KR101576169B1 - 3d 3d mouse and system comprising the same - Google Patents

Abstract

The present invention relates to a 3D mouse and a system including the same, and in accordance with one aspect of the present invention, there is provided a 3D mouse comprising a reference frame including at least three distance sensors, and a reflective frame movable relative to the reference frame, And each of the three distance sensors measures a distance between the reference frame and the reflection frame.

3D mouse, distance sensor

Description

3D MOUSE AND SYSTEM CONTAINING THE SAME

The present invention relates to a system including 3D mouse, and this, and more particularly, to a 3D mouse x axis rotation angle (θ _x), y-axis rotation angle (θ _y), and z-axis direction moving distance (z) The present invention relates to a 3D mouse and a system including the 3D mouse, which have high response speed and high accuracy, and can be easily implemented in hardware, by estimating with only three distance sensors and processing the estimation in a non-contact manner.

Since Douglas Engelbart devised while working for the Stanford Institute in the United States and patented the name "XY Position Indicator For a Display System" in 1970, the mouse has been adapted to a GUI (Graphical User Interface) environment such as Microsoft's Windows Has been widely used as a pointing device.

The first-generation mouse is based on mechanical working principles. There are two kinds of mechanically operating mice, one of which is a ball mouse. A ball mouse usually includes two rollers, which sense the horizontal and vertical movements of the mouse and calculate relative coordinate values. The other, on the other hand, is a mouse that includes two wheels instead of two rollers, which counts the number of times the LED light through a hole in the edge of the wheel is blocked, The vertical motion is detected and relative coordinate values are calculated.

These mechanical mice are being replaced by second generation mice, optical mice. There are many different types of optical mice. The biggest difference between the first generation mouse and the optical mouse is that they use image processing. The second-generation mouse has a black-and-white camera having a resolution of 18 × 18 on the bottom surface for the purpose of image processing, and estimates the moving direction of the mouse through the change in illuminance on the surface. Implementation of this principle is sometimes referred to as "optical flow".

However, the first generation mouse and the second generation mouse provide only two degrees of freedom (DOF), and only xy positioning is possible. Therefore, a new environment required by the current market, that is, a 3D web application, Dimensional game apparatuses and the like. This is the third generation mouse.

Mice classified as third-generation mice include public mice, 3D mice, and video mice, and these third-generation mice provide six DOFs. Here, 6 DOF may be x axis direction movement, y axis direction movement, z axis direction movement, x axis roll angle, y axis pitch angle, and z axis rotation angle (yaw angle) . In other words, a third generation mouse enables tracking of six movements in three dimensional space.

Typically, a public mouse equipped with an acceleration sensor and a gyro sensor estimates six parameter values corresponding to six DOFs using an extended Kalman process. These aerial mice have the advantage that they can be used without a desk-like support. On the other hand, 3D and video mice have advantages in terms of cost and sophistication. Of these, the video mouse estimates 6 DOF using a CCD camera having a resolution of 320 x 240. This is because the position of a mouse pad on which a special pattern is printed is deciphered through complicated image processing, Lt; / RTI > However, since the 3D mouse and the video mouse operate in a contact-type manner, they require a support for use, slow reaction speed, and have a disadvantage that foreign substances such as dust can be introduced.

To solve this problem, a non-contact type mouse that uses magnetic flux is developed. A Melexis mouse that uses magnetic flux includes a position sensor. This position sensor processes the position confirmation on the three-dimensional space in a noncontact manner, in particular, it operates in such a manner that the change values of the three components of the magnetic flux density (B _x , B _y , B _z ) are used. However, since the mouse using the magnetic flux is sensitive to the influence of the magnetic field, there is a problem that an inaccurate result can be obtained due to the influence of the magnetic field.

Therefore, it is urgent to develop a third-generation mouse that operates in a non-contact manner, has a high reaction speed and high accuracy, and is easy to implement.

SUMMARY OF THE INVENTION The present invention has been made to solve all the problems of the prior art described above.

It is still another object of the present invention to provide a 3D mouse and a system including the same, which are capable of detecting an x-axis rotation angle (? _X ), a y-axis rotation angle (? _Y ) (z) in the z-axis direction, thereby providing a fast response speed and high accuracy.

