A method for simultaneously detecting angular displacement and radial eccentricity of large hollow gears

Abstract

This invention relates to the field of electromagnetic detection, specifically disclosing a method for simultaneously detecting the angular displacement and radial eccentricity of a large hollow gear. The method includes: installing an embedded angular displacement sensor at a fixed distance from the addendum circle of the large hollow gear; applying sinusoidal and cosine alternating current excitation to the sensor's excitation windings; sensing magnetic field changes and outputting standing wave signals through the sensor's sensing windings; superimposing the standing wave signals output from each sensing winding to obtain a traveling wave signal; and detecting the phase and amplitude of the traveling wave signal through an embedded angular displacement sensor signal processing system to calculate the angular displacement and radial eccentricity of the gear under eccentric conditions. This invention directly detects the angular displacement and radial eccentricity of a large hollow gear, effectively overcoming the size limitations of the measured object, achieving multi-parameter composite detection, and improving measurement efficiency.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic detection, and in particular to a method for simultaneously detecting the angular displacement and radial eccentricity of a large hollow gear. Background Technology

[0002] The end effector of large and ultra-large precision machine tools is typically a large hollow gear. Angular displacement and radial eccentricity are important detection parameters for these large hollow gears during operation. Currently, grating-type, steel-grating, and magnetic-grating sensors are widely used in angular displacement detection. However, due to limitations imposed by the size of the measured object and its unique hollow structure, few precision displacement sensors, both domestically and internationally, can directly and simultaneously detect angular displacement and radial eccentricity. Furthermore, most sensors have poor anti-interference capabilities and are susceptible to the effects of strong vibrations and impacts in the working environment, thus affecting their measurement accuracy and making it difficult to meet the requirements for high-precision, multi-parameter composite measurement of angular displacement and radial eccentricity of large hollow gears.

[0003] Embedded angular displacement sensors are sensors based on the principle of electromagnetic coupling. They have advantages such as simple structure, low manufacturing cost, and small size. They also have many advantages such as strong adaptability, resistance to harsh working conditions such as strong vibration and strong impact, and direct detection of the measured object. They are easy to implement multi-parameter measurement and have broad application prospects in measurement.

[0004] Existing angular displacement detection technologies typically employ a method of mounting sensors coaxially with the motor. For example, rotary encoders are often coaxially mounted with the motor shaft, obtaining angular displacement information of the measured object through direct detection. Existing radial eccentricity detection technologies are usually contact-based. For instance, patent CN115615373A discloses a gear radial eccentricity detection device, which includes a gear, a displacement sensor, a detection contact, a measuring column, a cylinder, and a servo motor. This device rotates the gear via the motor, causing the gear teeth to rotate along a trajectory. When the motor drives the gear to rotate one tooth, the measuring cylinder drives the measuring column, whose cylindrical surface is inserted into the tooth groove facing upwards on the gear. This presses against the two sides of the tooth groove at the long shaft end of the gear and onto the detection contact of the displacement sensor. The displacement sensor detects the displacement value, thus achieving the measurement of the radial eccentricity of the gear.

[0005] In addition, among the relevant prior art, CN104298170B discloses a side-mounted precision angular displacement self-detection system, and CN208635714U discloses a precision angular displacement sensing device.

[0006] However, both the aforementioned angular displacement detection technology and radial eccentricity detection technology have the following shortcomings: First, due to the special structure, harsh working environment, and transmission error of large hollow gears, it is difficult to directly measure their angular displacement; second, it is difficult to measure the radial eccentricity of large hollow gears, making it impossible to achieve multi-parameter composite measurement of the object under test.

[0007] Therefore, to solve the above problems, a method for detecting the angular displacement and radial eccentricity of large hollow gears based on electromagnetic coupling is needed, which can simultaneously detect the angular and radial eccentricity of large hollow gears. Summary of the Invention

[0008] In view of this, the purpose of the present invention is to provide a method for simultaneously detecting angular displacement and radial eccentricity of large hollow gears, thereby overcoming the shortcomings of the angular displacement detection technology and radial eccentricity detection technology mentioned in the background art.

