CN110561389A

CN110561389A - Assembly robot motion control method and device

Info

Publication number: CN110561389A
Application number: CN201910828466.3A
Authority: CN
Inventors: 高强
Original assignee: Suzhou Wave Intelligent Technology Co Ltd
Current assignee: Suzhou Wave Intelligent Technology Co Ltd
Priority date: 2019-09-03
Filing date: 2019-09-03
Publication date: 2019-12-13

Abstract

the invention provides an assembly robot motion control method and device. The method comprises the following steps: and the demonstrator acquires the motion trail of the assembly robot and sends the motion trail to the embedded system through a transmission control protocol. The sensor transmits the physical information of the tail end of the gripper of the assembly robot to the embedded system through the PCIe bus. The embedded system is connected with the motor driver through the CAN bus and sends motor control signals. Through the combination of multiple signal transmission technologies, the signal transmission requirements of different modules are met, the accuracy of motion track transmission and the real-time performance of sensor signal and control instruction signal transmission are improved, and the accuracy of the robot is improved.

Description

assembly robot motion control method and device

Technical Field

The invention relates to the field of automatic control, in particular to an assembly robot motion control method and device.

background

with the development of science and technology, the degree of industrial automation is gradually improved. There is also an increasing phenomenon of using an assembly robot instead of a worker in an industrial line. The assembly robot is an automatic machine for assembling parts, and generally comprises a mechanical structure, a motor module, a control system, a sensor module and the like, wherein the control system is studied most deeply. At present, an assembly robot control system is mainly a combination of a PC and a motion control card, a control instruction is input through the PC, and a motor is driven by the motion control card to move. The control to the assembly robot can be realized, and the assembly robot can replace workers to complete assembly actions. However, the PC and the motion control card themselves do not have high reliability, so that the existing assembly robot also does not have sufficient reliability. And also the cost of the assembly robot is too high because of the need for a dedicated motion control card.

Therefore, the embedded technology is applied to the assembly robot, and the embedded system is used for replacing a PC and an action control card, so that the cost is effectively reduced and the reliability is improved. The embedded system needs a plurality of modules to be matched, and the plurality of modules transmit control signals in a serial port mode and the like. Under the condition of large data volume, the problems of signal transmission delay, packet loss and the like can be caused, the assembly robot is difficult to control in time, and the instantaneity of the assembly robot is reduced. Secondly, due to the characteristic that the embedded system is relatively closed, when some new work needs to be finished by the assembling robot, a preset control program in the embedded system needs to be changed, the process is time-consuming and labor-consuming, and the flexibility of the assembling robot is greatly reduced.

Disclosure of Invention

In view of this, the invention provides an assembly robot motion control method and device, and aims to improve the real-time performance of a system and easily plan an action track by combining multiple signal transmission technologies and an embedded system.

Therefore, the technical scheme for solving the technical problem is as follows:

An assembly robot motion control method, the method comprising:

The embedded system receives the motion trail sent by the demonstrator through a control transmission protocol; wherein the motion trail is the motion trail of the tail end of the gripper of the assembly robot;

The embedded system generates a control instruction according to the motion track and the gripper tail end physical information measured by the high-speed serial computer expansion bus PCIe receiving sensor;

And the embedded system sends the control instruction to a plurality of motor drivers through a CAN bus.

Optionally, the teaching device sends the motion trail, and the teaching device comprises:

the demonstrator receives an action instruction;

The demonstrator analyzes and plans the action command to obtain the motion track;

And the demonstrator sends the motion trail to the embedded system through a Modbus-TCP protocol.

optionally, the physical information of the end of the paw measured by the sensor comprises:

Obtaining a three-dimensional coordinate by a three-dimensional dynamic displacement measuring instrument;

The force and moment obtained by the six-dimensional force sensor.

Optionally, the generating, by the embedded system, the control instruction according to the motion trajectory and the physical information at the end of the paw includes:

The embedded system calculates the displacement required by the movement of the paw according to the physical information of the end of the paw and the motion trail;

And the embedded system transcodes the displacement into control commands corresponding to the motors.

Optionally, the method further comprises:

the embedded system is connected with the programmable logic device on the production line through a 485 serial port and receives an assembly instruction.

