A five-axis loading and unloading robot and a method for adaptively adjusting the clamping force of a mechanical claw

Abstract

The present invention relates to the field of mechanical gripper technology, and specifically to a five-axis loading and unloading robot and a method for adaptively adjusting the clamping force of mechanical grippers. The present invention analyzes the pressure data distribution of different areas on each gripper at different moments, obtains the relative force concentration and pressure change deviation of each area on each gripper at each moment, and obtains the degree of workpiece deformation at each moment; obtains the degree of pressure fluctuation anomaly at each moment based on the relative force concentration of different areas on different grippers at each moment, and the fluctuation characteristics of pressure data at different moments in the corresponding area; adjusts the preset initial clamping force based on the degree of pressure fluctuation anomaly at the real time, the degree of workpiece deformation at different moments in the corresponding neighborhood, and the pressure data distribution of all areas on all grippers, and obtains the corrected clamping force at the next moment. The present invention improves the stability of the gripper during the grasping process by adaptively adjusting the clamping force of the mechanical gripper to accurately adjust the clamping force.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical claws, and in particular to a five-axis loading and unloading robot and a method for adaptively adjusting the clamping force of a mechanical claw. Background Art

[0002] A five-axis loading and unloading robot is a highly efficient automated device. Its core advantage in machining workpieces lies in improving machining consistency through multi-angle collaborative operation. Because unfinished workpieces have uneven surfaces, the robot is equipped with a vision recognition and force control system to adjust gripping force and path to avoid scratches. Therefore, clamping force analysis is necessary.

[0003] In the existing technology, the clamping force of the mechanical claw is determined by program preset to clamp the workpiece. However, when dealing with workpieces with different shapes or surface characteristics, the preset clamping force may have the risk of excessive clamping force causing deformation or unstable clamping. It is inefficient and difficult to adapt to dynamic working conditions, and the adaptive adjustment effect of the clamping force is poor. Summary of the Invention

[0004] In order to solve the technical problem that the clamping force preset by the program cannot adapt to different workpieces and the clamping force adaptive adjustment effect is poor, the purpose of the present invention is to provide a five-axis loading and unloading robot and a method for adaptively adjusting the clamping force of a mechanical claw. The technical solution adopted is as follows:

[0005] The present invention proposes a five-axis loading and unloading robot, comprising a robot body, a controller, and a pressure detector connected to the controller by signal. The pressure detector is used to detect pressure data of different areas on each gripper when the robot's mechanical gripper grips a workpiece. The control method of the controller includes:

[0006] Obtain pressure data of different areas on each gripper when the gripper grips the workpiece at each moment;

[0007] According to the pressure data distribution of different areas on each jaw at each moment, the relative force concentration of each area on each jaw at each moment is obtained; according to the pressure data change trend of each area on each jaw at different moments, the pressure change deviation degree of each area on each jaw at each moment is obtained;

[0008] The degree of workpiece deformation at each moment is obtained based on the relative force concentration in different areas of different jaws at each moment and the degree of pressure change deviation. The degree of pressure fluctuation anomaly at each moment is obtained based on the relative force concentration in different areas of different jaws at each moment and the fluctuation characteristics of pressure data at different moments in the corresponding areas.

[0009] The preset initial clamping force is adjusted according to the abnormal degree of pressure fluctuation at the real time, the deformation degree of the workpiece at different times within the corresponding neighborhood range, and the pressure data distribution of all areas on all clamping jaws to obtain the corrected clamping force at the next moment.

[0010] Furthermore, the method for obtaining the relative force concentration degree includes:

[0011] At any moment, the fluctuation degree of the pressure data of all areas on each gripper is obtained as the pressure fluctuation degree of each gripper;

[0012] The pressure data of each area on each clamp at each moment is normalized, and the product of the normalized result and the pressure fluctuation degree is calculated as the relative force concentration degree of each area on each clamp at each moment.

[0013] Furthermore, the method for obtaining the pressure change deviation degree includes:

[0014] According to the pressure data change trend of each area on each gripper at different times, the pressure change degree of each area on each gripper at each moment is obtained;

[0015] Obtain the average value of the pressure change of each area on each gripper at all times within the neighborhood range of each moment as the basic value of the pressure change of each area on each gripper at each moment;

[0016] Obtain the difference between the basic value of pressure change and the degree of pressure change in each area on each gripper at each moment. If the difference is greater than the preset difference threshold, use the corresponding difference as the degree of deviation of pressure change in each area on each gripper at each moment; if the difference is less than the preset difference threshold, use the corresponding preset difference threshold as the degree of deviation of pressure change in each area on each gripper at each moment.

[0017] Furthermore, the method for obtaining the degree of pressure change includes:

[0018] The difference in pressure data of each area on each jaw between each moment and the previous moment is obtained and normalized to serve as the degree of pressure change of each area on each jaw at each moment.

[0019] Furthermore, the method for obtaining the deformation degree of the workpiece includes:

[0020] Normalize the relative force concentration of each area on each gripper at each moment, and calculate the product of the normalized result and the pressure change deviation as the first product;

[0021] The maximum value of the first product corresponding to all areas on all jaws at each moment is selected as the deformation degree of the workpiece at each moment.

