阅读说明：本技术 基于硬度检测的自动雕刻控制系统及控制方法 (Automatic carving control system and control method based on hardness detection ) 是由 张亚龙 王美丽 高华 沈文跃 刘畅 葛胜利 夏乾坤 于 2020-12-23 设计创作，主要内容包括：本发明属于雕刻技术领域,具体涉及一种基于硬度检测的自动雕刻控制系统及控制方法,其中基于硬度检测的自动雕刻控制系统包括：工控机,以及与工控机电性连接的硬度计和雕刻机；所述工控机适于根据所要雕刻的材料选择相应模型,以确定材料表面检测点的分布；所述工控机适于根据检测点控制所述硬度计检测材料表面各检测点的硬度；所述工控机适于根据各检测点的硬度匹配各检测点的雕刻速度；所述工控机适于根据各检测点的雕刻速度控制所述雕刻机对材料进行雕刻,在雕刻行业逐步取代手工雕刻实现自动化生产,减轻工人的劳动强度,提高生产效率和雕刻成功率。(The invention belongs to the technical field of engraving, and particularly relates to an automatic engraving control system and a control method based on hardness detection, wherein the automatic engraving control system based on hardness detection comprises: the industrial personal computer, and the hardness tester and the engraving machine which are electrically connected with the industrial personal computer; the industrial personal computer is suitable for selecting a corresponding model according to the material to be carved so as to determine the distribution of the detection points on the surface of the material; the industrial personal computer is suitable for controlling the hardness of each detection point on the surface of the detection material of the hardness meter according to the detection points; the industrial personal computer is suitable for matching the engraving speed of each detection point according to the hardness of each detection point; the industrial personal computer is suitable for controlling the carving machine to carve the material according to the carving speed of each detection point, automatic production is realized by gradually replacing manual carving in the carving industry, the labor intensity of workers is reduced, and the production efficiency and the carving success rate are improved.)

1. An automatic carving control system based on hardness detection is characterized by comprising:

the industrial personal computer, and the hardness tester and the engraving machine which are electrically connected with the industrial personal computer;

the industrial personal computer is suitable for selecting a corresponding model according to the object of the corresponding material so as to determine the distribution of the detection points on the surface of the current material;

the industrial personal computer is suitable for controlling the hardness meter to detect the hardness of each detection point on the surface of the current material according to the detection points;

the industrial personal computer is suitable for matching the engraving speed of each detection point according to the hardness of each detection point;

the industrial personal computer is suitable for controlling the carving machine to carve the current material according to the carving speed of each detection point.

2. The automatic engraving control system based on hardness detection according to claim 1,

the industrial personal computer is suitable for controlling the probe in the hardness tester to probe downwards so as to detect the hardness of each detection point on the surface of the current material.

3. The automatic engraving control system based on hardness detection according to claim 2,

the industrial personal computer is suitable for being connected with the hardness tester through an RS232 interface so as to receive hardness data of each detection point detected by the hardness tester;

and the PCI module in the industrial personal computer is suitable for converting the hardness data of each detection point detected by the hardness tester and storing the converted hardness data.

4. The automatic engraving control system based on hardness detection according to claim 3,

and the display module in the industrial personal computer is suitable for displaying the hardness of each detection point.

5. The automatic engraving control system based on hardness detection according to claim 4,

and the display module in the industrial personal computer is suitable for displaying the engraving speed of each detection point.

6. The automatic engraving control system based on hardness detection according to claim 5,

the industrial personal computer is suitable for matching the engraving speed of each detection point according to the hardness of each detection point, namely

Probe lower probe of hardness testerMeasuring the hardness (X) of the current detection point of the current material₀，Y₀，P₀)；

Recording and summarizing hardness data of each detection point;

setting a fusion matrix W to perform matching processing on the hardness data of each detection point, and matching the hardness and the integral hardness of a single detection point with the engraving speed;

the engraving speed is compensated through the speed compensation parameter Q, so that the engraving is stably carried out;

when the average value of the whole engraving speed of the current material is lower than the engraving speed of a single detection point, multiplying the engraving speed of the current position by a compensation parameter Q to obtain the required engraving speed; otherwise the engraving speed remains unchanged.

