CN115314534A - A Real-time Optimization Simulation Robot System Based on EtherCAT Communication Protocol - Google Patents

Abstract

The invention relates to the field of industrial robot simulation, in particular to a real-time optimization simulation robot system based on an EtherCAT communication protocol, which comprises the following steps: the front end displays the action of the entity robot through the screen interface; the back end is divided into a Linux non-real-time part and a Rtems real-time part according to the timeliness of task processing, is used for realizing the design of a control system communication platform, and is optimized by reasonably designing and developing EtherCAT master-slave station software frameworks, so that the problems of data fluctuation and data loss caused by the influence of external environmental factors are reduced; compared with the existing method depending on the hardware of the robot controller, the method has the advantages that the hardware cost is reduced, the better communication effect can be obtained, the practical application and popularization value is realized, the competitiveness of enterprises is improved, and the course heading is indicated for the robot industry.

Description

A real-time optimization simulation robot system based on EtherCAT communication protocol

technical field

The invention relates to the field of industrial robot simulation, in particular to a real-time optimized simulation robot system based on the EtherCAT communication protocol.

Background technique

Industrial robot is a multi-joint manipulator or multi-degree-of-freedom machine device developed for the industrial field. It relies on its own power and control force to execute the motion commands issued by the control system to achieve corresponding operations. It is mainly used for manufacturing, handling, testing, etc. Time-repetitive production links are also used in industrial fields such as automobile processing, electronic and electrical processing, and chemical industry. Compared with manpower, industrial robots can do some repetitive work with high intensity for a long time, which greatly liberates human resources, greatly improves productivity and reduces labor force, and accelerates the process of industrial production automation.

In the next 10 years, the development of industrial robots will develop in the direction of networking, intelligence, perception and human-machine collaboration. In a short period of time, industrial robots still need to vigorously research on precision, reliability, stability, and safety. As the application of industrial robots is becoming more and more widespread, the demand for robots in China is huge. Therefore, it is necessary to develop a robot control system with low cost and good openness using an open source platform. At the same time, the expensive price of physical robots is also a relatively large scientific research obstacle for researchers or schools. Through the above analysis and the problems existing in the teaching and training process of robots, it is necessary to invent a low-cost and adaptable robot. And a simulation system that can be universally applied to robots is the key.

For example, the Chinese patent No. 202010220622.0 is a non-real-time system-based EtherCAT master synchronization method. This patent provides a non-real-time system-based EtherCAT master synchronization method. The patent uses a non-real-time system and a soft master method of an ordinary network card. Because the timing precision of the non-real-time system is very poor, the communication is unstable, and it is easy to produce various connection or timeout errors.

For example, the Chinese patent No. 201810844014.X is a simulation device and simulation method for a robot system. This patent provides a simulation device for a robot system to simulate a virtual robot controller; this patent can only be used for robot controllers under certain conditions. The simulation is mainly used for applications, and the robot controller cannot be simulated from the bottom layer.

Contents of the invention

In order to solve the above problems, the present invention proposes a real-time optimization simulation robot system based on the EtherCAT communication protocol.

A real-time optimization simulation robot system based on EtherCAT communication protocol, including:

On the front end, the actions of the physical robot are displayed through the interface through the screen interface;

The backend is divided into Linux non-real-time part and Rtems real-time part according to the timeliness of task processing, which is used to realize the design of the communication platform of the control system.

The front end includes a human-computer interaction module that realizes 3D rendering of the physical robot through an interactive interface, a sampling data preprocessing module that records corresponding sampling data and screens and processes the data, and controls the position and posture of the physical robot and the front-end 3D robot at the same time. The pose synchronization module that changes, the path planning algorithm that develops and calls the path algorithm for the robot, and the rough interpolation module that uses the interpolation principle to perform rough interpolation on the acquired data information.

The man-machine interaction module rationally designs the interactive interface, and its software interface includes the parameters of the robot itself, the buttons for controlling the movement of each joint of the robot, and the position coordinates of the workpiece.

