KR101720793B1 - Apparatus for measuring rotation angle and method for operating the same - Google Patents

Abstract

An embodiment of the present invention relates to a rotation angle measuring apparatus and a method of operating the same by grasping the position of an identification point displayed on the surface of a code wheel and includes a code wheel having a plurality of identification points displayed on a surface thereof, And a rotation angle calculating unit for calculating a rotation angle of the code wheel by grasping an identification point position in a focus area photographed by the camera sensor before and after the rotation of the code wheel And the plurality of identification points have different distances from the origin and angles with respect to the reference axis, respectively.

Code wheel, rotation, angle, camera

Description

[0001] Apparatus for measuring rotation angle and method for operating same [

An embodiment of the present invention relates to a rotation angle measuring apparatus and an operation method thereof.

A rotation angle measuring device is used to determine the motion or position of an object with respect to a predetermined reference in a wide range of situations. Particularly, the optical rotation angle measuring device measures and tracks the rotational movement of the device, and includes a steering control, a valve control, an engine control, a scanner, a printer, ) And the like.

1 is a perspective view showing an apparatus for measuring a rotation angle through optical encoding.

The rotation angle measuring device has a code wheel 100 having a shaft as an axis, and this code wheel has an encode pattern 101.

An LED 110 serving as a light source means for illuminating light is provided on the upper part of the code wheel, and a detection circuit 130 is provided below the code wheel. Between the LED 110 and the encode pattern 101 may include a lens 120 that is aligned with the LED to direct the projected light in a particular path or pattern.

The LED 110 is driven by a driving signal V _input and a current limiting resistor R _{L as} shown in FIG. The detection circuit 130 includes one or more photodetectors such as a photodiode 131 and the like. The signal detected in the photodetector is subjected to channel signal processing and then demodulated by the decoder 132. [

The rotation angle measuring device having the above-described configuration can detect the rotation angle of the code wheel 100. When the shaft is rotated by user's operation and the rotation of the code wheel 100 is performed by the rotation of the shaft, light passing through the encode pattern 101 of the rotating code wheel 100 is detected and decoded The rotation angle is detected.

However, when the above-described rotation angle measuring apparatus is to be implemented, it is inconvenient to embody a plurality of holes in the code wheel 101 in the code wheel 100.

That is, in order to form a plurality of encoded patterns through which the light passes through the code wheel 100, there is an inconvenience that the encode patterns must be precisely formed on the code wheel.

In addition, the cost of producing a code wheel increases with the formation of such a sophisticated encode pattern, which raises a problem that manufacturing cost of the rotation angle measuring apparatus as a whole increases.

An embodiment of the present invention proposes an apparatus and method for measuring the rotation angle of a code wheel, which enables the rotation angle of a code wheel to be measured without forming an encoding pattern on the code wheel.

An embodiment of the present invention is a camera system comprising a camera wheel for photographing a code wheel having a plurality of identification points displayed on a surface thereof and a specific area of the code wheel as a focus area, And a rotation angle calculating unit for calculating a rotation angle of the code wheel by grasping an identification point position within the focus area.

The plurality of identification points have different distances from the origin and angles with respect to the reference axis.

The focus area is one of the plurality of areas when the entire area of the code wheel is divided into the same size.

The rotation angle calculator calculates the rotation angle of the code wheel based on the reference axis for the identification point located in the captured focus area after the code wheel is rotated, And then calculates the difference between the current angle and the initial angle as the rotation angle of the code wheel.

The first aspect of the present invention is characterized in that a first step of grasping the angle formed by the identification points having different distances from the origin with respect to the reference axis as the initial angle before the rotation of the code wheel, A third step of analyzing the photographed image to calculate a current angle with respect to a reference number and an intrinsic number of an identification point located in the focus area; And a fourth step of calculating a difference between the initial angle before the rotation and the current angle after the rotation with respect to the identification point located in the focus area as the rotation angle of the code wheel.

The embodiment of the present invention solves the inconvenience of conventionally forming an encoding pattern on the code wheel by detecting the rotation position of the code wheel by grasping the rotation position of the identification point displayed on the surface of the code wheel. Further, since the rotation angle can be measured using the identification point without forming an encode pattern, the manufacturing cost can be reduced.

