Welding robot control method and system for preventing collision

Abstract

The invention relates to the technical field of control systems, in particular to an anti-collision welding robot control method and system, and the method comprises the steps: obtaining thermal infrared temperature data and ultrasonic echo data of a to-be-machined workpiece in a welding track; based on the thermal infrared temperature data, the machining state of the to-be-machined workpiece is determined; compensating the ultrasonic echo data to obtain ultrasonic echo compensation data; determining the dynamic frequency domain offset distortion degree of the ultrasonic echo compensation data; and feedback adjustment is conducted on the moving speed of the welding robot and the welding speed of the welding track. Through cooperation of the low-power-consumption ultrasonic sensor and the infrared temperature sensor, anti-collision control can still be accurately completed in real time under the condition that hardware is limited, and energy consumption is remarkably reduced; and on the other hand, ultrasonic echo distortion caused by high temperature and a complex workpiece surface is effectively eliminated by utilizing temperature compensation and structural complexity identification, and the accuracy and reliability of distance detection are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of control systems, in particular to a welding robot control method and system for collision prevention. BACKGROUND

[0002] A collision-preventing welding robot is a robot with self-protection function, mainly used for performing welding work. When performing welding work, it can monitor and avoid collision with surrounding obstacles or other mechanical parts in real time, so as to ensure the smooth progress of the welding process and avoid equipment damage, personnel injury or production interruption. Such robots are usually applied in automated production lines or dangerous environments, which can improve production efficiency and ensure work safety. In order to realize the collision prevention function and considering the actual hardware limitation problem, the welding robot is usually equipped with low-energy monitoring sensors, which mainly include: (1) ultrasonic sensor, which uses the reflection of sound waves to detect the distance between the robot and the surrounding objects. Ultrasonic sensors are commonly used for short-range obstacle detection and can provide real-time collision warning. (2) Infrared sensor, which detects the reflection or obstruction of infrared light by objects to help the robot determine the workpiece temperature value in the surrounding environment and assist in controlling the collision prevention system of the welding robot.

[0003] Existing problems: In the actual collision-preventing welding process, the shape and posture of multi-target workpieces have certain complexity, and the shape and posture of the workpieces will affect the echo characteristics of the ultrasonic sensor, thereby causing the generation of blind areas or making the echo produce multiple-reflection complex echo characteristics. In addition, the high temperature of the workpiece during welding will cause the change of the reflection characteristics of the workpiece surface, thereby reducing the ultrasonic echo energy. In summary, in the actual collision-preventing welding process, the shape and posture of the workpiece and the high temperature during welding will affect the precision and real-time performance of the collision-preventing control of the welding robot. SUMMARY

[0004] The present application provides a welding robot control method and system for collision prevention to solve the existing problems.

[0005] The welding robot control method and system for collision prevention of the present application adopt the following technical solutions: One embodiment of the present application provides a welding robot control method for collision prevention, the method comprising: acquiring thermal infrared temperature data and ultrasonic echo data of a workpiece in a welding track; wherein the thermal infrared temperature data and the ultrasonic echo data are collected by an infrared sensor and an ultrasonic sensor respectively deployed on a welding robot; determining a processing state of the workpiece based on the thermal infrared temperature data; compensating the ultrasonic echo data based on the processing state to obtain ultrasonic echo compensation data; determining a frequency domain offset distortion degree of the ultrasonic echo compensation data; wherein the frequency domain offset distortion degree is used to represent the frequency energy distribution distortion intensity of the ultrasonic echo compensation data; and feeding back and adjusting the moving speed of the welding robot and the welding speed of the welding track based on the frequency domain offset distortion degree.

[0006] Further, the method further comprises: acquiring a thermal infrared judgment set; wherein the thermal infrared judgment set comprises the thermal infrared temperature data collected by the infrared sensor in a preset period; calculating the average value of all the thermal infrared temperature data in the current thermal infrared judgment set to obtain a first temperature average value; acquiring a preset number of historical thermal infrared judgment sets, calculating the average value of all the thermal infrared temperature data in each of the historical thermal infrared judgment sets to obtain a second temperature average value; calculating the sum of the differences between the first temperature average value and each of the second temperature average values to obtain a temperature increment sum; and determining a processing state coefficient of the workpiece based on the temperature increment sum and the first temperature average value; wherein the processing state coefficient is used to represent the influence degree of the temperature of the workpiece itself on the ultrasonic echo data.

[0007] Further, the method further comprises: performing normalization processing on the processing state coefficient; if the processing state coefficient after normalization processing is within a preset state coefficient range, determining that the ultrasonic echo data needs to be compensated for temperature, and compensating the ultrasonic echo data based on the processing state coefficient after normalization processing to obtain ultrasonic echo compensation data.

[0008] Further, the method further comprises: determining an ultrasonic echo compensation coefficient based on the processing state coefficient and a compensation parameter; wherein the compensation parameter is used to represent the ultrasonic echo data compensation proportion caused by unit processing state coefficient change; and compensating the ultrasonic echo data based on the ultrasonic echo compensation coefficient to obtain ultrasonic echo compensation data.

