Magnetic levitation probe and method of measurement

Abstract

The application provides a magnetic suspension measuring head and a measuring method, which comprise a shell, an upper magnetic ring, a lower magnetic ring, a rigid mover and an FDM2 displacement sensor; the shell comprises an upper shell and a lower shell; the upper magnetic ring is fixedly installed on the upper shell, and the lower magnetic ring is fixedly installed on the lower shell; the upper magnetic ring and the lower magnetic ring are located in the shell; the rigid mover comprises a measuring needle disc and a measuring needle; the measuring needle disc is located between the upper magnetic ring and the lower magnetic ring; the measuring needle disc has magnetism, and the measuring needle disc and the upper magnetic ring and the lower magnetic ring have repulsion force so that the measuring needle disc is stably suspended between the upper magnetic ring and the lower magnetic ring; the measuring needle is installed at the bottom of the measuring needle disc, and the lower end of the measuring needle extends out of the lower shell; the measuring needle does not contact the lower shell; and the FDM2 displacement sensor is fixedly installed on the upper shell. The application can improve the response sensitivity and repeatability of the measuring head to weak contact force, and meet the low-damage contact measurement requirements of complex curved surfaces, small structures and soft and brittle material surfaces in the process of ultra-high-precision three-dimensional measurement.

Description

Technical Field

[0001] This application relates to the field of measurement technology, and in particular to a magnetic levitation probe and measurement method. Background Technology

[0002] A profilometer, also known as a profilometer, is an instrument that measures the true shape and comprehensive characteristics of the surface profile of an object using a contact probe. In practical applications, the probe is typically made of diamond or other high-hardness materials. During measurement, the probe moves laterally across the surface of the object and undergoes vertical undulations in accordance with the geometric contours of the object's surface. The profilometer's sensor detects the vertical displacement of the probe and outputs an electrical signal that matches the contour of the object, thereby obtaining the surface profile parameters of the object.

[0003] Traditional contact probes, with their mechanical springs, sliding guides, or flexible hinges, are prone to introducing friction, hysteresis, and backlash errors. Traditional contact probes are no longer sufficient to meet the low-damage contact measurement requirements of complex curved surfaces, microstructures, and soft, brittle material surfaces in ultra-high precision 3D measurement processes. Summary of the Invention

[0004] The purpose of this application is to provide a magnetic levitation probe and measurement method to overcome the shortcomings of the prior art. It can realize weak contact force sensing, complex curved surface following and probe safety protection, and meet the low-damage contact measurement requirements of complex curved surfaces, microstructures and soft and brittle material surfaces in ultra-high precision three-dimensional measurement process.

[0005] This application provides a magnetic levitation probe including a housing, an upper magnetic ring, a lower magnetic ring, a rigid mover, and an FDM2 displacement sensor; The housing includes an upper housing and a lower housing; the upper magnetic ring is fixedly mounted on the upper housing and the lower magnetic ring is fixedly mounted on the lower housing; both the upper magnetic ring and the lower magnetic ring are located inside the housing; The rigid mover includes a probe disk and a probe; the probe disk is located between the upper magnetic ring and the lower magnetic ring; the probe disk is magnetic, and the probe disk has a repulsive force with both the upper and lower magnetic rings to stably suspend the probe disk between the upper and lower magnetic rings; the probe is installed at the bottom of the probe disk, and the lower end of the probe extends out of the lower housing; the probe does not contact the lower housing. The FDM2 displacement sensor is fixedly installed on the upper housing. The FDM2 displacement sensor measures the vertical displacement of the probe disk, and the measured value is used to calculate the vertical displacement of the probe tip. There are at least three FDM2 displacement sensors, which are distributed along the circumferential direction of the probe disk.

[0006] Preferably, it further includes a measurement and control unit, which is used to receive the measurement value of the FDM2 displacement sensor and calculate the vertical displacement of the probe tip based on the measurement value of the FDM2 displacement sensor.

[0007] Preferably, there are three FDM2 displacement sensors, which are evenly distributed along the circumferential direction of the probe disk and are vertically arranged.