Optionally, the embedded system is an industrial-grade embedded PC.

An assembly robot motion control apparatus, the apparatus comprising:

The control transmission protocol transceiving module is used for transceiving signals between the demonstrator and the embedded system;

PCIe bus module, is used for receiving and dispatching the signal between embedded system and the sensor;

the CAN bus module is used for transmitting and receiving signals between the motor driver and the embedded system;

And the data processing module is used for receiving the motion track and the terminal physical information of the paw and generating a motor driving signal.

Optionally, the control transmission protocol transceiver module is:

And the Ethernet communication module adopts a Modbus-TCP protocol.

optionally, the PCIe bus module includes:

the position acquisition module is used for receiving the three-dimensional coordinate value of the tail end of the paw sent by the three-dimensional dynamic displacement measuring instrument;

the PCI acquisition card module is used for receiving the contact force and the moment of the tail end of the paw sent by the six-dimensional force sensor;

And the PCIe transmission module is used for transmitting the physical information of the end of the paw, received by the position acquisition module and the PCI acquisition card module, to an embedded system.

optionally, the apparatus further includes a 485 serial module, configured to send an assembly instruction signal to the embedded system by the programmable logic device.

The invention provides a method and a device for transmitting signals of a robot control system of an assembly machine. And the demonstrator acquires the motion trail of the assembly robot and sends the motion trail to the embedded system through a transmission control protocol. The embedded system is connected with the motor driver through the CAN bus and sends motor control signals. By combining multiple signal transmission technologies, the signal transmission requirements of different modules are met, and the real-time performance of the system is improved. Secondly, the invention can also carry out the design and planning of the motion trail through the demonstrator, and can directly set the target motion trail of the assembly robot through the demonstrator, thereby further enhancing the flexibility of the assembly robot.

drawings

to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.

Fig. 1 is a flowchart of an assembly robot control signal transmission method according to an embodiment of the present invention.

fig. 2 is a flowchart of obtaining and sending a motion trajectory by the teach pendant according to an embodiment of the present invention.

Fig. 3 is a signal flow transmission path diagram of an assembly robot according to an embodiment of the present invention.

fig. 4 is a schematic diagram illustrating connection of modules of an assembly robot according to an embodiment of the present invention.

Detailed Description

at present, an assembly robot without adopting an embedded system has the defects of high cost and poor reliability, and the system is complex, so that great trouble is caused to the maintenance of the robot and the like. And generally do not have a real-time system and are relatively inflexible. The assembly robot adopting the embedded system solves the problems of poor reliability and overhigh cost to a certain extent, but still has better real-time performance. Secondly, due to the disadvantages of the embedded system, when a new action needs to be completed, the code needs to be changed from the embedded system, the process is complex, and the flexibility of the assembly robot is reduced.

In order to solve these problems, the embodiment of the present invention provides a method and an apparatus for transmitting a robot control signal of an assembly machine. The embedded system is adopted to reduce the cost and improve the reliability; the signal transmission is carried out through various local area networks with high real-time performance, such as a PCIe bus, a CAN bus and the like, so that the real-time performance of the system is improved; the embedded system can receive the motion trail sent by the demonstrator to carry out real-time control, and the flexibility of the assembly robot is improved.

The embodiment of the invention provides a motion control method and a motion control device for an assembly robot, and the following description is combined with the drawings in the specification to describe the preferred embodiment of the invention.

fig. 1 is a flowchart of a control signal transmission method according to an embodiment, including:

101: and the embedded system receives the motion trail sent by the demonstrator through a control transmission protocol.

Embedded systems (Embedded systems) are "application specific computer systems designed for specific applications that are fully Embedded within controlled devices" for controlling, monitoring or assisting equipment, machines or equipment used in plant operations. Unlike general-purpose computer systems such as personal computers, embedded systems typically perform predefined tasks with specific requirements. Because embedded systems can usually be targeted to only one specific task, designers can optimize it, reducing size and cost. Embedded systems are typically mass produced, so individual cost savings can be made, scaling up with yield by hundreds or thousands. Therefore, the embedded system is adopted as the control system of the assembly robot in the embodiment, the industrial production of the assembly robot is adapted, the production cost of the assembly robot can be effectively reduced, and the reliability of the assembly robot is improved.

