Elliptical cutting rapid tool servo device and motion control method thereof

Abstract

The application belongs to the technical field of computer and provides an elliptical cutting quick tool servo device and a motion control method thereof.The device comprises a tool fixing seat, a hinge, a control surface, a piezoelectric driver, a displacement sensor, a diamond tool, an inclined pull rod and a three-axis frame, wherein the tool fixing seat is connected with the control surface through the hinge, the piezoelectric driver is arranged on the other side of the control surface away from the tool fixing seat, one end of the piezoelectric driver is connected with the control surface through the hinge, the other end is connected with the three-axis frame, the displacement sensor is arranged between the control surface and the tool fixing seat, the diamond tool is arranged at the first diagonal position of the tool fixing seat, one end of the inclined pull rod is connected with the second diagonal position of the tool fixing seat through the hinge, and the other end is connected with the three-axis frame.The application realizes independent adjustment of the position and posture of the diamond tool under multiple degrees of freedom and improves the position and posture control precision during diamond tool machining.

Description

Technical Field

[0001] This invention belongs to the field of workpiece machining technology, and particularly relates to a servo device for elliptical cutting rapid tooling and its motion control method. Background Technology

[0002] Freeform surface fabrication technology is of great significance for the manufacturing of high-precision optical components. With the development of science and technology, freeform surface optical components have been gradually applied in important technical fields such as aerospace, defense, military, and medicine. Among them, the use of Fast Tool Servo (FTS) technology to achieve three-dimensional ellipse machining is considered a highly promising micro-nano fabrication technology.

[0003] Currently, FTS (Flexible Switching) has evolved from single-degree-of-freedom (SDOF) to multi-degree-of-freedom (FPS). Single-degree-of-freedom FTS machining has limitations: it can only perform reciprocating motion in one direction and correct errors along a single axis of motion, and it can only satisfy constant feed toolpaths, rendering it ineffective for complex curved surfaces. Therefore, based on single-degree-of-freedom FTS, multi-degree-of-freedom FTS has been proposed for rapid servo machining of complex curved surfaces. Multi-degree-of-freedom FTS can achieve multi-directional active cutting and multi-directional displacement compensation, solve cutting force disturbances, and achieve synchronization and coordination between the machine tool spindle and the FTS device. It overcomes the problems existing in single-degree-of-freedom FTS machining and expands the field and capabilities of FTS diamond turning based on NRS (Non-Resistant Rotation System) surface machining. Therefore, the research on multi-degree-of-freedom FTS devices is of great significance.

[0004] The classic structure of existing FTS machining devices mainly employs an FTS mechanism where an FTS device is mounted on the X-axis guideway of an ultra-precision CNC lathe, with the diamond tool clamped on it and the workpiece mounted on the spindle or shaft of the ultra-precision lathe. The diamond tool can be driven by the FTS to achieve rapid reciprocating motion along the spindle direction, and can also perform X and Z-axis feed motions along the guideway. During machining, the tool performs two-way feed motions along the X and Z guideways, and is also driven by the FTS to perform rapid reciprocating motion along the spindle. Both operate simultaneously, with the FTS compensating for guideway displacement errors, achieving macro-micro composite machining and improving the machining accuracy of the diamond tool. However, due to the characteristic of dedicated machine tools, a single machine tool can only process the same type of parts, resulting in poor versatility of FTS machining devices, leading to high machining costs and low production efficiency. Furthermore, existing FTS machining devices typically only support limited degrees of freedom motion adjustment, such as linear displacement or rotation in a single direction, making it difficult to achieve multi-degree-of-freedom diamond tool pose error compensation, and thus failing to meet the precise adjustment requirements for workpiece posture during complex surface machining. Furthermore, existing FTS machining equipment focuses on enhancing stiffness in the machining direction to meet the cutting force requirements in that direction, while neglecting the stiffness in non-machining directions. This makes it difficult to guarantee absolute stiffness in other directions, and the workpiece is prone to slight displacement or deformation in non-machining directions, thus affecting machining accuracy and surface quality. In addition, diamond tools have a small operating space, making it difficult to handle the machining of complex shapes and highly deformable curved surfaces. Summary of the Invention

[0005] The purpose of this invention is to provide a fast servo device for elliptical cutting tools and its motion control method, which aims to solve the problem that the insufficient degree of freedom of tool pose control in the prior art makes it difficult to meet the requirements of high-precision complex surface machining.

[0006] In a first aspect, the present invention provides a fast tool servo device for elliptical cutting, comprising: a tool holder, a hinge, a control surface, a piezoelectric actuator, a displacement sensor, a diamond tool, a tie rod, and a triaxial frame.

[0007] The tool holder is connected to the control surface via the hinge. The piezoelectric actuator is located on the control surface opposite to the tool holder, with one end connected to the control surface via the hinge and the other end connected to the triaxial frame. The displacement sensor is located between the control surface and the tool holder to measure the relative displacement between the control surface and the surface of the tool holder. The diamond tool is located at the first diagonal position of the tool holder. One end of the diagonal tie rod is connected to the second diagonal position of the tool holder via the hinge, and the other end is connected to the triaxial frame.

[0008] In some embodiments, the hinge includes a driving hinge, a coupling hinge, and a flexible hinge. The driving hinge connects the control surface to the piezoelectric actuator, the coupling hinge connects the control surface to the tool holder, and the flexible hinge connects the tie rod to the tool holder.

[0009] In some embodiments, the tool holder includes three orthogonally distributed mounting surfaces, each of which is connected to the corresponding control surface via four square-distributed coupling hinges.

[0010] In some embodiments, each of the control surfaces, located away from the tool holder, is connected to a set of piezoelectric actuators via three drive hinges arranged in an equilateral triangle.

[0011] In some embodiments, the set of piezoelectric actuators includes three piezoelectric actuators arranged in an equilateral triangle.

[0012] In some embodiments, the first diagonal position and the second diagonal position are spatially diagonally distributed;

[0013] Three displacement sensors are disposed between each of the control surfaces and each of the mounting surfaces, and the three displacement sensors are arranged in an equilateral triangle.