[0022] Furthermore, the method for obtaining the degree of abnormal pressure fluctuation includes:

[0023] Obtain the extreme value of the pressure data of each area on each gripper at all times within the domain range of each moment, obtain the mean difference between all adjacent extreme values ​​at corresponding moments, and perform negative correlation mapping as the pressure fluctuation frequency of each area on each gripper;

[0024] The relative force concentration degree of each area on each clamp at each moment is normalized, and the product of the normalized result and the pressure fluctuation frequency of all areas on all clamps at each moment is calculated as the pressure fluctuation abnormality degree at each moment.

[0025] Furthermore, the method for obtaining the corrected clamping force includes:

[0026] According to the pressure data distribution of all areas on all jaws at each moment, the relative force concentration of each area on each jaw at each moment is obtained;

[0027] If there is a time within the neighborhood of the real-time moment where the workpiece deformation degree is greater than or equal to the preset degree threshold, the maximum value at the corresponding time is used as the reference time, and the deformation pressure threshold at the real-time moment is obtained based on the relative force concentration and pressure data of all areas on all grippers at the reference time;

[0028] The preset initial clamping force is adjusted according to the real-time deformation pressure threshold, the relative force concentration in all areas of all clamping jaws at the real-time moment, and the abnormal pressure fluctuation to obtain the corrected clamping force at the next moment;

[0029] If there is no time within the neighborhood of the real-time moment when the workpiece deformation degree is greater than or equal to the preset degree threshold, the product of the positive integer 1 and the abnormal degree of pressure fluctuation at the real-time moment is calculated as the adjustment weight; the product between the adjustment weight and the preset initial clamping force is obtained as the corrected clamping force at the next moment.

[0030] Furthermore, the preset initial clamping force is adjusted according to the deformation pressure threshold at the real time, the relative force concentration in all areas of all clamping jaws at the real time, and the abnormal pressure fluctuation to obtain the corrected clamping force at the next moment, including:

[0031] Obtaining the ratio between the deformation pressure threshold at real time and the maximum relative force concentration in all areas of all jaws as the upper limit of the clamping force adjustment at real time;

[0032] The difference between the clamping force adjustment upper limit at the real time and the preset initial clamping force is obtained as the first difference; the product of the first difference and the degree of pressure fluctuation abnormality at the real time is calculated, and the sum of the product result and the preset initial clamping force is calculated as the corrected clamping force at the next moment.

[0033] Furthermore, the method for obtaining the deformation pressure threshold includes:

[0034] The product of the maximum relative force concentration, the average pressure data and the preset protection coefficient in all areas of all grippers at the reference moment within the neighborhood of the real-time moment is obtained as the deformation pressure threshold at the real-time moment.

[0035] The present invention also proposes a method for adaptively adjusting the clamping force of a mechanical claw of a five-axis loading and unloading robot, the method comprising:

[0036] Obtain pressure data of different areas on each gripper when the gripper grips the workpiece at each moment;

[0037] According to the pressure data distribution of different areas on each jaw at each moment, the relative force concentration of each area on each jaw at each moment is obtained; according to the pressure data change trend of each area on each jaw at different moments, the pressure change deviation degree of each area on each jaw at each moment is obtained;

[0038] The degree of workpiece deformation at each moment is obtained based on the relative force concentration in different areas of different jaws at each moment and the degree of pressure change deviation. The degree of pressure fluctuation anomaly at each moment is obtained based on the relative force concentration in different areas of different jaws at each moment and the fluctuation characteristics of pressure data at different moments in the corresponding areas.

[0039] The preset initial clamping force is adjusted according to the abnormal degree of pressure fluctuation at the real time, the deformation degree of the workpiece at different times within the corresponding neighborhood range, and the pressure data distribution of all areas on all clamping jaws to obtain the corrected clamping force at the next moment.

[0040] The present invention has the following beneficial effects:

[0041] The present invention obtains the relative force concentration of each area on each jaw at each moment based on the pressure data distribution of different areas on each jaw at each moment, identifies the force levels of the jaw and each area, and helps to understand the pressure distribution; obtains the pressure change deviation of each area on each jaw at each moment based on the pressure data change trend of each area on each jaw at different moments, and dynamically analyzes the pressure change characteristics of each area; obtains the deformation degree of the workpiece at each moment based on the relative force concentration of different areas on different jaws at each moment and the pressure change deviation, and more accurately analyzes the deformation degree of the workpiece by considering the static pressure concentration distribution and dynamic change anomalies; obtains the pressure fluctuation anomaly at each moment based on the relative force concentration of different areas on different jaws at each moment and the fluctuation characteristics of pressure data at different moments in the corresponding areas, and more accurately quantifies the dynamic change characteristics of the pressure data of each area of ​​the jaw; adjusts the preset initial clamping force based on the real-time pressure fluctuation anomaly, the workpiece deformation degree at different moments in the corresponding neighborhood range, and the pressure data distribution of all areas on all jaws to obtain a corrected clamping force at the next moment. The present invention accurately adjusts the clamping force of the mechanical claw by adaptively adjusting the clamping force, thereby improving the stability of the clamp during the grasping process. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 A schematic structural diagram of a five-axis loading and unloading robot provided by one embodiment of the present invention;

[0044] Figure 2 A flow chart of a control method provided by one embodiment of the present invention;

[0045] Figure 3 A flow chart of a method for obtaining a pressure variation deviation degree provided by one embodiment of the present invention;

[0046] Figure 4 A flow chart of a method for obtaining a corrected clamping force provided by one embodiment of the present invention.