[0009] Further, the determining the frequency domain offset distortion degree of the ultrasonic echo compensation data comprises: obtaining an ultrasonic echo judgment set; the ultrasonic echo judgment set comprises the ultrasonic echo compensation data of the ultrasonic echo data collected by the ultrasonic sensor in a preset period; the ultrasonic echo judgment set comprises a current ultrasonic echo judgment set and a preset number of historical ultrasonic echo judgment sets; determining a time domain overlap amount of the current ultrasonic echo judgment set based on the ultrasonic echo compensation data in the ultrasonic echo judgment set; the time domain overlap amount is used to represent a multipath superposition degree of the ultrasonic echo compensation data; determining a workpiece structure complexity index based on the time domain overlap amount; and determining the frequency domain offset distortion degree of the current ultrasonic echo judgment set based on the workpiece structure complexity index.

[0010] Further, the determining the time domain overlap amount of the current ultrasonic echo judgment set based on the ultrasonic echo compensation data in the ultrasonic echo judgment set comprises: fitting the ultrasonic echo compensation data in the ultrasonic echo judgment set into a continuous curve; obtaining a maximum point and an ultrasonic amplitude corresponding to the maximum point in the curve; obtaining a pair of adjacent maximum points; the pair of adjacent maximum points comprises two adjacent maximum points in the maximum points; calculating a sum of point sequence number difference values of the maximum points in all the pairs of adjacent maximum points; the point sequence number is a sequence number of the maximum point in the corresponding ultrasonic echo judgment set; calculating a difference absolute value between a mean value of all the maximum points and a mean value of the ultrasonic echo compensation data in the current ultrasonic echo judgment set; and determining the time domain overlap amount of the current ultrasonic echo judgment set based on the sum of the point sequence number difference values and the difference absolute value.

[0011] Further, the determining the workpiece structure complexity index based on the time domain overlap amount comprises: performing normalization processing on the time domain overlap amount to determine the workpiece structure complexity index.

[0012] Further, the determining the frequency domain offset distortion degree of the current ultrasonic echo judgment set based on the workpiece structure complexity index comprises: obtaining a first energy of the ultrasonic echo compensation data in a first frequency region and a second energy of the ultrasonic echo compensation data in a second frequency region in the current ultrasonic echo judgment set; the frequency of the second frequency region is greater than the frequency of the first frequency region; calculating an energy difference absolute value of the first energy and the second energy; and determining the frequency domain offset distortion degree of the current ultrasonic echo judgment set based on the workpiece structure complexity index and the energy difference absolute value.

[0013] Further, the feedback adjusting the moving speed of the welding robot and the welding speed of the welding track based on the frequency domain offset distortion degree comprises: The frequency domain offset distortion degree is normalized, and if the normalized frequency domain offset distortion degree is greater than a preset alarm threshold, a collision avoidance alarm is performed. And, the absolute value of the difference between the frequency domain offset distortion degree corresponding to the current ultrasonic echo determination set and the frequency domain offset distortion degree corresponding to the previous ultrasonic echo determination set is calculated, and if the ratio of the absolute value of the difference to the frequency domain offset distortion degree corresponding to the current ultrasonic echo determination set is greater than a preset speed adjustment threshold, the moving speed of the welding robot and the welding speed of the welding track are feedback adjusted to reduce the moving speed of the welding robot and the welding speed of the welding track.

[0014] An embodiment of the present application provides a welding robot control system for collision avoidance, comprising: a host computer and infrared sensors and ultrasonic sensors electrically connected with the host computer, the infrared sensors and the ultrasonic sensors are installed on a welding robot, wherein: The infrared sensors are used for collecting thermal infrared temperature data of workpieces in a welding track and sending the thermal infrared temperature data to the host computer. The ultrasonic sensors are used for collecting ultrasonic echo data of workpieces in a welding track and sending the ultrasonic echo data to the host computer. The host computer is used for acquiring the thermal infrared temperature data and the ultrasonic echo data, determining the processing state of the workpieces based on the thermal infrared temperature data, compensating the ultrasonic echo data based on the processing state to acquire ultrasonic echo compensation data, determining the frequency domain offset distortion degree of the ultrasonic echo compensation data, wherein the frequency domain offset distortion degree is used for representing the frequency energy distribution distortion intensity of the ultrasonic echo compensation data, and feedback adjusting the moving speed of the welding robot and the welding speed of the welding track based on the frequency domain offset distortion degree.

[0015] The technical scheme of the present application has the following beneficial effects: In the embodiment of the present application, the thermal infrared temperature data and ultrasonic echo data of the workpiece to be processed in the welding track are acquired; the processing state of the workpiece to be processed is determined based on the thermal infrared temperature data; the ultrasonic echo compensation data is acquired by compensating the ultrasonic echo data based on the processing state; the dynamic frequency domain offset distortion degree of the ultrasonic echo compensation data is determined; and the moving speed of the welding robot and the welding speed of the welding track are feedback adjusted based on the dynamic frequency domain offset distortion degree. Thus, the present application can still complete the anti-collision control in real time and accurately under the condition of limited hardware by the cooperation of the low-power ultrasonic sensor and the infrared temperature sensor, and the system energy consumption is significantly reduced. On the other hand, the ultrasonic echo distortion caused by high temperature and complex workpiece surface is effectively eliminated by using temperature compensation and structural complexity identification, and the accuracy and reliability of distance detection are improved. On the other hand, the closed-loop feedback mechanism based on the dynamic frequency domain offset amount enables the robot to automatically slow down or stop in milliseconds, avoiding equipment damage and personnel injury. On the other hand, the welding robot control method for anti-collision described above does not require additional high-cost sensors and can be deployed only by software algorithm upgrade, and has good universality and economic promotion value. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0017] Figure 1 The flowchart of the welding robot control method for anti-collision provided by the embodiment of the present application is shown. Figure 2 The structural diagram of the welding robot control system for anti-collision provided by the embodiment of the present application is shown. DETAILED DESCRIPTION

