Encircling type mechanical claw clamping control method and system based on stepping motor

Abstract

The invention discloses an encircling type mechanical claw clamping control method and system based on a stepping motor, and relates to the technical field of clamping control, and the method comprises the following steps: obtaining the clamping width of a target mechanical claw, dividing the target mechanical claw into a plurality of clamping candidate areas along the length direction of an object to be clamped, and collecting the surface structure feature data of each area; and according to the feature data and the distance between each region and the gravity center of the object, evaluating stability scores, arranging the stability scores in a descending order to form a clamping candidate region sequence, sequentially determining the maximum clamping force of each region, calculating the minimum clamping pressure of stable clamping, and comparing the minimum clamping pressure with the maximum clamping force to determine the region meeting the clamping condition, so that the clamping accuracy of the object is improved. And clamping is conducted at the minimum clamping pressure in the area meeting the conditions, the tightening step length of the stepping motor is set, the clamping pressure is dynamically adjusted according to vibration and slippage parameters in the transportation process, and therefore efficient and stable clamping control is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of clamping control, in particular to a ring type mechanical gripper clamping control method and system based on a stepping motor. BACKGROUND

[0002] Under the background of rapid development of modern automation and robot technology, electric gripper clamping systems are increasingly widely used in industrial manufacturing, material handling, and service robots. The clamping stability and accuracy of the electric gripper directly affect the processing quality and production efficiency of the workpiece. Traditional mechanical clamps often rely on pneumatic or hydraulic systems for clamping. Although these systems perform well in clamping force, they have many problems. First, the control of pneumatic and hydraulic systems is relatively complex, requiring complex air or hydraulic system support, which increases the cost and maintenance difficulty of the system. At the same time, due to the possibility of leakage in the working process of pneumatic and hydraulic systems, the clamping force is unstable, which can cause the workpiece to slip or fall during clamping, thereby affecting production efficiency and product quality.

[0003] With the continuous progress of stepping motor technology, electric gripper clamping systems based on stepping motor drive have gradually become a new emerging clamping solution. Stepping motors have good precise positioning ability and control response speed, and are suitable for clamping applications that require high precision and high stability. However, in actual application, how to accurately control the operation of the stepping motor and real-time feedback the clamping state is still a technical problem. Existing control methods often only rely on the set operating parameters, without effectively considering the errors and nonlinear factors that may exist in the actual operation of the motor, resulting in inaccurate judgment of the clamping state and affecting the clamping quality.

[0004] In the prior art, the publication number CN107498573A discloses an electric gripper clamping control method based on stepping motor drive and an electric gripper based on stepping motor drive, which specifically includes a method of clamping a workpiece according to the calculation of electromagnetic torque; or a method of calculating the difference between the theoretical running distance and the actual running distance of the motor, and comparing it with the set threshold to judge the clamping state of the electric gripper. The provided method can quickly control the clamping of the gripper to hold the workpiece, effectively improving the stability and accuracy of clamping. However, this scheme does not consider how to select the clamping area, which may result in uneven distribution of clamping force and affect the clamping effect. In addition, the method of difference between the theoretical and actual running distance only uses position error threshold to judge the clamping state, ignoring the subtle changes in the relative movement of the clamped object during the clamping process. Therefore, it is not possible to dynamically adjust the clamping effect according to the relative movement of the clamped object during the clamping process, resulting in a decrease in the accuracy and effectiveness of the clamping effect.

[0005] The above information disclosed in the background section is only for enhancing the understanding of the background of the present disclosure, and therefore it can include information that does not constitute prior art that is already known to those of ordinary skill in the art. SUMMARY

[0006] The purpose of the present application is to provide a stepping motor-based ring-type mechanical gripper clamping control method and system to solve the problems raised in the background.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical solutions: A stepping motor-based ring-type mechanical gripper clamping control method, the specific steps comprising: Obtaining the clamping width of the target ring-type mechanical gripper, based on the clamping width of the target ring-type mechanical gripper, dividing the object to be clamped into a plurality of clamping candidate areas along the length direction of the object to be clamped, and collecting surface structure feature data of each clamping candidate area; According to the surface structure feature data of each clamping candidate area, combining the distance between each clamping candidate area and the center of gravity of the object to be clamped, evaluating the stability score of each clamping candidate area, and based on the stability score of each clamping candidate area, forming a clamping candidate area sequence in descending order; Based on the order of the clamping candidate area sequence, the maximum clamping force that each clamping candidate area can withstand is determined in sequence, and based on the gravity of the object to be clamped, the minimum clamping pressure that ensures stable clamping at each clamping candidate area is calculated, and the minimum clamping pressure is compared with the maximum clamping force that can be Withstood, the final clamping position is determined; Clamping the object to be clamped at the clamping position with the minimum clamping pressure, setting the tightening step length of the stepping motor, and dynamically adjusting the minimum clamping pressure according to the vibration and slip parameters of the object to be clamped during transportation to complete the clamping control.