[0047] Figure 1Among them, 1 is the movable axis responsible for controlling the transposition and lateral movement of the robot arm; 2 is the movable axis responsible for the lateral movement of the robot arm; 3 is the movable axis responsible for the lateral movement of the material tray; 4 is the movable axis responsible for the up and down movement of the robot arm; 5 is the movable axis responsible for the rotation of the robot arm; 6 is the material tray responsible for storing the workpiece; 7 is the electrical cabinet responsible for providing power to and controlling the five-axis loading and unloading robot; 8 is the robotic claw. DETAILED DESCRIPTION

[0048] To further illustrate the technical means and effectiveness of the present invention in achieving its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, describes in detail the specific implementation, structure, features, and effectiveness of a five-axis loading and unloading robot and a method for adaptively adjusting the clamping force of a mechanical gripper, according to the present invention. In the following description, references to different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0049] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0050] The following describes in detail a five-axis loading and unloading robot and a specific scheme of a method for adaptively adjusting the clamping force of a mechanical claw provided by the present invention in conjunction with the accompanying drawings.

[0051] One embodiment of the present invention provides a five-axis loading and unloading robot, including a robot body, the robot body including a structure reference Figure 1 , which shows a structural schematic diagram of a five-axis loading and unloading robot: movable axes 1-5, material tray 6, electrical cabinet 7, and mechanical claw 8; through the movable axes 1-5, the mechanical claw 8 is moved to the material tray 6 to grab and clamp the rough workpiece; through the movable axis 5, the mechanical arm is rotated to place the rough workpiece into the processing area of ​​the CNC machining equipment; after processing, the finished workpiece is grabbed and clamped and placed in the finished product collection area, completing the workpiece loading and unloading operation; it also includes a controller and a pressure detector connected to the controller signal. The pressure detector is used to detect the pressure data of different areas on each clamping claw when the robot's mechanical claw grabs the workpiece. For the control method of the controller, please refer to Figure 2 , which shows a flow chart of a control method provided by an embodiment of the present invention, specifically comprising:

[0052] Step S1: Obtain pressure data of different areas on each gripper when the gripper grips the workpiece at each moment.

[0053] In an embodiment of the present invention, to avoid deformation of the workpiece caused by excessive or insufficient clamping force during gripping, it is necessary to analyze the pressure during gripping. First, a pneumatically driven mechanical gripper is used to grip workpieces such as blanks and finished parts. The contact surface between each jaw of the mechanical gripper and the workpiece is evenly divided longitudinally into multiple regions. The present invention divides the regions into four regions. A PVDF piezoelectric film sensor is placed on the silicone pad within each region to obtain pressure data during the gripping process of the mechanical gripper. The pressure data of different regions on each jaw at each moment when the mechanical gripper grips the workpiece is obtained. It should be noted that in one embodiment of the present invention, the workpiece to be analyzed is an aluminum product. Each jaw grips the workpiece with a preset initial clamping force of 2N. The pressure values ​​of different regions on each jaw at each moment when the mechanical gripper grips the workpiece are obtained at a frequency of 1kHz, that is, every 0.001 second. In other embodiments of the present invention, the preset initial clamping force and frequency can be set according to the specific situation and are not limited or elaborated here.

[0054] Step S2: According to the pressure data distribution of different areas on each clamp at each moment, the relative force concentration of each area on each clamp at each moment is obtained; according to the pressure data change trend of each area on each clamp at different moments, the pressure change deviation degree of each area on each clamp at each moment is obtained.

[0055] During the gripping process of the five-axis loading and unloading robot, since the workpiece is not completely processed, there are casting residues or original concave and convex textures on the surface before processing. The more preferential contact the raised area is, the more concentrated pressure it is subjected to, while the pressure in the recessed area is significantly reduced due to incomplete fit, and the force is smaller. Therefore, by analyzing the pressure data distribution of different areas on each gripper, we can more clearly understand the relative force concentration degree of different areas; according to the pressure data distribution of different areas on each gripper at each moment, we can obtain the relative force concentration degree of each area on each gripper at each moment.

[0056] Preferably, in one embodiment of the present invention, the method for obtaining the relative force concentration degree includes:

[0057] At any moment, the fluctuation degree of the pressure data of all areas on each gripper is obtained as the pressure fluctuation degree of each gripper;

[0058] The pressure data of each area on each clamp at each moment is normalized, and the product of the normalized result and the pressure fluctuation degree is calculated as the relative force concentration degree of each area on each clamp at each moment.

[0059] In one embodiment of the present invention, for each moment, the formula for the relative force concentration degree is expressed as:

[0060]

[0061] Among them, A a,b Indicates the relative force concentration of the bth area on the ath gripper; C a Indicates the degree of fluctuation of the pressure data of all areas on the a-th gripper, that is, the degree of pressure fluctuation; B a,b Indicates the pressure data of the bth area on the ath gripper; B a Represents the cumulative pressure data of all areas on the a-th gripper.

[0062] In the formula for relative force concentration, It represents the value of the pressure data of the bth area on the ath jaw divided by the cumulative sum of the pressure data of all areas, that is, the pressure data of each area on each jaw at each moment is normalized. The larger the pressure data of the bth area on the ath jaw, the more force the bth area on the ath jaw is subjected to than other areas, and the greater the relative force concentration of the bth area on the ath jaw; the greater the fluctuation of the pressure data of all areas on the ath jaw, the more uneven the force distribution on the corresponding jaw, the more likely there is a bulge, the greater the possibility of force concentration in the area, and the greater the relative force concentration.

