Grinding and measuring integrated self-adaptive variable-stiffness force-position combined grinding system

Abstract

The invention relates to the technical field of grinding systems, in particular to a grinding and measuring integrated self-adaptive variable stiffness force-position combined grinding system. The problems that according to an existing grinding technology, the comprehensive error between the grinding technology and the equipment tail end is large, part of grinding systems adopt the air bag technology, the response is slow, or a macro-micro composite motion platform lacks flexible buffering, and the inherent frequency cannot be matched with surface changes of machined workpieces in real time through manual adjustment are mainly solved. In order to solve the problems that grinding constant force control, response speed and real-time inherent frequency adjustment are seriously insufficient, the following technical scheme is provided: the device comprises an industrial robot, and the operating end of the industrial robot is provided with a connecting piece; and the rigid-flexible coupling force control module is arranged between the industrial robot and the connecting piece and used for achieving constant-force grinding and adjusting the inherent frequency in real time according to the change of the machined surface at the same time. Constant-force grinding, accurate displacement compensation and real-time rigidity adjustment are achieved, the grinding quality and efficiency are greatly improved, and the applicability of equipment in complex workpiece machining scenes is expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of grinding systems, and particularly to a grinding and measuring integrated adaptive variable stiffness force-position combined grinding system. Background Art

[0002] In the production of products such as sanitary wares, furniture, and hardware, the grinding process is a key link to ensure product quality. At the same time, force control of robots is extremely important for motion control and flexible control of human-machine interaction. However, there are many problems to be solved urgently in the current related technologies and equipment.

[0003] Existing robot operating systems are designed based on the rigid body hypothesis, without considering the elastic vibration of the robotic arm, and lacking grinding constant force control and human-machine interaction flexible control modules. The non-linear time-varying characteristics of the robot itself, combined with problems such as model parameter deviation, joint clearance, contact non-linearity, and elastic deformation of the robotic arm, result in a comprehensive error at the end of the 6-degree-of-freedom serial mechanism reaching 0.1 mm, which is difficult to meet the requirements of precise operation. Moreover, in the process of robot design, the multi-rigid body model ignores the elastic deformation of joints and connecting rods. When moving at high speed, the superposition of joint clearance and elastic deformation further increases the error.

[0004] Some existing grinding systems use airbag technology to maintain the grinding contact force. However, due to its gas characteristics, the response speed is slow when facing changes in the workpiece surface, about 90 ms, and it is impossible to ensure constant force control during grinding on a continuously and severely changing machining surface, affecting the machining effect. The macro-micro composite motion platform can combine the feedback of the force sensor and the servo motor drive, and performs excellently in positioning accuracy and moving response speed. For example, the moving response speed of some platforms can be controlled within 2 ms. However, for the situation where the surface curvature of the workpiece to be processed suddenly changes, it does not have a flexible buffering technology like the airbag technology, and impacts occur, resulting in the scrapping of the workpiece to be processed. Some platforms with the function of adjusting the natural frequency adjust it manually and cannot adjust it in real time according to the surface shape of the workpiece to be processed. The present invention makes full use of the buffering advantage of the flexible component in the rigid-flexible coupling platform, and through the same set of devices, realizes the integrated design of measurement and grinding only by switching the end tool. By pre-storing the contour curvature of the object to be processed during the measurement stage, and applying the innovative automatic adjustment technology of the natural frequency of the flexible component, the stiffness of the flexible component (adjusted by the natural frequency) is adaptively adjusted to the contour curvature of the workpiece to be processed.

[0005] It can be seen that the current grinding systems have serious deficiencies in aspects such as grinding constant force control, response speed, and real-time adjustment of the natural frequency according to changes in the processed surface. In view of this, the present invention proposes a grinding and measuring integrated adaptive variable stiffness force-position combined grinding system. Summary of the Invention

[0006] The object of the present invention is to address the problems in the background technology, where there is a large comprehensive error at the end of the existing grinding technology and equipment, the response of some grinding systems using airbag technology is slow, or the macro-micro composite motion platform lacks flexible buffering and the inherent frequency cannot be manually adjusted in real time to adapt to the surface changes of the workpiece being processed. There are serious deficiencies in constant force control, response speed, and real-time adjustment of the inherent frequency during grinding. Therefore, a grinding and measurement integrated adaptive variable stiffness force-position combined grinding system is proposed.