[0008] Further, the clamping width of the target ring-type mechanical gripper specifically refers to the clamping face width of the target ring-type mechanical gripper; Based on the clamping width of the target ring-type mechanical gripper, the object to be clamped is divided into a plurality of clamping candidate areas along the length direction of the object to be clamped, and the logic is as follows: a sliding window is set with the clamping width of the target ring-type mechanical gripper, the clamping width is the width of the sliding window, one end of the sliding window is set on one side of the edge of the object to be clamped in the length direction, the sliding window is controlled to move along the length direction of the object to be clamped by 2 unit lengths each time, and each time the sliding window is moved, the area where the sliding window is located is recorded as a clamping candidate area, until the remaining length of the surface of the object to be clamped is less than the width of the sliding window after a certain movement, stop moving, and obtain a plurality of clamping candidate areas during the entire movement process; The surface structure feature data of each clamping candidate region specifically includes: the fluctuation degree of the surface of each clamping candidate region and the surface roughness of the clamping candidate region.

[0009] Further, the logic for evaluating the stability score of each clamping candidate region is: calculating the surface flatness coefficient of each clamping candidate region based on the surface structure feature data of each clamping candidate region, representing the clamping difficulty of the clamping candidate region according to the surface flatness coefficient, and comprehensively calculating the stability score of each clamping candidate region according to the surface flatness coefficient and the distance between each clamping candidate region and the gravity center of the object to be clamped, wherein the formula for calculating the surface flatness coefficient is: ; In the formula, is the surface flatness coefficient of the i-th clamping candidate region, is the maximum fluctuation difference normalized value of the i-th clamping candidate region, is the average roughness normalized value of the i-th clamping candidate region, and are the weight coefficients of the roughness and the maximum fluctuation difference of the clamping candidate region, respectively, wherein , and and are both greater than 0, and i is the index of the clamping candidate region; wherein the maximum fluctuation difference of the i-th clamping candidate region is specifically defined as the difference between the highest point and the lowest point on the surface of the i-th clamping candidate region, and the logic for obtaining the maximum fluctuation difference normalized value of the i-th clamping candidate region is: calculating the difference between the highest point and the lowest point of all clamping candidate regions, determining the maximum difference value, and normalizing the maximum fluctuation difference of each clamping candidate region by the maximum difference value, specifically by taking the ratio of the maximum fluctuation difference of each clamping candidate region to the maximum difference value as the maximum fluctuation difference normalized value; wherein the average roughness of the clamping candidate region is used to represent the fluctuation degree of the region, and the formula for calculating the average roughness normalized value of the i-th clamping candidate region is: ; In the formula, is the average roughness of the i-th clamping candidate region, is the maximum roughness of all clamping candidate regions, wherein the average roughness of the i-th clamping candidate region The specific acquisition method is: a plurality of detection sub-regions are randomly selected on the surface of the i-th clamping candidate region, and the average roughness of all detection sub-regions is calculated, and the average roughness is taken as the average roughness of the clamping candidate region. The formula for calculating the average roughness of all detection sub-regions is: ; In the formula, is the roughness of the j-th detection sub-region in the i-th clamping candidate region, where j is the index of the detection sub-region, , is the total number of randomly selected detection sub-regions on the surface of the clamping candidate region.

[0010] Further, the formula for calculating the stability score of each clamping candidate region is: ; In the formula, is the stability score of the i-th clamping candidate region, is the distance between the i-th clamping candidate region and the center of gravity of the object to be clamped, specifically the straight-line distance from the center of gravity of the i-th clamping candidate region to the center of gravity of the object to be clamped, is the maximum distance from the center of gravity of the object to be clamped among all clamping candidate regions; Based on the stability score of each clamping candidate region, each clamping candidate region is sorted in descending order to form a clamping candidate region sequence.

[0011] Further, the logic for determining the maximum clamping force that each clamping candidate region can withstand based on the material characteristics of each clamping candidate region is: a finite element model of each clamping candidate region is constructed, and through finite element analysis, the pressure that the deformation of each clamping candidate region of the object to be clamped reaches the maximum irreversible deformation is determined, which is taken as the maximum clamping force that the corresponding clamping candidate region can withstand. The formula for calculating the minimum clamping pressure for stable clamping based on the gravity of the object to be clamped is: ; In the formula, is the gravity of the object to be clamped, is the minimum clamping pressure of the clamping candidate region, is the friction coefficient of the clamping candidate region.

[0012] Further, In sequence of the sequence of the clamping candidate regions, the minimum clamping pressure of each clamping candidate region is compared with the maximum clamping force that can be borne to determine whether each clamping candidate region meets the clamping condition, and the first clamping candidate region meeting the clamping condition is the final clamping position, and the clamping condition is specifically that the product of the minimum clamping pressure of the clamping candidate region and the maximum adjustment range is less than the maximum clamping force that can be borne by the clamping candidate region, and the formula on which the clamping condition is specifically based is: ; In the formula, is the maximum adjustment range, is the maximum clamping force that can be borne by the clamping candidate region, wherein yz is greater than 1.