[0063] It should be noted that, in one embodiment of the present invention, the degree of fluctuation can be expressed by calculating the variance. The larger the variance, the greater the degree of fluctuation, and the smaller the variance, the smaller the degree of fluctuation. In other embodiments of the present invention, the degree of fluctuation can also be expressed by calculating the standard deviation or range. The specific means are technical means well known to those skilled in the art and are not limited or elaborated here.

[0064] When the jaws are too tight, the pressure will significantly exceed the critical point of deformation of the workpiece, causing plastic deformation; the smaller the contact area between the jaws and the workpiece, the greater the stress concentration effect, and the more the workpiece enters the plastic stage. As the clamping process progresses, the pressure data of the jaws first increases. When the pressure reaches the elastic limit of the workpiece, the workpiece's ability to resist deformation decreases, causing the pressure growth rate to slow down or become flat, and the pressure change deviation becomes greater; therefore, based on the pressure data change trend of each area on each jaw at different times, the pressure change deviation of each area on each jaw at each moment is obtained.

[0065] Preferably, in one embodiment of the present invention, the method for obtaining the pressure variation deviation degree can be found in Figure 3 , which shows a flow chart of a method for obtaining a pressure variation deviation degree provided by one embodiment of the present invention, including:

[0066] Step S301: Obtain the pressure change degree of each area on each clamping jaw at each moment according to the pressure data change trend of each area on each clamping jaw at different moments.

[0067] Preferably, in one embodiment of the present invention, the method for obtaining the pressure change degree includes:

[0068] The difference in pressure data of each area on each jaw between each moment and the previous moment is obtained and normalized to serve as the degree of pressure change of each area on each jaw at each moment.

[0069] The smaller the difference, the slower the pressure data increases, and the more likely it is to be affected by deformation.

[0070] Step S302: Obtain the average value of the pressure change degree of each area on each clamp at all times within the neighborhood range of each moment as the basic value of the pressure change of each area on each clamp at each moment.

[0071] The pressure change degree corresponding to all moments in the neighborhood is quantified by taking the average value, reflecting the overall pressure level and providing a benchmark for subsequent data comparison.

[0072] It should be noted that, in one embodiment of the present invention, the size of the neighborhood range is based on each moment and is composed of a preset number of historical moments, where the preset number is 50; in other embodiments of the present invention, the size of the neighborhood range can be set according to specific circumstances, and is not limited or elaborated here.

[0073] Step S303: Obtain the difference between the basic value of pressure change and the degree of pressure change in each area on each clamp at each moment. If the difference is greater than the preset difference threshold, the corresponding difference is used as the degree of deviation of pressure change in each area on each clamp at each moment; if the difference is less than the preset difference threshold, the corresponding preset difference threshold is used as the degree of deviation of pressure change in each area on each clamp at each moment.

[0074] In one embodiment of the present invention, the formula for the pressure variation deviation degree is expressed as:

[0075] D c,a,b =MAX((E c,a,b -F c,a,b ),α);

[0076] Among them, D c,a,b Indicates the deviation of the pressure change in the bth area on the ath gripper at the cth moment; E c,a,b F represents the basic value of pressure change in the bth area on the ath gripper at the cth moment; c,a,b It represents the pressure change degree of the bth area on the ath gripper at the cth moment; MAX() represents the maximum value function; α represents the preset difference threshold.

[0077] In the formula for the degree of deviation of pressure change, Ec,a,b -F c,a,b It represents the difference between the pressure change base value and the pressure change degree of the bth area on the ath jaw at the cth moment. The larger the difference, the greater the pressure change base value relative to the pressure change degree, the slower or more stable the pressure increase, the lower the ability of the workpiece to resist deformation, and the more likely a larger pressure deviation will occur. If the pressure change base value of the bth area on the ath jaw at the cth moment is smaller than the pressure change degree, the smaller the difference, the smaller the pressure change base value relative to the pressure change degree, the more the pressure shows a trend of continuous increase, and the smaller the pressure change deviation.

[0078] It should be noted that, in the embodiment of the present invention, the preset difference threshold α is 0.

[0079] Step S3: According to the relative force concentration of different areas on different jaws at each moment and the degree of pressure change deviation, the degree of workpiece deformation at each moment is obtained; according to the relative force concentration of different areas on different jaws at each moment and the fluctuation characteristics of pressure data at different moments in the corresponding areas, the degree of pressure fluctuation abnormality at each moment is obtained.

[0080] When the gripper is gripping, if the clamping force is too large, it is more likely to cause extrusion deformation at the position with greater pressure, and the greater the degree of deformation, the relative force concentration can reflect the pressure intensity of the mechanical gripper on the workpiece surface. The greater the relative force concentration, the greater the clamping force of the mechanical gripper may be; the pressure change deviation can reflect the dynamic change of pressure. The greater the pressure change deviation, the more likely the workpiece's ability to resist deformation has changed differently; according to the relative force concentration of different areas on different grippers at each moment, and the pressure change deviation, the workpiece deformation degree at each moment is obtained.

[0081] Preferably, in one embodiment of the present invention, the method for obtaining the deformation degree of the workpiece includes:

[0082] Normalize the relative force concentration of each area on each gripper at each moment, and calculate the product of the normalized result and the pressure change deviation as the first product;

[0083] The maximum value of the first product corresponding to all areas on all jaws at each moment is selected as the deformation degree of the workpiece at each moment.

