Single-loop absolute time grating angular displacement sensor and absolute angular displacement value measuring system and method

Abstract

The invention discloses a single-ring absolute time grating angular displacement sensor and an absolute angular displacement value measuring system and method.The single-ring absolute time grating angular displacement sensor comprises a stator base body and a rotor base body, the rotor base body is provided with an induction electrode assembly and a reflection electrode assembly, and the stator base body is provided with an excitation electrode assembly and a receiving electrode assembly; the differential induction electrode assembly and the excitation electrode assembly are connected with the channel selector. The absolute angular displacement value measuring system comprises a single-circle absolute time grating angular displacement sensor with controllable electrode cycle number, a subtraction circuit, a shaping circuit and an FPGA signal processing system. According to the scheme, a single-loop absolute design is adopted, absolute coding of each position in the whole measuring range is achieved, the number of electrode cycles can be flexibly controlled, compared with a double-loop structure, the loop width, the circuit cost and the decoding and coding mode are greatly improved, and meanwhile the industrial use environment adaptability is improved.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a single-turn absolute time-grating angular displacement sensor, an absolute angular displacement value measurement system and method. Background Art

[0002] High-precision displacement measurement devices are used in precision measurement fields such as ultra-precision CNC machine tools, intelligent manufacturing equipment, and national defense and military industries. Core technology is the "eye" to achieve high-precision positioning and control. Traditional precision displacement measurement usually uses gratings, magnetic gratings, The accuracy and resolution of the gate sensors such as capacitive gates are subject to the complex and rigorous engraving process and electronic segmentation technology. The sensor cost is high and its anti-interference ability is weak.

[0003] In recent years, a new type of nano time-grating angular displacement sensor based on the "space-time conversion theory" has been proposed in China. The measurement of the time-grating angular displacement sensor is achieved through the relative parallel rotation of the rotor base and the stator base. The alternating electric field motion reference system of the rotor base and the stator base converts the position difference between the two points into the time difference, thereby realizing the conversion of the measurement reference from equal division of space to equal division of time.

[0004] Time-grating angular displacement sensors can be divided into incremental and absolute encoding methods. For incremental time-grating angular displacement sensors, the incremental counting method requires a reference zero position to be set in advance, and the absolute displacement is calculated by the relative displacement with the reference point. This power-on reset method seriously affects the measurement efficiency. The absolute time-grating angular displacement sensor has become a development trend because of its advantages such as no need to reset when powered on, immediate acquisition of absolute position and no cumulative error. However, the current absolute time-grating angular displacement sensor requires at least two single-code incremental sensors to obtain absolute position information. For some small-diameter or large hollow mechanical shaft transmission systems, a smaller ring width structure is often required to meet the actual application requirements, which limits the application of absolute time-grating angular displacement sensors in these occasions. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is: how to provide a single-turn absolute time-grating angular displacement sensor, an absolute angular displacement value measurement system and method that can effectively reduce the ring width on the basis of satisfying the absolute measurement of the displacement value and meet the application requirements of more occasions.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: A single-turn absolute time-grid angular displacement sensor with controllable electrode period number comprises a stator substrate and a rotor substrate, wherein the surface of the rotor substrate facing the stator substrate is provided with an induction electrode assembly and a reflection electrode assembly, wherein the differential induction electrode assembly comprises a plurality of induction pole pieces uniformly distributed on the rotor substrate along the circumferential direction, wherein the surface of the stator substrate facing the rotor substrate is provided with an excitation electrode assembly and a receiving electrode assembly, wherein the excitation electrode assembly comprises a plurality of excitation pole pieces uniformly distributed on the stator substrate along the circumferential direction, wherein both the differential induction electrode assembly and the excitation electrode assembly are connected to a channel selector, wherein the differential induction electrode assembly forms a first induction electrode assembly or a second induction electrode assembly that is turned on according to different induction pole pieces selected by the channel selector, and wherein the excitation electrode assembly forms a first excitation electrode assembly or a second excitation electrode assembly that is turned on according to different excitation pole pieces selected by the channel selector.

[0007] Preferably, the excitation pole pieces are in a fan-shaped ring structure, and the excitation pole pieces are arranged at equal intervals along the circumferential direction of the stator substrate, and the radial heights of the excitation pole pieces are the same, and the central angles are equal; The induction pole pieces are of a double sinusoidal structure, and the induction pole pieces are arranged at equal intervals along the circumferential direction of the rotor substrate, and the radial heights of the induction pole pieces are the same, and the central angles are equal; The central angle of the circle opposite to the sensing pole piece is equal to the central angle of the circle opposite to the exciting pole piece, and the central angle of the circle between two adjacent sensing pole pieces is twice the central angle of the circle between two adjacent exciting pole pieces.

[0008] Preferably, in the first excitation electrode assembly, every four adjacent excitation pole pieces form a pole pair, and there are M pole pairs in total, wherein the excitation pole pieces No. 4n1+1 are connected into a group to form an A1 excitation phase, the excitation pole pieces No. 4n1+2 are connected into a group to form a B1 excitation phase, the excitation pole pieces No. 4n1+3 are connected into a group to form a C1 excitation phase, and the excitation pole pieces No. 4n1+4 are connected into a group to form a D1 excitation phase, wherein n1 is all integers from 0 to M-1 in sequence; In the second excitation electrode assembly, all excitation pole pieces form a pair of poles, with a total of 1 pair of poles, the 1st, 2nd, ...n2th excitation pole pieces are connected into a group to form an A2 excitation phase, the n2+1st, n2+2nd, ...2n2th excitation pole pieces are connected into a group to form a B2 excitation phase, the 2n2+1st, 2n2+2nd, ...3n2th excitation pole pieces are connected into a group to form a C2 excitation phase, the 3n2+1st, 3n2+2nd, ...4n2th excitation pole pieces are connected into a group to form a D2 excitation phase, wherein n2=M; In the first sensing electrode assembly, every two adjacent sensing electrode pieces form a pair of electrodes, and there are M pairs of electrodes in total. The sensing electrode pieces No. 2n3+1 are connected into a group to form an A1 sensing group, and the sensing electrode pieces No. 2n3+2 are connected into a group to form a B1 sensing group, wherein n3 is all integers from 0 to M-1 in sequence; In the second sensing electrode assembly, all sensing pole pieces form a pair of poles, with a total of 1 pair of poles. The 1st, 2nd, ...n4th sensing pole pieces are connected into a group to form an A2 sensing group, and the n4+1st, n4+2nd, ...2n4th sensing pole pieces are connected into a group to form a B2 sensing group, where n4=M.