It is still another object of the present invention to provide a 3D mouse that is easy to implement in hardware.

Another object of the present invention is to implement a non-contact 3D mouse by grasping the movement of the mouse based on the relative movement between the reference frame and the reflection frame included in the 3D mouse.

In order to accomplish the above object, a representative structure of the present invention is as follows.

According to one aspect of the present invention, there is provided a display device comprising: a reference frame including at least three distance sensors; and a reflective frame movable relative to the reference frame, And a distance between the first mouse and the second mouse is measured.

In addition, other systems for implementing the present invention are provided.

According to the present invention, it is possible to realize a 3D mouse having a high reaction rate and high accuracy and a system including the 3D mouse.

According to the present invention, a 3D mouse which is easy to implement in hardware is provided.

According to the present invention, a non-contact type 3D mouse can be realized by grasping the movement of the mouse based on the relative movement between the reference frame and the reflection frame included in the 3D mouse, thereby realizing a 3D The mouse is achieved.

The following detailed description of the invention refers to the accompanying drawings, which illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with one embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly explained. In the drawings, like reference numerals refer to the same or similar functions throughout the several views.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention.

In the present specification, the term "mouse" is used as a representative example of the pointing device. However, since the technical idea of the present invention is implemented, the pointing device according to the present invention should not be limited to a mouse, Not only a mouse but also a remote controller (for example, a remote controller of a TV receiver, a remote controller of a DVD player, etc.) commonly referred to as a joystick, a pointing stick, a Wii remote, It should be imported.

[Preferred Embodiment of the Present Invention]

Complete configuration of 3D mouse

Fig. 1 is a diagram schematically showing main components of an internal structure of a 3D mouse 1 according to an embodiment of the present invention. Fig. 2 is a diagram showing an example of a system including the 3D mouse 1 shown in Fig. 1 Fig.

First, as shown in FIG. 1, a 3D mouse 1 according to an embodiment of the present invention may be configured to include two main components, that is, a reference frame 100 and a reflection frame 200 . The reference frame 100 is a component forming the bottom surface of the 3D mouse 1 and the reflection frame 200 is a component representing movement relative to the reference frame 100 according to a user's operation. In addition, the reference frame 100 may include one or more distance sensors.

2, a system including a 3D mouse 1 according to an embodiment of the present invention includes a reference frame 100 including n distance sensors, an operation processing unit 300, (400).

The operation principle of the 3D mouse 1 according to the present invention will be briefly described as follows. When at least one distance sensor included in the reference frame 100 irradiates light, it is reflected by the reflection frame 200 and returns to the reference frame 100. At this time, the at least one distance sensor senses the illuminance of the reflected light and converts it into an electrical signal. Since the electrical signal has a constant relationship with the distance between the distance sensor included in the reference frame 100 and the reflection frame 200, the distance sensor detects the distance between the reference frame 100 and the reflection frame 200 based on the electrical signal, It is possible to measure the distance between them. The measured values are transmitted to the operation processing unit 300. The operation processing unit 300 receives the x-axis rotation angle? _X , the y-axis rotation angle? _Y , and the z- The moving distance (height) can be grasped. The arithmetic processing by the arithmetic processing unit 300 will be described later in detail.

The x-axis rotation angle? _X , the y-axis rotation angle? _Y , and the z-axis movement distance (height) of the 3D mouse 1 are recognized by the operation processing unit 300, To the peripheral device such as a PC through the display device 400, and the peripheral device which receives the peripheral device can display the movement of the 3D mouse 1. [

Here, the communication module 400 performs a function of transmitting the output value from the operation processing unit 300 to the peripheral device. In general, the communication module 400 performs a function of enabling data transmission / reception to / from the operation processing unit 300. The communication module 400 may be a wireless communication module or other wired communication module employing a ZigBee communication method, an IRDA (InfraRed Data Association) method, an RF (Radio Frequency) communication method, a Bluetooth communication method, or the like.

Hereinafter, the configuration of the 3D mouse 1 according to various embodiments of the present invention and its operation principle will be described in detail.

First Embodiment

FIGS. 3, 4, and 5 are views showing the configurations of the reference frame 100 and the reflection frame 200 included in the 3D mouse 1 according to the first embodiment of the present invention.

