A vibration suppression system for industrial robot cutting and a vibration reduction method thereof

Abstract

The application discloses a vibration suppression system for industrial robot cutting and a damping method thereof, and relates to the field of vibration damping technology for industrial robot cutting processing. The vibration suppression system for industrial robot cutting comprises a robot body, a cutting tool, a piezoelectric active damping device and a piezoelectric control device. The damping method comprises the following steps: detecting the vibration acceleration and displacement of the tool detection point through the acceleration displacement sensor; inputting an alternating voltage from the outside to change the thrust output of the piezoelectric active damping device. According to the changes of the external excitation and the vibration of the end tool in the cutting process of the robot, the output thrust of the ring-shaped piezoelectric ceramic stack actuator in the end tool handle of the robot can be conveniently and timely adjusted, so that the torque corresponding to the cutting force is output in the processing process, active damping with high efficiency and adaptability is realized, and the vibration of the robot in the cutting process is effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of industrial robot technology, specifically to a vibration suppression system and vibration reduction method for industrial robot cutting. Background Technology

[0002] Industrial robots are mechanical devices used in industrial fields, possessing automation capabilities and multi-joint motion capabilities. They can use internal energy and control systems to complete various industrial processing and manufacturing tasks. With the improvement of productivity and technological level, the uses of industrial robots are no longer limited to simple operations such as handling, palletizing, spraying, and welding, but are increasingly being applied to complex processing and manufacturing processes. Compared with traditional human labor and CNC machine tool processing, industrial robots have the following advantages: 1) Better spatial accessibility, able to cover a larger operating space; 2) High degree of flexibility, with different degrees of freedom of industrial robots that can be selected to adapt to different usage conditions; 3) High manufacturing and processing efficiency and better adaptability; 4) Ability to work continuously in harsh processing environments.

[0003] Therefore, industrial robots are increasingly being used in manufacturing to replace manual labor and machine tools in tasks such as drilling, milling, planing, grinding, and cutting. The development of industrial robots has brought greater efficiency and flexibility to the manufacturing industry. However, industrial robots are susceptible to unstable cutting forces and disturbances during machining processes. Furthermore, their cantilever-beam-like structure, with inherent rigidity only about 1 / 50th that of machine tools, makes them prone to significant machining vibrations, which can affect workpiece quality and even damage the robot itself. Therefore, new machining devices and vibration reduction methods are urgently needed to control the unavoidable vibrations during robot machining.

[0004] Currently, the most common methods for vibration reduction in industrial robots are active vibration reduction, semi-active vibration reduction, and passive vibration reduction. Active vibration reduction is a method that reduces structural vibration through active control technology. It utilizes sensors to monitor structural vibration in real time and applies control systems and actuators to actively intervene in the vibration state of the structure. Active vibration reduction can adjust system parameters or apply control forces in real time to reduce vibration amplitude and frequency. Active vibration reduction methods can include active mass adjustment, electromagnetic force excitation, and piezoelectric material control. Active vibration reduction has adaptability and high vibration reduction effect. Semi-active vibration reduction is a vibration reduction method between active and passive vibration reduction. It uses passive vibration dampers combined with some active control means to achieve the purpose of reducing structural vibration. Semi-active vibration dampers monitor vibration through sensors and use control systems to adjust the characteristics of the dampers to obtain better vibration reduction effects. Compared with passive vibration reduction, semi-active vibration reduction has higher adaptability and adjustability, but compared with active vibration reduction, its control means and complexity are lower. Passive vibration reduction is a method that uses vibration dampers to absorb or disperse vibration energy. Passive vibration dampers, depending on their design principles and operating methods, can provide functions such as damping, spring effect, and mass distribution to reduce the vibration amplitude of a structure. Common passive vibration dampers include mechanical dampers, dampers, springs, and damping fluids. Passive vibration dampers do not require complex sensors and control systems, resulting in lower costs and maintenance requirements. However, the vibration reduction effect of passive vibration dampers is significantly affected by structural characteristics and additional loads, and their reduction effect is more limited compared to active and semi-active vibration damping.

[0005] Chinese patent CN110829892A discloses a "piezoelectric energy-absorbing vibration damping device," which specifically discloses a device that converts vibration energy into electrical energy to achieve vibration damping. However, because piezoelectric energy-absorbing vibration damping achieves damping by converting vibration energy into other forms of energy, its control precision is relatively low. In contrast, piezoelectric active vibration damping can achieve higher precision vibration control by precisely controlling the application of the electric field and the deformation of the piezoelectric material. Moreover, piezoelectric energy-absorbing vibration damping cannot achieve frequency adjustment; it is usually designed based on a specific frequency. However, piezoelectric active vibration damping can control various vibration types at different frequencies based on real-time vibration characteristics and vibration frequency.

[0006] For example, Chinese patent CN116551047A discloses "A Force-Measuring Vibration-Damping Tool Holder Based on Piezoelectric Effect," which specifically discloses an active and passive vibration-damping tool holder integrating piezoelectric vibration detection and control, capable of remotely detecting the vibration generated by the tool holder during the cutting process in real time. The existing technology using piezoelectric sensors and actuators not only makes the structure more complex, increases manufacturing costs, and lengthens the production cycle, making inspection and replacement during use inconvenient, but also, because the tool itself is subjected to a complex time-varying cutting force during cutting, the cutting force detected by the piezoelectric sensor does not correspond to the real-time cutting force experienced by the tool. Therefore, piezoelectric vibration control can introduce significant errors, potentially even exacerbating tool vibration. The aforementioned technology places the active piezoelectric vibration damping device inside the tool holder, significantly reducing the rigidity of the tool holder structure, which can prevent the tool holder from meeting high-speed operation requirements.