7. The automatic engraving control system based on hardness detection according to claim 6,

the fusion matrix W is:

wherein (X)_n，Y_n) The coordinate position of the (n-1) th detection point is obtained; p_nThe hardness value of the (n-1) th detection point is obtained;

the hardness of a single detection point is matched with the processing speed:

the overall hardness is matched with the engraving speed:

8. the automatic engraving control system based on hardness detection according to claim 7,

said pass speed compensation parameter Q, compensating the engraving speed, i.e.

The total distance of the integral compensation generating the positioning precision within the preset time is S_e；

The distance that has been compensated currently is s_f，s_fIs 0, s for each compensation of one unit time period_fTo add the current compensation value:

wherein S is₁，S₂，S₃Respectively is a uniform speed section distance, an acceleration section distance, a deceleration section distance and a deceleration section distance S₃≥S_{3_max}(ii) a S is the total distance of compensation;

maximum deceleration distance s_{3_max}Comprises the following steps:

wherein a is centripetal acceleration; v is the velocity of the splice;

the velocity of the joint is v₀,v₁,v₂…v_nThen, in the ith segment:

acquiring i +1 section excessive speed v_i+1；

If S_{3_i_max}≤S₃Optimizing the speed by adopting an S-shaped curve acceleration and deceleration algorithm;

if S_{3_i_max}>S₃And v is_i>v_i+1The engraving speed is adjusted toIf v is_i<v_i+1The engraving speed is adjusted tos_iAccelerating and decelerating for curves;

judging whether the centripetal acceleration of the curve is greater than a given threshold value: a is_N≥T；

If the number of the vertices is larger than the given threshold, in the current period, selecting the vertices of n original paths as control vertices of a Nurbs curve, and simultaneously setting a weight factor of each vertex, so that the k times Nurbs curve is as follows:

wherein, w_i(i-0, 1, … n) is a weight factor, and w_i≥0；p_iRepresenting a control vertex; n is a radical of_i,k(u) is a k-th order canonical B-spline basis function; the recursion formula of the B spline basis function is as follows:

and the obtained fitted interpolation contour meets the requirement of the engraving machine on high-precision interpolation.

9. An automatic carving control method based on hardness detection is characterized by comprising the following steps:

detecting the hardness of each detection point on the surface of the current material;

matching the engraving speed of each detection point according to the hardness of each detection point; and

and the machine engraves the current material according to the engraving speed of each detection point.

10. The automatic engraving control method based on hardness detection according to claim 9,

the automatic carving control method based on hardness detection is suitable for carving the current material by adopting the automatic carving control system based on hardness detection according to any one of claims 1-8.

Technical Field

The invention belongs to the technical field of automatic engraving, and particularly relates to an automatic engraving control system and method based on hardness detection.

Background

The carving art is one of the traditional art types of China, and the application range is very wide. With the improvement of the appreciation level of people, some handmade artworks which are complex to process and delicate to carve are more and more favored by consumers.

At present, in the traditional hand engraving industry, a great deal of effort is needed for an engraver to produce the product with exquisite modeling. Therefore, the traditional manual engraving process is far from meeting the market demand. In recent years, carving machines appearing in domestic markets, Jiangsu 'Ruosu' and Shanghai 'woodpeckers' have certain markets in China. However, these engravers have some defects in the complicated engraving process, and have the following disadvantages: the material cannot be processed according to the characteristics of the texture of the material, namely different materials and the hardness degrees of different parts; automation cannot be completely realized in the processing process, and the display interface is not concise; errors are easy to generate when detail is engraved.

Therefore, it is necessary to design a new automatic engraving control system and control method based on hardness detection based on the above technical problems.

Disclosure of Invention

The invention aims to provide an automatic engraving control system and a control method based on hardness detection.