[0009] Preferably, in the first excitation electrode assembly, every 4n6 adjacent excitation electrode pieces form a counter electrode, and there are N counter electrodes in total; The excitation poles n5*4n6+1, n5*4n6+2, ...n5*4n6+n6 are connected as a group to form the A1 excitation phase. The excitation poles n5*4n6+n6+1, n5*4n6+n6+2, ...n5*4n6+2n6 are connected as a group to form the B1 excitation phase. The excitation poles n5*4n6+2n6+1, n5*4n6+2n6+2, ...n5*4n6+3n6 are connected as a group to form the C1 excitation phase. The excitation pole pieces n5*4n6+3n6+1, n5*4n6+3n6+2, ...n5*4n6+4n6 are connected as a group to form the D1 excitation phase, n5 takes all integers from 0 to N-1, and n6=N-1; In the second excitation electrode assembly, each adjacent 4n8 excitation electrode pieces form a pair of electrodes, and there are N-1 pairs of electrodes in total; Connect the excitation pole pieces No. n7*4n8+1, n7*4n8+2, ...n7*4n8+n8 into a group to form the A2 excitation phase; The excitation pole pieces No. n7*4n8+n8+1, n7*4n8+n8+2, ...n7*4n8+2n8 are connected as a group to form the B2 excitation phase; The excitation pole pieces n7*4n8+2n8+1, n7*4n8+2n8+2, ...n7*4n8+3n8 are connected as a group to form the C2 excitation phase; The excitation pole pieces n7*4n8+3n8+1, n7*4n8+3n8+2, ...n7*4n8+4n8 are connected as a group to form the D2 excitation phase, n7 is all integers from 0 to N-2, n8=N; In the first sensing electrode assembly, each adjacent 2n 10The inductive pole pieces form a pair of poles, and there are N pairs of poles in total; The n9*2n 10 +1, n9*2n 10 +2,... n9*2n 10 +n 10 The induction electrodes are connected into a group to form the A1 induction group. No. n9*2n 10 +n 10 +1, n9*2n 10 +n 10 +2,... n9*2n 10 +n 10 +2n 10 The sensing electrodes are grouped together to form the B1 sensing group; n9 takes all integers from 0 to N-1, n 10 =N-1; In the second sensing electrode assembly, each adjacent 2n 12 The inductive pole pieces form a pair of poles, and there are N-1 pairs of poles in total; The nth 11 *2n 12 +1, n 11 *2n 12 +2, ... n 11 *2n 12 +n 12 The sensing electrodes are connected into a group to form the A2 sensing group; No.n 11 *2n 12 +n 12 +1, n 11 *2n 12 +n 12 +2, ...n 11 *2n 12 +2n 12 The sensing electrodes are connected into a group to form a B2 sensing group; 11 Take all integers from 0 to N-2, n 12 =N.

[0010] Preferably, the reflecting electrode assembly comprises a first annular reflecting pole piece and a second annular reflecting pole piece which are arranged concentrically, and the receiving electrode assembly comprises a first annular receiving pole piece and a second annular receiving pole piece which are arranged concentrically, the first annular reflecting pole piece and the first annular receiving pole piece are directly opposite to each other, and the second annular reflecting pole piece and the second annular receiving pole piece are directly opposite to each other; The first annular reflective pole piece is connected to the A1 sensing group and the A2 sensing group, and the second annular reflective pole piece is connected to the B1 sensing group and the B2 sensing group.

[0011] Preferably, the channel selector comprises a sensing electrode channel selector and an excitation electrode channel selector, the sensing electrode channel selector is a dual-channel single-pole single-throw switch, and the excitation electrode channel selector is a dual-channel single-pole single-throw switch or a multi-way data selector.

[0012] An absolute angular displacement value measurement system, comprising the above-mentioned single-turn absolute time-grid angular displacement sensor with controllable electrode period number, a subtraction circuit, a shaping circuit and an FPGA signal processing system; The signal output end of the single-turn absolute time-grid angular displacement sensor is connected to the signal input end of the subtraction circuit; The signal output end of the subtraction circuit is connected to the signal input end of the shaping circuit, and the subtraction circuit synthesizes the traveling wave signal output by the single-turn absolute time-grid angular displacement sensor into two differential sine wave signals and outputs them to the shaping circuit; The signal output end of the shaping circuit is connected to the input end of the FPGA signal processing system, and the shaping circuit shapes the two differential sinusoidal wave signals output by the subtraction circuit into two square wave signals and outputs them to the FPGA signal processing system, and the shaping circuit also transforms the same-frequency reference sinusoidal signal into a square wave signal and outputs it to the FPGA signal processing system; The FPGA signal processing system includes a precise angular displacement value calculation module, a coarse angular displacement value calculation module and an absolute angular displacement value calculation module. The precise angular displacement value calculation module is used to obtain a precise angular displacement value according to the output signal of the shaping circuit, the coarse angular displacement value calculation module is used to obtain a coarse angular displacement value according to the output signal of the shaping circuit, and the absolute angular displacement value calculation module is used to obtain an absolute angular displacement value according to the precise angular displacement value and the coarse angular displacement value.