[0013] Further, according to the vibration and slip parameters of the object to be clamped in the transportation process, the minimum clamping pressure is dynamically adjusted, and the logic on which the dynamic adjustment of the minimum clamping pressure is specifically based is that the vibration parameter of the object to be clamped is specifically the vibration acceleration, the clamping pressure is increased by one tightening step through the stepping motor, the maximum vibration acceleration and the maximum slip distance in the current clamping state are detected, and it is determined whether the maximum vibration acceleration and the maximum slip distance fall within the corresponding safety interval, if both fall within the corresponding safety interval, the current clamping pressure is used for transportation, if both do not fall within the corresponding safety interval, the clamping pressure is increased by one tightening step through the stepping motor again on the basis of the current clamping pressure, and it is further determined whether the maximum vibration acceleration and the maximum slip distance both fall within the corresponding safety interval, and the iteration operation is sequentially performed until the determined clamping pressure is met.

[0014] The application also provides a step motor-based ring-type mechanical claw clamping control system for executing the step motor-based ring-type mechanical claw clamping control method described above, comprising: A clamping region planning module is configured to obtain the clamping width of a target ring-type mechanical claw, divide the object to be clamped into a plurality of clamping candidate regions along the length direction of the object to be clamped based on the clamping width of the target ring-type mechanical claw, and collect surface structure feature data of each clamping candidate region. A clamping force analysis module is configured to evaluate the stability score of each clamping candidate region according to the surface structure feature data of each clamping candidate region and the distance between each clamping candidate region and the center of gravity of the object to be clamped, and form a sequence of clamping candidate regions in descending order based on the stability score of each clamping candidate region. The clamping area replacement module is used for sequentially determining the maximum clamping force that can be borne by each clamping candidate area based on the sequence of the clamping candidate area sequence, and calculating the minimum clamping pressure that guarantees stable clamping at each clamping candidate area based on the gravity of the object to be clamped, and determining the final clamping position by comparing the minimum clamping pressure with the maximum clamping force that can be borne. The clamping force dynamic adjustment module is used for clamping the object to be clamped at the clamping position with the minimum clamping pressure, setting the tightening step length of the stepping motor, and dynamically adjusting the minimum clamping pressure according to the vibration and slip parameters of the object to be clamped in the transportation process to complete the clamping control.

[0015] Compared with the prior art, the beneficial effects of the present application are: Firstly, by obtaining the clamping width of the target ring-type mechanical claw, dividing a plurality of clamping candidate areas in the length direction of the object, and comprehensively evaluating the surface structure characteristics of each area, the area with the highest stability score is selected as the best clamping area, effectively improving the stability of clamping and reducing the risk of clamping failure. Secondly, in the clamping process, the maximum clamping force that can be borne is determined based on the material characteristics of the best clamping area, and after determining the maximum clamping force that can be borne by each clamping candidate area, the required minimum clamping pressure is calculated in combination with the gravity of the object to be clamped, further ensuring the stability of clamping, and more accurately controlling the clamping force, ensuring that the clamping force matches the gravity of the object in actual operation, avoiding the risk of object sliding due to insufficient clamping force, and the mechanism of dynamically adjusting the minimum clamping pressure enables the mechanical claw to respond to changes such as vibration and slip in the transportation process, significantly improving the robustness and adaptability of the overall grasping system, effectively preventing the object from slipping and being damaged, improving the safety of clamping, and also helping to maintain the stability of the object during transportation, thereby reducing the occurrence of accidents. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a whole method flowchart of the present application; Figure 2 It is a distance from the center of gravity of the object to be clamped-stability score fitting curve diagram; Figure 3 It is an average roughness normalized value-surface flatness coefficient fitting curve diagram; Figure 4 It is a maximum fluctuation difference normalized value-surface flatness coefficient corresponding relationship diagram; Figure 5 It is a whole system structure schematic diagram of the present application. DETAILED DESCRIPTION

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0018] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0019] Example: Please see Figures 1-4 The present invention provides a technical solution: A method for controlling a ring-shaped mechanical gripper based on a stepper motor, comprising the following steps: Step 1: Obtain the gripping width of the target gripping manipulator. Based on the gripping width of the target gripping manipulator, divide the object to be gripped into several gripping candidate regions along the length direction of the object to be gripped, and collect the surface structure feature data of each gripping candidate region.

