阅读说明：本技术 等离子切割机的切割头控制方法及系统 (Cutting head control method and system of plasma cutting machine ) 是由 刘景景 刘传洋 方曙东 孙佐 束人龙 陈林 于 2020-05-29 设计创作，主要内容包括：本发明提供了一种等离子切割机的切割头控制方法及系统,基于切割任务表,确定子路径函数和子路径图的角点集合；通过选择距离距切割头最近的角点,来确定第一个进行切割的切割图案,再确定第1个进行切割的切割图案中所有子路径图的切割顺序,并基于切割顺序得到切割图案的切割策略；将更新后的切割头初始位置作为下个切割图案的切割头的位置,以此类推,就可得到切割任务表中所有切割图案的切割策略,等离子切割机即可按照i值从小至大对切割图案进行切割,且每个切割图案中的子路径图按照对应的切割策略进行切割。使切割头无需进行复位操作后再对下个切割图案进行切割,进而缩短了总切割时间。(The invention provides a cutting head control method and a cutting head control system of a plasma cutting machine, which are characterized in that a sub-path function and an angular point set of a sub-path graph are determined based on a cutting task table; determining a first cutting pattern for cutting by selecting the corner point closest to the cutting head, determining the cutting sequence of all sub-path diagrams in the 1 st cutting pattern for cutting, and obtaining a cutting strategy of the cutting pattern based on the cutting sequence; and taking the updated initial position of the cutting head as the position of the cutting head of the next cutting pattern, and so on to obtain the cutting strategies of all the cutting patterns in the cutting task table, wherein the plasma cutting machine can cut the cutting patterns from small to large according to the value i, and the sub-path diagram in each cutting pattern is cut according to the corresponding cutting strategy. The cutting head is enabled to cut the next cutting pattern after reset operation is not needed, and then the total cutting time is shortened.)

1. A cutting head control method of a plasma cutting machine, characterized by comprising:

s1, acquiring an initial position of a cutting head and a cutting task table, wherein the cutting task table comprises a cutting pattern set, the number of each cutting pattern and a sub-path diagram set corresponding to each cutting pattern, setting a first cycle parameter i, and initializing the first cycle parameter to make i equal to 1;

acquiring a sub-path function corresponding to the sub-path diagram based on the sub-path diagram;

acquiring a corner set of the sub-path graph based on the sub-path graph; obtaining a corner set T ═ V corresponding to all cutting patterns₁，V₂，…}；

S2, screening the corner points closest to the initial position of the cutting head from the T to serve as initial selection corner points; obtaining the cutting pattern corresponding to the initially selected angular point as the ith cutting pattern for cutting, and determining the corresponding quantity Q in the cutting task table_i；

S3, determining the cutting sequence of all sub-path graphs in the ith cutting pattern to be cut, and obtaining the cutting strategy of the cutting pattern based on the cutting sequence; updating the initial position of the cutting head and deleting the corner point subset V corresponding to the ith cutting pattern from the T based on the position of the cutting head after executing the cutting strategy;

and S4, repeatedly executing S2-S3, and enabling i to be i +1 until the cutting strategies of all the cutting patterns are obtained, and arranging the cutting strategies according to the small value and the large value of i to obtain the total cutting strategy.

2. The method of claim 1, wherein the obtaining the sub-path function corresponding to the sub-path diagram based on the sub-path diagram comprises:

generating a positioning coordinate system based on the cutting surface of the workpiece to be machined;

based on the positioning coordinate system, acquiring a sub-path function F ═ F corresponding to the sub-path graph₁(x)，f₂(x),…}。

