Elliptical cutting rapid cutter servo device and motion control method thereof

Abstract

The invention is suitable for the technical field of computers, and provides an ellipse cutting rapid tool servo device and a motion control method thereof.The device comprises a tool fixing base, a hinge, a control face, a piezoelectric actuator, a displacement sensor, a diamond tool, a diagonal draw bar and a three-axis frame, the tool fixing base is connected with the control face through the hinge, and the control face is connected with the piezoelectric actuator; the piezoelectric actuator is arranged on the other side, away from the cutter fixing base, of the control face, one end of the piezoelectric actuator is connected with the control face through a hinge, the other end of the piezoelectric actuator is connected with the three-axis frame, the displacement sensor is arranged between the control face and the cutter fixing base, and the diamond cutter is arranged at the first diagonal position of the cutter fixing base. One end of the diagonal draw bar is connected to the second diagonal position of the cutter fixing seat through a hinge, and the other end is connected with the three-axis frame. Independent adjustment of the position and the posture of the diamond cutter under multiple degrees of freedom is achieved, and the posture control precision of the diamond cutter during machining is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of workpiece processing, and in particular relates to an elliptical cutting fast tool servo device and a motion control method thereof. Background Art

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

[0003] Currently, FTS has undergone a development process from single-degree-of-freedom to multi-degree-of-freedom. Single-degree-of-freedom FTS processing has its limitations, namely, it can only perform unidirectional reciprocating motion and unidirectional motion axis error correction, and can only meet the needs of constant feed tool paths. It is helpless for some complex surfaces. Therefore, based on the single-degree-of-freedom FTS, multi-degree-of-freedom FTS was proposed for fast servo processing of complex surfaces. Multi-degree-of-freedom FTS can realize multi-directional active cutting processing and multi-directional displacement compensation, can solve cutting force disturbances, achieve synchronization and coordination between the machine tool spindle and the FTS device, overcome the problems existing in single-degree-of-freedom FTS processing, and expand the scope and processing capabilities of FTS diamond turning based on NRS surface processing. Therefore, the research on multi-degree-of-freedom FTS devices is of great significance.

[0004] The classic FTS machining mechanism used in existing FTS machining devices employs an FTS device mounted on the X-axis guide rail of an ultra-precision CNC lathe, with a diamond tool clamped thereon and the workpiece mounted on the spindle or shaft of the ultra-precision lathe. The FTS drives the diamond tool to achieve rapid reciprocating motion along the spindle and also to feed along the guide rails in the X and Z directions. During machining, the tool simultaneously feeds along the X and Z guide rails and rapidly reciprocates along the spindle, driven by the FTS. These two motions operate simultaneously, compensating for guide rail displacement errors, achieving macro- and micro-combination and improving the machining accuracy of the diamond tool. However, due to the characteristic of specialized machine tools, which can only process a single type of part, FTS machining devices lack versatility, resulting in high machining costs and low production efficiency. Furthermore, existing FTS machining devices typically only support limited degrees of freedom (DOF) motion adjustment, such as linear displacement or rotation in a single direction. This makes it difficult to compensate for multi-DOF diamond tool posture errors and, consequently, to meet the precise workpiece posture adjustment requirements for complex curved surface machining. Existing FTS machining devices focus on strengthening rigidity in the machining direction to meet the cutting force requirements in that direction, while paying insufficient attention to rigidity in non-machining directions. This makes it difficult to guarantee absolute rigidity in other directions, and the workpiece is prone to slight displacement or deformation in these directions, thus affecting machining accuracy and surface quality. Furthermore, diamond tools have a limited operating range, making them difficult to handle for machining complex curved surfaces with large deformations. Summary of the Invention

[0005] The purpose of the present invention is to provide an elliptical cutting fast tool servo device and a motion control method thereof, aiming to solve the problem that the existing technology has insufficient freedom of tool posture control, which makes it difficult to meet the requirements of high-precision complex surface processing.

[0006] In a first aspect, the present invention provides an elliptical cutting fast tool servo device, comprising: a tool holder, a hinge, a control surface, a piezoelectric driver, a displacement sensor, a diamond tool, an inclined rod, and a three-axis frame; In which, the tool fixing seat is connected to 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, and one end of the piezoelectric driver is connected to the control surface through the hinge, and the other end is connected to the three-axis frame, the displacement sensor is arranged in the middle of the control surface and the tool fixing seat, and is used to measure the relative displacement between the control surface and the surface of the tool fixing seat, the diamond tool is arranged at the first diagonal position of the tool fixing seat, one end of the inclined rod is connected to the second diagonal position of the tool fixing seat through the hinge, and the other end is connected to the three-axis frame.

[0007] In some embodiments, the hinge includes a driving hinge, a coupling hinge and a flexible hinge, wherein the driving hinge is used to connect the control surface and the piezoelectric driver, the coupling hinge is used to connect the control surface and the tool fixing seat, and the flexible hinge is used to connect the inclined rod and the tool fixing seat.

[0008] In some embodiments, the tool fixing seat includes three orthogonally distributed mounting surfaces, and each of the mounting surfaces is connected to the corresponding control surface via four coupling hinges distributed in a square shape.

[0009] In some embodiments, each of the control surfaces is connected to a group of the piezoelectric drivers via three driving hinges distributed in a regular triangle on the other side away from the tool fixing seat.

[0010] In some embodiments, the group of piezoelectric drivers includes three piezoelectric drivers distributed in a regular triangle shape.

[0011] In some embodiments, the first diagonal position and the second diagonal position are spatially diagonally distributed; Three displacement sensors are arranged between each control surface and each mounting surface, and the three displacement sensors are distributed in an equilateral triangle.