3 and 4, three distance sensors 110, 111 and 112 may be included in the reference frame 100 of the 3D mouse 1 according to the first embodiment of the present invention.

Preferably, the three distance sensors 110, 111, and 112 may be triangular on the reference frame 100, and as described above, they may have a distance between the reference frame 100 and the reflective frame 200 at each point Can be performed. Specifically, the three distance sensors 110, 111, and 112 irradiate light toward the reflective frame 200, and determine the distance from the reflective frame 200 to the illuminance of the light reflected from the reflective frame 200 I'll do it.

For example, when the positions of the first distance sensor 110, the second distance sensor 111, and the third distance sensor 112 on the reference frame 100 are (x ₀ , y ₀ ), (x ₁ , y _1), (x _2, y ₂₎ and is represented by the coordinate type, such as, respectively, the distance to each distance sensor (110, 111, 112) is a reflecting frame (200 measurements), d _0, d _1, d ₂ , The mathematical model of the x-axis rotation angle? _X and the y-axis rotation angle? _Y of the 3D mouse 1 can be expressed by the following Equation 1.

_{f (θ x, θ y |} x 0, y 0, y 1, d 0, d 1, d 2) = d 1 - min (d 0, d 2) - (y 0 - y 1) tan (θ x ) -0.5x ₀ tan (| ? _Y |)

The solutions θ _x and θ _y of the equation (1) exist in the plane space of the equation (1), and satisfy the following equation (2).

_{f (θ x, θ y |} x 0, y 0, y 1, d 0, d 1, d 2) = 0

Using these equations (1) and (2), the estimated values of? _X and? _Y can be obtained. Each of the estimated values thus calculated can be found by the following Equations (3) and (4).

= tan ^-1((d ₁-(0.5｜d ₀-d ₂｜+min(d ₀,d ₂)))/｜y ₀-y ₁｜)

= tan ^-1 (( d ₁ - (0.5 | d ₀ - d ₂ | + min ( d ₀ , d ₂ )) / | y ₀ - y ₁ |

= tan ^-1((d ₀-d ₂)/x ₀)

= tan ^-1 (( d ₀ - d ₂ ) / x ₀ )

의 z 성분은 다음의 수학식 5 로 표현될 수 있다.On the other hand, the height of the 3D mouse 1, that is, the vector representing the position of the 3D mouse 1 with reference to the distance sensor 112 in Fig. 3

Can be expressed by the following equation (5).

= 0.5(d ₀+d ₂+(y ₀-y ₁)tan())

_{= 0.5 (d 0 + d 2} + (y 0 - y 1) tan ())

That is, the height of the 3D mouse 1 can be obtained by using the value of? _X obtained using Equation (3).

The system including the 3D mouse 1 according to an embodiment of the present invention is configured to receive the values d ₀ , d ₁ , d ₂ measured by the three distance sensors 110, 111, It is possible to grasp the x-axis rotation angle? _X , the y-axis rotation angle? _Y , and the z-axis movement distance (height)

6 and 7 are graphs showing the results of the simulation in which the x-axis rotation angle [theta] _x and the y-axis rotation angle [theta] _y are respectively estimated by the system including the 3D mouse 1 according to the first embodiment of the present invention Fig. In this simulation, the coordinates of the first distance sensor 110, the second distance sensor 111, and the third distance sensor 112 are (3 cm, 0 cm), (1.5 cm, -3 cm) ). In addition, the noise was set to have a normal distribution with an average value of 0 and a standard deviation of 0.2 cm. On the other hand, in the graphs of FIGS. 6 and 7, the unit of the vertical axis is degree. The unit of the horizontal axis is sec.

In the graphs of Figs. 6 and 7, the solid line is the sample value of the x-axis rotation angle [theta] _x and the y-axis rotation angle [theta] _y , respectively, and the dotted line is the simulation value for this sample value. That is, the solid line represents the actual x-axis rotation angle? _X and the y-axis rotation angle? _Y of the 3D mouse 1 and the dotted line represents the x-axis rotation of the 3D mouse 1 It can be said that the result is an estimation of the angle? _X and the y-axis rotation angle? _Y.

6 and 7, it can be seen that the estimated value coincides with the sample value, whereby the system including the 3D mouse 1 of the present invention can detect the x-axis rotation angle [theta] _x And the y-axis rotation angle? _Y are accurately estimated.

