A spray gun for a painting robot and a teaching method

Abstract

This invention relates to the field of spraying technology, specifically disclosing a spraying robot spray gun and its teaching method to solve the problems of high cost, insufficient flexibility, and inadequate accuracy in existing technologies. The invention includes: a gun body, a handle, a high-reflectivity target ball, a servo motor, a three-axis MEMS tilt sensor, a pressure sensor, a controller, and a communication module. The high-reflectivity target ball is installed above the gun body near the nozzle, with its center point rigidly connected to the nozzle. The servo motor is located inside the gun body and connected to the spray gun needle via a connector, driving the needle to move back and forth. This invention uses a spray gun with a high-reflectivity target ball, combined with a single-point fixed 3D LiDAR, and utilizes an industrial robot to achieve static calibration and dynamic calibration, achieving millimeter-level position and pose measurement accuracy. Therefore, it has advantages such as high accuracy, simple deployment, and low cost. During reproduction, the gradual spraying process is precisely synchronized with the movement of the spray gun.

Description

Technical Field

[0001] This invention relates to the field of spraying technology, and in particular to a spraying robot spray gun and teaching method. Background Technology

[0002] In the manufacturing process of clothing such as jeans, spray coating is often required to achieve effects such as spot bleaching. The characteristics of clothing spray coating are: it is usually a localized process; different spray gun positions and varying pressure during the spraying process produce different coating effects, resulting in different patterns and ultimately affecting the aesthetics of the finished garment.

[0003] To address the inefficiency of manual spraying, industrial robots are increasingly being used to replace human labor in garment painting. Currently, spraying robots are commonly deployed using three methods: direct programming, drag-and-drop robot teaching, and handheld spray gun teaching. Direct programming requires repeated debugging of each robot's program to achieve the desired painting effect, demanding high skill levels and being inefficient. Drag-and-drop robot teaching requires specialized robots and controllers, resulting in higher costs and less operational flexibility. In comparison, handheld spray gun teaching eliminates the need for programming and offers greater operational flexibility, although modifications to the spray gun are necessary.

[0004] Currently, researchers have proposed some technical solutions for acquiring pose information of handheld teaching devices, but these solutions are still insufficient for the clothing spraying teaching industry.

[0005] The invention patent with application number 202211387771.1, entitled "Method, System, Device and Medium for Measuring Position Information of Robot Teaching Handle", proposes a method to obtain the position information of the teaching handle by means of the tension value of the connecting rope. Although the method reduces the possibility of tangling or interference of the connecting rope by setting a reference point, it still requires the connecting rope to be tightened during use, which lacks flexibility when used for teaching clothing spraying.

[0006] The invention patent with application number 201910385954.1, "A robot handheld teaching device and method based on stereo vision", provides a solution based on stereo vision. However, the purchase and maintenance costs of vision sensors are high, and it is not suitable for use in dusty scenarios such as spraying.

[0007] The invention patent application number 202010302166.4, entitled "A Robot Teaching Spraying Method and Device for Handheld Tool Teaching," records the pose of the spray gun using an inertial measurement unit (IMU) and then uses a grating line array as an auxiliary sensor to eliminate the accumulated error of the displacement data obtained by IMU integration. This solution requires the installation of a huge grating line array, which is not only costly but also difficult to use and maintain in spraying applications.

[0008] The invention patent application number 202110716031.7, entitled "A Teaching Pendant and Method for Spraying Robots," obtains the spray gun pose during the spraying process by fusing IMU sampling data and UWB sampling data. This solution requires the deployment of multiple base stations and can only achieve centimeter-level positioning accuracy in indoor environments, which cannot meet the requirements for high-precision spraying.

[0009] The invention patent with application number 202210549718.0, entitled "A spray gun based on position sensing technology and its convenient robot programming device", designs a spray gun handle based on three position trackers. Theoretically, it can achieve millimeter-level positioning accuracy. However, it requires two fixed brackets with a spacing of about 3 meters and a height of more than 2 meters to install multiple position receivers for cooperation. Its installation and calibration process is quite cumbersome.

[0010] Furthermore, none of the aforementioned technical solutions consider application scenarios requiring gradual control of paint output. To address this issue, only the invention patent application number 202321691669.0, entitled "A Spray Gun Device," proposes a method that uses a pressure sensor to obtain the pressure applied to the teaching spray gun, and then controls the opening ratio of the air and oil circuit valves to reproduce the effect. While this method can reflect the operator's intention for gradual spraying to some extent, because pressing the spray gun trigger during teaching controls the forward and backward movement of the spray needle, while reproduction uses a different method of controlling the valves, the reproduced clothing spraying effect cannot be completely identical to the teaching effect.