3. The cutting head control method of a plasma cutting machine according to claim 1, wherein the S3 determines the cutting sequence of all sub-path diagrams in the ith cutting pattern to be cut, and obtains the cutting strategy of the cutting pattern based on the cutting sequence; updating the initial position of the cutting head and deleting the corner subset V corresponding to the ith cutting pattern from the T based on the position of the cutting head after executing the cutting strategy, wherein the step of deleting comprises the following steps:

s301, setting a second cycle parameter j and a temporary set V'; then initializing a second cycle parameter j and a temporary set V', wherein j is equal to 1, and V is equal to V;

when the j is 1, selecting a sub-path graph corresponding to the initially selected corner point as a starting point of a jth sub-path graph for cutting, and taking the initially selected corner point as the jth sub-path graph for cutting;

when j is larger than 1, selecting a sub-path graph corresponding to the starting point as a jth sub-path graph for cutting;

s303, acquiring a corner point set v corresponding to the jth sub-path graph for cutting_jAcquiring the end point of the jth sub-path graph for cutting;

s304, making V ═V’-v_j(ii) a Screening out an angular point closest to the end point of the jth sub-path graph for cutting from the V' as a starting point of the jth +1 sub-path graph for cutting;

s305, repeating S302-304, making j ═ j +1, until all sub-path maps of the ith cutting pattern for cutting are selected;

s306, based on Q_iGenerating a cutting strategy of the ith cutting pattern for cutting according to the selection sequence of all sub-path diagrams of the cutting pattern, and updating the initial position of the cutting head based on the position of the cutting head after the cutting strategy is executed;

s307, deleting the corner point subset V corresponding to the ith cutting pattern from the T.

4. The cutting head control method of a plasma cutting machine according to claim 3, wherein the S306Q-based_iGenerating a cutting strategy of the ith cutting pattern for cutting according to the selection sequence of all sub-path diagrams of the cutting pattern, and updating the initial position of the cutting head based on the position of the cutting head after the cutting strategy is executed; the method comprises the following steps:

s3061, obtaining the selection sequence of all sub path diagrams of the cutting pattern, and sequencing from first to last to obtain a positive sequence sequencing list L1; and sorting from back to first to obtain a reverse sorting table L2;

s3062, circularly and alternately adding a positive sequence sorting table L1 and a negative sequence sorting table L2 to the cutting strategy set Gi until the number of elements in Gi is Q_i(ii) a Taking the cutting strategy set Gi as the cutting strategy of the ith cutting pattern for cutting;

s3063, determining Q_iThe parity of (c);

if Q_iIf the number of the cutting heads is odd, selecting the end point of the last sub-path graph in the positive sequence sorting table L1 as the initial position of the updated cutting head;

if Q_iEven, the starting point of the last sub-path map in the reverse sorting table L2 is selected as the updated initial position of the cutting head.

5. The method of claim 1, wherein when the sub-path diagram is a non-closed line, both ends of the non-closed line are used as corner points.

6. A cutting head control system of a plasma cutting machine is characterized by comprising a cutting task table extraction module, a sub-path function acquisition module, a sub-path graph corner acquisition module, an initial selection corner selection module, a cutting strategy generation module and a total cutting strategy acquisition module

The cutting task table extraction module is used for acquiring a cutting task table and an initial position of a cutting head;

the sub-path function acquisition module is used for acquiring sub-path functions corresponding to the sub-path graphs based on the sub-path graphs in the cutting task table;

the sub-path graph corner point acquisition module is used for acquiring a corner point set of the sub-path graph based on the sub-path graph; obtaining a corner set T ═ V corresponding to all cutting patterns₁，V₂，…}；

The initial selection corner selection module is used for screening out a corner closest to the initial position of the cutting head from the T to serve as an initial selection corner; acquiring a cutting pattern corresponding to the initially selected corner point, taking the cutting pattern as the ith cutting pattern to be cut, and determining the corresponding quantity Q in the cutting task table;

the cutting strategy generating module is used for determining the cutting sequence of all sub-path graphs in the ith cutting pattern to be cut and obtaining the cutting strategy of the cutting pattern based on the cutting sequence; updating the initial position of the cutting head and deleting the corner point subset V corresponding to the ith cutting pattern from the T based on the position of the cutting head after executing the cutting strategy; let i ═ i +1 for each cleavage strategy obtained.

The total cutting strategy obtaining module is used for obtaining the cutting strategies of all the cutting patterns and arranging the cutting strategies from small to large according to the value i to obtain the total cutting strategy.