In order to solve the above technical problem, the present invention provides an automatic engraving control system based on hardness detection, comprising:

the industrial personal computer, and the hardness tester and the engraving machine which are electrically connected with the industrial personal computer;

the industrial personal computer is suitable for selecting a corresponding model according to the object of the corresponding material so as to determine the distribution of the detection points on the surface of the current material;

the industrial personal computer is suitable for controlling the hardness meter to detect the hardness of each detection point on the surface of the current material according to the detection points;

the industrial personal computer is suitable for matching the engraving speed of each detection point according to the hardness of each detection point;

the industrial personal computer is suitable for controlling the carving machine to carve the current material according to the carving speed of each detection point.

Further, the industrial personal computer is suitable for controlling a probe in the hardness tester to probe downwards so as to detect the hardness of each detection point on the surface of the current material.

Further, the industrial personal computer is suitable for being connected with the hardness tester through an RS232 interface so as to receive hardness data of each detection point detected by the hardness tester;

and the PCI module in the industrial personal computer is suitable for converting the hardness data of each detection point detected by the hardness tester and storing the converted hardness data.

Further, a display module in the industrial personal computer is suitable for displaying the hardness of each detection point.

Further, a display module in the industrial personal computer is suitable for displaying the engraving speed of each detection point.

Further, the industrial personal computer is adapted to match the engraving speed of the detection points according to the hardness of the detection points, i.e. the industrial personal computer

Probing down with a hardness meter probe to measure the hardness (X) of the current detection point of the current material₀，Y₀，P₀)；

Recording and summarizing hardness data of each detection point;

setting a fusion matrix W to perform matching processing on the hardness data of each detection point, and matching the hardness and the integral hardness of a single detection point with the engraving speed;

the engraving speed is compensated through the speed compensation parameter Q, so that the engraving is stably carried out;

when the average value of the whole engraving speed of the current material is lower than the engraving speed of a single detection point, multiplying the engraving speed of the current position by a compensation parameter Q to obtain the required engraving speed; otherwise the engraving speed remains unchanged.

Further, the fusion matrix W is:

wherein (X)_n，Y_n) The coordinate position of the (n-1) th detection point is obtained; p_nThe hardness value of the (n-1) th detection point is obtained;

the hardness of a single detection point is matched with the processing speed:

the overall hardness is matched with the engraving speed:

further, said pass speed compensation parameter Q, compensates the engraving speed, i.e.

The total distance of the integral compensation generating the positioning precision within the preset time is S_e；

The distance that has been compensated currently is s_f，s_fIs 0, s for each compensation of one unit time period_fTo add the current compensation value:

wherein S is₁，S₂，S₃Respectively is a uniform speed section distance, an acceleration section distance, a deceleration section distance and a deceleration section distance S₃≥S_{3_max}(ii) a S is the total distance of compensation;

maximum deceleration distance s_{3_max}Comprises the following steps:

wherein a is centripetal acceleration; v is the velocity of the splice;

the velocity of the joint is v₀,v₁,v₂…v_nThen, in the ith segment:

acquiring i +1 section excessive speed v_i+1；

If S_{3_i_max}≤S₃Optimizing the speed by adopting an S-shaped curve acceleration and deceleration algorithm;

if S_{3_i_max}>S₃And v is_i>v_i+1The engraving speed is adjusted toIf v is_i<v_i+1The engraving speed is adjusted tos_iAccelerating and decelerating for curves;

judging whether the centripetal acceleration of the curve is greater than a given threshold value: a is_N≥T；

If the number of the vertices is larger than the given threshold, in the current period, selecting the vertices of n original paths as control vertices of a Nurbs curve, and simultaneously setting a weight factor of each vertex, so that the k times Nurbs curve is as follows:

wherein, w_i(i-0, 1, … n) is a weight factor, and w_i≥0；p_iRepresenting a control vertex; n is a radical of_i,k(u) is a k-th order canonical B-spline basis function; the recursion formula of the B spline basis function is as follows:

and the obtained fitted interpolation contour meets the requirement of the engraving machine on high-precision interpolation.

