Multi-turn Measuring System

Abstract

To provide a multi-turn measurement system capable of measuring rotation over multiple turns.SOLUTION: A multi-turn measurement system is provided, comprising a plurality of gears 30, a plurality of pinions 20 engaging the plurality of gears 30, a plurality of magnets 40, each disposed on one of the plurality of gears 30, and a plurality of magnetic field sensors. Rotation of the pinions 20 about a center axis drives rotation of the plurality of gears 30. Each of the magnets 40 has a magnetic field that changes based on an angular position of one of the plurality of gears 30. Each of the magnetic field sensors is positioned to sense the magnetic field of one of the plurality of magnets 40.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a measurement system, and more particularly to a measurement system capable of measuring rotation over multiple turns. [Background technology]

[0002] To measure the rotation of a shaft over multiple turns, existing measurement systems are used that indicate the angular position of the shaft at a given time and the number of revolutions the shaft has undergone. Such measurement systems are used, for example, in cable-actuated position sensors, where a cable is wound around a shaft and the shaft rotates as the cable is pulled and unwound from the shaft. In various applications, the angular position of the shaft and the number of revolutions of the shaft indicate the length of cable that is unwound to measure the linear position. Summary of the Invention [Problem to be solved by the invention]

[0003] The angular position of the shaft and the number of revolutions of the shaft in such measurement systems are typically measured by a potentiometer, where the rotation of the shaft linearly changes the output voltage of the potentiometer. However, potentiometers with high levels of precision are very expensive. Furthermore, potentiometers are very prone to mechanical failures due to manufacturing uncertainties, which leads to electrical problems and corresponding inaccuracies in measurements. [Means for solving the problem]

[0004] The multi-turn measurement system includes a plurality of gears, a plurality of pinions engaged with the plurality of gears, a plurality of magnets each disposed on one of the plurality of gears, and a plurality of magnetic field sensors. Rotation of the pinion about a central axis drives rotation of the plurality of gears. Each of the magnets has a magnetic field that varies based on an angular position of one of the plurality of gears. Each of the magnetic field sensors is positioned to sense the magnetic field of one of the plurality of magnets.

[0005] The invention will now be described, by way of example only, with reference to the accompanying drawings in which: [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective view of a multi-turn measurement system according to one embodiment. [Diagram 2] FIG. 2 is an exploded perspective view of the multi-turn measurement system, with the sensor board and electromagnetic shield of the multi-turn measurement system shown as transparent. [Diagram 3] FIG. 2 is a perspective view of a shaft, pinions, gears, and magnets of a multi-turn measurement system. [Figure 4] FIG. 13 is a detailed side view of the pinion, gears, magnets, sensor board, and a portion of the electromagnetic shield of the multi-turn measurement system. [Diagram 5] FIG. 2 is a perspective view of a sensor board. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Exemplary embodiments of the present disclosure are described in detail below with reference to the accompanying drawings in which like reference numerals refer to like elements. However, the present disclosure can be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure fully conveys the concept of the present disclosure to those skilled in the art. Furthermore, in the following detailed description, for the purpose of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, it is apparent that one or more embodiments can be implemented without these specific details.

[0008] A multi-turn measurement system according to one embodiment is shown in Figures 1 and 2. As shown in Figures 1 and 2, the measurement system includes a shaft 10, a plurality of pinions 20 disposed on the shaft 10 and rotatable together with the shaft 10, a plurality of gears 30 engaged with the plurality of pinions 20 and driven by the rotation of the pinions 20, a plurality of magnets 40 disposed on the gears 30, and a sensor board 50 disposed adjacent to the gears 30 and the magnets 40.

[0009] The shaft 10 extends along a central axis C between a first end 12 and a second end 14, as shown in Figures 2 and 3. In the embodiment shown in Figures 1 and 2, the first end 12 is a free end and the second end 14 is rotatably fixed to a spool 16 that extends around a portion of the shaft 10. In this embodiment, a cable, string, or any other elongate member known to those skilled in the art may be wound around the spool 16, and unwinding the elongate member imparts a rotation to the spool 16, which imparts a corresponding rotation to the shaft 10. In another embodiment, the shaft 10 is not secured to the spool 16. In this embodiment, rotation can be imparted to the shaft 10 by various other elements known to those skilled in the art.