[0009] This invention provides a method for simultaneously detecting the angular displacement and radial eccentricity of a large hollow gear, comprising the following steps:

[0010] S1. Arrange the detection system, using a large hollow gear as the rotor, and install an embedded angular displacement sensor at a fixed distance from the tip circle of the large hollow gear, using the embedded angular displacement sensor as the stator.

[0011] S2. Apply sinusoidal and cosine AC excitation to the excitation winding of the embedded angular displacement sensor, respectively;

[0012] S3. The sensing winding of the embedded angular displacement sensor senses the magnetic field change and outputs the standing wave signal respectively;

[0013] S4. Superimpose the standing wave signals output from each induction winding to obtain a traveling wave signal;

[0014] S5. The phase and amplitude of the traveling wave signal are detected by the embedded angular displacement sensor signal processing system, and the angular displacement and radial eccentricity of the large hollow gear under eccentric state are calculated.

[0015] Furthermore, in step S1, the detection system also includes a servo motor, a worm gear, and a worm wheel;

[0016] The power output shaft of the servo motor is fixedly connected to the worm and can drive the worm to rotate; the worm meshes with the worm wheel for transmission; a large hollow gear is parallel and eccentrically positioned above the worm wheel, and the large hollow gear and the worm wheel are fixedly connected; an embedded angular displacement sensor is positioned on the circumferential side of the large hollow gear, and the embedded angular displacement sensor is concentrically set with the worm wheel.

[0017] The embedded angular displacement sensor includes stator teeth and coils; the stator teeth are a section of a ring, and the stator teeth have three axial slots on the side facing the large hollow gear to form four teeth. The four teeth cooperate with the corresponding coils to form sensing units respectively; the coils include sine excitation windings, cosine excitation windings and induction windings.

[0018] Furthermore, the four stator teeth are numbered one, two, three, and four in sequence; the sine excitation winding on tooth one is wound clockwise, the cosine excitation winding is wound clockwise, and the induction winding is wound clockwise; the sine excitation winding on tooth two is wound counterclockwise, the cosine excitation winding is wound counterclockwise, and the induction winding is wound clockwise; the sine excitation winding on tooth three is wound clockwise, the cosine excitation winding is wound counterclockwise, and the induction winding is wound counterclockwise; the sine excitation winding on tooth four is wound counterclockwise, the cosine excitation winding is wound clockwise, and the induction winding is wound counterclockwise.

[0019] Furthermore, in step S2, a sinusoidal AC excitation is applied to the sinusoidal excitation winding of the embedded angular displacement sensor, and a cosine AC excitation is applied to the cosine excitation winding of the embedded angular displacement sensor.

[0020] Furthermore, in step S3, when the large hollow gear rotates, the magnetic field generated by the sine and cosine excitation current is cut, the induction winding senses the change in magnetic field and outputs a standing wave signal.

[0021] The standing wave signals output by the four induction windings are:

[0022]

[0023] In the formula, e 53i N1 represents the standing wave signal output by the i-th induction winding; N2 represents the number of turns of the excitation winding coil of the embedded angular displacement sensor; Λ 54i基 Let A be the fundamental component of the magnetic permeability Fourier series of the i-th sensing unit; Asin(ωt) is the sinusoidal AC excitation applied to the sinusoidal excitation winding of the embedded angular displacement sensor, and Acos(ωt) is the cosine AC excitation applied to the cosine excitation winding of the embedded angular displacement sensor. A represents the amplitude of the excitation signal, ω represents the frequency of the excitation signal, t represents time, and T is the period.

[0024] Furthermore, in step S4, the standing wave signal e 541 With e 543 Superposition, e 532 With e 534 Superimpose the signals to obtain two traveling wave signals, e1 and e2, respectively.

[0025]

[0026] The final traveling wave signal is obtained by superimposing the two traveling wave signals, e1 and e2.

[0027]

[0028] Furthermore, in step S5, the radially eccentric angular displacement in the phase of the final traveling wave signal is calculated by high-frequency pulse interpolation and continuous dynamic phase detection method.

