A method for recognizing the detection direction of a microstructure three-dimensional measurement probe and compensating for deformation

Abstract

The application discloses a kind of detection direction identification and deformation compensation methods of microstructure three-dimensional measurement probe, the probe includes base, suspension mechanism and detection component;Base is opened with empty slot, and detection component and detection component are installed in empty slot;Suspension mechanism is installed at the notch of empty slot;Empty slot is provided with ball socket.Detection component includes contact ball, sampling rod, electrode ball and spherical electrode plate group;Spherical electrode plate group includes five spherical electrode plates;Five spherical electrode plates are fixed on the inner wall of ball socket;The side of each spherical electrode plate towards the ball center of ball socket is concave spherical crown face;The ball center of spherical crown face on spherical electrode plate is coincident with the ball center of ball socket.Electrode ball is installed between five spherical electrode plates.The application effectively improves the efficiency of measurement by the principle of capacitance sensor formed by the gap change between spherical electrode plate and electrode ball, measurement operation is convenient, while guaranteeing the measurement accuracy, reduce measurement cost.

Description

Technical Field

[0001] This invention belongs to the field of precision measuring instrument technology, specifically relating to a method for identifying the detection direction and compensating for deformation of a microstructure three-dimensional measuring probe. Background Technology

[0002] As one of the current trends in science and technology and industrial development, high precision and miniaturization are driving the increasing market demand for micro-sized components. Consequently, the measurement requirements for micro-sized components, such as precision, are also gradually increasing.

[0003] Taking micro-hole measurement as an example, micro-holes are a common geometric feature in micro-components, and their accuracy affects the performance of the component. Various methods exist for measuring conventional hole geometry (such as aperture). However, due to the influence of spatial dimensions and contact forces, many methods are unsuitable for micro-hole measurement. In the field of micro-hole measurement, researchers have studied measurement methods such as laser methods, vibration methods, and strain gauge methods. However, these methods require complex systems, complex data processing, and high requirements for installation space and working environment in practical applications, resulting in significant costs and limitations. Compared to existing methods, measurement systems equipped with tactile microprobes are more suitable for three-dimensional measurement of microstructures. The main limiting factors related to microprobes include tip size, measurement force, and stiffness. The tip size determines the minimum measurable internal size of the microstructure; the measurement force should be as small as possible to avoid deformation of the microstructure; and the stiffness should be as large as possible to avoid measurement errors caused by probe deformation. Compared to rigid probes, elastic probes exhibit better performance in terms of tip size, measurement force, and stiffness. In reality, ideal rigid bodies do not exist. Whether it's a rigid probe or an elastic probe, deformation is inevitable upon contact. In current measurement techniques, probe deformation compensation methods are one of the existing problems. Summary of the Invention

[0004] The purpose of this invention is to provide a method for identifying the detection direction and compensating for deformation of a three-dimensional measurement probe for microstructures.

[0005] In a first aspect, the present invention provides a microstructure three-dimensional measurement probe, which includes a base, a suspension mechanism and a detection component; a slot is provided on the base, and the detection component is installed in the slot; the suspension mechanism is installed at the opening of the slot; a ball socket is provided in the slot.

[0006] The detection assembly includes a contact ball, a sampling rod, an electrode ball, and a spherical electrode plate assembly. The spherical electrode plate assembly includes five spherical electrode plates, all of which are fixed to the inner wall of the spherical cavity. A spatial rectangular coordinate system is established with the center of the spherical cavity as the origin, and the z-axis of the spatial rectangular coordinate system is perpendicular to the plane where the opening of the spherical cavity is located. The five spherical electrode plates are designated as the first spherical electrode plate, the second spherical electrode plate, the third spherical electrode plate, the fourth spherical electrode plate, and the fifth spherical electrode plate. The central axes of the first and second spherical electrode plates coincide with the x-axis of the spatial rectangular coordinate system. The central axes of the third and fourth spherical electrode plates coincide with the y-axis of the spatial rectangular coordinate system. The central axis of the fifth spherical electrode plate coincides with the z-axis of the spatial rectangular coordinate system. The side of each spherical electrode plate facing the center of the spherical cavity is a concave spherical cap. The center of the spherical cap on all spherical electrode plates coincides with the center of the spherical cavity.