However, in the existing embedded system, the program of the control system is generally solidified in the system component, that is, only some fixed actions can be completed, and when a new assembly task needs to be completed, the solidified control program in the embedded system needs to be changed.

In this embodiment, the embedded system may receive the motion trajectory sent by the demonstrator through a control transmission protocol. The motion trail can be an action designed in advance by a user, or can be a motion trail automatically generated by a demonstrator according to a motion key node given by the user. And the demonstrator sends the motion trail to an embedded system through a control transmission protocol. And after receiving the motion trail, the embedded system analyzes and analyzes the motion trail through a program cured in the embedded system.

102: and the embedded system generates a control instruction according to the motion trail and the physical information of the tail end of the paw measured by the PCIe receiving sensor through the high-speed serial computer expansion bus.

during the operation of the assembly robot, the end of the gripper of the assembly robot can be provided with corresponding sensors, which can comprise force sensors and displacement sensors. The method is used for collecting physical information of the end of the gripper of the assembly robot, and the physical information can be used for detecting faults, adjusting control commands and the like. For example, when the terminal of the paw is detected to be stressed excessively, the fault of the stressed sensor or the contact between the terminal of the paw of the assembly robot and a part of the part to be assembled is indicated, and the fault condition can be reported in time. Or some precise assembly tasks are completed by utilizing physical information, for example, a certain screw in the part can be reinforced through fixing torsion, so that the assembly firmness is ensured, and the part can be prevented from being damaged due to overlarge torsion.

In this embodiment, the embedded system receives the physical information measured by the sensor through the PCIe bus. PCIe bus is a high-speed serial computer expansion bus standard, belongs to high-speed serial point-to-point double-channel high-bandwidth transmission, connected devices distribute independent channel bandwidth and do not share bus bandwidth, mainly supports functions of active power management, error report, end-to-end reliable transmission, hot plug, service quality and the like, and is widely applied to aspects of storage devices, computer hardware and the like. That is, the PCIe bus has a larger bandwidth range and a larger data transmission frequency than the existing interfaces. I.e. the data transmission process has a higher real-time performance. The real-time performance of the assembly robot control signal transmission can be improved. Moreover, PCIe is a point-to-point transmission method, and in this embodiment, the gripper end physical information may be received in a form of a bus.

103: the embedded system sends control signals to the plurality of motor drivers through the CAN bus.

after receiving the motion trajectory sent by the demonstrator through the control transmission protocol, the embedded system in this embodiment may input the physical information of the gripper end and the motion trajectory, which are sent by the sensor through the PCIE bus, into the control software stored in the embedded system itself. And analyzing the motion track and the physical information by a control algorithm in the control software to obtain a final motor control instruction, and sending the motor control instruction to a plurality of motor drivers by a CAN bus.

The CAN bus, which was originally applied to the field of the automobile industry, is currently widely applied to various fields of industrial automation, belongs to the field of field buses, and is a serial communication network that effectively supports distributed control or real-time control. Compared with other transmission modes in a communication network in the existing automatic system, the real-time performance of data communication among all nodes of the network in the CAN bus is very high, data CAN be sent to the bus in a competition mode of bit-by-bit arbitration with a lossless structure according to the bus access priority, and different nodes CAN receive the same data at the same time. These features improve the real-time performance of data communication between nodes in a network formed by a CAN bus, and facilitate the formation of a redundant structure, which contributes to further improving the reliability and flexibility of the system.

the embodiment utilizes the high real-time performance of the CAN bus, so that the signals sent by the embedded system to the motor driver also have high real-time performance. The control command sent by the embedded system can be received by the motor driver in the assembly robot at the fastest speed.

Secondly, a plurality of motor drivers in this embodiment can control the assembly robot to work on a plurality of degrees of freedom, can realize the completion of complicated assembly task, promotes the flexibility of assembly robot.

In one embodiment, the number of the motor drivers is 7, which is greater than the number of degrees of freedom in a three-dimensional space, and the redundant motors can control the movement of the assembly robot in multiple degrees of freedom, so that the assembly robot can complete more complicated actions, and the flexibility of the assembly robot is further improved.

