CN110286652B

CN110286652B - Control system method based on H-BOT structure

Info

Publication number: CN110286652B
Application number: CN201910533800.2A
Authority: CN
Inventors: 黄波; 黄定芳; 廖映华; 杨明; 周友恒; 杨栋程; 张如春; 鲜小波; 钟小雪
Original assignee: Sichuan University of Science and Engineering
Current assignee: Xi'an Mailang Automation Co ltd
Priority date: 2019-06-19
Filing date: 2019-06-19
Publication date: 2021-08-27
Anticipated expiration: 2039-06-19
Also published as: CN110286652A

Abstract

The invention provides a control system method based on an H-BOT structure, which includes a control module, an OLED module, an independent button, and a stepping motor, wherein the control module has serial asynchronous communication, data analysis, and G code analysis functional units; STEP and DIR pins control the forward and reverse rotation of the stepper motor by inputting different pulse signal frequencies and configuring different state values; the control module is connected to the OLED module and the independent button module signal through its serial asynchronous communication interface. Since the invention adopts the design of four-quadrant circular arc interpolation, the problem that the circular arc interpolation cannot cross quadrants is solved.

Description

Control system method based on H-BOT structure

Technical Field

The invention belongs to the field of numerical control open-loop control systems, and particularly relates to a control system method based on an H-BOT structure.

Background

The H-BOT structure converts a Cartesian coordinate system, a synchronous belt moves along with the rotation of two stepping motors, when the rotating directions of the left stepping motor and the right stepping motor are the same, an actuating mechanism moves towards an X axis, and when the two motors rotate in opposite directions, the actuating mechanism moves towards a Y axis. When both motors are rotating simultaneously, the torque of the stepper motor is greater than the torque generated by a single motor, improving motion response, and also reducing the weight of the stepper motor above the XY stage.

As shown in fig. 1, the movement principle of the stepping motor is as follows:

a moves along the reverse direction of B and moves towards the + Y axis;

a moves along the reverse direction and the forward direction and the negative Y axis;

a moves along the positive X axis;

a moves to the-X axis against B.

ΔX＝1/2(ΔA+ΔB)，ΔY＝1/2(ΔA-ΔB) (1-1)

ΔA＝ΔX+ΔY，ΔB＝ΔX-ΔY (1-2)

Ordinary circular interpolation is used in the H-BOT structure, because the conversion of coordinates cannot realize the normal work of the circular interpolation. When the circular arc is interpolated, the calculation formulas of the adjacent circular arc interpolation in two quadrants are different, and the feeding directions are different, so that the problem of over-quadrant needs to be considered when the circular arc is interpolated in over-quadrant, otherwise, an error occurs during interpolation.

The mark of the circular arc passing through the quadrant is a moving point coordinate x_i0 or y _i0. Therefore, when performing the arc interpolation, the destination point, i.e., the change of the interpolation calculation, is required for each coordinate axis advance. (see for details analysis of symbol discrimination when quadrant is interpolated by comparing circular arc traces point by point-Wudasu)).

In the documents of motion control algorithm of a planar H-BOT mechanism, Dingyunjun and Arduino-based sketch robot design, only algorithm research of linear interpolation in an H-BOT structure can be found, a corresponding circular interpolation algorithm is not found, and for a two-axis open source numerical control system GRBL (G code interpreter), circular interpolation adopts an arc to approach a circular arc, so that an interpolation algorithm of circular interpolation across quadrants is urgently needed.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides a control system method based on an H-BOT structure, which can adopt a four-quadrant circular interpolation design, reduces the judgment of quadrants, makes the calculation codes simpler and more efficient, and solves the problem that the circular interpolation of the original design cannot cross the quadrants.

The invention adopts the following technical scheme:

a control system method based on an H-BOT structure comprises the following steps:

step 1, initializing the system, pressing a key, inputting data from a serial port to a control module, and enabling the OLED to enter a main interface of the system.