7. The cutting head control system of a plasma cutting machine according to claim 6, wherein the cutting strategy generating module comprises an initializing unit, a sub-path diagram end point obtaining unit, a sub-path diagram selecting unit, and a cutting strategy calculating unit;

the initialization unit is used for setting a second cycle parameter j and a temporary set V'; then initializing a second cycle parameter j and a temporary set V', wherein j is equal to 1, and V is equal to V;

the sub-path graph selecting unit is used for selecting a sub-path graph corresponding to the initially selected angular point as a jth sub-path graph for cutting by taking the initially selected angular point as a starting point of the jth sub-path graph when j is equal to 1; when j is larger than 1, selecting a sub-path graph corresponding to the starting point as a jth sub-path graph for cutting;

the sub-path diagram end point obtaining unit is used for obtaining a corner point set v corresponding to the jth sub-path diagram for cutting firstly_jThen acquiring the end point of the jth sub-path graph for cutting;

the sub-path diagram starting point acquisition unit is used for enabling V '═ V' -V after the end point is acquired_j(ii) a Screening out an angular point closest to the end point of the jth sub-path graph for cutting from the V' as a starting point of the jth +1 sub-path graph for cutting, and after the starting point is obtained, making j equal to j + 1;

the cutting strategy calculation unit is used for calculating the cutting strategy based on Q_iGenerating a cutting strategy of the ith cutting pattern for cutting according to the selection sequence of all sub-path diagrams of the cutting pattern, and updating the initial position of the cutting head based on the position of the cutting head after the cutting strategy is executed; and deleting the corner point subset V corresponding to the ith cutting pattern from the T.

8. The cutting head control system of a plasma cutting machine according to claim 7, wherein the cutting strategy calculation unit is based on Q_iAnd the selection sequence of all sub-path diagrams of the cutting pattern generates the cutting strategy of the ith cutting pattern for cutting, and the specific steps of updating the initial position of the cutting head based on the position of the cutting head after the cutting strategy is executed are as follows:

s3061, obtaining the selection sequence of all sub path diagrams of the cutting pattern, and sequencing from first to last to obtain a positive sequence sequencing list L1; and sorting from back to first to obtain a reverse sorting table L2;

s3062, circularly and alternately adding a positive sequence sorting table L1 and a negative sequence sorting table L2 to the cutting strategy set Gi until the number of elements in Gi is Q_i(ii) a Taking the cutting strategy set Gi as the cutting strategy of the ith cutting pattern for cutting;

s3063, determining Q_iThe parity of (c);

if Q_iIf the number of the cutting heads is odd, selecting the end point of the last sub-path graph in the positive sequence sorting table L1 as the initial position of the updated cutting head;

if Q_iEven, the starting point of the last sub-path map in the reverse sorting table L2 is selected as the updated initial position of the cutting head.

9. The cutting head control system of a plasma cutting machine according to claim 6, wherein the sub-path diagram corner point obtaining module takes both ends of the non-closed line as corner points when the sub-path diagram is the non-closed line.

10. The cutting head control system of a plasma cutting machine according to claim 6, wherein the step of the sub path function acquiring module acquiring the sub path function includes:

generating a positioning coordinate system based on the cutting surface of the workpiece to be machined;

based on the positioning coordinate system, acquiring a sub-path function F ═ F corresponding to the sub-path graph₁(x)，f₂(x),…}。

Technical Field

The invention relates to the technical field of plasma cutting, in particular to a cutting head control method and system of a plasma cutting machine.

Background

When the cutting process is actually carried out, the cutting time is long, the important effect is achieved on improving the production efficiency and reducing the production cost, and the plasma cutting machine has the main advantages that when metal with small thickness is cut, the plasma cutting speed is high, and particularly when a common carbon steel sheet is cut, the speed can reach 5-6 times that of an oxygen cutting method.

When the existing plasma cutting machine is used for cutting, the cutting head starts to move from the initial position and starts to cut when moving to the position of the sub-path diagram, after the cutting of the workpiece to be machined with the same cutting pattern is completed, the cutting head is reset to the initial position and then starts to move from the initial position again and moves to the position of the sub-path diagram, and then the next cutting pattern is cut.

In the existing cutting head control method, when switching between different cutting patterns, the cutting head needs to be reset and then starts to cut, so that the displacement distance of the cutting head is increased, and the total cutting time is prolonged.

