Gantry system synchronous control method and device

Abstract

The invention discloses a gantry system synchronous control method and device, relates to the field of gantry control, and aims to solve the problem of clock inconsistency of a gantry main shaft driver and a slave shaft driver. The method comprises the following steps: the main shaft driver sends a current clock pulse signal of a main shaft to the slave shaft driver through a clock pulse cable; the slave shaft driver compares the received current clock pulse signal of the main shaft with the current clock pulse signal of the slave shaft to generate a current clock pulse signal compensation value t1, the next clock pulse signal of the slave shaft is advanced by t1, and the self clock pulse signal of the slave shaft is adjusted once every fixed period; and after slave shaft clocks are aligned, a gantry synchronization algorithm is operated to perform master-slave shaft synchronization control. The clock consistency of the master and slave shafts can be realized, and the synchronous control performance of the master and slave shafts is further improved.

Description

Technical Field

[0001] The present invention relates to the field of gantry control, and particularly to a synchronous control method and device for a gantry system. Background Art

[0002] In industrial applications, numerically controlled machine tools with a gantry frame structure are widely used for processing large and heavy parts to meet the requirements of large-size processing. To achieve high-performance motion control of a gantry machine tool, generally, the gantry axis adopts a dual-motor coordinated drive method. For the control of such a dual-drive system, it is necessary to make the gantry frame track the desired motion trajectory as much as possible to achieve its servo tracking function, and at the same time ensure the coordinated motion between the two servo drive motors to achieve its synchronous control function. Therefore, it is particularly important to design and develop a gantry synchronous control method that can ensure the synchronous performance between the master and slave axes.

[0003] Currently, there are mainly two hardware solutions for the mainstream gantry synchronous control method. One is to connect the position feedback frequency division output of the main axis servo driver to the pulse input interface of the slave axis driver. In this way, the slave axis driver uses the position feedback increment of the main axis driver as the position command to move, ensuring position synchronization. This method has complex wiring, and at the same time, the lag of the interactive data between the master and slave axes is poor, resulting in a poor synchronization effect. The other generally uses a 485 communication interface to interconnect the master and slave axes. The main axis receives the position feedback of the slave axis through a dedicated communication interface and sends the synchronization compensation amount to the slave axis through communication. This method has a relatively fast communication rate, but due to the inconsistency between the main axis driver clock and the slave axis driver clock, the synchronous performance of the two is not optimized. Summary of the Invention

[0004] The purpose of the present invention is to propose a synchronous control method for a gantry system to solve the problem of clock inconsistency between the gantry main axis driver and the slave axis driver. The gantry system consists of a controller, a main axis servo driver, a main axis servo motor, a slave axis servo driver, a slave axis servo motor, a gantry communication cable, and a clock pulse cable. The synchronous control method for the gantry system includes the following steps:

[0005] S1. Set a fixed period. The main axis and the slave axis generate a clock pulse signal every fixed period. The main axis driver sends the current clock pulse signal of the main axis to the slave axis driver through the clock pulse cable. The slave axis driver compares the received current clock pulse signal of the main axis with the current clock pulse signal of the slave axis to generate the current clock pulse signal compensation value t 1 , and advance the next clock pulse signal of the slave axis by t 1 . The slave axis adjusts its own clock pulse signal once every fixed period to achieve clock alignment of the slave axis;

[0006] S2. After the alignment of the slave axis clock is completed, send the gantry handshake message. After the main axis receives the gantry handshake message, start periodic communication. The slave axis receives the position command, the gantry speed command compensation amount, and the gantry torque command compensation amount sent by the main axis, and sends the slave axis position feedback and speed feedback to the main axis to generate the position deviation and speed deviation of the master and slave axes. If the position deviation between the master and slave axes is less than the set value, generate the gantry speed command compensation amount and the gantry torque command compensation amount and send them to the slave axis; if the position deviation between the master and slave axes is greater than or equal to the set value, alarm and stop the machine and send an alarm message to the slave axis.

[0007] Further, the fixed period is set to four times the control period:

[0008] Δt = 4t 0

[0009] where Δt represents the fixed period and t 0 represents the control period.