[0018] In order to further explain the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the following will combine the drawings and the preferred embodiments to specifically describe the specific implementation, structure, features and effects of the welding robot control method and system for anti-collision according to the present application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0020] The application provides a welding robot control method and system for collision prevention.

[0021] Please refer to Figure 1 which shows a welding robot control method for collision prevention, comprising: Step S110: acquiring thermal infrared temperature data and ultrasonic echo data of a workpiece in a welding track; wherein the thermal infrared temperature data and the ultrasonic echo data are collected by an infrared sensor and an ultrasonic sensor respectively deployed on the welding robot.

[0022] It should be noted that the welding track is a path trajectory that the welding robot torch (or welding tongs) needs to accurately pass through in the surface or the surrounding area of the workpiece, and is a physical execution route of the welding operation. Common forms include straight track, curved track and spot welding track, etc. The welding robot can automatically weld according to the preset welding track. The accuracy of the track directly affects the weld quality and the workpiece assembly accuracy. During the welding process, the welding robot can monitor the workpiece state on the welding track in real time through sensors (such as ultrasonic sensors, infrared sensors, etc.), so as to dynamically adjust the welding parameters and speed. If there is an unexpected obstacle or workpiece deviation on the track, the welding robot will trigger the collision prevention mechanism.

[0023] It should be further noted that the ultrasonic sensor can measure the distance by emitting ultrasonic signals and receiving the reflected signals, and the infrared sensor can measure the temperature by the principle of object emitting infrared radiation. The data type of the distance information returned by the ultrasonic sensor and the temperature information obtained by the infrared sensor can both be float32 type. In addition, a time stamp can be attached after each sensor sampling, and the time stamp is usually transmitted in int64 format, indicating the time of sampling.

[0024] Step S120: determining the processing state of the workpiece based on the thermal infrared temperature data.

[0025] It is required to be explained: the ultrasonic echo signal of the ultrasonic sensor is used to determine whether there is a possibility of collision on the moving track of the welding robot and the welding track. The common obstacle is the workpiece to be processed or the workpiece that has been in the processing state. Since the ultrasonic sensor receives the reflection result of the ultrasonic emission to the surface of the object and analyzes and identifies the reflection result to determine the structure characteristics of the object itself and the distance relationship with the current emission target. The closer the distance between the obstacle and the moving target, the shorter the time of the reflected echo, and the higher the echo intensity. However, when the workpiece shows temperature abnormity, that is, the infrared sensor parameter is high, the temperature of the workpiece will affect the characteristics of the workpiece to the echo signal, which is specifically shown as follows: the propagation speed of the ultrasonic wave is affected by the temperature of the medium (which can be the metal workpiece to be processed in the embodiment of the present application). When the metal is heated, its density and elastic modulus change, thereby changing the propagation speed of the ultrasonic wave. In particular: at high temperature, the metal surface can become more irregular, causing the intensity of the reflected echo to weaken, and at the same time, the metal surface can be oxidized or other substances can be formed, further absorbing or scattering the ultrasonic wave. Therefore, in order to avoid the indirect echo noise caused by temperature change when determining the structure complexity of the workpiece by the ultrasonic echo, before analyzing the structure complexity and adjusting the welding robot moving speed and the welding speed according to the structure complexity, the workpiece processing state can be identified and the ultrasonic echo data can be temperature compensated based on the workpiece processing state. The specific scheme is as follows: Preferably, in an embodiment of the present application, the above step S120 can include: obtaining a thermal infrared determination set; wherein the thermal infrared determination set includes thermal infrared temperature data collected by the infrared sensor in a preset period; calculating the average value of all thermal infrared temperature data in the current thermal infrared determination set to obtain a first temperature average value; obtaining a preset number of historical thermal infrared determination sets, calculating the average value of all thermal infrared temperature data in each historical thermal infrared determination set to obtain a second temperature average value; calculating the sum of the differences between the first temperature average value and each second temperature average value to obtain a temperature increment sum; determining the processing state coefficient of the workpiece based on the temperature increment sum and the first temperature average value; wherein the processing state coefficient is used to represent the influence degree of the temperature of the workpiece on the ultrasonic echo data. For example: The real-time parameter value of the infrared sensor, that is, the thermal infrared temperature value, refers to the temperature value of the object in the detection angle range of the sensor, and the unit is ℃. The sampling frequency of the infrared sensor and the sampling frequency of the ultrasonic sensor can be set to the same frequency, for example: both are 20 times per second. The sequence of the thermal infrared temperature data can be: , wherein, represents the first thermal infrared temperature data in the sequence, The thermal infrared temperature value collected by the near-infrared sensor. The thermal infrared temperature data value collected every second is taken as a thermal infrared determination set, that is, every 20 thermal infrared data is taken as a determination set, and one determination set corresponds to one workpiece state. That is, for the infrared sensor of the welding robot, the real-time state of the workpiece in the welding track is updated every second.