Step 2, the control module analyzes the data, including extracting floating point numbers starting from specified characters in the character string, stopping when non-numeric characters are encountered, and assigning values to double-precision floating point numbers; the control module analyzes the G code.

Step 3, the control module judges motion control or steering engine control according to the input instruction;

if the motion control is adopted, calculating the pulse frequency;

if the interpolation is linear interpolation, the stepping motor is controlled to move to a designated position, and the control module, namely the lower computer returns data to the upper computer through a serial port.

If the interpolation is circular interpolation, the stepping motor is controlled to move to a designated position, and the control module, namely the lower computer returns data to the upper computer through a serial port.

The further technical scheme of the invention is that the control system of the H-BOT structure comprises: a control module, an OLED module, an independent key and a stepping motor,

the control module is provided with a serial port asynchronous communication, data analysis and G code analysis functional unit;

the STEP and DIR pins of the control module control the positive and negative rotation of the stepping motor by inputting different pulse signal frequencies and configuring different state values;

the control module is in signal connection with the OLED module and the independent key module through serial asynchronous communication interfaces of the control module.

The invention has the beneficial effects that:

the invention is suitable for control systems such as plotters, engraving machines, 3D printers and plotters. In particular to a set of control system which can normally realize interpolation motion in an XY plane coordinate system by adopting a mechanism with an H-BOT structure.

The control system ingeniously solves the embarrassing situation that the conventional H-BOT structure cannot directly adopt a circular interpolation algorithm, so that the algorithm is more optimized, the response time is prolonged, and the control system has a wide application prospect in the H-BOT structure control system.

Drawings

FIG. 1 background of the invention reference figure (schematic mechanical movement of H-BOT structure);

FIG. 2 is a control system flow diagram;

FIG. 3 is a linear interpolation plot in the first and second quadrants;

FIG. 4 is a pulse feed pattern for a linear interpolation;

FIG. 5 is a flowchart of a linear interpolation process;

FIG. 6 is an error analysis diagram of a linear interpolation;

FIG. 7 is a modified flow chart of linear interpolation;

FIG. 8 is a first quadrant down-the-arc pulse feed pattern;

FIG. 9 is a flow chart of a first quadrant forward and reverse circular arc interpolation pulse;

FIG. 10 is a flow chart of the first and second quadrant forward and reverse circular arc interpolation pulses;

FIG. 11 is a four-quadrant forward and reverse circular interpolation pulse feed pattern;

FIG. 12 is a flow chart of a general circular interpolation design;

FIG. 13 is a flow chart of modified circular interpolation;

FIG. 14 is a linear interpolation image of the first quadrant;

FIG. 15 is a linear interpolation image of the second quadrant;

FIG. 16 is a third quadrant linear interpolation image;

FIG. 17 is a fourth quadrant linear interpolation image;

FIG. 18 is a clockwise interpolation image spanning one and four quadrants;

FIG. 19 is a diagram of a counterclockwise interpolation image spanning one and two quadrants;

FIG. 20 is a clockwise interpolation image spanning two and three quadrants;

FIG. 21 is a circular interpolation image of a full circle;

fig. 22 is a circular interpolation image in the first quadrant.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention are described below clearly and completely, and it is obvious that the described embodiments are some, 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.

Notation and terminology interpretation:

H-BOT: the synchronous belt transmission mechanism is simplified after Corexy;

an OLED: organic Light-Emitting diodes (OLEDs);

g code: the G code is an instruction in the numerical control program. Commonly referred to as G instructions. The fast positioning, the inverse circle interpolation, the forward circle interpolation, the middle point circular arc interpolation, the radius programming and the skip processing can be realized by using the G code;

l Xe |: the total number of steps the cutter should travel in the X-axis direction;

i Ye i: the total number of steps the cutter should travel in the Y-axis direction;

f: a deviation value;

when the linear interpolation starts, F is equal to 0,

when the moving point passes through the coordinate axis, when Xc is 0 and Yc >0, the moving point passes through the positive half axis of the Y axis, and the rest is analogized in turn.

