Motion control system and its synchronization method

Abstract

The present application discloses a motion control system and its synchronization method. The motion control system includes a master station controller and multiple slave station controllers, which are connected through a real-time network between the master station controller and the slave station controllers; the slave station controller includes an I / O synchronization unit and at least one I / O device; the I / O synchronization unit includes a network signal processing module, a register, and a synchronization pulse generator; the network signal processing module acquires a frame synchronization signal generated by the local clock of the slave station controller; the register stores a delay time compensation value of the pre-configured I / O device; the synchronization pulse generator generates a synchronization pulse for the I / O device according to the frame synchronization signal and the delay time compensation value, so that the I / O device is synchronized with the real-time network. The present application generates a synchronization pulse for the I / O device through the I / O synchronization unit provided in the slave station controller, so that the I / O device is synchronized with the network traffic, thereby significantly improving the control performance.

Description

Technical Field

[0001] This application relates to the field of control technologies, and in particular, to a motion control system and its synchronization method. Background Art

[0002] Real-time Ethernet is widely used in motion control systems. Some protocols such as EtherCAT and PowerLink can achieve time synchronization with an accuracy less than 1 μs. However, the synchronization only involves data communication between the network master and slaves. Existing network solutions do not include motion control I / O (Input Output) synchronization (such as the output moment of PWM, the acquisition moment of the AD converter, etc.), which limits the achievable control performance. In high-performance multi-axis servo systems for applications such as robots and machine tools, the impact of synchronization uncertainty can be clearly seen. The variation of the time offset between motor control axes at the I / O level will have a direct and significant impact on the final three-dimensional positioning accuracy of the robot or machine tool. Summary of the Invention

[0003] The main objective of this application is to propose a motion control system and its synchronization method, aiming to solve the problem of I / O synchronization in the motion control system.

[0004] To achieve the above objective, in the first aspect of the embodiments of this application, a motion control system is provided. The motion control system includes a master controller and multiple slave controllers, and the master controller and the slave controllers are connected through a real-time network; each slave controller includes an I / O synchronization unit and at least one I / O device;

[0005] The I / O synchronization unit includes a network signal processing module, a register, and a synchronization pulse generator;

[0006] The network signal processing module is configured to obtain a frame synchronization signal generated by the local clock of the slave controller;

[0007] The register is configured to store a delay time compensation value of the I / O device pre-configured;

[0008] The synchronization pulse generator is configured to generate a synchronization pulse for the I / O device according to the frame synchronization signal and the delay time compensation value, so that the I / O device is synchronized with the real-time network.

[0009] In addition, to achieve the above objective, in the second aspect of the embodiments of this application, a synchronization method for a motion control system is provided. The motion control system includes a master controller and multiple slave controllers, and the master controller and the slave controllers are connected through a real-time network; each slave controller includes an I / O synchronization unit and at least one I / O device; the method includes:

[0010] Obtain the frame synchronization signal generated by the local clock of the slave controller;

[0011] Generate a synchronization pulse for the I / O device according to the frame synchronization signal and the delay time compensation value of the I / O device configured in advance, so that the I / O device is synchronized with the real-time network.

[0012] The motion control system and its synchronization method provided by the embodiments of the present application generate a synchronization pulse for the I / O device through the I / O synchronization unit set in the slave controller, so that the I / O device is synchronized with the network traffic, thereby significantly improving the control performance. Description of the Drawings

[0013] Figure 1 It is a schematic diagram of a typical EtherCAT network structure provided by the embodiments of the present application;

[0014] Figure 2 It is a schematic diagram of a motion control system provided by the embodiments of the present application;

[0015] Figure 3 It is a schematic diagram of an I / O synchronization unit in the motion control system provided by the embodiments of the present application;

[0016] Figure 4 It is a schematic diagram of a robot control system provided by the embodiments of the present application;

[0017] Figure 5 It is a schematic diagram of a frame synchronization signal and a PWM I / O synchronization pulse provided by the embodiments of the present application;

[0018] Figure 6 It is a schematic diagram of the synchronization method of the motion control system provided by the embodiments of the present application.

[0019] The implementation, functional features and advantages of the purpose of the present application will be further described with reference to the embodiments and the drawings. Detailed Embodiments

[0020] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0021] Now, the implementation of each embodiment of the present application will be described with reference to the drawings. In the subsequent description, the suffixes such as "module", "component" or "unit" used to represent elements are only for the convenience of description of the present application, and they have no specific meaning themselves.

[0022] In this application, the descriptions involving "first", "second", etc. are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. Additionally, the technical solutions between various embodiments may be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0023] First Embodiment:

[0024] Before elaborating on this embodiment, the following is combined with Figure 1 to elaborate in detail on the problems existing in the prior art:

[0025] As Figure 1 shown in the schematic diagram of the typical EtherCAT network structure, the distributed clock mechanism enables all EtherCAT devices to use the same system time, thereby controlling the synchronous execution of each device's tasks. The slave device can generate a synchronous signal based on the synchronous system time for interrupt control or triggering the input and output of data.