[0011] Therefore, there is a need to provide a spray gun for a painting robot and a teaching method to eliminate the drawbacks of existing technologies. Summary of the Invention

[0012] The purpose of this invention is to provide a spray gun for a painting robot and a teaching method, which solves the problem of inconvenience in the use of existing technologies.

[0013] To achieve the above objectives, the present invention provides the following technical solution:

[0014] A spray gun for a painting robot includes: a gun body, a handle, a high-reflectivity target ball, a servo motor, a three-axis MEMS tilt sensor, a pressure sensor, a controller, and a communication module;

[0015] The high-reflectivity target ball is mounted on the top of the gun body near the muzzle, with its center point rigidly connected to the nozzle of the spray gun; the servo motor is inside the gun body and connected to the spray gun needle via a connector, which can drive the needle to move back and forth; the three-axis MEMS tilt sensor is located at the top of the handle, parallel to the attitude reference plane of the spray gun, and can acquire spray gun attitude data in real time; the pressure sensor is located inside the handle at the trigger press point, and can acquire pressure data when the trigger is pulled in real time; the controller and communication module are installed inside the handle.

[0016] Based on the above technical solutions, the present invention also provides the following optional technical solutions:

[0017] In one alternative: the communication module uses wired or wireless transmission to interact with the outside world.

[0018] In one alternative: the handle is provided with an on / off button for switching the spray gun between three states: off, teach, and reproduce.

[0019] In one alternative: the handle is equipped with an indicator light to display the current status of the spray gun.

[0020] In one alternative approach: when the spray gun is in the teaching state, the controller calculates the needle displacement in real time based on the pressure data obtained by the pressure sensor, sends a signal to the servo motor, adjusts the gap between the needle and the nozzle at the front end of the gun body, and thus controls the amount of paint dispensed. Simultaneously, the controller sends the needle displacement data with timestamps and the spray gun attitude data obtained by the three-axis MEMS tilt sensor through the communication module. When the spray gun is in the reproduction state, the controller receives the needle displacement data in real time through the communication module, sends a signal to the servo motor, adjusts the gap between the needle and the nozzle at the front end of the gun body, and thus controls the amount of paint dispensed.

[0021] A teaching system for a painting robot, using the aforementioned painting robot spray gun, further includes a 3D LiDAR, an industrial control computer, an industrial robot control system, and an industrial robot body; the 3D LiDAR is located above the painting operation area and can scan the high reflectivity target ball above the spray gun body during the teaching process without obstruction; the industrial control computer is connected to the 3D LiDAR to realize 3D LiDAR data acquisition, and is also connected to the industrial robot control system.

[0022] In one alternative: the spray gun installed at the end of the industrial robot body is removed for handheld teaching during the teaching process, and then installed back at the end of the industrial robot body for reproduction.

[0023] In one alternative: during teaching, the industrial control computer interacts with the spray gun via wired or wireless transmission to complete the acquisition of spray gun teaching data, and then generates a spraying program to send to the industrial robot control system; during reproduction, the industrial robot control system runs the program to control the movement of the industrial robot body, and at the same time communicates with the controller of the spray gun to control its servo motor to move synchronously, so as to accurately reproduce the spraying teaching effect.

[0024] A method for teaching a painting robot, comprising teaching the painting robot using the painting robot teaching system, including:

[0025] Step 1: System Calibration

[0026] To calibrate the spray gun of the painting robot, firstly, the three-axis MEMS tilt sensor is calibrated, and then the rigid offset from the center of the spray gun target ball to the nozzle is calibrated.

[0027] The PTP (Precise Time Protocol) is used to synchronize the time of the painting robot teaching system.

[0028] The industrial robot control system calibrates the TCP tool coordinate system of the industrial robot's end-effector spray gun. Obtain the tool coordinate system To the industrial robot flange coordinate system The homogeneous transformation matrix is ​​then used to obtain the tool coordinate system. To the industrial robot base coordinate system The homogeneous transformation matrix;

[0029] Establishing a 3D LiDAR coordinate system To the industrial robot base coordinate system The homogeneous transformation matrix;

[0030] Step Two: Demonstration:

[0031] Teaching the process of removing the spray gun from the industrial robot and holding the spray gun to begin the spraying process;

[0032] The 3D lidar measures the center coordinates of the target sphere in real time and sends the data to the industrial control computer.