[0013] A method for measuring an absolute angular displacement value, using the above-mentioned absolute angular displacement value measuring system, comprises the following steps: Step 1) The rotor base and the stator base rotate relatively parallel to each other, the channel selector is used to cut off the first sensing electrode assembly and the first excitation electrode assembly, and the second sensing electrode assembly and the second excitation electrode assembly are turned on at the same time, and four sinusoidal excitation signals of the same frequency and amplitude with a phase difference of 90° are applied to the second excitation electrode assembly. The sinusoidal excitation signals are coupled to the electric field between the second excitation electrode assembly and the second sensing electrode assembly to generate two sinusoidal traveling wave signals of the same frequency and amplitude with a phase difference of 180° on the second sensing electrode assembly. The two sinusoidal traveling wave signals are reflected to the receiving electrode assembly by the reflecting electrode assembly, and the first traveling wave signal and the second traveling wave signal are output on the receiving electrode assembly. The first traveling wave signal and the second traveling wave signal are synthesized into a first differential sinusoidal traveling wave signal U by a subtraction circuit. o1, the first differential sinusoidal traveling wave signal U o1 After being shaped into a square wave by a shaping circuit, it is stored in the RAM of the FPGA signal processing system; Step 2) using the channel selector to quickly cut off the second sensing electrode assembly and the second excitation electrode assembly, and turn on the first sensing electrode assembly and the first excitation electrode assembly, and the four-way sinusoidal excitation signals with the same frequency and amplitude and the same phase difference of 90° as in step 1) are sequentially transmitted, and the sinusoidal excitation signals are coupled to the electric field between the first excitation electrode assembly and the first sensing electrode assembly to generate two sinusoidal traveling wave signals with the same frequency and amplitude and a phase difference of 180° on the first sensing electrode assembly, and the two sinusoidal traveling wave signals are reflected to the receiving electrode assembly through the reflecting electrode assembly, and the third traveling wave signal and the fourth traveling wave signal are output on the receiving electrode assembly, and the third traveling wave signal and the fourth traveling wave signal are synthesized into the second differential sinusoidal traveling wave signal U through the subtraction circuit. o2 ; Step 3) The second differential sinusoidal traveling wave signal U o2 A reference sinusoidal signal U with the same frequency and fixed phase r After being shaped into a square wave by a shaping circuit, it is sent to the precise angular displacement value in the FPGA signal processing system for calculation to obtain the precise angular displacement value; At the same time, the second differential sinusoidal traveling wave signal U o2 After being shaped into a square wave by the shaping circuit, the first differential sinusoidal traveling wave signal U shaped into a square wave o1 The rough angular displacement value is sent to the rough angular displacement value calculation module of the FPGA signal processing system to calculate the rough angular displacement value; The absolute angular displacement value calculation module of the FPGA signal processing system calculates the absolute angular displacement value based on the precise angular displacement value and the coarse angular displacement value and then outputs it.

[0014] Preferably, in step 1), four sinusoidal excitation signals of the same frequency and amplitude with a phase difference of 90° are applied to the A2 excitation phase, B2 excitation phase, C2 excitation phase and D2 excitation phase of the second excitation electrode assembly respectively. The sinusoidal excitation signals are coupled to the electric field between the second excitation electrode assembly and the second induction electrode assembly to generate two sinusoidal traveling wave signals of the same frequency and amplitude with a phase difference of 180° on the A2 induction group and the B2 induction group of the second induction electrode assembly respectively. The two sinusoidal traveling wave signals are reflected to the first annular receiving electrode piece and the second annular receiving electrode piece respectively by the first annular reflecting electrode piece and the second annular reflecting electrode piece, and the first traveling wave signal is output on the first annular receiving electrode piece, and the second traveling wave signal is output on the second annular receiving electrode piece. The first traveling wave signal and the second traveling wave signal are synthesized into a first differential sinusoidal traveling wave signal U by a subtraction circuit. o1 , the first differential sinusoidal traveling wave signal U o1After being shaped into a square wave by a shaping circuit, it is stored in the RAM of the FPGA signal processing system; In step 2), four sinusoidal excitation signals of the same frequency and amplitude with a phase difference of 90° are applied to the A1 excitation phase, B1 excitation phase, C1 excitation phase and D1 excitation phase of the first excitation electrode assembly respectively. The sinusoidal excitation signals are coupled to the electric field between the first excitation electrode assembly and the first induction electrode assembly to generate two sinusoidal traveling wave signals of the same frequency and amplitude with a phase difference of 180° on the A1 induction group and the B1 induction group of the first induction electrode assembly respectively. The two sinusoidal traveling wave signals are reflected to the first annular receiving electrode piece and the second annular receiving electrode piece respectively by the first annular reflecting electrode piece and the second annular reflecting electrode piece, and a third traveling wave signal is output on the first annular receiving electrode piece, and a fourth traveling wave signal is output on the second annular receiving electrode piece. The third traveling wave signal and the fourth traveling wave signal are synthesized into a second differential sinusoidal traveling wave signal U by a subtraction circuit. o2 .

[0015] Preferably, in step 3), the second differential sinusoidal traveling wave signal U o2 A reference sinusoidal signal U with the same frequency and fixed phase r After being shaped into a square wave by the shaping circuit, it is sent to the precise angular displacement value calculation module in the FPGA signal processing system for phase comparison. The phase difference after phase comparison is represented by the number of interpolated high-frequency clock pulses, and the precise angular displacement value is obtained after transformation. At the same time, the second differential sinusoidal traveling wave signal U o2 After being shaped into a square wave by the shaping circuit, it is sent to the rough angular displacement value calculation module of the FPGA signal processing system and combined with the first differential sinusoidal traveling wave signal U shaped into a square wave. o1 The phase difference after phase comparison is the same as the phase difference of the reference sinusoidal signal U with the same frequency and fixed phase that is shaped into a square wave. r Then the phase comparison is performed, and the phase difference after the phase comparison is represented by the number of interpolated high-frequency clock pulses, and the rough angular displacement value is obtained after transformation; The absolute angular displacement value calculation module of the FPGA signal processing system calculates the absolute angular displacement value based on the precise angular displacement value and the coarse angular displacement value and then outputs it.

[0016] Compared with the prior art, the present invention aims at the absolute measurement requirements of the existing single-channel incremental time-grating sensor in practical applications, and proposes an absolute time-grating angular displacement sensor and an absolute angular displacement measurement system and method based on a single-circuit electrode period controllable structure. The present invention only uses a single-channel electrode structure, and uses a channel selector to time-select the working state of the electrodes at each position to be turned on or off, so as to realize the absolute displacement value measurement of the time-grating angular displacement sensor. Therefore, this scheme adopts a single-circuit absolute design, and uses differential and reflection structures, which not only realizes the absolute encoding of each position within the entire range, but also the number of electrode periods can be flexibly controlled. Compared with the double-circuit structure, its loop width, circuit cost and decoding and encoding methods are greatly improved, and at the same time, it also improves the adaptability to the industrial use environment and can meet the application requirements of more occasions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Attached Figure 1 It is a structural schematic diagram of a single-turn absolute time-grating angular displacement sensor of the present invention; Attached Figure 2 It is a structural schematic diagram of the stator matrix in the single-turn absolute time-grid angular displacement sensor of the present invention; Attached Figure 3 It is a schematic structural diagram of the rotor base in the single-turn absolute time-grating angular displacement sensor of the present invention; Attached Figure 4 It is a connection diagram of a channel selector in a single-turn absolute time-grid angular displacement sensor of the present invention; Attached Figure 5 It is a system block diagram of the absolute angular displacement value measurement system of the present invention.