[0007] The electrode ball is installed between five spherical electrode plates and has a zero-position gap d0 between it and the five spherical electrode plates; the five spherical electrode plates and the electrode ball respectively form five spherical capacitors; the capacitance values ​​of the five spherical capacitors are C1 to C5 respectively.

[0008] The inner end of the sampling rod is fixed to the electrode ball; the outer end of the sampling rod is provided with a contact ball. The sampling rod is connected to the frame through a suspension mechanism; under the constraint of the suspension mechanism, when the contact ball is moved by an external force, it drives the sampling rod to perform one or more of the following movements: moving along the z-axis, rotating around the x-axis, and rotating around the y-axis.

[0009] Preferably, the suspension mechanism includes an annular support plate, elastic suspensions, and a connecting ring; the annular support plate is fixed to the base; the connecting ring is located at the center of the annular support plate; multiple elastic suspensions are disposed between the annular support plate and the connecting ring. One end of the elastic suspension is fixed to the annular support plate; the other end of the elastic suspension is fixed to the connecting ring; the sampling rod passes through the connecting ring and is fixed to the connecting ring.

[0010] Preferably, the elastic suspension includes a first elastic segment and a second elastic segment; one end of the first elastic segment is connected to an annular support plate, and the other end of the first elastic segment is connected to one end of the second elastic segment; the other end of the second elastic segment is connected to a connecting ring; both the first and second elastic segments are straight; the included angle between the first and second elastic segments is an acute angle; the width of the second elastic segment is greater than the width of the first elastic segment; both the first and second elastic segments are straight.

[0011] Preferably, the zero-position gap d0 between the electrode ball and the five spherical electrode plates is ≤0.2mm.

[0012] Preferably, the spherical electrode plate and electrode ball are made of copper.

[0013] Preferably, the sampling rod is made of tungsten carbide, and the contact ball is made of ruby.

[0014] Preferably, the elastic suspension is made of beryllium bronze.

[0015] Preferably, the base is made of PVC material or structural steel with an insulating coating on the surface.

[0016] Preferably, in the initial state, the center of the electrode ball coincides with the center of the fovea; the center of the electrode ball is located on the central axis of the sampling rod.

[0017] Secondly, the method for identifying the detection direction and compensating for deformation using the aforementioned microstructure three-dimensional measurement probe includes the following steps:

[0018] Includes the following steps:

[0019] Step 1: Detect the capacitance values ​​C1 to C5 between the five spherical electrode plates and the electrode spheres.

[0020] Step 2: Construct the dimensionless offset of the solution electrode sphere The system of equations is as follows:

[0021]

[0022] Wherein, θ1 is half of the cone angle of the spherical cone corresponding to the spherical cap surface on the first spherical electrode plate (1-1); Let x be the angle between the line connecting the point closest to the x-axis on the first spherical electrode plate (1-1) and the origin, and the x-axis. R0 is the angle between the line connecting the point furthest from the x-axis on the first spherical electrode plate (1-1) and the origin, and the x-axis; R0 is the radius of the concave spherical cap surface of each spherical electrode plate. This is the initial capacitance value between the fifth spherical electrode plate (1-5) and the electrode ball.

[0023] , , The expressions are as follows:

[0024]

[0025] in, .

[0026] Based on the dimensionless offset of the electrode ball Calculate the displacement of the electrode ball .in, , , .

[0027] Step 3: Calculate the displacement of the ball at contact in the X, Y, and Z axes. , , :

[0028]

[0029]

[0030]

[0031] Where k is the lever amplification factor, which is equal to the ratio of the distance from the center of the electrode ball to the suspension mechanism to the distance from the center of the contact ball to the suspension mechanism; , , This is the offset of the electrode ball. , , ) represents the triaxial elastic offset component of the ball contact.

[0032] Preferably, the triaxial elastic offset component of the ball contact ( , , The expression for ) is as follows:

[0033]

[0034] Where u is the total elastic offset at contact with the ball. γ is the angle between the sampling rod axis and the Z-axis; γ is the angle between the projection of the sampling rod onto the XOY plane and the X-axis; l is the length of the contact section of the sampling rod.