The sampling data preprocessing module refers to the value of the absolute position encoder and the application system I/O parameters of the robot's 6-axis joints and 2-axis displacement axis servo motors by the virtual control system when manual teaching and palletizing application functions are performed manually. Perform regular sampling, record the corresponding data and filter to obtain useful information.

The non-real-time part of Linux refers to a module that does not require high real-time performance, including an instruction transmission module that utilizes the perfect performance of Linux to process data transmission class corresponding application logic, and an instruction processing module that utilizes Linux to perform corresponding data processing; The real-time part of Rtems refers to modules that deal with high real-time requirements, including the data sampling module that obtains the position and attitude information of robot tools in Cartesian space, the joint fine interpolation module that uses real-time threads to perform fine interpolation on joint coordinates, The EtherCAT master communication module that outputs the interpolation data to each servo and I/O slave device through the EtherCAT bus.

The EtherCAT master station communication module includes a master station that uses an Ethernet controller to schedule the operation of the entire system, and a slave station that implements communication between the master station and the slave station and information transfer between the slave stations by the controller ESC. stand.

The application layer program of the master station realizes the configuration of the slave station node, sending and receiving tasks of mailbox data and process data by calling the API of IgH.

The described joint fine interpolation module is mainly realized in the DSP operation part in the EtherCAT frame; the plane formed by three points in the space is converted into a two-dimensional plane problem, and the interpolation optimization is performed on the plane using the Bezier curve principle, Finally, convert the interpolation point coordinates on the plane into three-dimensional point coordinates in space, combine rough interpolation, and perform "secondary" interpolation on the basis of it, given points x ₀ , x ₁ , x ₂ ,...,x _n , the Bezier curve can be derived as follows:

The servo drivers of the slave stations are all connected through the EtherCAT communication bus. The microprocessor of the slave station reads the control data from the ESC, and after receiving the data sent by the master station, it completes the set work tasks and realizes the device control function. .

In the process of measuring, calculating and analyzing the transmission delay, if the reference clock is that the data of the slave station is not interrupted internally, the interface types of the physical network ports of the slave station are the same during network transmission, that is, the transmission delay of the network cable is Uniform, and all slaves have the same processing delay, forwarding delay, and the difference between processing delay and forwarding delay;

Under the above assumptions, through derivation and induction, the transmission delay from the i-th slave station x to the reference slave station R is:

In the formula: t _d is the difference between processing delay and forwarding delay.

The beneficial effect of the present invention is: realize the development and use of robot controller simulator by rationally designing the microprocessor unit of simulation robot controller, thereby reduce unnecessary cost expenditure, and remove the development obstacle of developer; At the same time, by rationally designing and developing the EtherCAT master-slave software framework, it is optimized to reduce data fluctuations and loss problems due to the influence of external environmental factors; compared with existing methods that rely on robot controller hardware, this The invention can obtain better communication effects while reducing hardware costs, has practical application and promotion value, improves the competitiveness of enterprises and points out the navigation mark for the robot industry.

Description of drawings

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

Fig. 1 is a block diagram of the present invention;

Fig. 2 is a schematic diagram of the process structure of the present invention.

Detailed ways

In order to make the technical means, creative features, goals and effects achieved by the present invention easy to understand, the present invention will be further elaborated below.

As shown in Figure 1 and Figure 2, a real-time optimized simulation robot system based on the EtherCAT communication protocol includes:

On the front end, the actions of the physical robot are displayed through the interface through the screen interface;

The backend is divided into Linux non-real-time part and Rtems real-time part according to the timeliness of task processing, which is used to realize the design of the communication platform of the control system.

The real-time part of Rtems is a real-time multiprocessor system.

EtherCAT is Ethernet Control Automation Technology.

DSP is digital signal processing technology.

API is application programming interface.

ESC is the controller.