[0010] Further, the slave axis adjusts its own clock pulse signal every fixed period.

[0011] Further, the main control chip of the main axis outputs a clock pulse signal to the differential signal driver chip of the main axis, converts the clock pulse signal into a differential signal and outputs it to the slave axis, and the differential line receiver of the slave axis converts the received differential signal into a clock pulse signal and inputs it to the main control chip of the slave axis.

[0012] Further, the main axis servo driver and the slave axis servo driver adopt a proportional-integral (PI) controller.

[0013] Further, the proportional-integral (PI) controller of the main axis servo driver includes: a position loop, a speed loop, a torque loop, a gantry position controller, and a gantry speed controller. The position loop receives the position command sent by the controller and the main axis position feedback. The speed loop receives the output of the position loop, the main axis speed feedback, and the gantry speed command compensation amount. The torque loop receives the output of the speed loop, the main axis torque feedback, and the gantry torque command compensation amount. The output of the torque loop is the control input of the main axis servo motor; the gantry position controller receives the deviation of the main and slave axis position feedback, and the gantry speed controller receives the deviation of the main and slave axis speed feedback; if the position deviation between the main and slave axes is less than the set value, the gantry position controller generates the gantry speed command compensation amount, and the gantry speed controller generates the gantry torque command compensation amount; if the position deviation between the main and slave axes is greater than or equal to the set value, alarm and stop the machine.

[0014] Further, the proportional-integral (PI) controller of the slave-axis servo driver includes a position loop, a speed loop, and a torque loop. The position loop receives the position command sent by the main spindle and the slave-axis position feedback. The speed loop receives the output of the position loop, the slave-axis speed feedback, and the gantry speed command compensation amount. The torque loop receives the output of the speed loop, the slave-axis torque feedback, and the gantry torque command compensation amount. The output of the torque loop is the control input of the slave-axis servo motor.

[0015] The present invention also provides a gantry system synchronous control device. The gantry system is composed of a controller, a main spindle servo driver, a main spindle servo motor, a slave-axis servo driver, a slave-axis servo motor, a gantry communication cable, and a clock pulse cable. The gantry system synchronous control device includes:

[0016] A clock alignment module, which is used to set a fixed period. The main spindle and the slave axis generate a clock pulse signal every fixed period. The main spindle driver sends the current clock pulse signal of the main spindle to the slave-axis driver through the clock pulse cable. The slave-axis driver compares the received current clock pulse signal of the main spindle with the current clock pulse signal of the slave axis to generate the current clock compensation value t 1 , and advances the next clock pulse signal of the slave axis by t 1 , and the slave axis adjusts its own clock pulse signal once every fixed period to achieve slave-axis clock alignment;

[0017] A gantry compensation module, which is used to send a gantry handshake message after the slave-axis clock alignment is completed. After receiving the gantry handshake message, the main spindle starts periodic communication. The slave axis receives the position command, the gantry speed command compensation amount, and the gantry torque command compensation amount sent by the main spindle, and sends the slave-axis position feedback and speed feedback to the main spindle to generate the position deviation and speed deviation between the main and slave axes. If the position deviation between the main and slave axes is less than the set value, the gantry speed command compensation amount and the gantry torque command compensation amount are generated and sent to the slave axis; if the position deviation between the main and slave axes is greater than or equal to the set value, an alarm is given, the machine is stopped, and an alarm message is sent to the slave axis.

[0018] The beneficial effects brought by the technical solution provided by the present invention are:

[0019] In the present invention, a clock pulse interface is designed between the main spindle servo driver and the slave-axis driver. The differential signal driving chip of the main spindle is used to convert the clock pulse signal into a differential signal and output it to the slave axis. The differential line receiver of the slave axis converts the received differential signal into a clock pulse signal and inputs it to the main control chip of the slave axis. The slave axis uses the clock of the main spindle as the reference clock and adjusts its own clock to align with the main spindle clock every fixed period, achieving the clock consistency between the main and slave axes and further improving the synchronous control performance of the main and slave axes. Description of the Drawings

[0020] Figure 1 is a schematic diagram of the gantry system according to an embodiment of the present invention;