[0035] included angle The expression is as follows:

[0036]

[0037] The expression for the included angle γ is as follows:

[0038]

[0039] The expression for the total elastic offset u at ball contact is as follows:

[0040]

[0041] in, t is the tangential component of the gravity of the electrode ball along the sampling rod; t is the shear elastic coefficient of the contact section of the sampling rod.

[0042] The beneficial effects of this invention are:

[0043] 1. This invention utilizes the principle of a capacitive sensor formed by the change in the gap between the spherical electrode plate and the electrode ball, which effectively improves measurement efficiency, facilitates measurement operation, and reduces measurement costs while ensuring measurement accuracy.

[0044] 2. By sensing three-dimensional displacement, this invention can compensate for the force deformation of the probe during the measurement process, thereby improving measurement accuracy.

[0045] 3. This invention improves detection sensitivity by setting up several spherical electrode plates, and the multiple spherical electrode plates form a differential capacitor group. The capacitance change has a good linearity and can quickly reflect the contact status of the probe touching the ball.

[0046] 4. This invention sets up a contact probe and a transmission probe rod to form a structure of unequal length, which amplifies the displacement at the lower end. At the same time, it uses the capacitance change of the electrode ball on the spherical electrode array to reflect the motion change, thereby improving the measurement sensitivity.

[0047] 5. By setting up an elastic suspension, this invention improves the sensitivity of the measurement while avoiding excessive contact of the probe during the measurement process, thus overcoming the problem of large measurement errors caused by excessive measurement force. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0049] Figure 2 This is a schematic diagram of the detection component in this invention.

[0050] Figure 3 This is a schematic diagram of the suspension mechanism in this invention.

[0051] Figure 4 For the present invention Figure 1 A sectional view of section AA in the middle.

[0052] Figure 5 This is a schematic diagram of the mathematical model of the gap between the electrode ball and the socket in this invention.

[0053] Figure 6 This is a schematic diagram of the force applied to the sampling rod of the present invention.

[0054] Among them, 1. Spherical electrode plate group; 1-1. First spherical electrode plate; 1-2. Second spherical electrode plate; 1-3. Third spherical electrode plate; 1-4. Fourth spherical electrode plate; 1-5. Fifth spherical electrode plate; 2. Electrode ball; 3. Sampling rod; 3-1. Transmission section; 3-2. Contact section; 4. Suspension mechanism; 5. Base; 6. Contact ball. Detailed Implementation

[0055] The present invention will be further described below with reference to the accompanying drawings.

[0056] like Figure 1 and 2 As shown, a microstructure three-dimensional measurement probe includes a base 5, a suspension mechanism 4, and detection components. The base 5 has a slot, and the detection components are all installed within the slot. The suspension mechanism 4 is installed at the opening of the slot. A ball-and-socket joint is formed on the bottom surface of the slot.

[0057] The detection assembly includes a contact ball 6, a sampling rod 3, an electrode ball 2, and a spherical electrode plate assembly 1. The spherical electrode plate assembly 1 comprises five spherical electrode plates, all fixed to the inner wall of the spherical cavity. A spatial rectangular coordinate system is established with the center of the spherical cavity as the origin, and the z-axis of the spatial rectangular coordinate system is perpendicular to the plane containing the opening of the spherical cavity. The five spherical electrode plates are designated as the first spherical electrode plate 1-1, the second spherical electrode plate 1-2, the third spherical electrode plate 1-3, the fourth spherical electrode plate 1-4, and the fifth spherical electrode plate 1-5. The axes of the first spherical electrode plate 1-1 and the second spherical electrode plate 1-2 coincide with the x-axis of the spatial rectangular coordinate system. The axes of the third spherical electrode plate 1-3 and the fourth spherical electrode plate 1-4 coincide with the y-axis of the spatial rectangular coordinate system. The axis of the fifth spherical electrode plate 1-5 coincides with the z-axis of the spatial rectangular coordinate system.

[0058] The side of each spherical electrode plate facing the center of the spherical socket is a concave spherical cap. All spherical electrode plates have the same shape. The center of the spherical cap on all spherical electrode plates coincides with the center of the spherical socket.

[0059] like Figure 4 As shown, electrode sphere 2 is installed between five spherical electrode plates, and a zero-position gap d0 is provided between electrode sphere 2 and each of the five spherical electrode plates; d0≤0.2mm. The center of electrode sphere 2 coincides with the center of the spherical socket. The five spherical electrode plates and electrode sphere 2 respectively form five spherical capacitors; the capacitance values ​​of the five spherical capacitors are denoted as C1~C5 respectively.