Disclosure of Invention

Technical problem to be solved

Aiming at the defects of the prior art, the invention provides a cutting head control method and a cutting head control system of a plasma cutting machine, which solve the problem that the cutting head needs to be reset to start cutting when switching between different cutting patterns.

(II) technical scheme

In order to achieve the purpose, the invention is realized by the following technical scheme:

a cutting head control method of a plasma cutting machine, the method comprising:

s1, acquiring an initial position of a cutting head and a cutting task table, wherein the cutting task table comprises a cutting pattern set, the number of each cutting pattern and a sub-path diagram set corresponding to each cutting pattern, setting a first cycle parameter i, and initializing the first cycle parameter to make i equal to 1;

acquiring a sub-path function corresponding to the sub-path diagram based on the sub-path diagram;

acquiring a corner set of the sub-path graph based on the sub-path graph; obtaining a corner set T ═ V corresponding to all cutting patterns₁，V₂，…}；

S2, screening the corner points closest to the initial position of the cutting head from the T to serve as initial selection corner points; obtaining the cutting pattern corresponding to the initially selected angular point as the ith cutting pattern for cutting, and determining the corresponding quantity Q in the cutting task table_i；

S3, determining the cutting sequence of all sub-path graphs in the ith cutting pattern to be cut, and obtaining the cutting strategy of the cutting pattern based on the cutting sequence; updating the initial position of the cutting head and deleting the corner point subset V corresponding to the ith cutting pattern from the T based on the position of the cutting head after executing the cutting strategy;

and S4, repeatedly executing S2-S3, and enabling i to be i +1 until the cutting strategies of all the cutting patterns are obtained, and arranging the cutting strategies according to the small value and the large value of i to obtain the total cutting strategy.

Further, the obtaining of the sub-path function corresponding to the sub-path graph based on the sub-path graph includes:

generating a positioning coordinate system based on the cutting surface of the workpiece to be machined;

based on the positioning coordinate system, acquiring a sub-path function F ═ F corresponding to the sub-path graph₁(x)，f₂(x),…}。

Further, in step S3, determining the cutting order of all sub-path diagrams in the ith cutting pattern to be cut, and obtaining the cutting strategy of the cutting pattern based on the cutting order; updating the initial position of the cutting head and deleting the corner subset V corresponding to the ith cutting pattern from the T based on the position of the cutting head after executing the cutting strategy, wherein the step of deleting comprises the following steps:

s301, setting a second cycle parameter j and a temporary set V'; then initializing a second cycle parameter j and a temporary set V', wherein j is equal to 1, and V is equal to V;

when the j is 1, selecting a sub-path graph corresponding to the initially selected corner point as a starting point of a jth sub-path graph for cutting, and taking the initially selected corner point as the jth sub-path graph for cutting;

when j is larger than 1, selecting a sub-path graph corresponding to the starting point as a jth sub-path graph for cutting;

s303, acquiring a corner point set v corresponding to the jth sub-path graph for cutting_jAcquiring the end point of the jth sub-path graph for cutting;

s304, let V ═ V' -V_j(ii) a Screening out an angular point closest to the end point of the jth sub-path graph for cutting from the V' as a starting point of the jth +1 sub-path graph for cutting;

s305, repeating S302-304, making j ═ j +1, until all sub-path maps of the ith cutting pattern for cutting are selected;

s306, based on Q_iGenerating a cutting strategy of the ith cutting pattern for cutting according to the selection sequence of all sub-path diagrams of the cutting pattern, and updating the initial position of the cutting head based on the position of the cutting head after the cutting strategy is executed;

s307, deleting the corner point subset V corresponding to the ith cutting pattern from the T.

Further, the S306 is based on Q_iGenerating a cutting strategy of the ith cutting pattern for cutting according to the selection sequence of all sub-path diagrams of the cutting pattern, and updating the initial position of the cutting head based on the position of the cutting head after the cutting strategy is executed; the method comprises the following steps:

s3061, obtaining the selection sequence of all sub path diagrams of the cutting pattern, and sequencing from first to last to obtain a positive sequence sequencing list L1; and sorting from back to first to obtain a reverse sorting table L2;

s3062, circularly and alternately adding a positive sequence sorting table L1 and a negative sequence sorting table L2 to the cutting strategy set Gi until the number of elements in Gi is Q_i(ii) a Taking the cutting strategy set Gi as the cutting strategy of the ith cutting pattern for cutting;

s3063, determining Q_iThe parity of (c);

if Q_iIf the number of the cutting heads is odd, selecting the end point of the last sub-path graph in the positive sequence sorting table L1 as the initial position of the updated cutting head;

if Q_iEven, the starting point of the last sub-path map in the reverse sorting table L2 is selected as the updated initial position of the cutting head.