[0033] The spray gun controller calculates the needle displacement in real time based on the pressure data obtained by the pressure sensor, sends a signal to the servo motor, adjusts the gap between the needle and the nozzle at the front end of the gun body, and records the needle displacement and attitude angle simultaneously. The needle displacement data with timestamps and the spray gun attitude data obtained by the three-axis MEMS tilt sensor are sent to the industrial control computer through the communication module.

[0034] After teaching is complete, press the on / off button on the handle to switch the spray gun from the teaching state to the off state;

[0035] Step 3: Data Processing;

[0036] The industrial control computer receives the target ball center coordinate data sent by the 3D LiDAR with timestamps, the gun needle displacement data sent by the spray gun controller, and the spray gun attitude data obtained by the three-axis MEMS tilt sensor, and processes the data.

[0037] This includes: aligning the 3D LiDAR, three-axis MEMS tilt sensor, and gun needle displacement data using PTP timestamp differences; converting the target ball center coordinates measured by the 3D LiDAR to the gun muzzle TCP coordinates in the industrial robot base coordinate system; and converting the spray gun attitude data acquired by the three-axis MEMS tilt sensor... , and Transform to the industrial robot base coordinate system;

[0038] Step 4: Generate the program:

[0039] The industrial control computer generates a control program for controlling the industrial robot to perform spraying operations. The program includes industrial robot motion trajectory control instructions and spray gun servo motor control instructions. The industrial control computer sends the control program to the industrial robot control system. The spray gun is reinstalled at the end of the industrial robot, and the program can be run to achieve synchronous and precise control of the spray gun posture and the gradual pressing pressure of the spray gun.

[0040] In one alternative: the calibration of the triaxial MEMS tilt sensor includes static calibration and dynamic calibration.

[0041] In one alternative approach: the calibration of the rigid offset from the center of the spray gun target ball to the nozzle includes: mounting the spray gun to the end effector of an industrial robot, controlling the spray gun via the industrial robot, and ensuring that the spray gun target ball is within the field of view of the 3D LiDAR, causing the nozzle TCP to touch a fixed point through six different postures; the 3D LiDAR acquiring the coordinates of the target ball center in each posture; constructing a minimum objective function to obtain the spray gun nozzle tool coordinate system. To 3D LiDAR coordinate system Homogeneous transformation matrix Then, the rigid offset from the center of the spray gun target ball to the muzzle is calculated.

[0042] In one alternative approach, time synchronization is achieved using the PTP precision time protocol, which includes: based on the IEEE 1588 protocol, the industrial control computer acts as the master clock and periodically sends Sync Messages, while the spray gun controller, 3D LiDAR, and industrial robot control system act as slave clocks, receiving and recording timestamps, and calculating time offsets to adjust their local clocks.

[0043] In one alternative: the TCP tool coordinate system of the calibration industrial robot end effector spray gun. This includes: using the four-point method to obtain the homogeneous transformation matrix from the TCP tool coordinate system at the spray gun nozzle to the flange coordinate system. Then the tool coordinate system can be obtained. To the industrial robot base coordinate system homogeneous transformation matrix .

[0044] In one alternative approach: establish a 3D lidar coordinate system. To the industrial robot base coordinate system homogeneous transformation matrix Directly from the formula get.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] 1. This invention uses a spray gun with a high reflectivity target ball, combined with a single-point fixed 3D laser radar, and uses an industrial robot to achieve static calibration and dynamic calibration. The position and pose measurement accuracy reaches the millimeter level. Therefore, it has the advantages of high precision, simple deployment and low cost. The gradual spraying process is precisely synchronized with the movement of the spray gun during reproduction.

[0047] 2. The spray gun of the present invention replaces the mechanical structure of changing the position of the gun needle by trigger pull with a pressure sensor to collect the trigger pull pressure value, then calculate the gun needle displacement, and then control the movement of the gun needle by a servo motor. This makes the adjustment of the amount of paint dispensed by the spray gun completely the same in teaching and reproduction, ensuring the consistency of the spraying effect. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the spray gun structure of the present invention.

[0049] Figure 2 This is a schematic diagram of the spraying robot structure of the present invention.

[0050] Figure 3 This is a teaching logic block diagram of the present invention.