For convenience of description, some symbols are first defined as follows:

l: a straight line;

SR: following a circular arc;

NR: reverse circular arc;

number of subscript: quadrant of curve:

l1, L2, L3 and L4:

quadrant

1, 2, 3, and 4 straight lines;

SR1, SR2, SR3, and SR 4:

quadrants

1, 2, 3 and 4 follow the arc;

NR1, NR2, NR3 and NR 4:

quadrants

1, 2, 3 and 4 are the inverse arcs.

F_i+1＝F_i-2|Y_i|+1

F_i+1＝F_i+2|X_i|+1

F_i+1＝F_i-2|X_i|+1

F_i+1＝F_i+2|Y_i|+1。

F_iIs the interpolated deviation value, X_i，Y_iIs the coordinate of the moving point. Calculating deviation value to judge the next step F_i+1Direction of circular interpolation.

The system structure for implementing the invention needs to have the following functions:

the invention mainly realizes serial asynchronous communication, OLED display, independent key, serial data analysis, G code analysis, forward and reverse rotation of a stepping motor, linear interpolation and circular interpolation cross-quadrant.

(1) The serial port asynchronous communication is mainly used for completing real-time data transmission from the upper computer to the lower computer, the lower computer analyzes and executes movement by receiving the data of the upper computer, and specific parameters are returned after the movement is completed;

the USART serial communication is asynchronous communication configured through STM32, and data transmission between the upper computer and the lower computer is realized.

(2) The display module displays the current target position coordinate and the last state position coordinate, provides a human-computer interaction interface and can realize real-time monitoring on drawing;

the OLED display realizes a human-computer interaction interface on the singlechip through a 4-wire SPI communication interface.

(3) And independent keys are used for scanning whether the keys are pressed down or not, flag bits are set, if the conditions are met, the system is entered for drawing, and if not, the system exits from the drawing and waits for starting.

The independent key realizes the start-stop mode of the system through the selection of the key.

(4) And (3) data analysis, namely extracting floating point numbers starting from specified characters in the character string, stopping when non-numeric characters are encountered, and assigning values to double-precision floating point numbers.

The data analysis is to analyze the serial port data sent by the upper computer into corresponding specific numerical values.

(5) And G code analysis, wherein different state values are set according to the read G code, and the different state values are used for selecting the working modes of the following linear interpolation and circular interpolation.

(6) The normal operation of the stepping motor needs an annular distribution circuit and a pulse amplification circuit, but the driving module of the stepping motor adopted by the invention can automatically generate four paths of driving circuit signals only by inputting one pulse signal. Therefore, the purposes of forward and reverse rotation and speed regulation are achieved by configuring different state values of the DIR pin and the frequency of the pulse signals connected with the DIR of the A4988 module.

The stepping motor is controlled by setting the received G code into different state values, assigning coordinate values and selecting different motion modes.

(7) The invention adopts the optimization algorithm of the linear interpolation, and reduces the bytes occupied by the linear interpolation program in the singlechip.

(8) Circular interpolation, traditional circular interpolation can only accomplish circular interpolation in single quadrant, and this design adopts four-quadrant circular interpolation, has solved the problem that circular interpolation can not stride the quadrant.

A control system method based on an H-BOT structure is characterized by comprising the following steps:

if the linear interpolation is used in motion control, the pulse frequency is calculated, the stepping motor is controlled to move to a specified position, and the control module, namely the lower computer returns data to the upper computer through a serial port.

The linear interpolation algorithm is an interpolation method which adopts a small line segment to approach a large line segment. Any numerical control system has the capability of processing straight lines in different quadrants, firstly needs to determine four quadrants executed by interpolation, and then executes different interpolation schemes in different judged quadrants.

a. Optimization scheme of linear interpolation:

first, some symbols are defined as follows:

l: a straight line;

number of subscript: the quadrant where the curve is located;

l1, L2, L3 and L4: are

quadrant

1, 2, 3 and 4 straight lines, respectively;

linear interpolation of the second quadrant

As shown in fig. 3, when the straight line is in

quadrant

2, 3 or 4, the interpolation formula of the straight line in quadrant 1, which is symmetrical to the straight line, can be used for calculation, and only different feeding directions are used according to different quadrants.