[0010] The multiple pinions 20 include a first pinion 22 and a second pinion 24, as shown in FIGS. 2-4. The first pinion 22 is a circular member having a plurality of first pinion teeth 22t evenly arranged around the outer periphery of the first pinion 22. The second pinion 24 is a circular member having a plurality of second pinion teeth 24t evenly arranged around the outer periphery of the second pinion 24. The number of the first pinion teeth 22t is different from the number of the second pinion teeth 24t, and the diameter of the first pinion 22 is different from the diameter of the second pinion 24. In the illustrated embodiment, the number of the first pinion teeth 22t is less than the number of the second pinion teeth 24t, and the diameter of the first pinion 22 is smaller than the diameter of the second pinion 24. In the embodiment shown, the number of first pinion teeth 22t is 16 and the number of second pinion teeth 24t is 18. The number and diameter of the individual associated teeth of the first pinion 22 and second pinion 24 may vary in other embodiments.

[0011] The pinion 20 is disposed at the first end 12 of the shaft 10, as shown in Figure 3. The first pinion 22 and the second pinion 24 are disposed at different locations along the central axis C. In the embodiment shown, the second pinion 24 is disposed closer to the second end 14 of the shaft 10 than the first pinion 22. The pinion 20 is rotatably fixed to the shaft 10 and simultaneously rotates about the central axis C in response to the rotation of the shaft 10.

[0012] The multiple gears 30 include a first gear 32, a second gear 34, and a third gear 38, as shown in Figs. 2 and 3. The first gear 32 is a circular member having a first gear diameter direction 32D and a plurality of first gear teeth 32t evenly distributed around the outer periphery of the first gear 32, as shown in Fig. 3. The first gear 32 rotates around a first rotation axis 32B. The second gear 34 is a circular member having a second gear diameter direction 34D and a plurality of second gear teeth 34t evenly distributed around the outer periphery of the second gear 34. The second gear 34 rotates around a second rotation axis 34B. The second gear 34 has an extension 36 disposed in the center of the second gear 34 and protruding from the second gear 34 along the second rotation axis 34B, as shown in Fig. 3. The third gear 38 is a circular member having a third gear diameter direction 38D and a plurality of third gear teeth 38t evenly distributed around the outer periphery of the third gear 38. The third gear 38 rotates about a third rotation axis 38B. The first rotation axis 32B, the second rotation axis 34B, and the third rotation axis 38B are parallel to each other and to the central axis C.

[0013] The number of first gear teeth 32t is different from the number of second gear teeth 34t, and the diameter of the first gear 32 is different from the diameter of the second gear 34. The number of second gear teeth 34t is equal to the number of third gear teeth 38t, and the diameter of the second gear 34 is equal to the diameter of the third gear 38. In the embodiment shown, the number of first gear teeth 32t is less than the number of second gear teeth 34t and the third gear teeth 38t, and the diameter of the first gear 32 is less than the diameters of the second gear 34 and the third gear 38. In the embodiment shown, the number of first gear teeth 32t is 42, and the number of second gear teeth 32t and the third gear teeth 38t is 48. In other embodiments, the individual and relative numbers of teeth and diameters of the first gear 32, second gear 34, and third gear 38 may be different.

[0014] 3, the first gear 32 and the third gear 38 are disposed at a different location from the second gear 34 along the central axis C, with the first gear 32 and the third gear 38 positioned to engage the first pinion 22 and the second gear 34 positioned to engage the second pinion 24. The first gear 32 and the third gear 38 are aligned at the same location along the central axis C. Rotation of the first pinion 22 drives rotation of the first gear 32 about the first axis of rotation 32B and the third gear 38 about the third axis of rotation 38B, and rotation of the second pinion 24 drives rotation of the second gear 34 about the second axis of rotation 34B.

[0015] The magnets 40 include a first magnet 42 disposed on the first gear 32, a second magnet 44 disposed on the second gear 34, and a third magnet 46 disposed on the third gear 38, as shown in Figs. 2 and 3. The second magnet 44 is disposed on the extension 36 of the second gear 34 so as to be flush with the first magnet 42 and the third magnet 46, as shown in Fig. 3. Each of the magnets 40 is disposed in the center on the rotation axis 32B, 34B, 38B of the corresponding gear 30. The magnetization directions 42M, 44M, 46M of each of the magnets 40, i.e., the directions extending between the N pole and the S pole of the magnet 40, extend in the diametric directions 32D, 34D, 38D of the corresponding gear 30. Each of the magnets 40 rotates together with the gear 30.