[0020] The clamping width of the target encircling mechanical claw specifically refers to the clamping surface width of the target encircling mechanical claw; The specific method used to obtain the clamping width of the target encircling robotic gripper is as follows: use precision measuring tools such as calipers and micrometers to actually measure the robotic gripper. During the measurement, ensure that the clamping surface is in an unclamped state to avoid errors caused by deformation. If there is a 3D model of the robotic gripper, computer-aided design (CAD) software such as SolidWorks and AutoCAD can be used for measurement. In the software, directly select the clamping width of the target encircling robotic gripper for accurate measurement. The logic for dividing the object to be gripped into a plurality of gripping candidate regions according to the gripping width of the target ring-type gripper along the length direction of the object to be gripped is as follows: a sliding window is set according to the gripping width of the target ring-type gripper, the gripping width being the width of the sliding window, one end of the sliding window is set on one side of the edge in the length direction of the object to be gripped, the sliding window is controlled to move along the length direction of the object to be gripped by 2 unit lengths each time, each time the sliding window is moved, the region where the sliding window is located is recorded as a gripping candidate region, until the remaining length of the surface of the object to be gripped is less than the width of the sliding window after a certain movement, the movement is stopped, and a plurality of gripping candidate regions in the entire movement process are obtained, wherein the 2 unit lengths are specifically 2 cm. Surface structure feature data of each gripping candidate region is collected, and the surface structure feature data specifically includes: the undulation degree of the surface of each gripping candidate region and the surface roughness of the gripping candidate region. The method for obtaining the undulation degree of the surface of the gripping candidate region is as follows: the surface undulation degree reflects the overall shape change and height difference of the surface of the object, and is mainly determined by measuring the profile characteristics of the surface, a three-dimensional scanner is used to perform non-contact scanning on the gripping candidate region to generate a three-dimensional model of the surface, the point cloud data generated by scanning is analyzed to obtain the change range of the surface height, i.e., the maximum height and minimum height difference, thereby obtaining the undulation degree; or a laser profilometer is used to measure the vertical distance change of the surface along a certain direction to generate a surface profile, and the maximum height difference and average height change of the profile line are calculated by software to obtain the surface undulation degree. The method for obtaining the surface roughness of the gripping candidate region is as follows: the surface roughness reflects the delicacy of the microstructure of the surface of the object, and is usually determined by measuring the texture characteristics or small-scale height change of the surface, a roughness measuring instrument such as a portable surface roughness meter is used to measure the microtexture of the surface by a contact or non-contact method; or an optical interference technology is used to measure the micro-height change of the surface by light wave interference to generate a micro-height distribution map of the surface, and the roughness parameter is calculated.

[0021] Step 2: According to the surface structure feature data of each gripping candidate region, the distance between each gripping candidate region and the center of gravity of the object to be gripped is combined to evaluate the stability score of each gripping candidate region, and based on the stability score of each gripping candidate region, a gripping candidate region sequence is formed in descending order.

[0022] The logic of the stability score of each clamping candidate region is as follows: the surface flatness coefficient of each clamping candidate region is calculated based on the surface structure feature data of each clamping candidate region, the surface flatness coefficient is used to represent the clamping difficulty of the clamping candidate region, and the stability score of each clamping candidate region is calculated by combining the surface flatness coefficient and the distance between each clamping candidate region and the gravity center of the object to be clamped. The formula for calculating the surface flatness coefficient is: ; In the formula, is the surface flatness coefficient of the i-th clamping candidate region, is the maximum fluctuation difference normalization value of the i-th clamping candidate region, is the average roughness normalization value of the i-th clamping candidate region, and are the weight coefficients of the roughness and the maximum fluctuation difference of the clamping candidate region, respectively, wherein , and and are both greater than 0, and i is the index of the clamping candidate region. It should be noted that the surface flatness coefficient of the i-th clamping candidate region is used to represent the clamping difficulty of the clamping candidate region, and is mainly used to quantify the surface features of the region for comparison with other candidate regions. It considers two dimensions of surface roughness and surface fluctuation degree, which can help to judge whether the object is easy to slip, whether the clamping force is sufficient, and the stability of the contact, The larger the value is, the more stable the contact is, and the smaller the clamping difficulty is. wherein the surface roughness is an important indicator of the surface microstructure, the higher the roughness is, the greater the surface friction is, and the stronger the clamping stability is, so the average roughness normalization value of the i-th clamping candidate region is proportional to , and the square root of the average roughness normalization value of the i-th clamping candidate region is used to calculate the flatness coefficient to emphasize its influence on clamping stability; The surface relief difference is an important indicator of the macroscopic features of the surface, reflecting the shape change of the surface on a larger scale. The maximum relief difference usually represents the overall height difference between the protrusions and depressions of the surface of the candidate region, that is, the difference between the maximum height and the minimum height, which directly affects the contact quality between the mechanical gripper and the object surface. A larger surface height difference means that the clamping surface of the mechanical gripper may not fully conform to the object surface when in contact, thereby causing uneven stress or unstable clamping. In this case, the clamping difficulty increases and the stability decreases. A relatively flat surface means that the mechanical gripper can more evenly contact the object surface, thereby enhancing the clamping stability and reducing the risk of slipping or loosening. Therefore, the maximum relief difference normalized value of the i-th clamping candidate region is inversely proportional to The normalized value of the maximum relief difference is processed to reduce its influence. The logarithmic function means that for smaller relief differences, the increase in influence is smaller, while for larger relief differences, the influence gradually decreases, embodying a nonlinear relationship.