[0021] Figure 2 is a flowchart of a synchronous control method for a gantry system according to an embodiment of the present invention;

[0022] Figure 3 is a schematic diagram of the principle of master-slave axis clock alignment according to an embodiment of the present invention, where Figure 3 (a) shows the clock pulse signals before the master-slave axis clock alignment, Figure 3 (b) shows the clock pulse signals after the master-slave axis clock alignment;

[0023] Figure 4 is a structural diagram of the master-slave axis clock pulse interface according to an embodiment of the present invention;

[0024] Figure 5 is a schematic diagram of the principle of the gantry synchronization module in the software part according to an embodiment of the present invention;

[0025] Figure 6 is a schematic diagram of the optimization effect of the master-slave axis clock consistency on the gantry synchronization control performance according to an embodiment of the present invention. Detailed implementation manners

[0026] To make the objectives, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

[0027] The schematic diagram of the gantry system according to the embodiment of the present invention is referred to Figure 1 , which is composed of a controller, a main axis servo driver, a main axis servo motor, a slave axis servo driver, a slave axis servo motor, a gantry communication cable, and a clock pulse cable. The controller sends a position command to the main axis servo driver. Communication occurs between the controller and the main axis servo driver. The gantry communication cable connects the gantry communication interfaces of the main axis and the slave axis, and the clock pulse cable connects the clock pulse interfaces of the main axis and the slave axis. In addition, the main axis driver and the slave axis driver drive the respective axis motors to rotate through the encoder interface and the power interface (UVW) respectively.

[0028] The flowchart of a synchronous control method for a gantry system according to the embodiment of the present invention is as Figure 2 , and specifically includes the following steps:

[0029] S1. Due to influencing factors such as frequency deviation and temperature drift of the crystal oscillators in their respective drivers, the clocks of the main axis driver and the slave axis driver are not aligned. Set a fixed period. The main axis and the slave axis generate a clock pulse signal every fixed period. The main axis driver sends the current clock pulse signal of the main axis to the slave axis driver through the clock pulse cable. The slave axis driver compares the received current clock pulse signal of the main axis with the current clock pulse signal of the slave axis to generate the current clock pulse signal compensation value t 1, advance the next clock pulse signal of the slave axis by t 1 , the main axis sends a clock pulse signal once every fixed period, and the slave axis adjusts its own clock pulse signal once every fixed period to achieve clock alignment between the main and slave axes.

[0030] In a preferred embodiment of the present invention, the fixed period is set to four times the control period: Δt = 4t 0 , where Δt represents the fixed period and t 0 represents the control period. The slave axis adjusts its own clock pulse signal once every fixed period.

[0031] For the schematic diagram of the principle of clock alignment between the main and slave axes in the embodiment of the present invention, refer to Figure 3 , where Figure 3 (a) shows the clock pulse signal before the clock alignment between the main and slave axes, Figure 3 (b) shows the clock pulse signal after the clock alignment between the main and slave axes. The clock pulse signals of three fixed periods of the main axis are respectively a 1 , b 1 , c 1 , and the corresponding clock pulse signals of the slave axis are respectively a 2 , b 2 , c 2 . The clock pulse signal a 1 of the main axis and the clock pulse signal a 2 of the slave axis differ by t 1 . At this time, the main axis driver will send the a 1 clock pulse to the slave axis driver through the clock pulse cable. After the slave axis driver receives the clock pulse signal a 1 of the main axis, it compares it with its own clock pulse signal a 1 to generate the current clock pulse signal compensation value t 1 . Advance the next clock pulse signal b 2 of the slave axis by t 1 to achieve clock alignment between the main and slave axes. After the slave axis receives the clock pulse signal of the main axis every fixed period, it compares it with its own clock pulse signal to generate the clock compensation value of the current period, thereby continuously adjusting its own clock to align with the clock of the main axis driver and achieving the consistency of the clocks of the main and slave axes.

