JP2005188928A - Absolute angle detection device and absolute angle detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To preferably constitute a driven gear comparably small in the case of calculating the absolute angle based on the relative angles of the two driven gears. <P>SOLUTION: A first main gear 16 of m teeth, and a second main gear 18 of n teeth are fixed on the rotation shaft 12 with the rotation axis 14 as a rotation center. A first driven gear 20 of p teeth is made to engage wit the first main gear and a second driven gear 22 of p teeth is made to engage with the second main gear. The computing part 28 computes, based on the detection results of the relative angle ϕ of the first driven gear, and the relative angle ψ of the second driven gear, absolute angle θ=(ϕ-ψ)p/(m-n). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a technique for detecting an absolute angle of a rotating body, and more particularly to a technique for detecting an absolute angle based on relative angles of a plurality of gears.

  A technique for obtaining an absolute angle of a rotating body is required in various fields. For example, a technique for detecting an absolute angle of a steering wheel or the like is required in the automobile manufacturing field.

  Patent Document 1 below discloses a technique for obtaining an absolute angle of a rotating body by meshing two driven gears having different numbers of teeth with a main gear rotating together with the rotating body and detecting the relative angle of each driven gear. Is disclosed. In Patent Document 2 below, a main gear that rotates together with a rotating body is meshed with a driven gear that rotates at a lower speed than the rotating body and a driven gear that rotates at a higher speed than the rotating body, and the relative angle of each driven gear is determined. A technique for obtaining an absolute angle of a rotating body by detection is disclosed. In these techniques, an absolute angle of ((number of teeth of one driven gear) × (number of teeth of the other driven gear) / (number of teeth of the main gear)) × 360 ° can be detected.

  In Patent Document 3 below, the driven gear that rotates with the rotating body is engaged with the driven gear, and the moving distance of the driving body that moves with the rotation of the driven gear and the relative angle of the driven gear are detected and rotated. Techniques for determining the absolute angle of the body are disclosed.

Japanese National Patent Publication No. 11-500828 Japanese Patent Laid-Open No. 2002-340618 JP 2002-213910 A

  In the techniques disclosed in Patent Documents 1 and 2, when the range in which the absolute angle can be obtained is widened, it is necessary to further increase the number of teeth of the driven gear while minimizing the difference in the number of teeth of the two driven gears. . That is, it is necessary to increase the size of the driven gear, which may be difficult due to the space of the apparatus. Further, when the number of teeth of the driven gear is increased in this way, the rotation rate of the driven gear with respect to the rotating body is lowered, and accurate (high resolution) detection of the relative angle of the driven gear becomes difficult.

  An object of the present invention is to develop an absolute angle detection device capable of configuring the size of a driven gear to be relatively small.

  Another object of the present invention is to develop an absolute angle detection device having a structure that can easily improve detection resolution.

  Still another object of the present invention is to develop an absolute angle detection device in which the number of teeth of the two driven gears is the same.

  The absolute angle detection device according to the present invention is a concentric two gears having a rotating shaft of a rotating rotating body as a central axis of the gear and rotating together with the rotating body, the number of teeth being different from each other and not being a divisor of the other. The first main gear and the second main gear having the first main gear, the first driven gear meshed with the first main gear, the first detecting means for detecting the relative angle of the first driven gear, and the same tooth as the first driven gear The second driven gear having a number and meshed with the second main gear, the second detecting means for detecting the relative angle of the second driven gear, and the detection results of the first detecting means and the second detecting means, Calculating means for calculating an absolute angle of the rotating body.