[0051] Figure label annotations:

[0052] 1-Gun body; 2-Handle; 3-High reflectivity target ball; 4-Servo motor; 5-Controller; 6-Connector; 7-Gun needle;

[0053] 8-Pressure sensor; 9-Triaxial tilt sensor; 10-Communication module; 11-Handle trigger; 12-Button; 13-Indicator light;

[0054] 01-Spray gun; 02-3D LiDAR; 03-Industrial control computer; 04-Industrial robot control system; 05-Industrial robot body. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] Step 1: Initialization and Calibration

[0057] The calibration and standardization of the three-axis MEMS tilt sensor are as follows:

[0058] Install the spray gun onto the end effector of the industrial robot and define the TCP tool coordinate system for the spray gun nozzle. The coordinate axis direction is related to the industrial robot flange coordinate system. Once consistent, adjust the industrial robot to the zero position:

[0059] Static calibration:

[0060] At this time, the acquired triaxial MEMS tilt sensor measurement value is the installation error, including: roll angle. Pitch angle and heading angle ;

[0061] Calibration requires eliminating installation errors. , and Input to the spray gun controller; the calibrated sensor output value is: , , .

[0062] Dynamic calibration:

[0063] By using the multi-pose motion of an industrial robot, the rotational relationship between the coordinate system of a three-axis MEMS tilt sensor and the flange coordinate system is calibrated.

[0064] Controlling industrial robots to move in different postures, covering Roll angle, Pitch angle and Heading angle, synchronously recording the output of the three-axis MEMS tilt sensor at each attitude. , and The actual flange posture calculated by the industrial robot using the forward kinematics formula .

[0065] Minimize the residual between the sensor output and the actual flange orientation:

[0066]

[0067] Then, the rotation matrix from the triaxial MEMS tilt sensor coordinate system to the flange coordinate system is calculated based on this. .

[0068] Rigid offset from the center of the calibrated target ball to the muzzle Specifically:

[0069] The spray gun is installed at the end of an industrial robot, and the industrial robot controls the spray gun. Under the premise of ensuring that the spray gun target ball is within the field of view of the 3D LiDAR, the spray gun nozzle TCP touches a fixed point in 6 different postures.

[0070] 3D LiDAR acquires the center coordinates of the target ball in each posture. ;

[0071] Construct the minimum objective function:

[0072]

[0073] in, Spray gun muzzle tool coordinate system To 3D LiDAR coordinate system Homogeneous transformation matrix The rotation matrix; Spray gun muzzle tool coordinate system To 3D LiDAR coordinate system Homogeneous transformation matrix Translation vector;

[0074] Solve and Then we can obtain:

[0075]

[0076] The PTP (Precision Time Protocol) is used to synchronize the time of the painting robot teaching system, including:

[0077] Based on the IEEE 1588 protocol, the industrial control computer acts as the master clock, periodically sending Sync Messages. The spray gun controller, 3D LiDAR, and industrial robot control system act as slave clocks, receiving and recording timestamps. The time offset is:

[0078]

[0079] in, This is for transmission delay.

[0080] Then, the spray gun controller, 3D LiDAR, and industrial robot control system adjust their local clocks according to the calculated time offset. The adjusted clock time is:

[0081]

[0082] in, This is the local time before adjustment.

[0083] Calibration of the TCP tool coordinate system of the end-effector spray gun in the teaching system for spraying robots Specifically, this includes: using a four-point method, the robot controls the spray gun, causing the spray gun nozzle TCP to touch a fixed point through four different postures; and recording the flange coordinate system pose under different postures. Solving the homogeneous transformation matrix using the least squares method Then the tool coordinate system can be obtained. To the industrial robot base coordinate system Homogeneous transformation matrix:

[0084]

[0085] in, This is the homogeneous transformation matrix from the flange coordinate system to the base coordinate system of the industrial robot.

[0086] (5) Establish a 3D lidar coordinate system To the industrial robot base coordinate system homogeneous transformation matrix It can be obtained directly from the formula: ,in Spray gun muzzle tool coordinate system To 3D LiDAR coordinate system The homogeneous transformation matrix.

[0087] Step Two: Demonstration:

[0088] Remove the spray gun from the industrial robot, hold the spray gun, press the on / off button on the handle to put the spray gun into the teaching state, and start the teaching of the spraying process.