[0032] In a preferred embodiment of the present invention, the main control chip (MCU) of the main axis outputs a clock pulse signal to the differential signal driver chip of the main axis, converts the clock pulse signal into a differential signal and outputs it to the slave axis, and the differential line receiver of the slave axis converts the received differential signal into a clock pulse signal and inputs it to the main control chip (MCU) of the slave axis. For the structural diagram of the clock pulse interface between the main and slave axes in the embodiment of the present invention, refer to Figure 4 .

[0033] S2. After the slave axis clock alignment is completed, send the gantry handshake message. After the master axis receives the gantry handshake message, start the periodic communication. The slave axis receives the position command, gantry speed command compensation amount, and gantry torque command compensation amount sent by the master axis in each control cycle, and sends the slave axis position feedback and speed feedback to the master axis to generate the position deviation and speed deviation between the master and slave axes. If the position deviation between the master and slave axes is less than the set value, generate the gantry speed command compensation amount and gantry torque command compensation amount and send them to the slave axis; if the position deviation between the master and slave axes is greater than or equal to the set value, alarm and stop the machine and send an alarm message to the slave axis.

[0034] The specific steps are described as follows:

[0035] Step 1. Send the gantry handshake message after the slave axis clock alignment is completed;

[0036] Step 2. After the master axis receives the gantry handshake message from the slave axis, start the communication of each control cycle between the master and slave axes;

[0037] Step 3. The slave axis sends its own position feedback and speed feedback in each control cycle, and at the same time receives the position command, gantry speed command compensation amount, and gantry torque command compensation amount sent by the master axis; the master axis receives the position feedback and speed feedback from the slave axis in each cycle, and generates the position deviation between the master and slave axes for position deviation detection;

[0038] Step 4. If the position deviation between the master and slave axes is less than the set value, the gantry position controller and gantry speed controller generate the gantry speed command compensation amount and gantry torque command compensation amount, and return to Step 3;

[0039] Step 5. If the position deviation between the master and slave axes is greater than the set value, immediately alarm and stop the machine and send an alarm message to the slave axis to achieve coordinated shutdown of the master and slave axes.

[0040] In the embodiment of the present invention, a gantry synchronization module is designed in the software part, and the principle is as Figure 5 shown. The master axis servo driver and the slave axis servo driver adopt a proportional-integral (PI) controller.

[0041] The proportional-integral (PI) controller of the main spindle servo drive includes: a position loop, a speed loop, a torque loop, a gantry position controller, and a gantry speed controller. The position loop, speed loop, torque loop, gantry position controller, and gantry speed controller of the main spindle all adopt PI control. The position loop receives the position command sent by the controller and the main spindle position feedback. The speed loop receives the output of the position loop, the main spindle speed feedback, and the gantry speed command compensation amount. The torque loop receives the output of the speed loop, the main spindle torque feedback, and the gantry torque command compensation amount. The output of the torque loop is the control input of the main spindle servo motor. The gantry position controller receives the deviation of the master-slave axis position feedback, and the gantry speed controller receives the deviation of the master-slave axis speed feedback. If the master-slave axis position deviation is less than the set value, the gantry position controller generates a gantry speed command compensation amount, and the gantry speed controller generates a gantry torque command compensation amount. If the master-slave axis position deviation is greater than or equal to the set value, an alarm is issued and the machine stops.

[0042] The proportional-integral (PI) controller of the slave axis servo drive includes: a position loop, a speed loop, and a torque loop. The position loop, speed loop, and torque loop of the slave axis all adopt PI control. The position loop receives the position command sent by the main spindle and the slave axis position feedback. The speed loop receives the output of the position loop, the slave axis speed feedback, and the gantry speed command compensation amount. The torque loop receives the output of the speed loop, the slave axis torque feedback, and the gantry torque command compensation amount. The output of the torque loop is the control input of the slave axis servo motor.

[0043] Schematic diagram of the optimization effect of the master-slave axis clock consistency on the gantry synchronization control performance in the embodiment of the present invention for reference Figure 6 , in the figure, t a represents the moment when the main spindle drive receives the position command sent by the controller, and t b represents the moment when the slave axis drive receives the main spindle message and sends its own position feedback and speed feedback; t c represents the moment when the master-slave axis drives execute the three-loop algorithm of the position loop - speed loop - torque loop; t d represents the moment when the master-slave axis drives complete the execution of the three-loop algorithm and output the voltage PWM signal; t e represents the moment when the main spindle drive receives the message sent by the slave axis and starts to execute the gantry synchronization algorithm; t f represents the moment when the main spindle finishes executing the gantry synchronization algorithm and sends the position command and the gantry compensation output.

