Five-axis feeding and discharging robot and gripper clamping force self-adaptive adjusting method

Abstract

The invention relates to the technical field of mechanical claws, in particular to a five-axis feeding and discharging robot and a mechanical claw clamping force self-adaptive adjusting method. According to the method, pressure data distribution of different areas on each clamping jaw at different moments is analyzed, the relative stress concentration degree and the pressure change deviation degree of each area on each clamping jaw at each moment are obtained, and the workpiece deformation degree at each moment is obtained; according to the relative stress concentration degrees of different areas on different clamping jaws at each moment and the fluctuation characteristics of the pressure data at different moments in the corresponding areas, the pressure fluctuation abnormal degree at each moment is obtained; and the preset initial clamping force is adjusted according to the pressure fluctuation abnormal degree at the real-time moment, the workpiece deformation degrees at different moments in the corresponding neighborhood range and the pressure data distribution of all the areas on all the clamping jaws, and the corrected clamping force at the next moment is obtained. The clamping force is accurately adjusted through self-adaptive adjustment of the mechanical claw, and the stability of the clamping claw in the grabbing process is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical claws, and particularly relates 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 an efficient automated device. During the process of machining workpieces, its core advantage lies in improving machining consistency through multi-angle collaborative operations. Since the surface of the workpiece has uneven textures when it is not fully machined, the robot is equipped with a vision recognition and force control system, which can adjust the grasping force and path to avoid scratching. Therefore, it is necessary to analyze the clamping force.

[0003] In the prior art, the clamping force of the mechanical claw is determined by program presetting to clamp the workpiece. However, when dealing with workpieces of different shapes or surface characteristics, the program preset clamping force may have the risk of excessive clamping force causing deformation or unstable clamping, with low efficiency and difficulty in adapting 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 adaptive adjustment effect of the clamping force 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 specific technical solutions adopted are as follows:

[0005] The present invention proposes a five-axis loading and unloading robot, which includes a robot body, a controller, and a pressure detector signal-connected to the controller. The pressure detector is used to detect the pressure data of different regions on each claw when the mechanical claw of the robot grabs the workpiece. The control method of the controller includes:

[0006] Obtain the pressure data of different regions on each claw when the mechanical claw grabs the workpiece at each moment;

[0007] According to the pressure data distribution of different regions on each claw at each moment, obtain the relative force concentration degree of each region on each claw at each moment; according to the change trend of the pressure data of each region on each claw at different moments, obtain the pressure change deviation degree of each region on each claw at each moment.

[0008] According to the relative force concentration degree of different regions on different claws at each moment and the pressure change deviation degree, obtain the deformation degree of the workpiece at each moment; according to the relative force concentration degree of different regions on different claws at each moment and the fluctuation characteristics of the pressure data of the corresponding regions at different moments, obtain the abnormal degree of pressure fluctuation at each moment.

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

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

[0011] For any moment, obtain the fluctuation degree of the pressure data of all regions on each jaw as the pressure fluctuation degree of each jaw.

[0012] Normalize the pressure data of each region on each jaw at each moment, and calculate the product of the normalization result and the pressure fluctuation degree as the relative force concentration degree of each region on each jaw at each moment.

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

[0014] According to the pressure data change trend of each region on each jaw at different moments, obtain the pressure change degree of each region on each jaw at each moment.

[0015] Obtain the average value of the pressure change degrees of each region on each jaw at all moments within the neighborhood range of each moment as the pressure change base value of each region on each jaw at each moment.

[0016] Obtain the difference between the pressure change base value and the pressure change degree of each region on each jaw at each moment. If the difference is greater than the preset difference threshold, take the corresponding difference as the pressure change deviation degree of each region on each jaw at each moment; if the difference is less than the preset difference threshold, take the corresponding preset difference threshold as the pressure change deviation degree of each region on each jaw at each moment.

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

[0018] Obtain the difference between the pressure data of each region on each jaw between each moment and the previous moment, and normalize it as the pressure change degree of each region on each jaw at each moment.

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

[0020] Normalize the relative force concentration degree of each region on each jaw at each moment, and calculate the product of the normalization result and the pressure change deviation degree as the first product.

[0021] Select the maximum value of the first product corresponding to all regions on all jaws at each moment as the workpiece deformation degree at each moment.

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

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

[0024] Normalize the relative force concentration degree of each area on each gripper at each moment, and calculate the cumulative product value of the corresponding normalized results and the pressure fluctuation frequency of all areas on all grippers at each moment as the abnormal degree of pressure fluctuation at each moment.

