Mechanical part high-precision clamping device based on flexible force feedback

Abstract

The invention relates to the field of mechanical clamping regulation and control, in particular to a mechanical part high-precision clamping device based on flexible force feedback. The clamping device comprises a driving device and a plurality of mechanical claws, suction cups are mounted at the tail ends of the mechanical claws, the driving device is used for driving the mechanical claws and controlling the suction cups to clamp mechanical parts, and a plurality of pressure sensors are uniformly mounted at a plurality of positions of the bottoms of the suction cups so as to collect pressure data of the positions of the suction cups at each historical moment before the current moment; and a deployed feedback adjusting module is used for carrying out feedback adjustment on the output power of the driving device according to the pressure data of different positions of the bottom of the suction cup, and the clamping action of the mechanical part is controlled. According to the mechanical part clamping device, mechanical parts can be prevented from falling off during clamping, the mechanical parts can be prevented from being damaged due to too tight clamping, and the clamping precision is improved.

Description

Technical Field

[0001] The present invention relates to the field of mechanical clamping regulation, and particularly to a high-precision clamping device for mechanical parts based on flexible force feedback. Background Art

[0002] In the field of mechanical manufacturing, high-precision clamping devices are the core components for realizing precision machining and are widely used in various processing and production processes to ensure that parts remain stable during machining and assembly, avoid movement or vibration, thereby improving processing efficiency and product quality.

[0003] In related technologies, each mechanical claw of the clamping device usually completes the clamping action on mechanical parts with a fixed output power. However, in the actual machining process, due to the irregularity of the surface of mechanical parts and the easy occurrence of vibration during the clamping of mechanical parts by the clamping device, the clamping force of the existing clamping device on mechanical parts is uneven, which easily causes the dropping of mechanical parts and over-tight clamping of mechanical parts, damaging the parts, thereby reducing the clamping accuracy. Summary of the Invention

[0004] In order to solve the technical problem that the existing clamping device has uneven clamping force on mechanical parts, which easily causes the dropping of mechanical parts and over-tight clamping of mechanical parts, damaging the parts, thereby reducing the clamping accuracy, the purpose of the present invention is to provide a high-precision clamping device for mechanical parts based on flexible force feedback, and the specific technical solution adopted is as follows:

[0005] The present invention provides a high-precision clamping device for mechanical parts based on flexible force feedback. The clamping device includes a driving device and a plurality of mechanical claws. A suction cup is installed at the end of each mechanical claw. The driving device is used to drive the mechanical claws and control the suction cups to clamp mechanical parts. The clamping device further includes a feedback adjustment module. A plurality of pressure sensors are evenly installed at multiple positions at the bottom of the suction cup. The pressure sensors are used to obtain the pressure data at each historical moment within a preset time period before the current moment at their respective positions. The feedback adjustment module is used to perform feedback adjustment on the output power of the driving device according to the pressure data and control the clamping action of the mechanical parts, including:

[0006] Taking any one of the suction cups as the target suction cup, obtaining the part stability influence degree of each position at the bottom of the target suction cup according to the fluctuation difference of the pressure data between the positions where the pressure sensors are located at the bottom of the target suction cup; obtaining the real-time part dropping possibility of the clamping device according to the part stability influence degree of each position at the bottom of each suction cup;

[0007] According to the real-time part dropping possibility of the clamping device and the pressure data at different positions of the suction cup in real time, feedback regulates the output power of the driving device for the robotic gripper in real time, obtains the regulated output power of the driving device for the robotic gripper at the next moment, the clamping device clamps the mechanical part with the regulated output power, and predicts the part dropping possibility at future moments according to the part dropping possibility of the clamping device at different moments, and obtains the stop moment of the clamping action.

[0008] Further, the obtaining of the part stability influence degree of each position at the bottom of the target suction cup includes:

[0009] According to the fluctuations of the pressure data at each position where each pressure sensor is located at the bottom of the target suction cup at each historical moment, obtain the pressure fluctuation degree of each position at the bottom of the target suction cup;

[0010] Take the position where any one pressure sensor is located at the bottom of the target suction cup as the target position, take the position symmetrical to the target position as the symmetrical position of the target position, and take the other positions except the target position and the symmetrical position of the target position as the reference positions of the target position;

[0011] Perform a negative correlation mapping on the difference in the pressure fluctuation degree between the target position and the symmetrical position of the target position to obtain the pressure fluctuation similarity of the target position;

[0012] Accumulate the differences in the pressure fluctuation degree between the target position and each reference position to obtain the pressure fluctuation difference degree of the target position;

[0013] Take the product value of the pressure fluctuation similarity and the pressure fluctuation difference degree as the part stability influence degree of the target position.

[0014] Further, the obtaining of the pressure fluctuation degree of each position at the bottom of the target suction cup includes:

[0015] Extract the extreme values from the pressure data of all historical moments at each position where each pressure sensor is located at the bottom of the target suction cup, take two adjacent extreme values as an extreme value group, and take the absolute value of the difference between the two extreme values in each extreme value group as the pressure change amplitude of each extreme value group;

[0016] Take the average value of the pressure change amplitudes of all extreme value groups at each position at the bottom of the target suction cup as the pressure fluctuation degree of each position at the bottom of the target suction cup.