[0014] Secondly, the present invention provides a motion control method for an elliptical cutting rapid tool servo device as described above, comprising the following steps:

[0015] Based on the current pose parameters and target pose parameters of the diamond tool, the static control quantity of each piezoelectric actuator is calculated respectively.

[0016] The piezoelectric actuator is driven to work according to the calculated static control quantity, so that the piezoelectric actuator adjusts the diamond tool in the current pose to the target pose.

[0017] The dynamic control quantity of the piezoelectric actuator is generated according to the preset motion trajectory parameters;

[0018] The diamond tool located at the target pose is dynamically driven and controlled according to the generated dynamic control quantity, so that the diamond tool performs an elliptical cutting motion with a spiral advance.

[0019] When the diamond tool completes its cutting cycle or reaches the reset position, it is moved to the zero position via the hinge under the action of the tie rod.

[0020] In some embodiments, the step of calculating the static control quantity of each piezoelectric actuator based on the current pose parameters and target pose parameters of the diamond tool includes:

[0021] The position and pose parameters of the control surface are obtained through the displacement sensor, and the position and pose parameters of the diamond tool are determined based on the obtained position and pose parameters according to the coupling mapping relationship between the control surface and the diamond tool.

[0022] Based on the target position parameters and current position parameters of the diamond tool, the position adjustment amount of each group of piezoelectric actuators is calculated through the coupling mapping relationship;

[0023] Based on the target attitude parameters and current attitude parameters of the diamond tool, the attitude adjustment amount of each group of piezoelectric actuators is calculated using a nonlinear attitude decoupling algorithm.

[0024] The position adjustment amount and the attitude adjustment amount are superimposed to generate the static control amount for each piezoelectric actuator.

[0025] In some embodiments, the step of dynamically driving the diamond tool located at the target pose according to the generated dynamic control quantity includes:

[0026] The Z-axis is set as the feed axis, and the group of piezoelectric actuators to which the Z-axis is located is controlled to maintain synchronous elongation motion according to the dynamic control component on the Z-axis to perform linear feed;

[0027] The X-axis and Y-axis are set as elliptical motion axes, and the two sets of piezoelectric actuators on the X-axis and Y-axis are controlled to synchronously perform periodic elliptical trajectory motion with sine and cosine coupling according to the dynamic control components on the X and Y axes.

[0028] In some embodiments, the coupling mapping relationship between the control surface and the diamond tool is constructed based on the relative displacement between the control surface and the tool holder measured by the displacement sensor.

[0029] This invention provides a rapid servo device for elliptical cutting tools. The device includes a tool holder, a hinge, a control surface, a piezoelectric actuator, a displacement sensor, a diamond tool, a tie rod, and a three-axis frame. By coordinating the tool holder, the control surface, and the piezoelectric actuator, combined with the hinge coupling structure, the position and attitude adjustment of the diamond tool are decoupled, enabling independent adjustment of the diamond tool's position and attitude under multiple degrees of freedom, thereby improving the position and attitude control accuracy during diamond tool machining. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the elliptical cutting rapid tool servo device provided in an embodiment of the present invention;

[0031] Figure 2This is another schematic diagram of the elliptical cutting rapid tool servo device provided in an embodiment of the present invention;

[0032] Figure 3 This is a partial schematic diagram of the elliptical cutting rapid tool servo device provided in an embodiment of the present invention;

[0033] Figure 4 This is another partial schematic diagram of the elliptical cutting rapid tool servo device provided in an embodiment of the present invention;

[0034] Figure 5 This is a schematic flowchart of the motion control method for the elliptical cutting rapid tool servo device provided in an embodiment of the present invention;

[0035] Figure 6 This is a schematic diagram of an elliptical cutting trajectory in a three-dimensional rectangular coordinate system provided in an embodiment of the present invention;

[0036] Figure 7 This is a flowchart illustrating step S100 provided in an embodiment of the present invention;

[0037] Figure 8 This is a schematic diagram of the spatial layout of the piezoelectric actuator-first control surface provided in an embodiment of the present invention;

[0038] Figure 9 This is a schematic diagram of the tool fixing seat posture change provided in an embodiment of the present invention;

[0039] Figure 10 This is a flowchart illustrating step S400 provided in an embodiment of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0041] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described feature, integral, step, operation, element, and / or component, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. Furthermore, the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise. The terms "first," "second," and similar words do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Words such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Above," "below," "left," "right," etc., are used only to indicate relative positional relationships, which may change accordingly when the absolute position of the described object changes.

[0042] To keep the following description of the embodiments of the present invention clear and concise, detailed descriptions of some known functions and known components are omitted in this specification.

[0043] This invention provides a fast tool servo device 1 for elliptical cutting, please refer to the following: Figures 1 to 5 As shown in the figure, the elliptical cutting rapid tool servo device 1 includes: a tool holder 10, a hinge 20, a control surface 30, a piezoelectric actuator 40, a displacement sensor (not shown), a diamond tool 60, a tie rod 70, and a three-axis frame 80. The tool holder 10 is connected to the control surface 30 via the hinge 20. The piezoelectric actuator 40 is located on the side of the control surface 30 opposite to the tool holder 10, with one end of the piezoelectric actuator 40 connected to the control surface 30 via the hinge 20 and the other end connected to the three-axis frame 80. The displacement sensor is located between the control surface 30 and the tool holder 10 and is used to measure the relative displacement between the control surface 30 and the surface of the tool holder 10. The diamond tool 60 is located at the first diagonal position of the tool holder 10. One end of the tie rod 70 is connected to the second diagonal position of the tool holder 10 via the hinge 20, and the other end is connected to the three-axis frame 80. In this embodiment of the invention, the tool holder 10, control surface 30 and piezoelectric actuator 40 work together in conjunction with the hinge 20 coupling structure to decouple the position and attitude adjustment of the diamond tool 60, thereby achieving independent adjustment of position and attitude under multiple degrees of freedom, thus improving the position and attitude control accuracy of the diamond tool 60 during machining.