In order to further clarify the step of receiving the motion trail sent by the demonstrator by the embedded system through the control transmission protocol, the step is further described with reference to fig. 2

201: the demonstrator receives an action command sent by an operator.

in this embodiment, an operator or a developer of the assembly robot may first send the actions that the assembly robot needs to complete to the teach pendant in the form of action commands. The action command can be a plurality of key points in the action to be completed of the assembly robot, and can also be a path which is completely passed by the assembly robot in the action to be completed.

In the prior art, an action program of the assembly robot is pre-burnt into an embedded system, so that different actions cannot be flexibly completed according to instructions of operators, and the flexibility of the assembly robot is reduced. In the invention, an operator can simplify the actions to be finished and then send the actions to the demonstrator in the form of coordinate values of a plurality of action key points, thereby generating a motion track and finishing the control of the assembly robot.

202: the demonstrator analyzes and plans the action command to obtain the motion track

after receiving the action command, the demonstrator can analyze the action command to obtain a motion track. In this embodiment, the motion command may be some key points in the motion trajectory, which may indicate some positions that the assembly robot has to pass through in the current work task, and may also be used to determine some key dimensions between the parts in the assembly. However, whatever is represented, the keypoints are discrete, individual spatial coordinates and cannot form a complete, closed-loop motion trajectory. Only the coordinates of these key points are input, and it is difficult for the assembly robot to combine them for processing to obtain control commands.

Therefore, in the embodiment, the demonstrator can obtain the corresponding motion trail through a route planning mode and the like according to the key points and the actual situation of the assembly robot. For example, when there are two key points, the teach pendant may connect the initial position, the final position (generally coinciding with the initial position) and the two key points of the end of the gripper of the assembly robot by a straight line in a time relationship to obtain the corresponding motion trajectory. Or when a certain part which cannot move exists between two key points, a motion track moving from the edge of the part can be planned according to the shape of the current part.

In short, the embodiment does not limit the specific method for the demonstrator to analyze and plan the motion command, but indicates that the demonstrator in the embodiment can obtain a complete and closed-loop motion trajectory according to a relatively simple and discrete motion command.

203: the demonstrator sends the motion trail to the embedded system through a Modbus-TCP protocol

After the motion trail is obtained, the demonstrator can send the motion trail to the embedded system through a Modbus-TCP protocol. Mdobus is a standard industrial control data exchange protocol, in which Modbus-TCP converts each byte of binary data into a fixed two-bit hexadecimal string, and transmits the data in the form of TCP code. Meanwhile, the Modbus protocol and the TCP protocol have the advantages of easy application, high data transmission fault tolerance rate and strong transmission capability.

In this embodiment, the selection of the Modbus-TCP protocol for transmitting the motion trajectory is determined by the characteristics of the robot. The Modbus-TCP protocol has the characteristics of strong transmission capability and high fault tolerance rate, but is relatively insufficient in the aspect of real-time transmission. In the embodiment, the motion track transmitted by the demonstrator to the embedded system is the operation completed before the assembly robot works, and at this time, the assembly robot can be in a static state or complete the last command. Therefore, the assembly robot control system has low real-time requirements on motion trail transmission, and even can continue to perform subsequent operations after the current motion trail transmission is finished. The assembly robot in the embodiment belongs to a high-precision assembly robot, and can complete some high-precision assembly tasks. Therefore, the requirement on the precision of the motion track is extremely high, and the Modbus-TCP protocol is adopted for transmitting the motion track, so that a large amount of data can be sent to the embedded system accurately and faultlessly.

in one embodiment, the sensor measuring the physical information of the end of the paw comprises:

Receiving a three-dimensional coordinate obtained by a three-dimensional dynamic displacement measuring instrument through a data acquisition control system;

Receiving the force and the moment obtained by the six-dimensional force sensor through a data acquisition card;

in this embodiment, the end of the gripper of the assembly robot is provided with a six-dimensional force sensor and a three-dimensional dynamic displacement measuring instrument, wherein the six-dimensional force sensor is used for measuring the stress and moment conditions of the end of the gripper, and the three-dimensional dynamic displacement measuring instrument is used for measuring the three-dimensional position coordinates of the end of the gripper of the assembly robot. The embedded system receives the three-dimensional coordinates by using a data acquisition control system and receives the force and the moment by using a data acquisition card.