Hereinafter, a detailed description of embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the same reference numerals are used to denote the same or similar components in the drawings.

3 is a diagram showing a configuration of a rotation angle measuring apparatus according to an embodiment of the present invention.

In the embodiment of the present invention, the surface of the rotating code wheel 100 is photographed and the rotation angle is measured from the image of the photographed code wheel.

The code wheel 100 connected to the gear 150 of the shaft 151 also rotates when the shaft 151 which is a rotary shaft is rotated by a user's operation or the like. The camera sensor 140 continuously photographs the entire area or specific area of the code wheel as a short period while the rotation is performed, and measures the rotation angle from the image of the photographed code wheel 100.

By providing light as the light source means 110 such as an LED to a region to be photographed by the code wheel (hereinafter referred to as a 'focus region'), an image of a code wheel with a high resolution can be obtained.

A plurality of identification points are stamped on the entire surface of the code wheel 100. This identification point should have color and shape (e.g., a black square point on a white background, a black circle point, etc.) with a high resolution so as to be distinguished from the background color of the code wheel.

4 shows a state in which an identification point is marked on the surface of the code wheel 100. Each of the identification points has a different distance from the origin and an angle with respect to the reference axis (X axis). This is to distinguish each identification point through the image taken when the code wheel is rotated.

The number of identification points to be photographed on the code wheel varies depending on the imaging region of the camera sensor.

The camera sensor takes the entire area of the code wheel or a specific area as a focus area. Since at least one identification point must always exist in the focus area to be photographed, the minimum number of identification points varies in accordance with the focus area to be photographed. Therefore, the minimum number of identification points is one more than the number of focus areas.

That is, the number of identification points displayed on the code wheel should be at least one more than the number of the same when dividing the entire area of the code wheel into a plurality of equal sizes.

For example, referring to FIG. 4, when the focused focus area is located in the first quadrant Q1 of the code wheel, at least one of the identification points must be present in the first quadrant when the code wheel rotates. Thus, at least five identification points must be present in the code wheel.

There are no more than five identification points on the code wheel, and if there are only four identification points, the identification point may not be detected in the first quadrant. That is, if there are only four identification points M1, M2, M3, and M4 on the boundary axis of 0 DEG, 90 DEG, 180 DEG, and 270 DEG, the first quadrant Q1 ) May not be present. This is because the rotation angle calculation can not be performed if there is no discrimination point in the first quadrant.

Therefore, the minimum number of identification points should be one more than the number of focus areas.

Minimum number of identification points = code area circle area / divided focus area + 1

Therefore, if the focus area is formed in the first quadrant and the photographing is performed, the minimum number of identification points required is as follows.

Minimum number of identification points = 1 / (1/4) + 1 = 5

In order to distinguish each identification point from the image taken when the code wheel is rotated, the respective distances from the origin to the reference point are different from each other, and the distances of the identification points are d1 > d2> d3> d4> d5, respectively.

That is, the coordinates of the M1 x _1, y _1, and the coordinates of M2 x _2, y _2, and the coordinate of the M3 x _3, y _3, and the coordinates of the M4 x _4, y _4, the coordinates of M5 x _5, when the said _{y 5, root {(x 1} ) 2 + (y 1) 2}> root {(x 2) 2 + (y 2) 2}> root {(x 3) 2 + (y 3 ) ² }> root {(x ₄ ) ² + (y ₄ ) ² }> root {(x ₅ ) ² + (y ₅ ) ² }.

Assuming that there are five identification points M1, M2, M3, M4, and M5 as shown in FIG. 4, each identification point has an angle with respect to the reference axis. 72 °, 144 °, 216 ° and 288 °, respectively.

Further, the angle of each of the identification points has a constant angular difference of 72 degrees. That is, the angle of each identification point has an angular difference calculated by dividing the total 360 degrees by the number of the five identification points. That is, the discrimination point angle difference = 360 占 5 占 72 占.