[0017] Further, the obtaining of the real-time part dropping possibility of the clamping device includes:

[0018] At the bottom of the target suction cup, an initial vibration vector at the position where each pressure sensor is located is constructed. Among them, the direction of the initial vibration vector at each position is the direction from the center of the target suction cup to each position, and the length of the initial vibration vector at each position is the part stability influence degree at each position at the bottom of the target suction cup;

[0019] The positions where two pressure sensors symmetric to each other on the bottom of the target suction cup are used as a symmetric position group of the target suction cup. The sum value of the part stability influence degrees at the two positions in each symmetric position group is used as the comprehensive influence degree of each symmetric position group. The two positions in the symmetric position group with the largest comprehensive influence degree are used as the key vibration positions at the bottom of the target suction cup;

[0020] Based on the initial vibration vectors at all positions in the preset neighborhood of each key vibration position at the bottom of the target suction cup, two suspected vibration vectors of the target suction cup are obtained;

[0021] Two symmetric suction cups are used as a symmetric suction cup group. Any symmetric suction cup group is used as the target symmetric suction cup group. A projection plane of the target symmetric suction cup group is constructed. The projection plane is perpendicular to the connection line of the midpoints of the two suction cups in the target symmetric suction cup group and passes through the center point of the connection line;

[0022] The two suspected vibration vectors of each suction cup in the target symmetric suction cup group are projected onto the projection plane to obtain two projection vectors of each suction cup in the target symmetric suction cup group;

[0023] In the two suction cups of the target symmetric suction cup group, one projection vector is respectively selected. The two selected projection vectors are used as a projection vector group. The included angle between the two projection vectors in each projection vector group is used as the reference angle of each projection vector group. The two projection vector groups with the smallest reference angle are used as the reference projection vector groups of the target symmetric suction cup group;

[0024] Based on the reference angle of each reference projection vector group of the target symmetric suction cup group and the projection vectors in each reference projection vector group, the part dropping coefficient of the target symmetric suction cup group is obtained;

[0025] The average value of the part dropping coefficients of all symmetric suction cup groups is used as the real-time part dropping possibility of the clamping device.

[0026] Further, the obtaining of the two suspected vibration vectors of the target suction cup includes:

[0027] The sum value of the initial vibration vectors at all positions in the preset neighborhood of each key vibration position is used as the suspected vibration vector of the target suction cup.

[0028] Further, the obtaining of the part dropping coefficient of the target symmetric suction cup group includes:

[0029] Performing a negative correlation mapping on the average value of the reference angles of the two reference projection vector groups of the target symmetric suction cup group to obtain the first part dropping evaluation value of the target symmetric suction cup group;

[0030] Taking the sum value of the two projection vectors in each reference projection vector group as the composite projection vector of each reference projection vector group, and taking the sum value of the moduli of the composite projection vectors of the two reference projection vector groups as the second part dropping evaluation value of the target symmetric suction cup group;

[0031] After comprehensively processing the first part dropping evaluation value and the second part dropping evaluation value and performing normalization processing, the part dropping coefficient of the target symmetric suction cup group is obtained.

[0032] Further, the obtaining of the adjustment output power of the driving device for the mechanical claw at the next moment includes:

[0033] Taking the average value of the pressure data at the positions of all the pressure sensors on the suction cup at the end of each mechanical claw as the comprehensive pressure value of each mechanical claw in real time; according to the comprehensive pressure value of each mechanical claw in real time and the part dropping possibility of the clamping device in real time, obtaining the traction control weight of each mechanical claw in real time;

[0034] Based on the calculation formula of the adjustment output power, obtaining the adjustment output power of the driving device for each mechanical claw at the next moment, and the calculation formula of the adjustment output power is:

[0035] P k ′ =w k ×P max ×Δt + P k

[0036] where P k ′ represents the adjustment output power of the driving device for the k-th mechanical claw at the next moment; w k represents the traction control weight of the k-th mechanical claw in real time; P max represents the maximum output power of the driving device; Δt represents the sampling time interval of the pressure data; P k represents the output power of the driving device for the k-th mechanical claw in real time.

[0037] Further, the obtaining of the traction control weight of each mechanical claw in real time includes:

[0038] Based on the calculation formula of the traction control weight, obtaining the traction control weight of each mechanical claw in real time, and the calculation formula of the traction control weight is:

[0039] w k = (1 - norm(F k )) × U

[0040] where w k represents the real-time traction control weight of the k-th robotic gripper; F k represents the real-time comprehensive pressure value of the k-th robotic gripper; U represents the real-time part dropping possibility of the clamping device; norm() represents the normalization function.

[0041] Further, the obtaining of the stop moment of the clamping action includes:

[0042] Inputting the part dropping possibilities of the clamping device at different moments into a time series prediction algorithm, and outputting the predicted part dropping possibilities at multiple future moments;

[0043] Obtaining the stop moment of the clamping action according to the changes in the predicted part dropping possibilities at each future moment.

[0044] Further, the obtaining of the stop moment of the clamping action according to the changes in the predicted part dropping possibilities at each future moment includes:

[0045] Performing curve fitting on the predicted part dropping possibilities at all future moments to obtain a predicted fitting curve;

[0046] On the predicted fitting curve, taking the slope and the sum value of the predicted part dropping possibilities at each future moment as the judgment parameter for each future moment;

[0047] Taking the future moment with the minimum judgment parameter as the stop moment of the clamping action.

[0048] The present invention has the following beneficial effects:

[0049] In view of the uneven clamping force of the existing clamping device on mechanical parts, which is likely to cause the dropping of mechanical parts and over-tight clamping of mechanical parts, damaging the parts and thus reducing the clamping accuracy, this invention evenly installs multiple pressure sensors at different positions on the bottom of the suction cup that is in direct contact with the mechanical parts to collect the pressure data generated between different positions of the suction cup and the mechanical parts. Considering that when the suction cup clamps a mechanical part, if the pressure changes at different positions on the bottom of the suction cup are different, there may be an opening between the suction cup and the part, resulting in the invalidation of the vacuum environment and ultimately the dropping of the mechanical part. Therefore, in the embodiments of this invention, first, the fluctuation differences in the pressure data between the positions where each pressure sensor is located at the bottom of the target suction cup are analyzed. The influence degree of each position at the bottom of the target suction cup on maintaining the stability of the part during clamping is reflected by the part stability influence degree. Furthermore, the possibility of the part dropping during the clamping of the clamping device is reflected by the obtained part dropping possibility. And further based on the part dropping possibility, the driving device is feedback-regulated to adjust the real-time output power of the mechanical claw, so that when the clamping device clamps the mechanical part with the adjusted output power, it can clamp the mechanical part more stably, reduce the influence of vibration on the clamping device, prevent the dropping of the mechanical part, and then stop the power output and clamping action of the clamping device on the mechanical part at the obtained stop moment, prevent over-clamping of the mechanical part, and improve the clamping accuracy of the mechanical part. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] 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-described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0051] Figure 1 The overall structure diagram of a high-precision clamping device for mechanical parts based on flexible force feedback provided by an embodiment of the present invention;