[0007] The technical solution of the present invention: A grinding and measurement integrated adaptive variable stiffness force-position combined grinding system, including an industrial robot, and a connecting piece is installed at the operating end of the industrial robot; a rigid-flexible coupling force control module is arranged between the industrial robot and the connecting piece, and the rigid-flexible coupling force control module is used to achieve constant force grinding and simultaneously adjust the inherent frequency in real time according to the changes of the surface being processed; a switching table, on which a force-position detection tool and a grinding head are installed; quick-connect female heads are respectively installed on the tops of the force-position detection tool and the grinding head, and a quick-connect male head matching with the quick-connect female head is arranged on the side of the connecting piece.

[0008] Optionally, the rigid-flexible coupling force control module includes: a mounting seat, which is arranged in a "U" shape, and baffles are fixedly connected to both ends of the mounting seat; a moving platform arranged on the open side of the mounting seat, and the moving platform is connected to the connecting piece; a transfer plate fixedly connected to the side of the mounting seat away from the connecting piece, and the transfer plate is installed at the operating end of the industrial robot; a driving mechanism installed in the mounting seat, and the driving mechanism is used to drive the moving platform to move; a limiting component arranged between the mounting seat and the moving platform, and the limiting component is used to ensure the smooth movement of the moving platform.

[0009] Optionally, the moving platform includes a moving frame, a flexible platform is arranged in the moving frame, the flexible platform is fixedly connected to the connecting piece, and multiple groups of parallel flexible hinges are connected between both sides of the flexible platform and the moving frame.

[0010] Optionally, the driving mechanism includes a servo motor installed in the mounting seat, the output end of the servo motor is fixedly connected to a threaded rod, a threaded sleeve is threadedly connected to the threaded rod, a transfer block is sleeved on the threaded sleeve, the transfer block is fixedly connected to the moving frame, the threaded rod is perpendicular to multiple groups of flexible hinges, and the axis of the threaded rod is parallel to the axis of the quick-connect male head.

[0011] Optionally, the limiting component includes two groups of slide rails fixedly connected to the side of the mounting seat close to the moving platform, multiple groups of sliders are slidably connected to both groups of slide rails, and multiple groups of sliders are fixedly connected to the moving frame.

[0012] Optionally, the rigid-flexible coupling force control module further includes a force sensor disposed between the moving frame and the flexible platform. The force sensor is arranged in parallel with the threaded rod. One end of the force sensor is fixedly connected to the moving frame, and the other end of the force sensor is fixedly connected to a connecting block, and the connecting block is installed on the side surface of the flexible platform.

[0013] Optionally, the rigid-flexible coupling force control module further includes adjustment mechanisms disposed on both sides of the flexible platform. The adjustment mechanism includes a deformation groove formed in the moving frame. The deformation groove is disposed on the side of the multi-group flexible hinges away from the flexible platform. An X-shaped bracket is arranged in the deformation groove, and a micro-push rod is installed on the inner wall of the deformation groove. The output end of the micro-push rod is rotatably connected to the X-shaped bracket.

[0014] Optionally, the rigid-flexible coupling force control module further includes a gravity sensor and a control board installed inside the mounting seat. The gravity sensor is electrically connected to the control board.

[0015] Optionally, it further includes a host computer and a servo driver. The force sensor, the micro-push rod, the gravity sensor, the host computer and the servo driver are all electrically connected to the control board.

[0016] Optionally, the force and position detection tool includes a housing, and a ball is installed at one end of the housing.