[0007] For example, Chinese patent CN213288844U discloses a "machine tool vibration damping tool holder," which specifically discloses a method of reducing the transmission of mechanical energy of vibration generated by the tool head during cutting by opening a receiving groove at the front end of the tool body and fixing a vibration core in the receiving groove. The vibration core's damping effect reduces the vibration of the tool head during cutting. Currently, passive vibration damping, such as traditional damping vibration damping, is the most widely used method for vibration reduction in machining. Active vibration damping requires external control and energy supply, making the process more complex. However, the vibration reduction effect of passive vibration damping is far less significant than that of active vibration damping, and it cannot be adjusted accordingly to the complex and ever-changing dynamic environmental excitation during robot cutting, resulting in low vibration reduction efficiency.

[0008] The common shortcomings of the aforementioned existing technologies are: few tool holders can apply piezoelectric active vibration damping devices to vibration reduction in industrial robot cutting processes, and most current vibration damping tool holders are still designed for traditional CNC machine tool processing. However, there are significant differences between CNC machine tool processing and industrial robot processing. Industrial robots have lower stiffness than machine tools, and therefore face more complex vibration situations. Summary of the Invention

[0009] The purpose of this invention is to provide a vibration suppression system and vibration reduction method for industrial robot cutting, so as to solve the problems mentioned in the background art.

[0010] To address the aforementioned technical problems, this invention provides the following technical solution: a vibration suppression system for industrial robot cutting, comprising a robot body, a cutting tool, a piezoelectric active vibration damping device, and a piezoelectric control device; one end of the robot body is equipped with a robot end effector, and the cutting tool is connected to the robot end effector via a customized tool holder; the piezoelectric active vibration damping device is mounted and connected to the spindle of the robot end effector; the piezoelectric active vibration damping device includes a stiffness enhancement module, a conductive slip ring, and a ring-shaped piezoelectric ceramic stacked actuator, wherein the stiffness enhancement module is sleeved... On the outside of the customized tool holder, the conductive slip ring is sleeved on the outside of the stiffness enhancement module, and the annular piezoelectric ceramic stacked actuator is distributed around the customized tool holder. The annular piezoelectric ceramic stacked actuator is connected to the inner ring of the conductive slip ring, and the outer ring of the conductive slip ring is connected to the piezoelectric control device. The alternating voltage output of the piezoelectric control device is adjusted according to the vibration under different external excitation conditions, thereby controlling the alternating voltage of the electrodes inside the annular piezoelectric ceramic stacked actuator, changing the thrust and displacement generated therefrom, so as to counteract the vibration generated by the tool during the machining process.

[0011] Furthermore, the annular piezoelectric ceramic stacked actuators are distributed in an equally spaced annular array, and are located on the outside of the custom tool holder. The lower end of each annular piezoelectric ceramic stacked actuator is provided with a hemispherical hinge, which fits into the groove of the custom nut. The annular piezoelectric sheet inside the annular piezoelectric ceramic stacked actuator is made of piezoelectric ceramic. The upper end face between the upper boss of the stiffness enhancement module and the conductive slip ring is on the same plane, and the stiffness enhancement module and the custom tool holder are interference fit.

[0012] Furthermore, the piezoelectric active vibration damping device also includes a ring piezoelectric ceramic stack actuator pre-tightening fixing device. The upper end face of the ring piezoelectric ceramic stack actuator pre-tightening fixing device is attached to the stiffness enhancement module. Several ring piezoelectric ceramic stack actuator inner ring support shafts are provided around the customized tool holder on the concave bottom surface of the ring piezoelectric ceramic stack actuator pre-tightening fixing device. The ring piezoelectric ceramic stack actuator pre-tightening sleeve in the ring piezoelectric ceramic stack actuator pre-tightening fixing device is bonded together with the ring piezoelectric ceramic stack actuator.

[0013] Furthermore, a stiffness enhancement module is fitted on the outer side of the custom tool holder. Below the stiffness enhancement module is a pre-tightening fixing device for the annular piezoelectric ceramic stacked actuator. The inner rings of the four annular piezoelectric ceramic stacked actuators are fitted with an inner ring support shaft. The outer rings of the annular piezoelectric ceramic stacked actuators are connected to the pre-tightening fixing device through an annular piezoelectric ceramic stacked actuator protection device. The lower end of the annular piezoelectric ceramic stacked actuator is in direct contact with the groove of the custom nut through a semi-spherical hinge. The inner ring of the conductive slip ring is fixed to the end of the custom tool holder through an M3 connecting bolt, and the outer ring is fixed to the spindle of the robot end effector through a lug.

[0014] Furthermore, the overall length of the custom tool holder is relatively long, which affects its rigidity and thus has a significant impact on machining. Therefore, the rigidity enhancement module is added to improve its overall rigidity. The rigidity enhancement module has bosses on both the upper and lower end faces. The upper boss and the conductive slip ring are clearance fit, and their upper end faces are on the same plane. The lower boss has four M3 threaded holes for fixing to the annular piezoelectric ceramic stacked actuator pre-tightening fixing device with M3 connecting bolts. The inner ring of the rigidity enhancement module and the custom tool holder are interference fit.

[0015] Furthermore, the upper end face of the pre-tightening fixing device of the annular piezoelectric ceramic stack actuator is in direct contact with the bottom surface of the lower boss of the stiffness enhancement module, and the two are fixed together by bolts. The annular piezoelectric ceramic stack actuator pre-tightening fixing device has a recessed platform in the middle. On the bottom surface of the recessed platform, there are four symmetrically distributed annular piezoelectric ceramic stack actuator inner ring support shafts around the customized tool holder. Each annular piezoelectric ceramic stack actuator inner ring support shaft is fixed to the bottom surface of the boss by M3 bolts symmetrically connected on the left and right sides. Because the annular piezoelectric ceramic stack actuator needs to be pre-tightened during installation, that is, 10% of the maximum thrust that the annular piezoelectric ceramic stack actuator can generate, the M3 bolt can be used as a fixed connection bolt and also as a pre-tightening bolt of the annular piezoelectric ceramic stack actuator, directly contacting the annular piezoelectric ceramic stack actuator pre-tightening sleeve, and then converting the thrust applied to the pre-tightening sleeve into pre-tightening force. The inner ring support shafts of the annular piezoelectric ceramic stack actuator are arranged in a ring array at 90° intervals, and the annular piezoelectric ceramic stack actuator pre-tightening sleeve in the annular piezoelectric ceramic stack actuator pre-tightening fixing device is directly bonded to the annular piezoelectric ceramic stack actuator.