[0018] Explanation of the reference numerals: rotor base 1 , first annular reflective pole piece 101 , second annular reflective pole piece 102 , inductive pole piece 103 , stator base 2 , first annular receiving pole piece 201 , second annular receiving pole piece 202 , exciting pole piece 203 . DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0020] It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invention product is usually placed when used, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In addition, the terms "horizontal", "vertical", etc. do not mean that the components are absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted. In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] The present invention provides a single-turn absolute time-grating angular displacement sensor with controllable electrode period number, as shown in the attached Figure 1 To the attached Figure 3 As shown, it includes a stator base 2 and a rotor base 1, the stator base 2 and the rotor base 1 are coaxially installed, and the upper surface of the stator base 2 is parallel to the lower surface of the rotor base 1 and maintains a certain gap.

[0022] An induction electrode assembly and a reflection electrode assembly are provided on the surface of the rotor base 1 facing the stator base 2. The reflection electrode assembly includes a first annular reflection pole piece 101 and a second annular reflection pole piece 102 which are arranged concentrically. The first annular reflection pole piece 101 is connected to the A1 induction group and the A2 induction group, and the second annular reflection pole piece 102 is connected to the B1 induction group and the B2 induction group. The differential induction electrode assembly includes a plurality of induction pole pieces 103 uniformly distributed on the rotor base 1 along the circumferential direction. The induction pole pieces 103 are in a double sinusoidal structure. Each induction pole piece 103 is arranged at equal intervals along the circumferential direction of the rotor base 1, and each induction pole piece 103 has the same radial height and the same central angle. The surface of the stator base 2 facing the rotor base 1 is provided with an excitation electrode assembly and a receiving electrode assembly, and the receiving electrode assembly includes a first annular receiving pole piece 201 and a second annular receiving pole piece 202 arranged concentrically, the first annular reflecting pole piece 101 and the first annular receiving pole piece 201 are directly opposite, and the second annular reflecting pole piece 102 and the second annular receiving pole piece 202 are directly opposite. The excitation electrode assembly includes a plurality of excitation pole pieces 203 uniformly distributed on the stator base 2 along the circumferential direction, the excitation pole pieces 203 are in a fan-shaped structure, and each excitation pole piece 203 is arranged at equal intervals along the circumferential direction of the stator base 2, and each excitation pole piece 203 has the same radial height and the same central angle, the central angle of the induction pole piece 103 is equal to the central angle of the excitation pole piece 203, and the central angle of the interval between two adjacent induction pole pieces 103 is twice the central angle of the interval between two adjacent excitation pole pieces 203.

[0023] The differential sensing electrode assembly and the excitation electrode assembly are both connected to the channel selector. The differential sensing electrode assembly forms a first sensing electrode assembly or a second sensing electrode assembly that is turned on according to different sensing electrodes 103 selected by the channel selector, that is, the channel selector can select sensing electrodes 103 at different positions to be turned on, and sensing electrodes 103 that are turned on in different situations together constitute the first sensing electrode assembly or the second sensing electrode assembly. The excitation electrode assembly forms a first excitation electrode assembly or a second excitation electrode assembly that is turned on according to different excitation electrodes 203 selected by the channel selector, that is, the channel selector can select excitation electrodes 203 at different positions to be turned on, and excitation electrodes 203 that are turned on in different situations together constitute the first excitation electrode assembly or the second excitation electrode assembly. Specifically, the channel selector includes a sensing electrode channel selector and an excitation electrode channel selector. The sensing electrode channel selector is a dual-channel single-pole single-throw switch, and the excitation electrode channel selector is a dual-channel single-pole single-throw switch or a multi-way data selector. As shown in the attached figure Figure 4As shown, all the excitation electrodes 203 are independently connected to a four-to-one data selector, and the four-way input signals of all the data selectors are simultaneously connected to the four-way excitation signals, and the first excitation electrode assembly and the second excitation electrode assembly are determined by the corresponding excitation signals selected by the electrodes. The difference between using a dual-channel single-pole single-throw switch and a data selector is that when a data selector is used, the excitation electrode can output the corresponding excitation signal to determine the excitation electrode group without leads.

[0024] Specifically, the differential sensing electrode assembly and the excitation electrode assembly may adopt an M / 1 pole-pair scheme or an N / N-1 pole-pair scheme.

[0025] Among them, the M / 1 antipodal solution is: In the first excitation electrode assembly, every four adjacent excitation pole pieces 203 form a pole pair, and there are M pole pairs in total, wherein the excitation pole pieces 203 No. 4n1+1 are connected into a group to form an A1 excitation phase, the excitation pole pieces 203 No. 4n1+2 are connected into a group to form a B1 excitation phase, the excitation pole pieces 203 No. 4n1+3 are connected into a group to form a C1 excitation phase, and the excitation pole pieces 203 No. 4n1+4 are connected into a group to form a D1 excitation phase, wherein n1 is all integers from 0 to M-1 in sequence; In the second excitation electrode assembly, all the excitation pole pieces 203 form a counterpole, with a total of 1 counterpole, the 1st, 2nd, ...n2th excitation pole pieces 203 are connected into a group to form an A2 excitation phase, the n2+1st, n2+2nd, ...2n2th excitation pole pieces 203 are connected into a group to form a B2 excitation phase, the 2n2+1st, 2n2+2nd, ...3n2th excitation pole pieces 203 are connected into a group to form a C2 excitation phase, the 3n2+1st, 3n2+2nd, ...4n2th excitation pole pieces 203 are connected into a group to form a D2 excitation phase, wherein n2=M; In the first sensing electrode assembly, every two adjacent sensing electrode pieces 103 form a pair of electrodes, and there are M pairs of electrodes in total. The sensing electrode pieces 103 No. 2n3+1 are connected into a group to form an A1 sensing group, and the sensing electrode pieces 103 No. 2n3+2 are connected into a group to form a B1 sensing group, wherein n3 is all integers from 0 to M-1 in sequence; In the second sensing electrode assembly, all sensing pole pieces 103 form a pair of poles, with a total of 1 pair of poles. The 1st, 2nd, ... n4th sensing pole pieces 103 are connected into a group to form an A2 sensing group, and the n4+1st, n4+2nd, ... 2n4th sensing pole pieces 103 are connected into a group to form a B2 sensing group, where n4=M.

