Distributed Remote Measurement Module for Three-Coordinate and Four-Axis Measuring Machines Based on gLink-II Bus and its Implementation Method

Abstract

This invention discloses a distributed, off-site measurement module and its implementation method for a coordinate measuring machine (CMM) based on the gLink-II bus, relating to the field of measurement technology. The invention includes: a master station control unit, deployed within the industrial computer of the CMM, serving as the core control node for generating synchronous control commands, configuring operating parameters, parsing and processing grating ruler / encoder data, and interacting with the host computer via a PCIe interface; and a measurement module, deployed on the bed of the CMM's X, Y, Z, and C rotary axes, for acquiring corresponding axis encoder signals, grating ruler signals, GPIO signals, probe signals, and handheld device signals locally, and completing signal preprocessing and data framing. Through a collaborative working mechanism of distributed acquisition, bus synchronization, redundant transmission, and algorithm compensation, this invention achieves localized acquisition, synchronous transmission, and high-precision calibration of four-axis grating ruler / encoder data for the CMM.

Description

Technical Field

[0001] This invention relates to the field of measurement technology, specifically to a distributed remote measurement module for a coordinate measuring machine (CMM) based on the gLink-II bus and its implementation method. Background Technology

[0002] The coordinate measuring machine (CMM) is a core piece of equipment in the precision manufacturing field for detecting workpiece dimensions and geometric tolerances. Its measurement accuracy directly depends on the synchronization of data acquisition, transmission reliability, and signal integrity of the grating ruler / encoder.

[0003] Currently, coordinate measuring machines (CMMs) generally employ a centralized grating scale / encoder acquisition scheme. This involves transmitting the grating scale / encoder signals from the X, Y, and Z linear axes and the C rotary axis to a single control unit via long-distance cables. However, centralized acquisition requires the deployment of numerous long-distance transmission cables, resulting in heavy loads on the CMM's cable chains, complex wiring, and susceptibility to electromagnetic interference during transmission, leading to signal attenuation and waveform distortion. More critically, the inconsistent trigger delays of the four-axis signals transmitted via cables of varying lengths result in synchronization errors exceeding 1 second, failing to meet the demands of high-precision measurement.

[0004] Furthermore, long-distance cables are prone to fatigue fracture during reciprocating motion, and the fault point is difficult to locate, resulting in high maintenance costs; a signal transmission failure on one axis can paralyze the entire acquisition system. In addition, the centralized architecture has fixed hardware resources, making it difficult to adapt to the expansion needs of different numbers of axes and different types of encoders (incremental, absolute, sine and cosine). At the same time, core control chips, bus interface chips, and other components are mostly imported, resulting in poor supply chain security.

[0005] To address this, a distributed remote measurement module for a three-coordinate and four-axis measuring machine based on the gLink-II bus and its implementation method are proposed. Summary of the Invention

[0006] The purpose of this invention is to address the problems mentioned in the background section by providing a distributed remote measurement module for a three-coordinate and four-axis measuring machine based on the gLink-II bus and its implementation method.

[0007] To achieve the above objectives, the present invention specifically adopts the following technical solution: a distributed remote measurement module for a three-coordinate and four-axis measuring machine based on the gLink-II bus, comprising: The main station control unit is deployed in the industrial computer of the coordinate measuring machine. As the core control node, it is used to generate synchronous control commands, configure operating parameters, parse and process grating ruler / encoder data, and interact with the host computer through the PCIe interface. The measurement module is deployed on the bed of the X-axis, Y-axis, Z-axis and C-axis rotary axes of the coordinate measuring machine. It is used to collect the encoder signal, grating ruler signal, GPIO signal, probe signal and handheld device signal of the corresponding axis, and complete the signal preprocessing and data framing. The gLink-II bus transmission link adopts a dual-redundant ring network structure, connecting the master station control unit and the measurement module, and is used to realize high-speed bidirectional transmission of control commands, configuration parameters, grating ruler data and encoder data between the master station and the slave station. The master station control unit is a motion control card. The hardware includes domestic Fudan Micro SOC, Yutai Micro PHY, power supply, crystal oscillator, DDR, and Flash chip components. The domestic Fudan Micro SOC chip integrates gLink-II bus communication and master station control logic. The gLink-II bus interface supports RGMII interface expansion to adapt to dual redundant ring networks. The measurement module hardware includes domestic Ziguang FPGA, Yutai Micro PHY, power supply, crystal oscillator, and ADC chip components. The domestic Ziguang FPGA integrates the control logic of gLink-II bus slave communication and trigger / scan probe unit, GPIO unit, handheld device unit, grating ruler unit, and encoder unit. The grating ruler / encoder is compatible with incremental, sine, cosine, and absolute signals.