On the other hand, the invention also provides an automatic engraving control method based on hardness detection, which comprises the following steps:

detecting the hardness of each detection point on the surface of the current material;

matching the engraving speed of each detection point according to the hardness of each detection point; and

and the machine engraves the current material according to the engraving speed of each detection point.

Further, the automatic carving control method based on hardness detection is suitable for carving the current material by adopting the automatic carving control system based on hardness detection.

The industrial personal computer, the hardness tester and the engraving machine are electrically connected with the industrial personal computer; the industrial personal computer is suitable for selecting corresponding models according to objects made of different materials so as to determine the distribution of the detection points on the surface of the current material; the industrial personal computer is suitable for controlling the hardness meter to detect the hardness of each detection point on the surface of the current material according to the detection points; the industrial personal computer is suitable for matching the engraving speed of each detection point according to the hardness of each detection point; the industrial personal computer is suitable for controlling the carving machine to carve the current material according to the carving speed of each detection point, and the industrial personal computer gradually replaces manual carving in the handicraft carving industry to realize automatic production, so that the labor intensity of workers is reduced, and the production efficiency and the carving success rate are improved.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.

In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic block diagram of an automatic engraving control system based on hardness detection according to the present invention;

FIG. 2 is a control flow chart of an automatic engraving control system based on hardness detection according to the present invention;

FIG. 3 is a schematic illustration of a hardness testing interface according to the present invention;

fig. 4 is a schematic connection diagram of an automatic engraving control system based on hardness detection according to the present invention.

Detailed Description

To make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

FIG. 1 is a schematic block diagram of an automatic engraving control system based on hardness detection according to the present invention;

fig. 2 is a control flow chart of an automatic engraving control system based on hardness detection according to the present invention.

As shown in fig. 1 and 2, the present embodiment 1 provides an automatic engraving control system based on hardness detection, including: the industrial personal computer, and the hardness tester and the engraving machine which are electrically connected with the industrial personal computer; the industrial personal computer is suitable for selecting corresponding models according to objects made of different materials (selecting corresponding models according to the shapes of the objects made of different materials) so as to determine the distribution of the detection points on the surface of the current material; the industrial personal computer is suitable for controlling the hardness meter to detect the hardness of each detection point on the surface of the current material according to the detection points; the industrial personal computer is suitable for matching the engraving speed of each detection point according to the hardness of each detection point; the industrial personal computer is suitable for controlling the carving machine to carve the current material according to the carving speed of each detection point, and the industrial personal computer gradually replaces manual carving in the handicraft carving industry to realize automatic production, so that the labor intensity of workers is reduced, and the production efficiency and the carving success rate are improved.

In this embodiment, the industrial personal computer is adapted to control the probe in the hardness tester to probe the hardness of each detection point on the surface of the current material.

In this embodiment, the industrial personal computer is adapted to be connected with the hardness tester through an RS232 interface to receive hardness data of each detection point detected by the hardness tester; the PCI module in the industrial personal computer is suitable for converting the hardness data of each detection point detected by the hardness tester (converting the hardness data into a format which can be labored by the industrial personal computer) and storing the converted hardness data.

In this embodiment, the industrial personal computer controls the hardness tester to detect the hardness of each detection point on the surface of the current material one by one, for example, all the detection points are obtained according to the current material model, all the detection points are marked (for example, based on the number of each detection point), hardness detection is performed on all the detection points one by one (in the detection process, judgment is performed after each detection point is detected, and detection is continued when undetected detection points exist), and after the hardness detection of all the detection points is completed, the industrial personal computer controls the probe in the hardness tester to return to the original position.

Fig. 3 is a schematic view of a hardness testing interface according to the present invention.

As shown in fig. 3, in this embodiment, a display module (the display module may be a touch display screen for facilitating human-computer interaction) in the industrial personal computer is adapted to display the hardness of each detection point; the display module is suitable for displaying a control interface; according to the point positions (the positions of the detection points) detected by the hardness meter, data (hardness data of each detection point is displayed) is marked and recorded on the planar development drawing of the carving area of the control interface, and the data can be inquired on the control interface (a display module), so that the hardness of each detection point of the current material can be conveniently and visually known.