[0026] If the average temperature in the current thermal infrared determination set (wherein, indicates the serial number of the determination set) is high, stable and continuous, and shows an increasing trend over time, it is determined that the workpiece is in a processing state. Among them, for the part showing an increasing trend, its physical meaning is that for the welding robot in this state, if the moving direction is towards the processing workpiece, then as the distance approaches, the processing workpiece object has a higher thermal radiation effect, and the corresponding temperature is higher. And when the workpiece is soldered by soldering, the temperature at the welding position is continuously rising before the welding is completed, which also shows an increasing trend.

[0027] In summary, while obtaining the thermal infrared temperature mean value in the current determination set, the thermal infrared temperature mean values in the previous determination sets can also be obtained , so as to calculate the processing state coefficient:

[0028] Among them, indicates the processing state coefficient corresponding to the th determination set; indicates the temperature mean value of the previous determination sets.

[0029] Among them, As a coefficient, the higher the average temperature in the determination set, the higher the corresponding processing state coefficient, and the more likely it is to affect the state of the ultrasonic echo; the purpose of in the formula is to quantify the increasing nature in different determination sets. The higher the sum of the difference, the more obvious the increasing effect of the temperature, at this time, the welding robot moves towards the processing workpiece on the predetermined track, or the processing workpiece causes the local thermal infrared temperature to rise due to continuous welding.

[0030] Step S130: Based on the processing state, the ultrasonic echo data is compensated to obtain ultrasonic echo compensation data.

[0031] Preferably, in one embodiment of the present application, the step S130 can include: normalizing the processing state coefficient; if the normalized processing state coefficient is within a preset state coefficient range, determining that the ultrasonic echo data needs to be compensated for temperature, and compensating for the ultrasonic echo data based on the normalized processing state coefficient to obtain ultrasonic echo compensation data. For example, the processing state coefficient value of the workpiece is normalized, and when the processing state coefficient is within a range of 0.5 to 1.5, it is considered that the ultrasonic echo needs to be compensated for temperature due to the temperature of the workpiece itself. Otherwise, the ultrasonic echo data is normally analyzed to obtain real-time distance.

[0032] It should be noted that the method for determining distance based on ultrasonic echo data is a relatively mature known technology, and its specific implementation mode can be referred to related technologies, and the embodiment of the present application will not be described again.

[0033] Preferably, in one embodiment of the present application, the above compensation for the ultrasonic echo data based on the normalized processing state coefficient to obtain ultrasonic echo compensation data includes: determining an ultrasonic echo compensation coefficient based on the processing state coefficient and a compensation parameter, wherein the compensation parameter is used to represent the proportion of ultrasonic echo data compensation caused by a unit change of the processing state coefficient; and compensating for the ultrasonic echo data based on the ultrasonic echo compensation coefficient to obtain ultrasonic echo compensation data. For example: The ultrasonic echo compensation coefficient is in a positive correlation with the processing state coefficient, that is, the higher the processing state coefficient, the higher the corresponding ultrasonic echo compensation coefficient. Specifically, all ultrasonic echo amplitudes in a determination set (also referred to as a current determination set) that needs to be compensated for temperature are compensated for, and the ultrasonic echo data in the determination set is set as:

[0034] 20 echo amplitude data (echo data is discrete) in one ultrasonic echo determination set.

[0035] The compensated ultrasonic echo compensation data is:

[0036] represents the i-th ultrasonic echo compensation data in the j-th determination set; and ​​​​​​To compensate the parameter, the parameter is an empirical value for representing the compensation proportion of the ultrasonic echo data caused by the unit processing state coefficient change; it can be understood that due to the inconsistent characteristics of each ultrasonic sensor, the compensation parameter can be factory-referenced.

[0037] Step S140: determining the frequency domain offset distortion degree of the ultrasonic echo compensation data; wherein the frequency domain offset distortion degree is used to represent the frequency domain energy distribution distortion intensity of the ultrasonic echo compensation data.