IgH is the main station framework, specifically the high ethercat master protocol stack.

Use pure software technology to simulate the hardware of the physical robot controller, run Igh in the real-time robot operating system Rtems, which is the main station framework, and realize the stability of data information transmission and ensure real-time performance by optimizing the communication between the EtherCAT master station and the slave station , and at the same time use the interpolation method to optimize the trajectory of the robot so that it can run more smoothly.

The system integrates EtherCAT master-slave station optimization technology, trajectory planning optimization technology and robot simulation technology, and solves the problem of intermittent and uneven robot trajectory planning in a complex external environment and the failure to achieve the desired trajectory.

Through software technology, the corresponding framework is built, and the micro-processing unit, peripheral drive unit, and storage unit of the physical robot controller are partially virtualized to form a virtualized robot controller system.

By rationally designing the microprocessor unit for simulating the robot controller, the development and use of the robot controller simulator can be realized, thereby reducing unnecessary costs and removing development obstacles for developers; at the same time, through reasonable design and development The EtherCAT master-slave station software framework is optimized to reduce data fluctuations and loss problems due to the influence of external environmental factors; compared with existing methods that rely on robot controller hardware, the present invention reduces hardware costs while reducing hardware costs It can obtain better communication effects, has practical application and promotion value, and at the same time improves the competitiveness of enterprises and points out the navigation mark for the robot industry.

The front end includes a human-computer interaction module that realizes 3D rendering of the physical robot through an interactive interface, a sampling data preprocessing module that records corresponding sampling data and screens and processes the data, and controls the position and posture of the physical robot and the front-end 3D robot at the same time. The pose synchronization module that changes, the path planning algorithm that develops and calls the path algorithm for the robot, and the rough interpolation module that uses the interpolation principle to perform rough interpolation on the acquired data information.

The pose synchronization module reduces the error between the expected pose and the actual pose as much as possible.

The man-machine interaction module rationally designs the interactive interface, and its software interface includes the parameters of the robot itself, the buttons for controlling the movement of each joint of the robot, and the position coordinates of the workpiece.

The sampling data preprocessing module refers to the value of the absolute position encoder and the application system I/O parameters of the robot's 6-axis joints and 2-axis displacement axis servo motors by the virtual control system when manual teaching and palletizing application functions are performed manually. Perform regular sampling, record the corresponding data and filter to obtain useful information.

The non-real-time part of Linux refers to a module that does not require high real-time performance, including an instruction transmission module that utilizes the perfect performance of Linux to process data transmission class corresponding application logic, and an instruction processing module that utilizes Linux to perform corresponding data processing; The real-time part of Rtems refers to modules that deal with high real-time requirements, including the data sampling module that obtains the position and attitude information of robot tools in Cartesian space, the joint fine interpolation module that uses real-time threads to perform fine interpolation on joint coordinates, The EtherCAT master communication module that outputs the interpolation data to each servo and I/O slave device through the EtherCAT bus.

The EtherCAT master station communication module includes a master station that uses an Ethernet controller to schedule the operation of the entire system, and a slave station that implements communication between the master station and the slave station and information transfer between the slave stations by the controller ESC. stand.

Integrating virtualization technology and EtherCAT communication master-slave station optimization technology to ensure real-time performance and stability while realizing the simulation of the robot controller, a new optimization technology scheme is proposed.

The application layer program of the master station realizes the configuration of the slave station node, the sending and receiving tasks of mailbox data and process data by calling the API of IgH.

The EtherCAT master communication module refers to outputting the interpolation data to each servo and I/O slave device through the EtherCAT bus.

The joint fine interpolation module refers to optimizing the speed and acceleration motion parameters of the application process according to the motion control principle, the system sends the discrete joint coordinates to the motion control system, and uses the real-time thread to perform fine interpolation on the joint coordinates .

The trajectory control of the robot is based on the kinematics theory of the robot, and the trajectory planning is optimized, focusing on the realization of the interpolation algorithm in the joint space to complete the smoothing of the trajectory of the robot.