[0017] In summary, the present application includes at least one of the following beneficial technical effects:

[0018] In the present invention, the grinding force is monitored in real time through the force sensor. Through the cooperation of the control board and the servo driver, according to the real-time force value and the set grinding pressure value, the movement of the servo motor is accurately adjusted to achieve precise control of the grinding force;

[0019] Furthermore, the problem of friction dead zone is solved through the flexible hinge. Cooperating with the slide rail and slider limiting component, the positioning accuracy of the moving platform is greatly improved, and the displacement control reaches the nanometer level. In addition, the flexible hinge can also convert high-frequency vibration into low-frequency vibration, which is convenient for the application of control algorithms, stabilizes the grinding process, and comprehensively guarantees the grinding quality;

[0020] Furthermore, before grinding, the force and position information of the workpiece surface is collected by the force and position detection tool, which provides a basis for optimizing the grinding parameters. The force and position detection tool and the grinding head are quickly switched through the quick-connect male and female connectors, shortening the operation preparation time. And the control board can adjust the stroke of the micro-push rod according to the instructions of the host computer, change the natural frequency of the flexible hinge, so that the device can adapt to the surface characteristics of different workpieces, achieve the balance between grinding effect and efficiency, and significantly improve the operation adaptability and overall efficiency;

[0021] In summary, the present invention realizes constant-force grinding, precise displacement compensation, and real-time stiffness adjustment, greatly improving the grinding quality and efficiency, and expanding the applicability of the equipment in complex workpiece processing scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The structural schematic diagram of the integrated grinding and measurement adaptive variable stiffness force-position combined grinding system is given;

[0023] Figure 2 The structural schematic diagram of the rigid-flexible coupling force control module;

[0024] Figure 3 For Figure 2 The sectional structural schematic diagram;

[0025] Figure 4 The front view schematic diagram of the rigid-flexible coupling force control module;

[0026] Figure 5 For Figure 4 The enlarged schematic diagram at position A in

[0027] Figure 6 The explosion schematic diagram of the rigid-flexible coupling force control module;

[0028] Figure 7 The circuit schematic diagram;

[0029] Figure 8 The data processing flow chart.

[0030] Reference Signs:

[0031] 1. Industrial robot; 2. Connecting piece;

[0032] 3. Rigid-flexible coupling force control module; 31. Mounting seat; 311. Baffle;

[0033] 32. Moving platform; 321. Moving frame; 322. Flexible platform; 323. Flexible hinge;

[0034] 33. Adapter plate;

[0035] 34. Driving mechanism; 341. Servo motor; 342. Threaded rod; 343. Threaded sleeve; 344. Adapter block;

[0036] 35. Limiting component; 351. Slide rail; 352. Slide block;

[0037] 36. Force sensor; 361. Connecting block

[0038] 37. Adjusting mechanism; 371. Deformation groove; 372. X-shaped bracket; 373. Micro push rod;

[0039] 38. Gravity sensor; 39. Control board;

[0040] 4. Switching console;

[0041] 5. Force and position detection tool; 51. Housing; 52. Ball;

[0042] 6. Grinding head; 7. Female quick connector; 71. Male quick connector. Detailed implementation manner

[0043] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments.

[0044] Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention.

[0045] All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0046] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0047] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] Embodiment

[0049] As Figure 1As shown in the figure, the grinding and measuring integrated adaptive variable stiffness force-position combined grinding system proposed by the present invention includes an industrial robot 1. A connecting piece 2 is installed at the operating end of the industrial robot 1. The industrial robot 1 is a prior art and can drive the connecting piece 2 to move, so as to drive the grinding head 6 to move for grinding.

[0050] Specifically, please refer to Figure 2 , the above-mentioned grinding system includes a rigid-flexible coupling force control module 3 arranged between the industrial robot 1 and the connecting piece 2. The rigid-flexible coupling force control module 3 is used to realize constant force grinding and adjust the natural frequency in real time according to the change of the machined surface. The rigid-flexible coupling force control module 3 includes a mounting seat 31. The mounting seat 31 is arranged in a "U" shape, and baffles 311 are fixedly connected to both ends of the mounting seat 31.

