CN107192361A - The kinetic control system and its control method of a kind of three coordinate measuring machine - Google Patents

Abstract

The invention provides a motion control system of a three-coordinate measuring machine, including a PC, a motion controller, a pulse converter, an X-axis servo driver, a Y-axis servo driver, a Z-axis servo driver, an X-axis servo motor, and a Y-axis servo Motor, Z-axis servo motor, coordinate measuring machine, sensor, low-speed photocoupler and high-speed photocoupler, motion controller and PC, pulse converter, low-speed photocoupler and high-speed photocoupler connected, pulse converter and X-axis servo driver, Y-axis servo driver and Z-axis servo driver are connected, the three-axis servo driver is connected to the three-axis coordinate measuring machine through the three-axis servo motor, and the sensor is connected to the X-axis servo motor, Y-axis servo motor, Z-axis servo motor, low speed Optocoupler and high-speed optocoupler connection. The invention also provides a motion control method of a three-coordinate measuring machine, which can control the movement and positioning of each axis of the three-coordinate measuring machine accurately.

Description

A motion control system and control method for a three-coordinate measuring machine

technical field

The invention relates to a three-coordinate measuring machine, in particular to a motion control system and a control method of the three-coordinate measuring machine.

Background technique

The motion controller is a control device that coordinates and controls the motor-driven target device or equipment (such as a three-coordinate measuring machine) to make it move according to the expected operating trajectory. It is the core technical equipment of electronics and machinery manufacturing industry. According to the data communication method with the main control computer, the current motion controllers are mainly divided into two categories: one is based on the computer standard parallel bus (such as PCI, ISA bus) motion controller, and the other is based on the computer standard serial bus ( Such as USB, RS-232, Ethernet, etc.) motion controller. The former is usually made into a motion control card, which communicates with the main control computer through the "golden finger" (that is, the golden-yellow conductive contact piece of the memory stick, computer hardware, such as: between the memory stick and the memory slot, the graphics card and the graphics card slot, etc.) It is physically connected to the expansion slot of the motherboard, and shares the power supply with the main control computer. The latter is usually made as an independent controller, which is connected to the main control computer through a "serial communication cable". Because it is completely separated from the main control computer in structure, it is also called an independent motion controller. Practice shows that the motion controller based on the parallel bus has the following disadvantages: (1) The motion control card cannot be separated from the main board of the main control computer, and is susceptible to electromagnetic radiation interference; (2) The motion control card and the main control computer share a power supply, which is easy to generate Coupling, especially affects the control accuracy of the analog control (DAC) output; (3) The motion control card is mechanically connected to the parallel bus of the main control computer through the "golden finger", which is prone to poor contact and makes the control system unstable; (4 ) between the motion control card (or main control computer) and the servo drive requires a relatively long cable connection, which is easily affected by the environment, and there are missing pulses and inaccurate positioning of each axis. The above-mentioned deficiencies have aroused widespread concern of the world's major motion controller manufacturers.

The motion controller that controls the three-coordinate measuring machine is usually a motion control card that uses a parallel bus, and uses an open-loop method for motion control. This method is only a one-way transmission from the PC to the motion control card, and cannot convert the three-coordinate measurement The information of the machine is fed back to the motion control card, and then to the main control computer, so that the main control computer cannot adjust the position of the three-coordinate measuring machine by controlling the motion control card, and it is easy to lose pulses and the movement positioning of each axis of the three-coordinate measuring machine. inaccurate phenomenon.

As for the motion controller based on the computer standard serial bus, the USB bus has many advantages beyond the ISA and PCI bus because of its plug-and-play, hot-swappable, cost-effective, and expandable up to 127 controlled devices. to develop rapidly.

Since the 1990s, the CNC system has entered the stage of the sixth generation of PC-based CNC technology, especially the open CNC technology of "PC + motion controller" has become the main direction today. The open motion controller based on computer standard bus is still the mainstream of market development. Therefore, it is necessary to develop an open motion controller based on computer standard bus.