[0084] In one embodiment of the present invention, the formula for the degree of deformation of the workpiece is expressed as:

[0085] G c =MAX(norm(A c,a,b )×D c,a,b );

[0086] Among them, Gc Indicates the deformation degree of the workpiece at the cth moment; A c,a,b Indicates the relative force concentration of the bth area on the ath gripper at the cth moment; D c,a,b It represents the deviation of the pressure change in the bth area on the ath gripper at the cth moment; norm() represents the normalization function; MAX() represents the maximum value function.

[0087] In the formula for the degree of workpiece deformation, the greater the relative force concentration in the bth area on the ath jaw at the cth moment, the greater the force in the corresponding jaw area, and the more likely the clamping force is to be excessive; the greater the deviation in the pressure change in the bth area on the ath jaw at the cth moment, and the more obvious the pressure change, the more likely deformation has occurred, and the greater the degree of workpiece deformation.

[0088] When the clamping force is relatively low, the workpiece can slide and fall due to gravity, causing a sudden change in the dynamic friction between the workpiece and the clamping jaws. The greater the fluctuation characteristics of the pressure data at different moments, the greater the degree of pressure fluctuation anomaly. The degree of pressure fluctuation anomaly at each moment is determined by the relative force concentration in different areas of the clamping jaws at each moment and the fluctuation characteristics of the pressure data at different moments in these areas.

[0089] Preferably, in one embodiment of the present invention, the method for obtaining the degree of abnormal pressure fluctuation includes:

[0090] Obtain the extreme value of the pressure data of each area on each gripper at all times within the domain range of each moment, obtain the mean difference between all adjacent extreme values ​​at corresponding moments, and perform negative correlation mapping as the pressure fluctuation frequency of each area on each gripper;

[0091] The relative force concentration degree of each area on each clamp at each moment is normalized, and the product of the normalized result and the pressure fluctuation frequency of all areas on all clamps at each moment is calculated as the pressure fluctuation abnormality degree at each moment.

[0092] In one embodiment of the present invention, the formula for the degree of abnormal pressure fluctuation is expressed as:

[0093]

[0094] Among them, M c represents the abnormal degree of pressure fluctuation at the cth moment; Q represents the number of jaws; P represents the number of areas on each jaw; A c,a,b Indicates the relative force concentration of the bth area on the ath gripper at the cth moment; N c,a,b represents the pressure fluctuation frequency of the bth area on the ath gripper at the cth moment; softmax() represents the normalization function.

[0095] In the formula for the degree of pressure fluctuation anomaly, the greater the relative force concentration, the greater the pressure fluctuation frequency, which can reflect that the greater the force, the more frequent the fluctuations, and the greater the degree of pressure fluctuation anomaly.

[0096] It should be noted that, in one embodiment of the present invention, the method for obtaining the extreme value is: if there is any moment where the corresponding pressure data is greater than or less than the pressure data at the adjacent previous and next moments, the pressure data at the corresponding moment is taken as the extreme value; in other embodiments of the present invention, the extreme value can also be obtained by Newton's method. The specific means are technical means well known to those skilled in the art and will not be elaborated here.

[0097] Step S4: Adjust the preset initial clamping force according to the abnormal degree of pressure fluctuation at the real time, the deformation degree of the workpiece at different times within the corresponding neighborhood range, and the pressure data distribution of all areas on all clamping jaws to obtain the corrected clamping force at the next moment.

[0098] Pressure fluctuations reflect contact stability. The greater the pressure fluctuations, the lower the contact stability, and the more likely it is that the corrective clamping force for the next moment will need to be adjusted. Deformation is a reflection of the workpiece's tolerance, and the degree of deformation reflects the extent of deformation. The greater the workpiece deformation, the greater the clamping force of the clamp, and the more likely it is that the corrective clamping force for the next moment will need to be adjusted. Therefore, analyzing the degree of pressure fluctuation anomalies, the degree of workpiece deformation, and pressure data helps to understand the pressure changes in the clamp and the deformation state of the workpiece, and to more comprehensively and accurately evaluate the corrective clamping force for the next moment.

[0099] Preferably, in one embodiment of the present invention, the method for obtaining the corrected clamping force is as follows: Figure 4 , which shows a flow chart of a method for obtaining a corrected clamping force provided by one embodiment of the present invention, including:

[0100] Step S401: According to the pressure data distribution of all areas on all clamping jaws at each moment, the relative force concentration degree of each area on each clamping jaw at each moment is obtained.

[0101] The relative force concentration reflects the force concentration in the area on the clamping jaws, which helps to understand the pressure intensity characteristics when the clamping force is applied to the workpiece.

[0102] Step S402: If there is a moment in the neighborhood of the real-time moment where the workpiece deformation degree is greater than or equal to the preset degree threshold, the maximum value in the corresponding moment is used as the reference moment, and the deformation pressure threshold at the real-time moment is obtained based on the relative force concentration and pressure data of all areas on all clamps at the reference moment.

[0103] The degree of deformation of the workpiece reflects the possibility of deformation of the workpiece. The greater the degree of deformation of the workpiece, the greater the possibility of deformation, and the more necessary it is to analyze the deformation characteristics of the workpiece. It should be noted that, in one embodiment of the present invention, the size of the preset degree threshold is 0.5, that is, the moment when the degree of deformation of the workpiece is greater than or equal to 0.5 is selected, and the maximum value in the corresponding moment is used as the reference moment. In other embodiments of the present invention, the size of the preset degree threshold can be set according to the specific situation, and is not limited or elaborated here.