[0051] In this embodiment, the above-mentioned rigid-flexible coupling force control module 3 includes a moving platform 32 arranged on the opening side of the mounting seat 31. The moving platform 32 is connected to the connecting piece 2. When the moving platform 32 moves, it drives the connecting piece 2 to move, so as to drive the force-position detection tool 5 or the grinding head 6 to move. The moving platform 32 includes a moving frame 321. A flexible platform 322 is arranged in the moving frame 321. The flexible platform 322 is fixedly connected to the connecting piece 2. A plurality of groups of flexible hinges 323 arranged in parallel are connected between both sides of the flexible platform 322 and the moving frame 321. The setting of the flexible hinges 323 effectively solves the problem of friction dead zone and greatly improves the positioning accuracy.

[0052] Furthermore, the above-mentioned rigid-flexible coupling force control module 3 includes an adapter plate 33 fixedly connected to the side of the mounting seat 31 away from the connecting piece 2. The adapter plate 33 is installed at the operating end of the industrial robot 1. After the industrial robot 1 is started, it drives the whole rigid-flexible coupling force control module 3 to move through the adapter plate 33.

[0053] Furthermore, as Figure 3As shown in the figure, the above-mentioned rigid-flexible coupling force control module 3 includes a driving mechanism 34 installed in the mounting base 31, and the driving mechanism 34 is used to drive the moving platform 32 to move. The driving mechanism 34 includes a servo motor 341 installed in the mounting base 31, and the position of the servo motor 341 is fixed. The output end of the servo motor 341 is fixedly connected to a threaded rod 342, and the servo motor 341 drives the threaded rod 342 to rotate after starting. A threaded sleeve 343 is threadedly connected to the threaded rod 342, and the threaded rod 342 drives the threaded sleeve 343 to move along the length direction of the threaded rod 342 when rotating. A transfer block 344 is sleeved on the threaded sleeve 343, and the transfer block 344 is fixedly connected to the moving frame 321. When the threaded sleeve 343 moves, it drives the moving frame 321 to move through the transfer block 344. The threaded rod 342 is vertically arranged with multiple flexible hinges 323, and the axis of the threaded rod 342 is parallel to the axis of the quick-connect male head 71, which is convenient to solve the problem of friction dead zone through the flexible hinges 323.

[0054] Furthermore, the above-mentioned rigid-flexible coupling force control module 3 includes a limiting component 35 arranged between the mounting base 31 and the moving platform 32, and the limiting component 35 is used to ensure the smooth movement of the moving platform 32. The limiting component 35 includes two groups of slide rails 351 fixedly connected to the side of the mounting base 31 close to the moving platform 32, and the positions of the slide rails 351 are fixed. Multiple slide blocks 352 are slidably connected to both groups of slide rails 351, and multiple slide blocks 352 are all fixedly connected to the moving frame 321. The slide blocks 352 and the moving frame 321 move synchronously, and the cooperation of the slide rails 351 and the slide blocks 352 makes the movement of the moving frame 321 smooth.

[0055] Furthermore, the above-mentioned rigid-flexible coupling force control module 3 further includes a force sensor 36 arranged between the moving frame 321 and the flexible platform 322. The force sensor 36 is arranged parallel to the threaded rod 342. One end of the force sensor 36 is fixedly connected to the moving frame 321, and the other end of the force sensor 36 is fixedly connected to a connecting block 361. The connecting block 361 is installed on the side surface of the flexible platform 322. The force sensor 36 is installed between the moving frame 321 and the flexible platform 322 through the connecting block 361, and at the same time, the actual force fluctuation during the movement of the flexible platform 322 is monitored through the force sensor 36.