Chinese invention patent application CN106444535A discloses a motion controller and a control method, specifically, it relates to a motion controller and a control method, including a motion controller body, 1-8 extension modules and extension cables, the extension The connection includes data read-write connection, data transfer connection and enable connection. On the one hand, the data read-write connection is connected to the motion controller body, and on the other hand, it is respectively connected to each expansion module; - Data 7 transmission connection, the data transmission connection is a bidirectional signal line, which is connected to the motion controller body on the one hand, and connected to each expansion module on the other hand; the enabling connection is used to connect the motion controller body and each expansion module in series . The invention adopts a motion controller based on a computer standard parallel bus. Due to the limited resources of the motion controller itself, the matching between the external module and the motion controller is poor, the price is expensive, and the system is complex and unstable. At the same time, in many applications, some additional modules are needed to complete the application of the system.

Chinese utility model patent application CN201955650U discloses a three-coordinate motion controller, which relates to the application field of single-chip microcomputer and electronic technology, especially a three-coordinate motion controller with simple positioning control. Including control box, circuit board, man-machine operation interface, manual pulse generator MPG and control circuit, the man-machine operation interface has LED display and control buttons, the man-machine operation interface and manual pulse generator MPG are set on the control box , the circuit board is installed in the control box, and the control circuit is assembled on the circuit board. The control circuit includes a single-chip microcomputer, an input signal circuit part, an output signal circuit part, a manual pulse generator MPG control circuit part, an LED display and a key circuit part and a string The line communication interface circuit part, each part is an independent function module, and the single-chip microcomputer circuit is connected with other parts of the function circuit module through the system bus. This utility model adopts a motion controller based on computer standard parallel bus, which can only realize a small number of motion control functions, lacks circular interpolation positioning in self-motion functions, and cannot meet the accurate requirements of motion trajectory control.

Chinese invention patent application CN106502143A discloses a computer-based motion control card construction platform system, including a computer, a motion control card electrically connected to the computer through an ISA bus, and an execution unit electrically connected to the motion control card; the motion control The card includes a bus interface circuit, a communication interface circuit electrically connected to the bus interface circuit, a DSP electrically connected to the communication interface circuit, and an encoder signal processing circuit and a pulse generator electrically connected to the DSP; the execution unit includes multiple A driver, and a motor electrically connected to the driver. The invention has the advantages of simple structure, reliable operation and low cost, and can meet the requirements of high-performance control systems such as multi-axis linkage numerical control machine tools and robots. However, due to the use of motion control cards based on computer standard parallel buses (such as PCI, ISA bus), the motion control card cannot be separated from the main control computer motherboard, and is susceptible to electromagnetic radiation interference; the motion control card and the main control computer share power, which is easy to generate power Coupling, in particular, affects the control accuracy of the analog control (DAC) output.

Contents of the invention

One of the technical problems to be solved by the present invention is to provide a motion control system for a three-coordinate measuring machine, which uses a closed-loop motion control system based on USB communication to control the three-coordinate measuring machine, which not only has plug-and-play, It supports hot-swapping, high cost performance, and has many advantages beyond the reach of ISA and PCI buses, such as being able to expand up to 127 controlled devices. Inaccurate phenomenon; the closed-loop numerical control system adopting "PC + motion controller" not only has the characteristics of strong information processing ability, high degree of openness, accurate motion trajectory control, and good versatility, but also greatly improves the Existing processing and manufacturing precision, flexibility and ability to meet market demand.