  The first main gear and the second main gear are concentric gears having the rotation axis of the rotating body as the rotation center axis, and are fixed to the rotating body and rotate together with the rotating body. The number of teeth of the first main gear and the number of teeth of the second main gear have different numbers that are not divisible. The first driven gear meshes with the first driven gear, and the second driven gear meshes with the second driven gear. The number of teeth of the first driven gear and the second driven gear is the same. Therefore, the first driven gear and the second driven gear rotate at a speed defined by the number of teeth of the first main gear and the number of teeth of the second main gear, respectively. The combination of the relative angle of the first driven gear detected by the first detection means and the relative angle of the second driven gear detected by the second detection means is the number of teeth of the first main gear and the second main gear. And a long period defined by the number of teeth of the driven gear and the number of teeth of the driven gear. Therefore, by associating the combination of the relative angle of the first driven gear and the relative angle of the second driven gear with the absolute angle of the rotating body, the absolute angle of the rotating body is detected within the range of angles corresponding to this long cycle. can do. The arithmetic means calculates the absolute angle of the rotating body based on this correspondence. The association may be performed based on an arithmetic expression, or may be performed based on a reference LUT (lookup table).

  The relative angle is an angle given without distinguishing how many rotations. The absolute angle is an angle given including information on how many rotations. For example, in the case of 360 °, the relative angle is given in the range of 0 ° to 360 ° regardless of the number of rotations, but the absolute angle is 0 ° to 360 ° in the first week and 0 ° to 360 in the second week. ° (or 360 ° to 720 °), such as 0 ° to 360 ° (or 720 ° to 1080 °) in the third week.

  According to this configuration, the absolute angle detection range can be expanded by increasing the number of teeth of the first main gear and the second main gear. For this reason, it is possible to take the structure which keeps the magnitude | size of a 1st driven gear and a 2nd driven gear comparatively small, and the mounting to a limited space becomes easy. Moreover, the 1st driven gear and the 2nd driven gear with the same number of teeth can be produced using the same components. Therefore, the types of parts are not increased unnecessarily.

  Preferably, in the absolute angle detection device according to the present invention, the calculating means sets the number of teeth of the first main gear to m, the number of teeth of the second main gear to n, and the number of teeth of the first driven gear and the second driven gear. p, where the relative angle detected by the first detecting means is φ, the relative angle detected by the second detecting means is ψ, and the absolute angle of the rotating body is θ, when φ ≧ ψ, θ = ( When φ−ψ) p / (mn) and φ <ψ, the absolute angle of the rotating body is calculated by calculating θ = (φ−ψ + 360 °) p / (mn).

  Preferably, in the absolute angle detection device of the present invention, the difference between the number of teeth of the first main gear and the number of teeth of the second main gear is one. By setting the difference in the number of teeth to 1, the absolute angle detection range can be easily widened. Desirably, in the absolute angle detection device of the present invention, the number of teeth of the first driven gear is smaller than the number of teeth of the first main gear and the number of teeth of the second main gear.

  The absolute angle detection method of the present invention uses two rotations of a rotating rotating body as a central axis of a gear and two concentric gears rotating together with the rotating body, the number of teeth being different from each other and not being a divisor of the other. A first main gear and a second main gear having a first gear, a first driven gear meshed with the first main gear, and a second driven gear meshed with the second main gear having the same number of teeth as the first driven gear. A method for detecting an absolute angle of the rotating body using a device comprising: a step of detecting a relative angle of the first driven gear; a step of detecting a relative angle of the second driven gear; Calculating the absolute angle of the rotating body based on the relative angle of the first driven gear and the relative angle of the second driven gear.

  Hereinafter, typical embodiments of the present invention will be described.

  FIG. 1 is a diagram showing a schematic configuration of an absolute angle detection device 10 according to the present embodiment. The absolute angle detection device 10 includes a shaft 12 as a rotating body. The shaft 12 rotates about the rotation shaft 14 as a rotation center. The shaft 12 is rotated in accordance with, for example, a rotation operation of a car handle. The absolute angle detection device 10 is a device that calculates the absolute angle of the shaft 12, and thereby the absolute rotation angle of the handle is derived.

  A first main gear 16 having a number of teeth m and a second main gear 18 having a number of teeth n are integrally attached to the shaft 12. The number of teeth m and the number of teeth n are set to be different numbers, and one is not a divisor of the other. The two main gears 16 and 18 rotate together with the shaft 12 with the rotation shaft 14 as a central axis. The first main gear 16 meshes with a first driven gear 20 having the number of teeth p constituting a spur gear. Further, the second main gear 18 is engaged with a second driven gear 22 having the number of teeth p, which also forms a spur gear. The number of teeth p is a number smaller than both the number of teeth m and n. Note that the axes of these two driven gears 20 and 22 are not necessarily parallel to the axes of the corresponding main gears 16 and 18 (rotating shaft 14).