[0016] Furthermore, the four annular piezoelectric ceramic stacked actuators are arranged in a ring array at 90° intervals on the outside of the custom tool holder, enabling them to generate corresponding thrust in any direction on the cutting force surface to cancel out torque. The lower end of each annular piezoelectric ceramic stacked actuator has a hemispherical hinge that directly engages with the groove of the custom nut through preload. Each single layer of the annular piezoelectric ceramic stacked actuator is made of PZT-5 piezoelectric ceramic, sintered. Electrodes are laid between each layer of annular piezoelectric sheets, and these electrodes must be insulated from each other. 2mm thick insulating ceramic is laid at both ends inside the annular piezoelectric ceramic stacked actuator for insulation protection.

[0017] Furthermore, the conductive slip ring is a sliding contact made of graphite, responsible for conducting current and analyzing control signals between the rotating and stationary components. A wire is led out from the annular piezoelectric ceramic stack actuator and directly connected to the inner ring terminal of the conductive slip ring, while its outer ring terminal is connected to an external voltage amplifier. The tool is secured to the tool holder by the spring collet and the custom nut.

[0018] Furthermore, the piezoelectric control device includes an acceleration displacement sensor, a DSP signal controller, a voltage amplifier, and a dynamic testing and analysis system. The acceleration displacement sensor is connected to the dynamic testing and analysis system via a signal line, and the output of the voltage amplifier is connected to the ring-shaped piezoelectric ceramic stack actuator. The acceleration displacement sensor is mounted on the robot's cutting end spindle near the customized tool via a magnet mount, and the X, Y, and Z directions of the acceleration displacement sensor are aligned with the base coordinates of the robot body. The acceleration displacement sensor is used to detect the vibration signal of the customized tool during machining in real time and transmits the vibration signal to the dynamic testing and analysis system. The dynamic testing and analysis system converts the vibration signal into a frequency signal, i.e., the vibration frequency of the cutting process. The DSP signal controller processes the frequency signal and finally outputs a corresponding AC voltage to the voltage amplifier. The voltage amplifier amplifies the voltage signal processed by the DSP signal controller, enabling the ring-shaped piezoelectric ceramic stack actuator to output a corresponding thrust under the voltage input to the voltage amplifier.

[0019] A vibration reduction method for a vibration suppression system used in industrial robot cutting, the vibration reduction method specifically includes the following steps: Step S1: Detect the vibration acceleration and displacement of the tool detection point on the customized tool during the cutting process of the robot body using the acceleration and displacement sensor; Step S2: Based on the vibration of the tool detection point, the input alternating voltage of the piezoelectric active vibration damping device is controlled externally, thereby changing the thrust output of the piezoelectric active vibration damping device.

[0020] Step S1 includes: Step S101: Determine the relationship between the vibration acceleration in the X and Y directions and the vibration acceleration in the Z direction of the current tool detection point, as well as the vibration displacement in the X and Y directions and the vibration displacement in the Z direction of the tool vibration detection point. The determination results include condition A and condition B. Condition A corresponds to processing flow A'; condition B corresponds to processing flow B'. Step S102: After obtaining the judgment result as either condition A or condition B, determine the relationship between the maximum thrust that the ring piezoelectric ceramic stacked actuator can generate and the expected thrust. The relationship conditions include condition C and condition D; where condition C corresponds to processing flow C' and condition D corresponds to processing flow D'.

[0021] Condition A is: when the vibration acceleration of the tool detection point in the X and Y directions during the robot cutting process is greater than or equal to the vibration acceleration in the Z direction, and the vibration displacement of the tool vibration detection point in the X and Y directions is greater than or equal to the vibration displacement in the Z direction, the processing flow A' is executed. The specific operation of process A' is as follows: Based on the vibration balance condition analysis of the cutting tool, the expected output thrust of a set of annular piezoelectric ceramic stacked actuators in the X or Y direction is calculated by the following formula: ; in The distance between the center of the customized nut and the center of the tool tip; The distance between the center of the custom nut and the point of action of the annular piezoelectric ceramic stack actuator; The radial cutting force acting on the tool at this moment is obtained by processing the acceleration in the X or Y direction; Determine the relationship between the maximum thrust that the toroidal piezoelectric ceramic stack actuator can generate and the desired thrust. The relationship conditions include condition C, corresponding to processing flow C'; and condition D, corresponding to processing flow D'.

[0022] Condition B: When the vibration acceleration in the X and Y directions of the tool detection point during robot cutting is less than the vibration acceleration in the Z direction, and the vibration displacement in the X and Y directions of the tool vibration detection point is less than the vibration displacement in the Z direction, process flow B' is executed. Based on the balance condition analysis of the cutting tool, the expected output thrust of the four annular piezoelectric ceramic stack actuators is calculated by the following formula: ; In the formula For the desired thrust, The applied voltage amplitude, This represents the equivalent mechanical stiffness of the toroidal piezoelectric ceramic stack actuator. The equivalent electrical stiffness of the toroidal piezoelectric ceramic stacked actuator; Determine the relationship between the maximum thrust range that the toroidal piezoelectric ceramic stack actuator can generate and the desired thrust. The relationship conditions include condition C, corresponding to processing flow C'; and condition D, corresponding to processing flow D'.