One of problem of the present invention is realized like this:

A motion control system of a three-coordinate measuring machine, the motion control system comprising a PC, a motion controller, a pulse converter, an X-axis servo driver, a Y-axis servo driver, a Z-axis servo driver, an X-axis servo motor, a Y-axis Servo motor, Z-axis servo motor, coordinate measuring machine, sensor, low-speed photocoupler and high-speed photocoupler, the motion controller is connected with PC, pulse converter, low-speed photocoupler and high-speed photocoupler respectively, The pulse converter is respectively connected with the X-axis servo driver, the Y-axis servo driver and the Z-axis servo driver, the X-axis servo driver is connected to the coordinate measuring machine through the X-axis servo motor, and the Y-axis servo driver is connected to the three-coordinate measuring machine through the Y-axis servo driver. The servo motor is connected to the three-coordinate measuring machine, the Z-axis servo driver is connected to the three-coordinate measuring machine through the Z-axis servo motor, and the sensors are respectively connected to the X-axis servo motor, the Y-axis servo motor, the Z-axis servo motor, and the low-speed photoelectric coupling device and high-speed optocoupler connection.

Further, the motion control system further includes a driving status output circuit and a status indicator light, and the status indicator light is connected to the motion controller through the driving status output circuit.

Further, the model of the motion controller is APAX-5580.

Further, the model of the pulse converter is SA1400.

Further, the sensor is a grating ruler or an encoder.

The second technical problem to be solved by the present invention is to provide a motion control method for a three-coordinate measuring machine, which adopts a closed-loop motion control system based on USB communication to control the three-coordinate measuring machine, which not only has plug-and-play, It supports hot-swapping, high cost performance, and has many advantages beyond the reach of ISA and PCI buses, such as being able to expand up to 127 controlled devices. Inaccurate phenomenon; the closed-loop numerical control system adopting "PC + motion controller" not only has the characteristics of strong information processing ability, high degree of openness, accurate motion trajectory control, and good versatility, but also greatly improves the Existing processing and manufacturing precision, flexibility and ability to meet market demand.

Two of problem of the present invention is realized like this:

A motion control method for a three-coordinate measuring machine, the motion control method needs to provide a motion control system for a three-coordinate measuring machine as claimed in claim 1, and the motion control method specifically includes the following steps:

Step 1, the PC is connected to the motion controller through a serial bus to communicate, and the PC sends a control command to the motion controller;

Step 2. After receiving the control instruction, the motion controller generates a corresponding drive pulse signal and direction pulse signal and sends them to the pulse converter;

Step 3. After receiving the driving pulse signal and the direction pulse signal, the pulse converter converts it into a driving digital signal and sends it to the corresponding X-axis servo driver, Y-axis servo driver, and Z-axis servo driver;

Step 4. After the X-axis servo driver, Y-axis servo driver, and Z-axis servo driver receive the driving digital signal, they respectively drive the X-axis servo motor, Y-axis servo motor, and Z-axis servo motor to rotate to complete corresponding mechanical actions. Thereby driving the movement of the three axes of the three-coordinate measuring machine;

Step 5, the sensor collects general output signals and external feedback signals of the X-axis servo motor, Y-axis servo motor, and Z-axis servo motor, and sends them to the low-speed photocoupler and the high-speed photocoupler;

Step 6. The low-speed photocoupler receives the general output signal and sends it to the motion controller after filtering; the high-speed photocoupler receives the external feedback signal and sends it to the motion controller after electrical isolation

Step 7. The motion controller feeds back the real-time status of the CMM to the PC through the general output signal and the external feedback signal, so that the PC can perform scheduling.

Further, the motion controller has two modes for outputting pulses: a fixed-length pulse output mode and a continuous pulse output mode, and the corresponding pulse output mode is selected by setting a register in the motion controller.

Further, the communication mode between the PC and the motion controller is USB communication through the USB bus.

Further, the general output signal includes limit switch signal, in-position signal, service alarm signal and emergency switch signal, and the external feedback signal includes fault signal, motor operation parameter signal and ambient temperature signal.