[0023] The maximum relief difference of the i-th clamping candidate region is specifically defined as the difference between the highest point and the lowest point on the surface of the i-th clamping candidate region. The logic for obtaining the maximum relief difference normalized value of the i-th clamping candidate region is as follows: calculate the difference between the highest point and the lowest point of all clamping candidate regions, determine the maximum difference value, and normalize the maximum relief difference of each clamping candidate region by the maximum difference value. Specifically, the ratio of the maximum relief difference of each clamping candidate region to the maximum difference value is taken as the maximum relief difference normalized value. The average roughness of the clamping candidate region is used to represent the relief degree of the region. The formula for calculating the average roughness normalized value of the i-th clamping candidate region is as follows: ; In the formula, is the average roughness of the i-th clamping candidate region, is the maximum roughness of all clamping candidate regions, where the average roughness of the i-th clamping candidate region is calculated as follows: randomly select a number of detection sub-regions on the surface of the i-th clamping candidate region, and calculate the average roughness of all detection sub-regions. The average roughness of the clamping candidate region is taken as the average roughness of the clamping candidate region. The formula for calculating the average roughness of all detection sub-regions is as follows: ; In the formula, is the roughness of the j-th detection sub-region on the surface of the i-th clamping candidate region, where j is the index of the detection sub-region, , ​The total number of detection sub-regions randomly selected on the surface of the candidate gripping region; where the roughness and undulation degree mentioned above specifically refer to the undulation degree and roughness of the contact gripping surface between the target encircling mechanical claw and each candidate gripping region.

[0024] The formula used to calculate the stability score of each candidate region is as follows: ; In the formula, The stability score for the i-th candidate region is given. This represents the distance from the center of gravity of the i-th candidate gripping region to the center of gravity of the object to be gripped. Specifically, it refers to the straight-line distance from the center of gravity of the i-th candidate gripping region to the center of gravity of the object to be gripped. This represents the maximum distance from the center of gravity of the object to be grabbed across all candidate grabbing regions. It should be noted that, Indicates the first A stability score is given for each candidate gripping region. This score aims to comprehensively evaluate the potential stability of each candidate gripping region during the gripping process, specifically characterizing it by combining the surface flatness coefficient and the distance to the center of gravity of the object to be gripped. A larger value indicates a more stable selection of candidate regions and a higher selection priority. A high surface flatness coefficient This means that the candidate region for gripping is of good quality, has high stability, and is relatively easy to grip. and Proportional; When the candidate gripping area is located far from the object's center of gravity, the gripping force applied at that location will generate a larger torque. Torque is the product of force and distance; the greater the distance, the larger the torque generated by the applied force. During gripping, a larger torque may cause the object to rotate or tilt, increasing the risk of slipping or falling. In this case, gripping stability is compromised. The object's center of gravity is the center of its mass distribution. If the gripping point is too far from the center of gravity, the object may be more prone to losing balance under gravity. Especially when the object is irregular or has a complex shape, the gripping point needs to be chosen close to the center of gravity to ensure that the object does not tilt or flip during gripping. A gripping area that is far away may cause the object's center of gravity to not coincide with the line of action of the gripping force, thus affecting overall stability. Therefore, the greater the distance, the lower the stability score. and Inversely proportional, by normalizing the distance to the maximum distance This allows for comparison of the impact of distance between different candidate regions.

[0025] The stability scores of the clamping candidate regions are sorted in descending order to form a clamping candidate region sequence.

[0026] Step 3: The maximum clamping force that can be borne by each clamping candidate region is determined based on the order of the clamping candidate region sequence, and the minimum clamping pressure required for stable clamping at each clamping candidate region is calculated based on the gravity of the object to be clamped, and the minimum clamping pressure is compared with the maximum clamping force that can be borne to determine the final clamping position.

[0027] The logic for determining the maximum clamping force that can be borne by each clamping candidate region based on the material characteristics of each clamping candidate region is as follows: a finite element model of each clamping candidate region is constructed, and through finite element analysis, the pressure that the object to be clamped is subjected to when the deformation of each clamping candidate region reaches the maximum irreversible deformation is determined, which is taken as the maximum clamping force that can be borne by the corresponding clamping candidate region. The specific steps include: determining the material properties of each part of the clamped object, such as elastic modulus, yield strength, Poisson's ratio, etc., using computer-aided design (CAD) software such as SolidWorks, AutoCAD, etc. to establish a three-dimensional geometric model of the object and the clamping device, including the shape, size and relative position of the clamping region, according to the material characteristic data, inputting the physical parameters such as elastic modulus, yield strength, Poisson's ratio into the finite element software to ensure that the model reflects the mechanical behavior of the actual material, setting the fixed boundary conditions of the model according to the actual situation, fixing the bottom of the object or the support part of the clamping device, applying uniform pressure in the stress area, running finite element analysis, calculating stress, strain and deformation parameters during the application of pressure.

[0028] The formula for calculating the minimum clamping pressure for stable clamping based on the gravity of the object to be clamped is: ; In the formula, G is the gravity of the object to be clamped, P is the minimum clamping pressure of the clamping candidate region, μ is the friction coefficient of the clamping candidate region, where the friction coefficient of the clamping candidate region specifically refers to the friction coefficient of the contact clamping surface between the target ring-type mechanical gripper and each clamping candidate region.