[0104] Preferably, in one embodiment of the present invention, the method for obtaining the deformation pressure threshold includes:

[0105] The product of the maximum relative force concentration, the average pressure data and the preset protection coefficient in all areas of all grippers at the reference moment within the neighborhood of the real-time moment is obtained as the deformation pressure threshold at the real-time moment.

[0106] It should be noted that, in the embodiment of the present invention, the average pressure data is the average of the pressure data of all areas on all the clamping jaws at a real time moment, that is, the average pressure data.

[0107] It should be noted that, in one embodiment of the present invention, the preset protection coefficient is 0.9; in one embodiment of the present invention, the preset protection coefficient can be set according to specific circumstances, which is not limited or elaborated here.

[0108] Step S403: adjusting the preset initial clamping force according to the real-time deformation pressure threshold, the relative force concentration in all areas of all clamping jaws at the real-time moment, and the abnormal pressure fluctuation to obtain the corrected clamping force at the next moment.

[0109] It should be noted that, in one embodiment of the present invention, the preset initial clamping force is adjusted based on the real-time deformation pressure threshold, the relative force concentration in all areas of all jaws at the real-time moment, and the abnormal pressure fluctuation to obtain the corrected clamping force at the next moment, including:

[0110] Obtaining the ratio between the deformation pressure threshold at real time and the maximum relative force concentration in all areas of all jaws as the upper limit of the clamping force adjustment at real time;

[0111] The difference between the clamping force adjustment upper limit at the real time and the preset initial clamping force is obtained as the first difference; the product of the first difference and the degree of pressure fluctuation abnormality at the real time is calculated, and the sum of the product result and the preset initial clamping force is calculated as the corrected clamping force at the next moment.

[0112] In one embodiment of the present invention, the formula for correcting the clamping force is expressed as:

[0113] R i+1 =S+(T i -S)×M i ;

[0114]

[0115] Among them, R i+1 represents the corrected clamping force at the next moment i+1; S represents the preset initial clamping force; M i Indicates the abnormal degree of pressure fluctuation at real time i; T i represents the upper limit of the clamping force adjustment at the real-time moment i; L represents the deformation pressure threshold at the real-time moment; MAX(A) represents the maximum relative force concentration in all areas of all clamps at the real-time moment.

[0116] In the formula for correcting the clamping force, the greater the maximum value of the relative force concentration, the greater the regional force distribution when the workpiece is clamped, and the more the clamping force needs to be reduced to avoid excessive regional force. In order to avoid deformation of the workpiece, an analysis is performed based on the obtained deformation pressure threshold. The greater the deformation pressure threshold, the greater the tolerable clamping force and the larger the upper limit of the clamping force adjustment; (T i -S) represents the difference between the upper limit of the clamping force adjustment at the real time and the preset initial clamping force, which is used as the first difference. The larger the first difference is, the larger the upper limit of the clamping force adjustment is than the preset initial clamping force, and the greater the degree of adjustment of the clamping force. If the first difference is smaller, the closer it is to the upper limit of the clamping force adjustment, the smaller the degree of adjustment of the clamping force.

[0117] For those with a deformation pressure threshold, in order to avoid excessive clamping force, the adjustment of the preset initial clamping force cannot be greater than the clamping force adjustment upper limit, and the difference between the clamping force adjustment upper limit and the preset initial clamping force at the real time is obtained as the first difference. If the preset initial clamping force is larger than the clamping force adjustment upper limit, the first difference is smaller, and in the negative direction, the smaller the clamping force is adjusted, the smaller the corrected clamping force at the next moment.

[0118] Step S404: If there is no time within the neighborhood of the real-time moment where the workpiece deformation degree is greater than or equal to the preset degree threshold, calculate the product of the positive integer 1 and the pressure fluctuation abnormality degree at the real-time moment as the adjustment weight; obtain the product between the adjustment weight and the preset initial clamping force as the corrected clamping force at the next moment.

[0119] In one embodiment of the present invention, the formula for correcting the clamping force is expressed as:

[0120] R i+1 =S×(1+M i );

[0121] Among them, R i+1represents the corrected clamping force at the next moment i+1; S represents the preset initial clamping force; M i Indicates the abnormal degree of pressure fluctuation at real time i; T i Indicates the upper limit of the clamping force adjustment at real time i.

[0122] In the formula for correcting the clamping force, there is no deformation threshold for the workpiece. The greater the abnormal pressure fluctuation, the more likely the workpiece will slip due to insufficient clamping force. The more clamping is needed, and the larger the corrected clamping force needs to be.

[0123] Based on this, the preset initial clamping force is adjusted according to the different morphological characteristics of the workpiece to improve the stability of the workpiece clamping process and avoid damage to the loading and unloading caused by excessive or insufficient clamping force.

[0124] It should be noted that, when obtaining the adjusted corrected clamping force, it is considered that when the clamping force is the upper limit of adjustment, gravity may not be offset and the mechanical claw may not be able to grasp the workpiece. If the difference between the corrected clamping force and the preset initial clamping force is less than the preset difference threshold, the size of the preset difference threshold can be set according to the specific situation. For example, the preset difference threshold is 0.01. The smaller the corresponding adjustment range, the more difficult it is for the robot to perform adaptive adjustment and an alarm is required to check whether the quality of the workpiece is qualified. For qualified workpieces, the silicone pad of the mechanical claw can be replaced to improve the stability of the mechanical claw in grasping the workpiece.