[0012] In a second aspect, the present invention provides a motion control method for the elliptical cutting fast tool servo device as described above, comprising the following steps: Calculating the static control amount of each piezoelectric actuator according to the current posture parameter and the target posture parameter of the diamond tool; driving the piezoelectric driver to operate according to the static control amount obtained by calculation, so that the piezoelectric driver adjusts the diamond tool at a current posture to a target posture; Generating a dynamic control variable of the piezoelectric driver according to preset motion trajectory parameters; Dynamically driving and controlling the diamond tool located at the target posture according to the generated dynamic control amount, so that the diamond tool performs a spirally advancing elliptical cutting motion; When the diamond tool completes a cutting cycle or reaches a reset position, the diamond tool is moved to a zero position through the hinge under the drive of the inclined pull rod.

[0013] In some embodiments, the step of calculating the static control amount of each of the piezoelectric actuators according to the current posture parameters and the target posture parameters of the diamond tool includes: Acquiring the posture parameters of the control surface through the displacement sensor, and determining the posture parameters of the diamond tool based on the acquired posture parameters according to a coupling mapping relationship between the control surface and the diamond tool; Calculating the position adjustment amount of each group of the piezoelectric actuators according to the target position parameter and the current position parameter of the diamond tool through the coupling mapping relationship; Calculating the posture adjustment amount of each group of the piezoelectric actuators according to the target posture parameters and current posture parameters of the diamond tool through a nonlinear posture decoupling algorithm; The position adjustment amount and the posture adjustment amount are superimposed to generate a static control amount of each piezoelectric driver.

[0014] In some embodiments, the step of dynamically driving and controlling the diamond tool located at the target posture according to the generated dynamic control amount includes: The Z axis is set as the feed axis, and a group of piezoelectric actuators on which the Z axis is located are controlled to maintain synchronous extension motion according to the dynamic control component on the Z axis to perform linear feeding; The X-axis and the Y-axis are set as elliptical motion axes, and the two groups of piezoelectric drivers on the X-axis and the Y-axis are controlled according to the dynamic control components on the X-axis and the Y-axis to synchronously perform periodic elliptical trajectory motion with sine and cosine coupling.

[0015] 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.

[0016] An embodiment of the present invention provides an elliptical cutting fast tool servo device, which includes: a tool fixing seat, a hinge, a control surface, a piezoelectric driver, a displacement sensor, a diamond tool, an inclined rod, and a three-axis frame. Through the coordinated cooperation of the tool fixing seat, the control surface and the piezoelectric driver, combined with the hinge coupling structure, the position and posture adjustment of the diamond tool are decoupled, and the independent adjustment of the position and posture of the diamond tool under multiple degrees of freedom is achieved, thereby improving the posture control accuracy of the diamond tool during processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of a fast tool servo device for elliptical cutting provided by an embodiment of the present invention; Figure 2 is another schematic diagram of the elliptical cutting fast tool servo device provided by an embodiment of the present invention; Figure 3 It is a partial schematic diagram of the elliptical cutting fast tool servo device provided by an embodiment of the present invention; Figure 4is another partial schematic diagram of the elliptical cutting fast tool servo device provided by an embodiment of the present invention; Figure 5 This is a flow chart of a motion control method for an elliptical cutting fast tool servo device provided by an embodiment of the present invention; Figure 6 This is a schematic diagram of an elliptical cutting trajectory in a three-dimensional rectangular coordinate system provided by an embodiment of the present invention; Figure 7 is a flowchart of step S100 provided in an embodiment of the present invention; Figure 8 Schematic diagram of the spatial layout of the piezoelectric driver-first control surface provided by an embodiment of the present invention; Figure 9 This is a schematic diagram of the tool fixing seat posture change provided by an embodiment of the present invention; Figure 10 It is a flowchart of step S400 provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present 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 only used to explain the present invention and are not intended to limit the present invention.

[0019] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof. Furthermore, the terminology used in this specification is for the purpose of describing specific 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 terms do not denote any order, quantity, or importance, but are simply used to distinguish one component from another. Terms such as "connected" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positions; if the absolute position of the described objects changes, such relative positions may also change accordingly.

[0020] In order to keep the following description of the embodiments of the present invention clear and concise, detailed descriptions of some known functions and components are omitted in this specification.

[0021] The present invention provides an elliptical cutting fast tool servo device 1, please refer to Figures 1 to 5 As shown in the figure, the elliptical cutting fast tool servo device 1 includes: a tool fixing base 10, a hinge 20, a control surface 30, a piezoelectric driver 40, a displacement sensor (not shown), a diamond tool 60, an inclined rod 70 and a three-axis frame 80, wherein the tool fixing base 10 is connected to the control surface 30 through the hinge 20, the piezoelectric driver 40 is arranged on the other side of the control surface 30 away from the tool fixing base 10, and one end of the piezoelectric driver 40 is connected to the control surface 30 through the hinge 20, and the other end is connected to the three-axis frame 80, the displacement sensor is arranged between the control surface 30 and the tool fixing base 10, and is used to measure the relative displacement between the control surface 30 and the surface of the tool fixing base 10, the diamond tool 60 is arranged at a first diagonal position of the tool fixing base 10, one end of the inclined rod 70 is connected to the second diagonal position of the tool fixing base 10 through the hinge 20, and the other end is connected to the three-axis frame 80. The embodiment of the present invention decouples the position and posture adjustment of the diamond tool 60 through the coordinated cooperation of the tool fixing seat 10, the control surface 30 and the piezoelectric driver 40, combined with the coupling structure of the hinge 20, and realizes independent adjustment of the position and posture under multiple degrees of freedom, thereby improving the posture control accuracy of the diamond tool 60 during processing.