[0056] Furthermore, please refer to Figure 4 and Figure 5, the above-mentioned rigid-flexible coupling force control module 3 further includes adjustment mechanisms 37 arranged on both sides of the flexible platform 322. The adjustment mechanisms 37 are used to adjust the natural frequency of the flexible hinges 323. The adjustment mechanisms 37 include deformation grooves 371 opened on the moving frame 321. The deformation grooves 371 are arranged on the side of multiple flexible hinges 323 away from the flexible platform 322. An X-shaped bracket 372 is arranged in the deformation grooves 371. A micro push rod 373 is installed on the inner wall of the deformation grooves 371. The output end of the micro push rod 373 is rotatably connected to the X-shaped bracket 372. By controlling the micro push rod 373 to generate different stress stiffening effects in the deformation grooves 371 under different strokes, the natural frequency of the flexible hinges 323 can be adjusted, that is, the stiffness of the rigid-flexible coupling force control module 3 is adjusted.

[0057] Specifically, as Figure 6 and Figure 7 shown, the above-mentioned grinding system further includes a host computer and a servo driver. The above-mentioned rigid-flexible coupling force control module 3 further includes a gravity sensor 38 and a control board 39 installed inside the mounting seat 31. The gravity sensor 38 is electrically connected to the control board 39. The force sensor 36, the micro push rod 373, the gravity sensor 38, the host computer and the servo driver are all electrically connected to the control board 39.

[0058] Among them, the above-mentioned grinding system includes a switching table 4. A force and position detection tool 5 and a grinding head 6 are installed on the switching table 4. The force and position detection tool 5 includes a housing 51. One end of the housing 51 is installed with a ball 52, which is convenient for smooth movement after contacting the surface of the object to be ground.

[0059] Furthermore, the above-mentioned grinding system further includes quick-connect female heads 7 respectively installed on the tops of the force and position detection tool 5 and the grinding head 6. A quick-connect male head 71 matching with the quick-connect female head 7 is arranged on the side of the connecting piece 2, which is convenient for quickly connecting the force and position detection tool 5 or the grinding head 6 through the quick-connect female head 7 and the quick-connect male head 71.

[0060] As Figure 8 shown, in this embodiment, when the force and position detection tool 5 slides on the workpiece contour, the gravity sensor 38 outputs the inclination angle when the robot changes its posture for the algorithm to compensate for the gravity deviation. The encoder of the servo driver transmits the displacement situation to the control board 39, and the force sensor 36 transmits the actual force fluctuation situation to the control board 39. The control board 39 then transmits the displacement information and the force information to the host computer software in the host computer through the RS485 bus at a period of 10 ms. This process is mainly for raw data acquisition and there is no specific formula calculation.

[0061] Input vector calculation Adaptor dynamic dimensionality reduction technology related

[0062] The known force sensor 36 has a range of 0 - 50N and an accuracy of ±0.5% FS; the rigid-flexible coupling force control module 3 has a displacement feedback range of 0 - 230mm and a resolution of 10μm; the time window T = 50s (sampling rate of 100Hz). Assume the input vector is S t , which is composed of the data of the force sensor 36 and the displacement sensor data in a time series, S t = [f t-n ,…, f t , d t-n ,…, d t , where f represents the force value, d represents the displacement value, and n is related to the time window.

[0063] Encoder calculation

[0064] h1 = ReLU(W1S t + b1) (W1 ∈ R 64×2T , b1 ∈ R 64 )

[0065] h2 = ReLU(W2h1 + b2) (W2 ∈ R 32×64 , b2 ∈ R 32 )

[0066] z = W3h2 + b3 (z ∈ R d , d = 8)

[0067] In the above two equations, h1 and h2 are two core intermediate states of the classification model, and their functions are directly related to feature abstraction and decision generation in the process classification task of industrial robots. h1 performs preliminary feature separation on the implicit features such as the force detected by the force control sensor and the displacement of the servo motor; h2 realizes the generation of multi-class decision boundaries and constructs a classification hyperplane.

[0068] First, after multiplying the input vector S t by the weight matrix W1 and adding the bias b1, h1 is obtained through the ReLU activation function; then, h1 is multiplied by W2 and added the bias b2, and then h2 is obtained through ReLU activation; finally, h2 is multiplied by W3 and added the bias b3 to obtain the low-dimensional feature vector z.