[0052] Figure 2 The front view of a high-precision clamping device for mechanical parts based on flexible force feedback provided by an embodiment of the present invention;

[0053] Figure 3 The front view of the suction cup of a high-precision clamping device for mechanical parts based on flexible force feedback provided by an embodiment of the present invention;

[0054] Figure 4 The bottom view of the suction cup of a high-precision clamping device for mechanical parts based on flexible force feedback provided by an embodiment of the present invention;

[0055] Figure 5Schematic diagram of the position distribution of each pressure sensor at the bottom of the suction cup provided by an embodiment of the present invention;

[0056] Figure 6 Flowchart of a method for controlling the clamping action of mechanical parts provided by an embodiment of the present invention.

[0057] Reference numerals: 1 - motor, 2 - drive connection part, 3 - bracket, 4 - first connecting rod, 5 - second connecting rod, 6 - third connecting rod, 7 - rubber ring, 8 - connecting hole, 9 - rotating base, 10 - electro - controlled hydraulic rod, 11 - electro - controlled cylinder, 12 - suction cup, 13 - pressure sensor, 14 - cavity. Detailed implementation manners

[0058] In order to further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following, in combination with the accompanying drawings and preferred embodiments, details the specific implementation manners, structures, features, and effects of a high - precision clamping device for mechanical parts based on flexible force feedback proposed according to the present invention. In the following description, different "an 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.

[0059] 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.

[0060] The following specifically describes the specific solution of a high - precision clamping device for mechanical parts based on flexible force feedback provided by the present invention with reference to the accompanying drawings.

[0061] Please refer to Figures 1 to 4, which respectively show the overall structure diagram and front view of a high-precision clamping device for mechanical parts based on flexible force feedback provided by an embodiment of the present invention, as well as the front view and bottom view of the suction cup of the clamping device. Among them, the clamping device includes a driving device and a plurality of mechanical claws. The driving device is composed of a motor 1, a driving connection part 2 and a rotating base 9, and is fixed on a bracket 3. Each mechanical claw is composed of a first connecting rod 4, a second connecting rod 5, a third connecting rod 6, an electro-hydraulic rod 10 and a suction cup 12. Among them, both ends of the second connecting rod 5 are respectively hinged to one end of the first connecting rod 4 and one end of the third connecting rod 6. The other end of the first connecting rod 4 is hinged to the bracket 3. The other end of the third connecting rod 6 is fixedly connected to the suction cup 12. One end of the electro-hydraulic rod 10 is fixedly connected to the rotating base 9, and the other end is fixedly connected to the third connecting rod 6. An electro-control cylinder 11 is installed at the top of the suction cup 12. During the operation of the clamping device, the rotating base 9 controls the swing and telescopic movement of the electro-hydraulic rod 10 to achieve the clamping action of the mechanical parts. At the same time, when the suction cup contacts the mechanical parts, the electro-control cylinder 11 is used to extract or release the air in the cavity 14 of the suction cup 12, so that the suction cup 12 can adsorb or release the parts.

[0062] In order to improve the clamping accuracy of the clamping device for mechanical parts, an embodiment of the present invention also installs a rubber ring 7 at the bottom of each suction cup 12, and evenly installs a plurality of pressure sensors 13 at different positions at the bottom of the suction cup 12. The distance of each pressure sensor 13 from the bottom edge of the suction cup 12 is the same. Among them, the internal closed space of the rubber ring 7 is filled with flexible particles and air. When the rubber ring 7 contacts the mechanical parts, the pressure generated between the two will compress the rubber ring 7, so that the rubber ring 7 triggers the pressure sensor 13, enabling the pressure sensor 13 to collect the pressure data of each historical moment at its location within a preset time period before the current moment. Among them, the preset time period is usually 10 to 20 seconds. In an embodiment of the present invention, the preset time period is set to 15 seconds, and the time interval for pressure data collection is set to 0.1 second. The preset time period and the data collection time interval can also be set by the implementer according to the specific implementation scenario, and are not limited herein. Please refer to Figure 5, which respectively shows the schematic diagram of the position distribution of each pressure sensor at the bottom of the suction cup provided by an embodiment of the present invention. Among them, a to h respectively represent the positions where the eight pressure sensors are located. In an embodiment of the present invention, 8 pressure sensors are installed at the bottom of each suction cup 12. It should be noted that the number of pressure sensors 13 installed on each suction cup 12 and the number of suction cups 12 both need to be even numbers, so that there is a symmetric pressure sensor 13 or suction cup 12 for each pressure sensor 13 or suction cup 12, which is convenient for subsequent calculation and analysis. At the same time, a feedback adjustment module is further included in the clamping device of the embodiment of the present invention. The feedback adjustment module is used to perform feedback adjustment on the output power of the driving device according to the pressure data and control the clamping action of the mechanical parts, so as to achieve precise clamping of the mechanical parts.

[0063] Please refer to Figure 6 , which shows the flowchart of the method for controlling the clamping action of mechanical parts provided by an embodiment of the present invention. The method includes:

[0064] Step S1: Take any one suction cup as the target suction cup, and obtain the part stability influence degree of each position at the bottom of the target suction cup according to the fluctuation difference of the pressure data between the positions where each pressure sensor is located at the bottom of the target suction cup; obtain the real-time part dropping possibility of the clamping device according to the part stability influence degree of each position at the bottom of each suction cup.