That is, the interpolation problem of the 2 nd, 3 rd and 4 th quadrant straight lines can be reduced to the interpolation problem of the 1 st quadrant straight line symmetrical thereto.

The following table shows the interpolation feed direction and the interpolation calculation formula of four quadrant lines

Fig. 5 shows a flowchart of the linear interpolation process in the four quadrants, according to the table above and fig. 4.

The process of the point-by-point comparison linear interpolation mainly comprises four processes of deviation judgment, coordinate feeding, new deviation calculation and end point judgment. The flow shown in fig. 5 is to calculate the total steps Σ to be taken for X, Y coordinate axes. And feeding the X axis and the Y axis by judging the positive and negative of the deviation value F, wherein the negative value of the coordinate feeding is obtained by deviation calculation and table lookup, and finally when sigma is 0, the interpolation is finished.

As shown in fig. 6(a) and 6(b), fig. 6(a) and 6(b) illustrate that if the relative coordinates (Xe, Ye) are (0,4) and the first pass is uniformly determined in the X-axis feed direction, there is an error of root number 2 between (0,4) and (1,3) after the interpolation is completed, the Y-axis feed may be performed first after the determination of | Ye | > | Xe | is completed, and the same applies to (4, 0).

However, the above calculation concept has a disadvantage that if the cutting is performed in the X-axis direction uniformly when F is 0, the error ratio is large for the line of | Ye | > | Xe |, and the maximum error can be reached

Equivalent of one pulse. If we agree to feed uniformly in the Y-axis direction when F is 0, the error is also large for the line | Xe | > | Ye |, and the maximum can be reached similarly

Equivalent of one pulse.

In order to compensate for the above algorithm, assuming that the initial offset value F is 0, the error may be increased whether the first feed to the X axis or the Y axis is agreed.

In order to reduce the error, when F is 0, the process should be performed according to the specific situation of the straight line.

The method comprises the following steps that firstly, one step is appointed to be carried out in the Y-axis direction for a straight line of Ye | > | Xe |;

② for the straight line of | Xe | > | Ye |, one step is agreed to be taken in the X-axis direction.

The linear interpolation flow chart designed according to the improved algorithm is shown in fig. 7.

FIG. 7 is a process of determining the magnitude of | Ye | and | Xe | added to FIG. 5, wherein the total number of steps Σ taken by two coordinate axes is calculated X, Y, the magnitude of | Ye | and | Xe | is determined, and feeding of the X-axis and the Y-axis is performed by determining the positive and negative of the deviation value F, wherein the negative of the coordinate feeding is obtained by deviation calculation and table lookup;

in the case where F is 0, the following process should be performed according to the specific case of the straight line:

② for a straight line of | Xe | > | Ye |, it is agreed to go one step in the X-axis direction, and finally when Σ is 0, the interpolation is completed.

Simulation test

The simulation test environment is Matlab, linear interpolation of four quadrants is tested, F is 0, the initial state of the linear interpolation is obtained, and an initial feeding direction is given by comparing the X and Y feeding sizes of the absolute coordinates of the target.

As shown in fig. 14, in the first quadrant linear interpolation, the input end point abscissa X, Xe, the output end point coordinate Y, Ye, and h are 100, 30, and 4, respectively.

As shown in fig. 15, in the second quadrant linear interpolation, the input end point coordinate X, Xe, the input end point ordinate Y, Ye, and h are-30, 45, and 1, respectively.

As shown in fig. 16, in the third quadrant linear interpolation, the input end point abscissa X, Xe, the input end point ordinate Y, Ye, and the input step h are 90, 37, and 3, respectively.

As shown in fig. 17, in the fourth quadrant linear interpolation, the end point abscissa X is input, Xe is-39, the end point ordinate Y is input, Ye is-44, and the input step h is 1.