[0016] The sensor board 50 shown in Figures 1, 2, 4, and 5 is a printed circuit board having a first side 52 and an opposing second side 54. A plurality of magnetic field sensors 56 are disposed on the first side 52 of the sensor board 50. The number of magnetic field sensors 56 corresponds to the number of magnets 40 disposed on the gear 30, and in the embodiment shown, there are three magnetic field sensors 56. In one embodiment, each of the magnetic field sensors 56 is an anisotropic magnetoresistive (AMR) sensor.

[0017] As shown in FIG. 1 , the integrated circuit 58 is disposed on the second side 54 of the sensor board 50. The integrated circuit 58 is electrically connected to each of the magnetic field sensors 56 through wiring on the sensor board 50 and can receive electrical signals from each of the magnetic field sensors 56. The integrated circuit 58 includes a processor and a memory connected to the processor. The memory is a non-transitory computer-readable medium that stores algorithms executable by the processor to generate output signals based on input signals from the magnetic field sensors 56, as described in more detail below. In the embodiment shown, the integrated circuit 58 is a commercially available application specific integrated circuit ("ASIC") known as iC-MNF manufactured by iC Haus.

[0018] 1, 2 and 4, the sensor board 50 is positioned adjacent to the gear 30 with a first side 52 of the sensor board 50 facing the gear 30 and the magnets 40. Each of the magnetic field sensors 56 is aligned with and centrally located with one of the magnets 40 along the axis of rotation 32B, 34B, 38B of the corresponding magnet 40.

[0019] In the embodiment shown in Figures 2 and 4, the multi-turn measurement system includes an electromagnetic shield 60. The electromagnetic shield 60 is formed from a sheet of material, as shown in Figure 2, and includes a number of sensor passages 62 extending through the electromagnetic shield 60. In one embodiment, the sensor passages 62 are punched into the sheet of material. In the embodiment shown, the electromagnetic shield 60 is formed from a steel material. In other embodiments, the electromagnetic shield 60 may be formed from a ferrous material or any other material capable of providing electromagnetic shielding as known to those skilled in the art.

[0020] 2 and 4, the electromagnetic shield 60 is disposed on the first surface 52 of the sensor board 50 and is disposed between the gear 30 and the sensor board 50. Each of the magnetic field sensors 56 is disposed in one of the sensor passages 62 of the electromagnetic shield 60 and is surrounded by the electromagnetic shield 60. As shown in FIG. 4, each of the magnetic field sensors 56 protrudes from the first surface 52 of the sensor board 50 by an amount approximately equal to the thickness of the electromagnetic shield 60.

[0021] 1 and 2, the multi-turn measurement system includes a communication board 70. The communication board 70 is a printed circuit board electrically connected to the sensor board 50 and adapted to receive an output signal from the integrated circuit 58. The communication board 70 has one of several different types of electrical connection ports and / or one of several different types of signal formats embodied in several electrical components installed on the communication board 70 as known to those skilled in the art.

[0022] The multi-turn measurement system, in the embodiment shown in Figures 1 and 2, includes a housing 80 in which the shaft 10, pinion 20, gear 30, magnet 40, sensor board 50, electromagnetic shield 60, and communication board 70 are assembled. As shown in Figure 2, the housing 80 has a base 82, a shaft passage 84 extending through the center of the base 82, and a sidewall 86 extending from the base 82 about a central axis C. The base 82 and the sidewall 86 define a component receiving space 88.

[0023] As shown in FIGS. 1 and 2, the shaft 10 extends through the shaft passage 84, and the pinion 20, the gear 30, the magnet 40, the sensor board 50, and the electromagnetic shield 60 are disposed within the component receiving space 88. The gear 30 is fixed to the base 82 and is rotatable relative to the housing 80 about their respective rotation axes 32B, 34B, 38B. The sensor board 50 is disposed to enclose most of the component receiving space 88 with the electromagnetic shield 60 disposed on the first surface 52 of the sensor board 50. In an assembled state, as shown in FIG. 4, the magnetic field sensor 56 and the electromagnetic shield 60 are disposed at a distance 89 from the magnet 40 provided on the gear 30 in a direction parallel to the central axis C. The communication board 70 is disposed within the housing 80 on the opposite side of the base 82 from the component receiving space 88. As shown in the embodiment of FIG. 1, a number of fasteners 90 may be used to secure the multi-turn measurement system in an assembled state.

[0024] The multi-turn measurement system measures the rotation of shaft 10 about central axis C and the angular position of shaft 10 about central axis C, as will be described in more detail below.