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

[0026] According to the pressure data distribution of all areas on all grippers at each moment, obtain the relative force concentration degree of each area on each gripper at each moment;

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

[0028] Adjust the preset initial clamping force according to the deformation pressure threshold at the real-time moment, the relative force concentration degree of all areas on all grippers at the real-time moment, and the abnormal degree of pressure fluctuation to obtain the corrected clamping force at the next moment;

[0029] If there is no moment within the neighborhood range 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 abnormal degree of pressure fluctuation 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.

[0030] Further, the adjusting the preset initial clamping force according to the deformation pressure threshold at the real-time moment, the relative force concentration degree of all areas on all grippers at the real-time moment, and the abnormal degree of pressure fluctuation to obtain the corrected clamping force at the next moment includes:

[0031] Obtain the ratio between the deformation pressure threshold at the real-time moment and the maximum value of the relative force concentration degree of all areas on all grippers as the upper limit of the clamping force adjustment at the real-time moment;

[0032] Obtain the difference between the upper limit of the clamping force adjustment at the real-time moment and the preset initial clamping force as the first difference; calculate the product of the first difference and the abnormal degree of the pressure fluctuation at the real-time moment, and calculate the sum of the product result and the preset initial clamping force as the corrected clamping force at the next moment.

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

[0034] Obtain the product of the maximum relative force concentration degree, the average pressure data, and the preset protection coefficient in all regions of all jaws corresponding to the reference moment within the neighborhood range at the real-time moment 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 the mechanical claw of a five-axis loading and unloading robot, and the method includes:

[0036] Obtain the pressure data of different regions on each jaw when the mechanical claw grabs the workpiece at each moment;

[0037] According to the pressure data distribution of different regions on each jaw at each moment, obtain the relative force concentration degree of each region on each jaw at each moment; according to the change trend of the pressure data of each region on each jaw at different moments, obtain the deviation degree of the pressure change of each region on each jaw at each moment.

[0038] According to the relative force concentration degree of different regions on different jaws at each moment and the deviation degree of the pressure change, obtain the workpiece deformation degree at each moment; according to the relative force concentration degree of different regions on different jaws at each moment and the fluctuation characteristics of the pressure data of the corresponding regions at different moments, obtain the abnormal degree of the pressure fluctuation at each moment.

[0039] Adjust the preset initial clamping force according to the abnormal degree of the pressure fluctuation at the real-time moment, the workpiece deformation degree of different moments within the corresponding neighborhood range, and the pressure data distribution of all regions of all jaws to obtain the corrected clamping force at the next moment.

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

[0041] According to the pressure data distribution of different regions on each gripper at each moment, the present invention obtains the relative force concentration degree of each region on each gripper at each moment, identifies the force degree of the gripper and each region, which helps to understand the pressure distribution; according to the pressure data change trend of each region on each gripper at different moments, the present invention obtains the pressure change deviation degree of each region on each gripper at each moment, and dynamically analyzes the pressure change characteristics of each region; according to the relative force concentration degree of different regions on different grippers at each moment and the pressure change deviation degree, the present invention obtains the workpiece deformation degree at each moment, and more accurately analyzes the workpiece deformation degree by considering the static pressure concentration distribution and dynamic change anomalies; according to the relative force concentration degree of different regions on different grippers at each moment and the fluctuation characteristics of the pressure data at different moments in the corresponding region, the present invention obtains the pressure fluctuation anomaly degree at each moment, and more accurately quantifies and analyzes the dynamic change characteristics of the pressure data of each region of the gripper; according to the pressure fluctuation anomaly degree at the real-time moment, the workpiece deformation degree at different moments within the corresponding neighborhood range, and the pressure data distribution of all regions on all grippers, the present invention adjusts the preset initial clamping force to obtain the corrected clamping force at the next moment. The present invention accurately adjusts the clamping force through the adaptive adjustment of the mechanical gripper, improving the stability in the process of gripper grasping. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to these drawings.

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

[0044] Figure 2 It is a flowchart of a control method provided by an embodiment of the present invention;

[0045] Figure 3 It is a flowchart of a method for obtaining the pressure change deviation degree provided by an embodiment of the present invention;

[0046] Figure 4 It is a flowchart of a method for obtaining the corrected clamping force provided by an embodiment of the present invention.