[0044] In some embodiments, the tool holder 10 has a generally cubic block structure, including three orthogonally distributed mounting surfaces: a first mounting surface 11, a second mounting surface 12, and a third mounting surface 13. Each mounting surface is connected to its corresponding control surface 30. The first mounting surface 11, the second mounting surface 12, and the third mounting surface 13 are mutually perpendicular, forming an orthogonal spatial structure to ensure that motion components applied by each control surface, such as motion or force in the X, Y, and Z axes, can be independently transmitted to the tool holder 10, thereby achieving precise positioning and attitude control of the diamond tool 60 in three-dimensional space.

[0045] In some embodiments, the hinge 20 includes a drive hinge 21, a coupling hinge 22, and a flexible hinge 23. The drive hinge 21 is used to connect the control surface 30 and the piezoelectric actuator 40, the coupling hinge 22 is used to connect the control surface 30 and the tool holder 10, and the flexible hinge 23 is used to connect the tie rod 70 and the tool holder 10.

[0046] In some embodiments, the drive hinge 21 is configured as a one-dimensional hinge structure, in which the motion freedom of the drive hinge 21 is restricted to a single direction, for selectively absorbing and transmitting the displacement or force output generated by the piezoelectric actuator 40 in a preset direction. The drive hinge 21 amplifies and couples the displacement or force output generated by the piezoelectric actuator 40, thereby converting it into the directional motion of the control surface 30, thereby realizing the precise adjustment of the position and attitude of the control surface 30, ensuring that the control surface 30 can move flexibly and accurately within a preset trajectory and angle range.

[0047] In some embodiments, the coupling hinge 22 is configured as a two-dimensional hinge structure, in which the motion degrees of freedom of the coupling hinge 22 are restricted to orthogonally distributed biaxial directions for selectively absorbing composite displacements in the plane. The coupling hinge 22 integrates a multi-axis motion coupling unit, which can couple the motion components in the three orthogonal directions of the X, Y, and Z axes, and precisely apply the coupled motion to the tool holder 10, thereby achieving position and attitude control of the diamond tool 60 in three-dimensional space. This enables it to perform efficient and precise machining operations in complex machining environments according to preset machining paths and attitude requirements.

[0048] In some embodiments, the flexible hinge 23 may be made of an elastic material. The flexible hinge 23 has elastic deformation characteristics, which can absorb mechanical vibrations while ensuring structural rigidity and providing the necessary degrees of freedom of movement. The flexible hinge 23 utilizes the characteristics of elastic deformation to achieve backlash-free and frictionless motion transmission, providing a flexible and stable connection between the tie rod 70 and the tool holder 10, ensuring effective transmission of force and motion during system operation, while reducing motion errors caused by mechanical friction and backlash.

[0049] In some embodiments, the control surface 30 includes a first control surface 31, a second control surface 32, and a third control surface 33 that are orthogonally distributed. This unique orthogonal distribution design enables independent control of the X, Y, and Z axis movements, providing a foundation for the precise movement of the tool holder 10 in three-dimensional space. Each control surface 30 is connected to its corresponding mounting surface via four square-distributed coupling hinges 22. Specifically, the first control surface 31 is connected to the first mounting surface 11 via four square-distributed coupling hinges 22, the second control surface 32 is connected to the second mounting surface 12 via four square-distributed coupling hinges 22, and the third control surface 33 is connected to the third mounting surface 13 via four square-distributed coupling hinges 22. This ensures that the movement of the tool holder 10 in all directions is more uniform and stable, enabling the tool holder 10 to achieve precise motion control in complex machining environments. Furthermore, each control surface 30, on the side opposite to the tool holder 10, is connected to a set of piezoelectric actuators 40 via three equilateral triangular-distributed drive hinges 21. The first control surface 31, the second control surface 32, and the third control surface 33 are respectively connected to the corresponding piezoelectric actuator 40 through the drive hinge 21 group arranged in the equilateral triangle, realizing the balanced transmission of driving force and ensuring that each control surface 30 produces precise displacement and attitude adjustment under the action of the piezoelectric actuator 40.

[0050] In some embodiments, the piezoelectric actuator 40 is a non-resonant piezoelectric actuator, which has wideband response characteristics and precise displacement output capability. Each group of piezoelectric actuators consists of three independent piezoelectric actuators 40 arranged in an equilateral triangle. One end of each of the three groups of piezoelectric actuators is connected to the first control surface 31, the second control surface 32, and the third control surface 33 respectively through three drive hinges 21 arranged in an equilateral triangle, forming a one-to-one correspondence. When the piezoelectric actuator 40 receives the drive control command issued by the data processing unit (not shown) of the elliptical cutting rapid tool servo device, it generates micro-displacement and driving force based on the inverse piezoelectric effect, and accurately transmits the micro-displacement and driving force to the corresponding control surface 30 through the drive hinge 21. Thus, based on the spatial force system coupling characteristics of the triangular layout, independent drive and compound motion control of the control surface 30 in the three orthogonal directions of X, Y, and Z are realized. Specifically, the drive control command is generated by the data processing unit based on the current pose and motion state data of the control surface 30 monitored in real time by the displacement sensor. The other end of the three piezoelectric actuators is connected to the triaxial frame 80, optionally by a rigid connection with screw fasteners or by a threaded connection structure with adjustable preload, to ensure efficient transmission of driving force and structural stability.

[0051] In some embodiments, reference Figure 3The piezoelectric actuator 40 includes a first piezoelectric actuator a1, a second piezoelectric actuator a2, a third piezoelectric actuator a3, a fourth piezoelectric actuator b1, a fifth piezoelectric actuator b2, a sixth piezoelectric actuator b3, a seventh piezoelectric actuator c1, an eighth piezoelectric actuator c2, and a ninth piezoelectric actuator c3.