Further, when the sub-path graph is a non-closed line, two ends of the non-closed line are used as corner points.

A cutting head control system of a plasma cutting machine comprises a cutting task table extraction module, a sub-path function acquisition module, a sub-path graph corner acquisition module, an initial selection corner selection module, a cutting strategy generation module and a total cutting strategy acquisition module

The cutting task table extraction module is used for acquiring a cutting task table and an initial position of a cutting head;

the sub-path function acquisition module is used for acquiring sub-path functions corresponding to the sub-path graphs based on the sub-path graphs in the cutting task table;

the sub-path graph corner point acquisition module is used for acquiring a corner point set of the sub-path graph based on the sub-path graph; obtaining a corner set T ═ V corresponding to all cutting patterns₁，V₂，…}；

The initial selection corner selection module is used for screening out a corner closest to the initial position of the cutting head from the T to serve as an initial selection corner; acquiring a cutting pattern corresponding to the initially selected corner point, taking the cutting pattern as the ith cutting pattern to be cut, and determining the corresponding quantity Q in the cutting task table;

the cutting strategy generating module is used for determining the cutting sequence of all sub-path graphs in the ith cutting pattern to be cut and obtaining the cutting strategy of the cutting pattern based on the cutting sequence; updating the initial position of the cutting head and deleting the corner point subset V corresponding to the ith cutting pattern from the T based on the position of the cutting head after executing the cutting strategy; let i ═ i +1 for each cleavage strategy obtained.

The total cutting strategy obtaining module is used for obtaining the cutting strategies of all the cutting patterns and arranging the cutting strategies from small to large according to the value i to obtain the total cutting strategy.

Further, the cutting strategy generation module comprises an initialization unit, a sub-path diagram end point acquisition unit, a sub-path diagram selection unit and a cutting strategy calculation unit;

the initialization unit is used for setting a second cycle parameter j and a temporary set V'; then initializing a second cycle parameter j and a temporary set V', wherein j is equal to 1, and V is equal to V;

the sub-path graph selecting unit is used for selecting a sub-path graph corresponding to the initially selected angular point as a jth sub-path graph for cutting by taking the initially selected angular point as a starting point of the jth sub-path graph when j is equal to 1; when j is larger than 1, selecting a sub-path graph corresponding to the starting point as a jth sub-path graph for cutting;

the sub-path diagram end point obtaining unit is used for obtaining a corner point set v corresponding to the jth sub-path diagram for cutting firstly_jThen acquiring the end point of the jth sub-path graph for cutting;

the sub-path diagram starting point acquisition unit is used for enabling V '═ V' -V after the end point is acquired_j(ii) a Screening out an angular point closest to the end point of the jth sub-path graph for cutting from the V' as a starting point of the jth +1 sub-path graph for cutting, and after the starting point is obtained, making j equal to j + 1;

the cutting strategy calculation unit is used for calculating the cutting strategy based on Q_iGenerating a cutting strategy of the ith cutting pattern for cutting according to the selection sequence of all sub-path diagrams of the cutting pattern, and updating the initial position of the cutting head based on the position of the cutting head after the cutting strategy is executed; and deleting the corner point subset V corresponding to the ith cutting pattern from the T.