[0026] To explain the limitations of the existing solutions, consider a two-axis network motion control system. The motion control host sends commands and command values to two servo controllers through a real-time network, and each servo controller constitutes a slave node on the network. The servo controller itself consists of a network controller, a motor controller, a power inverter, a motor / encoder, etc.

[0027] The real-time network protocol uses different methods to synchronize the slave nodes with the host. A commonly used method is to configure a local synchronous clock at each node and keep the master clock and each slave clock synchronized through the distributed clock mechanism, and then synchronize the command values and commands of all servo axes based on this clock. However, it is not enough to transmit the synchronous data to the motor controller. The motor controller must also be able to respond in a synchronous manner. Without this ability, the motor controller cannot fully utilize the timing accuracy of the real-time network. When responding to the command values and commands, since each I / O in the motor controller (e.g., PWM timer and ADC) has an inherent delay and time quantization, the synchronization of the I / O of the motor controller is very important.

[0028] As Figures 2 - 3As shown in the figure, the first embodiment of the present application provides a motion control system. The motion control system includes a master controller 10 and a plurality of slave controllers 20, and the master controller 10 and the slave controllers 20 are connected through a real-time network 30; the slave controller 20 includes an I / O synchronization unit 202 and at least one I / O device 203.

[0029] In this embodiment, the slave controller 20 further includes a network communication module 201 communicatively connected to the master controller 10;

[0030] The I / O synchronization unit is arranged between the network communication module 201 and the I / O device 203.

[0031] In this embodiment, the real-time network 30 is a real-time Ethernet, and the real-time Ethernet includes at least one of EtherCAT, PowerLink, PROFINET, and SERCOS II.

[0032] The I / O synchronization unit 202 includes a network signal processing module 2021, a register 2022, and a synchronization pulse generator 2023;

[0033] The network signal processing module 2021 is configured to obtain a frame synchronization signal generated by the local clock of the slave controller 20;

[0034] The register 2022 is configured to store a delay time compensation value of the I / O device 203 pre-configured;

[0035] The synchronization pulse generator 2023 is configured to generate a synchronization pulse of the I / O device 203 according to the frame synchronization signal and the delay time compensation value, so that the I / O device 203 is synchronized with the real-time network 30.

[0036] In one embodiment, the register 2022 is further configured to store the number of synchronization pulses;

[0037] The synchronization pulse generator 2023 is further configured to generate a synchronization pulse of the I / O device 203 according to the frame synchronization signal, the delay time compensation value, and the number of synchronization pulses.

[0038] To better illustrate this embodiment, the following takes a robot control system as an example and combines Figures 4 - 5 for illustration:

[0039] Such as Figure 4The shown robot control system. The host sends commands and command values to the servo drive via EtherCAT, and then controls the servo motor to drive the robot, such as: robot joints. The host constitutes the master station on the network, and the servo drive constitutes a slave station on the network. The servo drive itself consists of an EtherCAT module, a position loop, a speed loop, a current loop, a current-voltage sampling module, an encoder interface, a PWM generation module, a motor drive module, etc.

[0040] To make the PWM generation module in the servo drive keep in sync with the network traffic, an I / O synchronization unit is added between the EtherCAT module and the PWM generation module. The I / O synchronization unit obtains the frame synchronization signal generated by the local clock, and generates a synchronization pulse according to the frame synchronization signal and the pre-configured delay time compensation value. The synchronization pulse is output to the PWM generation module to trigger the generation of the required final signal.

[0041] As Figure 5 shown in the schematic diagram of the relationship between the synchronization pulse and the frame synchronization signal, t frame is the period of the frame synchronization signal; t d is the pre-configured delay time to compensate for the delay difference of the PWM I / O; t PWM is the period of the PWM pulse, t jitter is the jitter time of the frame synchronization signal.

[0042] When configuring the system parameters, the following steps can be taken:

[0043] 1) Measure the delay time of the PWM I / O, and select the maximum delay as the common delay time t d-com ;

[0044] 2) Measure the jitter time of the frame synchronization signal, and take its maximum value as t jitter ;

[0045] 3) Configure the delay time compensation value of the PWM I / O in the system as t d-com minus the delay time of the PWM I / O itself;

[0046] 4) The period of the pulses required by the PWM I / O is determined and configured according to its own needs. The actual number of pulses is The symbol is floor;

[0047] 5) Configure the above parameters into the I / O synchronization unit.

[0048] The time synchronization of other I / Os can refer to the above PWM I / O, which will not be elaborated here.

[0049] The motion control system provided by the embodiment of the present application generates a synchronization pulse for the I / O device through the I / O synchronization unit set in the slave controller, so that the I / O device is synchronized with the network traffic, thereby significantly improving the control performance.

[0050] Second Embodiment:

[0051] As Figure 6 shown, the second embodiment of the present application provides a synchronization method for a motion control system. The motion control system can refer to the content described in the first embodiment, which will not be elaborated here.