In the meantime, in order to distinguish each identification point from the image taken when the code wheel is rotated, the distances from the origin and angles with respect to the reference axis are different for each identification point. In another embodiment of the present invention, The shape of the identification points and the angle with respect to the reference axis may be different from each other.

That is, if the shape of each of the identification points is differently implemented with the distances from the origin of each identification point being the same, each identification point can be distinguished. For example, the first identification point may be a rectangle, the second identification point may be circular, the third identification point may be a triangle, the fourth identification point may be a hexagon, and the fifth identification point may be a star, .

The rotation angle calculation unit 160 calculates the rotation angle by grasping the rotation position of the identification point on the code wheel photographed by the camera sensor.

When the code wheel is rotated, the identification point marked on the surface of the code wheel is also rotated and the position is changed. By calculating the rotation angle of the identification point by the rotation angle calculating unit through the image captured by the camera sensor, To calculate the angle.

In other words, the rotation angle calculating unit 160 calculates the rotation angle of the code wheel after the code wheel is rotated, with the angle of the reference point of each of the identification points before the code wheel rotated as the initial angle, And the difference between the current angle and the initial angle is calculated as the rotation angle of the code wheel. An example of calculating the rotation angle will be described in detail with reference to the flow chart of Fig.

Hereinafter, in the explanation for calculating the rotation angle, an example of FIG. 4 will be described in which the circular code wheel is divided into quarters so as to set the quadrant of the quadrant as an area to be imaged, and the minimum number of identification points to be imaged on the code wheel is 5. However, As an embodiment, the present invention can be implemented by equally dividing the code wheel into a number of parts such as 5, 6, 7, 8, etc. and setting one of them as a focus area or setting the entire code wheel as a focus area. Therefore, the minimum number of discrimination points to be photographed according to the number of divided focus areas will also be changed.

5 is a flowchart illustrating a process of measuring a rotation angle according to an embodiment of the present invention.

First, a step (S51) of grasping, as an initial angle before the rotation of the core wheel, the angle formed with the reference axis of the identification points having different distances from the origin, respectively.

For example, assuming that a circular code wheel is divided into quarters so as to set an area in which a quadrant is captured, and the number of discrimination points to be imaged on the code wheel is five, each discrimination point having distances of d1, d2, d3, d4 and d5 And the angle formed with the reference axis.

The distances and angles of the respective identification points before the rotation can be determined in various ways. The distance and angle of each identification point can be grasped by photographing the focus area before the rotation.

When the focus area before rotation is photographed and the distances and angles of the respective identification points are grasped, first, the first quadrant (0 DEG to 89 DEG; Q1) of the focus area in the code wheel is photographed before the rotation of the code wheel is performed .

Assuming that the position of the discrimination point located before the rotation of the code wheel is as shown in Fig. 6 (a), M 1 is 0 °, M 2 is 72 °, M 3 is 144 °, M 4 is 216 °, M 5 is 288 ° , And each identification point has a distance d1> d2> d3> d4> d5 from the origin.

Therefore, the identification points of M1 and M2 are observed in the focus area of the first quadrant photographed by the camera sensor. The distance (d1, d2, d3, d4, d5) of each identified point is because it is already known, the distance M1 (d1) = root {( x 1) 2 + (y 1) 2}, the distance M2 (d2) it can be seen that the ^{_{= root {(x 2) 2}} + (y 2) 2} is calculated by a, d1, identified points of M1, M2 with d2 located in the first quadrant (Q1).

In addition, since each identification point has a difference of 72 degrees, it is possible to calculate the angles of the remaining M3, M4, and M5 by calculating the angles M1 and M2 make with the reference axis (X axis). Therefore, it can be understood that M1 is located at 0 °, M2 is 72 °, M3 is 144 °, M4 is at 216 °, and M5 is at 288 ° as the positions of the entire identification points.

On the other hand, if the code wheel is rotated (S52) by the user's operation, the focus area is photographed (S53) to identify the identification point (S54) and the rotation angle can be measured (S55).