[0022] In some embodiments, the tool holder 10 has a generally cubic block structure, including three orthogonally distributed mounting surfaces, namely a first mounting surface 11, a second mounting surface 12, and a third mounting surface 13, each of which 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 perpendicular to each other, forming an orthogonal spatial structure to ensure that the 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 posture control of the diamond tool 60 in three-dimensional space.

[0023] In some embodiments, the hinge 20 includes a driving hinge 21, a coupling hinge 22 and a flexible hinge 23. The driving hinge 21 is used to connect the control surface 30 and the piezoelectric driver 40, the coupling hinge 22 is used to connect the control surface 30 and the tool fixing seat 10, and the flexible hinge 23 is used to connect the inclined rod 70 and the tool fixing seat 10.

[0024] In some embodiments, the driving hinge 21 is configured as a one-dimensional hinge structure, under which the freedom of movement of the driving hinge 21 is limited to a single direction, and is used to selectively absorb and transmit the displacement or force output generated by the piezoelectric driver 40 in a preset direction. The driving hinge 21 amplifies and couples the displacement or force output generated by the piezoelectric driver 40, thereby converting it into directional movement of the control surface 30, thereby achieving precise adjustment of the position and posture of the control surface 30, ensuring that the control surface 30 can move flexibly and precisely within a preset trajectory and angle range.

[0025] In some embodiments, the coupling hinge 22 is configured as a two-dimensional hinge structure, in which the degrees of freedom of motion of the coupling hinge 22 are restricted to two orthogonally distributed axes, selectively absorbing complex displacements within a plane. The coupling hinge 22 incorporates a multi-axis motion coupling unit that couples motion components in three orthogonal directions: X, Y, and Z. This coupled motion is then precisely applied to the tool holder 10, thereby enabling position and posture control of the diamond tool 60 in three dimensions. This allows for efficient and precise machining operations in complex machining environments, according to pre-set machining paths and posture requirements.

[0026] In some embodiments, the flexible hinge 23 can be made of an elastic material. Its elastic deformation properties allow it to absorb mechanical vibration while maintaining structural rigidity and providing the necessary freedom of movement. The flexible hinge 23 utilizes this elastic deformation property to achieve gapless and frictionless motion transmission, providing a flexible and stable connection between the diagonal brace 70 and the tool holder 10. This ensures effective force and motion transmission during system operation while reducing motion errors caused by mechanical friction and clearance.

[0027] In some embodiments, the control surface 30 includes a first control surface 31, a second control surface 32, and a third control surface 33, which are arranged orthogonally. This unique orthogonal arrangement enables independent control of X, Y, and Z axis motion, providing a foundation for precise movement of the tool holder 10 in three-dimensional space. Each control surface 30 is connected to its corresponding mounting surface via four coupling hinges 22 arranged in a square pattern. Specifically, the first control surface 31 is connected to the first mounting surface 11 via four coupling hinges 22 arranged in a square pattern, the second control surface 32 is connected to the second mounting surface 12 via four coupling hinges 22 arranged in a square pattern, and the third control surface 33 is connected to the third mounting surface 13 via four coupling hinges 22 arranged in a square pattern. This ensures more uniform and stable movement of the tool holder 10 in all directions, enabling precise motion control of the tool holder 10 in complex machining environments. Furthermore, each control surface 30 is connected to a set of piezoelectric actuators 40 on the other side of the tool holder 10, via three driving hinges 21 arranged in a regular triangle pattern. Among them, the first control surface 31, the second control surface 32 and the third control surface 33 are respectively connected to the corresponding piezoelectric driver 40 through the equilateral triangle layout of the drive hinge 21 group, achieving balanced transmission of driving force and ensuring that each control surface 30 produces precise displacement and posture adjustment under the action of the piezoelectric driver 40.

[0028] In some embodiments, the piezoelectric actuators 40 employ non-resonant piezoelectric actuators, which exhibit wideband response characteristics and precise displacement output capabilities. Each set of piezoelectric actuators consists of three independent piezoelectric actuators 40 arranged in an equilateral triangle. One end of each set of piezoelectric actuators is connected to the first control surface 31, the second control surface 32, and the third control surface 33 via three drive hinges 21 arranged in an equilateral triangle, forming a one-to-one correspondence. Upon receiving drive control instructions from a data processing unit (not shown) of the elliptical cutting fast tool servo device, the piezoelectric actuators 40 generate micro-displacements and driving forces based on the inverse piezoelectric effect, and precisely transmit these micro-displacements and driving forces to the corresponding control surfaces 30 via the drive hinges 21. This enables independent drive and compound motion control of the control surfaces 30 in the three orthogonal directions of X, Y, and Z, based on the spatial force coupling characteristics of the triangular layout. Specifically, the drive control instructions are generated by the data processing unit based on the current position and motion state data of the control surface 30 monitored in real time by the displacement sensor. The other ends of the three groups of piezoelectric actuators are connected to the three-axis frame 80, optionally, rigidly connected by screw fasteners, or using a threaded connection structure with adjustable preload force to ensure efficient transmission of driving force and structural stability.

[0029] In some embodiments, reference Figure 3The piezoelectric driver 40 includes a first piezoelectric driver a1, a second piezoelectric driver a2, a third piezoelectric driver a3, a fourth piezoelectric driver b1, a fifth piezoelectric driver b2, a sixth piezoelectric driver b3, a seventh piezoelectric driver c1, an eighth piezoelectric driver c2, and a ninth piezoelectric driver c3.