[0047] Figure 1Among them, 1 is the active axis responsible for the transversal movement control of the robotic arm; 2 is the active axis responsible for the transversal movement of the robotic arm; 3 is the active axis responsible for the transversal movement of the pallet; 4 is the active axis responsible for the up-and-down movement of the robotic arm; 5 is the active axis responsible for the rotation of the robotic arm; 6 is the pallet for storing workpieces; 7 is the electrical cabinet responsible for providing power to the five-axis loading and unloading robot and controlling the five-axis loading and unloading robot; 8 is the robotic gripper. Detailed implementation manners

[0048] In order to further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation manners, structures, features, and effects of a five-axis loading and unloading robot and a method for adaptively adjusting the clamping force of a robotic gripper proposed according to the present invention. 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.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs.

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

[0051] One embodiment of the present invention proposes a five-axis loading and unloading robot, including a robot body, and the robot body includes a structure referring to Figure 1 , which shows a schematic structural diagram of a five-axis loading and unloading robot: active axes 1 - 5, pallet 6, electrical cabinet 7, robotic gripper 8; through the active axes 1 - 5, the robotic gripper 8 is moved to the pallet 6 to grab and clamp the blank workpiece, the robotic arm is rotated through the active axis 5, and the blank workpiece is placed in the processing area of the numerical control processing equipment. After processing, the finished workpiece is grabbed and clamped and placed in the finished product collection area to complete the loading and unloading operation of the workpiece; it also includes a controller, and a pressure detector signal-connected to the controller. The pressure detector is used to detect the pressure data of different regions on each gripper when the robotic gripper of the robot clamps the workpiece. For the control method of the controller, please refer to Figure 2 , which shows a flowchart of a control method provided by one embodiment of the present invention, specifically including:

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

[0053] In an embodiment of the present invention, in order to avoid excessive or insufficient clamping force during grasping, which may cause deformation of the workpiece, it is necessary to analyze the pressure during clamping. First, a pneumatically driven mechanical claw is used to grasp workpieces such as blank parts and finished parts. Each contact surface between the clamping claws of the mechanical claw and the workpiece is longitudinally and evenly divided into multiple regions. In the present invention, it is divided into 4 regions. A PVDF piezoelectric film sensor is arranged on the silicone gasket in each region to obtain pressure data during the process of the mechanical claw grasping the workpiece, and obtain the pressure data of different regions on each clamping claw when the mechanical claw grasps the workpiece at each moment. It should be noted that in an embodiment of the present invention, the workpiece to be analyzed is an aluminum product. Each clamping claw grasps the workpiece with a preset initial clamping force of 2N, and at a frequency of 1kHz, that is, every 0.001 seconds, obtain the pressure values of different regions on each clamping claw when the mechanical claw grasps the workpiece at each moment; in other embodiments of the present invention, the preset initial clamping force and frequency can be specifically set according to specific situations, which will not be limited and elaborated here.

[0054] Step S2: According to the pressure data distribution of different regions on each clamping claw at each moment, obtain the relative force concentration degree of each region on each clamping claw at each moment; according to the pressure data change trend of each region on each clamping claw at different moments, obtain the pressure change deviation degree of each region on each clamping claw at each moment.

[0055] During the grasping process of the five-axis loading and unloading robot, since the workpiece is not fully processed, there are casting residues or original concave and convex textures before processing on the surface. The protruding areas are the first to contact and bear the concentrated pressure, while the pressure in the concave areas is significantly reduced due to incomplete fitting and the force is smaller. Therefore, by analyzing the pressure data distribution of different regions on each clamping claw, the relative force concentration degree of different regions can be more clearly understood; according to the pressure data distribution of different regions on each clamping claw at each moment, obtain the relative force concentration degree of each region on each clamping claw at each moment.

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

[0057] For any moment, obtain the fluctuation degree of the pressure data of all regions on each clamping claw as the pressure fluctuation degree of each clamping claw;

[0058] Normalize the pressure data of each region on each clamping claw at each moment, and calculate the product of the normalization result and the pressure fluctuation degree as the relative force concentration degree of each region on each clamping claw at each moment.

[0059] In an 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 represents the relative stress concentration degree of the b-th area on the a-th jaw; C a represents the degree of fluctuation of the pressure data of all areas on the a-th jaw, that is, the pressure fluctuation degree; B a,b represents the pressure data of the b-th area on the a-th jaw; B a represents the sum of the pressure data of all areas on the a-th jaw.