[0089] 3D LiDAR measures the center coordinates of the target sphere in real time. Send to the industrial control computer;

[0090] The spray gun controller calculates the needle displacement in real time based on the pressure data obtained from the pressure sensor. It sends a signal to the servo motor to adjust the gap between the gun needle and the nozzle at the front end of the gun body, and simultaneously records the displacement of the gun needle. and attitude angle , and The time-stamped gun needle displacement data and the spray gun attitude data acquired by the three-axis MEMS tilt sensor are sent to the industrial control computer through the communication module.

[0091] After teaching is complete, press the on / off button on the handle to switch the spray gun from teaching mode to off mode.

[0092] Step 3: Data Processing

[0093] The industrial control computer receives the center coordinates of the target sphere from a 3D LiDAR with a timestamp. The needle displacement data sent by the spray gun's controller Spray gun attitude data acquired by a three-axis MEMS tilt sensor , and To perform data processing:

[0094] Align the data from 3D LiDAR, triaxial MEMS tilt sensor, and needle displacement according to the PTP timestamp difference to compensate for the sampling rate differences of different sensors;

[0095] The coordinates of the target sphere's center measured by 3D lidar Convert to muzzle TCP coordinates in the industrial robot base coordinate system:

[0096]

[0097] (4) The spray gun attitude data acquired by the three-axis MEMS tilt sensor , and Switch to the industrial robot base coordinate system.

[0098] First, the sensor data is represented as a rotation matrix. form:

[0099]

[0100] in:

[0101]

[0102]

[0103]

[0104] Then the muzzle TCP orientation in the industrial robot's base coordinate system is obtained as follows:

[0105]

[0106] Step 4: Generate the program:

[0107] The industrial control computer generates a control program for controlling the industrial robot to perform spraying operations, and sends it to the industrial robot control system. Once the spray gun is reinstalled at the end of the industrial robot, the program can be run to reproduce the operation.

[0108] The program includes industrial robot motion trajectory control instructions and spray gun servo motor control instructions to achieve synchronous and precise control of spray gun posture and spray gun gradual pressing pressure.

[0109] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A teaching method for a painting robot, Its characteristics include: Step 1: System Calibration The spray gun of the spraying robot is calibrated. First, the three-axis MEMS tilt sensor (9) is calibrated, and then the rigid offset from the center of the spray gun target ball to the nozzle is calibrated. The PTP precise time protocol is used to synchronize the time of the teaching system for the painting robot. Calibration of the TCP tool coordinate system for the end effector spray gun of an industrial robot control system Obtain the tool coordinate system To the industrial robot flange coordinate system The homogeneous transformation matrix is ​​then used to obtain the tool coordinate system. To the industrial robot base coordinate system The homogeneous transformation matrix; Establishing a 3D LiDAR coordinate system To the industrial robot base coordinate system The homogeneous transformation matrix; Step Two: Demonstration: Teaching the process of removing the spray gun from the industrial robot and holding the spray gun to begin the spraying process; The 3D lidar measures the center coordinates of the target sphere in real time and sends the data to the industrial control computer. The spray gun controller (5) calculates the needle displacement in real time based on the pressure data obtained by the pressure sensor (8), sends a signal to the servo motor, adjusts the gap between the needle and the nozzle at the front end of the gun body (1), and records the needle displacement and attitude angle simultaneously. The needle displacement data with timestamp and the spray gun attitude data obtained by the three-axis MEMS tilt sensor (9) are sent to the industrial control computer through the communication module (10). After teaching is complete, press the on / off button on the handle (2) to switch the spray gun from the teaching state to the off state; Step 3: Data Processing The industrial control computer receives the target ball center coordinate data sent by the 3D laser radar with timestamp, the gun needle displacement data sent by the spray gun controller (5), and the spray gun attitude data obtained by the three-axis MEMS tilt sensor (9), and performs data processing. This includes: aligning the displacement data of the 3D LiDAR, the three-axis MEMS tilt sensor (9), and the gun needle according to the PTP timestamp difference; converting the target ball center coordinates measured by the 3D LiDAR into the gun muzzle TCP coordinates in the industrial robot base coordinate system; and converting the spray gun attitude data acquired by the three-axis MEMS tilt sensor (9) into the target ball center coordinates measured by the 3D LiDAR. , and Transform to the industrial robot base coordinate system; Step 4: Generate the program: The industrial control computer generates a control program for controlling the industrial robot to perform spraying operations. The program includes industrial robot motion trajectory control instructions and spray gun servo motor control instructions. The industrial control computer sends the control program to the industrial robot control system. The spray gun is reinstalled at the end of the industrial robot, and the program can be run to achieve synchronous and precise control of the spray gun posture and the gradual pressing pressure of the spray gun. The spray gun for the painting robot includes: gun body (1), handle (2), high reflectivity target ball (3), servo motor (4), three-axis MEMS tilt sensor (9), pressure sensor (8), controller (5) and communication module (10). The high reflectivity target ball (3) is installed above the gun body (1) near the muzzle, and its center point is rigidly connected to the nozzle of the spray gun; the servo motor (4) is inside the gun body (1) and is connected to the nozzle needle of the spray gun (01) through a connector, which can drive the nozzle needle to move back and forth; the three-axis MEMS tilt sensor (9) is located at the upper end of the handle (2) and is parallel to the attitude reference plane of the spray gun (01), which can acquire the attitude data of the spray gun (01) in real time; the pressure sensor (8) is located inside the handle (2) at the trigger press point, which can acquire the pressure data when the trigger is pulled in real time; the controller (5) and the communication module (10) are installed inside the handle (2); When the spray gun (01) is in the teaching state, the controller (5) calculates the needle displacement in real time based on the pressure data obtained by the pressure sensor (8), sends a signal to the servo motor (4), adjusts the gap between the needle and the nozzle at the front end of the gun body (1), and controls the amount of paint dispensed. At the same time, the needle displacement data with timestamp and the spray gun attitude data obtained by the three-axis MEMS tilt sensor (9) are sent out through the communication module (10). When the spray gun (01) is in the reproduction state, the controller (5) receives the needle displacement data in real time through the communication module (10), sends a signal to the servo motor (4), adjusts the gap between the needle and the nozzle at the front end of the gun body (1), and controls the amount of paint dispensed.