[0023] The condition C is: during robot cutting, the expected thrust of the ring piezoelectric ceramic stacked actuator is within the output thrust range. The output thrust range is determined by the selected model of the actual ring piezoelectric ceramic stacked actuator, and its maximum value can reach about 5700N. Then, the processing flow C' is executed. The process C' is as follows: Adjust the alternating voltage input of the piezoelectric controller to the ring piezoelectric ceramic stack actuator so that the output thrust of the ring piezoelectric ceramic stack actuator is equal to the desired thrust.

[0024] The condition D is: when the desired thrust of the vibration damping device is outside the above-mentioned output thrust range during robot cutting, the processing flow D' is executed. The process D' is as follows: Adjust the model of the annular piezoelectric ceramic stack actuator in the piezoelectric active vibration damping device, and select an annular piezoelectric ceramic stack actuator model that can output the desired thrust under ideal conditions, until the tool vibration is reduced and meets the requirements.

[0025] Compared with the prior art, the beneficial effects achieved by the present invention are: This invention, combined with appropriate measurement methods and vibration reduction techniques, allows the piezoelectric active vibration reduction device to conveniently adjust the output thrust of the annular piezoelectric ceramic stacked actuator in the robot's end-effector in real time, based on changes in external excitation and end-effector vibration during the robot's cutting process. This results in the output of force and torque corresponding to the cutting force during the machining process, achieving efficient and adaptive active vibration reduction and effectively reducing robot cutting vibration.

[0026] The piezoelectric active vibration damping device in this invention is centrally symmetrical in structure, with the annular piezoelectric ceramic stack actuators arranged in a ring array. It can output thrust to cancel the cutting force in various directions during the cutting process. At the same time, while canceling the torque of the cutting force in the X and Y planes, the thrust output by the piezoelectric stack can also cancel the axial cutting force to a certain extent, thereby achieving multi-directional cutting vibration reduction. This maximizes energy utilization during the vibration reduction process.

[0027] In this invention, the piezoelectric active vibration damping device uses piezoelectric ceramics as the carrier for generating thrust. It has high sensitivity and accuracy in generating thrust by utilizing the inverse piezoelectric effect. The piezoelectric ceramics can adjust the corresponding voltage and work according to the vibration. Moreover, the piezoelectric ceramics have a wide signal transmission frequency range, from several kilohertz to several megahertz, and can be applied to a wide range of processing applications.

[0028] In this invention, the piezoelectric active vibration damping device and the tool holder are used together and can be separated. The manufacturing and dynamic balancing requirements are low, and it is very convenient when it is necessary to replace the corresponding ring piezoelectric ceramic stacked actuator. Different tools can also be selected for processing according to different processing occasions. It is not easy to cause collateral damage to the piezoelectric active vibration damping structure, which is conducive to the long-term use of the piezoelectric vibration damping device. In addition, the piezoelectric active vibration damping device is modularly designed, which is easy to install and disassemble, and facilitates the replacement of the piezoelectric ring piezoelectric ceramic stacked actuator. Attached Figure Description

[0029] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 is a schematic diagram of the installation and principle of the device of the present invention; Figure 2 is a cross-sectional view of a piezoelectric active vibration damping device for vibration suppression in industrial robot cutting processes according to the present invention; Figure 3 This is an isometric view of a piezoelectric active vibration damping device for vibration suppression in industrial robot cutting processes according to the present invention; Figure 4 This is a block diagram illustrating the working principle of a piezoelectric active vibration damping device for vibration suppression in industrial robot cutting processes according to the present invention. Figure 5 This is a schematic diagram of the working principle of a piezoelectric active control system for vibration suppression in industrial robot cutting processes according to the present invention. Figure 6 This is a flowchart of the PID algorithm control theory of a piezoelectric active control system for vibration suppression in industrial robot cutting processes according to the present invention. The labels in the attached figures are as follows: 1. Robot end effector spindle; 2. Conductive slip ring; 3. Wire; 4. Cutting tool; 5. Custom tool holder; 6. Lug; 7. Stiffness enhancement module; 8. Ring piezoelectric ceramic stacked actuator pre-tightening fixing device; 9. Hemispherical hinge; 10. Spring collet; 11. Custom nut; 12. Ring piezoelectric ceramic stacked actuator protection device; 13. Ring piezoelectric ceramic stacked actuator inner ring support shaft; 14. M3 round head hex bolt; 15. M3 hex head bolt; 16. Wire hole; 17. Custom nut groove; 18. Ring piezoelectric ceramic stacked actuator pre-tightening fixing device recess; 19. Voltage amplifier; 20. DSP signal controller; 21. Dynamic test and analysis system; 22. Acceleration and displacement sensor; 23. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0031] Please see Figures 1-6 The present invention provides a technical solution: a vibration suppression system for industrial robot cutting, comprising a robot body, a cutting tool 4, a piezoelectric active vibration damping device and a piezoelectric control device; The robot body is equipped with a robot end effector at one end, and the cutting tool 4 is connected to the robot end effector through a custom tool holder 5; The piezoelectric active vibration damping device is installed and connected to the spindle of the robot end effector. The overall vibration damping device is installed and connected to the spindle of the industrial robot end effector through the M3 connecting bolt and the customized tool holder 5. When the external sensor detects the vibration signal generated by the tool, the control device performs corresponding signal processing according to the detected signal, and finally transmits the processed voltage signal to the piezoelectric active control core device. The inverse piezoelectric effect of the ring piezoelectric ceramic stacked actuator 12 converts electrical energy into mechanical energy, thereby canceling the vibration energy generated during the cutting process. The alternating voltage in the ring piezoelectric ceramic stacked actuator 12 is controlled according to the changes in external excitation under different working conditions, thereby adjusting the output of the piezoelectric ceramic stacked actuator in real time to obtain a good vibration damping effect and improve machining stability.

[0032] The piezoelectric active vibration damping device for vibration suppression in industrial robot cutting is designed in a circular shape with a smooth and flat surface and no extra protrusions. This helps to reduce the wind resistance encountered by the piezoelectric active vibration damping device in high-speed cutting. The overall design of the piezoelectric active vibration damping device is a completely symmetrical structure, which ensures the dynamic balance of the piezoelectric active vibration damping device in high-speed cutting.