[0008] Furthermore, the grating ruler / encoder unit supports hot-swapping, and the master station control unit can automatically complete slave station topology discovery and parameter configuration.

[0009] Furthermore, the physical layer of the gLink-II bus transmission link uses a 125MHz differential clock with a jitter of 100ps, and the transmission medium is an industrial Ethernet cable; the data link layer is configured with (2,1,4) convolutional coding to implement error correction function, and the application layer adopts a 32-byte fixed frame format, with the frame structure including axis number identifier, synchronization mark, position data, status bit and check code.

[0010] Furthermore, the grating ruler / encoder interface supports TTL / RS422 differential signal input and is compatible with incremental, absolute, and sine / cosine protocol signals.

[0011] A method for implementing distributed remote measurement on a coordinate measuring machine (CMM) based on the gLink-II bus, using the aforementioned distributed remote measurement module, includes the following steps: S1: System initialization. The master station control unit sends topology commands through the gLink-II bus to complete the communication handshake with each slave station and obtain the axis number identifier and communication address. S2: The master station control unit receives the operating parameters sent by the host computer and synchronizes the configuration parameters to each slave station through the gLink-II bus; S3: The master station control unit synchronously sends acquisition commands to each slave station via the gLink-II bus; S4: After signal conditioning and filtering noise reduction preprocessing, the grating ruler / encoder unit of the slave station assembles frames according to the preset frame format; S5: Each slave station synchronously transmits the framed data back to the master station control unit through the gLink-II bus dual-redundant ring network. If the master link fails during transmission, it will automatically switch to the backup link. S6: The main station control unit receives data from the four-axis grating ruler / encoder, extracts position information by parsing the data frame, calls the error compensation algorithm to complete the data calibration, and uploads the calibrated valid data to the upper control system of the measuring machine. S7: Repeat steps S3-S6 to achieve continuous distributed cross-station measurement data acquisition and transmission. Furthermore, in step S3, the master station control unit sends instructions to each slave station synchronously via the gLink-II bus, and resends the instructions if a timeout occurs.

[0012] Furthermore, in step S5, the transmission rate of the gLink-II bus is 1Gbps, the data transmission efficiency is 90%, and the inter-station data transmission delay is 0.5s.

[0013] Furthermore, in step S6, the error compensation algorithm includes speed error compensation and network synchronization error compensation: speed error compensation is performed based on the speed information carried by the status bits in the data frame through a preset speed mapping model; synchronization error compensation is performed based on the four-axis network synchronization delay detection data.

[0014] Furthermore, in step S6, the master station control unit supports the dynamic addition and removal of slave stations. When a new slave station is added or replaced, the master station automatically completes the topology update and parameter reconfiguration.

[0015] The beneficial effects of this invention are as follows: This invention employs a distributed, off-site architecture, deploying measurement modules close to each axis of the machine bed, significantly shortening the signal transmission distance of the grating ruler / encoder and reducing cable redundancy and electromagnetic interference at the source. A dual-redundant ring network is constructed via the gLink-II bus, with the master station control unit broadcasting a synchronization signal at 1-second intervals. Each slave station is precisely locked in place via a clock synchronization module, achieving synchronized acquisition of four-axis data. Actual testing shows a four-axis grating ruler / encoder data synchronization error of 0.2ms and a single-axis data update cycle of 0.8s, far superior to the millisecond-level synchronization errors of traditional centralized solutions, effectively ensuring the consistency and accuracy of the measurement data.