[0044] When the master-slave axis clocks are aligned, the tasks executed by the master-slave axis drives at the same moment are basically the same. Therefore, the t c and t d moments of the master-slave axis are basically the same. When the main spindle receives the position command sent by the controller at the t a moment in control cycle 1, it is executed after a delay of one cycle, while the slave axis is at the t bAfter receiving the position command sent by the main shaft in control cycle 1 at a certain moment, it takes effect in the current cycle. In this way, it can be realized that the master and slave axis drivers respond to the position command sent by the controller at the same moment. At the same time, the slave axis driver can receive the latest position command sent by the main shaft in each control cycle, and there will be no situation of missed command reception. Therefore, the master-slave axis clock consistency can enable the master and slave axis drivers to respond to the position command sent by the controller in the same control cycle, achieving absolute synchronization of command reception.

[0045] At the same time, at time t of control cycle 1 of the main shaft e after receiving the slave axis message, it starts to execute the gantry synchronization algorithm, and at time t f after executing the gantry synchronization algorithm, it generates the gantry speed command compensation amount and the gantry torque command compensation amount, and these compensation amounts also take effect within the time from t c to t d Therefore, the master-slave axis clock consistency can enable the master and slave axes to simultaneously take effect the gantry speed command compensation and the gantry torque command compensation in the same control cycle, thereby further optimizing the performance of the gantry synchronization algorithm.

[0046] An embodiment of the present invention also proposes a gantry system synchronous control device. The gantry system is composed of a controller, a main shaft servo driver, a main shaft servo motor, a slave axis servo driver, a slave axis servo motor, a gantry communication cable, and a clock pulse cable. The gantry system synchronous control device includes:

[0047] A clock alignment module, which is used to set a fixed cycle. The main shaft and the slave axis generate a clock pulse signal every fixed cycle. The main shaft driver sends the current clock pulse signal of the main shaft to the slave axis driver through the clock pulse cable. The slave axis driver compares the received current clock pulse signal of the main shaft with the current clock pulse signal of the slave axis to generate the current clock compensation value t 1 , advance the next clock pulse signal of the slave axis by t 1 , and the slave axis adjusts its own clock pulse signal once every fixed cycle to achieve slave axis clock alignment;

[0048] A gantry compensation module, which is used to send a gantry handshake message after the slave axis clock alignment is completed. After the main shaft receives the gantry handshake message, it starts periodic communication. The slave axis receives the position command, the gantry speed command compensation amount, and the gantry torque command compensation amount sent by the main shaft, and sends the slave axis position feedback and speed feedback to the main shaft to generate the position deviation and speed deviation of the master and slave axes. If the position deviation between the master and slave axes is less than the set value, it generates the gantry speed command compensation amount and the gantry torque command compensation amount and sends them to the slave axis; if the position deviation between the master and slave axes is greater than or equal to the set value, it alarms and stops and sends an alarm message to the slave axis.

[0049] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A gantry system synchronous control method, wherein the gantry system is composed of a controller, a main axis servo driver, a main axis servo motor, a slave axis servo driver, a slave axis servo motor, a gantry communication cable, and a clock pulse cable, characterized in that: The following steps are involved: S1. Set a fixed cycle. The main axis and the slave axis generate a clock pulse signal every fixed cycle. The main axis driver sends the current clock pulse signal of the main axis to the slave axis driver through the clock pulse cable. The slave axis driver compares the received current clock pulse signal of the main axis with the current clock pulse signal of the slave axis, generates the current clock pulse signal compensation value t1, advances the next clock pulse signal of the slave axis by t1, and adjusts its own clock pulse signal once every fixed cycle to achieve slave axis clock alignment. S2. After the slave axis clock is aligned, a gantry handshake message is sent. After the master axis receives the gantry handshake message, it starts periodic communication. The slave axis receives the position command, gantry speed command compensation, and gantry torque command compensation sent by the master axis, and sends the slave axis position feedback and speed feedback to the master axis to generate the position deviation and speed deviation of the master and slave axes. If the position deviation of the master and slave axes is less than the set value, the gantry speed command compensation and the gantry torque command compensation are generated and sent to the slave axis; if the position deviation of the master and slave axes is greater than or equal to the set value, an alarm is triggered, the machine is shut down, and an alarm message is sent to the slave axis.