[0033] The piezoelectric active vibration damping device includes a conductive slip ring 2, a wire 3, a lug 6, a stiffness enhancement module 7, a pre-tightening fixing device for a ring-shaped piezoelectric ceramic stacked actuator 8, a hemispherical hinge 9, a spring collet 10, a custom nut 11, a ring-shaped piezoelectric ceramic stacked actuator 12, a ring-shaped piezoelectric ceramic stacked actuator protection device 13, an inner ring support shaft for the ring-shaped piezoelectric ceramic stacked actuator 14, an M3 round head hexagon socket bolt 15, an M3 hexagon head bolt 16, a wire hole 17, a custom nut groove 18, and a recessed platform for the pre-tightening fixing device for the ring-shaped piezoelectric ceramic stacked actuator 19.

[0034] In industrial robot cutting processes, a piezoelectric active vibration damping device is installed and connected to a customized tool holder 5 and the robot end effector spindle 1. A stiffness enhancement module 7 is fitted around the outer ring of the customized tool holder 5. The stiffness enhancement module 7 and the customized tool holder 5 are interference-fitted to ensure a tight connection. Furthermore, the upper and lower bosses of the stiffness enhancement module 7 and the conductive slip ring 2 are clearance-fitted to ensure smooth assembly and easy disassembly during installation. The lower boss of the stiffness enhancement module 7 and the annular piezoelectric ceramic stack actuation device... The pre-tightening fixing device 8 is fixed by an M3 threaded connection. Four M3 bolt holes are evenly distributed on the lower boss of the stiffness enhancement module 7 and the circumference of the ring piezoelectric ceramic stack actuator pre-tightening fixing device 8. A recessed platform is provided in the middle of the ring piezoelectric ceramic stack actuator pre-tightening fixing device 8. On the bottom surface of the recessed platform, around the customized tool holder 5, are four symmetrically distributed inner ring support shafts 14 for the ring piezoelectric ceramic stack actuator. Each inner ring support shaft 14 is connected to the ring piezoelectric ceramic stack actuator via M3 bolts symmetrically connected on the left and right sides. The pre-tightening fixing device of the ceramic stack actuator is fixed on the bottom surface of the recessed platform 19. Each set of connecting bolts not only serves a connecting and fixing function but also allows for the application of corresponding torque using a torque wrench, thereby generating a corresponding pre-tightening force on the annular piezoelectric ceramic stack actuator 12. The annular piezoelectric ceramic stack actuator 12, the annular piezoelectric ceramic stack actuator protection device 13, and the hemispherical hinge 9 are directly bonded together. The specific model of the annular piezoelectric ceramic stack actuator 12 is NAC2124-Hxx. During the machining process, the hemispherical hinge 9 bonded to the lower end of the annular piezoelectric ceramic stacked actuator 12 directly contacts the custom nut groove 11, thereby allowing the thrust generated by the annular piezoelectric ceramic stacked actuator 12 to act directly on the custom nut 11, and the generated torque is further transmitted to the cutting tool 4; the four annular piezoelectric ceramic stacked actuators 12 are evenly distributed in a ring array at 90° intervals around the custom tool holder 5, so that they can be arbitrarily combined to cancel the cutting force in any direction on the plane, thereby playing an active vibration reduction role.

[0035] In a preferred embodiment, the custom tool holder 5, lug 6, custom nut 11, cutting tool 4, spring collet 10, and stiffness enhancement module 7 are made of 20CrMnTi; the annular piezoelectric ceramic stacked actuator pre-tightening fixing device 8, annular piezoelectric ceramic stacked actuator inner ring support shaft 14, annular piezoelectric ceramic stacked actuator protection device 13, and hemispherical hinge 9 are made of heat-treated 45# steel; the bolts are all made of stainless steel, and the wire 3 is made of copper enameled wire. The conductive slip ring 2 is a sliding contact body, and its material is mainly graphite; the annular piezoelectric ceramic stacked actuator 12 is formed by alternating stacking and bonding of single-layer piezoelectric ceramic sheet PZT-5 and metal electrode layer, with a 2mm thick unpolarized insulating ceramic sheet on the top and bottom of the stack, single-layer ceramic thickness: 0-0.5mm, electrostatic capacitance / cm³: 100nF, thermal expansion coefficient: +2ppm / ℃, and driving voltage 500V or 1000V.

[0036] Specifically, the piezoelectric control device includes an acceleration displacement sensor 23, a DSP signal controller 21, a voltage amplifier 20, and a dynamic testing and analysis system 22. The acceleration displacement sensor 23 is mounted on the end spindle of the cutting robot near the tool position via a magnet, and the X, Y, and Z directions of the acceleration displacement sensor are aligned with the base coordinates of the industrial robot. The acceleration displacement sensor 23 is connected to the dynamic testing and analysis system 22 via signal lines, and the output of the voltage amplifier 20 is connected to the ring-shaped piezoelectric ceramic stacked actuator 12. The acceleration displacement sensor 23 is used to detect the tool vibration signal during the cutting robot's machining in real time and transmits the vibration signal to the dynamic testing and analysis system 22. The dynamic testing and analysis system 22 converts the vibration signal into a frequency signal, i.e., the vibration frequency of the cutting process. The DSP signal controller 21 processes the frequency signal and finally outputs a relative frequency signal. The corresponding AC voltage is sent to the voltage amplifier 20; the voltage amplifier 20 is used to amplify the voltage signal processed by the DSP signal controller 21, so that the ring piezoelectric ceramic stacked actuator 12 can output the corresponding thrust under the voltage input of the voltage amplifier; when the acceleration displacement sensor detects the vibration signal generated by the tool detection point, the control device performs corresponding signal processing according to the detected signal, and finally transmits the processed voltage signal to the piezoelectric active control core device. Through the inverse piezoelectric effect of the ring piezoelectric ceramic stacked actuator 12, electrical energy is converted into mechanical energy, thereby canceling the vibration energy generated during the cutting process. The alternating voltage change in the ring piezoelectric ceramic stacked actuator 12 is controlled according to the change of external excitation under different working conditions, thereby adjusting the output of the piezoelectric ceramic stacked actuator in real time, obtaining a good vibration reduction effect and improving machining stability.