[0052] In some embodiments, the displacement sensors (not shown) employ non-contact, high-precision displacement measuring elements, such as capacitive or grating sensors, arranged in an array in the measurement gap between each control surface 30 and the corresponding mounting surface, for real-time measurement of the position and orientation parameters of the control surface 30 and the tool holder 10. Specifically, three displacement sensors arranged in an equilateral triangle are provided at the interface between the first control surface 31 and the first mounting surface 11, three displacement sensors arranged in an equilateral triangle are provided at the interface between the second control surface 32 and the second mounting surface 12, and three displacement sensors arranged in an equilateral triangle are provided at the interface between the third control surface 33 and the third mounting surface 13. This symmetrical and uniform distribution provides precise displacement monitoring for the precise motion control of the elliptical cutting rapid tool servo device 1 in three-dimensional space, enabling the elliptical cutting rapid tool servo device of the present invention to acquire the motion state information of the tool holder 10 in various directions in real time, thereby realizing the adjustment of the position and orientation of the tool holder 10.

[0053] In some embodiments, the diamond tool 60 is rhomboid in shape, with its center of symmetry fixed at a first diagonal position of the tool holder 10 via a precision positioning mechanism. Driven by the control surface 30, the diamond tool 60 can generate a precise elliptical cutting trajectory and effectively disperse cutting forces during the cutting process, reducing tool wear and improving cutting stability. Simultaneously, the rhomboid structure design of the diamond tool 60 helps optimize the distribution of the cutting edge, thereby significantly improving material removal rate, surface quality, and cutting efficiency in micromachining processes, and effectively reducing vibration interference during machining.

[0054] In some embodiments, the tie rod 70 is a high-strength rod-shaped structure, preferably with a circular or rectangular cross-section, made of high-strength alloy steel or titanium alloy, and its surface is hardened to enhance wear resistance and fatigue resistance. One end of the tie rod 70 is elastically connected to the tool holder via a flexible hinge 23 and is connected to the second diagonal position of the tool holder 10. The second diagonal position is the geometric center point where the first mounting surface 11, the second mounting surface 12, and the third mounting surface 13 intersect. The second diagonal position is spatially symmetrical with the first diagonal position where the diamond tool 60 is located. The other end is firmly connected to the triaxial frame 80, forming a stable mechanical support structure. The tie rod 70 is used to accelerate the return of the diamond tool 60 to the zero position, improve rapid positioning performance, and the elastic connection between the tie rod 70 and the flexible hinge 23 effectively increases the rebound stiffness, thereby enhancing the dynamic stability of the tool holder 10 during high-speed cutting and reducing positional offset and vibration interference. In addition, the rigid support of the diagonal tie rod 70 can enhance the stability of the entire device 1 during high-speed cutting or complex motion, ensuring the smooth progress of the machining process.

[0055] In some embodiments, the triaxial frame 80 adopts an orthogonal triaxial symmetrical structure, consisting of three mutually perpendicular and precision-machined high-strength alloy panels. These three panels form a stable three-dimensional orthogonal structure, providing robust support and precise spatial positioning for the device 1. Each panel has locating pin holes and threaded holes that precisely match the mounting holes of the piezoelectric actuator 40. The piezoelectric actuator 40 is rigidly fixed to the frame panel through a combination of locating pins and high-strength bolts. The three panels are fixedly connected to the other end of the diagonal tie rod 70 at the center point of their orthogonal spatial intersection via a connection interface. This orthogonal center point corresponds to the second diagonal position of the tool holder 10, thus forming a stable three-dimensional mechanical support system. This ensures efficient transmission of the driving force generated by the piezoelectric actuator 40, while providing a precise positioning reference and a stable support foundation for the diagonal tie rod 70.

[0056] This invention, through the coordinated operation of the tool holder 10, control surface 30, and piezoelectric actuator 40, combined with the coupling structure of hinge 20, decouples the position and attitude adjustment of the diamond tool 60, achieving independent adjustment of position and attitude under multiple degrees of freedom, thereby improving the position and attitude control accuracy during diamond tool machining. This invention also utilizes the design of the diagonal tie rod 70 connected to the tool holder 10 to accelerate the tool coordinate return to zero, enhance the stiffness in the non-driving direction, effectively suppress tool deviation, and improve the stability and reliability of the machining process. Furthermore, this invention expands the operating space of the diamond tool 60 through a unique three-dimensional spatial layout design, enabling it to adapt to the machining needs of complex shapes and highly deformable curved surfaces. This allows for more flexible cutting paths in three-dimensional space, enriching the toolpath planning methods for three-dimensional surface micro / nano machining, and ultimately improving the machining efficiency and surface quality of the diamond tool 60.

[0057] like Figure 5 As shown, this embodiment of the invention also provides a motion control method for the aforementioned elliptical cutting rapid tool servo device, comprising the following steps:

[0058] S100: Calculate the static control quantity of each piezoelectric actuator 40 based on the current pose parameters and target pose parameters of the diamond tool 60.

[0059] In this embodiment of the invention, the current pose parameters of the diamond tool 60 include current position parameters and current attitude parameters, and the target pose parameters include target position parameters and target state parameters. The target position parameters are preset by the user, for example, through an input device connected to the elliptical cutting rapid tool servo device via wired or wireless connection. Specifically, the displacement sensor collects the current pose parameters of the diamond tool 60 in real time and feeds this data back to the data processing unit. The data processing unit compares and analyzes the current pose parameters with the preset target pose parameters and calculates the pose error of each degree of freedom. Based on the pose error data, the data processing unit then calculates the static control quantity required by the piezoelectric actuator 40.

[0060] S200: Drive the piezoelectric actuator 40 to work according to the calculated static control quantity, so that the piezoelectric actuator adjusts the diamond tool in the current pose to the target pose.

[0061] In this embodiment of the invention, the piezoelectric actuator 40 is driven to work according to the calculated static control quantity. The piezoelectric actuator 40 transmits the driving force to the control surface 30 through the drive hinge 21, causing the control surface 30 to undergo a pose change. The control surface 30 then drives the tool holder 10 to undergo a pose change through the coupling hinge 22, thereby smoothly and accurately adjusting the diamond tool 60 from the current pose to the target pose.

[0062] S300: Generates dynamic control quantities for the piezoelectric actuator based on preset motion trajectory parameters.