8 is a graph showing another simulation in which the x-axis rotation angle [theta] _x and the y-axis rotation angle [theta] _y are respectively estimated by the system including the 3D mouse 1 according to the first embodiment of the present invention Fig. In this simulation, the coordinates of the first distance sensor 110, the second distance sensor 111 and the third distance sensor 112 are (3 cm, 0 cm), (1.5 cm, -3 cm) ). In the graph shown, the horizontal axis represents the standard deviation of the noise. This noise has a Gaussian distribution, with an average value of 0, and a standard deviation value ranging from 0 cm to 0.45 cm. We performed 10,000 simulations per noise level. In the graph of FIG. 8, the unit of the vertical axis is also shown.

In the graph of Fig. 8, the solid line represents the estimated value of the y-axis rotation angle [theta] _y , and the dotted line represents the estimated value of the x-axis rotation angle [theta] _x .

As shown in Fig. 8, it can be seen that the estimated values of the x-axis rotation angle [theta] _x and the y-axis rotation angle [theta] _y also change with the standard deviation of the noise.

9 is a graph showing an estimate of the z-axis travel distance under the same conditions as the simulation described with reference to Fig. In the graph of Fig. 9, the unit of the vertical axis is distance (cm).

As shown in FIG. 9, it can be seen that the estimated values of the z-axis movement distance also vary with the standard deviation of the noise.

It can be seen from the graphs of FIGS. 6 to 9 that a system including the 3D mouse 1 according to the present invention obtains fairly accurate estimates even under the circumstances of exposure to noise.

Second Embodiment

10 is a diagram showing a configuration of a reference frame 100 included in the 3D mouse 1 according to the second embodiment of the present invention.

10, in the reference frame 100 of the 3D mouse 1 according to the second embodiment of the present invention, five distance sensors 110, 111, 112, 113 and 114 may be included have.

Four distance sensors 110, 112, 113, and 114 are arranged to form a quadrangle, and one distance sensor 111 may be disposed at the center point thereof. These five distance sensors 110, 111, 112, 113, and 114 also measure the distance to the reflective frame 200 at each point as described above.

For example, the first distance sensor 110, the second distance sensor 111, the third distance sensor 112, the fourth distance sensor 113, the fifth distance sensor 114, each of the position _{(x 0, y 0),} (x 1, y 1), (x 2, y 2), (x 3, y 3), (x 4, y 4) and can be represented by the coordinates of And d ₀ , d ₁ , d ₂ , d ₃ , and d ₄ are distances to the reflection frame 200 measured by the distance sensors 110, 111, 112, 113, and 114, respectively, 1) a mathematical model for the x-axis rotational angle (θ _x) and y-axis rotational angle (θ _y) of can be expressed by the following equation (6) the same.

_{f (θ x, θ y |} x 0, x 2, y 0, y 3, d 0, d 2, d 3, d 4) = -0.5 (d 3 + d 4) + min (d 0, d 2 _{) + (| y 0 - y} 3 |) tan (θ x) +0.5 (x 0 - x 2) tan (| θ y |)

This equation (6) the same year θ _x, θ _y in the case having the value of 0 is to present on a plane space of the equation (6), where 5 x expressed under the shaft rotation angle (θ _x) and three y-axis The equation for the rotation angle? _Y is satisfied.

First, the first x-axis rotation angle (θ _{x, 0} ) estimation value and the first y-axis rotation angle (θ _{y, 0} ) estimation value are expressed by the following Equation (7) and Equation (8).

= tan ^-1((d ₁-(0.5｜d ₀-d ₂｜+min(d ₀,d ₂)))/｜y ₀-y ₁｜)

= tan ^-1 (( d ₁ - (0.5 | d ₀ - d ₂ | + min ( d ₀ , d ₂ )) / | y ₀ - y ₁ |

= tan ^-1((d ₀-d ₂)/｜x ₀-x ₂｜)

= tan ^-1 (( d ₀ - d ₂ ) / | x ₀ - x ₂ |)

On the other hand, the second x-axis rotation angle (θ _{x, 1} ) estimation value and the second y-axis rotation angle (θ _{y, 1} ) estimation value are expressed by the following equations (9) and (10).