[0062] In the formula of the relative stress concentration degree, represents the value of the pressure data of the b-th area on the a-th jaw divided by the sum of the pressure data of all areas, that is, normalizing the pressure data of each area on each jaw at each moment. The larger the pressure data of the b-th area on the a-th jaw, the more the force on the b-th area on the a-th jaw is compared with the force on other areas, and the greater the relative stress concentration degree of the b-th area on the a-th jaw; the greater the degree of fluctuation of the pressure data of all areas on the a-th jaw, the more uneven the force distribution on the corresponding jaw, the more likely there is a bulge, and the greater the possibility of stress concentration in the area, and the greater the relative stress concentration degree.

[0063] It should be noted that in an embodiment of the present invention, the degree of fluctuation can be represented 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 represented by calculating the standard deviation or range. The specific means are well-known technical means to those skilled in the art and will not be limited and elaborated here.

[0064] When the jaw is too tight, the pressure will significantly exceed the critical point of workpiece deformation, resulting in plastic deformation; the smaller the contact area between the jaw and the workpiece, the greater the stress concentration effect, and the more it enters the plastic stage of the workpiece. As the clamping process progresses, the pressure data of the jaw first increases. When the pressure reaches the elastic limit of the workpiece, the workpiece's ability to resist deformation decreases, resulting in a slowdown or flattening of the pressure growth rate, and the greater the degree of deviation of the pressure change; therefore, according to the pressure data change trend of each area on each jaw at different times, the degree of deviation of the pressure change of each area on each jaw at each moment is obtained.

[0065] Preferably, in an embodiment of the present invention, for the method of obtaining the degree of deviation of the pressure change, please refer to Figure 3 , which shows a flowchart of a method for obtaining the degree of deviation of the pressure change provided by an embodiment of the present invention, including:

[0066] Step S301: According to the pressure data change trend of each area on each jaw at different times, obtain the degree of pressure change of each area on each jaw at each moment.

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

[0068] Obtain the difference between the pressure data of each area on each gripper between each moment and the previous moment, and perform normalization, which is used as the degree of pressure change of each area on each gripper at each moment.

[0069] Among them, the smaller the difference is, the slower the growth rate of the pressure data is, and the more likely it is affected by deformation.

[0070] Step S302: Obtain the average value of the degree of pressure change of each area on each gripper at all moments within the neighborhood range of each moment, which is used as the pressure change base value of each area on each gripper at each moment.

[0071] Quantify the degree of pressure change corresponding to all moments within the neighborhood range by taking the average value, which reflects the overall pressure level and provides a benchmark for subsequent data comparison.

[0072] It should be noted that, in an embodiment of the present invention, the size of the neighborhood range is a range composed of a preset number of historical moments based on each moment, where the preset number is 50; in other embodiments of the present invention, the size of the neighborhood range can be specifically set according to specific circumstances, and no limitation and elaboration are made here.

[0073] Step S303: Obtain the difference between the pressure change base value and the degree of pressure change of 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 pressure change deviation of 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 pressure change deviation of each area on each gripper at each moment.

[0074] In an embodiment of the present invention, the formula for the degree of pressure change deviation 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 represents the degree of pressure change deviation of the bth area on the ath gripper at the cth moment; E c,a,b represents the pressure change base value of the bth area on the ath gripper at the cth moment; F c,a,b represents the degree of pressure change 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 pressure change deviation, Ec,a,b -F c,a,b It represents the difference between the base value of the pressure change and the degree of pressure change in the b-th area of the a-th jaw at the c-th moment. The larger the difference, the greater the base value of the pressure change relative to the degree of pressure change, the slower the pressure increase or the tendency to stabilize, the decrease in the ability of the workpiece to resist deformation, and the more likely a large pressure deviation will occur; if the base value of the pressure change in the b-th area of the a-th jaw at the c-th moment is much smaller than the degree of pressure change, the smaller the difference, the smaller the base value of the pressure change relative to the degree of pressure change, the more the pressure shows an increasing trend, and the smaller the deviation degree of the pressure change.

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

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

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

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

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

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

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

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

[0086] where Gc represents the deformation degree of the workpiece at the c-th moment; A c,a,b represents the relative force concentration degree of the b-th area on the a-th gripper at the c-th moment; D c,a,b represents the deviation degree of the pressure change in the b-th area on the a-th gripper at the c-th moment; norm() represents the normalization function; MAX() represents the maximum value function.