If the interpolation is circular interpolation, the stepping motor is controlled to move to a designated position, and the detection module returns data to the control module through the serial port.

Aiming at circular interpolation in four quadrants, firstly, analyzing the problem of circular arc trend of a first quadrant along a circular arc in the circular interpolation process except the quadrant problem.

A first quadrant is provided following the arc SE, as shown in fig. 8.

The deviation calculation formula is as follows:

the direction of movement of the tool is

Feeding one step to the-Y direction when the moving point is on the circular arc or in the area outside the circular arc;

and secondly, when the moving point is in the area inside the arc, feeding one step in the + X direction.

Discretizing the deviation value calculation formula to obtain the following calculation table:

summarizing the conditions of the forward arc and the reverse arc of the first quadrant as follows:

comparing these two cases, two features can be found:

(ii) when X, Y is reversed, the feeding direction of SR1 is changed to the feeding direction of NR 1; also the feed direction of NR1 is changed to the feed direction of SR 1.

X, Y is exchanged, the deviation calculation formula of SR1 is converted into a deviation calculation formula of NR 1; also the deviation calculation formula of NR1 is converted into a deviation calculation formula of SR 1.

The interpolation problem of the second, third and fourth quadrant forward circular arcs can be converted into the interpolation problem of the first quadrant reverse circular arc, and the conversion method comprises the following steps:

exchanging X, Y coordinates of the starting point of the circular arc to serve as the starting point of the inverse circular arc of the first quadrant;

the X, Y coordinates of the arc end point are exchanged to be used as the end point of the inverse arc of the first quadrant;

performing interpolation operation on the first quadrant inverse circular arc obtained by conversion:

when the calculation result is-X direction movement, an actual control signal in-Y direction is sent out;

when the calculation result is + Y direction movement, sending out an actual control signal in the + X direction;

symmetry of different quadrant circular interpolation

By analyzing arcs of different directions in other quadrants in a similar manner, the feed direction and deviation calculation formula is shown in fig. 11 and the following table:

(1) SR1 → NR2 (X-axis reversal);

SR1 → NR4 (Y-axis reversal);

SR1 → SR3(X and Y axes are reversed at the same time);

NR1 → SR2 (X-axis reversal);

NR1 → SR4 (Y-axis reversal);

NR1 → NR3 (X-axis, Y-axis are reversed at the same time);

(2) SR1 → NR1(X, Y for exchange);

NR1 → SR1(X, Y exchange);

its features can be summarized as follows:

(1) SR1 → NR2 (X-axis reversal);

SR1 → NR4 (Y-axis reversal);

SR1 → SR3(X and Y axes are reversed at the same time);

the deviation calculation formulas of the four line types of SR1, NR2, SR3 and NR4 are the same.

NR1 → SR2 (X-axis reversal);

SR1 → SR4 (Y-axis reversal);

SR1 → NR3 (X-axis, Y-axis are reversed at the same time);

the formulas for calculating the deviations of the four line types NR1, SR2, NR3 and SR4 are also the same.

(2) SR1 → NR1(X, Y for exchange);

NR1 → SR1(X, Y exchange);

it can be seen that by switching the X, Y signal and changing the feeding direction, the arc interpolation motion of different directions of each quadrant can be completed by performing the interpolation calculation of the arc following the first quadrant or the interpolation calculation of the arc reversing the first quadrant. The flow chart corresponding to the above table is shown in fig. 12.

Explanation of four-quadrant circular interpolation

Aiming at the phenomenon that the circular arc crosses a quadrant and enters and exits from the original four-quadrant interpolation, after the coordinate of an H-Bot structure is converted, the recorded position often has the characteristic of trans-quadrant, and the four-quadrant circular interpolation cannot meet the requirement.

The straight line can only be in one quadrant, so there is no over-quadrant problem. However, the arc may span several quadrants, and corresponding processing is required at the junction of two quadrants, which is the problem of the arc crossing the quadrants.