= tan ^-1((d ₃-d ₀)/｜y ₀-y ₃｜)

= tan ^-1 (( d ₃ - d ₀ ) / | y ₀ - y ₃ |)

= tan ^-1((d ₃-d ₄)/｜x ₃-x ₄｜)

= tan ^-1 (( d ₃ - d ₄ ) / | x ₃ - x ₄ |)

The estimates of the third x-axis rotation angle (? _{X, 2} ) and the fourth x-axis rotation angle (? _{X, 3} ) are expressed by the following equations (11) and (12), respectively.

= tan ^-1((d ₄-d ₂)/｜y ₂-y ₄｜)

_{^{= Tan -1 ((d 4 -}} d 2) / | y 2 - y 4 |)

= tan ^-1((0.5(d ₃+d ₄)-d ₁)/｜y ₁-y ₃｜)

^{= Tan -1 ((0.5 (d} 3 + d 4) - d 1) / | y 1 - y 3 |)

On the other hand, the fifth x-axis rotation angle? _X estimation value can be obtained using Equations (7), (9), (11), and (12).

=(+++)/4

= (+++) / 4

The fifth x-axis rotation angle [theta] _x obtained by Expression (13) becomes the x-axis rotation angle of the 3D mouse 1. [

On the other hand, using Equations (8) and (10), a third y-axis rotation angle ( _{y y} ) estimation value can be obtained, which is expressed by the following Equation (14).

=(+)/2

= (+) / 2

The third y-axis rotation angle? _Y obtained by the expression (14) becomes the y-axis rotation angle of the 3D mouse 1.

The system including the 3D mouse 1 according to the present invention has the values d ₀ , d ₁ , d ₂ , d ₃ , and d ₄ measured by the five distance sensors 110, 111, 112, through a _fourth rotating x-axis of 3D mouse (1) is able to do determine the angle (θ _x) and y-axis rotational angle (θ _y), z-axis direction movement distance (H) is the first embodiment of the present invention; So that it can be measured in the same manner as described above.

11 is a graph showing the result of a simulation in which the x-axis rotation angle [theta] _x and the y-axis rotation angle [theta] _y are respectively estimated by the system including the 3D mouse 1 according to the second embodiment of the present invention to be. In this simulation, the coordinates of the first distance sensor 110, the second distance sensor 111, the third distance sensor 112, the fourth distance sensor 113, and the fifth distance sensor 114 are (3 cm, 0 cm), (1.5 cm, -1.5 cm), (0 cm, 0 cm), (3 cm, -3 cm), (0 cm, -3 cm). In the graph shown, the horizontal axis represents the standard deviation of the noise. This noise has a Gaussian distribution, with an average value of 0 and a standard deviation of 0 to 0.45 cm. We performed 10,000 simulations per noise level. On the other hand, in the graph of FIG. 11, the unit of the vertical axis is also shown.

In the graph of Fig. 11, a solid line represents an estimated value of the y-axis rotational angle? _Y , and a dotted line represents an estimated value of the x-axis rotational angle? _X.

As shown in Fig. 11, it can be seen that the estimated values of the x-axis rotation angle? _X and the y-axis rotation angle? _Y also change together with the standard deviation of the noise. It can also be seen that more accurate estimates can be obtained than in the simulations described with reference to the graph of FIG. 8, that is, simulations using three distance sensors. As a result, it can be seen that the more accurate the angle of rotation or the positional change of the mouse 1 becomes, the more the number of distance sensors increases.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Therefore, the spirit of the present invention should not be construed as being limited to the above-described embodiments, and all of the equivalents or equivalents of the claims, as well as the following claims, I will say.

FIG. 1 is a diagram schematically illustrating main components of an internal configuration of a 3D mouse according to an embodiment of the present invention.

Fig. 2 is a diagram showing an example of a system including the 3D mouse shown in Fig. 1. Fig.

FIGS. 3, 4, and 5 are views showing the configuration of a reference frame and a reflection frame included in the 3D mouse according to the first embodiment of the present invention.

6 to 9 are graphs showing simulation results of a 3D mouse according to the first embodiment of the present invention.

10 is a diagram illustrating a configuration of a reference frame included in a 3D mouse according to a second embodiment of the present invention.