6 (a), assuming that the code wheel is rotated 100 degrees (S52) by the user's operation and rotated as the state shown in Fig. 6 (b), M1 is 100 °, M2 is 172 °, M3 is 244 °, M4 is 316 °, and M5 is 28 °. Therefore, after the rotation is performed, only the identification point of M5 located at 28 degrees exists in the first quadrant (Q1) as shown in Fig. 6 (b).

After the rotation, the first quadrant (Q1) as the focus area is photographed (S53) through the camera sensor, and only the identification point of M5 located at 28 degrees can be observed in the first quadrant (Q1).

By such a distance from the origin with respect to the observed identification points (root and hold the ^{_{{(x 5) 2 + (}} y 5) 2} = d5 acid, it can grasp the unique number of M5 of the identification points with a distance d5. That is, it can be seen that calculating the distance to the origin has d5, which shows that the identification point of M5 is located in the first quadrant.

Further, the current angle of the identified M5 identification point is calculated (S54).

The current angle of the identification point of M5 can be calculated by tan ^-1 (y ₅ / x ₅ ) by the trigonometric formula. It can be seen that M5 is located at 28 ° by the calculation angle of tan ^-1 (y ₅ / x ₅ ).

After calculating the current angle of the M5 discrimination point as described above (S54), the rotation angle of the code wheel is calculated using this (S55). That is, the difference between the initial angle before the rotation of the identification point located in the focus area and the current angle after rotation can be calculated as the rotation angle of the code wheel.

This can be expressed as follows.

Rotation angle

= 360 ° + (the current angle of the identification point present in the focus area - the first angle of the identification point present in the focus area)

= 360 ° + (the current angle of M5 - the first angle of M5)

= 360 ° + (28 ° - 288 °) = 360 ° - 260 ° = 100 °

Thus, it can be seen that the code wheel has been rotated 100 degrees.

On the other hand, in the case of a system in which the code wheel is rotated by 360 degrees or more, the code wheel is rotated once or twice for every abnormal rotation such as 360 ° and 720 °, After calculating the rotation angle in the above manner, the final rotation angle can be calculated by adding 360 ° or 720 ° according to the calculated rotation angle.

On the other hand, in order to photograph only the first quadrant area of the code wheel as a focus area as described above, one camera sensor is required. In case of multi-turn rotation, the camera sensor can be implemented with only one camera sensor, Effect.

Generally, a plurality of sensors must be provided for multi-turn rotation measurement of multiple code wheels. However, in the case of photographing only a specific focus area and measuring the rotation angle as in the present invention, only one camera sensor is provided in the multi-turn structure as shown in Fig. 7, so that the first quadrant Q1 of the first code wheel 100a, And the third quadrant (Q3) of the second code wheel 100b are simultaneously photographed, and the rotation angles of the respective quadrants are calculated, whereby the production cost can be reduced.

While the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. Accordingly, the scope of the patent of the present invention is not limited by the above-described embodiments, and it will be obvious that the patent scope covers not only the claims but also the equivalents.

1 is a perspective view showing an apparatus for measuring a rotation angle through optical encoding.

2 is a diagram showing an optical detection circuit in a conventional rotation angle measuring apparatus.

3 is a diagram showing a configuration of a rotation angle measuring apparatus according to an embodiment of the present invention.

4 is a view showing identification points on the surface of a code wheel according to an embodiment of the present invention.

5 is a flowchart illustrating a process of measuring a rotation angle according to an embodiment of the present invention.

FIG. 6 is a view showing the state before and after the rotation of the identification points on the surface of the code wheel according to the embodiment of the present invention. FIG.

FIG. 7 is a diagram illustrating a method of measuring a rotation angle of a multi-turn using one camera sensor according to an embodiment of the present invention.