When the circular arc passes through the quadrant, the device has the following characteristics:

firstly, before and after passing through a quadrant, the sign of a moving point coordinate is changed;

and ② after passing through the quadrant, the trend of the arc is unchanged.

The sequence of the inverse circular arc passing through the quadrant is as follows: NR1 → NR2 → NR3 → NR4 → NR1 → ·

The sequence of passing through the quadrants along the circular arc is as follows: SR1 → SR4 → SR3 → SR2 → SR1 → · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · → SR's → SR4 → SR 3526 → SR2 → SR

And thirdly, the quadrant-passing circular arc and the coordinate axis have intersection points, and when the moving point is on the coordinate axis, a coordinate value is zero. This point may be used as a sign of over-quadrant.

And fourthly, judging the end point, wherein the three methods cannot be directly used simply, and otherwise, a part of circular arc outline is lost.

The three methods are respectively as follows:

1. determining the distance of the moving point from the centre of the circle, i.e.

2. In the ordinary circular interpolation of the judgment quadrant,

F_i+1＝F_i-2Y_i+1

F_i+1＝F_i+2X_i+1

3. by using the novel circular interpolation of symmetry,

F_i+1＝F_i-2|Y_i|+1

F_i+1＝F_i+2|X_i|+1

F_i+1＝F_i-2|X_i|+1

F_i+1＝F_i+2|Y_i|+1

according to the idea of circular interpolation mentioned in the theory of linear and circular interpolation across arbitrary quadrants research and trajectory simulation-Wangweig, only the number of intersection points between the circular arc at the starting point of the circular interpolation and the circular arc at the end point needs to be judged for several times. The invention does not need to carry out the judgment, judges the quadrant where the moving point is positioned again after each interpolation is finished, and can skillfully avoid calculating the number of intersection points of the circular arc and the coordinate axis.

The process of the circular interpolation across quadrants can be completed only by continuously judging the quadrant of the moving point in the process of the circular interpolation and then carrying out the ordinary circular interpolation program. One of the difficulties is how to judge the coordinate system where the next movement trend of the moving point is when the moving point moves on the coordinate axis, and the following conclusions can be drawn because the movement trends of the forward and backward arcs are different. If it is on the coordinate axis, then,

clockwise arc:

if (Xc ═ 0& & Yc >0) motion trend is the first quadrant

if (Xc >0& & Yc ═ 0) motion trend is fourth quadrant

if (Xc ═ 0& & Yc <0) motion trend is the third quadrant

if (Xc <0& & Yc ═ 0) motion trend is the second quadrant

Counterclockwise arc:

if (Xc ═ 0& & Yc >0) motion trend is the second quadrant

if (Xc <0& & Yc ═ 0) motion trend is the third quadrant

if (Xc ═ 0& & Yc <0) motion trend is the fourth quadrant

if (Xc >0& & Yc ═ 0) motion trend is the first quadrant

The method avoids sacrificing the calculation time of the floating point number of the singlechip. Compared with the interpolation algorithm mentioned in the literature of 'any quadrant crossing linear and circular interpolation principle research and track simulation' adopted before, the method is simpler and faster.

The invention receives and analyzes a sentence of G code to execute, and executes an interpolation process after the sentence of G code is analyzed. The stm32 single chip microcomputer is a 32-bit microcontroller with ARM core-M3 as a carrier, is an MCU with the highest operation speed except a DSP in the same price, and can meet the normal working requirement.

Simulation environment Matlab, circular interpolation data content:

as shown in fig. 18, the input end point abscissa Xc, Xc is 70, the input end point ordinate Yc, Yc is 71, the input end point abscissa X, Xt is 56, the input end point ordinate Y, Yt is-82, the input bsiscw 0- > clockwise, 1- > counterclockwise, bsisccw is 0, and the step length is 227.

As shown in fig. 19, across the first and second quadrants, the input end abscissa Xc, Xc is 70, the input end ordinate Yc, Yc is 71, the input end abscissa X, Xt is-94, the input end ordinate Y, Yt is 34, the input bsicw 0- > clockwise 1- > counterclockwise, bsicw 1, and the step length is 259.