Further, the cutting strategy calculation unit is based on Q_iAnd the selection sequence of all sub-path diagrams of the cutting pattern generates the cutting strategy of the ith cutting pattern for cutting, and the specific steps of updating the initial position of the cutting head based on the position of the cutting head after the cutting strategy is executed are as follows:

s3061, obtaining the selection sequence of all sub path diagrams of the cutting pattern, and sequencing from first to last to obtain a positive sequence sequencing list L1; and sorting from back to first to obtain a reverse sorting table L2;

s3062, positive sequence sorting table L1 and negative sequence sorting table L2Cyclically and alternately adding the elements to the cutting strategy set Gi until the number of the elements in the Gi is Q_i(ii) a Taking the cutting strategy set Gi as the cutting strategy of the ith cutting pattern for cutting;

s3063, determining Q_iThe parity of (c);

if Q_iIf the number of the cutting heads is odd, selecting the end point of the last sub-path graph in the positive sequence sorting table L1 as the initial position of the updated cutting head;

if Q_iEven, the starting point of the last sub-path map in the reverse sorting table L2 is selected as the updated initial position of the cutting head.

Further, when the sub-path graph is a non-closed line, the sub-path graph corner point obtaining module takes two ends of the non-closed line as corner points.

Further, the step of acquiring the sub-path function by the sub-path function acquiring module includes:

generating a positioning coordinate system based on the cutting surface of the workpiece to be machined;

based on the positioning coordinate system, acquiring a sub-path function F ═ F corresponding to the sub-path graph₁(x)，f₂(x),…}。

(III) advantageous effects

The invention provides a cutting head control method of a plasma cutting machine. Compared with the prior art, the method has the following beneficial effects:

determining a sub-path function and a corner point set of a sub-path graph based on a cutting task table; determining a first cutting pattern for cutting by selecting the corner point closest to the cutting head, determining the cutting sequence of all sub-path diagrams in the 1 st cutting pattern for cutting, and obtaining a cutting strategy of the cutting pattern based on the cutting sequence; and updating the initial position of the cutting head once based on the position of the cutting head after the cutting strategy is executed every time the cutting strategies of all the sub-path graphs in one cutting pattern are determined, taking the updated initial position of the cutting head as the position of the cutting head of the next cutting pattern, and repeatedly executing the operation to obtain the 2 nd cutting pattern and the corresponding cutting strategy. By analogy, the cutting strategies of all the cutting patterns in the cutting task table can be obtained, the value i is used for representing the cutting sequence of the cutting patterns, the plasma cutting machine can cut the cutting patterns from small to large according to the value i, and the sub-path diagram in each cutting pattern is cut according to the corresponding cutting strategy. Make the cutting head need not to reset and cut next cutting pattern again after the operation, shortened the displacement route of cutting head, and then shortened total cutting time.

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, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a flow chart of an embodiment of the present invention;

FIG. 2 is a diagram illustrating a cutting pattern in the cutting task list according to an embodiment of the present invention;

FIG. 3 is a diagram illustrating another exemplary cutting pattern in the cutting task list according to an embodiment of the present invention;

fig. 4 is a schematic diagram of a positioning coordinate system constructed in an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described, and it is obvious that the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. 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.

The embodiment of the application provides a cutting head control method and a cutting head control system of a plasma cutting machine, solves the problem that when different cutting patterns are switched, the cutting head needs to be reset and then starts cutting, and achieves the purpose of shortening the cutting time.

In order to solve the technical problems, the general idea of the embodiment of the application is as follows:

determining a sub-path function and a corner point set of a sub-path graph based on a cutting task table; determining a first cutting pattern for cutting by selecting the corner point closest to the cutting head, determining the cutting sequence of all sub-path diagrams in the 1 st cutting pattern for cutting, and obtaining a cutting strategy of the cutting pattern based on the cutting sequence; and updating the initial position of the cutting head once based on the position of the cutting head after the cutting strategy is executed every time the cutting strategies of all the sub-path graphs in one cutting pattern are determined, taking the updated initial position of the cutting head as the position of the cutting head of the next cutting pattern, and repeatedly executing the operation to obtain the 2 nd cutting pattern and the corresponding cutting strategy. By analogy, the cutting strategies of all the cutting patterns in the cutting task table can be obtained, the value i is used for representing the cutting sequence of the cutting patterns, the plasma cutting machine can cut the cutting patterns from small to large according to the value i, and the sub-path diagram in each cutting pattern is cut according to the corresponding cutting strategy. The cutting head is enabled to cut the next cutting pattern after reset operation is not needed, and the total cutting time is shortened.

In order to better understand the technical solution, the technical solution will be described in detail with reference to the drawings and the specific embodiments.