[0030] In some embodiments, displacement sensors (not shown) employ non-contact, high-precision displacement measuring elements, such as capacitive or grating sensors, and are arranged in an array in the measurement gap between each control surface 30 and the corresponding mounting surface. These sensors are used to measure the posture parameters of the control surface 30 and the tool holder 10 in real time. Specifically, three displacement sensors are arranged in an equilateral triangle pattern at the interface between the first control surface 31 and the first mounting surface 11; three displacement sensors are arranged in an equilateral triangle pattern at the interface between the second control surface 32 and the second mounting surface 12; and three displacement sensors are arranged in an equilateral triangle pattern at the interface between the third control surface 33 and the third mounting surface 13. This symmetrical and uniform distribution ensures precise displacement monitoring for the precise motion control of the elliptical cutting fast tool servo device 1 in three-dimensional space. This enables the elliptical cutting fast tool servo device of the present invention to obtain real-time motion status information of the tool holder 10 in all directions, thereby adjusting the position and posture of the tool holder 10.

[0031] In some embodiments, the diamond tool 60 is diamond-shaped, with its center of symmetry fixed to the first diagonal position of the tool holder 10 via a precision positioning mechanism. Driven by the control surface 30, the diamond tool 60 produces a precise elliptical cutting trajectory and effectively disperses cutting forces during the cutting process, reducing tool wear and improving cutting stability. Furthermore, the diamond-shaped design of the diamond tool 60 optimizes the distribution of the cutting edge, significantly improving material removal rate, surface quality, and cutting efficiency during micromachining, while effectively reducing vibration interference during machining.

[0032] In some embodiments, the diagonal brace 70 is a high-strength rod-shaped structure, preferably with a circular or rectangular cross-section. It is 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 diagonal brace 70 is elastically connected to the tool holder via a flexible hinge 23 and is attached to the second diagonal position of the tool holder 10. The second diagonal position is the geometric center point where the first, second, and third mounting surfaces 11, 12, and 13 intersect orthogonally. The second diagonal position is spatially symmetrical with the first diagonal position where the diamond tool 60 is located. The other end is securely connected to the triaxial frame 80, forming a stable mechanical support structure. The diagonal brace 70 is used to accelerate the return of the diamond tool 60 coordinates to zero, improving rapid positioning performance. Furthermore, the elastic connection between the diagonal brace 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 inclined rod 70 can also enhance the stability of the entire device 1 during high-speed cutting or complex movements, ensuring the smooth progress of the processing.

[0033] In some embodiments, the three-axis frame 80 adopts an orthogonal three-axis symmetrical structure and is composed of three mutually perpendicular and precisely machined high-strength alloy panels. The three panels are perpendicular to each other to form a stable three-dimensional orthogonal structure, which provides solid support and precise spatial positioning for the device 1. Each panel is provided with a locating pin hole and a threaded hole that precisely matches the mounting hole position of the piezoelectric driver 40. The piezoelectric driver 40 is rigidly fixed to the frame panel by a combination of locating pins and high-strength bolts. The three panels are fixedly connected to the other end of the diagonal rod 70 through a connection interface at the center point of the orthogonal intersection in space. The orthogonal center point corresponds to the second diagonal position of the tool fixing seat 10, thereby forming a stable three-dimensional mechanical support system, ensuring that the driving force generated by the piezoelectric driver 40 can be efficiently transmitted, while providing a precise positioning reference and a stable support foundation for the diagonal rod 70.

[0034] The embodiment of the present invention decouples the position and posture adjustment of the diamond tool 60 through the coordinated cooperation of the tool holder 10, the control surface 30 and the piezoelectric driver 40, combined with the coupling structure of the hinge 20, and realizes independent adjustment of the position and posture under multiple degrees of freedom, thereby improving the posture control accuracy of the diamond tool during processing. The embodiment of the present invention also accelerates the speed of the tool coordinate returning to zero position through the connection design of the inclined rod 70 and the tool holder 10, enhances the rigidity in the non-driving direction, effectively suppresses the tool offset, and improves the stability and reliability of the processing process. In addition, the embodiment of the present invention also expands the operating space of the diamond tool 60 through a unique three-dimensional spatial layout design, so that it can adapt to the processing requirements of surfaces with complex shapes and large deformations, making the cutting path of the tool in three-dimensional space more flexible, thereby enriching the tool path planning method for three-dimensional surface micro-nano processing, and further improving the processing efficiency and surface quality of the diamond tool 60.

[0035] like Figure 5 As shown, the embodiment of the present invention further provides a motion control method of the aforementioned elliptical cutting fast tool servo device, comprising the following steps: S100: Calculate the static control amount of each piezoelectric actuator 40 according to the current posture parameters and the target posture parameters of the diamond tool 60.

[0036] In an embodiment of the present invention, the current posture parameters of the diamond tool 60 include current position parameters and current posture parameters, and the target posture parameters include target position parameters and target state parameters. The target position parameters are pre-set by the user, for example, by an input device connected to the elliptical cutting fast tool servo device by wire or wireless. Specifically, the displacement sensor collects the current posture parameters of the diamond tool 60 in real time and feeds these data back to the data processing unit. The data processing unit compares and analyzes the current posture parameters with the preset target posture parameters and calculates the posture error of each degree of freedom. Based on the posture error data, the data processing unit further calculates the static control amount required by the piezoelectric actuator 40.

[0037] S200: driving the piezoelectric driver 40 to operate according to the calculated static control amount, so that the piezoelectric driver adjusts the diamond tool at the current posture to the target posture.

[0038] In an embodiment of the present invention, the piezoelectric driver 40 is driven to work according to the static control quantity obtained by calculation. The piezoelectric driver 40 transmits the driving force to the control surface 30 through the driving hinge 21, so that the control surface 30 produces a posture change. The control surface 30 then drives the tool fixing seat 10 to produce a posture change through the coupling hinge 22, thereby adjusting the diamond tool 60 from the current posture to the target posture smoothly and accurately.