[0008] Preferably, the formula for calculating the vertical displacement of the probe tip is: ;in, This represents the axial displacement of the rigid mover reference point. The small tilt angle of the rigid mover about the X-axis; For the small tilt angle of the rigid mover about the Y-axis; Let be the lateral coordinate of the probe tip relative to the rigid mover reference point. The coordinates of the probe tip relative to the rigid mover reference point are given.

[0009] Preferably, the ; ; in, These are the measurements from three FDM2 sensors; The installation radius is for the three FDM2 units.

[0010] Preferably, the probe disc and the probe are both made of ferromagnetic material; the rigid mover also includes a permanent magnet 9; the permanent magnet 9 is fixedly sleeved on the probe, and the permanent magnet 9 is located below the lower housing; a magnetic shielding element 8 is provided between the permanent magnet 9 and the lower housing.

[0011] Preferably, the magnetic shielding component 8 includes a sleeve 81 and a retaining ring 82; the sleeve 81 is provided with a clearance hole at one end near the probe disk for the probe to pass through; the permanent magnet 9 is located inside the sleeve 81 and does not contact the sleeve 81; the retaining ring 82 is fixedly disposed at one end of the sleeve 81 away from the probe disk, and the retaining ring 82 is fixedly connected to the lower housing.

[0012] Preferably, the lower housing has a mounting hole for mounting the sleeve 81, and the sleeve 81 is located in the mounting hole.

[0013] This application provides a measurement method for the magnetically levitated probe described above, comprising the following steps: S1. Vertically install the magnetic levitation probe on the Z-axis feed mechanism; S2. Control the probe tip to contact the surface of the workpiece to be measured; control the Z-axis feed mechanism to move to drive the magnetic levitation probe to move, so that the probe tip moves along the surface of the workpiece to measure, while the FDM2 displacement sensor acquires the vertical displacement of the probe disk in real time. S3. Calculate the vertical displacement value of the probe tip based on the measurement value of the FDM2 displacement sensor; S4. Compare the vertical displacement value of the probe tip with the pre-calibrated safety threshold of the probe tip; when the vertical displacement value of the probe tip exceeds the safety threshold, control the Z-axis feed mechanism to stop feeding or retreat for protection.

[0014] Preferably, step S4 includes: S41: Compare the vertical displacement value of the probe tip with the pre-calibrated warning threshold of the probe tip; when the vertical displacement value of the probe tip does not exceed the warning threshold, control the Z-axis feed mechanism to continue moving, and the probe tip continues to measure along the surface of the workpiece. S42: When the vertical displacement value of the probe tip exceeds the warning threshold but does not exceed the full threshold, control the Z-axis feed mechanism to reduce the feed speed or pause and trigger an alarm; S43: When the vertical displacement value of the probe tip exceeds the safety threshold, control the Z-axis feed mechanism to stop moving or retract for protection.

[0015] Compared with the prior art, this application has the following beneficial effects. This application employs an upper and lower magnetic ring, a rigid mover, and an FDM2 displacement sensor. The asymmetric combined magnetic field formed by the upper and lower magnetic rings, together with the gravity of the rigid mover, constitutes a low-stiffness flexible support. This allows the probe to generate a measurable minute displacement response when it contacts the workpiece surface. The FDM2 displacement sensor measures the displacement of the rigid mover, and the vertical displacement of the probe tip is calculated based on the measured value. This structure avoids the friction and viscosity effects of traditional contact-type mechanical elastic supports, improves the probe's response sensitivity and repeatability to weak contact forces, and meets the low-damage contact measurement requirements for complex curved surfaces, microstructures, and soft and brittle material surfaces in ultra-high precision three-dimensional measurement processes. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 An exploded view of the magnetic levitation probe provided in an embodiment of this application.

[0018] Figure 2 This is a cross-sectional view of the magnetic levitation probe provided in an embodiment of this application.

[0019] Figure 3 This is a diagram showing the relationship between magnetic force and displacement, and the design of the working area.

[0020] Figure 4 A flowchart of the measurement method provided in the embodiments of this application.

[0021] Figure 5 This is a flowchart of step S4.