[0065] Since the maximum suction force of the suction cup cavity on the mechanical part in the vacuum state is constant, and the part is subjected to the pressure of the suction cup, jointly making the mechanical part in a static state relative to the clamping device. When the suction cup clamps the mechanical part, if the pressure changes at each position at the bottom of the suction cup are different, it is possible that there is an opening between the suction cup and the part, resulting in the invalidation of the vacuum environment and ultimately the dropping of the mechanical part. Therefore, when the clamping device clamps the mechanical part and vibrates during movement or processing, if the pressure change situation between a certain position and other positions at the bottom of the suction cup is quite different, it means that the clamping effect at this position at the bottom of the suction cup is poor, and this position is likely to cause the part to drop. Therefore, in the embodiment of the present invention, first, any one suction cup is taken as the target suction cup, and the fluctuation difference of the pressure data between the positions where each pressure sensor is located at the bottom of the target suction cup is analyzed. The part stability influence degree reflects the influence degree of each position at the bottom of the target suction cup on maintaining the stability of the part when clamping the part. The greater the part stability influence degree, the greater the influence of this position on the clamping stability of the part, and the more likely it is to cause the instability of the part and the more likely this position is to cause the part to drop. Subsequently, based on the part stability influence degrees of different positions at the bottom of each suction cup, the real-time part dropping possibility of the clamping device can be accurately calculated and analyzed. It should be noted that the positions at the bottom of the suction cup mentioned in the embodiment of the present invention all refer to the positions where the pressure sensors are located at the bottom of the suction cup.

[0066] Preferably, in an embodiment of the present invention, the method for obtaining the part stability influence degree at each position of the bottom of the target suction cup specifically includes:

[0067] According to the fluctuations of the pressure data at each position where each pressure sensor is located at the bottom of the target suction cup at each historical moment, obtain the pressure fluctuation degree at each position of the bottom of the target suction cup. The greater the pressure fluctuation degree, the more obvious the fluctuation or change of the pressure data at each position of the bottom of the target suction cup.

[0068] Preferably, in an embodiment of the present invention, the method for obtaining the pressure fluctuation degree at each position of the bottom of the target suction cup specifically includes:

[0069] Extract the extreme values from the pressure data at all historical moments at each position where each pressure sensor is located at the bottom of the target suction cup. Among them, the extreme values include maximum values and minimum values. Take two adjacent extreme values as an extreme value group. Usually, each extreme value group contains a minimum value and a maximum value, and take the absolute value of the difference between the two extreme values in each extreme value group as the pressure change amplitude of each extreme value group. The greater the pressure change amplitude, the greater the data difference between the two extreme values in the extreme value group, indicating that the fluctuation of the pressure data at each position is more obvious. Furthermore, the average value of the pressure change amplitudes of all extreme value groups at each position of the bottom of the target suction cup can be used as the pressure fluctuation degree at each position of the bottom of the target suction cup.

[0070] In an embodiment of the present invention, the extreme values can be selected by means of curve fitting or local comparison, which is not limited herein. The process of selecting extreme values by curve fitting is as follows: First, use curve fitting methods such as the least squares method to perform curve fitting on the pressure data at all historical moments at each position where each pressure sensor is located at the bottom of the target suction cup, and take the temperature data corresponding to the points with a slope of 0 on the fitted curve as the extreme values; the process of selecting extreme values by local comparison is as follows: Compare the pressure data at each historical moment with the pressure data at other historical moments in the preset window. If the temperature data at this historical moment is greater than or less than the temperature data at other historical moments in the preset window, then take the temperature data at this moment as the extreme value. Among them, the length of the preset window can be set to 7, that is, the preset window contains the 6 other historical moments closest to this historical moment and this historical moment itself. The length of the preset window can also be set by the implementer according to the specific implementation scenario, which is not limited herein.

[0071] In other embodiments of the present invention, the pressure fluctuation degree at each position of the bottom of the target suction cup can also be obtained by calculating statistical quantities such as the variance or standard deviation of the pressure data at each position where each pressure sensor is located at the bottom of the target suction cup at all historical moments, which is not limited herein.

[0072] Then, take the position where any one of the pressure sensors is located at the bottom of the target suction cup as the target position, take the position symmetrical to the target position as the symmetrical position of the target position, and take the other positions except the target position and the symmetrical position of the target position as the reference positions of the target position. Please refer to Figure 5 , for example, if position a is the target position, then position e is the symmetrical position of position a, and the other positions are reference positions.

[0073] The more similar the pressure fluctuations at the target position and the symmetrical position are, the greater the impact of the target position on the stability of the part. Therefore, a negative correlation mapping can be performed on the difference in the degree of pressure fluctuation between the target position and the symmetrical position of the target position to obtain the pressure fluctuation similarity of the target position.

[0074] The greater the difference in the pressure fluctuations between the target position and the reference positions, the greater the impact of the target position on the stability of the part. The differences in the degree of pressure fluctuation between the target position and each reference position are accumulated to obtain the pressure fluctuation difference degree of the target position.

[0075] In the embodiments of the present invention, in the above analysis of the difference in the degree of pressure fluctuation, the analysis of the difference in the degree of pressure fluctuation between the target position and the symmetrical position, and the analysis of the difference in the degree of pressure fluctuation between the target position and each reference position can be realized by calculating the absolute value or the square value of the difference in the degree of pressure fluctuation, etc. This is not limited here.

[0076] Furthermore, the product value of the pressure fluctuation similarity and the pressure fluctuation difference degree is used as the part stability influence degree of the target position.