[0016] This invention employs a gLink-II dual-redundant ring network architecture, with real-time hot standby between the primary and backup links. When the primary link fails, it automatically switches to the backup link with a switching time of 1 second and a transmission error rate of 10%.-9 This ensures uninterrupted data transmission, avoiding the risk of system paralysis due to a single point of failure in traditional solutions. Simultaneously, the measurement module supports hot-swapping, and the master station control unit can automatically complete slave station topology discovery and parameter configuration. Adding or replacing slave stations does not require a system restart, significantly improving maintenance convenience. Furthermore, the grating ruler / encoder interface is compatible with multiple signal types, including incremental, absolute, and sine / cosine signals, flexibly adapting to the expansion needs of measuring machines with different numbers of axes and different types.

[0017] The core hardware of this invention uses domestically produced components. The main station control unit uses domestically produced Fudan Micro SOC chips, the measurement module uses domestically produced Ziguang FPGA chips, and it is equipped with domestically produced Yutai Micro PHY chips, domestically produced ADC chips, domestically produced differential signal receiving chips, domestically produced crystal oscillators and power supply modules. This achieves full localization of the hardware chain from control chips to interface chips, freeing us from dependence on imported components and ensuring supply chain security. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall system architecture of the present invention; Figure 2 This is a schematic diagram of the hardware architecture of the GSN motion control card of the present invention; Figure 3 This is a schematic diagram of the hardware architecture of the measurement module of the present invention; Figure 4 This is a schematic diagram of the servo driver hardware architecture of the present invention; Figure 5 This is a schematic diagram of the servo motor hardware architecture of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0021] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0022] All electrical components mentioned in this article are connected to an external main controller and 220V AC mains power, and the main controller can be a conventional known device such as a computer that can control it.

[0023] In the description of the embodiments of the present invention, it should be noted that the terms "inner", "outer", "upper", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0024] like Figures 1 to 5 As shown, the present invention provides a distributed remote measurement module for a three-coordinate and four-axis measuring machine based on the gLink-II bus, including a master station control unit and a measurement module.

[0025] The main station control unit uses a Googol GSN motion control card, deployed within the industrial computer of the coordinate measuring machine (CMM) as the core control node. The hardware architecture of the main station control unit includes domestically produced Fudan Microelectronics SOC chips, Yutai Microelectronics PHY chips, power modules, crystal oscillators, DDR memory, and Flash memory; all core components are domestically produced.

[0026] The domestically produced Fudan Microelectronics SOC chip integrates a gLink-II bus master IP core, responsible for generating synchronization control commands, configuring operating parameters, and parsing and processing the grating ruler / encoder data transmitted from the slave stations. This SOC chip generates a 1-second synchronization signal via a built-in phase-locked loop (PLL), which is then synchronously distributed to each slave station via the gLink-II bus. The gLink-II bus interface supports RGMII interface expansion, connecting the main and backup links of a dual-redundant ring network via two RGMII interfaces, enabling real-time monitoring of link status and automatic fault switching.

[0027] The data cache module uses 256MB DDR2 SDRAM with an operating frequency of 800MHz. It achieves high-speed read and write control through the FPGA's built-in IP core to cache measurement data acquired continuously from four axes and prevent data loss.

[0028] The main station control unit and the host computer interact via a PCIe interface to enable parameter configuration and measurement data upload. The PCIe interface uses an x1 lane configuration with a transmission rate of 2.5GT / s, which can meet the real-time transmission requirements of high-speed measurement data.

[0029] Four measurement modules are configured, deployed on the bed of the X-axis, Y-axis, Z-axis (linear axes), and C-axis (rotary axes) of the coordinate measuring machine, respectively, to achieve local acquisition of signals from the grating ruler / encoder for each axis. The hardware architecture of each measurement module includes a domestically produced Ziguang FPGA chip, a Yutai Micro PHY chip, a power supply module, a crystal oscillator, an ADC chip, and a differential signal receiver chip; all core components are domestically produced.

[0030] The domestically produced Ziguang FPGA chip integrates a gLink-II bus slave IP core, responsible for receiving synchronization commands from the master station, implementing control logic processing for the trigger / scan probe unit, GPIO unit, handheld device unit, grating ruler unit, and encoder unit, and completing signal preprocessing and data framing. This FPGA chip uses a TQFP-144 package, has 20k LUTs of logic resources, and consumes only 0.8W, meeting the low-power and high-integration requirements of measuring machine field deployments.