[0039] S300: Generate a dynamic control variable of the piezoelectric driver according to preset motion trajectory parameters.

[0040] In an embodiment of the present invention, the preset motion trajectory parameters include dynamic characteristic parameters of the diamond tool during motion, 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, while 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 quantity components of each piezoelectric actuator group in the first control surface, the second control surface, and the third control surface are calculated, ultimately generating the dynamic control quantity of the piezoelectric actuator.

[0041] S400: Dynamically drive and control the diamond tool located at the target posture according to the generated dynamic control amount, so that the diamond tool performs a spiral forward elliptical cutting motion.

[0042] In the embodiment of the present invention, the three groups of piezoelectric actuators are controlled to move according to the generated dynamic control amount to dynamically drive and control the diamond tool at the target position. Specifically, 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 synchronously perform sine and cosine coupled motions. The three sets of piezoelectric actuators transmit the driving force generated by the motion to the control surface via the drive hinge. The control surface transmits this driving force to the tool holder via the coupling hinge, thereby driving the diamond tool on the tool holder to perform a spiral forward elliptical cutting motion in three-dimensional space, forming a smooth, continuous elliptical trajectory in the XY plane, thereby ensuring the uniformity of material removal and surface quality during elliptical cutting by the diamond tool.

[0043] 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 through the hinge 20 under the drive of the inclined rod 70.

[0044] In an embodiment of the present invention, when the diamond tool 60 completes a preset cutting cycle, or reaches a set reset position in the processing flow, the reset mechanism is triggered. This reset process realizes the precise zero positioning of the tool through the coordinated action of the diagonal rod 70 and the flexible hinge 23. Specifically, during the cutting process of the diamond tool, the flexible hinge 23 undergoes adaptive elastic deformation due to the feeding action of the diamond tool. When the diamond tool 60 completes a preset cutting cycle, or reaches a set reset position in the processing flow, the reset mechanism is triggered. At this time, the flexible hinge 23 enters the rebound stage. When the flexible hinge 23 attempts to return to its initial shape under the action of elastic deformation, this deformation will be converted into an axial tension on the diagonal rod 70. The flexible hinge 23 first applies a traction force along the axial direction of the diagonal rod 70 to drive the diagonal rod 70 to produce axial displacement. Subsequently, the inclined tie rod 70 transmits the traction force to the connected flexible hinge 23, which in turn pulls the tool holder, ultimately driving the diamond cutter 60 fixed to the tool holder to move along a preset axial trajectory from its current position to the initial zero point, completing precise zero positioning. The coordinated cooperation between the inclined tie rod 70 and the flexible hinge in this embodiment of the present invention effectively assists the diamond cutter in quickly overcoming motion inertia and eliminating positioning deviations, achieving efficient and stable return of the cutter to the preset zero position, providing a position initialization reference for the next cutting operation and significantly improving the continuity of the machining process.

[0045] When the diamond cutter 60 reaches zero (the preset initial position), the flexible hinge 23, driven by the inclined tie rod, returns to its initial, undeformed state, ensuring that the diamond cutter 60 remains stable at zero. At this point, the diamond cutter 60 completes a full cutting cycle and enters the preparation phase for the next cutting cycle. This involves calculating the static and dynamic control variables of the piezoelectric actuator assembly based on the user-set target position of the diamond cutter. The piezoelectric actuator assembly 40 enters a standby state, and the coupling mechanisms of each axis complete initial synchronization, laying the foundation for the next cutting cycle. This forms a control flow from machining to resetting to remachining.

[0046] The embodiment of the present invention achieves high-precision posture adjustment by obtaining the current posture of the diamond tool and calculating the static control amount of the piezoelectric driver, thereby effectively improving the processing accuracy. During the posture adjustment process, by limiting the number of piezoelectric drivers involved in the adjustment of each control surface, coordination problems and error accumulation are avoided, coupling interference is reduced, and the accuracy of posture adjustment is further improved. In addition, the embodiment of the present invention adopts an elliptical cutting method to divide the axis into an elliptical axis and a feed axis, and generates a dynamic control amount, which can efficiently achieve elliptical cutting. The embodiment of the present invention comprehensively controls the piezoelectric driver through static control amounts and dynamic control amounts, giving full play to the advantages of precise positioning and real-time adjustment, thereby improving processing efficiency and product quality.

[0047] In some embodiments, as Figure 7 As shown, step S100 in the aforementioned embodiment of calculating the static control amount of each piezoelectric actuator according to the current posture parameter and the target posture parameter of the diamond tool includes the following steps: S110: Acquire the posture parameters of the control surface 30 through the displacement sensor, and determine the posture parameters of the diamond tool 60 based on the acquired posture parameters according to the coupling mapping relationship between the control surface 30 and the diamond tool 60.

[0048] In the embodiment of the present invention, obtaining the posture parameters of the control surface 30 by the displacement sensor can be achieved in the following ways: (1) Obtain the position coordinates of the center points of the first control surface, the second control surface, and the third control surface in a three-dimensional rectangular coordinate system.

[0049] In the embodiment of the present invention, specifically, Figure 8 As shown, the center point coordinates a(x a ,y a ,z a ) can be calculated by the following formula: (1) (2) (3) Among them, (x a1 ,y a1 ,z a1 ) represents the coordinates of the contact point between the first control surface and the first piezoelectric driver a1, (x a2 ,y a2 ,z a2 ) represents the coordinates of the contact point between the first control surface and the second piezoelectric driver a2, (x 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 direction.