Claims (16)

delete A code wheel on which a plurality of identification points different from each other with respect to a distance from an origin and an angle with respect to a reference axis are displayed on the surface; A camera sensor for photographing a specific area of the code wheel as a focus area; Calculating a rotation angle of the code wheel by grasping an identification point position in a focus area photographed by the camera sensor before and after rotation of the code wheel; / RTI > Each of the identification points having the same angular difference as the adjacent identification point, Wherein the focus area is one of the plurality of the code wheels when dividing the entire area of the code wheel into the same size, The number of identification points displayed on the code wheel is at least one more than the number of division of the entire area of the code wheel into a plurality of identical sizes, The rotation angle calculating unit calculates the rotation angle of the code wheel with respect to the reference axis for the identification point located in the focus area captured after the code wheel is rotated, And calculates the difference between the current angle and the initial angle as the rotation angle of the code wheel after grasping the angle as the current angle. A code wheel having a plurality of identification points different in angle from each other and having a shape and a reference axis on the surface; A camera sensor for photographing a specific area of the code wheel as a focus area; Calculating a rotation angle of the code wheel by grasping an identification point position in a focus area photographed by the camera sensor before and after rotation of the code wheel; / RTI > Each of the identification points having the same angular difference as the adjacent identification point, Wherein the focus area is one of the plurality of the code wheels when dividing the entire area of the code wheel into the same size, The number of identification points displayed on the code wheel is at least one more than the number of division of the entire area of the code wheel into a plurality of identical sizes, The rotation angle calculator calculates the rotation angle of the code wheel based on the reference axis for the identification point located in the captured focus area after the code wheel is rotated, As the current angle, and then calculates the difference between the current angle and the initial angle as the rotation angle of the code wheel. delete delete 4. The rotation angle measuring device according to claim 2 or 3, wherein the angle between the identification points is {360 占 ÷ number of identification points} and has the same angle. The rotation angle measuring device according to claim 2 or 3, wherein the rotation angle measuring device includes light source means for illuminating the surface of the code wheel to increase resolution at the time of photographing. delete delete A first step of grasping an angle formed by the identification points with the reference axis with respect to a code wheel on which a plurality of identification points having different angles from the reference axis and the reference axis are displayed on the surface, A second step of photographing a specific area of the code wheel as a focus area with one camera when the code wheel is rotated; A third step of analyzing the photographed image to calculate an intrinsic number of an identification point located in the focus area and a current angle with the reference axis; The fourth step of calculating the difference between the initial angle before the rotation and the current angle after the rotation with respect to the identification point located in the focus area as the rotation angle of the code wheel / RTI > Each of the identification points having the same angular difference as the adjacent identification point, Wherein the focus area is one of the plurality of the code wheels when dividing the entire area of the code wheel into the same size, Wherein the number of identification points displayed on the code wheel is at least one more than the number of division of the entire area of the code wheel into a plurality of equal sizes. A code wheel which grasps the angle formed by the identification points with the reference axis with respect to the code wheel on which a plurality of identification points having different distances from the origin and different angles from the reference axis are displayed on the surface, 1 process; A second step of photographing a specific area of the code wheel as a focus area with one camera when the code wheel is rotated; A third step of analyzing the photographed image to calculate an intrinsic number of an identification point located in the focus area and a current angle with the reference axis; The fourth step of calculating the difference between the initial angle before the rotation and the current angle after the rotation with respect to the identification point located in the focus area as the rotation angle of the code wheel / RTI > Each of the identification points having the same angular difference as the adjacent identification point, Wherein the focus area is one of the plurality of the code wheels when dividing the entire area of the code wheel into the same size, Wherein the number of identification points displayed on the code wheel is at least one more than the number of division of the entire area of the code wheel into a plurality of equal sizes. delete 12. The method according to claim 10 or 11, wherein the angle between the identification points is {360 占 ÷ number of identification points} and has the same angle. The rotation angle measuring method according to claim 10 or 11, wherein, in the third step, the distance of the identification point located in the focus area after rotation is calculated, and the unique number of the identification point matching with the calculated distance is grasped. 12. The method according to claim 10 or 11, wherein in the fourth step, the rotation angle is calculated by {360 DEG + (the current angle of the identification point existing in the focus area - the initial angle of the identification point existing in the focus area)} The rotation angle measuring method. 16. The rotation angle measuring method according to claim 15, wherein when the code wheel is made by one or more rotations, the number of rotations x 360 is added to the calculated rotation angle to calculate the final rotation angle.

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