[0087] In the formula for the deformation degree of the workpiece, the greater the relative force concentration degree of the b-th area on the a-th gripper at the c-th moment, the greater the force on the corresponding gripper area, and the more likely it is that the clamping force is too large; the greater the deviation degree of the pressure change in the b-th area on the a-th gripper at the c-th moment, the more obvious the pressure change, and the more likely it is that deformation has occurred, and the greater the deformation degree of the workpiece.

[0088] When the clamping force is relatively small, the workpiece will slide and fall due to gravity, and the dynamic friction between the workpiece and the gripper will mutate. The greater the fluctuation characteristics of the pressure data at different moments, the greater the abnormal degree of the pressure fluctuation. According to the relative force concentration degree of different areas on different grippers at each moment, and the fluctuation characteristics of the pressure data at different moments in the corresponding areas, the abnormal degree of the pressure fluctuation at each moment is obtained.

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

[0090] Obtain the extreme values of the pressure data in each area of each gripper at all moments within the domain range of each moment, obtain the average difference of the corresponding moments between all adjacent extreme values, and perform a negative correlation mapping to obtain the pressure fluctuation frequency of each area of each gripper;

[0091] Normalize the relative force concentration degree of each area of each gripper at each moment, and calculate the cumulative product value of the corresponding normalization results and the pressure fluctuation frequency of all areas of all grippers at each moment as the abnormal degree of the pressure fluctuation at each moment.

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

[0093]

[0094] where, M c represents the abnormal degree of the pressure fluctuation at the c-th moment; Q represents the number of grippers; P represents the number of areas on each gripper; A c,a,b represents the relative force concentration degree of the b-th area on the a-th gripper at the c-th moment; N c,a,b represents the pressure fluctuation frequency of the b-th area on the a-th gripper at the c-th moment; softmax() represents the normalization function.

[0095] In the formula for the abnormal degree of pressure fluctuation, the greater the relative force concentration degree, the greater the pressure fluctuation frequency, the more it can reflect that the area with greater force generates more frequent fluctuations, and the greater the abnormal degree of pressure fluctuation.

[0096] It should be noted that in an embodiment of the present invention, the method for obtaining the extreme value is as follows: If there is any moment when the corresponding pressure data is greater than or less than the pressure data of the adjacent front and rear moments, the pressure data at the corresponding moment is used as the extreme value; in other embodiments of the present invention, the extreme value can also be obtained by the Newton method, and the specific means are well-known technical means 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 moment, the workpiece deformation degree at different moments within the corresponding neighborhood range, and the pressure data distribution of all areas on all jaws, and obtain the corrected clamping force at the next moment.

[0098] Pressure fluctuation reflects the contact stability. The greater the pressure fluctuation, the smaller the contact stability, and the more likely it is necessary to adjust the corrected clamping force at the next moment; deformation is an embodiment of the workpiece's tolerance, and the degree of workpiece deformation is reflected by the workpiece deformation degree. The greater the workpiece deformation degree, the greater the clamping force of the jaws, and the more it is necessary to adjust the corrected clamping force at the next moment; therefore, by analyzing the abnormal degree of pressure fluctuation, the workpiece deformation degree, and the pressure data, it is helpful to understand the pressure change situation of the jaws and the deformation state of the workpiece, and more comprehensively and accurately evaluate the corrected clamping force at the next moment.

[0099] Preferably, in an embodiment of the present invention, for the method of obtaining the corrected clamping force, please refer to Figure 4 , which shows a flowchart of a method for obtaining a corrected clamping force provided by an embodiment of the present invention, including:

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

[0101] The relative force concentration degree reflects the force concentration situation of the areas on the jaws, and is helpful to understand the pressure intensity characteristics when applying the clamping force to the workpiece.

[0102] Step S402: If there is a moment within the neighborhood range of the real-time moment when the workpiece deformation degree is greater than or equal to the preset degree threshold, take the maximum value at the corresponding moment as the reference moment, and obtain the deformation pressure threshold at the real-time moment according to the relative force concentration degree and pressure data of all areas on all jaws at the reference moment.

[0103] The degree of workpiece deformation reflects the possibility of workpiece deformation. The greater the degree of workpiece deformation, 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 an embodiment of the present invention, the size of the preset degree threshold is 0.5, that is, the moment when the degree of workpiece deformation is greater than or equal to 0.5 is selected, and the maximum value in the corresponding moments is used as the reference moment. In other embodiments of the present invention, the size of the preset degree threshold can be specifically set according to specific circumstances, which will not be limited and elaborated here.