[0026] Among them, the N / N-1 pole solution is: In the first excitation electrode assembly, each adjacent 4n6 excitation electrode pieces 203 form a counter electrode, and there are N counter electrodes in total; The excitation pole pieces 203 of No. n5*4n6+1, n5*4n6+2, ...n5*4n6+n6 are connected as a group to form the A1 excitation phase. The excitation pole pieces 203 of No. n5*4n6+n6+1, n5*4n6+n6+2, ...n5*4n6+2n6 are connected as a group to form the B1 excitation phase. The excitation pole pieces 203 of No. n5*4n6+2n6+1, n5*4n6+2n6+2, ...n5*4n6+3n6 are connected as a group to form the C1 excitation phase. The excitation pole pieces 203 of No. n5*4n6+3n6+1, n5*4n6+3n6+2, ...n5*4n6+4n6 are connected as a group to form the D1 excitation phase, n5 is all integers from 0 to N-1, and n6=N-1; In the second excitation electrode assembly, each adjacent 4n8 excitation electrode pieces 203 form a counter electrode, and there are N-1 counter electrodes in total; Connect the excitation pole pieces 203 No. n7*4n8+1, n7*4n8+2, ... n7*4n8+n8 into a group to form an A2 excitation phase; The excitation pole pieces 203 of No. n7*4n8+n8+1, n7*4n8+n8+2, ...n7*4n8+2n8 are connected as a group to form the B2 excitation phase; The excitation pole pieces 203 of No. n7*4n8+2n8+1, n7*4n8+2n8+2, ...n7*4n8+3n8 are connected as a group to form the C2 excitation phase; The excitation pole pieces 203 of No. n7*4n8+3n8+1, n7*4n8+3n8+2, ...n7*4n8+4n8 are connected as a group to form the D2 excitation phase, n7 is all integers from 0 to N-2, and n8=N; In the first sensing electrode assembly, each adjacent 2n 10 The inductive pole pieces 103 form a pair of poles, and there are N pairs of poles in total; The n9*2n 10 +1, n9*2n 10 +2,... n9*2n 10 +n 10 The induction electrodes 103 are connected into a group to form the A1 induction group. No. n9*2n 10 +n 10 +1, n9*2n 10 +n 10 +2,... n9*2n 10 +n 10 +2n 10The sensing pole pieces 103 are grouped together to form a B1 sensing group; n9 takes all integers from 0 to N-1, n 10 =N-1; In the second sensing electrode assembly, each adjacent 2n 12 The inductive pole pieces 103 form a pair of poles, and there are N-1 pairs of poles in total; The nth 11 *2n 12 +1, n 11 *2n 12 +2, ... n 11 *2n 12 +n 12 The sensing pole pieces 103 are connected into a group to form an A2 sensing group; No.n 11 *2n 12 +n 12 +1, n 11 *2n 12 +n 12 +2, ...n 11 *2n 12 +2n 12 The induction electrodes 103 are connected into a group to form a B2 induction group; 11 Take all integers from 0 to N-2, n 12 =N.

[0027] In this specific embodiment, a system for measuring absolute angular displacement is also provided. Figure 5 As shown, it includes the above-mentioned single-turn absolute time-grid angular displacement sensor with controllable electrode period number, a subtraction circuit, a shaping circuit and an FPGA signal processing system; The signal output terminal of the single-turn absolute time-grid angular displacement sensor is connected to the signal input terminal of the subtraction circuit; The signal output end of the subtraction circuit is connected to the signal input end of the shaping circuit. The subtraction circuit synthesizes the traveling wave signal output by the single-turn absolute time-grid angular displacement sensor into two differential sine wave signals and outputs them to the shaping circuit. The signal output end of the shaping circuit is connected to the input end of the FPGA signal processing system. The shaping circuit shapes the two differential sinusoidal wave signals output by the subtraction circuit into two square wave signals and outputs them to the FPGA signal processing system. The shaping circuit also shapes the same-frequency reference sinusoidal signal into a square wave signal and outputs it to the FPGA signal processing system. The FPGA signal processing system includes a precise angular displacement value calculation module, a coarse angular displacement value calculation module and an absolute angular displacement value calculation module. The precise angular displacement value calculation module is used to obtain a precise angular displacement value according to an output signal of a shaping circuit. The coarse angular displacement value calculation module is used to obtain a coarse angular displacement value according to an output signal of a shaping circuit. The absolute angular displacement value calculation module is used to obtain an absolute angular displacement value according to the precise angular displacement value and the coarse angular displacement value.