[0031] The grating ruler / encoder interface module uses a domestically produced differential signal receiver chip, supporting TTL / RS422 differential signal input and compatible with incremental (A / B / Z phase), sine / cosine, and absolute (SSI protocol) signals. Specifically, for the X / Y / Z linear axes, an incremental grating ruler is used, outputting A / B phase orthogonal square wave signals with a resolution of 0.1m; for the C-axis rotary axis, an absolute encoder is used, outputting position data based on the SSI protocol with a single-turn resolution of 23 bits. The differential signal receiver chip incorporates a Schmitt trigger, which effectively suppresses common-mode interference, ensuring the integrity of signals transmitted over long distances.

[0032] The high-precision signal conditioning module uses a domestically produced ADC chip with a sampling rate of 500kHz, an input range of 2.5V, and a resolution of 0.1V. This ADC chip incorporates a programmable gain amplifier (PGA), which automatically adjusts the amplification factor according to the input signal amplitude, ensuring high-precision conversion and noise suppression of the grating ruler / encoder signal. The signal conditioning circuit employs a fourth-order Butterworth low-pass filter with a cutoff frequency of 200kHz, effectively filtering out high-frequency noise.

[0033] The clock synchronization module uses a 125MHz differential crystal oscillator with a frequency accuracy controlled within 30ppm. It receives the master clock calibration signal via the gLink-II bus and adjusts the local clock phase in real time to ensure synchronization accuracy with the master clock. Actual testing shows that the synchronization error between the slave clock and the master clock is 0.1s.

[0034] The gLink-II bus transmission link adopts a dual-redundant ring network topology. The master station control unit and four measurement modules are connected in series via industrial-grade shielded Ethernet cables to form a ring network. CAT6A shielded twisted-pair cable is used as the transmission medium, with a maximum transmission distance of 100 meters, meeting the requirements for remote deployment of the measurement equipment in the field.

[0035] The physical layer employs a 125MHz differential clock, with signal jitter controlled within 100ps, effectively reducing transmission delay fluctuations. The data link layer is configured with (2,1,4) convolutional coding, using coding gain to enhance electromagnetic interference immunity. The theoretical coding gain is 3.5dB, and the measured bit error rate is 10%. -9 The application layer uses a 32-byte fixed frame format. The frame structure includes an axis number identifier (8 bits), a synchronization flag (4 bits), position data (12 bits), status bits (4 bits), and a checksum (4 bits). The checksum uses the CRC-4 algorithm, with a generator polynomial of x. 4 +x+1 can detect single-bit and double-bit errors.

[0036] The dual-redundant ring network supports real-time monitoring of link status and automatic fault switching. The master station control unit periodically sends heartbeat frames to the primary link. If no response is received for three consecutive cycles, the primary link is determined to be faulty, and automatic switching to the backup link is initiated. The switching time is 1 second, ensuring uninterrupted data transmission.

[0037] This invention also provides a method for distributed, cross-station measurement of a coordinate measuring machine (CMM) based on the gLink-II bus, applied to the aforementioned measurement module, comprising the following steps: 1. System Initialization After the system powers on, the domestically produced Fudan Microelectronics SOC chip in the master station control unit initializes the gLink-II bus master IP core and broadcasts a topology discovery command via the gLink-II bus. Upon receiving the command, each measurement module (slave station) responds with its axis number identifier, encoder type (incremental / absolute), communication address, hardware version information, and device ID. After collecting all slave station responses, the master station establishes a slave topology table and completes the communication handshake.

[0038] The master station control unit receives operating parameters from the host computer via the PCIe interface, including the synchronization trigger cycle (default 1s), speed error compensation parameters (speed-position mapping table), and synchronization error threshold (default 0.2ms). The master station encapsulates these parameters into configuration frames according to axis number and sends them to the corresponding slave stations via the gLink-II bus. After receiving the configuration parameters, each slave station writes them to its local register and sends an acknowledgment message back to the master station. If the master station does not receive an acknowledgment message, it repeats the transmission until timeout, ensuring parameter configuration consistency.