[0029] Furthermore, based on Λ in the final traveling wave signal value 541基 Λ 542基 Λ 543基 Λ 544基 The radial eccentricity of the large hollow gear with radial eccentricity is calculated by reverse calculation.

[0030] Compared with the prior art, the present invention has the following beneficial technical effects:

[0031] First, the present invention provides a method for calculating the angular displacement of a large hollow gear with radial eccentricity. This method can effectively solve the problem that it is difficult to directly measure the angular displacement of a large hollow gear with radial eccentricity due to its special structure, harsh working environment, and transmission error.

[0032] Second, this invention establishes a functional relationship between radial eccentricity and air gap, a functional relationship between air gap and magnetic permeability, and finally establishes a relationship between magnetic permeability and amplitude and phase of traveling wave signal. Based on this, the relationship between the size of radial eccentricity and amplitude of traveling wave signal is obtained. Finally, the size of radial eccentricity is obtained by inversely calculating the amplitude of traveling wave signal.

[0033] Third, the present invention provides a method for simultaneously calculating the angular displacement and the magnitude of the radial eccentricity of a large hollow gear when there is radial eccentricity, thereby realizing multi-parameter composite measurement of the object being measured.

[0034] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0035] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute a limitation thereof.

[0036] Figure 1 This is a structural diagram of the detection system of the present invention;

[0037] Figure 2 for Figure 1 A magnified view of a section at point A in the middle;

[0038] Figure 3This is the front view of an embedded angular displacement sensor.

[0039] Figure 4 Left view of the stator teeth of an embedded angular displacement sensor;

[0040] Figure 5 for Figure 1 Front view of the large hollow gear at point A;

[0041] Figure 6 This is a schematic diagram of the installation of the detection system of the present invention;

[0042] Figure 7 This is a graph showing the single-cycle variation of the sensing unit in an embedded angular displacement sensor.

[0043] Figure 8 This is a rectangular coordinate graph of an involute.

[0044] Figure 9 This is a graph showing the change in air gap distance of the sensing unit after rotation by θ.

[0045] Figure 10 This is a schematic diagram of the magnetic permeability of the sensing unit during a single cycle.

[0046] Figure 11 This is a flowchart of a method for simultaneously detecting angular displacement and radial eccentricity of a large hollow gear according to the present invention. Detailed Implementation

[0047] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments; the accompanying drawings are simplified schematic diagrams and are only used to explain the present invention, and are not intended to limit the present invention.

[0048] Example 1

[0049] This embodiment provides a detection system that can be used to simultaneously detect the angular displacement and radial eccentricity of large hollow gears.

[0050] like Figure 1-5 As shown, the detection system includes a servo motor 1, a worm gear 2, a worm wheel 3, a large hollow gear 4 (which is the object being detected), and an embedded angular displacement sensor 5.

[0051] The power output shaft of the servo motor 1 is fixedly connected to the worm gear 2 and can drive the worm gear 2 to rotate; the worm gear 2 meshes with the worm wheel 3 for transmission, and the rotation of the worm gear 2 drives the worm wheel 3 to rotate; the large hollow gear 4 is parallel and eccentrically positioned above the worm wheel 3, and the large hollow gear 4 is fixedly connected to the worm wheel 3 (for example, it can be connected by bolts), and the rotation of the worm wheel 3 drives the large hollow gear 4 to rotate, wherein the large hollow gear 4 is the rotor; the embedded angular displacement sensor 5 is positioned on the circumferential side of the large hollow gear 4, and the embedded angular displacement sensor 5 is concentrically arranged with the worm wheel 3, wherein the embedded angular displacement sensor 5 is the stator.

[0052] The embedded angular displacement sensor 5 includes a stator tooth 54 (i.e., a magnetic substrate) and a coil; the stator tooth 54 is a segment of a circular ring, and the stator tooth 54 has three axial slots on the side facing the large hollow gear 4 to form four teeth, which are arranged sequentially ( Figure 2 , 3 The four teeth (from right to left) can be designated as tooth number one, tooth number two, tooth number three, and tooth number four. The four teeth cooperate with the corresponding coils to form sensing units 541, 542, 543, and 544, respectively.