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

[0105] Obtain the product of the maximum value of the relative force concentration degree, the average pressure data, and the preset protection coefficient in all regions on all jaws corresponding to the reference moment within the neighborhood range of the real-time moment, as the deformation pressure threshold at the real-time moment.

[0106] It should be noted that in the embodiments of the present invention, the average pressure data is the average value of the pressure data on all regions of all jaws at the real-time moment, that is, the average pressure data.

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

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

[0109] It should be noted that in an embodiment of the present invention, adjusting the preset initial clamping force according to the deformation pressure threshold at the real-time moment, the relative force concentration degree in all regions on all jaws at the real-time moment, and the abnormal degree of pressure fluctuation to obtain the corrected clamping force at the next moment includes:

[0110] Obtain the ratio between the deformation pressure threshold at the real-time moment and the maximum value of the relative force concentration degree in all regions on all jaws, as the upper limit of clamping force adjustment at the real-time moment;

[0111] Obtain the difference between the upper limit of clamping force adjustment at the real-time moment and the preset initial clamping force, as the first difference; calculate the product of the first difference and the abnormal degree of pressure fluctuation at the real-time moment, and calculate the sum of the product result and the preset initial clamping force, as the corrected clamping force at the next moment.

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

[0113] R i+1 = S + (T i - S) × M i ;

[0114]

[0115] Wherein, R i+1 represents the corrected clamping force at the next moment i + 1; S represents the preset initial clamping force; M i represents the degree of abnormal pressure fluctuation at the real-time moment i; T i represents the upper limit of 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 value of the relative force concentration degree in all regions on all jaws at the real-time moment.

[0116] In the formula of the corrected clamping force, the greater the maximum value of the relative force concentration degree, the greater the force on the workpiece during clamping, and the more necessary it is to reduce the clamping force to avoid excessive force on the region. To avoid deformation of the workpiece, based on the obtained deformation pressure threshold analysis, the greater the deformation pressure threshold, the greater the tolerable clamping force, and the greater the upper limit of clamping force adjustment; (T i - S) represents the difference between the upper limit of clamping force adjustment and the preset initial clamping force at the real-time moment, as the first difference. The greater the first difference, the greater the upper limit of clamping force adjustment is greater than the preset initial clamping force, and the greater the degree of increasing the clamping force. If the first difference is smaller, it is closer to the upper limit of clamping force adjustment, and the degree of increasing the clamping force is smaller.

[0117] For the existence of the deformation pressure threshold, in order to avoid excessive clamping force, the adjustment of the preset initial clamping force should not be greater than the upper limit of clamping force adjustment. Obtain the difference between the upper limit of clamping force adjustment and the preset initial clamping force at the real-time moment as the first difference. If the ratio of the preset initial clamping force to the upper limit of clamping force adjustment is greater, the first difference is smaller, and in the negative direction, the more the clamping force is reduced, and the smaller the corrected clamping force at the next moment.

[0118] Step S404: If there is no workpiece deformation degree greater than or equal to the preset degree threshold within the neighborhood range of the real-time moment, calculate the product of the positive integer 1 and the degree of abnormal pressure fluctuation 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 an embodiment of the present invention, the formula of the corrected clamping force is expressed as:

[0120] R i+1 = S × (1 + M i );

[0121] Wherein, R i+1Denote the corrected clamping force at the next moment \(i + 1\); \(S\) denotes the preset initial clamping force; \(M\) i Denote the abnormal degree of pressure fluctuation at the real-time moment \(i\); \(T\) i Denote the upper limit of clamping force adjustment at the real-time moment \(i\).

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

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

[0124] It should be noted that when obtaining the adjusted corrected clamping force, considering that when the clamping force reaches the adjustment upper limit, there may be a situation where the gravity cannot be offset and the robotic gripper cannot grasp the workpiece. If the difference between the corrected clamping force and the preset initial clamping force is less than the preset difference threshold, where the size of the preset difference threshold can be set according to specific situations. For example, if the preset difference threshold is 0.01, the smaller the corresponding adjustment amplitude, the robot cannot perform adaptive adjustment, and an alarm needs to be processed to check whether the quality of the workpiece is qualified. For qualified workpieces, the silicone gasket of the robotic gripper can be replaced to improve the stability of the robotic gripper for workpiece grasping.