[0022] Figure 6 This is an FDM2 white light interferometry method.

[0023] 1-Upper housing, 2-Lower housing, 3-Upper magnetic ring, 4-Lower magnetic ring, 5-Probe disc, 6-Probe, 7-FDM2 displacement sensor, 8-Magnetic shield, 81-Sleeve, 82-Retaining ring, 9-Permanent magnet. Detailed Implementation

[0024] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0025] In the description of this invention, it should be understood that the terms "longitudinal," "lateral," "thickness," "upper," "lower," "top," "bottom," "inner," "outer," and "radial," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] Please see Figures 1-2 The magnetic levitation probe provided in this application includes a housing, an upper magnetic ring 3, a lower magnetic ring 4, a rigid mover, and an FDM2 displacement sensor 7; the housing is made of aluminum. The FDM2 displacement sensor 7 is a white light interferometric displacement sensor, a non-contact high-precision displacement sensor, whose output is the distance or displacement change between the probe and the measured reflective surface.

[0027] The housing includes an upper housing 1 and a lower housing 2; an upper magnetic ring 3 is fixedly installed on the upper housing 1 and a lower magnetic ring 4 is fixedly installed on the lower housing 2; both the upper magnetic ring 3 and the lower magnetic ring 4 are located inside the housing; the upper housing 1 and the lower housing 2 are detachably connected.

[0028] The rigid mover includes a probe disk 5 and a probe 6. The probe disk 5 is located between the upper magnetic ring 3 and the lower magnetic ring 4. The probe disk 5 is magnetic, and the probe disk 5 has a repulsive force with both the upper magnetic ring 3 and the lower magnetic ring 4, so that the probe disk 5 is stably suspended between the upper magnetic ring 3 and the lower magnetic ring 4. Specifically, the corresponding magnetic poles of the adjacent working surfaces of the probe disk 5 and the upper magnetic ring 3 and the lower magnetic ring 4 form downward and upward repulsive forces respectively. The two sets of repulsive forces and the gravity of the rigid mover together determine the equilibrium position of the rigid mover. The probe 6 is installed at the bottom of the probe disk 5, and the axis of the probe 6 coincides with the center line of the probe disk 5. The probe 6 and the probe disk 5 can be rigidly connected by means of threaded connection, clamping fixation or integrated processing. The lower end of the probe 6 extends out of the lower housing 2. The probe 6 does not contact the lower housing 2, thus avoiding friction between the probe 6 and the lower housing 2.

[0029] The rigid mover is suspended by the combined magnetic force of the upper magnetic ring 3 and the lower magnetic ring 4 and the gravity of the rigid mover. When the probe 6 is not in contact with the workpiece, the rigid mover is in the initial equilibrium position. When the probe 6 comes into contact with the workpiece, the weak contact force causes the mover to deviate from the equilibrium position and produce axial displacement and slight tilt.

[0030] The FDM2 displacement sensor 7 is fixedly mounted on the upper housing 1. The FDM2 displacement sensor 7 measures the vertical displacement of the probe disk 5, and the measured value is used to calculate the vertical displacement of the probe tip, where the probe tip refers to the measurement point of the probe. At least three FDM2 displacement sensors 7 are used, distributed along the circumference of the probe disk 5. A measurement and control unit is also included, which receives the measured values ​​from the FDM2 displacement sensors 7 and calculates the vertical displacement of the probe tip based on these values.

[0031] In one implementation, three FDM2 displacement sensors 7 are used, evenly distributed along the circumference of the probe disk 5, and vertically arranged. The formula for calculating the vertical displacement of the probe tip is: ;in, This represents the axial displacement of the rigid mover reference point. The small tilt angle of the rigid mover about the X-axis; For the small tilt angle of the rigid mover about the Y-axis; Let be the lateral coordinate of the probe tip relative to the rigid mover reference point. The coordinates of the probe tip relative to the rigid mover reference point are given.

[0032] ; ;in, These are the measurements from three FDM2 sensors; The installation radius is for the three FDM2 units.