[0050] In the embodiment of the present invention, the coordinates of the center point a of the first control surface in the x-axis direction are dynamically changing, and the coordinates in the y-axis and z-axis directions are preset fixed values. Therefore, y a and z a The coordinate value can be expressed by the following formula: (4) (5) According to the above formula, the center point coordinate a(x a ,y a ,z a ) is expressed as (x a ,a y ,a z ), similarly, the center point coordinates b(x b ,y b ,z b ) is expressed as (a x ,y b ,c z ), the coordinates of the center point of the third control surface c(x c ,y c ,z c ) is expressed as (a x ,b y ,z c ), thereby obtaining 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.

[0051] (2) Obtain the attitude parameters of the first control surface, the second control surface, and the third control surface in a three-dimensional rectangular coordinate system.

[0052] In the embodiment of the present invention, as an example, taking the first control surface as an example, the posture of the first control surface is represented by the normal vector n of the first control surface. a (n a1 ,n a2 ,n a3 ) can be calculated by the following formula: (6) (7) (8) Among them, the normal vector n of the first control surface a The components in the x-axis and z-axis directions are dynamic changes, and the component in the y-axis direction is a preset fixed amount. Therefore, y a and z a The coordinate value can be expressed by the following formula: (9) According to the above formula, the attitude parameter of the first control surface (n a1 ,a n2 ,n a3 ), and similarly, the attitude parameters of the second control surface (n b1 ,b n2 ,n b3 ), attitude parameter n of the third control surface c(n c1 ,c n2 ,n c3 ).

[0053] (3) Based on the above position coordinates and attitude parameters, obtain the position and attitude representation of the first control surface, the second control surface, and the third control surface in the three-dimensional rectangular coordinate system.

[0054] In the embodiment of the present 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 the attitude input matrix of the three control surfaces are acquired.

[0055] Specifically, the position input matrix of the three control surfaces can be expressed as: (10) The posture input matrix can be expressed as: (11) Where a represents the position coordinate of the center point a of the first control surface, n a represents the plane normal vector of the first control surface. b represents the position coordinate of point b, the center of the second control surface, and n b represents the plane normal vector of the second control surface. c represents the position coordinate of the center point c of the third control surface, n c Represents the plane normal vector of the third control surface.

[0056] In the embodiment of the present invention, the coupling mapping relationship between the control surface 30 and the diamond tool 60 is constructed based on the relative displacement of the control surface 30 and the tool holder 10 measured by the displacement sensor, and is used to calculate the static control amount of each piezoelectric driver 40.

[0057] After obtaining the posture representations of the first control surface, the second control surface, and the third control surface in the three-dimensional rectangular coordinate system, the posture parameters of the diamond tool 60 are determined based on the obtained posture 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, the coordinates are expressed as O(x O ,y O ,z O ), and then determine the position input matrix and posture input matrix of the diamond tool 60 based on the coordinates, wherein the position input matrix can be expressed as: (12) The posture input matrix can be expressed as: (13) Where k1 is the position adjustment parameter matrix, and k2 is the attitude adjustment parameter matrix. k1 and k2 can be determined using the measurement data from the displacement sensor. Specifically, at least three sets of measurement data are collected using the displacement sensor, and the measurement data are substituted into the preset equations (12) and (13). The equations are solved using the position control coefficient k1 and the attitude control coefficient k2 as unknowns to obtain the numerical solutions for the parameter matrices k1 and k2.

[0058] S120 : Calculating the position adjustment amount of each group of piezoelectric drivers 40 according to the target position parameter and the current position parameter of the diamond tool 60 through a coupling mapping relationship. In this embodiment of the present 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 using a coupling mapping relationship. Specifically, the three piezoelectric actuators in each group are kept at equal length outputs, i.e., Δa1=Δa2=Δa3, Δb1=Δb2=Δb3, and Δc1=Δc2=Δc3. The target position coordinates of the diamond tool are substituted into the following formula: (12) By finding the inverse solution of formula (12), we can obtain the position adjustment values ​​Δa, Δb, and Δc of the three groups of piezoelectric actuators.

[0059] S130: Calculating the posture adjustment amount of each group of piezoelectric actuators according to the target posture parameters and current posture parameters of the diamond tool through a nonlinear posture decoupling algorithm.

[0060] In the embodiment of the present invention, after obtaining the target posture parameters and current posture parameters of the diamond tool 60, a posture control matrix of the diamond tool is established, and the posture adjustment amount of each group of piezoelectric actuators is calculated using a nonlinear posture decoupling algorithm. Specifically, the posture control matrix of the diamond tool 60 is expressed as: (14) Among them, the α matrix is ​​the change of the posture matrix after position adjustment. The α matrix represents a fixed value. Specifically, the α matrix can be expressed as: In the embodiment of the present invention, the posture adjustment amount of the piezoelectric driver required for posture control is solved by formula (14), thereby realizing posture compensation or active adjustment of the diamond tool.

[0061] When calculating the attitude adjustment amount of each group of piezoelectric actuators by the nonlinear attitude decoupling algorithm, specifically, the expectation function is constructed: (15) Furthermore, the Levenberg-Marquardt nonlinear estimation algorithm is used to solve the expected function under the preset constraints, thereby obtaining the optimal solution Δa of the posture adjustment amount of the piezoelectric actuator. i ´、Δa j ´, Δb m ´, Δb n ´, Δc k ´, Δc l ´.

[0062] In an embodiment of the present invention, the number of piezoelectric actuators participating in attitude adjustment on each control surface is set to at least two. Specifically, the number can be set to two or three. Each control surface is equipped with at least two piezoelectric actuators for attitude adjustment, ensuring that the plane provides independent attitude adjustment freedom in its dimension. When a total of at least six piezoelectric actuators are involved in adjustment across three control surfaces, adjustment capabilities covering all orthogonal directions in three-dimensional space can be achieved, meeting the minimum drive requirements for attitude parameter decoupling and precise control in a redundant system.