[0037] The dynamic test and analysis system 22 uses Donghua vibration test and analysis software to perform FFT transformation on the amplified tool vibration acceleration signal, which can obtain the real-time vibration frequency signal.

[0038] In a preferred embodiment, a control algorithm is embedded in the DSP signal controller. Piezoelectric ceramics are materials that can generate force and displacement by applying voltage. In many applications, controlling piezoelectric ceramics to achieve precise force and displacement is a very important issue. Therefore, this invention uses a PID control algorithm to control the vibration generated during the cutting process of an industrial robot. The PID control algorithm used in this invention uses the difference between the value of the required setpoint and the value measured in real time by the acceleration and displacement sensor as the error value. The required setpoint value is 0, representing the vibration displacement of the tool under ideal conditions, which is a fixed theoretical value. In addition to the error value required for the proportional term, the accumulated error value of the integral term and the error calculation value of the derivative term are also required. These calculated values ​​are continuously refreshed at different sampling times. Finally, the final value of the control variable is obtained through the basic control law of the PID control algorithm. By embedding a control algorithm in the DSP signal controller, piezoelectric ceramics, a material that can generate force and displacement by applying voltage, are crucial for controlling the precise force and displacement of piezoelectric ceramics in numerous applications. Therefore, this invention employs a PID control algorithm to control the vibration generated during the cutting process of an industrial robot. The PID control algorithm used in this invention calculates the difference between the desired setpoint value and the real-time measurement value from the acceleration and displacement sensor as the error value. The desired setpoint value of 0 represents the ideal vibration displacement of the tool, a fixed theoretical value. Besides the error value required for the proportional term, the accumulated error value for the integral term and the calculated error value for the derivative term are also needed. These calculated values ​​are continuously updated at different sampling times. Finally, the final value of the control variable is obtained through the basic control laws of the PID control algorithm. ; In the above formula This is the proportional gain, which is the tuning parameter; This is the integral gain, which is also the tuning parameter; The differential gain is also the tuning parameter. These three parameters are randomly combined and selected according to different processing application scenarios and variable conditions until the vibration reduction effect reaches the best. By selecting appropriate coefficients, an excellent PID controller can be achieved. Error = Required setpoint value r - Real-time measured value of acceleration displacement sensor; t is the current time; In this invention, an acceleration-displacement sensor measures the vibration amplitude of the cutting tool in real time, sampling it at regular intervals and transmitting the sample as feedback to a PID controller. After signal processing by a DSP signal controller and calculation by the PID control algorithm, the output control variable is determined. Finally, based on the functional relationship between voltage and displacement in the ring piezoelectric ceramic stack actuator 12, the voltage output of the voltage amplifier is adjusted, causing the ring piezoelectric ceramic stack actuator 12 to generate corresponding displacement and force to counteract the vibration of the cutting tool. The basic PID algorithm flowchart is shown in the attached specification. Figure 6 As shown. Example

[0039] Based on the vibration suppression system for industrial robot cutting proposed in Embodiment 1 above, this embodiment further discloses a vibration reduction method for the vibration suppression system for industrial robot cutting, see the appendix to the specification. Figure 4 The working process of the active vibration damping device includes: monitoring the vibration displacement / acceleration of the tool detection point during the robot cutting process through an acceleration displacement sensor; and outputting a corresponding alternating voltage signal by an external control device based on the vibration of the tool detection point, thereby changing the thrust output of the piezoelectric active vibration damping device.

[0040] A vibration reduction method for a vibration suppression system used in industrial robot cutting, the vibration reduction method specifically includes the following steps: Step S1: Detect the vibration acceleration and displacement of the tool detection point on the customized tool during the cutting process of the robot body using the acceleration and displacement sensor; Step S2: Based on the vibration of the tool detection point, the input alternating voltage of the piezoelectric active vibration damping device is controlled externally, thereby changing the thrust output of the piezoelectric active vibration damping device.

[0041] Step S1 includes: Step S101: Determine the relationship between the vibration acceleration in the X and Y directions and the vibration acceleration in the Z direction of the current tool detection point, as well as the vibration displacement in the X and Y directions and the vibration displacement in the Z direction of the tool vibration detection point. The determination results include condition A and condition B. Condition A corresponds to processing flow A'; condition B corresponds to processing flow B'. Step S102: After obtaining the judgment result as condition A or condition B, determine the relationship between the maximum thrust that the ring piezoelectric ceramic stacked actuator 12 can generate and the expected thrust. The relationship conditions include condition C and condition D; where condition C corresponds to processing flow C'; and condition D corresponds to processing flow D'.

[0042] Condition A is: when the vibration acceleration of the tool detection point in the X and Y directions during the robot cutting process is greater than or equal to the vibration acceleration in the Z direction, and the vibration displacement of the tool vibration detection point in the X and Y directions is greater than or equal to the vibration displacement in the Z direction, the processing flow A' is executed. The specific operation of process A' is as follows: Based on the vibration balance condition analysis of the cutting tool, the expected output thrust of a set of annular piezoelectric ceramic stacked actuators 12 in the X or Y direction is calculated by the following formula: ; in The distance between the center of the custom nut 11 and the center of the end of the tool; The distance between the center of the custom nut 11 and the point of action of the annular piezoelectric ceramic stacked actuator 12; The radial cutting force acting on the tool at this moment is obtained by processing the acceleration in the X or Y direction; Determine the relationship between the maximum thrust that the annular piezoelectric ceramic stacked actuator 12 can generate and the desired thrust. The relationship conditions include condition C, which corresponds to processing flow C'; and condition D, which corresponds to processing flow D'.