[0033] Four-in-one magnetic support with upper and lower magnetic rings and weak force response model: The rigid mover inside the probe is subjected to the combined effects of gravity, the force of the upper magnetic ring 3, the force of the lower magnetic ring 4, and contact force. Let the mass of the mover be m, and the acceleration due to gravity be g, then the gravity of the mover is: .

[0034] Let the axial force exerted by the magnet on the rigid mover be... The axial force exerted by the lower magnet on the rigid mover is... , where z represents the axial displacement of the rigid mover relative to the reference position. Considering the different directions and magnitudes of the upper and lower magnets, they can be combined into a single axial magnetic force: In the formula, This represents the resultant magnetic force acting on the rigid mover along its axial direction. In practical design, the specific sign can be defined based on the coordinate direction and magnetization direction. In the non-contact state, the rigid mover is in its equilibrium position. Satisfying ,Right now .

[0035] When the probe comes into contact with the workpiece surface, the workpiece exerts a contact force Fc on the probe, which is transmitted to the rigid mover through the probe. The axial equilibrium relationship of the rigid mover at this time can be expressed as: Therefore, the contact force can be written as: ; Near the equilibrium position, if the displacement of the mover is small, the resultant magnetic force-displacement relationship can be expressed as follows: Neighborhood linearization: ,in, The axial equivalent stiffness of the magnetic field near the equilibrium position: , because Then the contact force within the small displacement range can be approximately expressed as: ;in: ; This relationship indicates that once the magnetic force-displacement relationship is calibrated, the contact force can be indirectly calculated from the displacement change of the rigid mover. If the magnetic force-displacement relationship within the working area is approximately linear, equivalent stiffness can be used. Perform contact force estimation; if significant nonlinearity exists, use a calibration function. Perform the calculation: .

[0036] To meet the upper limit requirement for contact force in weak force contact measurements, the maximum permissible contact force can be set to 1 mN, and a "safe displacement threshold" can be used for protection control. The safe displacement threshold of the probe tip corresponding to a 1 mN contact force is: During the actual measurement process, three FDM2 white light interferometric displacement sensors acquired the three-point displacement of the rigid mover in real time, and obtained the axial displacement and attitude parameters of the mover through rigid body pose calculation, and further calculated the probe end displacement. When the displacement calculated at the probe end satisfies: When the system determines that the contact force has reached the safety limit, it immediately executes a stop feed or retraction protection to avoid the contact force exceeding the design constraint of 1 mN.

[0037] To improve the stability and safety of the measurement process, the control system can employ a graded threshold control strategy. When the probe tip displacement is below the warning threshold, the system maintains normal measurement; when the probe tip displacement approaches the safety threshold, the system reduces the feed rate or suspends measurement; when the probe tip displacement reaches the safety threshold, the system immediately stops feeding and executes a back-off protection. This strategy transforms the problem of controlling weak contact forces into a problem of judging high-precision displacement thresholds, enabling the FDM2's nanometer-level displacement detection capability to directly serve contact force safety control.

[0038] The probe response speed is mainly determined by the rigid mover mass, the equivalent stiffness of the combined magnetic force, the system damping, and the control sampling frequency. Under small disturbance conditions, the axial motion of the mover can be equivalent to a single-degree-of-freedom system, whose natural frequency is approximately expressed as: ; By controlling the mass of the rigid mover and optimizing the magnet gap and magnet dimensions, a balance can be achieved between sensitivity to weak forces and dynamic response. The FDM2 sensor has high-frequency displacement acquisition capabilities, providing real-time feedback for minute displacement changes and contact state changes. Simultaneously, the control system executes deceleration, stopping, and retraction actions based on displacement thresholds, thereby ensuring the safety of the probe under conditions such as inclined plane following, upward retraction, and abnormal contact. The magnetic force-displacement relationship and working area design diagram are shown below. Figure 3 As shown.