The described joint fine interpolation module is mainly realized in the DSP operation part in the EtherCAT frame; the plane formed by three points in the space is converted into a two-dimensional plane problem, and the interpolation optimization is performed on the plane using the Bezier curve principle, Finally, convert the interpolation point coordinates on the plane into three-dimensional point coordinates in space, combine rough interpolation, and perform "secondary" interpolation on the basis of it, given points x ₀ , x ₁ , x ₂ ,...,x _n , the Bezier curve can be derived as follows:

On the basis of the kinematics theory of the robot, the trajectory planning optimization is carried out, and the interpolation algorithm in the joint space is emphatically realized.

The servo drivers of the slave stations are all connected through the EtherCAT communication bus. The microprocessor of the slave station reads the control data from the ESC, and after receiving the data sent by the master station, it completes the set work tasks and realizes the device control function. .

In the normal communication process, each cycle of EtherCAT communication only needs one or two frames to realize all the communication of all nodes, and can effectively process the receiving and sending of data. In order to realize the EtherCAT data frame communication, the present invention selects the IgH EtherCAT Master protocol stack, and the application layer program of the master station realizes the configuration of the slave station node, the sending and receiving tasks of mailbox data and process data by calling the API of IgH.

In the process of measuring, calculating and analyzing the transmission delay, if the reference clock is that the data of the slave station is not interrupted internally, the interface types of the physical network ports of the slave station are the same during network transmission, that is, the transmission delay of the network cable is Uniform, and all slaves have the same processing delay, forwarding delay, and the difference between processing delay and forwarding delay;

Under the above assumptions, through derivation and induction, the transmission delay from the i-th slave station x to the reference slave station R is:

In the formula: t _d is the difference between processing delay and forwarding delay.

Through the above calculation method, after obtaining the time delay from the slave station to the reference clock, put the obtained value into the corresponding register, and perform corresponding data processing in the corresponding register, and then complete the time compensation of the transmission delay.

Xenomai is a development framework based on the Linux kernel. It not only has strong real-time performance, but also has the characteristics of scalability, portability and maintainability. The strong real-time performance is mainly reflected in the addition of a real-time kernel, which coexists with the Linux kernel in the kernel space; Scalability, portability, and maintainability are mainly reflected in the fact that the Xenomai project not only provides dual-core, but also supports PREMPT-RT real-time preemption patches, while RT-Linux only allows real-time applications in the form of kernel modules, and Xenomai also supports users The application of space provides attention.

On this basis, use the idea of Xenomai dual-core to optimize the EtherCAT protocol. Based on the above considerations, Rtems real-time expansion is selected as the Linux real-time transformation solution. The overall framework of the EtherCAT software is divided into two parts: Linux non-real-time domain and Rtems real-time domain. part.

Corresponding method steps:

S1. Through the front-end platform, edit and debug the robot code, and generate an executable program for robot control;

S2. Through the network service program, receive the data request sent by the front end, call the optimization algorithm library class, and control the joint motion of the robot;

S3. Invoke the robot motion control algorithm to form a robot motion control scheme, robot control tasks, and motion trajectories;

S4. In the virtual robot controller, the data information of the robot is transmitted to the front end and the lower servo motor slave station equipment through the EtherCAT bus;

S5. Real-time display of robot motion control status and pose information on the 3D platform interface of the front-end solution, and the robot reproduces the application scene.

The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments, and what are described in the above-mentioned embodiments and description are only the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention also has various Variations and improvements all fall within the scope of the claimed invention. The protection scope of the present invention is defined by the appended claims and their equivalents.

Claims (10)

1. A real-time optimization simulation robot system based on an EtherCAT communication protocol is characterized in that: the method comprises the following steps:

the front end displays the action of the entity robot through the screen interface;

and the back end is divided into a Linux non-real-time part and an Rtems real-time part according to the timeliness of task processing and is used for realizing the design of a control system communication platform.