[0038] It is necessary to explain that after the ultrasonic echo data is compensated, the ultrasonic echo amplitude eliminates the problem of poor feedback control caused by temperature influence. At this time, the corresponding workpiece structure state can be further analyzed. Specifically: in the welding robot analysis control process, the environmental factors affecting the accuracy of the ultrasonic sensor echo data are the actual processing state of the workpiece, that is, the temperature value and the corresponding workpiece structure state in the above scheme. The influence principle of the structure state is analyzed as follows: first, the smoothness or irregularity of the workpiece surface will directly affect the reflection intensity of the ultrasonic wave. When the ultrasonic wave hits the smooth metal surface, the reflection intensity is high, which can form a strong echo peak. Secondly, the geometry of the workpiece (such as unevenness or angle change) will cause the ultrasonic wave to reflect in different directions and angles. For example, when the ultrasonic wave enters the edge or protruding area of the workpiece, multiple reflections will occur, causing the peak values of the echo signal to be irregularly superimposed in time. Finally, during the welding process, especially in the case of complex workpiece surface shape, the ultrasonic wave will be reflected multiple times inside the workpiece, producing multiple echo signals. Such echo signals are superimposed on each other, forming multiple signal peaks, which makes the originally single echo signal more complex. Therefore, after analysis, the higher the peak value of the ultrasonic echo in the time domain (after fitting the amplitude points of the ultrasonic echo into a continuous curve), and the more obvious the peak value superposition, the higher the complexity of the structure of the corresponding processing workpiece, and the greater the influence on the welding robot for distance feedback judgment through the ultrasonic echo. The specific scheme is as follows: Preferably, in an embodiment of the present application, the above step S140 can include: obtaining an ultrasonic echo judgment set; wherein the ultrasonic echo judgment set includes the ultrasonic echo compensation data of the ultrasonic echo data collected by the ultrasonic sensor in a preset period; the ultrasonic echo judgment set includes the current ultrasonic echo judgment set and a preset number of historical ultrasonic echo judgment sets; based on the ultrasonic echo compensation data in the ultrasonic echo judgment set, determining the time domain overlap amount of the current ultrasonic echo judgment set; wherein the time domain overlap amount is used to represent the multipath superposition degree of the ultrasonic echo compensation data; based on the time domain overlap amount, determining the workpiece structure complexity index; based on the workpiece structure complexity index, determining the frequency domain offset distortion degree of the current ultrasonic echo judgment set.

[0039] Preferably, in one embodiment of the present application, the above determining the time domain overlap amount of the current ultrasonic echo judgment set based on the ultrasonic echo compensation data in the ultrasonic echo judgment set comprises: fitting the ultrasonic echo compensation data in the ultrasonic echo judgment set into a continuous curve; obtaining a maximum point and its corresponding ultrasonic amplitude in the curve; obtaining a pair of adjacent maximum points, wherein the pair of adjacent maximum points comprises two adjacent maximum points in the maximum points; calculating a sum of point serial number differences of the maximum points in all the pairs of adjacent maximum points; wherein the point serial number is the serial number of the maximum point in the corresponding ultrasonic echo judgment set; calculating a difference absolute value between the mean value of all the maximum points and the mean value of the ultrasonic echo compensation data in the current ultrasonic echo judgment set; and determining the time domain overlap amount of the current ultrasonic echo judgment set based on the sum of the point serial number differences and the difference absolute value.

[0040] Preferably, in one embodiment of the present application, the above determining the workpiece structure complexity index based on the time domain overlap amount comprises: performing normalization processing on the time domain overlap amount to determine the workpiece structure complexity index.

[0041] Preferably, in one embodiment of the present application, the above determining the frequency domain offset distortion degree of the current ultrasonic echo judgment set based on the workpiece structure complexity index comprises: obtaining a first energy of the ultrasonic echo compensation data in a first frequency region and a second energy of the ultrasonic echo compensation data in a second frequency region in the current ultrasonic echo judgment set; wherein the frequency of the second frequency region is greater than the frequency of the first frequency region; calculating an energy difference absolute value of the first energy and the second energy; and determining the frequency domain offset distortion degree of the current ultrasonic echo judgment set based on the workpiece structure complexity index and the energy difference absolute value.

[0042] The real-time manner of the above scheme is, for example: The ultrasonic echo parameter values in each compensated judgment set are fitted into a continuous curve by the least square method. Each maximum point in the curve and its corresponding ultrasonic amplitude are obtained , wherein represents the serial number of the maximum point (the serial number in the judgment set, for example, the 10th point is the maximum point, and at this time ).

[0043] Further, the maximum point in the continuous curve has a physical meaning in the ultrasonic echo, that is, a peak value. Therefore, the larger the amplitude , and the smaller the distance difference between the two amplitudes, the higher the corresponding echo time domain overlap amount, which can prove that the real-time state of the workpiece has a greater impact on the robot in the process of judging the distance based on the ultrasonic echo.

[0044] The calculation method of the time domain overlap amount is:

[0045] in, Indicates in The time domain overlap of the echoes in a decision set; Indicates the The difference in sequence numbers between pairs of maximum points; Indicates the total number of maximum point pairs in the judgment set. For example, if there are four maximum points A, B, C, and D, then there are three maximum point pairs, including (A, B), (B, C), and (C, D). Indicates the mean of the maximum echo amplitude; Indicates the mean echo amplitude in the decision set.

[0046] The difference between the maximum echo mean and the normal echo amplitude The quantitative logic is: the more complex the workpiece structure is, the higher the peak value of the corresponding ultrasonic echo is; the sum of the differences between the serial numbers of the maximum value points is The quantification logic is that when ultrasound waves hit the edge or raised area of ​​a workpiece, multiple reflections occur, causing the peaks of the echo signals to overlap irregularly in time. Therefore, the higher the value of the time domain overlap, the greater the time domain overlap, and the greater the impact on the accuracy of the ultrasonic echo.