[0028] In this specific embodiment, a method for measuring an absolute angular displacement value is also provided. The above-mentioned absolute angular displacement value measurement system is used, and a time-sharing gating method is adopted. A channel selector is used to respectively select the A1 excitation phase, the B1 excitation phase, the C1 excitation phase, the D1 excitation phase, the A2 excitation phase, the B2 excitation phase, the C2 excitation phase, the D2 excitation phase, and the corresponding A1 sensing group, the B1 sensing group, the A2 sensing group, and the B2 sensing group. The method specifically includes the following steps: Step 1) The rotor base 1 and the stator base 2 rotate in parallel with each other, and the first sensing electrode assembly and the first excitation electrode assembly are cut off by a channel selector, and the second sensing electrode assembly and the second excitation electrode assembly are turned on at the same time, and four-way sinusoidal excitation signals of the same frequency and equal amplitude with a phase difference of 90° are applied to the second excitation electrode assembly. Specifically, four-way sinusoidal excitation signals of the same frequency and equal amplitude with a phase difference of 90° are applied to the A2 excitation phase, the B2 excitation phase, the C2 excitation phase, and the D2 excitation phase of the second excitation electrode assembly, respectively, and the sinusoidal excitation signals are transmitted between the second excitation electrode assembly and the second sensing electrode assembly. The coupling electric field generates two sinusoidal traveling wave signals with the same frequency and amplitude and a phase difference of 180° on the A2 induction group and the B2 induction group of the second induction electrode assembly. The two sinusoidal traveling wave signals are respectively reflected to the first annular receiving electrode piece 201 and the second annular receiving electrode piece 202 by the first annular reflecting electrode piece 101 and the second annular reflecting electrode piece 102. The first traveling wave signal is output on the first annular receiving electrode piece 201, and the second traveling wave signal is output on the second annular receiving electrode piece 202. The first traveling wave signal and the second traveling wave signal are synthesized into a first differential sinusoidal traveling wave signal U by a subtraction circuit. o1 , the first differential sinusoidal traveling wave signal U o1 After being shaped into a square wave by the shaping circuit, it is stored in the RAM of the FPGA signal processing system; Step 2) Use the channel selector to quickly cut off the second sensing electrode assembly and the second excitation electrode assembly, and turn on the first sensing electrode assembly and the first excitation electrode assembly, and apply four-way sinusoidal excitation signals of the same frequency and amplitude with a phase difference of 90° as in step 1), specifically, four-way sinusoidal excitation signals of the same frequency and amplitude with a phase difference of 90° are applied to the A1 excitation phase, B1 excitation phase, C1 excitation phase and D1 excitation phase of the first excitation electrode assembly, respectively, and the sinusoidal excitation signals are coupled to the first excitation electrode assembly through the electric field between the first excitation electrode assembly and the first sensing electrode assembly. Two sinusoidal traveling wave signals with the same frequency, equal amplitude and a phase difference of 180° are generated on the A1 sensing group and the B1 sensing group of the electrode assembly. The two sinusoidal traveling wave signals are respectively reflected to the first annular receiving electrode piece 201 and the second annular receiving electrode piece 202 by the first annular reflecting electrode piece 101 and the second annular reflecting electrode piece 102, and a third traveling wave signal is output on the first annular receiving electrode piece 201, and a fourth traveling wave signal is output on the second annular receiving electrode piece 202. The third traveling wave signal and the fourth traveling wave signal are synthesized into a second differential sinusoidal traveling wave signal U by a subtraction circuit. o2 ; Step 3) The second differential sinusoidal traveling wave signal U o2 A reference sinusoidal signal U with the same frequency and fixed phase r After being shaped into a square wave by the shaping circuit, it is sent to the precise angular displacement value calculation module in the FPGA signal processing system for phase comparison. The phase difference after phase comparison is represented by the number of interpolated high-frequency clock pulses, and the precise angular displacement value is obtained after transformation. At the same time, the second differential sinusoidal traveling wave signal U o2 After being shaped into a square wave by the shaping circuit, it is sent to the rough angular displacement value calculation module of the FPGA signal processing system and combined with the first differential sinusoidal traveling wave signal U shaped into a square wave. o1 The phase difference after phase comparison is the same as the phase difference of the reference sinusoidal signal U with the same frequency and fixed phase that is shaped into a square wave. r Then the phase comparison is performed, and the phase difference after the phase comparison is represented by the number of interpolated high-frequency clock pulses, and the rough angular displacement value is obtained after transformation; The absolute angular displacement value calculation module of the FPGA signal processing system calculates the absolute angular displacement value based on the precise angular displacement value and the coarse angular displacement value and then outputs it.

[0029] Compared with the prior art, the present invention aims at the absolute measurement requirements of the existing single-channel incremental time-grating sensor in practical applications, and proposes an absolute time-grating angular displacement sensor and an absolute angular displacement measurement system and method based on a single-circuit electrode period controllable structure. The present invention only uses a single-channel electrode structure, and uses a channel selector to time-select the working state of the electrodes at each position to be turned on or off, so as to realize the absolute displacement value measurement of the time-grating angular displacement sensor. Therefore, this scheme adopts a single-circuit absolute design, and uses differential and reflection structures, which not only realizes the absolute encoding of each position within the entire range, but also the number of electrode periods can be flexibly controlled. Compared with the double-circuit structure, its loop width, circuit cost and decoding and encoding methods are greatly improved, and at the same time, it also improves the adaptability to the industrial use environment and can meet the application requirements of more occasions.

[0030] Embodiment 1: In this specific embodiment, the lower surface of the rotor matrix 1 is parallel to the upper surface of the stator matrix 2, with a gap of 0.5 mm. The stator matrix 2 and the rotor matrix 1 are both made of ceramic as the matrix material, and a layer of iron-nickel alloy is sprayed on the ceramic surface as the electrode pole piece. The upper surface of the stator matrix 2 is provided with a differential receiving electrode assembly and an excitation electrode assembly in sequence from the outer ring to the inner ring. The receiving electrode assembly is composed of a concentric first annular receiving electrode piece 201 and a second annular receiving electrode piece 202 spaced 0.2 mm apart. The inner radius of the first annular receiving electrode piece 201 is 39.5 mm and the outer radius is 41.9 mm. The inner radius of the second annular receiving electrode piece 202 is 42.1 mm and the outer radius is 44.5 mm. The first annular receiving electrode piece 201 serves as the output electrode of the first and third traveling wave signals (i.e., the first and third traveling wave signals can be output under excitation), and the second annular receiving electrode piece 202 serves as the output electrode of the second and fourth traveling wave signals (i.e., the second and fourth traveling wave signals can be output under excitation). The excitation electrode assembly is composed of a circle of fan-shaped annular pole pieces with an inner radius of 28 mm, a radial height of 7 mm, and a center angle of 3.75°, which are arranged at equal intervals along the circumferential direction. The center angle of the interval (i.e., the center angle of the interval between two adjacent fan-shaped annular pole pieces) is 3.75°. There are 48 fan-shaped annular pole pieces in total.