[0053] The coil arrangement is as follows Figure 2 As shown, it includes sinusoidal excitation windings 511, 512, 513, and 514, wherein sinusoidal excitation windings 511 and 513 are wound clockwise, and sinusoidal excitation windings 512 and 514 are wound counterclockwise; the coil also includes cosine excitation windings 521, 522, 523, and 524, wherein cosine excitation windings 521 and 524 are wound clockwise, and cosine excitation windings 522 and 523 are wound counterclockwise; the coil also includes induction windings 531, 532, 533, and 534, wherein induction windings 531 and 532 are wound clockwise, and induction windings 533 and 534 are wound counterclockwise.

[0054] The number of turns in the excitation winding coil is denoted as N1, and the number of turns in the induction winding coil is denoted as N2.

[0055] The embedded angular displacement sensor 5, microprocessor (not shown in the figure), signal processing circuit (not shown in the figure), and large hollow gear 4 that rotate relative to each other constitute a self-detection system capable of outputting precise displacement information. The structure of the embedded angular displacement sensor 5 can also be found in CN208635714U.

[0056] In a non-eccentric state, the distance between the inner diameter of the stator tooth 54 and the air gap at the tip circle of the large hollow gear 4 is lg, and one tooth and one slot of the large hollow gear 4 form a spatial period T; the tooth width s of the stator tooth 54 of the embedded angular displacement sensor 5 is equal to the pitch circle tooth width L of the large hollow gear 4. zg They are equal, that is, s = L zgThe stator tooth 54 slot width e = 3L of the embedded angular displacement sensor 5 zg / 2, the stator teeth 54 of the embedded angular displacement sensor 5 have a tooth thickness of W. b .

[0057] The detection system applies sinusoidal and cosine alternating current excitation to the excitation winding of the embedded angular displacement sensor 5, respectively. The sensor sensing winding senses the magnetic field change and outputs standing wave signals. The standing wave signals output by each sensing winding are superimposed to obtain a traveling wave signal. The phase and amplitude of the traveling wave signal are detected by the embedded angular displacement sensor signal processing system, and the angular displacement and radial eccentricity of the gear under eccentricity can be calculated.

[0058] This detection system can directly detect the angular displacement and radial eccentricity of large hollow gears. It can also effectively overcome the size limitations of the measured object, realize multi-parameter composite detection, and improve measurement efficiency.

[0059] Example 2

[0060] This embodiment provides a method for simultaneously detecting the angular displacement and radial eccentricity of a large hollow gear, which generally includes the following steps:

[0061] S1. Arrange the detection system, using a large hollow gear as the rotor, and install an embedded angular displacement sensor at a fixed distance from the tip circle of the large hollow gear, using the embedded angular displacement sensor as the stator.

[0062] S2. Apply sinusoidal and cosine AC excitation to the excitation winding of the embedded angular displacement sensor, respectively;

[0063] S3. The sensing winding of the embedded angular displacement sensor senses the magnetic field change and outputs the standing wave signal respectively;

[0064] S4. Superimpose the standing wave signals output from each induction winding to obtain a traveling wave signal;

[0065] S5. The phase and amplitude of the traveling wave signal are detected by the embedded angular displacement sensor signal processing system, and the angular displacement and radial eccentricity of the large hollow gear under eccentric state are calculated.

[0066] The steps above are now broken down in detail.

[0067] The detection system in this embodiment is the same as the detection system provided in Embodiment 1.

[0068] like Figure 6As shown, the embedded angular displacement sensor 5 is installed concentrically with the center O of the worm gear 3, and the large hollow gear 4 is installed on the worm gear 3. When the worm gear 3 rotates by θ, the large hollow gear 4 also rotates by θ. For ease of discussion, a rectangular coordinate system is established. When the large hollow gear 4 is eccentric, the center O' of the large hollow gear 4 has an angle α with the X-axis, and the eccentric distance OO' is D. The trajectory of the center O' of the large hollow gear 4 after eccentricity is a circular motion with O as the center and radius D.