[0047] After normalizing the above time domain overlap, it can be used as an indicator of the workpiece structural complexity. The closer the indicator is to 1, the higher the structural complexity of the workpiece; conversely, the further the workpiece structural complexity indicator is from 1, the lower the structural complexity of the workpiece.

[0048] It should be noted that the least squares method is a relatively mature fitting method. For its specific implementation, please refer to the relevant technology, and the embodiments of the present invention will not be described in detail.

[0049] It should be further explained that: when the welding robot is closer to the workpiece on the track, the above-mentioned time domain overlap effect may also occur, so the degree of frequency domain offset distortion of the ultrasonic echo judgment set can be further determined. Furthermore, ultrasonic waves will be affected by the surface condition, material properties and temperature of the workpiece during propagation. The increase in temperature further causes the impedance of the metal to change, thereby affecting the frequency response of the echo. For example, higher frequencies may be attenuated more significantly, while low-frequency signals may be relatively more stable. Therefore, in the frequency domain, the signal will be deflected, and the energy corresponding to the low-frequency area will be deflected. Generally higher than the energy corresponding to the high-frequency area , so the energy difference between the two The higher it is, the greater the frequency domain offset and distortion.

[0050] The calculation method of the frequency domain offset distortion degree is:

[0051] in, Indicates the The frequency domain offset distortion degree of the decision set; the dynamic frequency domain offset distortion degree is: different decision sets The higher the degree of dynamic frequency domain offset distortion, that is, the stronger the ultrasonic distortion effect, it can be judged that the welding robot is extremely close to the workpiece or the workpiece surface is overheated and complicated.

[0052] What needs to be explained is that the energy corresponding to the above low-frequency area The energy corresponding to the high-frequency region The calculation method can be: perform Fourier transform on the ultrasonic echo compensation data in the ultrasonic echo judgment set to obtain a spectrum; in the spectrum, calculate the energy of the low-frequency region respectively. and the energy in the high-frequency region . Low frequency area energy Usually corresponds to the lower frequency band, the energy in the high frequency area It is understandable that the signal energy calculation scheme is a relatively mature and well-known technology, and its specific implementation method can be found in the related art, which will not be described in detail in the embodiment of the present invention.

[0053] Step S150: Based on the degree of frequency domain offset distortion, feedback adjustment is performed on the moving speed of the welding robot and the welding speed of the welding track.

[0054] Preferably, in one embodiment of the present invention, the above step S150 may include: Normalizing the dynamic frequency domain offset distortion degree. If the normalized dynamic frequency domain offset distortion degree is greater than a preset alarm threshold, an anti-collision alarm is issued. In addition, the absolute value of the difference between the dynamic frequency domain offset distortion degree corresponding to the current ultrasonic echo judgment set and the dynamic frequency domain offset distortion degree corresponding to the previous ultrasonic echo judgment set is calculated. If the ratio of the absolute value of the difference to the dynamic frequency domain offset distortion degree corresponding to the current ultrasonic echo judgment set is greater than the preset speed adjustment threshold, the moving speed of the welding robot and the welding speed of the welding track are feedback adjusted to reduce the moving speed of the welding robot and the welding speed of the welding track.

[0055] The implementation of the above solution is for example: Current and back difference Greater than offset 50%, it is considered that it is close to the workpiece at this time, and timely feedback is needed to reduce the robot moving speed and the welding speed of the welding track. the normalized value is greater than or equal to At this time, the anti-collision alarm processing is performed, and it is considered that the distance difference between the robot on the track and the workpiece is extremely close at this time, and the welding operation or the movement operation of the robot needs to be stopped immediately.

[0056] It should be noted that when feedback regulation is required for the welding speed of the welding track and the movement speed of the welding robot, the above offset , or the ratio of the above and the offset is used as a feedback regulation parameter, and the welding speed of the welding track and the movement speed of the welding robot are regulated by feedback regulation. In addition, by analyzing the real-time state of the workpiece and obtaining the analysis results of different dynamic states, the anti-collision feedback speed regulation of the robot and the anti-collision instruction issuing are performed according to the results. It is ensured that under complex environment, through the judgment of ultrasonic echo, it still has controllable analysis value, and the real-time collision possibility and the corresponding robot movement speed feedback regulation result are determined according to the dynamic result. It can be understood that feedback regulation is a relatively mature known technology, and its specific implementation mode can be referred to related technologies, and the embodiments of the present application will not be described here.

[0057] Please refer to Figure 2 , which shows a welding robot control system 200 for anti-collision provided by an embodiment of the present application, which comprises a host computer 210, and an infrared sensor 220 and an ultrasonic sensor 230 electrically connected to the host computer, the infrared sensor 220 and the ultrasonic sensor 230 are installed on the welding robot, wherein: The infrared sensor 220 is used to collect the thermal infrared temperature data of the workpiece to be processed in the welding track, and send the thermal infrared temperature data to the host computer 210; The ultrasonic sensor 230 is used to collect the ultrasonic echo data of the workpiece to be processed in the welding track, and send the ultrasonic echo data to the host computer 210; The host computer 210 is used to acquire the thermal infrared temperature data and the ultrasonic echo data; based on the thermal infrared temperature data, the processing state of the workpiece to be processed is determined; based on the processing state, the ultrasonic echo data is compensated to obtain the ultrasonic echo compensation data; the dynamic frequency domain offset distortion degree of the ultrasonic echo compensation data is determined; wherein the dynamic frequency domain offset distortion degree is used to represent the frequency energy distribution distortion intensity of the ultrasonic echo compensation data; based on the dynamic frequency domain offset distortion degree, the movement speed of the welding robot and the welding speed of the welding track are feedback regulated.