[0069] Classifier calculation

[0070] y = Softmax(W c z + b c )(W c ∈ R C×d , C = 4)

[0071] The low-dimensional feature vector z is multiplied by the weight matrix W c and added the bias b cAfter that, the result is converted into a probability distribution y belonging to 4 categories through the Softmax function.

[0072] Calculation of the combined loss function

[0073] L = 0.7L cls + 0.2L recon + 0.1L ortho

[0074] Among them, L cls is the cross-entropy of the classification loss, L recon is the cross-entropy of the reconstruction loss, L ortho is the cross-entropy of the orthogonal constraint.

[0075] Calculation of the cross-entropy of the classification loss

[0076]

[0077] Among them, y c is the one-hot encoding of the true label (ground-truth label), is the probability that the model predicts the sample to belong to categories C1 - C4 (normalized by Softmax), and the error of classification is measured by calculating the cross-entropy between the true label and the predicted probability.

[0078] Calculation of the reconstruction loss (MSE)

[0079]

[0080] After reconstructing the original input data or related features, calculate the reconstructed value and the mean square error with the original value x i to measure the accuracy of the reconstruction.

[0081] Calculation of the orthogonal constraint

[0082]

[0083] By calculating the Frobenius norm of the product of the transpose of the weight matrix W2 of the dimensionality reduction layer and itself and the identity matrix I, feature collapse is prevented.

[0084] Calculation of the grinding force control in the grinding stage

[0085] Read the converted voltage value of the force sensor 36, and obtain the real-time force value F after calculation and conversion real . Compare F real with the set grinding pressure value F set :

[0086] When F real > F setWhen it is time, the control board 39 sends a signal to the servo driver to control the servo motor 341 to retract backward to reduce the grinding force. The relationship between the specific control signal and the motor retraction amount is determined by the internal parameters of the servo driver. Assuming the control signal is U, there is a functional relationship between the motor retraction amount Δl and U, Δl = k1U (k1 is the proportionality coefficient), and U is related to the difference between F real -F set For example, U = k2(F real -F set )(k2 is another proportionality coefficient).

[0087] When F real <F set , the control board 39 sends a signal to the servo driver to control the servo motor 341 to push forward to increase the grinding force. The principle is the same as above, except that the motor movement direction is opposite.

[0088] Calculation of the natural frequency adjustment of the flexible hinge 323

[0089] The control board 39 adjusts the PWM signal according to the f(X) value transmitted from the host computer. Let the duty cycle of the PWM signal be D, and there is a mapping relationship between D and f(X), D = g(f(X)). The PWM signal passes through the voltage amplification circuit to make the two-way output voltage V controllable within 0 - 24V. There is a functional relationship between V and D, V = h(D). The voltage V controls the stroke L of the micro-push rod 373. There is a functional relationship between L and V, L = m(V). The deformation groove 371 produces different stress stiffening effects under different strokes L of the micro-push rod 373, thereby adjusting the natural frequency w of the flexible hinge 323. There is a functional relationship between w and L, w = n(L).

[0090] D: Duty cycle; D = g(f(X)), X is the set natural frequency value, f(X) is the voltage digital value corresponding to a certain set natural frequency. This system uses a 12-bit DA conversion system. The range of D is the analog quantity from 0 to 1, corresponding to the digital quantity from 0 to 4095 (0 - 2 12 -1). There is a functional relationship between V and D, V = h(D). The range of D is from 0 to 1, corresponding to the range of V from 0 to 24V. The voltage V controls the stroke of the micro-push rod 373, and its horizontal displacement range is 0 - 5mm. When the micro-push rod 373 generates a contact force with the deformation groove 371, different stress tempering effects will be produced, thereby adjusting the natural frequency w of the flexible hinge 323. There is a functional relationship between w and L, w = n(L). The change of L makes w adjustable between 20 - 150Hz.