[0039] See Figure 2As shown, in one embodiment, both the probe disk 5 and the probe 6 are made of ferromagnetic material; the rigid mover also includes a permanent magnet 9; the permanent magnet 9 is fixedly sleeved on the probe 6, and is located below the lower housing 2; a magnetic shield 8 is provided between the permanent magnet 9 and the lower housing 2. The permanent magnet 9 magnetizes the probe disk 5 and the probe 6, making the probe disk 5 magnetic, thus providing conditions for the probe disk 5 to levitate between the upper magnetic ring 3 and the lower magnetic ring 4. The magnetic shield 8 prevents the permanent magnet 9 from interfering with the lower magnetic ring.

[0040] The magnetic shielding component 8 includes a sleeve 81 and a retaining ring 82; the sleeve 81 is provided with a clearance hole at one end near the probe disk 5 for the probe 6 to pass through; the permanent magnet 9 is located inside the sleeve 81 and does not contact the sleeve 81; the retaining ring 82 is fixedly disposed at one end of the sleeve 81 away from the probe disk 5, and the retaining ring 82 is fixedly connected to the lower housing 2.

[0041] The lower housing 2 has a mounting hole for mounting the sleeve 81, and the sleeve 81 is located in the mounting hole. This design reduces the space occupied by the sleeve 81 and avoids making the probe 6 too long.

[0042] A measurement method for the aforementioned magnetic levitation probe, see [link / reference] Figure 4 As shown, it includes the following steps: S1. The magnetic levitation probe is vertically mounted on the Z-axis feed mechanism; the Z-axis feed mechanism can move both horizontally and vertically. S2. Control the probe tip of the probe 6 to contact the surface of the workpiece to be measured; control the Z-axis feed mechanism to move to drive the magnetic levitation probe to move, so that the probe tip moves along the surface of the workpiece to measure, while the FDM2 displacement sensor 7 acquires the vertical displacement of the probe disk 5 in real time. S3. Calculate the vertical displacement value of the probe tip based on the measurement value of the FDM2 displacement sensor 7. ; S4. Measure the vertical displacement value of the probe tip. With respect to the pre-calibrated safety threshold of the probe tip Comparison; when the vertical displacement value of the probe tip exceeds the safety threshold, i.e. The Z-axis feed mechanism is controlled to stop feeding and retract for protection.

[0043] Preferably, see Figure 5 As shown, step S4 includes: S41: The vertical displacement value of the probe tip The warning threshold at the probe tip was compared with the pre-calibrated threshold. Compare; the vertical displacement value of the probe tip Not exceeding the warning threshold At that time, that is The Z-axis feed mechanism continues to move, and the probe tip continues to measure along the surface of the workpiece. S42: Vertical displacement value of the probe tip Exceeding the warning threshold And not exceeding the safety threshold When the value is, that is Control the Z-axis feed mechanism to reduce the feed speed or pause and trigger an alarm; S43: Vertical displacement value of the probe tip Exceeding the safety threshold At that time, that is The Z-axis feed mechanism is controlled to stop feeding and retract for protection.

[0044] The magnetic levitation probe of this application can realize the measurement of weak contact force, which meets the requirements of low-damage contact measurement of soft and brittle materials, thin-walled structures and micro-nano modulated surfaces.

[0045] As one implementation method, a security threshold can be used. The corresponding contact force is set at 1 mN, and the warning threshold is... The corresponding contact force is set at 0.8 mN, when When the Z-axis feed mechanism continues to move, the probe tip continues to measure along the surface of the workpiece, i.e., normal measurement; when When the feed mechanism in the Z direction is slowed down or paused and an alarm is triggered; when When the Z-axis feed mechanism stops feeding and retracts for protection, it avoids contact force exceeding 1 mN, thereby achieving weak contact force measurement and meeting the low-damage contact measurement requirements of complex curved surfaces, microstructures and soft and brittle material surfaces in three-dimensional measurement.

[0046] In terms of displacement sensing, this application employs three FDM2 sensors positioned above a rigid mover to perform non-contact displacement measurements at three measurement points on the rigid mover. The FDM2 sensors utilize a white light / low-coherence interferometry principle, offering non-contact, force-free operation, high sampling frequency, and nanometer-level displacement resolution. Their function is not direct force measurement, but rather real-time acquisition of the three-point displacement information of the mover. Through three-point displacement calculation, the central axial displacement of the mover and its minute tilt angles in two directions can be obtained. Combined with the geometric position of the probe tip relative to the mover's coordinate system, the actual displacement of the probe tip is calculated. This forms a measurement chain of "FDM2 three-point displacement measurement—motor pose calculation—probe tip displacement inverse calculation—contact force indirect inversion."