[0063] S140 : Superimposing the position adjustment amount and the posture adjustment amount to generate a static control amount for each piezoelectric driver 40 .

[0064] In the embodiment of the present invention, the static control quantity of the piezoelectric actuator is formed by the superposition of the position adjustment component and the attitude adjustment component. Specifically, the output of the piezoelectric actuator group of the first control surface in the position adjustment phase is calculated by equation (12) and is recorded as Δa; the output in the attitude adjustment phase is calculated by equation (14) and is recorded as Δa'. Figure 9 As shown in the figure, to achieve complete adjustment of the diamond tool's position and posture, the static control variable of the piezoelectric actuator on the first control surface is the algebraic sum of the position adjustment component and the attitude adjustment component, namely, Δa + Δa'. Similarly, the static control variables of the piezoelectric actuators on the second and third control surfaces can be derived. Thus, when the piezoelectric actuator is driven by the calculated static control variable, the linear motion of the three orthogonal control surfaces and their coupled deflection motion achieve synchronous adjustment of the diamond tool's position and posture, thereby improving the control accuracy and response efficiency of the diamond tool.

[0065] In some embodiments, when generating the dynamic control amount of the piezoelectric actuator based on the preset motion trajectory parameters in step S300, the dynamic control components of the dynamic control amount of the piezoelectric actuator on each axis in a three-dimensional rectangular coordinate system can be obtained based on the preset motion trajectory parameters, thereby obtaining the dynamic control amount of the piezoelectric actuator. Specifically, the dynamic control components of the dynamic control amount of the piezoelectric actuator on each axis in the three-dimensional rectangular coordinate system are calculated based on the preset motion trajectory parameters and the position input matrix of the diamond tool.

[0066] When calculating the dynamic control components of the piezoelectric actuator on each axis in the three-dimensional rectangular coordinate system, the dynamic control components of the piezoelectric actuator are specifically substituted into the position input matrix of the diamond tool, and then the dynamic control components of the piezoelectric actuator are solved according to the preset motion trajectory parameters. The position input matrix of the diamond tool can be expressed as: (16) 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 represents the dynamic control component of the piezoelectric actuator in the z-axis direction. At this time, the dynamic control quantity of the piezoelectric actuator can be expressed as: (17) In some embodiments, as Figure 10 As shown, step S400 in the aforementioned embodiment dynamically drives and controls the diamond tool located at the target posture according to the generated dynamic control amount, including the following steps: S410: The Z axis is set as the feed axis, and a group of piezoelectric drivers on which the Z axis is located are controlled to maintain synchronous extension motion according to the dynamic control component on the Z axis to perform linear feeding.

[0067] In an embodiment of the present invention, the Z-axis is set as the feed axis, and a group of piezoelectric drivers where the Z-axis is located is controlled to perform synchronous extension movement according to the dynamic control component on the Z-axis in the dynamic control amount of the generated piezoelectric driver, thereby driving the diamond tool 60 to complete precise displacement in the feed direction. Specifically, the piezoelectric driver group in the Z-axis direction is composed of the seventh piezoelectric driver c1, the eighth piezoelectric driver c2, and the ninth piezoelectric driver c3 corresponding to the third control surface. The three are distributed in an equilateral triangle. This layout can form a stable force balance during the movement process and effectively avoid the trajectory deviation caused by unilateral force. During the movement process, the seventh piezoelectric driver c1, the eighth piezoelectric driver c2, and the ninth piezoelectric driver c3 receive the same drive control instructions according to the dynamic control component on the Z-axis, ensuring that the three perform synchronous extension or contraction movement and the displacement remains consistent. When the piezoelectric driver group in the Z-axis direction moves synchronously, the piezoelectric driver group drives the third control surface to move smoothly along the Z-axis direction through the driving hinge 21, and the third control surface then drives the tool fixing seat 10 to move in the same direction through the coupling hinge 22, thereby realizing smooth and precise linear feed movement of the diamond tool 60 in the Z-axis direction.

[0068] S420: Setting the X-axis and the Y-axis as elliptical motion axes, and controlling the two groups of piezoelectric actuators on the X-axis and the Y-axis to synchronously perform sine-cosine coupled periodic elliptical trajectory motion according to the dynamic control components on the X-axis and the Y-axis.

[0069] In an embodiment of the present invention, the X-axis and Y-axis are set as elliptical motion axes. Based on the dynamic control components on the X and Y axes within the generated dynamic control quantities of the piezoelectric actuators, a group of piezoelectric actuators located on the Z-axis are controlled to synchronously extend, thereby driving the diamond tool 60 to perform a periodic elliptical trajectory motion coupled by sine and cosine in the XY plane. Specifically, during the motion process, the first, second, and third piezoelectric actuators a1, a2, and a3 in the X-axis direction receive drive control instructions for extension and retraction according to the sine function based on the dynamic control components on the X-axis. Their displacements exhibit a sinusoidal curve variation over time, i.e., starting from an initial position, they gradually extend to a maximum displacement, then slowly retract back to the initial position, then continue to retract to a maximum displacement in the opposite direction, and finally extend again back to the initial position, forming a complete sinusoidal periodic motion. Meanwhile, the fourth, fifth, and sixth piezoelectric actuators b1, b2, and b3 in the Y-axis direction receive drive control instructions for motion according to the cosine function based on the dynamic control components on the Y-axis. Their displacements exhibit a 90-degree phase difference from the sinusoidal motion of the X-axis.