[0063] In this embodiment of the invention, the preset motion trajectory parameters include dynamic characteristic parameters of the diamond tool during its movement, such as elliptical trajectory parameters and feed axis parameters. The elliptical trajectory parameters include the major axis amplitude, minor axis amplitude, elliptical frequency, and phase difference; the feed axis parameters include the feed speed and initial position. Based on the preset motion trajectory parameters and through the coupling mapping relationship between the piezoelectric actuator and the diamond tool, the dynamic control components of each piezoelectric actuator group in the first, second, and third control surfaces are calculated respectively, ultimately generating the dynamic control quantity of the piezoelectric actuator.

[0064] S400: Dynamically drive and control the diamond tool located at the target pose based on the generated dynamic control quantity, so that the diamond tool performs an elliptical cutting motion with spiral advance.

[0065] In this embodiment of the invention, three sets of piezoelectric actuators are moved according to the generated dynamic control quantity to dynamically drive the diamond tool located at the target pose. Specifically, as shown... Figure 6 As shown, one set of piezoelectric actuators is controlled to perform feed motion, while the other two sets of piezoelectric actuators are controlled to perform sinusoidal and cosine coupled motions synchronously, respectively. The three sets of piezoelectric actuators transmit the driving force generated by the motion to the control surface through drive hinges. The control surface transmits the driving force to the tool holder through coupling hinges, thereby driving the diamond tool on the tool holder to perform a spiral elliptical cutting motion in three-dimensional space, forming a smooth and continuous elliptical trajectory in the XY plane. This ensures the uniformity of material removal and surface quality of the diamond tool during elliptical cutting.

[0066] S500: When the diamond tool 60 completes the cutting cycle or reaches the reset position, the diamond tool 60 is moved to the zero position by the hinge 20 under the action of the tie rod 70.

[0067] In this embodiment of the invention, a reset mechanism is triggered when the diamond tool 60 completes a preset cutting cycle or reaches a set reset position during the machining process. This reset process achieves precise zero-positioning of the tool through the coordinated action of the tie rod 70 and the flexible hinge 23. Specifically, during the diamond tool cutting process, the flexible hinge 23 undergoes adaptive elastic deformation due to the feed action of the diamond tool. When the diamond tool 60 completes a preset cutting cycle or reaches a set reset position during the machining process, the reset mechanism is triggered. At this time, the flexible hinge 23 enters a springback phase. When the flexible hinge 23 attempts to return to its initial shape under the action of elastic deformation, this deformation is converted into an axial pulling force on the tie rod 70. The flexible hinge 23 first applies a traction force along its axis to the tie rod 70, causing the tie rod 70 to produce axial displacement. Subsequently, the tie rod 70 transmits the traction force to the connected flexible hinge 23, which in turn pulls the tool holder, ultimately driving the diamond tool 60 fixed on the tool holder to move from its current position to the initial zero point along a preset axial trajectory, completing precise zeroing positioning. In this embodiment of the invention, the coordinated operation of the tie rod 70 and the flexible hinge effectively assists the diamond tool in quickly overcoming motion inertia and eliminating positioning deviations, enabling the tool to return to the preset zero position efficiently and stably. This provides a pose initialization reference for the next cutting operation, significantly improving the continuity of the machining process.

[0068] When the diamond tool 60 reaches the zero position (the preset initial position), the flexible hinge 23 returns to its initial undeformed state under the action of the tie rod, thus ensuring that the diamond tool 60 is stably stopped at the zero position. At this time, the diamond tool 60 completes a complete cutting cycle and enters the preparation stage for the next cutting cycle. That is, according to the target pose of the diamond tool reset by the user, the static and dynamic control quantities of the piezoelectric actuator group are calculated, the piezoelectric actuator group 40 enters the standby state, and the coupling mechanisms of each axis complete the initialization synchronization, laying the foundation for the cutting operation of the next cycle, thus forming a control flow from machining to reset to remachining.

[0069] This invention achieves high-precision pose adjustment by acquiring the current pose of the diamond tool and calculating the static control quantities of the piezoelectric actuators, effectively improving machining accuracy. During pose adjustment, limiting the number of piezoelectric actuators participating in the adjustment of each control surface avoids coordination problems and error accumulation, reduces coupling interference, and further improves the accuracy of pose adjustment. Furthermore, this invention employs an elliptical cutting method, dividing the axis into an elliptical axis and a feed axis to generate dynamic control quantities, enabling efficient elliptical cutting. This invention comprehensively controls the piezoelectric actuators using both static and dynamic control quantities, fully leveraging the advantages of precise positioning and real-time adjustment, thereby improving machining efficiency and product quality.

[0070] In some embodiments, such as Figure 7 As shown, step S100 in the aforementioned embodiment, which calculates the static control quantity of each piezoelectric actuator based on the current pose parameters and target pose parameters of the diamond tool, includes the following steps:

[0071] S110: The pose parameters of the control surface 30 are obtained through the displacement sensor. Based on the coupling mapping relationship between the control surface 30 and the diamond tool 60, the pose parameters of the diamond tool 60 are determined.

[0072] In this embodiment of the invention, the position and pose parameters of the control surface 30 are obtained through a displacement sensor, which can be achieved in the following way:

[0073] (1) Obtain the position coordinates of the center points of the first control surface, the second control surface and the third control surface in the three-dimensional rectangular coordinate system.

[0074] In specific embodiments of the present invention, such as Figure 8 As shown, the coordinates of the center point a(x) of the first control plane are... a ,y a ,z a It can be calculated using the following formula:

[0075] (1)

[0076] (2)

[0077] (3)

[0078] Among them, (x a1 ,y a1 ,z a1 (x) represents the coordinates of the contact point between the first control surface and the first piezoelectric actuator a1. a2 ,y a2 ,z a2 (x) represents the coordinates of the contact point between the first control surface and the second piezoelectric actuator a2. a3 , y a3, z a3 ) represents the coordinates of the contact point between the first control surface and the third piezoelectric actuator a3. Δa1, Δa2, and Δa3 represent the elongation changes of the first piezoelectric actuator a1, the second piezoelectric actuator a2, and the third piezoelectric actuator a3 along the x-axis.