2. The EtherCAT communication protocol-based real-time optimization simulation robot system according to claim 1, wherein: the front end comprises a human-computer interaction module for realizing 3d rendering of the entity robot through an interaction interface, a sampling data preprocessing module for recording corresponding sampling data and screening the data, a pose synchronization module for controlling the entity robot and the front end 3d robot to change positions and poses at the same time, a path planning algorithm for developing and calling a path algorithm for the robot, and a coarse interpolation module for performing coarse interpolation on the acquired data information by using an interpolation principle.

3. The system according to claim 2, wherein the simulation system comprises: the human-computer interaction module reasonably designs an interaction interface, and the software interface comprises parameters of the robot, buttons for controlling the movement of each joint of the robot and a position coordinate part of a workpiece.

4. The system according to claim 2, wherein the simulation system comprises: when the sampling data preprocessing module manually performs a hand-held teaching stacking application function, the virtual control system performs timing sampling on the absolute position encoder values of the 6-axis joint and the 2-axis variable-displacement servo motor of the robot and the I/O parameters of the application system, records corresponding data and screens the data to acquire useful information.

5. The system according to claim 1, wherein the simulation system comprises: the Linux non-real-time part is a module with low real-time requirement, and comprises an instruction transmission module for processing corresponding application logic of data transmission class by using the perfect performance of Linux and an instruction processing module for performing corresponding data processing by using Linux; the Rtems real-time part is a module with high real-time processing requirement, and comprises a data sampling module for acquiring the position and posture information of the robot tool moving in a Cartesian space, a joint fine interpolation module for performing fine interpolation on joint coordinates by using a real-time thread, and an EtherCAT master station communication module for outputting interpolation data to each servo and I/O slave station device through an EtherCAT bus.

6. The EtherCAT communication protocol-based real-time optimization simulation robot system according to claim 5, wherein: the EtherCAT master station communication module comprises a master station which uses an Ethernet controller to schedule the operation of the whole system, and a slave station which is realized by a controller ESC and realizes the communication between the master station and the slave station and the information transfer between the slave stations.

7. The EtherCAT communication protocol-based real-time optimization simulation robot system according to claim 5, wherein: and the application layer program of the master station calls an API of the IgH to realize the tasks of configuration of the slave station nodes, and receiving and transmitting of mailbox data and process data.

8. The EtherCAT communication protocol-based real-time optimization simulation robot system according to claim 5, wherein: the joint fine interpolation module is mainly realized in a DSP operation component in an EtherCAT framework; converting a plane formed by three points in a space into a two-dimensional plane, performing interpolation optimization on the plane by using a Bezier curve principle, finally converting the coordinates of interpolation points on the plane into the coordinates of three-dimensional points in the space, combining coarse interpolation, performing 'secondary' interpolation on the basis of the coordinates, and giving a point x ₀ ,x ₁ ,x ₂ ,...,x _n The bezier curve can be derived as follows:

9. the EtherCAT communication protocol-based real-time optimization simulation robot system according to claim 5, wherein: the servo drivers of the slave stations are connected through an EtherCAT communication bus, the slave station microprocessor reads control data from the ESC, and after receiving the data sent by the master station, the slave station microprocessor finishes set working tasks to realize the equipment control function.

10. The EtherCAT communication protocol-based real-time optimization simulation robot system according to claim 5, wherein: in the process of measuring, calculating and analyzing the transmission delay, if the reference clock is that the data of the slave station is not interrupted inside, the interface types of the physical network ports of the slave stations are the same during network transmission, namely the transmission delay of the on-line network is uniform, and the processing delay, the forwarding delay, and the difference between the processing delay and the forwarding delay of all the slave stations are the same;

under the above assumption, the transmission delay from the ith slave station x to the reference slave station R is derived as follows:

in the formula: t is t _d The difference between the processing delay and the forwarding delay.

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