[0060] The inner end of the sampling rod 3 is fixed to the electrode ball 2. The center of the electrode ball is located on the central axis of the sampling rod 3. The sampling rod 3 is divided into a transmission section 3-1 between the suspension mechanism 4 and the electrode ball 2, and a contact section 3-2; a contact ball 6 is provided at the outer end of the contact section 5. The contact ball 6 can be a sphere that is independently fixed to the outer end of the contact section 5, or it can be a spherical surface integrally formed on the outer end of the contact section 5. The diameter of the contact ball 6 is slightly larger than the diameter of the sampling rod 3. The diameter range of the contact ball 6 is 0.3~0.5mm. The contact ball 6 is used to contact the object being tested and to transmit the force generated during contact to the sampling rod 3.

[0061] like Figure 3As shown, the suspension mechanism 4 employs a three-hinged suspension beam, comprising an annular support plate, elastic suspensions, and a connecting ring. The annular support plate is fixed to the base 5. The connecting ring is located at the center of the annular support plate. The outer ends of the three elastic suspensions are fixed to the inner edges of the annular support plate. The inner ends of the elastic suspensions are fixed to the outer edges of the connecting ring. The sampling rod 3 passes through the connecting ring and is fixed to it. To achieve an elastic suspension that rotates around the x and y axes and translates along the z axis, constraints need to be placed on the degrees of freedom of the elastic suspension along the x and y axes and around the z axis.

[0062] like Figure 3 As shown, the elastic suspension includes a first elastic segment and a second elastic segment. One end of the first elastic segment is connected to an annular support plate, and the other end of the first elastic segment is connected to one end of the second elastic segment; the other end of the second elastic segment is connected to a connecting ring. Both the first and second elastic segments are straight. The angle between the first and second elastic segments is an acute angle. The width of the second elastic segment is greater than the width of the first elastic segment; both the first and second elastic segments are straight beams.

[0063] Because the three elastic suspensions tend to keep the connecting ring at the center of the inner circumference of the annular support plate, the external force required for the sampling rod 3 to displace along the x and y axes is much greater than the contact force required for the contact ball 6 to rotate around the x and y axes when in contact with the outside. Therefore, the suspension mechanism 4 constrains the sampling rod to move only along the z axis and rotate around the x and y axes during the detection process; and drives the sampling rod 3 to reset after the detection is completed.

[0064] When the contact ball 6 at the outer end of the sampling rod 3 comes into contact with the outside, it causes the elastic suspension to deform, resulting in a sway between the sampling rod 3 and the electrode ball 2. During this eccentric movement, the gap between the electrode ball 2 and each spherical electrode plate changes, thus altering the capacitance values ​​C1 to C5 of the five spherical capacitors. The offset of the electrode ball 2 is calculated by measuring the change in capacitance values, thereby detecting the offset of the electrode ball 2 relative to its initial position. Furthermore, by setting a threshold for the capacitance change, accidental or excessive contact of the sampling rod 3 can be effectively prevented.

[0065] Due to the characteristics of the suspension mechanism 4, the sampling rod 3 only moves along the z-axis and rotates around the x and y axes, while the movement or rotation of the sampling rod 3 in other degrees of freedom can be ignored. Furthermore, since the rotation amplitude of the sampling rod 3 is extremely small (less than 0.17°), the rotation of the contact ball and electrode ball around the x-axis can be equivalent to the reverse movement along the y-axis; the rotation of the contact ball and electrode ball around the y-axis can be equivalent to the movement along the x-axis.

[0066] Therefore, the z-axis displacements of the contact ball and the electrode ball are equal; the x-axis displacements of the contact ball and the electrode ball are opposite in direction and are multiples of each other; the y-axis displacements of the contact ball and the electrode ball are opposite in direction and are multiples of each other; the specific multiples are related to the lever amplification factor of sampling rod 3.

[0067] The present invention provides a non-essential preferred feature: the spherical electrode plate and the electrode ball are made of materials with good electrical conductivity, such as copper or silver.