[0047] FDM2 White Light Interferometric Displacement Sensor: Principle and Selection Criteria The FDM2 white-light interferometric displacement sensor is the core sensing unit for this probe to detect weak forces. It's important to clarify that the FDM2 itself is not a force sensor, but rather a non-contact, high-precision displacement sensor. Its output is the distance or displacement change between the probe and the measured reflective surface. This probe utilizes three FDM2 sensors to perform three-point displacement measurements on the probe-platform rigid mover, and then indirectly inverts the contact force through subsequent pose calculations and magnetic levitation stiffness calibration.

[0048] The FDM2 employs a white light / low-coherence interferometry principle. Its basic idea is to utilize a broadband optical signal generated by a low-coherence light source, guided by an optical fiber probe to the surface under test to form the measurement light, while a reference light is generated simultaneously from the probe end face or internal reference structure. The optical path difference information carried by the measurement light and the reference light forms a low-coherence interference signal at the receiving end. By analyzing the position of the interference envelope peak and the phase information of the interference fringes, the distance change between the probe and the surface under test can be obtained. Unlike traditional mechanical scanning measurements, the low-coherence interferometry method can achieve non-contact absolute distance measurement through interference signal analysis, featuring small probe size, flexible structure, and suitability for confined spaces. The FDM2 white light interferometry measurement method is as follows: Figure 6 As shown.

[0049] In signal processing, FDM2-type low-coherence interferometry typically employs a two-stage processing strategy of "coarse positioning + fine positioning." First, the contrast peak of the interference envelope is used to determine a coarse distance value. Then, the distance result is finely corrected by combining the phase information of the interference fringes, thereby achieving nanometer-level displacement measurement. Multi-wavelength or low-coherence designs can shorten the effective coherence length, improve the reliability of central envelope peak identification, and reduce the risk of fringe order misjudgment. This measurement mechanism provides the fundamental basis for FDM2 to achieve high-precision detection of minute displacements within the probe.

[0050] From an engineering perspective, the FDM2 sensor features non-contact operation, no force measurement, high sampling frequency, and high resolution. According to existing data, the FDM2 sensor operates on the principle of white light interferometry, achieving a measurement resolution of up to 0.05 nm, a sampling frequency of up to 40 kHz, and a repeatability error on the order of 2–5 nm. Furthermore, its measurement process is non-contact and force-free. These characteristics enable the FDM2 to acquire minute displacement changes of the magnetically levitated mover in real time without interfering with its mechanical state.

[0051] Furthermore, the FDM2 employs a miniature fiber optic probe, the diameter of which can be selected according to the specific model and installation space, adapting to the compact internal space of the probe head. The fiber optic probe can perform axial or angular measurements, facilitating a three-point arrangement below the probe head. Three FDM2 probes, through a well-designed installation radius and working distance, perform non-contact measurements at three points on the moving part, enabling multi-point displacement sensing within a limited structural space.

[0052] The role of FDM2 in this probe can be summarized in three aspects: First, as a non-contact displacement sensor, it acquires the three-point micro-displacement of the rigid mover in real time; second, it provides input for mover pose calculation through three-point measurement; third, combined with the magnetic levitation stiffness model and safe displacement threshold control, it realizes indirect back-calculation of contact force and overload protection. Therefore, FDM2 is a key sensing unit connecting the magnetic levitation weak force response structure with the probe's measurement and control system.