[0069] like Figure 7 As shown, the periodic change of the tooth groove of the large hollow gear 4 during rotation will cause the change of air gap magnetic permeability of the sensing unit of the embedded angular displacement sensor 5. The change of a single cycle (one tooth and one groove of the gear is one cycle) is calculated by the air gap magnetic permeability analytical method. The process of the sensing unit 541 rotating the gear 4 in a single cycle is divided into state 1, state 2, state 3 and state 4. By transforming the reference coordinate system, the counterclockwise rotation of the large hollow gear 4 is regarded as the clockwise rotation of a single sensing unit 541 of the embedded angular displacement sensor 5. Figure 7 It contains four states. Taking states 1 to 2 as an example, the air gap is solved analytically for states 1 to 2. The air gap magnetic permeability is divided into three parts, namely (θ0,θ1), (θ1,θ2), and (θ2,θ3). The air gap magnetic permeability corresponding to the involute tooth profile of the large hollow gear 4 is denoted as Λ1, Λ2, and Λ3, respectively.

[0070] Figure 8 This is a rectangular coordinate graph of an involute, with angle θ. k Let θ be the development angle of point K on the involute. k When the calculation starts at point A (which lies on the base circle), the angle θ is... k It is both a corner and a turning point.

[0071] like Figure 9 As shown, due to the eccentricity D, the air gap distance of sensing unit 541 after rotation θ is:

[0072]

[0073] Where: lg is the distance between the stator tooth inner diameter and the air gap at the gear tip circle when the large hollow gear is in a non-eccentric state; r a The radius of the tip circle of a large hollow gear; r b α is the pitch circle radius of the large hollow gear; D is the eccentricity distance between the large hollow gear and the worm gear; α is the angle between the line connecting the center of the large hollow gear and the center of the worm gear in the eccentric state and the X-axis; β2 is the angle between the line connecting the center of the large hollow gear and the center of the worm gear and the Y-axis after the large hollow gear rotates by θ; θ is the gear rotation angle, α k This refers to the pressure angles corresponding to different angles on the involute of a large hollow gear.

[0074] Sensing unit 541 is in states 1 to 2. Let θ0 be the starting position of the left tooth profile (θ0, θ1), and the rotation angle range θ∈(θ0-0, θ1-θ0). Divide the (θ0, θ1) portion into N equal parts (N is an integer), with each part occupying an angle of... When the angle rotated is θ, the number of parts represented by the angle rotated is... The remaining angle that has not been rotated is (θ1-θ0)-θ, and the remaining percentage is... Therefore, after rotating θ, the air gap magnetic permeability Λ1 corresponding to the involute tooth profile of the large hollow gear 4 can be expressed as:

[0075]

[0076] Wherein: Λ1 is the air gap magnetic permeability corresponding to the involute tooth profile of the large hollow gear. The air gap permeability is the value for each fraction of the remaining angle that has not been rotated.

[0077] According to the magnetic permeability calculation formula We can obtain Λ1:

[0078]

[0079] Where: μ0 is the free magnetic permeability, W b r is the thickness of the stator teeth. ra+lg The sum of the inner diameter radius of the stator teeth and the tip circle radius of the large hollow gear.

[0080]

[0081]

[0082] θ′ is the development angle from the base circle to the root circle, and its magnitude is:

[0083]

[0084] Where z is the number of teeth of the large hollow gear, and ha* and c* are the tooth tip height coefficient and tooth clearance coefficient, respectively.

[0085] α 根 The pressure angle corresponding to the root circle of a large hollow gear:

[0086]

[0087] Where, r b For the pitch circle of a large hollow gear, r f denoted as the root circle of the large hollow gear, and m as the module of the large hollow gear.

[0088] Since Λ1 acts on the involute tooth profile, the pressure angle α can be obtained by inverse calculation based on the involute equation.k .