[0125] In summary, the present invention analyzes the pressure data distribution of different areas on each jaw at different times to obtain the relative force concentration and pressure change deviation of each area on each jaw at each moment, and obtains the workpiece deformation degree at each moment; according to the relative force concentration of different areas on different jaws at each moment, and the fluctuation characteristics of the pressure data at different moments in the corresponding area, the pressure fluctuation abnormality at each moment is obtained; according to the real-time pressure fluctuation abnormality, the workpiece deformation degree at different moments in the corresponding neighborhood, and the pressure data distribution of all areas on all jaws, the preset initial clamping force is adjusted to obtain the corrected clamping force at the next moment. The present invention improves the stability of the gripping process of the jaws by adaptively adjusting the clamping force of the mechanical jaws accurately.

[0126] The present invention also proposes a method for adaptively adjusting the clamping force of a mechanical claw of a five-axis loading and unloading robot, the method comprising:

[0127] Obtain pressure data of different areas on each gripper of the mechanical gripper when gripping the workpiece at each moment;

[0128] According to the pressure data distribution of different areas on each jaw at each moment, the relative force concentration of each area on each jaw at each moment is obtained; according to the pressure data change trend of each area on each jaw at different moments, the pressure change deviation degree of each area on each jaw at each moment is obtained;

[0129] The degree of workpiece deformation at each moment is obtained based on the relative force concentration in different areas of different jaws at each moment and the degree of pressure change deviation. The degree of pressure fluctuation anomaly at each moment is obtained based on the relative force concentration in different areas of different jaws at each moment and the fluctuation characteristics of pressure data at different moments in the corresponding areas.

[0130] The preset initial clamping force is adjusted according to the abnormal degree of pressure fluctuation at the real time, the deformation degree of the workpiece at different times within the corresponding neighborhood range, and the pressure data distribution of all areas on all clamping jaws to obtain the corrected clamping force at the next moment.

[0131] It should be understood that the adaptive adjustment method of the clamping force of the mechanical claw of a five-axis loading and unloading robot provided in this embodiment is applied to execute the above-mentioned five-axis loading and unloading robot, and therefore has the same steps and beneficial effects as the control method adopted, run or implemented by the application program stored therein.

[0132] It should be noted that the order in which the embodiments of the present invention are described above is for illustrative purposes only and does not necessarily represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0133] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

Claims

1. A five-axis loading and unloading robot, comprising a robot body, characterized in that: The robot also includes a controller and a pressure detector connected to the controller signal, wherein the pressure detector is used to detect pressure data of different areas on each gripper when the robot's mechanical gripper grips a workpiece. The control method of the controller includes: Obtain pressure data of different areas on each gripper when the gripper grips the workpiece at each moment; According to the pressure data distribution of different areas on each jaw at each moment, the relative force concentration of each area on each jaw at each moment is obtained; according to the pressure data change trend of each area on each jaw at different moments, the pressure change deviation degree of each area on each jaw at each moment is obtained; The degree of workpiece deformation at each moment is obtained based on the relative force concentration in different areas of different jaws at each moment and the degree of pressure change deviation. The degree of pressure fluctuation anomaly at each moment is obtained based on the relative force concentration in different areas of different jaws at each moment and the fluctuation characteristics of pressure data at different moments in the corresponding areas. The preset initial clamping force is adjusted based on the degree of abnormal pressure fluctuation at the real time, the degree of workpiece deformation at different times within the corresponding neighborhood, and the pressure data distribution of all areas on all clamping jaws to obtain the corrected clamping force at the next moment; The method for obtaining the corrected clamping force includes: According to the pressure data distribution of all areas on all jaws at each moment, the relative force concentration of each area on each jaw at each moment is obtained; If there is a time within the neighborhood of the real-time moment where the workpiece deformation degree is greater than or equal to the preset degree threshold, the maximum value at the corresponding time is used as the reference time, and the deformation pressure threshold at the real-time moment is obtained based on the relative force concentration and pressure data of all areas on all grippers at the reference time; The preset initial clamping force is adjusted according to the real-time deformation pressure threshold, the relative force concentration in all areas of all clamping jaws at the real-time moment, and the abnormal pressure fluctuation to obtain the corrected clamping force at the next moment; If there is no workpiece deformation degree greater than or equal to the preset degree threshold at a time within the neighborhood of the real time, the product of the positive integer 1 and the abnormal degree of pressure fluctuation at the real time is calculated as the adjustment weight; the product between the adjustment weight and the preset initial clamping force is obtained as the corrected clamping force at the next time; The preset initial clamping force is adjusted according to the deformation pressure threshold at the real time, the relative force concentration in all areas of all clamping jaws at the real time, and the abnormal pressure fluctuation to obtain the corrected clamping force at the next moment, including: Obtaining the ratio between the deformation pressure threshold at real time and the maximum relative force concentration in all areas of all jaws as the upper limit of the clamping force adjustment at real time; The difference between the clamping force adjustment upper limit at the real time and the preset initial clamping force is obtained as the first difference; the product of the first difference and the degree of pressure fluctuation abnormality at the real time is calculated, and the sum of the product result and the preset initial clamping force is calculated as the corrected clamping force at the next moment.