2. The teaching method for a painting robot according to claim 1, characterized in that, The calibration of the triaxial MEMS tilt sensor (9) includes static calibration and dynamic calibration.

3. The teaching method for a painting robot according to claim 1, characterized in that, The calibration of the rigid offset from the center of the spray gun target ball to the nozzle includes: mounting the spray gun to the end effector of an industrial robot, controlling the spray gun through the industrial robot, and ensuring that the spray gun target ball is within the field of view of the 3D LiDAR, causing the nozzle TCP to touch a fixed point through six different postures; the 3D LiDAR acquiring the coordinates of the target ball center in each posture; constructing a minimum objective function to obtain the spray gun nozzle tool coordinate system. To 3D LiDAR coordinate system Homogeneous transformation matrix Then, the rigid offset from the center of the spray gun target ball to the muzzle is calculated.

4. The teaching method for a painting robot according to claim 1, characterized in that, Time synchronization is achieved using the PTP precision time protocol, which includes: based on the IEEE1588 protocol, the industrial control computer is used as the master clock to send Sync Messages periodically, and the spray gun controller (5), 3D laser radar, and industrial robot control system are used as slave clocks to receive and record timestamps, calculate time offsets and adjust their own local clocks.

5. The teaching method for a painting robot according to claim 1, characterized in that, The TCP tool coordinate system of the calibration industrial robot end-effector spray gun This includes: using the four-point method to obtain the homogeneous transformation matrix from the TCP tool coordinate system at the spray gun nozzle to the flange coordinate system. Then the tool coordinate system can be obtained. To the industrial robot base coordinate system homogeneous transformation matrix .

6. The teaching method for a painting robot according to claim 2, characterized in that, The establishment of the 3D LiDAR coordinate system To the industrial robot base coordinate system homogeneous transformation matrix Directly from the formula get.

7. A teaching system for a painting robot to implement the teaching method of claim 1, wherein the painting robot spray gun is characterized in that, It also includes a 3D laser radar, an industrial control computer, an industrial robot control system, and an industrial robot body; the 3D laser radar is located above the spraying operation area and can scan the high reflectivity target ball (3) above the spray gun (01) during the teaching process without obstruction; the industrial control computer is connected to the 3D laser radar to realize 3D laser radar data acquisition, and is also connected to the industrial robot control system. During teaching, the industrial control computer uses wired and wireless transmission to interact with the spray gun, completes the spray gun teaching data acquisition, and then generates a spraying program to send to the industrial robot control system. During reproduction, the industrial robot control system runs the program, controls the movement of the industrial robot body, and communicates with the spray gun controller (5) to control its servo motor (4) to move synchronously, so as to accurately reproduce the spraying teaching effect.

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