[0068] The present invention provides a non-essential preferred feature: the sampling rod 3 is made of a material with high stiffness, such as tungsten carbide.

[0069] The present invention provides a non-essential preferred feature: the contact ball is made of a high-rigidity material, such as ruby ​​or silicon dioxide.

[0070] The present invention provides a non-essential preferred feature: the elastic suspension in the suspension mechanism 4 is made of a material with high strength and low coefficient of thermal expansion, such as beryllium bronze.

[0071] The present invention provides a non-essential preferred feature: the base 5 is made of a material that is easy to process and does not conduct electricity, such as PVC material, or structural steel with an insulating coating on the surface.

[0072] The principle of this microstructure three-dimensional measurement probe for detecting minute displacements is as follows:

[0073] like Figure 1 As shown, the original capacitance value (i.e., the initial value) of capacitance value C5 is taken as capacitance value C0. Eccentricity along the x, y, and z axes. , The theoretical calculation formula is expressed as:

[0074] (1)

[0075] In equation (1), f X (·), f Y (·), f Z (·) represent the functions of the displacement of electrode ball 2 along the X, Y, and Z axes and the capacitance value, respectively. Their values ​​are related to the structural parameters of the capacitor and the amplification factor of the measurement and processing circuit. Let ΔC Ct Let t be the difference obtained for each capacitor group, where t = x, y, z.

[0076] but:

[0077]

[0078] Formula (1) simplifies to:

[0079]

[0080] like Figure 5 As shown, the origin of the spatial rectangular coordinate system is set as point O, and the unit vectors of the X, Y, and Z axes in the coordinate system OXYZ are denoted as follows: The deflection angle of electrode sphere 2 relative to the Z-axis is θ, 0 ≤ θ ≤ π; the azimuth angle of electrode sphere 2 relative to the X-axis is φ, 0 ≤ φ ≤ 2π. The unit vector of the outward normal OP of any point P on the surface of electrode sphere 2 relative to the coordinate system OXYZ is:

[0081] .

[0082] Considering the opposing surfaces of the spherical electrode plate and electrode sphere 2 as ideal spheres, let R0 be the radius of the concave spherical cap of the spherical electrode plate, r be the radius of electrode sphere 2, and δ be the linear displacement of the center O' of electrode sphere 2 relative to the center O of the spherical socket. Therefore, the eccentric linear displacement vector of electrode sphere 2 is expressed as:

[0083]

[0084] In the formula, δ X δ Y δ Z They are respectively Projection onto the X, Y, and Z axes.

[0085] Connect the center O' of electrode sphere 2 to any point P, and let the extension of this connection intersect the concave spherical cap surface of the spherical electrode plate at point Q. The distance from Q to P is the gap d at point P. When the sphere head is not eccentric, the initial gap d0 is:

[0086]

[0087] like Figure 5 As shown, when electrode ball 2 has a three-degree-of-freedom eccentricity relative to the ball-and-socket, at δ In the case of R0, From the vector relationship, we can obtain:

[0088]

[0089] Therefore, the gap d at point P after the electrode ball 2 is offset is as shown in equation (3).

[0090]

[0091] To simplify the calculation, we assume that the spherical capacitance dC corresponding to the infinitesimal area dA of the spherical electrode plate is a parallel-plate capacitor with equal spacing, and we neglect the edge effect of the parallel-plate capacitor. Therefore, the capacitance value of each pair of spherical capacitors can be expressed using the area integral formula:

[0092]

[0093] In the formula, ε represents the dielectric constant of the material between the spherical electrode plate and electrode ball 2, and S eLet e ​​represent the effective area of ​​the spherical electrode plate and electrode ball 2 in the spherical capacitor, where e = 1, 2, 3, 4, 5.

[0094] For ease of representation, dimensionless quantities are introduced. Equation (3) can be rewritten in dimensionless form:

[0095]

[0096] make The eccentricity of electrode ball 2 is relatively small, with its maximum eccentricity being on the same order of magnitude as the zero-position gap, resulting in λ < 1. According to the Taylor series expansion:

[0097]

[0098] After rearranging formulas (5) and (6), and substituting them into formula (4), the capacitance value of the spherical capacitor formed between each spherical electrode plate and electrode ball 2 is obtained. The expression simplifies to:

[0099]

[0100] In the formula, .