To further illustrate the method of signal transmission between the various systems, fig. 3 provides a signal flow transmission path diagram for an assembly robot, comprising:

the teach pendant 301 may send the motion trajectory to the embedded system 303 via Modbus-TCP protocol. The six-dimensional force sensor 302-2 can send the external force and external moment in three directions of the tail end of the paw to the embedded system through the PCIe bus. The three-dimensional dynamic displacement measurement instrument 302-1 may send the three-dimensional coordinates of the current position of the end of the assembly robot gripper to the embedded system via the PCIe bus. The internal software of the embedded system analyzes and calculates the motion track, the six-dimensional force and the three-dimensional coordinate to obtain a control instruction of the motor, and the control instruction is sent to the motor driver 304 through the CAN bus to control the motion of the motor.

In the embodiment, a six-dimensional force sensor and a three-dimensional dynamic displacement measuring instrument are adopted to measure physical information at the tail end of the gripper of the assembly robot, wherein the three-dimensional dynamic displacement measuring instrument can be an NDI-optotrak gait posture analysis system. Compared with the existing assembly robot technology, the method has the advantages that the sensors with higher precision are adopted to measure physical information, the combined external moment in three directions can be measured, and the assembly precision can be further improved.

Meanwhile, the PCIe bus is adopted to receive the physical information at the end of the paw in the embodiment, so that higher transmission bandwidth and higher bus frequency can be supported, and the transmission delay of the physical information is reduced to the maximum extent. The serial bus structure can receive data of a plurality of channels simultaneously. And because there is only one differential signal per direction in each lane, and because the clock information is embedded in the serial signal itself, there is no external clock signal, and the typical bandwidth of the serial signal is limited to the few gigahertz range. Further reducing the delay of signal transmission and improving the real-time performance of the system.

The assembly robot in the embodiment is a high-precision assembly robot and is used for completing some high-precision assembly tasks. Therefore, the requirement on the accuracy of the sensor in the embodiment is extremely high, and a six-dimensional force sensor and a three-dimensional dynamic displacement measuring instrument which are not adopted by the existing assembly robot are adopted to obtain the most accurate measurement result of the physical information of the end of the paw.

however, improving the accuracy of the assembly robot requires not only the sensor to be lifted. Because the assembly robot is actually in continuous motion during working, the physical information measured by the sensor has certain time variation. Therefore, physical information that is as real-time as possible is required to improve the assembly accuracy when the embedded system performs analysis processing. The signal transmission before the sensor and the embedded system is required to be as fast as possible, and the real-time performance of the system is improved. The PCIe bus has the characteristics of high real-time performance and large bandwidth, and can sufficiently meet the transmission requirement of the physical information at the tail end of the paw in the embodiment. Meanwhile, when the assembly action is finished, the control of the motor is required to be as accurate as possible, and the process that the embedded system sends a control command to the motor driver is required to be as short as possible, so that the time delay of the motor motion is reduced. The invention has more motors, so the CAN bus which has strong real-time performance and CAN simultaneously meet the requirement of a plurality of signal sending is adopted to transmit the control instruction.

In this embodiment, the internal software of the embedded system may perform calculation according to the received motion trajectory and the physical information to obtain a corresponding motor control instruction, and control a plurality of motors in the assembly robot to cooperate with each other to complete the assembly operation. For example, when the assembly robot is required to complete the assembly of a certain screw, some key action points can be produced according to a task to be assembled of the screw, and the teaching aid analyzes the key action points to obtain a corresponding motion track and sends the motion track to the embedded system through a Modbus-TCP protocol. The embedded system starts to move according to the motion track and the physical information of the tail end of the paw (the physical information can be zero before the operation is started), and collects the physical information of the tail end of the paw in real time. And when the three-dimensional position coordinate of the tail end of the paw returned by the three-dimensional dynamic displacement measuring instrument is coincident with a certain key position in the assembly motion trail, controlling the paw to grab the screw and move to the next key position. And when the current position coordinate is detected to coincide with a certain position in the motion trail again, assembling the screw. And when the torque moment at the tail end of the paw returned by the six-dimensional force sensor is detected to reach the assembly standard torque moment, controlling the assembly robot to stop assembly and returning to the initial position.