The advantages of the present invention are:

(1) Generate the drive pulse signal and direction pulse signal through the motion controller, drive the servo motor to complete the corresponding mechanical operation, and feed back the real-time state of the three-coordinate measuring machine to the PC through the motion controller, which is convenient for the PC to schedule, and Complete the action command issued by the PC;

(2) The photoelectric coupler (low-speed photocoupler and high-speed photocoupler) is used for electrical isolation between the motion controller and the sensor to improve the anti-interference ability. The low-speed photocoupler is used to receive general output signals, which can filter and The delay function makes the controller work stably. At the same time, the high-speed optocoupler is used to receive the external feedback signal of the feedback and perform electrical isolation;

(3) The drive pulse signal and direction pulse signal generated by the motion controller are generated by the servo driver to generate a drive digital signal to control the drive of the servo motor, and the external feedback signal is input to the motion controller after passing through the high-speed photocoupler, and the general output signal is passed through After the low-speed optocoupler is input to the general input port of the motion controller. This not only effectively eliminates external electromagnetic interference (EMI), improves the quality of two-way transmission signals, but also improves the long-distance anti-interference ability of signals;

(4) USB realizes the communication between the PC and the motion controller. The real-time state of the three-coordinate measuring machine is fed back to the PC through the motion controller, so as to facilitate the control of the PC. At the same time, the control signal of the PC is transmitted to the motion controller through the USB bus. The single-chip microcomputer is also used for USB communication between the PC and the motion controller. The powerful functional modules inside the single-chip microcomputer greatly simplify the development of USB technology, and the use of full-speed USB transmission ensures a high data transmission rate. At the same time, there is no need to add a separate USB power supply, and devices such as A/D converter, timer, and USB controller work independently of each other, which has obvious advantages for improving the integration of the controller.

Description of drawings

The present invention will be further described below in conjunction with the embodiments with reference to the accompanying drawings.

FIG. 1 is a schematic structural diagram of a motion control system of a three-coordinate measuring machine according to the present invention.

FIG. 2 is a flow chart of the execution of a motion control method of a three-coordinate measuring machine according to the present invention.

detailed description

Please refer to Fig. 1, a motion control system of a three-coordinate measuring machine according to the present invention, the motion control system includes a PC, a motion controller, a pulse converter, an X-axis servo driver, a Y-axis servo driver, a Z-axis Servo drive, X-axis servo motor, Y-axis servo motor, Z-axis servo motor, three-coordinate measuring machine, sensor, low-speed photocoupler and high-speed photocoupler, the sensor is a grating ruler or an encoder;

The motion controller is respectively connected with PC, pulse converter, low-speed photocoupler and high-speed photocoupler, and the pulse converter is connected with X-axis servo driver, Y-axis servo driver and Z-axis servo driver respectively. The X-axis servo driver is connected to the three-coordinate measuring machine through the X-axis servo motor, the Y-axis servo driver is connected to the three-coordinate measuring machine through the Y-axis servo motor, and the Z-axis servo driver is connected to the three-coordinate measuring machine through the Z-axis servo motor machine, the sensors are respectively connected with the X-axis servo motor, Y-axis servo motor, Z-axis servo motor, low-speed photocoupler and high-speed photocoupler; the whole system constitutes a closed-loop control system.

The motion control system also includes a drive status output circuit and a status indicator light, and the status indicator lamp is connected to the motion controller through the drive status output circuit; by using a single-chip microcomputer to carry out USB communication between the PC and the motion controller, it can be greatly improved. It simplifies the development of USB technology, uses USB full-speed transmission to ensure a high data transmission rate, and does not need to add a separate USB power supply, and A/D converters, timers, USB controllers and other devices work independently of each other. Controller integration has obvious advantages. At the same time, the motion controller is connected to the drive state output circuit, and the single-chip microcomputer is connected to the state indicator light, which can realize the state display of the feedback signal and add an external control button.