[0077] As an example, in an embodiment of the present invention, the expression of the part stability influence degree of the target position can be specifically, for example:

[0078]

[0079] Among them, A represents the part stability influence degree of the target position; V represents the degree of pressure fluctuation of the target position; V ′ represents the degree of pressure fluctuation of the symmetrical position of the target position; V i represents the degree of pressure fluctuation of the i-th reference position of the target position; I represents the number of reference positions of the target position; represents the pressure fluctuation similarity of the target position; represents the pressure fluctuation difference degree of the target position; ε 1 represents a preset first adjustment parameter for preventing the denominator from being 0, and the value range of ε 1 is [0.001, 0.01]. In an embodiment of the present invention, ε 1 is set to 0.01, and ε 1The specific value can also be set by the implementer according to the specific implementation scenario and is not limited here.

[0080] It should be noted that in other embodiments of the present invention, negative correlation mapping can also be achieved through other basic mathematical operations, which will not be elaborated here.

[0081] Through the same method as above, the part stability influence degree at the position of each pressure sensor at the bottom of the target suction cup can be obtained, as well as the part stability influence degree at the position of each pressure sensor at the bottom of each suction cup. Then, according to the part stability influence degree at each position at the bottom of each suction cup, the real-time part dropping possibility of the clamping device can be obtained, and the part dropping possibility during the clamping of the part by the clamping device is reflected by the part dropping possibility.

[0082] Preferably, in an embodiment of the present invention, the method for obtaining the real-time part dropping possibility of the clamping device specifically includes:

[0083] Since vibration has a certain direction, initially, at the bottom of the target suction cup, an initial vibration vector at the position of each pressure sensor is constructed, where the direction of the initial vibration vector at each position is the direction from the center of the target suction cup to each position, and the length of the initial vibration vector at each position is the part stability influence degree at each position at the bottom of the target suction cup.

[0084] The positions of two pressure sensors that are symmetric to each other at the bottom of the target suction cup are used as a symmetric position group of the target suction cup. Please refer to Figure 5 , where position a and e are a symmetric position group, position b and f are a symmetric position group, position c and g are a symmetric position group, position d and h are a symmetric position group. Then, the sum value of the part stability influence degrees of the two positions in each symmetric position group is used as the comprehensive influence degree of each symmetric position group, and the two positions in the symmetric position group with the largest comprehensive influence degree are used as the key vibration positions at the bottom of the target suction cup.

[0085] Then, according to the initial vibration vectors at all positions in the preset neighborhood of each key vibration position at the bottom of the target suction cup, two suspected vibration vectors of the target suction cup are obtained. Since the part usually vibrates in two directions, the directions of the two suspected vibration vectors represent the directions of part vibration, and the magnitudes of the two suspected vibration vectors represent the amplitudes of part vibration in these two directions.

[0086] Preferably, in an embodiment of the present invention, the method for obtaining the two suspected vibration vectors of the target suction cup specifically includes:

[0087] The sum value of the initial vibration vectors of all positions in the preset neighborhood of each key vibration position is used as the suspected vibration vector of the target suction cup. When the above analysis is performed for each key vibration position, a suspected vibration vector can be obtained. Therefore, two suspected vibration vectors can be obtained. Among them, all positions in the preset neighborhood include the key vibration position, and the length of the preset neighborhood is set to 5. That is to say, the preset neighborhood of a certain key vibration position includes the positions of the 4 other pressure sensors closest to this key vibration position and the key vibration position itself. Please refer to Figure 5 , if positions a and e are two key vibration positions, then the preset neighborhood of position a includes positions a, b, c, g, and h, and the preset neighborhood of position e includes positions c, d, e, f, and g. The specific length of the preset neighborhood can also be set by the implementer according to the specific implementation scenario and is not limited here.

[0088] By the same method as above, two suspected vibration vectors of each suction cup can be obtained. Then, two mutually symmetric suction cups are used as a symmetric suction cup group, and any one symmetric suction cup group is used as the target symmetric suction cup group. A projection plane of the target symmetric suction cup group is constructed. Among them, the projection plane is perpendicular to the line connecting the midpoints of the two suction cups in the target symmetric suction cup group and passes through the center point of this connection line. The two suspected vibration vectors of each suction cup in the target symmetric suction cup group are projected onto the projection plane to obtain two projection vectors of each suction cup in the target symmetric suction cup group.

[0089] In the two suction cups of the target symmetric suction cup group, one projection vector is respectively selected. The two selected projection vectors are used as a projection vector group. Then, the projection vector group includes one projection vector of one suction cup and one projection vector of the other suction cup in the target symmetric suction cup group. At this time, there are a total of four projection vector groups. Furthermore, the included angle between the two projection vectors in each projection vector group is used as the reference angle of each projection vector group, and the two projection vector groups with the smallest reference angles are used as the reference projection vector groups of the target symmetric suction cup group.

[0090] According to the reference angle of each reference projection vector group of the target symmetric suction cup group and the projection vectors in each reference projection vector group, the part dropping coefficient of the target symmetric suction cup group is obtained. The larger the part dropping coefficient, the greater the possibility of part dropping reflected when analyzing the target symmetric suction cup group.

[0091] Preferably, in an embodiment of the present invention, the method for obtaining the part dropping coefficient of the target symmetric suction cup group specifically includes:

[0092] The smaller the reference angles of the two reference projection vector groups of the target symmetric suction cup group are, the more consistent the vibration directions are, and the greater the possibility of the part falling off. Therefore, a negative correlation mapping is performed on the average value of the reference angles of the two reference projection vector groups of the target symmetric suction cup group to obtain the first part falling-off evaluation value of the target symmetric suction cup group.