2. A gantry system synchronization control method according to claim 1, characterized in that: The fixed period is set to four times the control period: Δt=4t0 Among them, Δt represents the fixed period, and t0 represents the control period.

3. A gantry system synchronization control method according to claim 1, characterized in that: The slave axis adjusts its own clock pulse signal once every fixed period.

4. A gantry system synchronization control method according to claim 1, characterized in that: The main control chip of the main axis outputs the clock pulse signal to the differential signal driver chip of the main axis, converts the clock pulse signal into a differential signal and outputs it to the slave axis. The differential line receiver of the slave axis converts the received differential signal into a clock pulse signal and inputs it to the main control chip of the slave axis.

5. A gantry system synchronous control method according to claim 1, characterized in that: The main axis servo drive and the slave axis servo drive adopt proportional integral controller.

6. A gantry system synchronization control method according to claim 5, characterized in that: The proportional-integral controller of the spindle servo drive includes: a position loop, a speed loop, a torque loop, a gantry position controller, and a gantry speed controller. The position loop receives the position command and spindle position feedback sent by the controller, the speed loop receives the output of the position loop, the spindle speed feedback, and the gantry speed command compensation amount, the torque loop receives the output of the speed loop, the spindle torque feedback, and the gantry torque command compensation amount, and the output of the torque loop is the control input of the spindle servo motor; the gantry position controller receives the deviation of the master-slave axis position feedback, and the gantry speed controller receives the deviation of the master-slave axis speed feedback; if the master-slave axis position deviation is less than the set value, the gantry position controller generates the gantry speed command compensation amount, and the gantry speed controller generates the gantry torque command compensation amount; if the master-slave axis position deviation is greater than or equal to the set value, an alarm is issued and the machine is shut down.

7. A gantry system synchronous control method according to claim 5, characterized in that: The proportional-integral controller of the slave axis servo drive includes: a position loop, a speed loop, and a torque loop. The position loop receives the position command sent by the master axis and the slave axis position feedback. The speed loop receives the output of the position loop, the slave axis speed feedback, and the gantry speed command compensation amount. The torque loop receives the output of the speed loop, the slave axis torque feedback, and the gantry torque command compensation amount. The output of the torque loop is the control input of the slave axis servo motor.

8. A gantry system synchronization control device, the gantry system is composed of a controller, a main axis servo driver, a main axis servo motor, a slave axis servo driver, a slave axis servo motor, a gantry communication cable, and a clock pulse cable, characterized in that: include: The clock alignment module is used to set a fixed cycle. The main axis and the slave axis generate a clock pulse signal every fixed cycle. The main axis driver sends the current clock pulse signal of the main axis to the slave axis driver through the clock pulse cable. The slave axis driver compares the received current clock pulse signal of the main axis with the current clock pulse signal of the slave axis, generates the current clock compensation value t1, and advances the next clock pulse signal of the slave axis by t1. The slave axis adjusts its own clock pulse signal once every fixed cycle to achieve slave axis clock alignment. The gantry compensation module is used to send a gantry handshake message after the slave axis clock alignment is completed. After the main axis receives the gantry handshake message, it starts periodic communication. The slave axis receives the position command, gantry speed command compensation amount, and gantry torque command compensation amount sent by the main axis, and sends the slave axis position feedback and speed feedback to the main axis to generate the position deviation and speed deviation of the master and slave axes. If the position deviation of the master and slave axes is less than the set value, the gantry speed command compensation amount and the gantry torque command compensation amount are generated and sent to the slave axis; if the position deviation of the master and slave axes is greater than or equal to the set value, an alarm is issued, the machine is shut down, and an alarm message is sent to the slave axis.

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