  The relative angle of the first driven gear 20 is detected by the first detector 24, and the relative angle of the second driven gear 22 is detected by the second detector 26. There are various methods for detecting the relative angle. For example, the relative angle may be obtained by detecting the magnetism associated with the magnets installed in the driven gears 20 and 22 with the magnetic detection element.

  The detected relative angle signal is input to the calculation unit 28. The calculation unit 28 includes hardware having a calculation function and software (program) that defines the operation of the hardware. Then, as will be described later, the absolute angle is calculated based on an arithmetic expression. The absolute angle calculated by the calculation unit 28 is output through the output unit 30. The output unit 30 may be a connection terminal that outputs a signal to an external device, or may have a display function such as a liquid crystal display and display a result.

Next, an arithmetic expression for the calculation unit 28 to calculate the absolute angle will be described. It is assumed that the shaft 12 rotates counterclockwise by an angle θ from the reference position around the rotation axis 14 with the rotation of the handle or the like. At this time, if the clockwise relative angle of the first driven gear 20 is φ,
φ = (m / p) θ (1)
It is. Similarly, the clockwise relative angle ψ of the second driven gear 22 is
ψ = (n / p) θ (2)
It is. From formula (1) -formula (2), φ−ψ = (mn) θ / p (3)
Is obtained. Solving this for θ θ = (φ−ψ) p / (mn) (4)
Is obtained. Equation (4) gives the absolute angle θ when φ ≧ ψ. When φ <ψ
θ = (φ−ψ + 360 °) p / (mn) (5)
Gives the absolute angle θ.

  Expressions (4) and (5) are applicable to any combination of the number of teeth where m ≠ n. However, when m≈n, the absolute angle can be obtained for a wider range of angles. Therefore, it is particularly desirable to satisfy the relationship | m−n | = 1.

  Further, it is desirable that one of m and n is not a divisor of the other. For example, when n is a divisor of m, it is expressed as m = nk using a natural number k. Further, φ / ψ = m / n = k, that is, φ = ψk is obtained from the formula (1) / formula (2). Substituting these into equation (4) results in θ = ψp / n and the information on the two relative angles is degenerated, giving information that is simply a fixed multiplication of the relative angle ψ of the second driven gear 22. It turns out that it is only.

  The absolute angle detection range becomes wider as the number of teeth p of both driven gears 20 and 22 is larger. Therefore, the number of teeth p may be larger than the number of teeth m and the number of teeth n. On the other hand, when p / (mn) ≦ 1, the absolute angle θ is in the range of 360 ° or less and lacks the advantage of calculating the absolute angle. Therefore, it is desirable that p / (mn)> 1.

  FIG. 2 is a graph showing the relationship between the relative angle and the absolute angle. The horizontal axis is the true absolute angle (not the calculated value) of the rotating body, and the vertical axis is the detected relative angle and the calculated absolute angle. Here, as an example, a case where m = 5, n = 4, and p = 2 is shown. The wavy line 40 is the relative angle φ of the first driven gear 20, the dotted line 42 is the relative angle ψ of the second driven gear 22, and the solid line 44 is the calculated absolute angle θ.

  In this example, while the shaft 12 makes one rotation (360 °), the first driven gear 20 rotates m / p = 5/2, and the second driven gear 22 rotates n / p = 2. For this reason, when the shaft 12 rotates twice (720 °), the first driven gear 20 rotates five times (see the dotted line 40), the second driven gear 22 makes four turns (see the dotted line 42), and at 0 ° Is in the same state. At 720 ° during this period, there is no overlap in the relationship between φ and ψ, and the absolute angle θ obtained by the equations (4) and (5) increases from θ = 0 ° to 720 ° (see the solid line 44). ). If the absolute angle θ is outside this range, the value repeats from θ = 0 ° to 720 °. This corresponds to the relationship between φ and ψ being repeated with a period of 720 °.