[0031] The lower surface of the rotor base 1 is provided with a differential reflection electrode assembly and a differential induction electrode assembly in sequence from the outer ring to the inner ring. The reflection electrode assembly is opposite to the receiving electrode assembly, and the differential induction electrode assembly is opposite to the excitation electrode assembly. The induction electrode assembly is composed of a circle of identical double sinusoidal pole pieces arranged at equal intervals along the circumferential direction, the center angle of the interval (i.e., the center angle of the interval between two adjacent double sinusoidal pole pieces) is 11.25°, the distance from the center of each double sinusoidal pole piece to the center of the circle (i.e., the radius of the circle where the center of each double sinusoidal pole piece is located) is 31.5mm, the radial height of each double sinusoidal pole piece is 6mm, and the center angle of the opposite circle is 3.75°. There are 24 double sinusoidal pole pieces in total. The shape of the double sinusoidal pole pieces after unfolding along the circumferential direction is a fully closed axisymmetric figure surrounded by two sinusoidal curves with equal amplitude and 180° phase difference in the interval [0, π]. The reflective electrode assembly is composed of a concentric first annular reflective electrode piece 101 and a second annular reflective electrode piece 102 spaced 0.2 mm apart, the inner radius of the first annular reflective electrode piece 101 is 39.5 mm, the outer radius is 41.9 mm, the inner radius of the second annular reflective electrode piece 102 is 42.1 mm, the outer radius is 44.5 mm, the first annular reflective electrode piece 101 is directly opposite to the first annular receiving electrode piece 201, and the second annular reflective electrode piece 102 is directly opposite to the second annular receiving electrode piece 202. In this specific embodiment, the M / 1 pole pair scheme is adopted, the number of pole pairs of the first excitation electrode assembly selected is 12, and each adjacent four excitation pole pieces 203 form a pole pair. Among them, the 4n1+1st excitation pole pieces 203 in the clockwise direction of the circumference are connected into a group through the first excitation signal connection line to form an A1 excitation phase, the 4n1+2nd excitation pole pieces 203 are connected into a group through the second excitation signal connection line to form a B1 excitation phase, the 4n1+3rd excitation pole pieces 203 are connected into a group through the third excitation signal connection line to form a C1 excitation phase, and the 4n1+4th excitation pole pieces 203 are connected into a group through the fourth excitation signal connection line to form a D1 excitation phase, and n1 sequentially takes all integers from 0 to 11. The number of pairs of poles of the selected second excitation electrode assembly is 1, and all excitation pole pieces 203 form one pair of poles. Among them, the 1st, 2nd, ...n2th excitation pole pieces 203 along the clockwise direction of the circumference are connected into a group through the fifth excitation signal connecting line to form an A2 excitation phase, the n2+1st, n2+2nd, ...2n2th excitation pole pieces 203 are connected into a group through the sixth excitation signal connecting line to form a B2 excitation phase, the 2n2+1st, 2n2+2nd, ...3n2th excitation pole pieces 203 are connected into a group through the seventh excitation signal connecting line to form a C2 excitation phase, the 3n2+1st, 3n2+2nd, ...4n2th excitation pole pieces 203 are connected into a group through the eighth excitation signal connecting line to form a D2 excitation phase, and n2=12.The number of pairs of electrodes of the selected first sensing electrode assembly is 12, and each adjacent two sensing electrode pieces 103 form a pair of electrodes. Among them, the 2n3+1 sensing electrode pieces 103 along the circumference clockwise are connected into a group through the first sensing signal connection line to form an A1 sensing group, and the 2n3+2 sensing electrode pieces 103 are connected into a group through the second sensing signal connection line to form a B1 sensing group, and n3 is all integers from 0 to 11 in sequence.

[0032] The number of pairs of electrodes of the selected second sensing electrode assembly is 1, and all sensing electrode pieces 103 form one pair of electrodes. Among them, the 1st, 2nd, ... n4th sensing electrode pieces 103 along the circumference clockwise are connected into a group through the third sensing signal connection line to form an A2 sensing group, and the n4+1st, n4+2nd, ... 2n4th sensing electrode pieces 103 are connected into a group through the fourth sensing signal connection line to form a B2 sensing group, and n4=12.

[0033] Embodiment 2: The difference from Example 1 is that this embodiment adopts an N / N-1 pole pair scheme. The number of pole pairs of the selected first excitation electrode assembly is 4, and every 12 adjacent excitation pole pieces 203 form a pole pair. Among them, the excitation pole pieces 203 No. n5*4n6+1, n5*4n6+2...n5*4n6+n6 along the circumference clockwise are connected into a group through the first excitation signal connection line to form an A1 excitation phase, the excitation pole pieces 203 No. n5*4n6+n6+1, n5*4n6+n6+2...n5*4n6+2n6 along the circumference clockwise are connected into a group to form an A1 excitation phase, the excitation pole pieces 203 No. n5*4n6+n6+1, n5*4n6+n6+2...n5*4n6+2n6 along the circumference clockwise are connected into a group to form an A1 excitation phase, the excitation pole pieces 203 No. n5*4n6+n6+1, n5*4n6+n6+2...n5*4n6+2n6 along the circumference clockwise are connected into a group to form an A1 excitation phase, the excitation pole pieces 203 No. n5*4n6+2 The excitation pole pieces 203 of number n6+1, n5*4n6+2n6+2...n5*4n6+3n6 are connected as a group through the third excitation signal connection line to form a C1 excitation phase, and the excitation pole pieces 203 of number n5*4n6+3n6+1, n5*4n6+3n6+2...n5*4n6+4n6 are connected as a group through the fourth excitation signal connection line to form a D1 excitation phase, and n5 takes all integers from 0 to 3 in sequence, and n6 = 3. The number of pairs of poles of the selected second excitation electrode assembly is 3, and each adjacent 16 excitation pole pieces 203 form a pair of poles. Among them, along the circumference clockwise direction, the n7*4n8+1, n7*4n8+2, ...n7*4n8+n8 excitation pole pieces 203 are connected into a group through the fifth excitation signal connecting line to form an A2 excitation phase, the n7*4n8+n8+1, n7*4n8+n8+2, ...n7*4n8+2n8 excitation pole pieces 203 are connected into a group through the sixth excitation signal connecting line to form a B2 excitation phase, and the n7*4n8+2n8+1, n7*4n8+2n8+2 ...n7*4n8+3n8 excitation pole pieces 203 are connected to form a group through the seventh excitation signal connection line to form a C2 excitation phase, and n7*4n8+3n8+1, n7*4n8+3n8+2, ...n7*4n8+4n8 excitation pole pieces 203 are connected to form a group through the eighth excitation signal connection line to form a D2 excitation phase, n7 is all integers from 0 to 2, and n8=4. The number of pairs of poles of the first sensing electrode assembly selected is 4, and each adjacent 6 sensing pole pieces 103 form a pair of poles. Among them, the n9*2nth pairs of poles along the circumference clockwise direction are connected to form a C2 excitation phase. 10 +1, n9*2n 10 +2,...n9*2n 10 +n 10 The n9*2n sensing electrodes 103 are connected into a group through the first sensing signal connecting line to form an A1 sensing group. 10 +n 10 +1, n9*2n 10 +n 10 +2,...n9*2n 10 +2n 10 The sensing electrodes 103 are connected into a group through the second sensing signal connecting line to form a B1 sensing group, and n9 is all integers from 0 to 3. 10 =3. The number of pairs of electrodes of the selected second sensing electrode assembly is 3, and each of the eight adjacent sensing electrode pieces 103 forms a pair of electrodes. 11 *2n 12 +1, n 11 *2n 12 +2, ...n 11 *2n 12 +n 12 The nth sensing electrodes 103 are connected into a group through the third sensing signal connecting line to form an A2 sensing group. 11 *2n 12 +n 12 +1, n 11 *2n 12 +n 12 +2, ...n 11 *2n 12 +2n 12 The sensing electrodes 103 are connected into a group through the fourth sensing signal connecting line to form a B2 sensing group, n 11 Take all integers from 0 to n 12 =4.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A single-turn absolute time-grating angular displacement sensor, comprising a stator base and a rotor base, characterized in that: The surface of the rotor base body facing the stator base body is provided with an induction electrode assembly and a reflection electrode assembly, the differential induction electrode assembly includes a plurality of induction pole pieces uniformly distributed on the rotor base body along the circumferential direction, the surface of the stator base body facing the rotor base body is provided with an excitation electrode assembly and a receiving electrode assembly, the excitation electrode assembly includes a plurality of excitation pole pieces uniformly distributed on the stator base body along the circumferential direction, the differential induction electrode assembly and the excitation electrode assembly are both connected to a channel selector, the differential induction electrode assembly forms a conductive first induction electrode assembly or a second induction electrode assembly according to different induction pole pieces selected by the channel selector, and the excitation electrode assembly forms a conductive first excitation electrode assembly or a second excitation electrode assembly according to different excitation pole pieces selected by the channel selector.