[0029] It should be noted that in the clamping process, in order to ensure that the object does not slip, the weight of the object must be overcome, and in order to keep the object stationary without slipping, the friction generated by clamping must be greater than or equal to the resistance of the object under the action of gravity, and the logical basis of the formula is the principle of balance of friction. When clamping the object, insufficient clamping pressure may cause the friction to be unable to resist the gravity, resulting in unstable clamping, object slipping or falling off. By calculating the minimum clamping pressure required, the safety and stability of the clamping process can be ensured.

[0030] The specific method for obtaining the friction coefficient of the clamped candidate area is that the value of the friction coefficient is usually listed in the technical manual, engineering standard, scientific literature of the material. The friction coefficient of many common materials such as metal, plastic, rubber and different surfaces such as smooth, rough, coating has been widely studied and recorded, or the friction coefficient is measured by friction test.

[0031] In order to judge whether each clamped candidate area meets the clamping condition, the minimum clamping pressure of each clamped candidate area is compared with the maximum clamping force that can be borne in sequence according to the sequence of the clamped candidate area sequence, and the first clamped candidate area that meets the clamping condition is the final clamping position. The clamping condition is that the product of the minimum clamping pressure of the clamped candidate area and the maximum adjustment range is less than the maximum clamping force that can be borne by the clamped candidate area, and the formula on which the clamping condition is based is: ; In the formula, is the maximum adjustment range, is the maximum clamping force that can be borne by the clamped candidate area, where yz is greater than 1, and can be set according to expert experience, generally between 1.2 and 1.8. The logic for setting is that during transportation, the clamping situation may be affected by external environment, and the clamping pressure needs to be increased to achieve stable transportation when the clamping situation is affected, so the maximum adjustment range is used as a control margin, so that the clamping pressure is increased during transportation without causing deformation of the object to be clamped.

[0032] In order to judge whether each clamped candidate area meets the clamping condition, the minimum clamping pressure of each clamped candidate area is calculated in sequence according to the sequence of the clamped candidate area sequence, and if the clamping condition is met, the current clamped candidate area is taken as the final clamping position, otherwise the current clamped candidate area is replaced. The current clamping area is replaced in sequence according to the sequence of the clamped candidate area sequence until the clamping condition is met.

[0033] Step 4: clamping the object to be clamped at a minimum clamping pressure at the clamping position, setting the tightening step length of the stepping motor, and dynamically adjusting the minimum clamping pressure according to the vibration and slip parameters of the object to be clamped during transportation to complete clamping control.

[0034] The logic for dynamically adjusting the minimum clamping pressure according to the vibration and slip parameters of the object to be clamped during transportation is as follows: the vibration parameter of the object to be clamped is specifically the vibration acceleration, the clamping pressure is increased by one tightening step length of the stepping motor, the maximum vibration acceleration and the maximum slip distance during transportation under the current clamping state are detected, it is judged whether the maximum vibration acceleration and the maximum slip distance fall within the corresponding preset safety intervals, if both fall within the corresponding safety intervals, transportation is carried out at the current clamping pressure, if both do not fall within the corresponding safety intervals, the clamping pressure is increased by one tightening step length of the stepping motor again at the current clamping pressure, and it is further judged whether the maximum vibration acceleration and the maximum slip distance both fall within the corresponding safety intervals, and the iteration operation is carried out in turn until the determined clamping pressure is met. The corresponding preset safety intervals include a vibration acceleration safety interval and a slip distance safety interval, and the minimum values of the intervals are both 0, and the maximum values are set by the maximum values of the vibration acceleration and the slip distance corresponding to no safety problems in actual transportation.

[0035] By monitoring the vibration acceleration and the slip distance of the object to be clamped in real time, the clamping pressure can be dynamically adjusted to ensure that the clamping force is always within a safe and effective range, thereby significantly enhancing the stability of clamping and reducing the risk of the object slipping or falling due to vibration or external impact during transportation; the logic of dynamically adjusting the clamping pressure ensures that the clamping force does not exceed the maximum bearing force of the clamping candidate area, avoiding structural damage or material fatigue caused by excessive clamping force. During clamping, the tightening step length of the stepping motor can finely control the change of the clamping force. By increasing the clamping pressure only when necessary, unnecessary energy consumption can be effectively reduced, and energy waste caused by excessive clamping can be avoided.

[0036] Please refer to Figure 5 The application also provides a step motor-based ring-type mechanical gripper clamping control system for executing the above-mentioned step motor-based ring-type mechanical gripper clamping control method, comprising: A clamping area planning module is used to obtain the clamping width of a target ring-type mechanical gripper, divide the object to be clamped into a plurality of clamping candidate areas along the length direction of the object to be clamped based on the clamping width of the target ring-type mechanical gripper, and collect surface structure feature data of each clamping candidate area. The clamping stress analysis module is configured to evaluate a stability score of each clamping candidate region according to surface structure feature data of each clamping candidate region and a distance between each clamping candidate region and a gravity center of the object to be clamped, and form a clamping candidate region sequence by descending order arrangement based on the stability score of each clamping candidate region. The clamping region replacement module is configured to determine a maximum clamping force that can be borne by each clamping candidate region in sequence based on an order of the clamping candidate region sequence, determine a clamping candidate region that meets a clamping condition based on the minimum clamping pressure and a comparison between the minimum clamping pressure and the maximum clamping force that can be borne. The clamping force dynamic adjustment module is configured to clamp the object to be clamped at the minimum clamping pressure by the clamping candidate region that meets the clamping condition, set a tightening step of the stepper motor, and dynamically adjust the minimum clamping pressure according to vibration and slip parameters of the object to be clamped in the transportation process to complete clamping control.