2. A five-axis loading and unloading robot according to claim 1, characterized in that: The method for obtaining the relative force concentration degree includes: At any moment, the fluctuation degree of the pressure data of all areas on each gripper is obtained as the pressure fluctuation degree of each gripper; The pressure data of each area on each clamp at each moment is normalized, and the product of the normalized result and the pressure fluctuation degree is calculated as the relative force concentration degree of each area on each clamp at each moment.

3. The five-axis loading and unloading robot according to claim 1, characterized in that: The method for obtaining the pressure change deviation degree includes: According to the pressure data change trend of each area on each gripper at different times, the pressure change degree of each area on each gripper at each moment is obtained; Obtain the average value of the pressure change of each area on each gripper at all times within the neighborhood range of each moment as the basic value of the pressure change of each area on each gripper at each moment; Obtain the difference between the basic value of pressure change and the degree of pressure change in each area on each gripper at each moment. If the difference is greater than the preset difference threshold, use the corresponding difference as the degree of deviation of pressure change in each area on each gripper at each moment; if the difference is less than the preset difference threshold, use the corresponding preset difference threshold as the degree of deviation of pressure change in each area on each gripper at each moment.

4. The five-axis loading and unloading robot according to claim 3, characterized in that: The method for obtaining the pressure change degree includes: The difference in pressure data of each area on each clamping jaw between each moment and the previous moment is obtained and normalized to serve as the degree of pressure change of each area on each clamping jaw at each moment.

5. The five-axis loading and unloading robot according to claim 1, characterized in that: The method for obtaining the deformation degree of the workpiece includes: Normalize the relative force concentration of each area on each gripper at each moment, and calculate the product of the normalized result and the pressure change deviation as the first product; The maximum value of the first product corresponding to all areas on all jaws at each moment is selected as the deformation degree of the workpiece at each moment.

6. The five-axis loading and unloading robot according to claim 1, characterized in that: The method for obtaining the abnormal degree of pressure fluctuation includes: Obtain the extreme value of the pressure data of each area on each gripper at all times within the domain range of each moment, obtain the mean difference between all adjacent extreme values ​​at corresponding moments, and perform negative correlation mapping as the pressure fluctuation frequency of each area on each gripper; The relative force concentration degree of each area on each clamp at each moment is normalized, and the product of the normalized result and the pressure fluctuation frequency of all areas on all clamps at each moment is calculated as the pressure fluctuation abnormality degree at each moment.

7. The five-axis loading and unloading robot according to claim 1, characterized in that: The method for obtaining the deformation pressure threshold includes: The product of the maximum relative force concentration, the average pressure data and the preset protection coefficient in all areas of all grippers at the reference moment within the neighborhood of the real-time moment is obtained as the deformation pressure threshold at the real-time moment.

8. A method for adaptively adjusting the clamping force of a five-axis loading and unloading robot's mechanical claws, characterized in that: The method comprises: Obtain pressure data of different areas on each gripper when the gripper grips the workpiece at each moment; According to the pressure data distribution of different areas on each jaw at each moment, the relative force concentration of each area on each jaw at each moment is obtained; according to the pressure data change trend of each area on each jaw at different moments, the pressure change deviation degree of each area on each jaw at each moment is obtained; The degree of workpiece deformation at each moment is obtained based on the relative force concentration in different areas of different jaws at each moment and the degree of pressure change deviation. The degree of pressure fluctuation anomaly at each moment is obtained based on the relative force concentration in different areas of different jaws at each moment and the fluctuation characteristics of pressure data at different moments in the corresponding areas. The preset initial clamping force is adjusted based on the degree of abnormal pressure fluctuation at the real time, the degree of workpiece deformation at different times within the corresponding neighborhood, and the pressure data distribution of all areas on all clamping jaws to obtain the corrected clamping force at the next moment; The method for obtaining the corrected clamping force includes: According to the pressure data distribution of all areas on all jaws at each moment, the relative force concentration of each area on each jaw at each moment is obtained; If there is a time within the neighborhood of the real-time moment where the workpiece deformation degree is greater than or equal to the preset degree threshold, the maximum value at the corresponding time is used as the reference time, and the deformation pressure threshold at the real-time moment is obtained based on the relative force concentration and pressure data of all areas on all grippers at the reference time; The preset initial clamping force is adjusted according to the real-time deformation pressure threshold, the relative force concentration in all areas of all clamping jaws at the real-time moment, and the abnormal pressure fluctuation to obtain the corrected clamping force at the next moment; If there is no workpiece deformation degree greater than or equal to the preset degree threshold at a time within the neighborhood of the real time, the product of the positive integer 1 and the abnormal degree of pressure fluctuation at the real time is calculated as the adjustment weight; the product between the adjustment weight and the preset initial clamping force is obtained as the corrected clamping force at the next time; The preset initial clamping force is adjusted according to the deformation pressure threshold at the real time, the relative force concentration in all areas of all clamping jaws at the real time, and the abnormal pressure fluctuation to obtain the corrected clamping force at the next moment, including: Obtaining the ratio between the deformation pressure threshold at real time and the maximum relative force concentration in all areas of all jaws as the upper limit of the clamping force adjustment at real time; The difference between the clamping force adjustment upper limit at the real time and the preset initial clamping force is obtained as the first difference; the product of the first difference and the degree of pressure fluctuation abnormality at the real time is calculated, and the sum of the product result and the preset initial clamping force is calculated as the corrected clamping force at the next moment.

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