[0125] In summary, the present invention analyzes the pressure data distribution of different regions on each gripper at different moments, obtains the relative force concentration degree and the degree of deviation of pressure change of each region on each gripper at each moment, and obtains the deformation degree of the workpiece at each moment; according to the relative force concentration degree of different regions on different grippers at each moment, and the fluctuation characteristics of the pressure data of the corresponding regions at different moments, obtains the abnormal degree of pressure fluctuation at each moment; adjusts the preset initial clamping force according to the abnormal degree of pressure fluctuation at the real-time moment, the deformation degree of the workpiece at different moments within the corresponding neighborhood range, and the pressure data distribution of all regions on all grippers, to obtain the corrected clamping force at the next moment. The present invention accurately adjusts the clamping force through the adaptive adjustment of the robotic gripper, improving the stability during the gripper grasping process.

[0126] The present invention also proposes a method for adaptive adjustment of the clamping force of the robotic gripper of a five-axis loading and unloading robot, the method comprising:

[0127] Obtain the pressure data of different regions on each gripper of the robotic gripper for gripping the workpiece at each moment;

[0128] According to the pressure data distribution of different regions on each gripper at each moment, obtain the relative force concentration degree of each region on each gripper at each moment; according to the pressure data change trend of each region on each gripper at different moments, obtain the pressure change deviation degree of each region on each gripper at each moment.

[0129] According to the relative force concentration degree of different regions on different grippers at each moment, and the pressure change deviation degree, obtain the workpiece deformation degree at each moment; according to the relative force concentration degree of different regions on different grippers at each moment, and the fluctuation characteristics of the pressure data of the corresponding regions at different moments, obtain the abnormal degree of pressure fluctuation at each moment.

[0130] Adjust the preset initial clamping force according to the abnormal degree of pressure fluctuation at the real-time moment, the workpiece deformation degree at different moments within the corresponding neighborhood range, and the pressure data distribution of all regions on all grippers, to obtain the corrected clamping force at the next moment.

[0131] It should be understood that a method for adaptively adjusting 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, so it has the same steps and beneficial effects as the control method adopted, run or implemented by the stored application program.

[0132] It should be noted that the above-mentioned sequence of the embodiments of the present invention is only for description and does not represent the advantages and disadvantages of the embodiments. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

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

Claims

1. A five-axis loading and unloading robot, comprising a robot body, characterized in that, It further includes a controller, and a pressure detector signal - connected to the controller. The pressure detector is used to detect the pressure data of different regions on each jaw when the robotic gripper grabs a workpiece. The control method of the controller includes: Obtaining the pressure data of different regions on each jaw when the robotic gripper grabs a workpiece at each moment; According to the pressure data distribution of different regions on each jaw at each moment, obtaining the relative force - concentration degree of each region on each jaw at each moment; according to the pressure data change trend of each region on each jaw at different moments, obtaining the pressure change deviation degree of each region on each jaw at each moment; According to the relative force - concentration degree of different regions on different jaws at each moment, and the pressure change deviation degree, obtaining the workpiece deformation degree at each moment; according to the relative force - concentration degree of different regions on different jaws at each moment, and the fluctuation characteristics of the pressure data of corresponding regions at different moments, obtaining the abnormal degree of pressure fluctuation at each moment; Adjusting the preset initial clamping force according to the abnormal degree of pressure fluctuation at the real - time moment, the workpiece deformation degree of different moments within the corresponding neighborhood range, and the pressure data distribution of all regions on all jaws to obtain the corrected clamping force at the next moment.

2. The five-axis loading and unloading robot according to claim 1, wherein The method for obtaining the relative force - concentration degree includes: For any moment, obtaining the fluctuation degree of the pressure data of all regions on each jaw as the pressure fluctuation degree of each jaw; Normalizing the pressure data of each region on each jaw at each moment, and calculating the product of the normalization result and the pressure fluctuation degree as the relative force - concentration degree of each region on each jaw at each moment.

3. A 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 region on each jaw at different moments, obtaining the pressure change degree of each region on each jaw at each moment; Obtaining the average value of the pressure change degrees of each region on each jaw within the neighborhood range of each moment as the pressure change base value of each region on each jaw at each moment; Obtaining the difference between the pressure change base value and the pressure change degree of each region on each jaw at each moment. If the difference is greater than the preset difference threshold, taking the corresponding difference as the pressure change deviation degree of each region on each jaw at each moment; if the difference is less than the preset difference threshold, taking the corresponding preset difference threshold as the pressure change deviation degree of each region on each jaw at each moment.