[0093] Take the sum value of the two projection vectors in each reference projection vector group as the composite projection vector of each reference projection vector group. The larger the modulus length of the composite projection vectors of the two reference projection vector groups is, the greater the vibration amplitude is, and the greater the possibility of the part falling off. Therefore, the sum value of the modulus lengths of the composite projection vectors of the two reference projection vector groups can be used as the second part falling-off evaluation value of the target symmetric suction cup group.

[0094] Furthermore, the first part falling-off evaluation value and the second part falling-off evaluation value are combined and then normalized, and the calculation result is limited within the range of [0, 1], so as to obtain the part falling-off coefficient of the target symmetric suction cup group.

[0095] In the embodiments of the present invention, the combination of the two can be achieved by calculating the sum value or product value of the first part falling-off evaluation value and the second part falling-off evaluation value, and no limitation is made here.

[0096] In an embodiment of the present invention, the normalization process can be specifically, for example, the maximum-minimum normalization process or the use of activation functions or hyperbolic tangent functions, etc. to achieve the normalization process. And the normalization in subsequent steps can all adopt the maximum-minimum normalization process. In other embodiments of the present invention, other normalization methods can be selected according to the specific range of values, and this will not be elaborated here.

[0097] As an example, in an embodiment of the present invention, the expression of the part falling-off coefficient of the target symmetric suction cup group can be specifically, for example:

[0098]

[0099] where G represents the part falling-off coefficient of the target symmetric suction cup group; θ represents the average value of the reference angles of the two reference projection vector groups of the target symmetric suction cup group; represents the first part falling-off evaluation value of the target symmetric suction cup group; L 1 and L 2 respectively represent the modulus lengths of the composite projection vectors of the two reference projection vector groups; L 1 +L 2 represents the second part falling-off evaluation value of the target symmetric suction cup group; ε 2 represents a preset second adjustment parameter used to prevent the denominator from being 0, and the value range of ε 2 is [0.001, 0.01]. In an embodiment of the present invention, ε2 is set to 0.01, ε 2 The specific value of can also be set by the implementer according to the specific implementation scenario and is not limited herein.

[0100] It should be noted that in other embodiments of the present invention, negative correlation mapping can also be achieved through other basic mathematical operations, which will not be elaborated herein.

[0101] By the same method as above, the part dropping coefficient of each symmetric suction cup group can be obtained, and then the average value of the part dropping coefficients of all symmetric suction cup groups can be used as the real-time part dropping possibility of the clamping device.

[0102] Thus, the real-time part dropping possibility of the clamping device is obtained.

[0103] Step S2: According to the real-time part dropping possibility of the clamping device and the real-time pressure data at different positions of the suction cups, feedback and adjust the real-time output power of the driving device to the mechanical claw, obtain the adjusted output power of the driving device to the mechanical claw at the next moment, the clamping device clamps the mechanical part with the adjusted output power, and predict the part dropping possibility at future moments according to the part dropping possibility of the clamping device at different moments, and obtain the stop moment of the clamping action.

[0104] For the clamping device of the embodiment of the present invention, in addition to generating a certain adsorption force on the part through the suction cup, the traction force of the mechanical claw can also be adjusted to generate a pressure between the suction cup and the part, so as to adapt to parts with greater weight and reduce the generation of vibration. Since when different mechanical claws clamp parts with different shapes and increase the traction force with the same power, the increase amplitude of the pressure between different suction cups and parts is different, and the function of the rubber ring itself is to protect the surface of the part through flexible clamping and weaken the vibration to a certain extent. When the pressure is too large, the entire clamping device changes from flexible to rigid, resulting in an increase in the vibration amplitude and thus losing the vibration reduction function. Moreover, irregular parts will cause different clamping postures of each mechanical claw, and at this time, the pressure between different suction cups and parts is also different. Therefore, during the adjustment process, different mechanical claws should be controlled to adopt different output powers, so as to control different mechanical claws to complete the clamping action with different traction forces to ensure the force balance of the mechanical part.

[0105] At the same time, the greater the real-time part dropping possibility of the clamping device, it indicates that the mechanical part clamped by it at the current moment is more likely to drop. Therefore, in order to prevent the mechanical part from dropping, the embodiment of the present invention feedback and adjusts the real-time output power of the driving device to the mechanical claw according to the real-time part dropping possibility of the clamping device, obtains the adjusted output power of the driving device to the mechanical claw at the next moment, so that the subsequent clamping device can avoid the dropping of the mechanical part when clamping the mechanical part with the adjusted output power and improve the clamping effect.

[0106] Preferably, in an embodiment of the present invention, the method for obtaining the adjusted output power of the driving device for the mechanical claw at the next moment specifically includes:

[0107] Taking the average value of the pressure data at the positions of all the pressure sensors on the suction cups at the ends of each mechanical claw as the real-time comprehensive pressure value of each mechanical claw; obtaining the real-time traction control weight of each mechanical claw according to the real-time comprehensive pressure value of each mechanical claw and the real-time part dropping possibility of the clamping device.

[0108] Preferably, in an embodiment of the present invention, the method for obtaining the real-time traction control weight of each mechanical claw specifically includes:

[0109] Based on the calculation formula of the traction control weight, obtaining the real-time traction control weight of each mechanical claw, and the calculation formula of the traction control weight is:

[0110] w k =(1-norm(F k ))×U

[0111] wherein, w k represents the real-time traction control weight of the k-th mechanical claw; F k represents the real-time comprehensive pressure value of the k-th mechanical claw; U represents the real-time part dropping possibility of the clamping device; norm() represents the normalization function.

[0112] Among them, the larger the real-time comprehensive pressure value of a certain mechanical claw is, it indicates that the pressure between the current mechanical claw and the part is greater. At this time, it is necessary to reduce the traction provided to this mechanical claw, so as to avoid the entire clamping device changing from flexible to rigid when the pressure is too large, resulting in the loss of the vibration damping function. And when the real-time part dropping possibility of the clamping device is greater, at this time, it is necessary to increase the traction provided to this mechanical claw to avoid the part from dropping.