[0091] In this embodiment, before grinding the special-shaped workpiece, the industrial robot 1 moves the connecting piece 2 to the position where the switching table 4 is located. The industrial robot 1 sends an instruction to the host computer software in the host computer through the industrial Ethernet, and the host computer software sends an instruction to the control board 39 through the RS485 bus. The control board 39 sets the force sensor 36 to the detection pressure mode. And the industrial robot 1 installs the force and position detection tool 5 on the side of the connecting piece 2 through the quick-connect male head 71 and the quick-connect female head 7. The industrial robot 1 drives the force and position detection tool 5 to move according to the preset grinding trajectory, and the force and position detection tool 5 can smoothly slide on the workpiece contour through the ball 52. During the sliding process, in order to maintain a constant force, the flexible platform 322 will perform a telescopic movement along the direction of the threaded rod 342. During the movement, the encoder of the servo driver will transmit the displacement of the force and position detection tool 5 to the control board 39. The control board 39 transmits the displacement information and the force information to the host computer software in the host computer through the RS485 bus, with a period of 10 ms. This process realizes the comprehensive acquisition of the force and position information on the workpiece surface, providing data support for the parameter optimization of the subsequent grinding operation.

[0092] After that, the force and position detection tool 5 is switched to the grinding head 6 through the quick-connect female head 7 and the quick-connect male head 71, and the industrial robot 1 drives the grinding head 6 to perform grinding. During the grinding process, the industrial robot 1 drives the grinding head 6 along the established trajectory. The grinding head 6 rotates at a high speed while contacting the workpiece to be processed. The grinding force it receives is transmitted to the force sensor 36 through the flexible platform 322, the flexible hinge 323, the moving frame 321, and the connecting block 361. The control board 39 reads the converted voltage value, and after calculation and conversion, it is transformed into the real-time force value of the rigid-flexible coupling force control module 3. The real-time force value is compared with the set grinding pressure value. When the real-time force value exceeds the set grinding pressure value, the control board 39 sends a signal to the servo driver to control the servo motor 341 to retract backward and reduce the grinding force; when the real-time force value is lower than the set grinding pressure value, the control board 39 sends a signal to the servo driver to control the servo motor 341 to push forward and increase the grinding force. The response time between the control board 39, the servo driver, and the servo motor 341 is within 2 ms, ensuring the fast response of the rigid-flexible coupling force control module 3 to achieve constant force-displacement control during the grinding process. On the other hand, the use of the flexible hinge 323 can overcome the friction dead zone of the slide rail 351, and through the macro-micro combined movement, the displacement control of the rigid-flexible coupling force control module 3 can be accurate to the nanometer level. The use of the flexible hinge 323 can convert the high-frequency vibration when the grinding head 6 contacts the processed surface into low-frequency vibration through elastic deformation, facilitating the use of the control algorithm and further improving the stability and accuracy of the grinding operation.

[0093] The above specific embodiments are merely alternative embodiments of the present invention. Based on the technical solution of the present invention and the relevant revelations of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. Grinding and measuring integrated adaptive variable stiffness force and position combined grinding system, characterized by: Comprising: An industrial robot (1), with a connecting piece (2) installed at the operating end of the industrial robot (1); A rigid-flexible coupling force control module (3) arranged between the industrial robot (1) and the connecting piece (2), and the rigid-flexible coupling force control module (3) is used to achieve constant force grinding and adjust the natural frequency in real time according to the change of the machined surface; A switching table (4), on which a force-position detection tool (5) and a grinding head (6) are installed; Quick-connect female connectors (7) respectively installed at the tops of the force-position detection tool (5) and the grinding head (6), and a quick-connect male connector (71) matching with the quick-connect female connector (7) is arranged on the side of the connecting piece (2).

