JPH0358471B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for determining the direction of rotation that makes it possible to determine the direction of rotation using only one sensor. Conventionally, there are digital tachometers that can detect the direction of rotation, but they all require two or more mark sensors ((1) Hokukura et al.: "Dimension measurement using optical sensors", Sensor Technology, 1982). June issue (Information Research Committee), (2) Hiroshi Fukuzawa; “Two-sensor type digital tachometer with rotation direction discrimination function” (Patent application No. 57-051616)), One-sensor type digital rotation speed There is no meter that can detect the direction of rotation. 3.1 The simplest system In Figure 1, 1 is a circle whose center is on the rotation axis of the rotating body and perpendicular to the rotation axis, and O is the center of this circle and the rotation center. M ₁ , M ₂ , and M ₃ are objects to be detected, or marks, provided in this order clockwise along the circumference of 1, and ∠M ₁ OM ₂ = θ ₁₂ ,
∠M ₂ OM ₃ =θ ₂₃ , ∠M ₃ OM ₁ =θ ₃₁ , 2 is a mark sensor as a sensor for detecting the object to be detected, and 3 is an electronic device. It is assumed that the rotating shaft rotates ^twice at a uniform speed cm, the marks are sequentially detected by the mark sensor 2, and the passing time interval between marks is counted by the built-in counter of the electronic device 3. When the rotation axis rotates, the angle θ ₁₂ ,
The count values corresponding to θ ₂₃ and θ ₃₁ are respectively C ₁₂ , C ₂₃ ,
C ₃₁ . The number of revolutions is the sum of these counts C
Using N[rps]≈f/C, f is the frequency of the standard clock for time interval measurement of the built-in counter of the electronic device 3. In this system, it is impossible to predict whether the rotation direction is clockwise or counterclockwise, or which mark will be detected at a certain point in time. Table 1 shows all possible cases,
These are given names of modes 1 to 6.

【table】

[Table] In electronic device 3, one set of count values C ₁₂ , C ₂₃ , C ₃₁
Each time you finish counting, compare the three sets of the first and second counted values, the second and third counted values, and the third and first counted values to determine whether they are greater (>). Check the number of times and the number of less than (<). These times are also shown in Table 1. It can be seen from Table 1 that in the case of clockwise rotation, (> number of times) >(< number of times), and conversely, (> number of times) <(< number of times) in case of counterclockwise rotation. In other words, the direction of rotation can be determined by comparing the obtained count values as shown in Table 1 and further performing (the number of times >) and (the number of times <). The electronic device 3 can be constructed using a digital IC or the like or a single-chip microcomputer. After counting the time interval of the mark detection signal output (pulse train) as in the case of this embodiment using the built-in counter and clock signal generator of the single-chip microcomputer, the rotation speed is calculated using the calculation function. It is easy to determine the rotation direction by comparing the count values. 3.2 A system with faster response In the simplest system described above, the rotational speed can be calculated and the rotational direction can be determined.In other words, a "response" occurs at the end of counting a set of C ₁₂ , C ₂₃ , and C ₃₁ , that is, 1. After it rotates. In order to speed up this response, the circle 1 described above may be equally divided into several sector shapes. For example, to get a response after 1/4 rotation, do the following: Figure 2
Divide circle 1 equally into four sectors as shown, and mark the circumference of each sector M ₁₁ , M ₁₂ , M ₁₃ ; M ₂₁ , M ₂₂ ,
M ₂₃ ,; M ₃₁ , M ₃₂ , M ₃₃ ; M ₄₁ , M ₄₂ , M ₄₃ are arranged and located in this order, ∠M ₁₁ OM ₁₂ = ∠M ₂₁ OM ₂₂ = ∠M ₃₁ OM ₃₂ = M ₄₁ OM ₄₂ = θ ₁₂ , ∠M ₁₂ OM ₁₃ = ∠M ₂₂ OM ₂₃ = ∠M ₃₂ OM ₃₃ = ∠M ₄₂ OM ₄₃ = θ ₂₃ , ∠M ₁₃ OM ₁₁ = ∠M ₂₃ OM ₂₁ = ∠M ₃₃ OM ₃₁ = ∠ M ₄₃ OM ₄₁ = θ ₃₁ . When the rotating body rotates, the mark sensor 2 sequentially detects the marks in the same way as described above, and the passing time interval between the marks is counted by the counter built in the electronic device 3, and the angles θ ₁₂ , θ ₂₃ , θ ₃₁ are calculated. Let the corresponding count values be C ₁₂ , C ₂₃ , and C ₃₁ , respectively. The rotation speed is C ₁₂ +