The repetition period, that is, the range [θ] in which the absolute angle θ can be calculated is the difference between the case where (φ−ψ) = 360 ° and the case where (φ−ψ) = 0 ° in the equation (4). ,
[Θ] = 360 ° p / (mn) (6)
Given in. In the case of m = 5, n = 4, and p = 2 shown in FIG. 2, [θ] = 720 °. For example, when m = 108, n = 107, and p = 36, the absolute angle θ can be detected in the range of [θ] = 12960 °.

  Next, a modification of the present embodiment will be described with reference to FIG. The perspective view of FIG. 3 shows a shaft 50 as a rotating body and various installed gears. Specifically, the first main gear 52 and the second main gear 54 are attached to the shaft 50 at a distance. The first main gear 52 is meshed with a first driven gear 56 constituting a spur gear, and the second main gear 54 is meshed with a first driven gear 58 constituting a spur gear. Thus, the positional relationship between the first main gear 52 and the second main gear 54 is not particularly limited. That is, as intended in FIG. 1, both the main gears 16 and 18 may be formed integrally, or both the main gears 52 and 54 are provided at a sufficient distance as shown in FIG. May be. The installation position can be flexibly changed according to the installation space of the main gear and the corresponding driven gear.

It is the schematic which shows the structure of the absolute angle detection apparatus which concerns on this Embodiment. It is a graph which shows the relationship between the detected relative angle and the calculated absolute angle. It is a perspective view which shows a modification.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Absolute angle detection apparatus, 12 Shaft, 14 Rotating shaft, 16 1st main gear, 18 2nd main gear, 20 1st driven gear, 22 2nd driven gear, 24 1st detection part, 26 2nd detection part, 28 Calculation unit, 30 output unit, 40 wavy line, 42 dotted line, 44 solid line.

Claims (5)

A first main gear and a second gear, which are two concentric gears that rotate with the rotating body, with the rotating shaft of the rotating rotating body as a central axis of the gear, and one of them is different from each other and the number of teeth is not a divisor of the other. The main gear,
A first driven gear meshed with the first main gear;
First detecting means for detecting a relative angle of the first driven gear;
A second driven gear having the same number of teeth as the first driven gear and meshed with the second main gear;
Second detecting means for detecting a relative angle of the second driven gear;
Calculation means for calculating an absolute angle of the rotating body based on detection results of the first detection means and the second detection means;
An absolute angle detection device comprising: The absolute angle detection device according to claim 1,
The calculating means includes m as the number of teeth of the first main gear, n as the number of teeth of the second main gear, p as the number of teeth of the first driven gear and the second driven gear, and the relative angle detected by the first detecting means. Is φ, the relative angle detected by the second detection means is ψ, and the absolute angle of the rotating body is θ,
When φ ≧ ψ, θ = (φ−ψ) p / (mn),
When φ <ψ, θ = (φ−ψ + 360 °) p / (mn),
An absolute angle detecting device, wherein the absolute angle of the rotating body is calculated by the following calculation. The absolute angle detection device according to claim 1,
The absolute angle detection device characterized in that the difference between the number of teeth of the first main gear and the number of teeth of the second main gear is 1. The absolute angle detection device according to claim 1,
The absolute angle detection device characterized in that the number of teeth of the first driven gear is smaller than the number of teeth of the first main gear and the number of teeth of the second main gear. A first main gear and a second gear, which are two concentric gears that rotate with the rotating body, with the rotating shaft of the rotating rotating body as a central axis of the gear, and one of them is different from each other and the number of teeth is not a divisor of the other. The main gear,
A first driven gear meshed with the first main gear;
A second driven gear having the same number of teeth as the first driven gear and meshed with the second main gear;
A method for detecting an absolute angle of the rotating body using a device comprising:
Detecting a relative angle of the first driven gear;
Detecting a relative angle of the second driven gear;
Calculating an absolute angle of the rotating body based on the detected relative angle of the first driven gear and the detected relative angle of the second driven gear;
An absolute angle detection method comprising:

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