[0070] During the dynamic drive process, the X-axis and Y-axis serve as elliptical motion axes, and their corresponding two groups of piezoelectric drivers will continue to perform sine and cosine coupled periodic motion under the control of the dynamic control amount. This motion enables the diamond tool to form a stable elliptical trajectory in the XY plane. The major axis, minor axis size and rotation angle of the ellipse will be adjusted in real time according to the processing requirements to ensure that the contact state between the cutting edge and the workpiece always meets the process standards. At the same time, the Z-axis serves as the feed axis, and its corresponding piezoelectric driver group will extend synchronously according to the feed rate set by the dynamic control amount. This extension motion is not carried out independently, but forms a precise match with the elliptical motion in the XY plane. After each elliptical cycle of motion is completed, the Z-axis will drive the diamond tool to advance axially by a preset feed amount. The embodiment of the present invention uses a composite mode of elliptical motion and axial feed to enable the cutting trajectory of the diamond tool to naturally form a spiral forward state, thereby ensuring the stability and accuracy of spiral elliptical cutting.

[0071] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the scope of disclosure involved in the above embodiments is not limited to the technical solutions formed by the specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concepts. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0072] In addition, although adopting specific order to describe each operation, this should not be interpreted as requiring these operations to be executed in the specific order shown or in sequential order.Under certain environment, multitasking and parallel processing may be advantageous.Similarly, although comprising some specific implementation details in the above discussion, these should not be interpreted as limiting the scope of the present invention.Some features described in the context of independent embodiment can also be implemented in single embodiment in combination.On the contrary, the various features described in the context of independent embodiment also can be implemented in multiple embodiments individually or in the mode of any suitable subcombination.

Claims

1. A fast tool servo device for elliptical cutting, characterized in that: include: Tool holder, hinge, control surface, piezoelectric actuator, displacement sensor, diamond tool, inclined rod, three-axis frame; In which, the tool fixing seat is connected to 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, and one end of the piezoelectric driver is connected to the control surface through the hinge, and the other end is connected to the three-axis frame, the displacement sensor is arranged in the middle of the control surface and the tool fixing seat, and is used to measure the relative displacement between the control surface and the surface of the tool fixing seat, the diamond tool is arranged at the first diagonal position of the tool fixing seat, one end of the inclined rod is connected to the second diagonal position of the tool fixing seat through the hinge, and the other end is connected to the three-axis frame.

2. The elliptical cutting fast tool servo device according to claim 1, characterized in that: The hinge includes a driving hinge, a coupling hinge and a flexible hinge. The driving hinge is used to connect the control surface and the piezoelectric driver, the coupling hinge is used to connect the control surface and the tool fixing seat, and the flexible hinge is used to connect the inclined rod and the tool fixing seat.

3. The elliptical cutting fast tool servo device according to claim 2, characterized in that: The tool fixing seat includes three orthogonally distributed mounting surfaces, and each mounting surface is connected to the corresponding control surface via four coupling hinges distributed in a square.

4. The elliptical cutting fast tool servo device according to claim 3, characterized in that: The other side of each control surface away from the tool fixing seat is connected to a group of piezoelectric drivers through three driving hinges distributed in a regular triangle.

5. The elliptical cutting fast tool servo device according to claim 4, characterized in that: The group of piezoelectric drivers includes three piezoelectric drivers distributed in a regular triangle.

6. The elliptical cutting fast tool servo device according to claim 1, characterized in that: The first diagonal position and the second diagonal position are spatially diagonally distributed; Three displacement sensors are arranged between each control surface and each mounting surface, and the three displacement sensors are distributed in an equilateral triangle.

7. A motion control method for an elliptical cutting fast tool servo device according to any one of claims 1 to 6, characterized in that: The following steps are involved: Calculating the static control amount of each piezoelectric actuator according to the current posture parameter and the target posture parameter of the diamond tool; driving the piezoelectric driver to operate according to the static control amount obtained by calculation, so that the piezoelectric driver adjusts the diamond tool at a current posture to a target posture; Generating a dynamic control variable of the piezoelectric driver according to preset motion trajectory parameters; Dynamically driving and controlling the diamond tool located at the target posture according to the generated dynamic control amount, so that the diamond tool performs a spirally advancing elliptical cutting motion; When the diamond tool completes a cutting cycle or reaches a reset position, the diamond tool is moved to a zero position through the hinge under the drive of the inclined pull rod.

8. The motion control method according to claim 7, characterized in that: The step of respectively calculating the static control amount of each of the piezoelectric actuators according to the current posture parameters and the target posture parameters of the diamond tool comprises: Acquiring the posture parameters of the control surface through the displacement sensor, and determining the posture parameters of the diamond tool based on the acquired posture parameters according to a coupling mapping relationship between the control surface and the diamond tool; Calculating the position adjustment amount of each group of the piezoelectric actuators according to the target position parameter and the current position parameter of the diamond tool through the coupling mapping relationship; Calculating the posture adjustment amount of each group of the piezoelectric actuators according to the target posture parameters and current posture parameters of the diamond tool through a nonlinear posture decoupling algorithm; The position adjustment amount and the posture adjustment amount are superimposed to generate a static control amount of each piezoelectric driver.

9. The motion control method according to claim 8, characterized in that: The step of dynamically driving and controlling the diamond tool located at the target posture according to the generated dynamic control amount includes: The Z axis is set as the feed axis, and a group of piezoelectric actuators on which the Z axis is located are controlled to maintain synchronous extension motion according to the dynamic control component on the Z axis to perform linear feeding; The X-axis and the Y-axis are set as elliptical motion axes, and the two groups of piezoelectric drivers on the X-axis and the Y-axis are controlled according to the dynamic control components on the X-axis and the Y-axis to synchronously perform periodic elliptical trajectory motion with sine and cosine coupling.

10. The motion control method according to claim 8, 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 fixing seat measured by the displacement sensor.

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