11 is a graph showing simulation results of a 3D mouse according to the second embodiment of the present invention.

Claims (9)

A system comprising a 3D mouse, In the 3D mouse, A reference frame comprising at least three distance sensors, and A reflective frame movable relative to the reference frame, each of the at least three distance sensors measuring a distance between the reference frame and the reflective frame, / RTI > The system comprises: An arithmetic processing unit for calculating an x-axis rotation angle (? _X ) and a y-axis rotation angle (? _Y ) of the 3D mouse on the basis of the measured distance; Further calculations - ≪ / RTI > The method according to claim 1, Wherein at least one of the at least three distance sensors measures the distance between the reference frame and the reflective frame based on illuminance of light reflected after illuminating the reflective frame. delete The method according to claim 1, The x-axis rotational angle (θ _x) and rotation angle (θ _y) the y-axis, _{f (θ x, θ y |} x 0, y 0, y 1, d 0, d 1, d 2) = d 1 - min (d 0, d 2) - (y 0 - y 1) tan (θ x ) -0.5x ₀ tan (| ? _Y |), and _{f (θ x, θ y |} x 0, y 0, y 1, d 0, d 1, d 2) = 0 (X ₀ , y ₀ ), (x ₁ , y ₁ ), and (x ₂ , y ₂ ) are position coordinates of three distance sensors among the at least three distance sensors , d ₀ , d ₁ , and d ₂ are the distances between the reference frame and the reflection frame measured by the three distance sensors - Lt; / RTI > 5. The method of claim 4, The x-axis rotational angle (θ _x) and rotation angle (θ _y) the y-axis,

= tan ^-1 (( d ₁ - (0.5 | d ₀ - d ₂ | + min ( d ₀ , d ₂ )) / y ₀ - y ₁ |

= tan ^-1 (( d ₀ - d ₂ ) / x ₀ ) ≪ / RTI > The method according to claim 1, Wherein the reference frame further comprises at least two distance sensors, The x-axis rotational angle (θ _x) and rotation angle (θ _y) the y-axis, _{f (θ x, θ y |} x 0, x 2, y 0, y 3, d 0, d 2, d 3, d 4) = -0.5 (d 3 + d 4) + min (d 0, d 2 _{) + (| y 0 - y} 3 |) tan (θ x) +0.5 (x 0 - x 2) tan (| θ y |), and _{f (θ x, θ y |} x 0, x 2, y 0, y 3, d 0, d 2, d 3, d 4) = 0 The one that is calculated from the equation - _{where, (x 0, y 0)} , (x 1, y 1), (x 2, y 2), (x 3, y 3), and (x _4, y ₄₎ Wherein d ₀ , d ₁ , d ₂ , d ₃ , and d ₄ are the position coordinates of the five distance sensors among the at least five distance sensors, Distance - Lt; / RTI > The method according to claim 6, The x-axis rotational angle (θ _x) and rotation angle (θ _y) the y-axis,

= (

+

+

+

) / 4, and

= (

+

)/2 Lt; / RTI > < RTI ID =

= tan ^-1 (( d ₁ - (0.5 | d ₀ - d ₂ | + min ( d ₀ , d ₂ ))) / | y ₀ - y ₁ |

= tan ^-1 (( d ₃ - d ₀ ) / | y ₀ - y ₃ |),

_{^{= Tan -1 ((d 4 -}} d 2) / | y 2 - y 4 |),

= tan ^-1 ((0.5 ( d ₃ + d ₄ ) - d ₁ ) / | y ₁ - y ₃ |

= tan ^-1 (( d ₀ - d ₂ ) / x ₀ - x ₂ |), and

= tan ^-1 (( d ₃ - d ₄ ) / | x ₃ - x ₄ |) - Lt; / RTI > delete The method according to claim 1, The z-axis moving distance z

_{= 0.5 (d 0 + d 2} + (y 0 - y 1) tan (

)) (X ₀ , y ₀ ), (x ₁ , y ₁ ), and (x ₂ , y ₂ ) are the position coordinates of three distance sensors among the at least three distance sensors, and d ₀ , d ₁ , and d ₂ are the distances between the reference frame and the reflection frame measured by the three distance sensors - Lt; / RTI >

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