In one embodiment, the embedded system can be connected with a programmable logic device on a production line through a 485 serial port to receive assembly instructions.

The assembly robot in the embodiment can be applied to the fields of factory assembly lines and the like, and can quickly and accurately complete various assembly tasks. In practical application, parts on the assembly line are separated, a control system on the assembly line is required to send an assembly instruction to the assembly robot, and the assembly robot carries out assembly according to a preset motion track and the like.

In one embodiment, the embedded system sending control commands to the plurality of motor drivers via the CAN bus comprises:

And the embedded system calculates the displacement required by the movement of the paw according to the terminal physical information of the paw and the motion trail.

And the embedded system sends the control instruction to the motor through a CAN bus.

In one embodiment, the embedded system is an industrial embedded PC with a specific CPU model of Intel Core i 73610 series CPU.

Fig. 4 is a schematic diagram illustrating connection of modules of an assembly robot according to an embodiment of the present invention, where the assembly robot includes:

control transmission protocol transceiving module 401: the teaching aid is used for transmitting and receiving signals between the teaching aid and the embedded system.

The PCIe bus module 402: for transmitting and receiving signals between the sensor and the embedded system.

CAN bus module 403: the motor driver is used for transmitting and receiving signals between the motor driver and the embedded system.

the software module 404: the device is used for receiving the motion trail and the physical information of the tail end of the paw and generating a motor driving signal.

In one embodiment, the PCIe bus module may include:

a position acquisition module: and the three-dimensional displacement measuring instrument is used for receiving the three-dimensional coordinate value of the tail end of the paw sent by the three-dimensional dynamic displacement measuring instrument.

PCI acquisition card module: the hand claw tail end contact force and moment sent by the six-dimensional force sensor are received.

a PCIe transmission module: and the terminal position acquisition module is used for transmitting the terminal physical information of the paw received by the position acquisition module and the PCI acquisition card module to an embedded system.

in one embodiment, the device further comprises a 485 serial port module, which is used for sending an assembly instruction signal to the embedded system by the programmable logic device.

As can be seen from the above description of the embodiments, those skilled in the art can clearly understand that all or part of the steps in the above embodiment methods can be implemented by software plus a general hardware platform. Based on such understanding, the technical solution of the present application may be embodied in the form of a software product, which may be stored in a storage medium, such as a read-only memory (ROM)/RAM, a magnetic disk, an optical disk, or the like, and includes several instructions for enabling a computer device (which may be a personal computer, a server, or a network communication device such as a router) to execute the method according to the embodiments or some parts of the embodiments of the present application.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the apparatus embodiment, since it is substantially similar to the method embodiment, it is relatively simple to describe, and reference may be made to some descriptions of the method embodiment for relevant points. The above-described device and system embodiments are merely illustrative, in which the first user and the second user may or may not be physically separate, and the component that is the initial task template may or may not be a code template. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort. The above description is only an exemplary embodiment of the present application, and is not intended to limit the scope of the present application.

Claims

1. an assembly robot motion control method, characterized in that the method comprises:

2. the method of claim 1, wherein the teach pendant sending a motion trajectory comprises:

the demonstrator receives an action instruction;

3. the method of claim 1, wherein the gripper tip physical information measured by the sensor comprises:

The force and moment obtained by the six-dimensional force sensor.

4. The method of claim 1, wherein the embedded system generating the control command according to the motion trajectory and the physical information of the end of the paw comprises:

5. The method of claim 1, further comprising:

6. the method of claim 1, wherein the embedded system is an industrial-grade embedded PC.

7. an assembly robot motion control apparatus, characterized in that the apparatus comprises:

8. The apparatus of claim 7, wherein the control transmission protocol transceiving module is:

And the Ethernet communication module adopts a Modbus-TCP protocol.

9. the apparatus of claim 7, wherein the PCIe bus module comprises:

10. The apparatus of claim 7, further comprising a 485 serial module for the programmable logic device to send the assembly command signal to the embedded system.