N[rps]≈f/4C using C ₂₃ +C ₃₁ =C, where f is the clock frequency of the counter. The denominator is a coefficient obtained by dividing circle 1 into four sector shapes. The fan shape obtained by dividing circle 1 into equal parts is n
In the case of , the coefficient is n. Assuming that the rotational speed of the rotating body is constant, the response becomes faster as the number of segments of circle 1 increases, but
The error in rotational speed increases. This is due to a so-called ±1 count error included in the count value of the counter. 3.3 Comments for generalizing the system Since the claims generally describe the fan shape and the number of objects to be detected without specifying it, I would like to add a comment here. The circle is regarded as a special case of sector shape, and the number of segments is n
If ≧1, then FIG. 1 corresponds to the case where n=1, and FIG. 2 corresponds to the case where n=4. The number of marks on the circumference of each sector is not limited to three, and p (≧3) marks can be provided. Figure 1
In the case of θ ₁₂ < θ ₂₃ < θ ₃₁ > θ ₁₂ , (number of <) −
(Number of >) = 1, so C ₁₂ , C ₂₃ , C ₂₃ and
All of C ₃₁ , C ₃₁ and C ₁₂ must be compared. As shown in Figure 3, if four marks are provided and θ ₁₂ < θ ₂₃ < θ ₃₄ < θ ₄₁ > θ ₁₂ , then (number of <) - (number of >) = 2. Therefore, C ₁₂ and C ₂₃ , C ₂₃ and C ₃₄ , C ₃₄ and C ₄₁ , C ₄₁
It is sufficient to compare three of the four pairs of and C ₁₂ . As shown in Figure 4, even if four marks are provided, (number of <) - (number of >) = 0, as θ ₁₂ <θ ₂₃ >θ ₃₄ <θ ₄₁ >θ ₁₂ . If it is, the direction of rotation cannot be determined. However, if there are five marks as shown in Figure 5,
If θ ₁₂ <θ ₂₃ >θ ₃₄ <θ ₄₅ <θ ₅₁ >θ ₁₂ , then (number of <) - (number of >) = 1, but C ₁₂ and C ₂₃ , C ₂₃ and C ₃₄ , C ₃₄ and C ₄₅ ,
The direction of rotation cannot be determined unless all five pairs of C ₄₅ and C ₅₁ and C ₅₁ and C ₁₂ are compared. Note that in each of the above embodiments, the count value obtained by counting the passing time interval between marks with a counter is used, but the present invention is not limited to this. It is also possible to obtain a measured value such as a voltage corresponding to the interval, and even in such a case, the effect that it is possible to determine the rotation direction using a single sensor using the measured value is the same as in each of the above embodiments. It is. 3.4 Effects of this invention The feature of this invention is that it is possible to determine the direction of rotation of a rotating body using only one sensor. A single-sensor type digital tachometer that can only measure rotational speed can be constructed using marks, mark sensors, single-chip microcomputers, etc., but it is possible to construct a single-sensor type digital tachometer that can measure only the rotational speed. By simply adding , the direction of rotation can be determined. This is simple and effective when controlling the forward and reverse rotational speed of an electric motor.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the simplest embodiment of the method of the present invention, FIG. 2 is a block diagram showing an embodiment with faster response, and FIG. 3 is a block diagram showing an embodiment using four detected objects. FIG. 4 is a block diagram showing an example in which the rotational direction cannot be determined even when four detected objects are used, and FIG. 5 is a block diagram showing the simplest embodiment of the invention set forth in claim 2. 1... Circle, 2... Mark sensor, 3... Electronic device, M ₁ ~ M ₅ , M ₁₁ ~ M ₁₃ , M ₂₁ ~ M ₂₃ , M ₃₁ ~
M ₃₃ , M ₄₁ ~ M ₄₃ ... mark.

Claims (1)

[Scope of Claims] 1. As stated in the main text and shown in the drawings, a circle having its center on the rotation axis of a rotating body and perpendicular to the rotation axis is divided into one or more equiangular sectors of number n. , on the circumference of the first sector in the circumferential direction, objects to be detected M ₁₁ , M ₁₂ , M ₁₃ , . . . where p is an integer of 3 or more are placed.
..., M _1p , and the object to be detected is on the circumference of the second sector.