2. The grinding and measuring integrated adaptive variable stiffness force-position combined grinding system according to claim 1 is characterized in that: The rigid-flexible coupling force control module (3) includes: A mounting seat (31), the mounting seat (31) is arranged in a "U" shape, and baffles (311) are fixedly connected to both ends of the mounting seat (31); A moving platform (32) arranged on one side of the opening of the mounting seat (31), and the moving platform (32) is connected to the connecting piece (2); An adapter plate (33) fixedly connected to the side of the mounting seat (31) away from the connecting piece (2), and the adapter plate (33) is installed at the operating end of the industrial robot (1); A driving mechanism (34) installed in the mounting seat (31), and the driving mechanism (34) is used to drive the moving platform (32) to move; A limiting component (35) arranged between the mounting seat (31) and the moving platform (32), and the limiting component (35) is used to ensure the smooth movement of the moving platform (32).

3. The grinding and measuring integrated adaptive variable stiffness force-position combined grinding system according to claim 2 is characterized in that: The moving platform (32) includes a moving frame (321), a flexible platform (322) is arranged in the moving frame (321), the flexible platform (322) is fixedly connected to the connecting piece (2), and a plurality of groups of parallel flexible hinges (323) are connected between both sides of the flexible platform (322) and the moving frame (321).

4. The grinding and measuring integrated adaptive variable stiffness force-position combined grinding system according to claim 3 is characterized in that: The driving mechanism (34) includes a servo motor (341) installed in the mounting seat (31), the output end of the servo motor (341) is fixedly connected with a threaded rod (342), a threaded sleeve (343) is threadedly connected to the threaded rod (342), an adapter block (344) is sleeved on the threaded sleeve (343), the adapter block (344) is fixedly connected to the moving frame (321), the threaded rod (342) is perpendicular to the plurality of groups of flexible hinges (323), and the axis of the threaded rod (342) is parallel to the axis of the quick-connect male connector (71).

5. The grinding and measuring integrated adaptive variable stiffness force-position combined grinding system according to claim 4 is characterized in that: The limiting component (35) includes two groups of slide rails (351) fixedly connected to the side of the mounting seat (31) close to the moving platform (32), a plurality of groups of sliders (352) are slidably connected to both groups of slide rails (351), and the plurality of groups of sliders (352) are all fixedly connected to the moving frame (321).

6. The grinding and measuring integrated adaptive variable stiffness force-position combined grinding system according to claim 5 is characterized in that: The rigid-flexible coupling force control module (3) further comprises a force sensor (36) arranged between the moving frame (321) and the flexible platform (322); the force sensor (36) is arranged in parallel with the threaded rod (342); one end of the force sensor (36) is fixedly connected to the moving frame (321); the other end of the force sensor (36) is fixedly connected to a connecting block (361); and the connecting block (361) is mounted on a side of the flexible platform (322).

7. The grinding and measuring integrated adaptive variable stiffness force-position combined grinding system according to claim 6 is characterized in that: The rigid-flexible coupling force control module (3) further comprises an adjustment mechanism (37) arranged on both sides of the flexible platform (322), the adjustment mechanism (37) comprising a deformation groove (371) provided on the movable frame (321), the deformation groove (371) being arranged on a side of the plurality of flexible hinges (323) away from the flexible platform (322), an X-shaped bracket (372) being arranged in the deformation groove (371), a micro push rod (373) being installed on the inner wall of the deformation groove (371), and an output end of the micro push rod (373) being rotationally connected to the X-shaped bracket (372).

8. The grinding and measuring integrated adaptive variable stiffness force-position combined grinding system according to claim 7 is characterized in that: The rigid-flexible coupling force control module (3) further comprises a gravity sensor (38) and a control board (39) mounted on the inner side of the mounting seat (31); the gravity sensor (38) is electrically connected to the control board (39).

9. The grinding and measuring integrated adaptive variable stiffness force-position combined grinding system according to claim 8, characterized in that: It also includes a host computer and a servo driver. The force sensor (36), the micro push rod (373), the gravity sensor (38), the host computer and the servo driver are all electrically connected to the control board (39).

10. The grinding and measuring integrated adaptive variable stiffness force-position combined grinding system according to claim 9, characterized in that: The force position detection tool (5) comprises a housing (51), and a ball (52) is mounted on one end of the housing (51).

Images