[0058] The ultrasonic sensor 230 will be introduced as follows: The parameter configuration of the ultrasonic sensor 230 is as follows: measurement range: 0 m-10 m; frequency: 30 Hz; detection angle: 0°-90°, the detection angle is set by default in a welding scene; resolution: 1-2 mm, which controls the accuracy of distance measurement; and sampling rate: 20 Hz-100 Hz. The embodiment of the present application can be set to 20 Hz, that is, 20 echoes per second, to monitor the reflected signal in real time and calculate the distance.

[0059] In addition, the data uploaded by the sensor can include state information of the sensor in addition to the collected temperature data or ultrasonic echo data, for example, whether the sensor is working normally, whether calibration is needed, etc., which is usually of a bool type. The data transmission mode when the sensor uploads data can be wireless transmission (Wi-Fi\Bluetooth). The data transmission frequency can be set according to the sampling rate and matched with the sampling frequency of the sensor to ensure real-time data transmission.

[0060] It should be noted that the upper computer 210 can realize part or all of the functions of the welding robot control method for collision prevention described above, and the specific implementation mode can be referred to the description of the welding robot control method for collision prevention above, which will not be described here.

[0061] Up to now, the present application is completed.

[0062] To sum up, in the embodiment of the present application, the thermal infrared temperature data and ultrasonic echo data of the workpiece to be processed in the welding track are acquired; the processing state of the workpiece to be processed is determined based on the thermal infrared temperature data; the ultrasonic echo compensation data is acquired by compensating the ultrasonic echo data based on the processing state; the dynamic frequency domain offset distortion degree of the ultrasonic echo compensation data is determined; and the moving speed of the welding robot and the welding speed of the welding track are feedback adjusted based on the dynamic frequency domain offset distortion degree. The present application can still realize real-time and accurate collision prevention control under the condition of limited hardware by the cooperation of the low-power ultrasonic sensor and the infrared temperature sensor, which significantly reduces the system energy consumption. On the other hand, the ultrasonic echo distortion caused by high temperature and complex workpiece surface is effectively eliminated by using temperature compensation and structural complexity identification, which improves the accuracy and reliability of distance detection. On the other hand, the closed-loop feedback mechanism based on the dynamic frequency domain offset amount enables the robot to automatically slow down or stop in milliseconds, avoiding equipment damage and personnel injury. On the other hand, the welding robot control method for collision prevention described above does not require additional high-cost sensors and can be deployed only by software algorithm upgrade, which has good universality and economic promotion value.

[0063] The above only describes the preferred embodiments of the present application and should not be used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the principles of the present application should be included in the protection scope of the present application.

Claims

1. A welding robot control method for anti-collision, characterized in that: The method comprises: Acquiring thermal infrared temperature data and ultrasonic echo data of the workpiece in the welding track; wherein the thermal infrared temperature data and the ultrasonic echo data are collected by an infrared sensor and an ultrasonic sensor deployed on the welding robot, respectively; determining a processing state of the workpiece based on the thermal infrared temperature data; Based on the processing state, the ultrasonic echo data is compensated to obtain ultrasonic echo compensation data; Determining a frequency domain offset distortion degree of the ultrasonic echo compensation data; wherein the frequency domain offset distortion degree is used to characterize the frequency domain energy distribution distortion intensity of the ultrasonic echo compensation data; Based on the frequency domain offset distortion degree, feedback adjustment is performed on the moving speed of the welding robot and the welding speed of the welding track.

2. The control method for a welding robot for collision prevention according to claim 1, characterized in that: Determining the processing state of the workpiece based on the thermal infrared temperature data includes: Acquire a thermal infrared determination set; wherein the thermal infrared determination set includes the thermal infrared temperature data collected by the infrared sensor within a preset period; Calculating an average value of all the thermal infrared temperature data in the current thermal infrared determination set to obtain a first temperature average value; Obtaining a preset number of historical thermal infrared determination sets, calculating an average value of all the thermal infrared temperature data in each of the historical thermal infrared determination sets, and obtaining a second temperature average value; Calculating the sum of the differences between the first temperature average and each of the second temperature averages to obtain a temperature increment sum; Based on the temperature increment sum and the first temperature mean, a processing state coefficient of the workpiece is determined; wherein the processing state coefficient is used to characterize the degree of influence of the workpiece's own temperature on the ultrasonic echo data.

3. The control method for a welding robot for collision prevention according to claim 2, characterized in that: The compensating the ultrasonic echo data based on the processing state to obtain ultrasonic echo compensation data includes: performing normalization processing on the processing state coefficient; If the normalized processing state coefficient is within a preset state coefficient range, it is determined that the ultrasonic echo data needs to be temperature compensated, and the ultrasonic echo data is compensated based on the normalized processing state coefficient to obtain ultrasonic echo compensation data.