The motion controller used is Advantech's programmable automation controller model APAX-5580, which is equipped with two Gigabit LAN controllers. The controller chips in this model all use fully compatible Intel 1x i218 and 1x i210 Ethernet, the controller has IEEE 802.3u 10/100Base-T CSMA/CD standard and IEEE 802.3ab specification for 1000Mbps Ethernet. The Ethernet port provides a standard RJ-45 jack plate and LED indicators to show its link (green LED) and activity (yellow LED) status. The controller can control 5 axes at the same time to realize multi-axis coordinated motion. At the same time, Advantech APAX-5580 controller is equipped with dedicated Codesys PLC Control software for motion control development. Codesys PLC Control provides an easy way for PLC programming, which can freely handle the powerful IEC language. The use of editors and debugging functions is based on advanced programming languages and proven program development environments. In the present invention, the Advantech APAX-5580 controller controls three servo motors to complete the X-axis movement, Y-axis movement and Z-axis movement of the three-coordinate measuring machine respectively. The X-axis, Y-axis, and Z-axis each have 4 switch input signals, namely left (up), right (down), limit position (MLTP, LMTM), origin (Home) position and working position (INO, INI).

The model of the pulse converter is SA1400.

The motion controller and the sensor are electrically isolated by a photoelectric coupler to improve the anti-interference ability and make the motion controller work stably. The motion controller is respectively connected to a low-speed photocoupler and a high-speed photocoupler to realize the collection of output signals. The low-speed photocoupler uses the PC357 chip of Shpar Company to receive general output signals, including limit switch signals (LMT+/LMT1) , in-position signal (INPOS), service alarm signal (ALARM) and emergency switch signal (EMGN), which can play the role of filtering and delay; high-speed photocoupler, using AGL company HCPL-2630 chip, used to receive feedback coding The signal of the device and the grating ruler are electrically isolated, and its maximum passing frequency can reach 10MHz.

Please refer to Fig. 2, a motion control method of a three-coordinate measuring machine of the present invention, the motion control method needs to provide the above-mentioned motion control system of a three-coordinate measuring machine, and the motion control method specifically includes the following steps :

Step 1, the PC is connected to the motion controller through a serial bus to communicate, and the PC sends a control command to the motion controller;

Step 2. After receiving the control instruction, the motion controller generates a corresponding drive pulse signal and direction pulse signal and sends them to the pulse converter;

Step 3. After receiving the driving pulse signal and the direction pulse signal, the pulse converter converts it into a driving digital signal and sends it to the corresponding X-axis servo driver, Y-axis servo driver, and Z-axis servo driver;

Step 4. After the X-axis servo driver, Y-axis servo driver, and Z-axis servo driver receive the driving digital signal, they respectively drive the X-axis servo motor, Y-axis servo motor, and Z-axis servo motor to rotate to complete corresponding mechanical actions. Thereby driving the movement of the three axes of the three-coordinate measuring machine;

Step 5, the sensor collects general output signals and external feedback signals of the X-axis servo motor, Y-axis servo motor, and Z-axis servo motor, and sends them to the low-speed photocoupler and the high-speed photocoupler;

Step 6, the low-speed photoelectric coupler receives the general output signal, the general output signal includes limit switch signal, in-position signal, service alarm signal and emergency switch signal, and sends it to the motion controller after filtering; the high-speed photoelectric coupler The coupler receives the external feedback signal and sends it to the motion controller after electrical isolation. The external feedback signal includes the fault signal and the motor operation parameter signal. When these protection devices operate due to motor failure, it will send out a fault signal; the motor operating parameter signal is the environmental signal of the motor operation, such as operating current, temperature, vibration, speed, lubricating oil, liquid level, etc. It is converted into an analog signal by a transmitter and input to the PLC in the motion controller, etc.;

Step 7. The motion controller feeds back the real-time status of the CMM to the PC through the general output signal and the external feedback signal, so that the PC can perform scheduling.

The motion controller has two modes for outputting pulses: a fixed-length pulse output mode and a continuous pulse output mode, and the corresponding pulse output mode is selected by setting a register in the controller.

The communication mode between the PC and the motion controller is to carry out USB communication through the USB bus, and the USB realizes the communication between the PC and the motion controller, and feeds back the real-time state of the motion controller to the PC, so that the PC can control it, and at the same time The PC control signal is transmitted to the motion controller through the USB bus. The USB bus has developed rapidly because of its many advantages that the SIA and PCI buses cannot match, such as plug-and-play, hot-swappable, cost-effective, and expandable up to 127 controlled devices.