[0025] Rotation of shaft 10 about central axis C may be driven by rotation of spool 16 or may be driven directly by an external element. As shaft 10 rotates about central axis C, pinion 20 simultaneously rotates about central axis C, driving gears 30 to rotate about their corresponding axes of rotation 32B, 34B, 38B shown in FIG. 3. Because pinions 20 have different numbers of teeth 22t, 24t and some of gears 30 have different numbers of teeth 32t, 34t, 38t engaging pinions 20, gears 30 each have a different gear ratio and each have a different angular position about their axes of rotation 32B, 34B, 38B. The configuration of the associated teeth 22t, 24t of pinion 20 and teeth 32t, 34t, 38t of gear 30, as well as the engagement of different gears 30 with different pinions 20, requires multiple rotations of shaft 10 for each of the gears 30 to reach a position returned to the same starting angular position.

[0026] Each of the magnets 40 has a magnetic field that changes based on the angular position of the corresponding gear 30 due to the rotation of the corresponding gear 30. Magnetic field sensors 56 aligned with the magnets 40 each sense the magnetic field of one of the magnets 40, as shown in Figures 2 and 4. Each of the magnetic field sensors 56 outputs a sensor signal to the integrated circuit 58 indicative of the magnetic field of the magnet 40 with which the magnetic field sensor 56 is aligned. The sensor signal output by the magnetic field sensor 56 changes as the magnetic field of each of the magnets 40 rotates due to the rotation of the corresponding gear 30. Locating the magnetic field sensor 56 within the sensor passage 62 of the electromagnetic shield 60 limits the effect of external electric fields and stray magnetic fields from other magnets 40 with which the magnetic field sensor 56 is not aligned on the detection of the magnetic field of the aligned magnet 40, improving the quality of the sensor signal output by the magnetic field sensor 56.

[0027] The integrated circuit 58 receives a sensor signal from each of the magnetic field sensors 56. In the embodiment shown, the integrated circuit 58 receives three sensor signals: a first sensor signal representative of the magnetic field of the first magnet 42 about the first axis of rotation 32B, a second sensor signal representative of the magnetic field of the second magnet 44 about the second axis of rotation 34B, and a third sensor signal representative of the magnetic field of the third magnet 46 about the third axis of rotation 38B.

[0028] Because the magnetic field of each of the magnets 40 varies due to the rotation of the corresponding gear 30, the sensor signals received by the integrated circuit 58 are representative of the angular position of each of the gears 30 at a given time. An algorithm stored in the integrated circuit 58 processes the corresponding sensor signals based in part on the Vernier principle. The integrated circuit 58 stores possible combinations of the three sensor signals from the magnetic field sensors 56, each associated with a unique rotational position of the shaft 10, including both the number of revolutions of the shaft 10 and the angular position of the shaft 10 at that revolution. That is, because the gears 30 each have different gear ratios and each have different angular positions about their rotational axes 32B, 34B, 38B through multiple revolutions of the shaft 10, each set of three sensor signals representative of the magnetic fields of the magnets 40 provided on the gears 30 are distinguishable and can be individually associated with a distinct rotational position of the shaft about the central axis C. In one embodiment of the integrated circuit 58, each combination of sensor signals representing the magnetic field of the magnet 40 during rotation of the gear 30 can be associated with a unique rotational position of the shaft 10, up to a maximum of 84 revolutions for each of the clockwise and counterclockwise rotational directions of the shaft 10 about the central axis C.

[0029] The integrated circuit 58 determines a unique rotational position of the shaft 10 at a given time based on execution of an algorithm to ascertain a unique rotational position associated with the sensor signals received at a given time. The integrated circuit 58 can determine a unique rotational position of the shaft 10 at any given time during operation of the multi-turn measurement system, including immediately after turning on the multi-turn measurement system. In one embodiment, the integrated circuit 58 determines a unique rotational position of the shaft 10 based solely on the sensor signals received from the magnetic field sensor 56.

[0030] The integrated circuit 58, implemented as iC-MNF manufactured by iC Haus, is adapted to perform the described calculations to determine the specific relationships of angular velocity and angular position between the gears 30. The multiple pinions 20 allow the integrated circuit 58 to process sensor signals from the magnetic field sensor 56 for gears 30 having fewer teeth 32t, 34t, 38t, reducing the overall size of the multi-turn measurement system.