4. A five-axis loading and unloading robot according to claim 3, wherein, The method for obtaining the pressure change degree includes: Obtaining the difference between the pressure data of each region on each jaw between each moment and the previous moment, and normalizing it as the pressure change degree of each region on each jaw at each moment.

5. A five-axis loading and unloading robot according to claim 1, characterized in that, The method for obtaining the workpiece deformation degree includes: Normalizing the relative force - concentration degree of each region on each jaw at each moment, and calculating the product of the normalization result and the pressure change deviation degree as the first product; Selecting the maximum value of the first product corresponding to all regions on all jaws at each moment as the workpiece deformation degree at each moment.

6. A five-axis loading and unloading robot according to claim 1, wherein, The method for obtaining the abnormal degree of pressure fluctuation includes: Obtain the extreme values in the pressure data of each area on each jaw at all times within the domain at each moment, obtain the mean difference of the corresponding times between all adjacent extreme values, and perform a negative correlation mapping to obtain the pressure fluctuation frequency of each area on each jaw. Normalize the relative force concentration degree of each area on each jaw at each moment, and calculate the cumulative product value of the corresponding normalized results and the pressure fluctuation frequency of all areas on all jaws at each moment as the pressure fluctuation anomaly degree at each moment.

7. A five-axis loading and unloading robot according to claim 1, characterized in that, The method for obtaining the corrected clamping force includes: Obtain the relative force concentration degree of each area on each jaw at each moment according to the pressure data distribution of all areas on all jaws at each moment. If the workpiece deformation degree at a moment within the neighborhood range of the real-time moment is greater than or equal to the preset degree threshold, take the maximum value at the corresponding moment as the reference moment, and obtain the deformation pressure threshold at the real-time moment according to the relative force concentration degree and pressure data of all areas on all jaws at the reference moment. Adjust the preset initial clamping force according to the deformation pressure threshold at the real-time moment, the relative force concentration degree and the pressure fluctuation anomaly degree of all areas on all jaws at the real-time moment to obtain the corrected clamping force at the next moment. If there is no moment within the neighborhood range 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 anomaly 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.

8. A five-axis loading and unloading robot according to claim 7, characterized in that, The adjusting the preset initial clamping force according to the deformation pressure threshold at the real-time moment, the relative force concentration degree of all areas on all jaws at the real-time moment and the pressure fluctuation anomaly degree to obtain the corrected clamping force at the next moment includes: Obtain the ratio between the deformation pressure threshold at the real-time moment and the maximum value of the relative force concentration degree of all areas on all jaws as the clamping force adjustment upper limit at the real-time moment. Obtain the difference between the clamping force adjustment upper limit at the real-time moment and the preset initial clamping force as the first difference; calculate the product of the first difference and the pressure fluctuation anomaly degree at the real-time moment, and calculate the sum of the product result and the preset initial clamping force as the corrected clamping force at the next moment.

9. A five-axis loading and unloading robot according to claim 7, wherein, The method for obtaining the deformation pressure threshold includes: Obtain the product of the maximum value of the relative force concentration degree, the average pressure data and the preset protection coefficient of all areas on all jaws at the corresponding reference moment within the neighborhood range of the real-time moment as the deformation pressure threshold at the real-time moment.

10. A method for adaptively adjusting the clamping force of the mechanical claw of a five-axis loading and unloading robot, characterized in that, The method includes: Obtain the pressure data of different areas on each jaw when the robotic gripper grabs the workpiece at each moment. Obtain the relative force concentration degree of each area on each jaw at each moment according to the pressure data distribution of different areas on each jaw at each moment; obtain the pressure change deviation degree of each area on each jaw at each moment according to the pressure data change trend of each area on each jaw at different moments. Obtain the workpiece deformation degree at each moment according to the relative force concentration degree of different regions on different grippers and the deviation degree of pressure change at each moment; obtain the abnormal degree of pressure fluctuation at each moment according to the relative force concentration degree of different regions on different grippers and the fluctuation characteristics of pressure data at different moments within the corresponding regions. Adjust the preset initial clamping force according to the abnormal degree of pressure fluctuation at the real-time moment, the workpiece deformation degree at different moments within the corresponding neighborhood range, and the pressure data distribution of all regions on all grippers to obtain the corrected clamping force at the next moment.

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