[0089] The air gap magnetic permeability Λ1 includes radial eccentricity D and eccentricity angle α.

[0090] State 1 to State 2 consists of Λ1, Λ2, and Λ3. Similarly, the analytical expressions for Λ2 and Λ3 can be derived from the derivation process of Λ1.

[0091] The total magnetic permeability of Λ1, Λ2, and Λ3 in states 1 to 2 is denoted as Λ. 123 :

[0092]

[0093] Figure 7 The magnetic permeability of phases 2 to 3, 3 to 4, and 4 to the next cycle is denoted as Λ. 456 Λ 789 Λ 101112 .

[0094] Figure 10 The diagram shows the magnetic permeability of the sensing unit within a single cycle. Let Λ represent the total magnetic permeability across the four stages, and calculate its Fourier series:

[0095]

[0096] Where T is a spatial cycle of one tooth and one groove in a large hollow gear.

[0097] Take the fundamental component in the permeability Fourier series To calculate the induced electromotive force, use the induced voltage formula:

[0098]

[0099] Wherein, N1 and N2 are the number of turns of the excitation winding coil and the number of turns of the induction winding coil, respectively.

[0100] Figure 2 When the sinusoidal excitation current i = Asin(ωt) is input to the excitation winding 511 of the sensing unit 541, the standing wave output by the induction winding 531 is:

[0101]

[0102] Figure 2 When the cosine excitation current i = Acos(ωt) is input to the excitation winding 521 of the sensing unit 541, the standing wave output by the induction winding 531 is:

[0103]

[0104] By superimposing the two standing wave signals, the standing wave signal can be obtained:

[0105]

[0106] e 541 The standing wave signal generated by induction winding 541 is the same as the standing wave signal generated by induction windings 531, 532, 533, and 534.

[0107]

[0108] In the formula, e 53i N1 represents the standing wave signal output by the i-th induction winding; N2 represents the number of turns of the excitation winding coil of the embedded angular displacement sensor; Λ 54i基 Let A be the fundamental component of the magnetic permeability Fourier series of the i-th sensing unit; Asin(ωt) is the sinusoidal AC excitation applied to the sinusoidal excitation winding of the embedded angular displacement sensor, and Acos(ωt) is the cosine AC excitation applied to the cosine excitation winding of the embedded angular displacement sensor. A represents the amplitude of the excitation signal, ω represents the frequency of the excitation signal, t represents time, and T is the period.

[0109] e 541 With e 543 Superposition, e 532 With e 534 The superposition yields two traveling wave signals, e1 and e2:

[0110]

[0111]

[0112] Based on trigonometric auxiliary formulas:

[0113]

[0114] The final traveling wave signal is obtained by superimposing the two traveling waves, e1 and e2.

[0115]

[0116] The final traveling wave signal amplitude is:

[0117]

[0118] Λ in induced voltage signal 541基 Λ 542基 Λ 543基 Λ 544基 These are the fundamental magnetic permeance calculated using the analytical method. The formula for calculating magnetic permeance is:

[0119] The derivation shows that radial eccentricity affects the air gap lg at the rotation angle θ, and the change in the air gap lg causes a change in l in the magnetic permeability calculation formula.

[0120] A functional relationship was found between the radial eccentricity and the magnetic permeability Λ. This relationship was then used to inversely calculate Λ in the amplitude of the induced signal. 541基 Λ 542基 Λ 543基 Λ 544基 The radial eccentricity of the large hollow gear 4 with radial eccentricity can be calculated.

[0121] The final traveling wave signal phase is:

[0122] The angular displacement information of the large hollow gear 4 with radial eccentricity can be calculated by high-frequency pulse interpolation and continuous dynamic phase detection.