In this embodiment, the display module in the industrial personal computer is adapted to display the engraving speed of each detection point; as shown in table 1, the corresponding engraving speed (cutting speed) can be matched according to the hardness, the engraving speed of one detection point can be matched with the hardness of one detection point, the cutting speed of the current position (engraving speed of the current detection point) is displayed on the display module, the engraving speed of each detection point of the current material can be conveniently and visually known, and the data (engraving speed of each detection point) is led into the engraving machine, so that the success rate of engraving the current material (the X axis, the Y axis and the Z axis of the engraving machine are controlled to control engraving) by the engraving machine is improved.

Table 1: hardness and cutting speed corresponding table

In the embodiment, for a large-area carving area, the carving speed is adjusted according to the hardness of the current material, and the carving speed is preset according to the hardness of the current material at each position in the carving area where the cutter needs to be lowered; and aiming at the small-area carving area, performing fusion calculation on the speed of the whole carving surface based on a matrix algorithm to obtain the average carving speed, and carving.

In this embodiment, the display module in the industrial personal computer can be logically divided according to the relevant properties and importance; the user interface (display module) can conveniently process various affairs, and can simply make the system (automatic carving control system based on hardness detection) have the expected function, the automatic carving control system based on hardness detection has higher real-time performance, especially when the carving machine works, when the user requires the machine such as the carving machine to stop processing immediately or when the machine tool (carving machine) breaks down, the corresponding button of the user interface is operated, the automatic carving control system based on hardness detection can respond quickly; the user interface is reliable to use, the user can be guaranteed to use the system correctly and reliably, and the safety of related programs and data is guaranteed.

Fig. 4 is a schematic connection diagram of an automatic engraving control system based on hardness detection according to the present invention.

As shown in fig. 4, in the present embodiment, the keyboard in the industrial personal computer enables the user to perform manual control and the like on the automatic engraving control system based on hardness detection; the industrial personal computer can control the engraving of the X axis, the Y axis and the Z axis of the engraving machine through the touch controller.

In the embodiment, the industrial personal computer is suitable for matching the engraving speed of each detection point according to the hardness of each detection point, namely, the hardness tester probe downwards probes, and measuring the hardness value (X) of the current detection point (current position) of the current material₀，Y₀，P₀) (ii) a Recording and summarizing hardness data of each detection point; defining a fusion matrix W to perform matching processing on the hardness data of each detection point, and matching the hardness and the overall hardness (the overall hardness of the current material, namely the hardness of each detection point) of a single detection point with the engraving speed; the engraving speed is compensated through the speed compensation parameter Q, so that the engraving can be stably carried out; when the average value of the whole engraving speed of the current material is lower than the engraving speed of a single detection point, multiplying the engraving speed of the current position by a compensation parameter Q to obtain the required engraving speed; otherwise, the engraving speed is kept unchanged, the value of the speed compensation parameter Q is in the range of 0.7-1.5, and the generated engraving effect is relatively good.

In this embodiment, the fusion matrix W is:

wherein (X)_n，Y_n) The coordinate position of the (n-1) th detection point is obtained; p_nThe hardness value of the (n-1) th detection point is obtained; hardness data (X) of each test point_n，Y_n，P_n) Importing a fusion matrix W;

the hardness of a single detection point is matched with the processing speed:

the overall hardness is matched with the engraving speed:M/S is meter/second

In the embodiment, the speed compensation algorithm is designed according to the positioning error of the engraving machine, and the effect of zero speed-acceleration-uniform speed-deceleration-zero speed is expected to be generated in multiple sections in consideration of the speed; the total distance for compensating the engraving speed by the speed compensation parameter Q, namely, the speed of the engraving machine is assumed to have deviation, so that the total distance for generating the integral compensation of the positioning precision in a preset time (a period of time) is S_eI.e. the total target compensation value over a period of time;