4. The control method for a welding robot for collision prevention according to claim 3, characterized in that: The compensating the ultrasonic echo data based on the normalized machining state coefficient to obtain ultrasonic echo compensation data includes: Determining an ultrasonic echo compensation coefficient based on the processing state coefficient and the compensation parameter; wherein the compensation parameter is used to characterize the ultrasonic echo data compensation ratio caused by a unit processing state coefficient change; The ultrasonic echo data is compensated based on the ultrasonic echo compensation coefficient to obtain ultrasonic echo compensation data.

5. The control method for a welding robot for collision prevention according to claim 1, characterized in that: Determining the frequency domain offset distortion degree of the ultrasonic echo compensation data includes: Acquiring an ultrasonic echo determination set; wherein the ultrasonic echo determination set includes the ultrasonic echo compensation data of the ultrasonic echo data collected by the ultrasonic sensor within a preset period; the ultrasonic echo determination set includes a current ultrasonic echo determination set and a preset number of historical ultrasonic echo determination sets; Determining a time domain overlap amount of a current ultrasonic echo determination set based on the ultrasonic echo compensation data in the ultrasonic echo determination set; wherein the time domain overlap amount is used to characterize a multipath superposition degree of the ultrasonic echo compensation data; determining a workpiece structural complexity index based on the time domain overlap; Based on the workpiece structure complexity index, the frequency domain offset distortion degree of the current ultrasonic echo judgment set is determined.

6. The control method for a welding robot for collision prevention according to claim 5, characterized in that: The determining, based on the ultrasonic echo compensation data in the ultrasonic echo determination set, a time domain overlap amount of a current ultrasonic echo determination set includes: fitting the ultrasonic echo compensation data in the ultrasonic echo determination set into a continuous curve; Obtaining a maximum point in the curve and its corresponding ultrasonic amplitude; Obtaining adjacent maximum point pairs; wherein the adjacent maximum point pairs include two adjacent maximum points among the maximum points; Calculating the sum of the point sequence number differences of the maximum value points in all adjacent maximum value point pairs; wherein the point sequence number is the sequence number of the maximum value point in the corresponding ultrasonic echo judgment set; Calculating the absolute value of the difference between the mean of all the maximum points and the mean of the ultrasonic echo compensation data in the current ultrasonic echo determination set; Based on the sum of the point sequence number differences and the absolute value of the differences, a time domain overlap amount of the current ultrasound echo decision set is determined.

7. The control method for a welding robot for collision prevention according to claim 5, characterized in that: Determining the workpiece structure complexity index based on the time domain overlap includes: The time domain overlap amount is normalized to determine a workpiece structure complexity index.

8. The control method for a welding robot for collision prevention according to claim 5, characterized in that: The determining, based on the workpiece structure complexity index, the frequency domain offset distortion degree of the current ultrasonic echo determination set includes: Acquire a first energy in a first frequency region and a second energy in a second frequency region of the ultrasonic echo compensation data in the current ultrasonic echo determination set; wherein the frequency of the second frequency region is greater than the frequency of the first frequency region; calculating an absolute value of an energy difference between the first energy and the second energy; The frequency domain offset distortion degree of the current ultrasonic echo determination set is determined based on the workpiece structure complexity index and the energy difference absolute value.

9. The control method for a welding robot for collision prevention according to claim 1, characterized in that: The feedback adjustment of the moving speed of the welding robot and the welding speed of the welding track based on the frequency domain offset distortion degree includes: Normalizing the frequency domain offset distortion degree, and if the frequency domain offset distortion degree after normalization is greater than a preset alarm threshold, issuing an anti-collision alarm; In addition, the absolute value of the difference between the frequency domain offset distortion degree corresponding to the current ultrasonic echo judgment set and the frequency domain offset distortion degree corresponding to the previous ultrasonic echo judgment set is calculated. If the ratio of the absolute value of the difference to the frequency domain offset distortion degree corresponding to the current ultrasonic echo judgment set is greater than a preset speed adjustment threshold, the moving speed of the welding robot and the welding speed of the welding track are feedback adjusted to reduce the moving speed of the welding robot and the welding speed of the welding track.

10. A welding robot control system for anti-collision, characterized in that: It includes: a host computer and an infrared sensor and an ultrasonic sensor electrically connected to the host computer, wherein the infrared sensor and the ultrasonic sensor are installed on the welding robot, wherein: The infrared sensor is used to collect thermal infrared temperature data of the workpiece in the welding track and send the thermal infrared temperature data to the host computer; The ultrasonic sensor is used to collect ultrasonic echo data of the workpiece in the welding track and send the ultrasonic echo data to the host computer; The host computer is used to obtain the thermal infrared temperature data and the ultrasonic echo data; determine the processing status of the workpiece based on the thermal infrared temperature data; compensate the ultrasonic echo data based on the processing status to obtain ultrasonic echo compensation data; determine the frequency domain offset distortion degree of the ultrasonic echo compensation data; wherein the frequency domain offset distortion degree is used to characterize the frequency domain energy distribution distortion intensity of the ultrasonic echo compensation data; based on the frequency domain offset distortion degree, feedback adjustment is performed on the moving speed of the welding robot and the welding speed of the welding track.

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