[0101] With ΔC cx Taking calculation as an example, the calculation process will be explained in detail. Since the central angles of the first spherical electrode plate 1-1 and the second spherical electrode plate 1-2 range from 0 to θ1, where θ1 is half the cone angle of the spherical cone corresponding to the spherical cap surface on the spherical electrode plate; Let x be the angle between the line connecting the point closest to the x-axis on the first spherical electrode plate and the origin, and the x-axis. Let be the angle between the line connecting the point furthest from the x-axis on the first spherical electrode plate and the origin, and the x-axis; C1: φ1≤φ≤φ2, 0≤θ≤θ1; C2: π-φ1≤φ≤π+φ2, 0≤θ≤θ1. Therefore, according to formula (7), we can obtain:

[0102]

[0103]

[0104] To simplify the calculation, equations (8) and (9) can be calculated up to the 5th power, ignoring higher-order terms above the 5th power, resulting in:

[0105]

[0106]

[0107] in, The relationship between the first spherical electrode plate 1-1 and the electrode ball 2 Coupled polynomials; The relationship between the second spherical electrode plate 1-2 and the electrode ball 2 Coupled polynomials.

[0108] Based on equations (10) and (11), the differential capacitance value ΔC can be obtained after simplification. cx for:

[0109]

[0110] in, The ratio will be as follows:

[0111]

[0112] Since the spherical electrode plates have the same essential structure, the only difference being the range of their central angles, therefore The calculation process is basically the same. Based on the above calculation process, the change in the differential capacitance value can be obtained. Includes the following steps:

[0113] Step 1: Detect the capacitance values ​​C1 to C5 between the five spherical electrode plates and the electrode spheres.

[0114] Step 2: Construct the dimensionless offset of the solution electrode sphere The system of equations is as follows:

[0115]

[0116] Wherein, θ1 is half of the cone angle of the spherical cone corresponding to the spherical cap surface on the first spherical electrode plate (1-1); Let x be the angle between the line connecting the point closest to the x-axis on the first spherical electrode plate (1-1) and the origin, and the x-axis. R0 is the angle between the line connecting the point furthest from the x-axis on the first spherical electrode plate (1-1) and the origin, and the x-axis; R0 is the radius of the concave spherical cap surface of each spherical electrode plate. This is the initial capacitance value between the fifth spherical electrode plate (1-5) and the electrode ball.

[0117] , , The expressions are as follows:

[0118]

[0119] in, .

[0120] Based on the dimensionless offset of the electrode ball Calculate the displacement of the electrode ball .in, , , .

[0121] Step 3: Calculate the displacement of the ball at contact in the X, Y, and Z axes. , , :

[0122]

[0123]

[0124]

[0125] Where k is the lever amplification factor, which is equal to the ratio of the distance from the center of the electrode ball to the suspension mechanism to the distance from the center of the contact ball to the suspension mechanism; , , This is the offset of the electrode ball. , , ) represents the triaxial elastic offset component of the ball contact.

[0126] The triaxial elastic offset component of the ball contact ( , , The expression for ) is as follows:

[0127]

[0128] Where u is the total elastic offset at contact with the ball. γ is the angle between the sampling rod axis and the Z-axis; γ is the angle between the projection of the sampling rod onto the XOY plane and the X-axis; l is the length of the contact section of the sampling rod.

[0129] included angle The expression is as follows:

[0130]

[0131] The expression for the included angle γ is as follows:

[0132]

[0133] The expression for the total elastic offset u at ball contact is as follows:

[0134]

[0135] in, t is the tangential component of the gravity of the electrode ball along the sampling rod; t is the shear elastic coefficient of the contact section of the sampling rod.

[0136] capacitance difference , The expression is as follows:

[0137]

[0138]

[0139]

[0140]

[0141] According to equations (12), (13), and (14), the relationship between the eccentric displacement and the differential capacitance value can be established. By compensating for the eccentric displacement at the coordinate contact point (X0, Y0, Z0), accurate coordinate acquisition can be obtained. In actual measurement, the spherical electrode plates are all connected to a dedicated signal processing circuit. After acquisition, the data is transmitted to a computer for processing to obtain dynamic coordinate data, thus realizing real-time contact measurement.