[0123] Finally, it should be noted that this article uses specific examples to illustrate the principles and implementation methods of the present invention. The above description of the embodiments is only for the purpose of helping to understand the core ideas of the present invention. Without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. A method for simultaneously detecting the angular displacement and radial eccentricity of a large hollow gear, characterized in that, Includes the following steps: S1. Arrange the detection system, using a large hollow gear as the rotor, and install an embedded angular displacement sensor at a fixed distance from the tip circle of the large hollow gear, using the embedded angular displacement sensor as the stator. S2. Apply sinusoidal and cosine AC excitation to the excitation winding of the embedded angular displacement sensor, respectively; S3. The sensing winding of the embedded angular displacement sensor senses the magnetic field change and outputs the standing wave signal respectively; S4. Superimpose the standing wave signals output from each induction winding to obtain a traveling wave signal; S5. The phase and amplitude of the traveling wave signal are detected by the embedded angular displacement sensor signal processing system, and the angular displacement and radial eccentricity of the large hollow gear under eccentricity are calculated. In step S1, the detection system further includes a servo motor, a worm gear, and a worm wheel; The power output shaft of the servo motor is fixedly connected to the worm and can drive the worm to rotate; the worm meshes with the worm wheel for transmission; a large hollow gear is parallel and eccentrically positioned above the worm wheel, and the large hollow gear and the worm wheel are fixedly connected; an embedded angular displacement sensor is positioned on the circumferential side of the large hollow gear, and the embedded angular displacement sensor is concentrically set with the worm wheel. The embedded angular displacement sensor includes stator teeth and coils; the stator teeth are a section of a ring, and the stator teeth have three axial slots on the side facing the large hollow gear to form four teeth. The four teeth cooperate with the corresponding coils to form sensing units; the coils include a sine excitation winding, a cosine excitation winding, and an induction winding. The four stator teeth are numbered one, two, three, and four, respectively. On tooth one, the sine excitation winding is wound clockwise, the cosine excitation winding is wound clockwise, and the induction winding is wound clockwise. On tooth two, the sine excitation winding is wound counterclockwise, the cosine excitation winding is wound counterclockwise, and the induction winding is wound clockwise. On tooth three, the sine excitation winding is wound clockwise, the cosine excitation winding is wound counterclockwise, and the induction winding is wound counterclockwise. On tooth four, the sine excitation winding is wound counterclockwise, the cosine excitation winding is wound clockwise, and the induction winding is wound counterclockwise. In step S3, when the large hollow gear rotates, the magnetic field generated by the sine and cosine excitation current is cut, the induction winding senses the change in magnetic field and outputs a standing wave signal. The standing wave signals output by the four induction windings are: In the formula, This represents the standing wave signal output by the i-th induction winding; N 1 represents the number of turns in the excitation winding coil of the embedded angular displacement sensor. N 2 represents the number of turns in the induction winding coil; Let Asin( be the fundamental component of the Fourier series of the magnetic permeability of the i-th sensing unit; ωt To apply a sinusoidal alternating current excitation to the sinusoidal excitation winding of an embedded angular displacement sensor, Acos( ωt To apply cosine alternating current excitation to the cosine excitation winding of the embedded angular displacement sensor, A represents the amplitude of the excitation signal. The frequency of the excitation signal is represented by t, and time is represented by t. T is the period; In step S4, the standing wave signal e 541 and e 543 Superimposed, e 532 and e 534 Superimposed, two traveling wave signals are obtained respectively. e 1 and e 2; Will e 1 and e 2. The final traveling wave signal is obtained by superimposing the two traveling wave signals: Based on Λ in the final traveling wave signal value 541基 Λ 542基 Λ 543基 Λ 544基 The radial eccentricity of the large hollow gear with radial eccentricity is calculated by reverse calculation.

2. The method for simultaneously detecting angular displacement and radial eccentricity of a large hollow gear according to claim 1, characterized in that: In step S2, a sinusoidal AC excitation is applied to the sinusoidal excitation winding of the embedded angular displacement sensor, and a cosine AC excitation is applied to the cosine excitation winding of the embedded angular displacement sensor.

3. The method for simultaneously detecting angular displacement and radial eccentricity of a large hollow gear according to claim 1, characterized in that: In step S5, the radially eccentric angular displacement in the phase of the final traveling wave signal is calculated by high-frequency pulse interpolation and continuous dynamic phase detection method.

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