[0043] Condition B: When the vibration acceleration in the X and Y directions of the tool detection point during robot cutting is less than the vibration acceleration in the Z direction, and the vibration displacement in the X and Y directions of the tool vibration detection point is less than the vibration displacement in the Z direction, process flow B' is executed. Based on the balance condition analysis of the cutting tool, the expected output thrust of the four annular piezoelectric ceramic stacked actuators 12 is calculated by the following formula: ; In the formula For the desired thrust, The applied voltage amplitude, The equivalent mechanical stiffness of the toroidal piezoelectric ceramic stacked actuator 12 is given. The equivalent electrical stiffness of the ring piezoelectric ceramic stacked actuator 12; Determine the relationship between the maximum thrust range that the annular piezoelectric ceramic stacked actuator 12 can generate and the desired thrust. The relationship conditions include condition C, corresponding to processing flow C'; and condition D, corresponding to processing flow D'.

[0044] The condition C is: during robot cutting, the expected thrust of the annular piezoelectric ceramic stacked actuator 12 is within the output thrust range. The output thrust range is determined by the selected model of the actual annular piezoelectric ceramic stacked actuator 12, and its maximum value can reach about 5700N. Then, the processing flow C' is executed. The process C' is as follows: Adjust the alternating voltage input of the piezoelectric controller to the annular piezoelectric ceramic stack actuator 12 so that the output thrust of the annular piezoelectric ceramic stack actuator 12 is equal to the desired thrust.

[0045] The condition D is: when the desired thrust of the vibration damping device is outside the above-mentioned output thrust range during robot cutting, the processing flow D' is executed. The process D' is as follows: Adjust the model of the annular piezoelectric ceramic stacked actuator 12 in the piezoelectric active vibration damping device, and select an annular piezoelectric ceramic stacked actuator 12 model whose output thrust can reach the desired thrust under ideal conditions, until the tool vibration is reduced and meets the requirements.

[0046] The piezoelectric ceramic used in this application is a smart material with a piezoelectric effect. When an external force or electric field is applied, charge separation occurs, causing it to exhibit mechanical motion or mechanical strain characteristics. Therefore, the active vibration reduction method based on piezoelectric ceramic materials can suppress different types of processing vibrations by changing the alternating voltage of the external power supply. Compared with traditional passive and semi-active vibration reduction, it has the following advantages: 1) Adaptability: Active vibration reduction can sense the vibration state of the structure in real time and make real-time adjustments as needed. It can automatically adapt to different vibration conditions and frequencies, ensuring that it always maintains a good vibration reduction effect. 2) High efficiency: Active vibration reduction can reduce the vibration amplitude and frequency by adjusting system parameters or applying control forces. It can achieve a greater degree of vibration suppression in a shorter time and provide a more efficient vibration reduction effect. 3) Multifunctionality: Active vibration reduction methods can use a variety of technical means, such as active mass adjustment, electromagnetic force excitation, and piezoelectric material control. These methods can provide more vibration control functions, such as adjusting the mass distribution of the structure, changing the stiffness and damping characteristics of the structure, etc. 4) Precision: Active vibration damping monitors vibration in real time through sensors, and, in conjunction with a precise control system and actuators, enables precise control of structural vibration. It can achieve accurate vibration suppression across different frequencies and amplitudes, providing a more precise vibration reduction effect.

[0047] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A vibration suppression system for industrial robot cutting, characterized in that: Includes the robot body, cutting tool (4), piezoelectric active vibration damping device and piezoelectric control device; The robot body is equipped with a robot end effector at one end, and the cutting tool (4) is connected to the robot end effector through a custom tool holder (5); The piezoelectric active vibration damping device is installed and connected to the main shaft (1) of the robot end effector; The piezoelectric active vibration damping device includes a stiffness enhancement module (7), a conductive slip ring (2), and an annular piezoelectric ceramic stacked actuator (12). The stiffness enhancement module (7) is sleeved on the outside of the custom tool holder (5), the conductive slip ring (2) is sleeved on the outside of the stiffness enhancement module (7), and the annular piezoelectric ceramic stacked actuator (12) is distributed around the custom tool holder (5). The annular piezoelectric ceramic stacked actuator (12) is connected to the inner ring of the conductive slip ring (2), and the outer ring of the conductive slip ring (2) is connected to the piezoelectric control device. The alternating voltage output of the piezoelectric control device is adjusted according to the vibration under different working conditions and external excitation, thereby controlling the alternating voltage of the inner electrode of the annular piezoelectric ceramic stacked actuator (12), changing the thrust and displacement generated therefrom, so as to counteract the vibration generated by the tool during the machining process. The annular piezoelectric ceramic stacked actuators (12) are arranged in an equidistant annular array, and the annular piezoelectric ceramic stacked actuators (12) are distributed on the outside of the custom tool holder (5). The lower end of the annular piezoelectric ceramic stacked actuators (12) is provided with a semi-spherical hinge (9). The semi-spherical hinge (9) and the groove of the custom nut (11) fit together. The annular piezoelectric sheet inside the annular piezoelectric ceramic stacked actuators (12) is made of piezoelectric ceramic. The upper surface of the upper boss of the stiffness enhancement module (7) and the upper surface of the conductive slip ring (2) are on the same plane, and the stiffness enhancement module (7) and the custom tool holder (5) are interference fit; The piezoelectric active vibration damping device also includes a ring piezoelectric ceramic stacked actuator pre-tightening fixing device (8). The upper end face of the ring piezoelectric ceramic stacked actuator pre-tightening fixing device (8) is attached to the stiffness enhancement module (7). On the concave bottom surface of the ring piezoelectric ceramic stacked actuator pre-tightening fixing device (8), there are several equally spaced ring-shaped inner ring support shafts (14) of the ring piezoelectric ceramic stacked actuator around the customized tool holder (5). The ring piezoelectric ceramic stacked actuator (12) pre-tightening sleeve in the ring piezoelectric ceramic stacked actuator pre-tightening fixing device (8) is bonded together with the ring piezoelectric ceramic stacked actuator (12).