[0113] Then, based on the calculation formula of the adjusted output power, obtaining the adjusted output power of the driving device for each mechanical claw at the next moment, and the calculation formula of the adjusted output power is:

[0114] P k ′ =w k ×P max ×Δt+P k

[0115] wherein, P k ′ represents the adjusted output power of the driving device for the k-th mechanical claw at the next moment; w k represents the real-time traction control weight of the k-th mechanical claw; P maxrepresents the maximum output power of the driving device, and for the driving device, its maximum output power is a known value; Δt represents the sampling time interval of the pressure data; P k represents the real-time output power of the driving device for the k-th mechanical claw, and the real-time output power of the driving device for the mechanical claw is also a known value.

[0116] Furthermore, the obtained adjusted output power can be fed back to the driving device, and the driving device controls the mechanical claw to clamp the part with the corresponding adjusted output power. During the clamping process, the part dropping possibility of the clamping device at different moments can be obtained by the same method as above. In order to prevent the clamping device from over-clamping the part, it is also necessary to predict the part dropping possibility at future moments based on the part dropping possibility of the clamping device at different moments, so as to obtain the stop moment of the clamping action.

[0117] Preferably, in an embodiment of the present invention, the method for obtaining the stop moment of the clamping action specifically includes:

[0118] Input the part dropping possibility of the clamping device at different moments into the time series prediction algorithm, and output the part dropping prediction possibilities at multiple future moments. Then, based on the changes in the part dropping prediction possibilities at each future moment, obtain the stop moment of the clamping action. Among them, the time series prediction algorithm can be selected from the moving average method, the exponential smoothing method, the autoregressive moving average model, etc., which is not limited here.

[0119] Preferably, in an embodiment of the present invention, the method for obtaining the stop moment of the clamping action further includes:

[0120] Perform curve fitting on the part dropping prediction possibilities at all future moments to obtain a prediction fitting curve. The curve fitting method can be selected from the least squares method or other methods, which is not limited here.

[0121] When the change trend of the part dropping prediction possibility at a certain future moment is smaller and the part dropping prediction possibility is smaller, it indicates that this future moment is the best stop moment of the clamping action. Therefore, on the prediction fitting curve, take the sum value of the slope and the part dropping prediction possibility at each future moment as the judgment parameter for each future moment, and take the future moment with the smallest judgment parameter as the stop moment of the clamping action.

[0122] Subsequently, when the clamping device tightens the mechanical part during the clamping process, when the stop moment is reached, stop the further clamping action on the part to prevent over-clamping from damaging the part and losing the vibration damping function.

[0123] It should be noted that: the above order of the embodiments of the present invention is only for description and does not represent the superiority or inferiority of the embodiments. The processes depicted in the drawings do not necessarily require the particular order or sequential order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0124] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other. The key point of each embodiment is to illustrate the differences from other embodiments.

Claims

1. A high-precision clamping device for mechanical parts based on flexible force feedback, the clamping device comprising a driving device and a plurality of mechanical claws, a suction cup is installed at the end of the mechanical claw, the driving device is used to drive the mechanical claw and control the suction cup to clamp the mechanical parts, characterized in that: The clamping device further includes a feedback adjustment module. A plurality of pressure sensors are evenly installed at a plurality of positions on the bottom of the suction cup. The pressure sensors are used to obtain pressure data of the positions at each historical moment within a preset time period before the current moment. The feedback adjustment module is used to perform feedback adjustment on the output power of the driving device according to the pressure data and control the clamping action of the mechanical parts, including: Take any suction cup as the target suction cup, and obtain the part stability influence degree of each position at the bottom of the target suction cup according to the fluctuation difference of the pressure data between the positions of the pressure sensors at the bottom of the target suction cup; obtain the real-time part drop possibility of the clamping device according to the part stability influence degree of each position at the bottom of each suction cup; According to the real-time possibility of parts falling of the clamping device and the real-time pressure data of different positions of the suction cup, the real-time output power of the driving device to the mechanical claw is feedback-adjusted to obtain the adjusted output power of the driving device to the mechanical claw at the next moment. The clamping device clamps the mechanical parts with the adjusted output power, and according to the possibility of parts falling of the clamping device at different moments, the possibility of parts falling at future moments is predicted to obtain the stopping time of the clamping action.

2. A high-precision clamping device for mechanical parts based on flexible force feedback according to claim 1, characterized in that: The step of obtaining the stability influence of the part at each position on the bottom of the target suction cup includes: According to the fluctuation of the pressure data at each position of the pressure sensor at the bottom of the target suction cup at each historical moment, the pressure fluctuation degree at each position of the bottom of the target suction cup is obtained; The position of any pressure sensor at the bottom of the target suction cup is taken as the target position, the position symmetrical to the target position is taken as the symmetrical position of the target position, and other positions except the target position and the symmetrical position of the target position are taken as the reference positions of the target position; Performing negative correlation mapping on the difference in the pressure fluctuation degree between the target position and the symmetrical position of the target position to obtain the pressure fluctuation similarity of the target position; Accumulating the difference in the pressure fluctuation degree between the target position and each reference position to obtain the pressure fluctuation difference degree of the target position; The product value of the pressure fluctuation similarity and the pressure fluctuation difference is used as the part stability influence degree of the target position.

3. A high-precision clamping device for mechanical parts based on flexible force feedback according to claim 2, characterized in that: The step of obtaining the pressure fluctuation degree at each position of the bottom of the target suction cup includes: Extract extreme values ​​from the pressure data of all historical moments at the location of each pressure sensor at the bottom of the target suction cup, take two adjacent extreme values ​​as an extreme value group, and take the absolute value of the difference between the two extreme values ​​in each extreme value group as the pressure change amplitude of each extreme value group; The average value of the pressure variation amplitudes of all extreme value groups at each position at the bottom of the target suction cup is taken as the pressure fluctuation degree at each position at the bottom of the target suction cup.