[0039] 2. The domestically produced Fudan Microelectronics SOC chip in the master station control unit generates a synchronization signal with a period of 1 second through a built-in phase-locked loop. This synchronization signal is broadcast to each slave station via the gLink-II bus, with a transmission delay of 0.5 seconds. To ensure data acquisition synchronization, this embodiment adopts a dual mechanism of synchronization triggering + bus confirmation: after the master station sends the synchronization signal, it starts a timeout timer. If no confirmation feedback is received from each slave station within 0.5 seconds, the slave station is determined to have a communication abnormality and the synchronization signal is resent.

[0040] Each slave station locks onto the synchronization signal via a clock synchronization module, triggering acquisition on the rising edge of the synchronization signal. The grating ruler / encoder signal is converted into a single-ended signal by a differential receiver chip and then input to a high-precision signal conditioning module. The ADC chip performs analog-to-digital conversion on the signal at a sampling rate of 500kHz. The converted digital signal undergoes filtering and noise reduction preprocessing within the Ziguang FPGA. The filtering algorithm uses a moving average filter with a window length of 8, which can effectively suppress random noise without significantly increasing latency.

[0041] The preprocessed data is framed according to a preset 32-byte frame format. In the frame structure, the axis number identifier is used to distinguish the four-axis data (X-axis: 0x01, Y-axis: 0x02, Z-axis: 0x03, C-axis: 0x04), the synchronization flag is used to verify the validity of the acquisition timing (correspondence with the master station synchronization signal), the position data is 12 bits of valid position information, the status bit carries speed information, acquisition status and link status, and the checksum uses the CRC-4 algorithm to ensure data integrity.

[0042] 3. Each slave station synchronously transmits the framed measurement data back to the master control unit via the gLink-II bus. The bus transmission rate is 1Gbps, and the single frame transmission time is 256ns. Due to the use of a fixed frame format, the transmission overhead is low, and the measured data transmission efficiency is 90%.

[0043] A dual-redundant ring network monitors link status in real time. During normal operation, data is transmitted via the primary link, while the backup link is in hot standby mode. If the primary link fails (e.g., a broken network cable or PHY chip signal interruption), the system automatically switches to the backup link in 1 second. After the fault is recovered, the system automatically switches back to the primary link, ensuring continuous and reliable data transmission. Inter-station data transmission delay is 0.5 seconds, meeting the real-time requirements of four-axis synchronous acquisition.

[0044] 4. After receiving the quadcopter measurement data, the domestically produced Fudan Microelectronics SOC chip in the main station control unit parses the position data, speed data, status bits, and synchronization markers of each axis according to the frame format. To improve measurement accuracy, this embodiment integrates two algorithms: speed error compensation and network synchronization error compensation.

[0045] Velocity error compensation is based on the velocity information carried in the status bits of the data frame, and is performed through a pre-set velocity mapping model. The velocity mapping model is established in advance through calibration experiments, fitting the correspondence between velocity and position error, and the compensation amount is calculated using a piecewise linear interpolation method.

[0046] Synchronization error compensation is based on four-axis network synchronization delay detection data. The master station records the received timestamps of the data frames returned by each slave station, and calculates the network transmission delay of each slave station by combining this with the sent timestamp of the synchronization signal. Using the slave station with the smallest delay as the benchmark, interpolation compensation is performed on the position data of the other three axes to eliminate the measurement error introduced by the synchronization delay difference.

[0047] After error compensation, the calibrated position data error is 0.01m. The master station uploads the calibrated valid data to the upper control system of the measuring machine via the PCIe interface for workpiece dimension and geometric tolerance calculation.

[0048] 5. The master station continuously generates synchronization signals and repeats the above steps to achieve continuous distributed cross-station measurement data acquisition and transmission for the coordinate measuring machine (CMM). The synchronization cycle is 1 second, and the measured single-axis data update cycle is 0.8 seconds, meeting the requirements for high-speed measurement.

[0049] This embodiment supports hot-swapping of slave stations and dynamic topology updates. When a new or replaced slave measurement module needs to be added, a hot-swapping operation can be performed directly. The master station control unit periodically sends topology discovery commands. After detecting a change in a slave station, it automatically completes the address allocation and parameter configuration of the new slave station without requiring a system restart. In actual testing, the topology update and parameter configuration time after a slave station replacement is 3 seconds, significantly improving equipment scalability and maintenance efficiency.