As shown in fig. 20, in the interpolation of the optimal arc, the end point abscissa Xc, Xc-59, the end point ordinate Yc, Yc-81, the end point abscissa X, Xt-94, the end point ordinate Y, Yt-34, the input bsiscw 0- > clockwise 1- > counterclockwise, bsiscw 1, and the step 644.

As shown in fig. 21, in the round interpolation, the input end point abscissa Xc, Xc equals 100, the input end point ordinate Yc, Yc equals 0, the input end point abscissa X, Xt equals 100, the input end point ordinate Y, Yt equals 0, the input bsiscw 0- > clockwise 1- > counterclockwise, bsiscw equals 0, and the step size equals 800.

As shown in fig. 22, 1/4 is interpolated by circular interpolation, where the input end point abscissa Xc, Xc is 100, the input end point ordinate Yc, Yc is 0, the input end point abscissa X, Xt is 0, the input end point ordinate Y, Yt is 100, the input bsicw 0- > clockwise 1- > counterclockwise, bsicw 1, and the step size is 200.

The further technical scheme of the invention is that the control system of the H-BOT structure comprises: the control module, the OLED module, the independent keys and the stepping motor;

the DIR pin of the control module controls the positive and negative rotation of the stepping motor by inputting different pulse signal frequencies and configuring different state values;

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. a control system method based on H-BOT structure, is characterized in that, comprises the following steps:

Step 1. System initialization settings, press the button, input data from the serial port to the control module, and make the OLED enter the main interface of the system;

Step 2. The control module parses the data, including extracting the floating-point number starting with the specified character in the string, stopping when it encounters a non-numeric character, and assigning it to the double-precision floating-point value; the control module parses the G code;

Step 3. The control module judges motion control or steering gear control according to the input command;

If it is motion control, the control module calculates the pulse frequency;

a. In the case of linear interpolation, the stepper motor is controlled to move to the specified position, and the control module, that is, the lower computer, returns the data to the upper computer through the serial port;

The linear interpolation is specifically:

The control module determines the coordinates of the starting point and the ending point, and then calculates the total number of steps to be taken on the X and Y coordinate axes ∑ and judges the sizes of |Ye| and |Xe| The feed of the Y-axis, in which the direction of the coordinate feed is obtained through deviation calculation and table look-up;

For the case of F=0, according to the specific situation of the straight line, it is processed separately:

①For the line of |Ye|>|Xe|, it is agreed to take one step in the Y-axis direction;

②For the straight line of |Xe|>|Ye|, it is agreed to take one step in the X-axis direction, and when ∑=0, the interpolation is completed;

b. If it is circular interpolation, control the stepper motor to move to the specified position, and the control module, that is, the lower computer, returns the data to the upper computer through the serial port;

Aiming at the circular interpolation in the four quadrants, firstly analyzes that in the circular interpolation process of the first quadrant, in addition to the quadrant problem, there is also the circular arc direction problem;

With the first quadrant arc SE:

The formula for calculating the deviation is:

The tool moving direction is:

① When the moving point is on the arc or in the outer area of the arc, feed one step in the -Y direction;

② When the moving point is in the inner area of the arc, feed one step in the +X direction;

③ Discretize the calculation formula of deviation value:

Comparing these two cases, two characteristics are found:

Swap X and Y, then the feed direction of SR1 is changed to the feed direction of NR1; the same feed direction of NR1 is changed to the feed direction of SR1;

Swap X and Y, then the deviation calculation formula of SR1 will be transformed into the deviation calculation formula of NR1; the same deviation calculation formula of NR1 will be transformed into the deviation calculation formula of SR1;

The interpolation problem of the second, third and fourth quadrant arcs is converted into the interpolation problem of the first quadrant inverse arc, and the conversion method is as follows:

③ Swap the X and Y coordinates of the starting point of the arc as the starting point of the inverse arc in the first quadrant;