4. The high-precision clamping device for mechanical parts based on flexible force feedback according to claim 1 is characterized in that: The obtaining of the real-time possibility of the parts falling of the clamping device comprises: At the bottom of the target suction cup, construct an initial vibration vector at the location of each pressure sensor, wherein the direction of the initial vibration vector at each location is the direction from the center of the target suction cup to each location, and the length of the initial vibration vector at each location is the part stability influence degree at each location at the bottom of the target suction cup; The positions of two mutually symmetrical pressure sensors on the bottom of the target suction cup are taken as the symmetrical position group of the target suction cup, the sum of the part stability influences of the two positions in each symmetrical position group is taken as the comprehensive influence of each symmetrical position group, and the two positions in the symmetrical position group with the largest comprehensive influence are taken as the key vibration positions of the bottom of the target suction cup; Obtain two suspected vibration vectors of the target suction cup according to the initial vibration vectors of all positions in a preset neighborhood of each key vibration position at the bottom of the target suction cup; Taking two mutually symmetrical suction cups as a symmetrical suction cup group, taking any one of the symmetrical suction cup groups as a target symmetrical suction cup group, and constructing a projection plane of the target symmetrical suction cup group, wherein the projection plane is perpendicular to a line connecting the midpoints of the two suction cups in the target symmetrical suction cup group and passes through the center point of the line; Projecting the two suspected vibration vectors of each suction cup in the target symmetrical suction cup group onto the projection plane to obtain two projection vectors of each suction cup in the target symmetrical suction cup group; A projection vector is selected from each of the two suction cups of the target symmetrical suction cup group, and the two selected projection vectors are used as a projection vector group. The angle between the two projection vectors in each projection vector group is used as a reference angle of each projection vector group, and the two projection vector groups with the smallest reference angles are used as reference projection vector groups of the target symmetrical suction cup group. Obtaining a part drop coefficient of the target symmetrical suction cup group according to the reference angle of each reference projection vector group of the target symmetrical suction cup group and a projection vector in each reference projection vector group; The average value of the part drop coefficients of all symmetrical suction cup groups is used as the real-time part drop possibility of the clamping device.

5. The high-precision clamping device for mechanical parts based on flexible force feedback according to claim 4 is characterized in that: The two suspected vibration vectors of the target suction cup are obtained as follows: The sum of the initial vibration vectors of all positions in the preset neighborhood of each key vibration position is used as the suspected vibration vector of the target suction cup.

6. A high-precision clamping device for mechanical parts based on flexible force feedback according to claim 4, characterized in that: The part drop coefficient of the target symmetrical suction cup group is obtained as follows: Performing negative correlation mapping on the average values ​​of the reference angles of the two reference projection vector groups of the target symmetrical suction cup group to obtain a first part drop evaluation value of the target symmetrical suction cup group; The sum of the two projection vectors in each reference projection vector group is used as the composite projection vector of each reference projection vector group, and the sum of the modulus lengths of the composite projection vectors of the two reference projection vector groups is used as the second part drop evaluation value of the target symmetrical suction cup group; The first part drop evaluation value and the second part drop evaluation value are integrated and normalized to obtain the part drop coefficient of the target symmetrical suction cup group.

7. The high-precision clamping device for mechanical parts based on flexible force feedback according to claim 1 is characterized in that: The step of obtaining the adjusted output power of the driving device for the mechanical claw at the next moment includes: The average value of the real-time pressure data of all the pressure sensors at the suction cup at the end of each mechanical claw is used as the real-time comprehensive pressure value of each mechanical claw; the real-time traction control weight of each mechanical claw is obtained according to the real-time comprehensive pressure value of each mechanical claw and the real-time possibility of the parts falling of the clamping device; Based on the calculation formula of the adjusted output power, the adjusted output power of the driving device for each mechanical claw at the next moment is obtained. The calculation formula of the adjusted output power is: P k ′ =w k ×P max ×Δt+P k Among them, P k ′ represents the adjustment output power of the drive device for the kth mechanical claw at the next moment; w k represents the real-time traction control weight of the k-th mechanical claw; P max represents the maximum output power of the driving device; Δt represents the sampling time interval of the pressure data; P k Represents the real-time output power of the driving device to the kth mechanical claw.

8. The high-precision clamping device for mechanical parts based on flexible force feedback according to claim 7 is characterized in that: The step of obtaining the real-time traction control weight of each mechanical claw comprises: Based on the calculation formula of the traction control weight, the real-time traction control weight of each mechanical claw is obtained. The calculation formula of the traction control weight is: w k =(1-norm(F k ))×U Among them, w k represents the real-time traction control weight of the k-th mechanical claw; F k It represents the real-time comprehensive pressure value of the k-th mechanical claw; U represents the real-time possibility of parts falling of the clamping device; norm() represents the normalization function.

9. The high-precision clamping device for mechanical parts based on flexible force feedback according to claim 1, characterized in that: The stopping time of the clamping action is obtained as follows: Input the probability of the parts falling off the clamping device at different times into the time series prediction algorithm, and output the predicted probability of the parts falling off at multiple future times; The stopping time of the clamping action is obtained based on the change in the predicted possibility of the part falling at each future time.

10. A high-precision clamping device for mechanical parts based on flexible force feedback according to claim 9, characterized in that: The step of obtaining the stopping time of the clamping action according to the change of the predicted possibility of the part falling at each future time comprises: Performing curve fitting on the predicted probability of the parts falling at all future moments to obtain a predicted fitting curve; On the prediction fitting curve, the sum of the slope at each future moment and the predicted probability of the part falling is used as a judgment parameter at each future moment; The future moment when the judgment parameter is the smallest is used as the stopping moment of the clamping action.

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