[0050] This embodiment establishes a test platform to test the key performance indicators of the distributed off-site measurement module. The results are as follows: Test Project Design Specifications Measured value in conclusion Four-axis synchronization error 0.2ms 0.15ms qualified Single-axis data update cycle 1s 0.8s qualified Transmission error rate <![CDATA[10 -9 ]]> <![CDATA[2.810 -10 ]]> qualified Position error after calibration 0.01m 0.007m qualified Hot-swap response time 3s 2.1s qualified The test results above demonstrate that the distributed off-site measurement module and implementation method of this invention fully meet the design specifications. Compared to traditional centralized acquisition schemes, the four-axis synchronization error is improved from milliseconds to microseconds, significantly enhancing data transmission reliability. Simultaneously, it achieves complete domestic substitution of core hardware, effectively improving the measurement accuracy and operational stability of the coordinate measuring machine (CMM), making it suitable for high-precision inspection scenarios in the precision manufacturing field.

[0051] In summary: After the system is powered on, the master station control unit broadcasts a topology discovery command via the gLink-II bus. Each measurement module (slave station) responds with its own axis number identifier, encoder type, communication address, and hardware version information. Based on this, the master station establishes a slave station topology table and completes address allocation and parameter configuration, thus constructing a distributed acquisition network.

[0052] During continuous measurement, the master station control unit generates a synchronization signal with a period of 1 second through a built-in phase-locked loop, which is then broadcast to each slave station via the gLink-II bus. Each slave station's clock synchronization module uses a 125MHz differential crystal oscillator, receives the master station's clock calibration signal via the bus, adjusts the local clock phase in real time, locks the synchronization signal, and triggers the local grating ruler / encoder signal acquisition circuit uniformly on the rising edge of the synchronization signal.

[0053] The grating ruler / encoder signal is converted into a single-ended signal by a differential receiver chip and then input to a high-precision signal conditioning module. An ADC chip performs analog-to-digital conversion, and the converted digital signal undergoes filtering and noise reduction preprocessing within the FPGA. The preprocessed data is then framed according to a preset frame format. The frame structure includes axis number identifier, synchronization marker, position data, status bits, and checksum.

[0054] Each slave station transmits framed data back to the master control unit via a gLink-II dual-redundant ring network, with a bus transmission rate of 1Gbps. During normal operation, data is transmitted through the primary link, while the backup link is in hot standby mode. If the primary link fails, the system automatically switches to the backup link, with a switching time of 1 second.

[0055] After receiving the quadcopter measurement data, the domestically produced Fudan Microelectronics SOC chip in the main station control unit parses the position data, velocity data, and synchronization markers for each axis, and calls the error compensation algorithm to complete the data calibration. Error compensation includes velocity error compensation and network synchronization error compensation: velocity error compensation is based on the velocity information carried by the status bits and compensates through a preset velocity mapping model; synchronization error compensation is based on the quadcopter network synchronization delay detection data to eliminate measurement errors introduced by synchronization delay differences. The calibrated position data is uploaded to the measurement machine's upper control system via the PCIe interface.

[0056] Through the collaborative working mechanism of distributed acquisition, bus synchronization, redundant transmission, and algorithm compensation, this invention realizes the local acquisition, synchronous transmission, and high-precision calibration of data from the four-axis grating ruler / encoder of a coordinate measuring machine.