[0079] In this embodiment of the invention, the coordinates of the center point 'a' of the first control surface in the x-axis direction are dynamically changing, while the coordinates in the y-axis and z-axis directions are preset fixed values. Therefore, y a and z a The coordinate values ​​can be expressed by the following formula:

[0080] (4)

[0081] (5)

[0082] Based on the above formula, the final coordinates of the center point a(x) of the first control surface will be determined. a ,y a ,z a ) is represented as (x a ,a y ,a z Similarly, the center point coordinates b(x) of the second control surface can be obtained. b ,y b ,z b ) is represented as (a x ,y b ,c z The center point coordinates of the third control surface are c(x). c ,y c ,z c ) is represented as (a x ,b y ,z c This allows us to obtain the position coordinates of the center points of the first, second, and third control surfaces in a three-dimensional rectangular coordinate system.

[0083] (2) Obtain the attitude parameters of the first control surface, the second control surface and the third control surface in the three-dimensional rectangular coordinate system.

[0084] In this embodiment of the invention, as an example, and taking the first control surface as an example, the attitude of the first control surface is determined by the normal vector n of the first control surface. a (n a1 ,n a2 ,n a3 This can be calculated using the following formula:

[0085] (6)

[0086] (7)

[0087] (8)

[0088] Wherein, the normal vector n of the first control surface a The components along the x and z axes are dynamically changing, while the component along the y axis is a preset fixed value. Therefore, y a and z a The coordinate values ​​can be expressed by the following formula:

[0089] (9)

[0090] Based on the above formula, the attitude parameters (n) of the first control surface are finally obtained. a1 ,a n2 ,n a3 Similarly, the attitude parameters (n) of the second control surface can be obtained. b1 ,b n2 ,n b3 The attitude parameters n of the third control surface c (n c1 ,c n2 ,n c3 ).

[0091] (3) Based on the above position coordinates and attitude parameters, obtain the pose representation of the first control surface, the second control surface and the third control surface in the three-dimensional rectangular coordinate system.

[0092] In this embodiment of the invention, after obtaining the position coordinates and attitude parameters of the first control surface, the second control surface, and the third control surface, the position input matrix and attitude input matrix of the three control surfaces are obtained.

[0093] Specifically, the position input matrix of the three control surfaces can be represented as:

[0094] (10)

[0095] The attitude input matrix can be represented as:

[0096] (11)

[0097] Where 'a' represents the coordinates of the center point 'a' of the first control surface, and 'n' represents the coordinates of the center point 'a' of the first control surface. a represents the plane normal vector of the first control surface. b represents the coordinates of the center point b of the second control surface, n b Let represent the plane normal vector of the second control surface. Let c represent the coordinates of point c, the center of the third control surface, and n... c This represents the plane normal vector of the third control surface.

[0098] In this embodiment of the invention, the coupling mapping relationship between the control surface 30 and the diamond tool 60 is constructed based on the relative displacement between the control surface 30 and the tool holder 10 measured by the displacement sensor, and is used to calculate the static control quantity of each piezoelectric actuator 40.

[0099] After obtaining the pose representations of the first, second, and third control surfaces in a three-dimensional Cartesian coordinate system, the pose parameters of the diamond tool 60 are determined based on the obtained pose parameters according to the coupling mapping relationship between the control surface 30 and the diamond tool 60. Specifically, the coordinates of the first diagonal position of the tool holder 10 are set as the coordinates of the diamond tool 60. As an example, these coordinates are represented as O(x O ,y O ,z O Based on these coordinates, the position input matrix and attitude input matrix of the diamond tool 60 are determined. The position input matrix can be expressed as:

[0100] (12)

[0101] The attitude input matrix can be represented as:

[0102] (13)

[0103] Wherein, k1 is the position adjustment parameter matrix and k2 is the attitude adjustment parameter matrix. k1 and k2 can be determined by the measurement data results of the displacement sensor. Specifically, at least three sets of measurement data are collected by the displacement sensor, and the measurement data are substituted into the preset equations (12) and (13). The equations are solved with the position control coefficient k1 and attitude control coefficient k2 as unknowns to obtain the numerical solutions of parameter matrices k1 and k2.

[0104] S120: Based on the target position parameters and current position parameters of the diamond tool 60, the position adjustment amount of each piezoelectric actuator 40 is calculated through the coupling mapping relationship.

[0105] In this embodiment of the invention, after obtaining the target position parameters and current position parameters of the diamond tool 60, the position adjustment amount of each group of piezoelectric actuators 40 is calculated through a coupling mapping relationship. Specifically, the three piezoelectric actuators in each group are kept at equal output lengths, i.e., Δa1=Δa2=Δa3, Δb1=Δb2=Δb3, Δc1=Δc2=Δc3. The target position coordinates of the diamond tool are substituted into the following formula:

[0106] (12)

[0107] By solving the inverse of formula (12), the position adjustment amounts Δa, Δb, and Δc of the three sets of piezoelectric actuators are obtained.

[0108] S130: Based on the target attitude parameters and current attitude parameters of the diamond tool, calculate the attitude adjustment amount of each piezoelectric actuator through a nonlinear attitude decoupling algorithm.

[0109] In this embodiment of the invention, after obtaining the target attitude parameters and current attitude parameters of the diamond tool 60, an attitude control matrix for the diamond tool is established. A nonlinear attitude decoupling algorithm is used to calculate the attitude adjustment amount of each piezoelectric actuator. Specifically, the attitude control matrix of the diamond tool 60 is represented as follows:

[0110] (14)

[0111] Wherein, the α matrix represents the change in the attitude matrix after position adjustment. The α matrix represents a fixed value, specifically, the α matrix can be expressed as:

[0112]

[0113] In this embodiment of the invention, the attitude adjustment amount of the piezoelectric actuator required for attitude control is solved by formula (14), thereby realizing attitude compensation or active adjustment of the diamond tool.