M ₂₁ , M ₂₂ , M ₂₃ , ......, M _2p , and objects to be detected M ₃₁ , M ₃₂ , M ₃₃ , ... on the third fan-shaped circumference
…, M _3p are arranged in this order on the circumference of the n-th sector, and the objects to be detected M _o1 , M _o2 , M _o3 , ……, M _op are arranged in this order, and there are two sectors. In the above case, ∠M ₁₁ OM ₁₂ = ∠M ₂₁ OM ₂₂ = ∠M ₃₁ OM ₃₂ =... = ∠M _o1 OM _o2 = θ ₁₂ , ∠M ₁₂ OM ₁₃ = ∠M ₂₂ OM ₂₃ = ∠M ₃₂ OM ₃₃ =…… =∠M _o2 OM _o3 =θ ₂₃ , ∠M ₁₃ OM ₁₄ =∠M ₂₃ OM ₂₄ =∠M ₃₃ OM ₃₄ =…… =∠M _o3 OM _o4 =θ ₃₄ , 〓 ∠M _{1(p -1)} OM _1p =∠M _2(p-1) OM _2p =∠M _3(p-1) OM _3p =... =∠M _o(p-1) OM _op =θ _(p-1)p , ∠M _1p OM ₂₁ =∠M _2p OM ₃₁ =∠M _3p OM ₄₁ =……=∠M _op OM ₁₁ =θ _p1 , θ ₁₂ ＜θ ₂₃ ＜θ ₃₄ ＜……＜θ _(p-1)p ＜ θ _p1 , and when the rotating body rotates, these detected objects are detected by one sensor, and the time interval from detecting one detected object to detecting the next detected object is The process of measuring is performed on 4 or more detected objects in number q that are consecutively detected,
Let x be any integer, and the time interval measurement values from x+1st to x+qth are C _x+1 , C _x+2 , C _x+3 ,
C _x+4 ,......, C _x+q-1 , C _x+q , and C _x+1 and C _x+2 ;
C _x+2 and C _x+3 ; C _x+3 and C _x+4 ; ………; C _x+q-1 and
C _x+q ; Compare the magnitude of at least three consecutively ranked sets of q pairs of C _x+q and C _x+1 , check whether the inequality sign is > or <, and calculate the total number of > A method to determine the direction of rotation by comparing the total number of < and <. 2. As stated in the main text and shown in the drawings, a circle centered on the rotation axis of the rotating body and perpendicular to the rotation axis is divided into one or more equiangular sectors of number n, and counted in the circumferential direction. On the circumference of the first sector, there are detected objects M ₁₁ , M ₁₂ , M ₁₃ , ......, where p is an integer of 3 or more.
M _1p , and the object to be detected is on the circumference of the second sector.
M ₂₁ , M ₂₂ , M ₂₃ , ......, M _2p , and objects to be detected M ₃₁ , M ₃₂ , M ₃₃ , ... on the third fan-shaped circumference
…, M _3p , ………, On the circumference of the n-th sector, the objects to be detected M _o1 , M _o2 , M _o3 , ………, M _op are arranged in this order, and there are two sectors. In the above case, ∠M ₁₁ OM ₁₂ = ∠M ₂₁ OM ₂₂ = ∠M ₃₁ OM ₃₂ =... = ∠M _o1 OM _o2 = θ ₁₂ , ∠M ₁₂ OM ₁₃ = ∠M ₂₂ OM ₂₃ = ∠M ₃₂ OM ₃₃ =…… =∠M _o2 OM _o3 =θ ₂₃ , ∠M ₁₃ OM ₁₄ =∠M ₂₃ OM ₂₄ =∠M ₃₃ OM ₃₄ =…… =∠M _o3 OM _o4 =θ ₃₄ , 〓 ∠M _{1(p -1)} OM _1p =∠M _2(p-1) OM _2p =∠M _3(p-1) OM _3p =... =∠M _o(p-1) OM _op =θ _(p-1)p , ∠M _1p OM ₂₁ = ∠M _2p OM ₃₁ = ∠M _3p OM ₄₁ =...=∠M _op OM ₁₁ = θ _p1 , and θ ₁₂ , θ ₂₃ , θ ₃₄ , ......, θ _{(p -1)p}
，
Of θ _p1 , θ ₁₂ and θ ₂₃ ; θ ₂₃ and θ ₂₄ ; ………; θ _(p-1)p
and θ _p1 ; When comparing the sizes of p pairs of θ _p1 and θ ₁₂ , the inequality sign is (number of pairs that is <) - (number of pairs that are >) ≧ 1
When the rotating body rotates, these detected objects are detected by one sensor, and the time interval from detecting one detected object to detecting the next detected object is measured. This process is performed on p+1 detected objects that are detected continuously, and the time interval measurement values from x+1th to x+pth are calculated as C _x+1 , C _x+2 , C _x+3 , where x is an arbitrary integer. C _x+4 ，……
…, C _x+p-1 , C _x+p , C _x+1 and C _x+2 ; C _x+2 and
C _x+3 ；C _x+3 and C _x+4 ；C _x+p-1 and C _x+p ；C _x+p
Compare the sizes of p sets of and C _x+1 , and the inequality sign is >
A method of determining the direction of rotation by checking whether it is or <, and then comparing the total number of > and the total number of <.