[0057] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A distributed remote measurement module for a three-coordinate and four-axis measuring machine based on the gLink-II bus, characterized in that: include: The main station control unit is deployed in the industrial computer of the coordinate measuring machine. As the core control node, it is used to generate synchronous control commands, configure operating parameters, parse and process grating ruler / encoder data, and interact with the host computer through the PCIe interface. The measurement module is deployed on the bed of the X-axis, Y-axis, Z-axis and C-axis rotary axes of the coordinate measuring machine. It is used to collect the encoder signal, grating ruler signal, GPIO signal, probe signal and handheld device signal of the corresponding axis, and complete the signal preprocessing and data framing. The gLink-II bus transmission link adopts a dual-redundant ring network structure, connecting the master station control unit and the measurement module, and is used to realize high-speed bidirectional transmission of control commands, configuration parameters, grating ruler data and encoder data between the master station and the slave station. The master station control unit is a motion control card. The hardware includes domestic Fudan Micro SOC, Yutai Micro PHY, power supply, crystal oscillator, DDR, and Flash chip components. The domestic Fudan Micro SOC chip integrates gLink-II bus communication and master station control logic. The gLink-II bus interface supports RGMII interface expansion to adapt to dual redundant ring networks. The measurement module hardware includes domestic Ziguang FPGA, Yutai Micro PHY, power supply, crystal oscillator, and ADC chip components. The domestic Ziguang FPGA integrates the control logic of gLink-II bus slave communication and trigger / scan probe unit, GPIO unit, handheld device unit, grating ruler unit, and encoder unit. The grating ruler / encoder is compatible with incremental, sine, cosine, and absolute signals.

2. The distributed remote measurement module for a three-coordinate and four-axis measuring machine based on the gLink-II bus according to claim 1, characterized in that, The grating ruler / encoder unit supports hot-swapping, and the master station control unit can automatically complete slave station topology discovery and parameter configuration.

3. The distributed remote measurement module for a three-coordinate and four-axis measuring machine based on the gLink-II bus according to claim 1, characterized in that, The physical layer of the gLink-II bus transmission link uses a 125MHz differential clock with a jitter of 100ps, and the transmission medium is an industrial Ethernet cable. The data link layer is configured with (2,1,4) convolutional coding to implement error correction. The application layer uses a 32-byte fixed frame format, and the frame structure includes axis number identifier, synchronization mark, position data, status bit and check code.

4. The distributed remote measurement module for a three-coordinate and four-axis measuring machine based on the gLink-II bus according to claim 1, characterized in that, The grating ruler / encoder interface supports TTL / RS422 differential signal input and is compatible with incremental, absolute, and sine / cosine protocol signals.

5. A method for distributed, cross-station measurement using a coordinate measuring machine (CMM) based on the gLink-II bus, characterized in that... The distributed off-site measurement module according to any one of claims 1-4 includes the following steps: S1: System initialization. The master station control unit sends topology commands through the gLink-II bus to complete the communication handshake with each slave station and obtain the axis number identifier and communication address. S2: The master station control unit receives the operating parameters sent by the host computer and synchronizes the configuration parameters to each slave station through the gLink-II bus; S3: The master station control unit synchronously sends acquisition commands to each slave station via the gLink-II bus; S4: After signal conditioning and filtering noise reduction preprocessing, the grating ruler / encoder unit of the slave station assembles frames according to the preset frame format; S5: Each slave station synchronously transmits the framed data back to the master station control unit through the gLink-II bus dual-redundant ring network. If the master link fails during transmission, it will automatically switch to the backup link. S6: The main station control unit receives data from the four-axis grating ruler / encoder, extracts position information by parsing the data frame, calls the error compensation algorithm to complete the data calibration, and uploads the calibrated valid data to the upper control system of the measuring machine. S7: Repeat steps S3-S6 to achieve continuous distributed cross-station measurement data acquisition and transmission.

6. The implementation method according to claim 5, characterized in that, In step S3, the master station control unit sends instructions to each slave station synchronously via the gLink-II bus, and resends the instructions if the timeout occurs.

7. The implementation method according to claim 5, characterized in that, In step S5, the transmission rate of the gLink-II bus is 1Gbps, the data transmission efficiency is 90%, and the data transmission delay between slave stations is 0.5s.

8. The implementation method according to claim 5, characterized in that, In step S6, the error compensation algorithm includes speed error compensation and network synchronization error compensation: speed error compensation is performed based on the speed information carried by the status bits in the data frame through a preset speed mapping model; synchronization error compensation is performed based on the four-axis network synchronization delay detection data.

9. The implementation method according to claim 5, characterized in that, In step S6, the master station control unit supports the dynamic addition and removal of slave stations. When a new slave station is added or replaced, the master station automatically completes the topology update and parameter reconfiguration.

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