[0037] The above formulas are all dimensionless numerical calculations, and the formulas are obtained by software simulation of a large amount of data to obtain a formula closest to the actual situation. The preset parameters in the formula are set by a person skilled in the art according to the actual situation.

[0038] The above embodiments can be realized wholly or partially by software, hardware, firmware or any combination thereof. When realized by software, the above embodiments can be realized in the form of a computer program product wholly or partially. Those skilled in the art can realize that the units and algorithm steps of the examples described in connection with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized by hardware or software methods depends on the specific application and design constraints of the technical solutions.

[0039] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, which can be located in one place or distributed on multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0040] The above is merely specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed in the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for controlling a ring-shaped mechanical gripper based on a stepper motor, characterized in that, The specific steps include: The clamping width of the target encircling mechanical claw is obtained. Based on the clamping width of the target encircling mechanical claw, the object to be clamped is divided into several clamping candidate regions along the length direction of the object to be clamped, and the surface structure feature data of each clamping candidate region is collected. Based on the surface structure feature data of each gripping candidate region and the distance between each gripping candidate region and the center of gravity of the object to be gripped, the stability score of each gripping candidate region is evaluated. Based on the stability score of each gripping candidate region, the gripping candidate regions are arranged in descending order to form a sequence of gripping candidate regions. Based on the order of the candidate gripping regions, the maximum gripping force that each candidate gripping region can withstand is determined sequentially. Based on the weight of the object to be gripped, the minimum gripping pressure that ensures stable gripping at each candidate gripping region is calculated. The minimum gripping pressure is compared with the maximum gripping force that can be withstood to determine the final gripping position. The object to be clamped is clamped at the clamping position with the minimum clamping pressure. The tightening step length of the stepper motor is set, and the minimum clamping pressure is dynamically adjusted according to the vibration and slippage parameters of the object to be clamped during transportation to complete the clamping control.

2. The method for controlling a ring-shaped mechanical gripper based on a stepper motor according to claim 1, characterized in that: The clamping width of the target encircling mechanical claw specifically refers to the clamping surface width of the target encircling mechanical claw; Based on the gripping width of the target encircling robotic gripper, the object to be gripped is divided into several gripping candidate regions along the length direction of the object to be gripped. The specific logic is as follows: a sliding window is set with the gripping width of the target encircling robotic gripper, and the gripping width is the width of the sliding window. One end of the sliding window is set on the edge of the object to be gripped along the length direction of the object to be gripped. The sliding window is controlled to move along the length direction of the object to be gripped in increments of 2 units. Each time it moves, the area where the sliding window is located is recorded as a gripping candidate region. This continues until after a certain movement, the remaining length of the surface of the object to be gripped is less than the width of the sliding window, at which point the movement stops, and several gripping candidate regions are obtained during the entire movement process. Surface structure feature data of each clamping candidate region are collected. The surface structure feature data specifically includes: the degree of undulation of the surface of each clamping candidate region and the surface roughness of the clamping candidate region.

3. The method for controlling a ring-shaped mechanical gripper based on a stepper motor according to claim 2, characterized in that: The logic behind evaluating the stability score of each candidate gripping region is as follows: The surface flatness coefficient of each candidate gripping region is calculated based on its surface structure feature data. This coefficient is used to characterize the gripping difficulty of the candidate region. Finally, the stability score of each candidate gripping region is calculated by combining the surface flatness coefficient with the distance between the candidate region and the center of gravity of the object to be gripped. The specific formula for calculating the surface flatness coefficient is as follows: ； In the formula, Let be the surface smoothness coefficient of the i-th candidate region. Let be the normalized value of the maximum fluctuation difference of the i-th pinch candidate region. Let be the normalized average roughness value of the i-th candidate region. and These are the weighting coefficients for the roughness and maximum fluctuation difference of the candidate region, respectively. ,and and All are greater than 0, where i is the index of the candidate region to be selected; The maximum fluctuation difference of the i-th candidate region is specifically defined as the difference between the highest and lowest points on the surface of the i-th candidate region. The logic for obtaining the normalized value of the maximum fluctuation difference of the i-th candidate region is as follows: calculate the difference between the highest and lowest points of all candidate regions, determine the maximum difference, and normalize the maximum fluctuation difference of each candidate region by using the maximum difference. Specifically, the ratio of the maximum fluctuation difference of each candidate region to the maximum difference is used as the normalized value of the maximum fluctuation difference. The average roughness of the selected candidate regions is used to characterize the undulation of the region. The formula used to calculate the normalized value of the average roughness of the i-th selected candidate region is as follows: ； In the formula, Let be the average roughness of the i-th candidate region. The maximum roughness of all candidate regions to be gripped, where the average roughness of the i-th candidate region is... The specific method for obtaining the roughness is as follows: Several detection sub-regions are randomly selected from the surface of the i-th candidate gripping region, and the average roughness of all detection sub-regions is calculated. This average roughness is then used as the average roughness of the candidate gripping region. The formula used to calculate the average roughness of all detection sub-regions is as follows: ； In the formula, Let be the roughness of the j-th detection sub-region within the surface of the i-th candidate gripping region, where j is the index of the detection sub-region. , This represents the total number of randomly selected detection sub-regions on the surface of the candidate region.