[0031] The integrated circuit 58 transmits the unique rotational position of the shaft 10 as an output signal to the communication board 70 in a format readable by the communication board 70. In one embodiment, the integrated circuit 58 outputs the output signal as a serial peripheral interface (SPI) signal. The communication board 70 shown in Figures 1 and 2 transmits the output signal from the integrated circuit 58 to a device external to the multi-turn measurement system. Multiple communication boards 70 are interchangeable, and the particular communication board 70 used with the multi-turn measurement system is selected based on the desired connection configuration and signal format of the output signal.

Claims

1. 1. A multi-turn measurement system comprising: The multi-turn measurement system comprises: a shaft (10), - a number of gears (30); - a plurality of pinions (20) engaged with said plurality of gears (30), the rotation of said plurality of pinions (20) driving the rotation of said plurality of gears (30) around a central axis (C); - a plurality of magnets (40), each disposed on one of said plurality of gears (30) and having a magnetic field that varies based on the angular position of one of said plurality of gears (30); - a plurality of magnetic field sensors (56), each arranged to sense the magnetic field of one of the plurality of magnets (40); In addition to providing The plurality of pinions (20) are disposed on the shaft (10) and rotate together with the shaft (10) around the central axis (C). Multiturn measuring system.

2. Each of the plurality of pinions (20) has a different number of teeth (22t, 24t), and the plurality of pinions (20) rotate simultaneously around the central axis (C).

2. The multi-turn measurement system of claim 1.

3. The plurality of pinions (20) includes a first pinion (22) and a second pinion (24) disposed at different positions along the central axis (C).

3. A multi-turn measurement system according to claim 2.

4. The plurality of gears (30) includes a first gear (32) and a second gear (34) having different numbers of teeth (32t, 34t); the first gear (32) and the second gear (34) are disposed at different locations along the central axis (C); The first gear (32) is engaged with the first pinion (22); The second gear (34) is engaged with the second pinion (24).

4. A multi-turn measurement system according to claim 3.

5. the plurality of gears (30) includes a third gear (38) aligned with the first gear (32) along the central axis (C) and engaged with the first pinion (22); 5. A multi-turn measurement system according to claim 4.

6. Each of the plurality of magnets (40) is centrally disposed on a rotation axis (32B, 34B, 38B) of one of the plurality of gears (30); a magnetization direction (42M, 44M, 46M) of each of the plurality of magnets (40) extends in a diametric direction (32D, 34D, 38D) of one of the plurality of gears (30); 2. The multi-turn measurement system of claim 1.

7. The plurality of magnetic field sensors (56) are disposed on a surface (52) of the sensor board (50) facing the magnet (40); Each of the plurality of magnetic field sensors (56) is aligned with one of the plurality of magnets (40) in a direction parallel to the central axis (C).

2. The multi-turn measurement system of claim 1.

8. The sensor board (50) and the gears (30) may further include an electromagnetic shield (60), Each of the plurality of magnetic field sensors (56) is disposed within one of a plurality of passages (62) extending through the electromagnetic shield (60). A multi-turn measurement system according to claim 7.

9. The shaft (10) has a first end (12) and a second end (14); The first end (12) is a free end, The second end (14) is configured to be rotatably fixed to a spool (16) that extends around a portion of the shaft (10).

2. The multi-turn measurement system of claim 1.

10. Further comprising an integrated circuit (58); the integrated circuit (58) is connected to the plurality of magnetic field sensors (56) and receives a plurality of signals representative of the magnetic field of each of the plurality of magnets (40); 2. The multi-turn measurement system of claim 1.

11. the integrated circuit (58) determines the number of rotations and the angular position of the shaft (10) about the central axis (C) based on the signal; A multi-turn measurement system according to claim 10.

12. the integrated circuit (58) associates a unique rotational position of the shaft (10) with each of a plurality of combinations of the signals, the unique rotational position including both the number of revolutions of the shaft (10) and the angular position of the shaft (10).

12. A multi-turn measurement system according to claim 11.

13. the integrated circuit (58) is capable of determining the unique rotational position at any given time during operation of the multi-turn measurement system; 13. A multi-turn measurement system according to claim 12.

14. the integrated circuit (58) determines the unique rotational position based solely on the signal; 13. A multi-turn measurement system according to claim 12.

15. a communication board (70) for receiving an output signal representative of the unique rotational position from the integrated circuit (58); The communication board (70) transmits the output signal to the outside of the multi-turn measurement system.

13. A multi-turn measurement system according to claim 12.

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