherein the common multiple is a least common multiple.

9. The system of claim 1, wherein the absolute displacement detection device is further configured to determine an absolute rotation angle of the main shaft by multiplying the common base unit amount by the absolute periodic signal and further adding an angle of rotation of the main shaft thereto.

10. The system of claim 1, wherein the common multiple is a least common multiple.

11. The system of claim 1, wherein:

the rotary drive source comprises a motor.

12. A method for determining an absolute amount of displacement of a moving body, the method comprising:

calculating an absolute periodic signal based on a plurality of displacement detection signals provided by multiple sensors of a displacement detection mechanism configured to detect displacement amounts, wherein the multiple sensors are configured to detect the displacement amounts, the displacement detection mechanism further comprises a transmission mechanism comprising a main shaft transmitted at a first transmission gear ratio, and a second countershaft configured to receive the rotation of the main shaft transmitted at a second transmission gear ratio, the main shaft is coupled to a shaft of a rotary drive source, the moving body comprises the shaft of the rotary drive source, the multiple sensors comprise (i) a first angle sensor configured to detect a first amount of displacement of the main shaft, (ii) a second angle sensor configured to detect a second amount of displacement of the first countershaft, and (iii) a third angle sensor configured to detect a third amount of displacement of the second countershaft, the main shaft is equipped with the first angle sensor, the first countershaft is equipped with the second angle sensor, the second countershaft is equipped with the third angle sensor, the displacement amounts comprise the first amount of the displacement of the main shaft, the second amount of the displacement of the first countershaft, and the third amount of the displacement of the second countershaft, the absolute periodic signal has an absolute periodic signal period larger than displacement detection signal periods of the plurality of the displacement detection signals, and calculating the absolute periodic signal based on the plurality of displacement detection signals provided by the multiple sensors of the displacement detection mechanism configured to detect the displacement amounts comprises;

generating, from the plurality of displacement detection signals, a first periodic signal having a first period and a second periodic signal having a second period different than the first period, the first periodic signal and the second periodic signal being digitized with a common base unit amount and being changed in synchronization;

calculating a first residue by dividing (i) a difference between a value resulting from multiplying the first periodic signal by a first coefficient and a value resulting from multiplying the second periodic signal by a second coefficient by (ii) a common multiple of the first period and the second period, the first coefficient being a value resulting from dividing the common multiple by the first period, and the second coefficient being a value resulting from dividing the common multiple by the second period;

calculating a second residue by dividing the first residue by a difference between the first coefficient and the second coefficient; and

calculating a value resulting from adding to the first residue, a value resulting from multiplying the second residue by the common multiple.

13. The method of claim 12, further comprising detecting the displacement amount with the multiple sensors.

14. The method of claim 12, further comprising detecting, with a displacement sensor of the multiple sensors, a fourth amount of displacement of a movable body that moves linearly.

15. The method of claim 12, further comprising detecting, with multiple displacement sensors of the multiple sensors, multiple amounts of displacement of multiple moving bodies that move linearly.

16. The method of claim 12, wherein:

calculating the absolute periodic signal based on the plurality of displacement detection signals provided by the multiple sensors of the displacement detection mechanisms configured to detect the displacement amounts further comprises;

calculating the absolute periodic signal by dividing (a) the value resulting from adding to the first residue, the value resulting from multiplying the second residue by the common multiple by (b) the difference between the first coefficient and the second coefficient.

17. The method of claim 16, further comprising:

determining an absolute rotation angle of the main shaft by multiplying the common base unit amount by the absolute period signal and further adding an angle of rotation of the main shaft thereto.

18. The method of claim 16, wherein:

the rotary drive source comprises a motor.

19. The method of claim 12, wherein the common multiple is a least common multiple.

20. The method of claim 12, further comprising:

determining an absolute rotation angle of the main shaft by multiplying the common base unit amount by the absolute period signal and further adding an angle of rotation of the main shaft thereto.