4. The method for controlling a ring-shaped mechanical gripper based on a stepper motor according to claim 3, characterized in that: The formula used to calculate the stability score of each candidate region is as follows: ； In the formula, The stability score for the i-th candidate region is given. This represents the distance from the center of gravity of the i-th candidate gripping region to the center of gravity of the object to be gripped. Specifically, it refers to the straight-line distance from the center of gravity of the i-th candidate gripping region to the center of gravity of the object to be gripped. This represents the maximum distance from the center of gravity of the object to be grabbed across all candidate grabbing regions. Based on the stability score of each candidate region, the candidate regions are sorted and formed into a sequence of candidate regions in descending order.

5. The method for controlling a ring-shaped mechanical gripper based on a stepper motor according to claim 4, characterized in that: The logic behind determining the maximum clamping force that each clamping candidate region can withstand based on the material characteristics of each clamping candidate region is as follows: construct a finite element model of each clamping candidate region, and through finite element analysis, determine the pressure that the object to be clamped experiences when the deformation of each clamping candidate region reaches the maximum irreversible deformation, and take this pressure as the maximum clamping force that the corresponding clamping candidate region can withstand. The formula used to calculate the minimum clamping pressure for stable clamping, based on the weight of the object to be clamped, is as follows: ； In the formula, Let g be the weight of the object to be grasped. To determine the minimum clamping pressure for gripping the candidate region, The friction coefficient is used to select the candidate region.

6. The method for controlling a ring-shaped mechanical gripper based on a stepper motor according to claim 5, characterized in that: Following the sequence of candidate clamping regions, the minimum clamping pressure and the maximum clamping force that each candidate region can withstand are compared sequentially to determine whether each candidate region meets the clamping condition. The first candidate region that meets the clamping condition is designated as the final clamping position. Specifically, the clamping condition is that the product of the minimum clamping pressure and the maximum adjustment range of the candidate region is less than the maximum clamping force that the candidate region can withstand. The formula underlying this clamping condition is as follows: ； In the formula, For the maximum adjustment range, The maximum clamping force that the candidate region can withstand is yz, where yz is greater than 1.

7. The method for controlling a ring-shaped mechanical gripper based on a stepper motor according to claim 5, characterized in that: The logic for dynamically adjusting the minimum clamping pressure based on the vibration and sliding parameters of the object to be clamped during transportation is as follows: The vibration parameters of the object to be clamped specifically refer to the vibration acceleration. The clamping pressure is increased by one tightening step length through a stepper motor. The maximum vibration acceleration and maximum sliding distance during transportation under the current clamping state are detected. It is determined whether the maximum vibration acceleration and maximum sliding distance fall within the preset corresponding safety range. If they both fall within the corresponding safety range, transportation is carried out with the current clamping pressure. If they do not both fall within the corresponding safety range, the clamping pressure is increased again by one tightening step length through a stepper motor on the current clamping pressure. It is then further determined whether the maximum vibration acceleration and maximum sliding distance both fall within the corresponding safety range. This iterative operation is performed until the determined clamping pressure is met.

8. A ring-shaped mechanical gripper control system based on a stepper motor, characterized in that: The stepper motor-based encircling mechanical gripper control system is used to execute the stepper motor-based encircling mechanical gripper control method according to any one of claims 1-7, including: The gripping region planning module is used to obtain the gripping width of the target encircling mechanical claw. Based on the gripping width of the target encircling mechanical claw, the object to be gripped is divided into several gripping candidate regions along the length direction of the object to be gripped, and the surface structure feature data of each gripping candidate region is collected. The clamping force analysis module is used to evaluate the stability score of each clamping candidate region based on the surface structure feature data of each clamping candidate region and the distance between each clamping candidate region and the center of gravity of the object to be clamped. Based on the stability score of each clamping candidate region, the clamping candidate regions are arranged in descending order to form a clamping candidate region sequence. The clamping area replacement module is used to determine the maximum clamping force that each clamping candidate area can withstand based on the order of the clamping candidate area sequence, and to calculate the minimum clamping pressure to ensure stable clamping at each clamping candidate area based on the gravity of the object to be clamped, and to compare the minimum clamping pressure with the maximum clamping force that can be withstood to determine the final clamping position. The clamping force dynamic adjustment module is used to clamp the object to be clamped at the clamping position with the minimum clamping pressure. It sets the tightening step length of the stepper motor and dynamically adjusts the minimum clamping pressure according to the vibration and slippage parameters of the object to be clamped during transportation to complete the clamping control.

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