[0052] The synchronization method of the motion control system includes the steps:

[0053] S11. Obtain the frame synchronization signal generated by the local clock of the slave controller;

[0054] S12. Generate a synchronization pulse for the I / O device according to the frame synchronization signal and the pre-configured delay time compensation value of the I / O device, so that the I / O device is synchronized with the real-time network.

[0055] In an embodiment, the generating the synchronization pulse for the I / O device according to the frame synchronization signal and the pre-configured delay time compensation value of the I / O device includes:

[0056] Generate the synchronization pulse for the I / O device according to the frame synchronization signal, the pre-configured delay time compensation value of the I / O device, and the pre-configured number of synchronization pulses.

[0057] In an embodiment, the delay time compensation value of the I / O device is configured in the following manner:

[0058] Measure the delay time of the I / O device, and select the maximum delay time as the common delay time;

[0059] Configure the difference between the common delay time and the delay time of the I / O device itself as the delay time compensation value of the I / O device.

[0060] In an embodiment, the number of synchronization pulses is configured in the following manner:

[0061] Calculate the difference between the period of the frame synchronization signal and the delay time compensation value;

[0062] Calculate the ratio of the difference to the period of the synchronization pulse, and configure the integer part of the ratio as the number of synchronization pulses.

[0063] In an embodiment, the calculating the difference between the period of the frame synchronization signal and the delay time compensation value includes:

[0064] Measure the jitter time of the frame synchronization signal;

[0065] Calculate the sum of the period of the frame synchronization signal and the jitter time, and calculate the difference between the sum and the delay time compensation value.

[0066] The synchronization method of the motion control system provided by the embodiment of the present application generates a synchronization pulse for the I / O device through the I / O synchronization unit set in the slave controller, so that the I / O device is synchronized with the network traffic, thereby significantly improving the control performance.

[0067] It should be noted that in this article, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the presence of additional identical elements in the process, method, article or device including the element.

[0068] The above are only the preferred embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A motion control system, characterized in that, The motion control system includes a master controller and multiple slave controllers, which are connected through a real-time network; the slave controller includes an I / O synchronization unit and at least one I / O device; The I / O synchronization unit includes a network signal processing module, a register, and a synchronization pulse generator; The network signal processing module is used to obtain the frame synchronization signal generated by the local clock of the slave controller; The register is used to store the delay time compensation value of the pre-configured I / O device; the delay time compensation value of the I / O device is configured in the following way: measure the delay time of the I / O device, select the maximum delay time as the common delay time; configure the difference between the common delay time and the delay time of the I / O device itself as the delay time compensation value of the I / O device; The synchronization pulse generator is used to generate the synchronization pulse of the I / O device according to the frame synchronization signal and the delay time compensation value, so that the I / O device is synchronized with the real-time network; The register is also used to store the number of synchronization pulses; The synchronization pulse generator is also used to generate the synchronization pulse of the I / O device according to the frame synchronization signal, the delay time compensation value, and the number of synchronization pulses.

2. The motion control system according to claim 1, wherein The real-time network is a real-time Ethernet, and the real-time Ethernet includes at least one of EtherCAT, PowerLink, PROFINET, and SERCOSII.

3. The motion control system according to claim 1, characterized in that, The slave controller further includes a network communication module communicatively connected to the master controller; The I / O synchronization unit is arranged between the network communication module and the I / O device.

4. A synchronization method for a motion control system, the motion control system comprising a master station controller and a plurality of slave station controllers, and the master station controller and the slave station controllers being connected through a real-time network; The slave controller includes an I / O synchronization unit and at least one I / O device; characterized in that The method includes: Obtain the frame synchronization signal generated by the local clock of the slave controller; Generate the synchronization pulse of the I / O device according to the frame synchronization signal and the pre-configured delay time compensation value of the I / O device, so that the I / O device is synchronized with the real-time network; The delay time compensation value of the I / O device is configured in the following way: Measure the delay time of the I / O device, select the maximum delay time as the common delay time; Configure the difference between the common delay time and the delay time of the I / O device itself as the delay time compensation value of the I / O device; The generating the synchronization pulse of the I / O device according to the frame synchronization signal and the pre-configured delay time compensation value of the I / O device includes: Generate the synchronization pulse of the I / O device according to the frame synchronization signal, the pre-configured delay time compensation value of the I / O device, and the pre-configured number of synchronization pulses.

5. The synchronization method of the motion control system according to claim 4, wherein The number of synchronization pulses is configured in the following way: Calculate the difference between the period of the frame synchronization signal and the delay time compensation value; Calculate the ratio of the difference to the period of the synchronization pulse, and configure the integer part of the ratio as the number of synchronization pulses.

6. The synchronization method of the motion control system according to claim 5, characterized in that, Calculating the difference between the period of the frame synchronization signal and the delay time compensation value includes: Measuring the jitter time of the frame synchronization signal; Calculating the sum of the period of the frame synchronization signal and the jitter time, and calculating the difference between the sum and the delay time compensation value.

7. The synchronization method of the motion control system according to claim 4, characterized in that, The real-time network is a real-time Ethernet, and the real-time Ethernet includes at least one of EtherCAT, PowerLink, PROFINET, and SERCOSII.

Images