[0053] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0054] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A magnetically levitated probe, characterized in that, Includes housing, upper magnetic ring, lower magnetic ring, rigid mover, and FDM2 displacement sensor; The housing includes an upper housing and a lower housing; the upper magnetic ring is fixedly installed on the upper housing and the lower magnetic ring is fixedly installed on the lower housing; both the upper magnetic ring and the lower magnetic ring are located inside the housing; The rigid mover includes a probe disk and a probe; the probe disk is located between the upper magnetic ring and the lower magnetic ring; the probe disk is magnetic, and the probe disk has a repulsive force with both the upper and lower magnetic rings to stably suspend the probe disk between the upper and lower magnetic rings; the probe is installed at the bottom of the probe disk, and the lower end of the probe extends out of the lower housing; the probe does not contact the lower housing. The FDM2 displacement sensor is fixedly installed on the upper housing. The FDM2 displacement sensor measures the vertical displacement of the probe disk, and the measured value is used to calculate the vertical displacement of the probe tip. There are at least three FDM2 displacement sensors, which are distributed along the circumferential direction of the probe disk.

2. The magnetic levitation probe according to claim 1, characterized in that, It also includes a measurement and control unit, which is used to receive the measurement value of the FDM2 displacement sensor and calculate the vertical displacement of the probe tip based on the measurement value of the FDM2 displacement sensor.

3. The magnetic levitation probe according to claim 2, characterized in that, There are three FDM2 displacement sensors, which are evenly distributed along the circumferential direction of the probe disk and are vertically arranged.

4. The magnetic levitation probe according to claim 3, characterized in that, The formula for calculating the vertical displacement of the probe tip is: ;in, This represents the axial displacement of the rigid mover reference point. The small tilt angle of the rigid mover about the X-axis; For the small tilt angle of the rigid mover about the Y-axis; Let be the lateral coordinate of the probe tip relative to the rigid mover reference point. The coordinates of the probe tip relative to the rigid mover reference point are given.

5. The magnetic levitation probe according to claim 4, characterized in that, The ; ;in, These are the measurements from three FDM2 sensors; The installation radius for the three FDM2s.

6. The magnetic levitation probe according to claim 1, characterized in that, The probe disc and the probe are both made of ferromagnetic material; the rigid mover also includes a permanent magnet 9; the permanent magnet 9 is fixedly sleeved on the probe and is located below the lower housing; a magnetic shielding component 8 is provided between the permanent magnet 9 and the lower housing.

7. The magnetic levitation probe according to claim 5, characterized in that, The magnetic shielding component 8 includes a sleeve 81 and a retaining ring 82; the sleeve 81 is provided with a clearance hole at one end near the probe disk for the probe to pass through; the permanent magnet 9 is located inside the sleeve 81 and does not contact the sleeve 81; the retaining ring 82 is fixedly disposed at one end of the sleeve 81 away from the probe disk, and the retaining ring 82 is fixedly connected to the lower housing.

8. The magnetic levitation probe according to claim 4, characterized in that, The lower housing has a mounting hole for installing the sleeve 81, and the sleeve 81 is located in the mounting hole.

9. A measurement method for the magnetically levitated probe according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Vertically install the magnetic levitation probe on the Z-axis feed mechanism; S2. Control the probe tip to contact the surface of the workpiece to be measured; control the Z-axis feed mechanism to move to drive the magnetic levitation probe to move, so that the probe tip moves along the surface of the workpiece to measure, while the FDM2 displacement sensor acquires the vertical displacement of the probe disk in real time. S3. Calculate the vertical displacement value of the probe tip based on the measurement value of the FDM2 displacement sensor; S4. Compare the vertical displacement value of the probe tip with the pre-calibrated safety threshold of the probe tip; when the vertical displacement value of the probe tip exceeds the safety threshold, control the Z-axis feed mechanism to stop feeding and retract for protection.

10. The measurement method according to claim 9, characterized in that, Step S4 includes: S41: Compare the vertical displacement value of the probe tip with the pre-calibrated warning threshold of the probe tip; when the vertical displacement value of the probe tip does not exceed the warning threshold, control the Z-axis feed mechanism to continue moving, and the probe tip continues to measure along the surface of the workpiece. S42: When the vertical displacement value of the probe tip exceeds the warning threshold but does not exceed the safety threshold, control the Z-axis feed mechanism to reduce the feed speed or pause and alarm; S43: When the vertical displacement value of the probe tip exceeds the safety threshold, control the Z-axis feed mechanism to stop feeding and retract for protection.

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