2. The vibration suppression system for industrial robot cutting according to claim 1, characterized in that: The piezoelectric control device includes an acceleration displacement sensor (23), a DSP signal controller (21), a voltage amplifier (20), and a dynamic test and analysis system (22). The acceleration displacement sensor is connected to the dynamic test and analysis system via a signal line, and the output of the voltage amplifier is connected to the ring piezoelectric ceramic stacked actuator. The acceleration displacement sensor is mounted on the spindle of the robot end effector near the cutting tool via a magnet mount, and the X, Y, and Z directions of the acceleration displacement sensor are aligned with the base coordinates of the robot body. The acceleration displacement sensor is used to detect the vibration signal of the cutting tool during machining in real time and transmits the vibration signal to the dynamic test and analysis system. The dynamic test and analysis system converts the vibration signal into a frequency signal, i.e., the vibration frequency of the cutting process. The DSP signal controller processes the frequency signal and finally outputs a corresponding AC voltage to the voltage amplifier. The voltage amplifier amplifies the voltage signal output by the DSP signal controller after processing, enabling the ring piezoelectric ceramic stacked actuator to output a corresponding thrust under the voltage input to the voltage amplifier.

3. A vibration reduction method for a vibration suppression system used in industrial robot cutting according to any one of claims 1-2, characterized in that: The vibration reduction method specifically includes the following steps: Step S1: Detect the vibration acceleration and displacement of the tool detection point on the cutting tool during the cutting process of the robot body using the acceleration and displacement sensor; Step S2: Based on the vibration of the tool detection point, the input alternating voltage of the piezoelectric active vibration damping device is controlled externally, thereby changing the thrust output of the piezoelectric active vibration damping device.

4. The vibration reduction method for a vibration suppression system used in industrial robot cutting according to claim 3, characterized in that: Step S1 includes: Step S101: Determine the relationship between the vibration acceleration in the X and Y directions and the vibration acceleration in the Z direction of the current tool detection point, as well as the vibration displacement in the X and Y directions and the vibration displacement in the Z direction of the tool vibration detection point. The determination results include condition A and condition B. Condition A corresponds to processing flow A'; condition B corresponds to processing flow B'. Step S102: After obtaining the judgment result as either condition A or condition B, determine the relationship between the maximum thrust that the ring piezoelectric ceramic stacked actuator can generate and the expected thrust. The relationship conditions include condition C and condition D; where condition C corresponds to processing flow C' and condition D corresponds to processing flow D'.

5. A vibration reduction method for a vibration suppression system used in industrial robot cutting according to claim 4, characterized in that: Condition A is: when the vibration acceleration of the tool detection point in the X and Y directions during the robot cutting process is greater than or equal to the vibration acceleration in the Z direction, and the vibration displacement of the tool vibration detection point in the X and Y directions is greater than or equal to the vibration displacement in the Z direction, the processing flow A' is executed. The specific operation of process A' is as follows: Based on the vibration balance condition analysis of the cutting tool, the expected output thrust of a set of annular piezoelectric ceramic stacked actuators in the X or Y direction is calculated by the following formula: ； in The distance between the center of the customized nut and the center of the tool tip; The distance between the center of the custom nut and the point of action of the annular piezoelectric ceramic stack actuator; The radial cutting force acting on the tool at this moment is obtained by processing the acceleration in the X or Y direction; Determine the relationship between the maximum thrust that the toroidal piezoelectric ceramic stack actuator can generate and the desired thrust. The relationship conditions include condition C, corresponding to processing flow C'; and condition D, corresponding to processing flow D'.

6. The vibration suppression system and vibration reduction method for industrial robot cutting according to claim 4, characterized in that: Condition B: When the vibration acceleration in the X and Y directions of the tool detection point during robot cutting is less than the vibration acceleration in the Z direction, and the vibration displacement in the X and Y directions of the tool vibration detection point is less than the vibration displacement in the Z direction, process flow B' is executed. Based on the balance condition analysis of the cutting tool, the expected output thrust of the four annular piezoelectric ceramic stack actuators is calculated by the following formula: ； In the formula For the desired thrust, The applied voltage amplitude, This represents the equivalent mechanical stiffness of the toroidal piezoelectric ceramic stack actuator. The equivalent electrical stiffness of the toroidal piezoelectric ceramic stacked actuator; Determine the relationship between the maximum thrust range that the toroidal piezoelectric ceramic stack actuator can generate and the desired thrust. The relationship conditions include condition C, corresponding to processing flow C'; and condition D, corresponding to processing flow D'.

7. The vibration suppression system and vibration reduction method for industrial robot cutting according to claim 4, characterized in that: The condition C is: during robot cutting, the expected thrust of the ring piezoelectric ceramic stacked actuator is within the output thrust range. The output thrust range is determined by the selected model of the actual ring piezoelectric ceramic stacked actuator, and its maximum value can reach 5700N. Then, process flow C' is executed. The process C' is as follows: Adjust the alternating voltage input of the piezoelectric controller to the ring piezoelectric ceramic stack actuator so that the output thrust of the ring piezoelectric ceramic stack actuator is equal to the desired thrust.

8. A vibration suppression system and vibration reduction method for industrial robot cutting according to claim 7, characterized in that: The condition D is: when the desired thrust of the vibration damping device is outside the above-mentioned output thrust range during robot cutting, the processing flow D' is executed. The process D' is as follows: Adjust the model of the annular piezoelectric ceramic stack actuator in the piezoelectric active vibration damping device, and select an annular piezoelectric ceramic stack actuator model that can output the desired thrust under ideal conditions, until the tool vibration is reduced and meets the requirements.

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