the distance that has been compensated currently is s_f，s_fIs 0, s for each compensation of one unit time period_fTo add the current compensation value:

wherein S is₁，S₂，S₃Respectively is a uniform speed section distance, an acceleration section distance, a deceleration section distance and a deceleration section distance S₃≥S_{3_max}To ensure that the subsequent engraving speed is not involved in the current processing section; s is the total distance of compensation;

maximum deceleration distance s_{3_max}Comprises the following steps:

wherein a is centripetal acceleration; v is the velocity of the splice;

the velocity of the joint is v₀,v₁,v₂…v_nThen, in the ith segment:

s_iaccelerating and decelerating for curves;

acquiring i +1 section excessive speed v_i+1；

If S_{3_i_max}≤S₃Optimizing the speed by adopting an S-shaped curve acceleration and deceleration algorithm;

if S_{3_i_max}>S₃And v is_i>v_i+1The engraving speed is adjusted toIf v is_i<v_i+1The engraving speed is adjusted to

In order to avoid the problem that the acceleration of the system cannot meet the given speed change caused by overlarge curvature radius in the cutting process of a curve path, in the processing process of the curve, if acceleration and deceleration are not carried out on a linear part, processing is required to be carried out at a lower speed, meanwhile, a linear section has a first-order discontinuity characteristic, and the overshoot phenomenon caused cannot guarantee the processing quality and the accuracy, so that high-precision interpolation is realized by adopting a NuRBS curve fitting mode: judging whether the centripetal acceleration of the curve is greater than a given threshold value: a is_N≥T；

If the number of the vertices is larger than the given threshold, in the current period, selecting the vertices of n original paths as control vertices of a Nurbs curve, and simultaneously setting a weight factor of each vertex, so that the k times Nurbs curve is as follows:

wherein, w_i(i-0, 1, … n) is a weight factor, and w_i≥0；p_iRepresenting a control vertex; n is a radical of_i,k(u) is a k-order normalized B-spline basis function determined by the node vector u; the recursion formula of the B spline basis function is as follows:

the curve interpolation has contour errors, so that the requirement of the engraving machine on high-precision interpolation can be met only by calculating the error between the fitted interpolated contour and the real contour within a certain interval range.

Example 2

On the basis of embodiment 1, this embodiment 2 further provides an automatic engraving control method based on hardness detection, including: detecting the hardness of each detection point on the surface of the current material; matching the engraving speed of each detection point according to the hardness of each detection point; and the machine engraves the current material according to the engraving speed of each detection point.

In the embodiment, the automatic engraving control method based on hardness detection is suitable for engraving the current material by adopting the automatic engraving control system based on hardness detection in the embodiment 1; the method for detecting the hardness of each detection point on the surface of the current material, matching the engraving speed of each detection point according to the hardness of each detection point, and engraving the current material according to the engraving speed of each detection point is described in detail in embodiment 1 and is not repeated in this embodiment.

In this embodiment, the hardness detection automatic engraving control method further includes: displaying the hardness of each detection point and displaying the engraving speed of each detection point.

In conclusion, the industrial personal computer, the hardness tester and the engraving machine are electrically connected with the industrial personal computer; the industrial personal computer is suitable for selecting a corresponding model according to the current material so as to determine the distribution of the detection points on the surface of the current material; the industrial personal computer is suitable for controlling the hardness meter to detect the hardness of each detection point on the surface of the current material according to the detection points; the industrial personal computer is suitable for matching the engraving speed of each detection point according to the hardness of each detection point; the industrial personal computer is suitable for controlling the carving machine to carve the current material according to the carving speed of each detection point, and the automatic production is realized by gradually replacing manual carving in the ceramic handicraft carving industry, so that the labor intensity of workers is reduced, and the production efficiency and the carving success rate are improved.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. The above-described embodiments of the apparatus are merely illustrative, and for example, the division of the units is only one logical division, and there may be other divisions when actually implemented, and for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection of devices or units through some communication interfaces, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.

In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.