[0142] In actual measurements, the sampling rod 3 undergoes a certain amount of elastic deformation during contact with the object. This invention, however, obtains the offset of the electrode ball 2 from its initial position. , , Therefore, the contact force can be obtained by combining the physical properties of the suspension mechanism 4 and the sampling rod 3. The direction and magnitude of the sample rod are used to determine its elastic deformation and compensate for the input. , , This allows us to obtain the actual displacement data.

[0143] Depend on Figure 6 It can be seen that when electrode ball 2 is eccentric, the eccentricity angle with the Z-axis is... At that time, its own gravity G can be decomposed into two orthogonal forces F1 and F2. F1 is perpendicular to the sampling rod and has a magnitude of... F2 is axially downward along the sampling rod, and its size is... The suspension mechanism 4 can provide an F3 of equal magnitude and opposite direction to F2. Therefore, the force F4 acting on the contact ball 6 along the tangential direction of the sampling rod, capable of causing elastic bending deformation of the sampling rod, can be calculated. Because the sampling rod material is extremely hard, its axial deformation is negligible, so there is no need to consider its axial elastic deformation.

[0144] Therefore, elastic offset Where t is the shear elastic coefficient of the contact section of sampling rod 3.

[0145]

[0146]

[0147]

[0148]

[0149]

[0150]

[0151] γ is the angle between the sampling rod axis and the Z-axis; γ is the angle between the projection of the sampling rod onto the XOY plane and the X-axis; l is the length of the contact section of the sampling rod. , , Let u be the triaxial component of the elastic offset.

[0152] Therefore, the displacement of ball 6 in the X, Y, and Z axes is updated. , , :

[0153]

[0154]

[0155]

[0156] Where k is the lever amplification factor, which is the ratio of the length of the transmission section 3 of the sampling rod 3 to the length of the contact section 5.

[0157] Micrometer-level displacement can be detected using the contact ball 6.

[0158] In some embodiments, the detection accuracy requirement is low. , , () can be set to 0 to simplify calculations.

Claims

1. A microstructure three-dimensional measurement probe, comprising a base (5), a suspension mechanism (4), and a detection component; a slot is provided on the base (5), and the detection component is installed in the slot; the suspension mechanism (4) is installed at the opening of the slot; a ball socket is provided in the slot; The detection assembly includes a contact ball (6), a sampling rod (3), an electrode ball (2), and a spherical electrode plate group (1); the spherical electrode plate group (1) includes five spherical electrode plates; all five spherical electrode plates are fixed on the inner wall of the spherical cavity; a spatial rectangular coordinate system is set with the center of the spherical cavity as the origin, and the z-axis of the spatial rectangular coordinate system is perpendicular to the plane where the opening of the spherical cavity is located; the five spherical electrode plates are respectively the first spherical electrode plate (1-1), the second spherical electrode plate (1-2), the third spherical electrode plate (1-3), the fourth spherical electrode plate (1-4), and the fifth spherical electrode plate (1-5). Five spherical electrode plates (1-5); the central axes of the first spherical electrode plate (1-1) and the second spherical electrode plate (1-2) coincide with the x-axis of the spatial rectangular coordinate system; the central axes of the third spherical electrode plate (1-3) and the fourth spherical electrode plate (1-4) coincide with the y-axis of the spatial rectangular coordinate system; the central axis of the fifth spherical electrode plate (1-5) coincides with the z-axis of the spatial rectangular coordinate system; the side of each spherical electrode plate facing the center of the spherical cavity is a concave spherical cap surface; the center of the spherical cap surface on all spherical electrode plates coincides with the center of the spherical cavity. The electrode ball (2) is installed between five spherical electrode plates and has a zero gap d0 between it and the five spherical electrode plates; the five spherical electrode plates and the electrode ball (2) respectively form five spherical capacitors; the capacitance values ​​of the five spherical capacitors are C1 to C5 respectively; The inner end of the sampling rod (3) is fixed to the electrode ball (2); the outer end of the sampling rod (3) is provided with a contact ball (6); the sampling rod (3) is connected to the frame through a suspension mechanism (4); under the constraint of the suspension mechanism (4), when the contact ball (6) is moved by an external force, it drives the sampling rod (3) to perform one or more of the following movements: moving along the z-axis, rotating around the x-axis, and rotating around the y-axis. The sampling rod (3) is divided into a transmission section (3-1) between the suspension mechanism (4) and the electrode ball (2), and a contact section (3-2); the suspension mechanism (4) includes an annular support plate, an elastic suspension and a connecting ring; the annular support plate is fixed on the base (5); the connecting ring is located at the center of the annular support plate; multiple elastic suspensions are arranged between the annular support plate and the connecting ring; one end of the elastic suspension is fixed to the annular support plate; the other end of the elastic suspension is fixed to the connecting ring; the sampling rod (3) passes through the connecting ring and is fixed to the connecting ring; The elastic suspension includes a first elastic segment and a second elastic segment; one end of the first elastic segment is connected to an annular support plate, and the other end of the first elastic segment is connected to one end of the second elastic segment; the other end of the second elastic segment is connected to a connecting ring; both the first elastic segment and the second elastic segment are straight; the included angle between the first elastic segment and the second elastic segment is an acute angle; the width of the second elastic segment is greater than the width of the first elastic segment.