The three-coordinate measuring machine drives the workpiece to move in three directions through the movement of X, Y, and Z axes, and measures the workpiece. Based on the hardware selection of the motion control system, the present invention uses CoDeSys software to simulate the entire motion control system.

CoDeSys (Controlled Development System) is a controller platform software developed by German 3S company. Many automation companies at home and abroad (such as ABB, Bosch Rexroth, Leisai Technology, etc.) have adopted CoDeSys software to develop their own control system products.

As a programming system, CoDeSys has nothing to do with equipment. It is an environment for the complete development of programmable logic control PLC. When programmers program PLC, CoDeSys provides a relatively convenient method for the powerful IEC language. The debugger and editor of the programming system The processor function is based on a high-level programming language. CoDeSys not only supports the IEC61131-3 standard programming language, but also supports the real-time combination of C language and CoDeSys, and configures multiple controllers in the project accordingly.

CoDeSys supports five programming languages: Function Block Diagram (FBD), Structured Text (ST), Sequential Function Chart (SFC), Ladder Logic Diagram (LD), and Instruction List (IL). There are many languages to choose from when using, and the language is universal and can be used in various conditions. In addition, CoDeSys provides a continuous function chart (CFC) programming method.

The operating process of the present invention is as follows:

1. Preparation:

(1) Set the IP of the two network ports connected to the PC and the APAX-5580 motion controller;

(2) Install the SA1400 pulse converter device file;

Menu--Tools--Device Library--Installation,

The file type must be selected as "EtherCAT XML Device Description Configuration File"

Select Device Description Profile for SA1400 Pulse Converter

After installation, there is an SA1400 pulse converter device under the fieldbus--Ethercat--slave--Smartind... of the device library

2. New project Standard project SoftMotion CFC:

3. Set the PLC:

(1) Double-click Device

(2) Communication settings page, scan the network, select the scanned device

(3) PLC setting page, PLC settings area,

(4) "Always update variables" select "Enabel 2(always in bus cycle task)"

4. Add backplane and IO devices:

(1) Right mouse button Device, add special device-Backplane

(2) Login, scan Backplane, select device

5. Add SA1400 pulse converter:

(1) Right-click Device and select Add Device

(2) Fieldbus--Ethercat--master station--EhterCAT Master, button to add equipment

(3) Double-click the EtherCAT Master, and click the button Browse in the EtherCAT NIC Setting area of the "Slave" page

Select "CoDeSys EtherExpressGBit PCI Ethernet Adapter" connecting APAX-5580 motion controller and SA1400 pulse converter

In the Option area, check "Auto restart slaves"

(4) Power on the SA1400 pulse converter

Menu--Online--Login to

Right-click "EtherCAT_Master(EtherCAT Master)" and select Scan Device

(5) Menu - Online - Exit

Right-click "Smartind_Pluse_Module(SA1400)",

Select "Add SoftMotion CiA402Axis"

Add 3 axes

(6) Right-click on the three axes, select Properties, and rename them to AxisX-AxisZ

(7) Double-click the 3 axes, in "SoftMotion drive: scaling/mapping"

In the "Scaling" area, under the "Reverse direction" check box, the first data, enter the number of pulses per revolution of the stepper motor, here enter 400

6. Add CNC program:

Right click on Application--Add Object--CNC Program Din66025SMC_OutQueue

7. Write the program:

(1) Double-click PLC_PRG

(2) Add 3 axes

(3) Add 3 MC_Power operation blocks to control the enable state of the drive ("on" or "off")

(4) Add one SMC_Interpolator operation block

SMC_Interpolator is used to convert continuous paths into point information

(5) Add one SMC_TRAFO_Gantry3 operation block

(6) Add 3 SMC_ControlAxisByPos operation blocks

SMC_ControlAxisByPos is used to set the target position in the drive structure and is used in conjunction with the SMC_Interpolator function block.