[0114] When calculating the attitude adjustment of each piezoelectric actuator using a nonlinear attitude decoupling algorithm, specifically, the desired function is constructed as follows:

[0115] (15)

[0116] Furthermore, the Levenberg-Marquardt nonlinear estimation algorithm is used to solve the expectation function under preset constraints, thereby obtaining the optimal solution Δa for the attitude adjustment of the piezoelectric actuator. i ´、Δa j ´、Δb m ´、Δb n ´、Δc k ´、Δc l ´.

[0117] In this embodiment of the invention, the number of piezoelectric actuators used for attitude adjustment on each control surface is set to at least two. Specifically, it can be set to two or three. Configuring at least two piezoelectric actuators on each control surface for attitude adjustment ensures that the plane provides independent degrees of freedom for attitude adjustment in its own dimension. When at least six piezoelectric actuators participate in the adjustment across the three control surfaces, it can form an adjustment capability covering all orthogonal directions in three-dimensional space, meeting the minimum drive requirements for attitude parameter decoupling and precise control in a redundant system.

[0118] S140: The position adjustment amount and the attitude adjustment amount are superimposed to generate the static control amount for each piezoelectric actuator 40.

[0119] In this embodiment of the invention, the static control quantity of the piezoelectric actuator is formed by superimposing the position adjustment component and the attitude adjustment component. Specifically, the output quantity of the piezoelectric actuator group of the first control surface during the position adjustment stage is calculated by equation (12) and denoted as Δa; the output quantity during the attitude adjustment stage is calculated by equation (14) and denoted as Δa'. Figure 9 As shown, to achieve complete adjustment of the diamond tool's position and orientation, the static control quantity of the piezoelectric actuator on the first control surface is the algebraic sum of the position adjustment component and the attitude adjustment component, i.e., Δa + Δa'. Similarly, the static control quantities of the piezoelectric actuators on the second and third control surfaces can be obtained. Thus, when the piezoelectric actuators are driven according to the calculated static control quantities, the linear motion and coupled deflection motion of the three orthogonal control surfaces achieve synchronous adjustment of the diamond tool's position and orientation, thereby improving the control accuracy and response efficiency of the diamond tool.

[0120] In some embodiments, when generating the dynamic control quantity of the piezoelectric actuator according to the preset motion trajectory parameters in step S300, the dynamic control components of the dynamic control quantity of the piezoelectric actuator on each axis in the three-dimensional Cartesian coordinate system can be obtained according to the preset motion trajectory parameters, thereby obtaining the dynamic control quantity of the piezoelectric actuator. Specifically, the dynamic control components of the dynamic control quantity of the piezoelectric actuator on each axis in the three-dimensional Cartesian coordinate system are calculated according to the preset motion trajectory parameters and the position input matrix of the diamond tool.

[0121] When calculating the dynamic control components of the piezoelectric actuator along each axis in a three-dimensional Cartesian coordinate system, specifically, the dynamic control quantity of the piezoelectric actuator is substituted into the position input matrix of the diamond tool, and then the dynamic control components of the piezoelectric actuator are solved based on the preset motion trajectory parameters. The position input matrix of the diamond tool can be expressed as:

[0122] (16)

[0123] Among them, A x sin wt represents the dynamic control component of the piezoelectric actuator in the x-axis direction, A y cos wt represents the dynamic control component of the piezoelectric actuator in the y-axis direction, A z This represents the dynamic control component of the piezoelectric actuator in the z-axis direction. In this case, the dynamic control quantity of the piezoelectric actuator can be expressed as:

[0124] (17)

[0125] In some embodiments, such as Figure 10As shown, step S400 in the aforementioned embodiment, which dynamically drives the diamond tool at the target pose based on the generated dynamic control quantity, includes the following steps:

[0126] S410: Set the Z-axis as the feed axis, and control a group of piezoelectric actuators to maintain synchronous elongation motion based on the dynamic control components on the Z-axis to perform linear feed.

[0127] In this embodiment of the invention, the Z-axis is set as the feed axis. Based on the dynamic control component of the generated piezoelectric actuator dynamic control quantity on the Z-axis, a group of piezoelectric actuators along the Z-axis are controlled to perform synchronous elongation motion, thereby driving the diamond tool 60 to complete precise displacement in the feed direction. Specifically, the piezoelectric actuator group in the Z-axis direction consists of the seventh piezoelectric actuator c1, the eighth piezoelectric actuator c2, and the ninth piezoelectric actuator c3 corresponding to the third control surface. These three are arranged in an equilateral triangle. This layout can form a stable force balance during movement, effectively avoiding trajectory deviation caused by unilateral force. During movement, the seventh piezoelectric actuator c1, the eighth piezoelectric actuator c2, and the ninth piezoelectric actuator c3 receive the same drive control command according to the dynamic control component on the Z-axis, ensuring that the three perform synchronous elongation or contraction motions with consistent displacement. When the piezoelectric actuator group moves synchronously in the Z-axis direction, the piezoelectric actuator group drives the third control surface to move smoothly in the Z-axis direction through the drive hinge 21. The third control surface then drives the tool holder 10 to move in the same direction through the coupling hinge 22, thereby realizing the smooth and precise linear feed motion of the diamond tool 60 in the Z-axis direction.

[0128] S420: Set the X and Y axes as elliptical motion axes, and control the two sets of piezoelectric actuators on the X and Y axes to synchronously perform periodic elliptical trajectory motion with sine and cosine coupling according to the dynamic control components on the X and Y axes.