2. The microstructure three-dimensional measurement probe according to claim 1, characterized in that: The zero-position gap d0 between the electrode ball (2) and the five spherical electrode plates is ≤0.2mm.

3. The microstructure three-dimensional measurement probe according to claim 1, characterized in that: The spherical electrode plate and electrode ball (2) are made of copper.

4. The microstructure three-dimensional measurement probe according to claim 1, characterized in that: The sampling rod (3) is made of tungsten carbide; the contact ball (6) is made of ruby.

5. A microstructure three-dimensional measurement probe according to claim 1, characterized in that: The elastic suspension is made of beryllium bronze; the base (5) is made of PVC material or structural steel with an insulating coating on the surface.

6. A microstructure three-dimensional measurement probe according to claim 1, characterized in that: In the initial state, the center of the electrode ball (2) coincides with the center of the ball socket; the center of the electrode ball (2) is located on the central axis of the sampling rod (3).

7. The method for detection direction identification and deformation compensation of a microstructure three-dimensional measurement probe as described in claim 2, characterized in that: Includes the following steps: Step 1: Detect the capacitance values ​​C1 to C5 between the five spherical electrode plates and the electrode ball (2); Step 2: Construct the dimensionless offset of the solution electrode sphere (2) The system of equations is as follows: ； Wherein, θ1 is half of the cone angle of the spherical cone corresponding to the spherical cap surface on the first spherical electrode plate (1-1); Let x be the angle between the line connecting the point closest to the x-axis on the first spherical electrode plate (1-1) and the origin, and the x-axis. R0 is the angle between the line connecting the point furthest from the x-axis on the first spherical electrode plate (1-1) and the origin, and the x-axis; R0 is the radius of the concave spherical cap surface of each spherical electrode plate. The initial capacitance value between the fifth spherical electrode plate (1-5) and the electrode ball (2); , , The expressions are as follows: ； in, ; Based on the dimensionless offset of the electrode ball (2) Calculate the displacement of electrode ball (2) ;in, , , ; Step 3: Calculate the displacement of the ball (6) in the X, Y, and Z axes. , , : ； ； ； Wherein, k is the lever amplification factor, the value of which is equal to the ratio of the distance from the center of the electrode ball (2) to the suspension mechanism (4) to the distance from the center of the contact ball (6) to the suspension mechanism (4); , , It is the offset of electrode ball (2); , , ) is the triaxial elastic offset component of the ball contact (6).

8. The method for detection direction identification and deformation compensation of a microstructure three-dimensional measurement probe according to claim 7, characterized in that: The triaxial elastic offset component of the ball contact (6) , , The expression for ) is as follows: ； Where u is the total elastic offset of the ball (6), γ is the angle between the axis of the sampling rod (3) and the Z-axis; γ is the angle between the projection of the sampling rod (3) onto the XOY plane and the X-axis; l is the length of the contact section (3-2) of the sampling rod (3); included angle The expression is as follows: ； The expression for the included angle γ is as follows: ； The expression for the total elastic offset u at ball contact (6) is as follows: ； in, t is the tangential component of the gravity of the electrode ball (2) along the sampling rod (3); t is the shear elastic coefficient of the contact section (3-2) of the sampling rod (3).

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