8. Run

Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments we have described are only illustrative, rather than used to limit the scope of the present invention. Equivalent modifications and changes made by skilled personnel in accordance with the spirit of the present invention shall fall within the protection scope of the claims of the present invention.

Claims (9)

1. A motion control system of a three-coordinate measuring machine, characterized in that: the motion control system includes a PC, a motion controller, a pulse converter, an X-axis servo driver, a Y-axis servo driver, a Z-axis servo driver, an X Axis servo motor, Y-axis servo motor, Z-axis servo motor, three-coordinate measuring machine, sensor, low-speed photocoupler and high-speed photocoupler, the motion controller is connected with PC, pulse converter, low-speed photocoupler and The high-speed photocoupler is connected, and the pulse converter is respectively connected with the X-axis servo driver, the Y-axis servo driver and the Z-axis servo driver. The X-axis servo driver is connected to the three-coordinate measuring machine through the X-axis servo motor. The Y The axis servo driver is connected to the three-coordinate measuring machine through the Y-axis servo motor, the Z-axis servo driver is connected to the three-coordinate measuring machine through the Z-axis servo motor, and the sensors are respectively connected to the X-axis servo motor, Y-axis servo motor, and Z-axis Servo motor, low-speed photocoupler and high-speed photocoupler connection. 2. The motion control system of a three-coordinate measuring machine as claimed in claim 1, characterized in that: the motion control system also includes a drive state output circuit and a status indicator light, and the state indicator light passes through the drive state output circuit Connect to motion controller. 3. The motion control system of a three-coordinate measuring machine according to claim 1, wherein the model of the motion controller is APAX-5580. 4. The motion control system of a three-coordinate measuring machine according to claim 1, wherein the model of the pulse converter is SA1400. 5. The motion control system of a three-coordinate measuring machine according to claim 1, wherein the sensor is a grating ruler or an encoder. 6. A motion control method for a three-coordinate measuring machine, characterized in that: the motion control method needs to provide a motion control system for a three-coordinate measuring machine as claimed in claim 1, and the motion control method specifically includes the following step: Step 1, the PC is connected to the motion controller through a serial bus to communicate, and the PC sends a control command to the motion controller; Step 2. After receiving the control instruction, the motion controller generates a corresponding drive pulse signal and direction pulse signal and sends them to the pulse converter; Step 3. After receiving the driving pulse signal and the direction pulse signal, the pulse converter converts it into a driving digital signal and sends it to the corresponding X-axis servo driver, Y-axis servo driver, and Z-axis servo driver; Step 4. After the X-axis servo driver, Y-axis servo driver, and Z-axis servo driver receive the driving digital signal, they respectively drive the X-axis servo motor, Y-axis servo motor, and Z-axis servo motor to rotate to complete corresponding mechanical actions. Thereby driving the movement of the three axes of the three-coordinate measuring machine; Step 5, the sensor collects general output signals and external feedback signals of the X-axis servo motor, Y-axis servo motor, and Z-axis servo motor, and sends them to the low-speed photocoupler and the high-speed photocoupler; Step 6. The low-speed photocoupler receives the general output signal and sends it to the motion controller after filtering; the high-speed photocoupler receives the external feedback signal and sends it to the motion controller after electrical isolation Step 7. The motion controller feeds back the real-time status of the CMM to the PC through the general output signal and the external feedback signal, so that the PC can perform scheduling. 7. The motion control method of a three-coordinate measuring machine as claimed in claim 6, characterized in that: the motion controller output pulse has two modes: fixed-length pulse output mode and continuous pulse output mode, by setting the motion Register in the controller to select the corresponding pulse output mode. 8 . The motion control method of a three-coordinate measuring machine as claimed in claim 6 , wherein the communication mode between the PC and the motion controller is USB communication through a USB bus. 8 . 9. The motion control method of a three-coordinate measuring machine as claimed in claim 6, wherein the general output signal includes a limit switch signal, an in-position signal, a service alarm signal and an emergency switch signal, and the external feedback signal Signals include fault signals, motor operating parameter signals and ambient temperature signals.