[0129] In this embodiment of the invention, the X and Y axes are set as elliptical motion axes. Based on the dynamic control components on the X and Y axes of the generated piezoelectric actuators, a group of piezoelectric actuators along the Z axis are controlled to perform synchronous elongation motion, thereby driving the diamond tool 60 to perform a periodic elliptical trajectory motion in the XY plane with sinusoidal and cosine coupling. Specifically, during the motion, the first piezoelectric actuator a1, the second piezoelectric actuator a2, and the third piezoelectric actuator a3 in the X-axis direction receive drive control commands for elongation and contraction according to a sine function based on the dynamic control components on the X-axis. Their displacement changes sinusoidally with time, i.e., starting from the initial position, they gradually elongate to the maximum displacement, then slowly contract back to the initial position, then continue to contract to the maximum displacement in the opposite direction, and finally elongate back to the initial position, forming a complete sinusoidal periodic motion. Meanwhile, the fourth piezoelectric actuator b1, the fifth piezoelectric actuator b2, and the sixth piezoelectric actuator b3 in the Y-axis direction receive drive control commands for motion according to a cosine function based on the dynamic control components on the Y-axis. Their displacement changes have a 90-degree phase difference with the sinusoidal motion of the X-axis.

[0130] During dynamic driving, the X and Y axes serve as elliptical motion axes, and their corresponding two sets of piezoelectric actuators continuously perform periodic movements coupled with sine and cosine motions under the control of dynamic parameters. This motion causes the diamond tool to form a stable elliptical trajectory in the XY plane. The major and minor axes of the ellipse, as well as the rotation angle, are adjusted in real time according to machining requirements to ensure that the contact state between the cutting edge and the workpiece always meets the process standards. Simultaneously, the Z axis serves as the feed axis, and its corresponding piezoelectric actuator group extends synchronously according to the feed rate set by the dynamic control parameters. This extension motion is not independent but precisely coordinated with the elliptical motion in the XY plane. Each time an elliptical cycle is completed, the Z axis drives the diamond tool to advance axially by a preset feed amount. This embodiment of the invention, through the composite mode of elliptical motion and axial feed, allows the diamond tool's cutting trajectory to naturally form a spiral progression, ensuring the stability and accuracy of helical elliptical cutting.

[0131] The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the scope of disclosure involved in the above embodiments is not limited to technical solutions formed by specific combinations of the above technical features, but should also cover other technical solutions formed by arbitrary combinations of the above technical features or their equivalent features without departing from the above-disclosed concept. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0132] Furthermore, while the operations are described in a specific order, this should not be construed as requiring these operations to be performed in the specific order shown or in sequential order. In certain circumstances, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of the invention. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

Claims

1. A servo device for rapid elliptical cutting tools, characterized in that, include: Tool holder, hinge, control surface, piezoelectric actuator, displacement sensor, diamond tool, tie rod, triaxial frame; The tool holder is connected to the control surface via a hinge. The piezoelectric actuator is located on the control surface opposite to the tool holder, with one end connected to the control surface via the hinge and the other end connected to the triaxial frame. The displacement sensor is located between the control surface and the tool holder to measure the relative displacement between the control surface and the tool holder surface. The diamond tool is located at a first diagonal position of the tool holder. One end of the diagonal tie rod is connected to a second diagonal position of the tool holder via a hinge, and the other end is connected to the triaxial frame. The hinge includes a drive hinge, a coupling hinge, and a flexible hinge. The drive hinge connects the control surface to the piezoelectric actuator, the coupling hinge connects the control surface to the tool holder, and the flexible hinge connects the diagonal tie rod to the tool holder. Each control surface opposite to the tool holder is connected to a group of piezoelectric actuators via three drive hinges arranged in an equilateral triangle. A group of piezoelectric actuators includes three piezoelectric actuators arranged in an equilateral triangle.

2. The elliptical cutting rapid tool servo device according to claim 1, characterized in that, The tool holder includes three orthogonally distributed mounting surfaces, each of which is connected to the corresponding control surface via four square-distributed coupling hinges.

3. The elliptical cutting rapid tool servo device according to claim 2, characterized in that, The first diagonal position and the second diagonal position are spatially diagonally distributed; Three displacement sensors are disposed between each of the control surfaces and each of the mounting surfaces, and the three displacement sensors are arranged in an equilateral triangle.

4. A motion control method for an elliptical cutting rapid tool servo device as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Based on the current pose parameters and target pose parameters of the diamond tool, the static control quantity of each piezoelectric actuator is calculated respectively. The piezoelectric actuator is driven to work according to the calculated static control quantity, so that the piezoelectric actuator adjusts the diamond tool in the current pose to the target pose. The dynamic control quantity of the piezoelectric actuator is generated according to the preset motion trajectory parameters; The diamond tool located at the target pose is dynamically driven and controlled according to the generated dynamic control quantity, so that the diamond tool performs an elliptical cutting motion with a spiral advance. When the diamond tool completes its cutting cycle or reaches the reset position, it is moved to the zero position via the hinge under the action of the tie rod.

5. The motion control method according to claim 4, characterized in that, The steps for calculating the static control quantity of each piezoelectric actuator based on the current pose parameters and target pose parameters of the diamond tool include: The position and pose parameters of the control surface are obtained through the displacement sensor, and the position and pose parameters of the diamond tool are determined based on the obtained position and pose parameters according to the coupling mapping relationship between the control surface and the diamond tool. Based on the target position parameters and current position parameters of the diamond tool, the position adjustment amount of each group of piezoelectric actuators is calculated through the coupling mapping relationship; Based on the target attitude parameters and current attitude parameters of the diamond tool, the attitude adjustment amount of each group of piezoelectric actuators is calculated using a nonlinear attitude decoupling algorithm. The position adjustment amount and the attitude adjustment amount are superimposed to generate the static control amount for each piezoelectric actuator.

6. The motion control method according to claim 5, characterized in that, The step of dynamically driving the diamond tool located at the target pose based on the generated dynamic control quantity includes: The Z-axis is set as the feed axis, and the group of piezoelectric actuators to which the Z-axis is located is controlled to maintain synchronous elongation motion according to the dynamic control component on the Z-axis to perform linear feed; The X-axis and Y-axis are set as elliptical motion axes, and the two sets of piezoelectric actuators on the X-axis and Y-axis are controlled to synchronously perform periodic elliptical trajectory motion with sine and cosine coupling according to the dynamic control components on the X and Y axes.

7. The motion control method according to claim 5, characterized in that, The coupling mapping relationship between the control surface and the diamond tool is constructed based on the relative displacement between the control surface and the tool holder measured by the displacement sensor.

Images