Then swap the X and Y coordinates of the arc end point as the end point of the inverse arc in the first quadrant;

④ Interpolate the inverse arc of the first quadrant obtained by conversion:

When the calculation result is movement in the -X direction, the actual control signal in the -Y direction is sent out;

When the calculation result is movement in the +Y direction, the actual control signal in the +X direction is sent out;

Using the symmetry method of circular arc interpolation in different quadrants to analyze arcs with different directions in other quadrants, the feed direction and deviation calculation formulas are as follows:

(1) SR1→NR2, the X axis is reversed;

SR1→NR4, Y-axis is reversed;

SR1→SR3, X axis and Y axis are reversed at the same time;

NR1→SR2, the X axis is reversed;

NR1→SR4, Y-axis is reversed;

NR1→NR3, X axis and Y axis are reversed at the same time;

(2) SR1→NR1, X and Y are swapped;

NR1→SR1, X, Y swap;

Its characteristics are summarized as follows:

(1) SR1→NR2, the X axis is reversed;

SR1→NR4, Y-axis is reversed;

SR1→SR3, X axis and Y axis are reversed at the same time;

The deviation calculation formulas of the four line types SR1, NR2, SR3 and NR4 are the same;

NR1→SR2, the X axis is reversed;

SR1→SR4, Y-axis is reversed;

SR1→NR3, the X axis and the Y axis are reversed at the same time;

The deviation calculation formulas of the four line types NR1, SR2, NR3 and SR4 are also the same;

(2) SR1→NR1, X and Y are swapped;

NR1→SR1, X, Y swap;

By reversing the X and Y signals and changing the feed direction, the circular interpolation movements of each quadrant with different directions are completed by performing the interpolation calculation of the first quadrant forward circular arc or the first quadrant reverse circular arc; The arc crosses the quadrants, which is different from the original four-quadrant interpolation. After the coordinate conversion of the H-Bot structure, the recorded position often has the characteristics of crossing the quadrants, and the four-quadrant arc interpolation cannot meet the requirements;

When the arc passes through the quadrant, it has the following characteristics:

⑤ Before and after the quadrant, the symbol of the moving point coordinates will change;

⑥After passing through the quadrant, the direction of the arc remains unchanged;

The sequence of inverse arc passing through the quadrants is: NR1→NR2→NR3→NR4→NR1→...

The sequence of passing the quadrant along the arc is: SR1→SR4→SR3→SR2→SR1→...

⑦ There must be an intersection between the quadrant arc and the coordinate axis. When the moving point is on the coordinate axis, there must be a coordinate value of zero, and this point is used as the sign of the quadrant;

⑧ The following three methods cannot be simply used for end point discrimination, otherwise part of the arc outline will be lost;

The three methods are:

a. Determine the distance between the moving point and the center of the circle, namely

b. Ordinary judging quadrant circular interpolation,

F _i+1 = F _i -2Y _i +1

F _i+1 = F _i +2X _i +1

c. New circular interpolation using symmetry,

F _i+1 =F _i -2|Y _i |+1

F _i+1 = F _i +2|X _i |+1

F _i+1 =F _i -2|X _i |+1

F _i+1 = F _i +2|Y _i |+1

Judge the moving direction of the tool until the coordinates of the moving point are the same as the target end point;

If passing through the coordinate axis, then

For a clockwise arc:

If (Xc==0&&Yc>0) the movement trend is the first quadrant,

If (Xc>0&&Yc==0) the movement trend is the fourth quadrant,

If (Xc==0&&Yc<0) the movement trend is the third quadrant,

If (Xc<0&&Yc==0) the movement trend is the second quadrant,

until ∑ = 0 terminates;

or a counterclockwise arc:

If (Xc==0&&Yc>0) the movement trend is the second quadrant,

If (Xc<0&&Yc==0) the movement trend is the third quadrant,

If (Xc==0&&Yc<0) the movement trend is the fourth quadrant,

If (Xc>0&&Yc==0) the movement trend is the first quadrant,

until Σ=0 terminates.