2. The single-turn absolute time-grating angular displacement sensor according to claim 1, characterized in that: The excitation pole pieces are in a fan-shaped ring structure, and the excitation pole pieces are arranged at equal intervals along the circumferential direction of the stator substrate, and the radial heights of the excitation pole pieces are the same, and the central angles are equal; The induction pole pieces are of a double sinusoidal structure, and the induction pole pieces are arranged at equal intervals along the circumferential direction of the rotor base, and the radial heights of the induction pole pieces are the same, and the central angles are equal; The central angle of the circle opposite to the sensing pole piece is equal to the central angle of the circle opposite to the exciting pole piece, and the central angle of the circle between two adjacent sensing pole pieces is twice the central angle of the circle between two adjacent exciting pole pieces.

3. The single-turn absolute time-grating angular displacement sensor according to claim 2, characterized in that: In the first excitation electrode assembly, every four adjacent excitation pole pieces form a pole pair, and there are M pole pairs in total, wherein the excitation pole pieces No. 4n1+1 are connected into a group to form an A1 excitation phase, the excitation pole pieces No. 4n1+2 are connected into a group to form a B1 excitation phase, the excitation pole pieces No. 4n1+3 are connected into a group to form a C1 excitation phase, and the excitation pole pieces No. 4n1+4 are connected into a group to form a D1 excitation phase, wherein n1 is all integers from 0 to M-1 in sequence; In the second excitation electrode assembly, all excitation electrode pieces form a pair of electrodes, and there is a total of one pair of electrodes. The excitation pole pieces No. n2+1, n2+2, ... 2n2 are connected as a group to form the A2 excitation phase, the excitation pole pieces No. n2+1, 2n2+2, ... 3n2 are connected as a group to form the C2 excitation phase, the excitation pole pieces No. 3n2+1, 3n2+2, ... 4n2 are connected as a group to form the D2 excitation phase, where n2=M; In the first sensing electrode assembly, every two adjacent sensing electrode pieces form a pair of electrodes, and there are M pairs of electrodes in total. The sensing electrode pieces No. 2n3+1 are connected into a group to form an A1 sensing group, and the sensing electrode pieces No. 2n3+2 are connected into a group to form a B1 sensing group, wherein n3 is all integers from 0 to M-1 in sequence; In the second sensing electrode assembly, all sensing electrode pieces form a pair of electrodes, and there is a total of one pair of electrodes. The induction electrodes No. n4+1, n4+2, ... 2n4 are connected into a group to form an A2 induction group, and the induction electrodes No. n4+1, n4+2, ... 2n4 are connected into a group to form a B2 induction group, wherein n4=M.

4. The single-turn absolute time-grating angular displacement sensor according to claim 2, characterized in that: In the first excitation electrode assembly, each adjacent 4n6 excitation electrode pieces form a counter electrode, and there are N counter electrodes in total; The excitation poles n5*4n6+1, n5*4n6+2, ...n5*4n6+n6 are connected as a group to form the A1 excitation phase. The excitation poles n5*4n6+n6+1, n5*4n6+n6+2, ...n5*4n6+2n6 are connected as a group to form the B1 excitation phase. The excitation poles n5*4n6+2n6+1, n5*4n6+2n6+2, ...n5*4n6+3n6 are connected as a group to form the C1 excitation phase. The excitation pole pieces n5*4n6+3n6+1, n5*4n6+3n6+2, ...n5*4n6+4n6 are connected as a group to form the D1 excitation phase, n5 is all integers from 0 to N-1, n6=N-1; In the second excitation electrode assembly, each adjacent 4n8 excitation electrode pieces form a pair of electrodes, and there are N-1 pairs of electrodes in total; Connect the excitation pole pieces No. n7*4n8+1, n7*4n8+2, ...n7*4n8+n8 into a group to form the A2 excitation phase; The excitation pole pieces No. n7*4n8+n8+1, n7*4n8+n8+2, ...n7*4n8+2n8 are connected as a group to form the B2 excitation phase; The excitation pole pieces n7*4n8+2n8+1, n7*4n8+2n8+2, ...n7*4n8+3n8 are connected as a group to form the C2 excitation phase; The excitation pole pieces n7*4n8+3n8+1, n7*4n8+3n8+2, ...n7*4n8+4n8 are connected as a group to form the D2 excitation phase, n7 is all integers from 0 to N-2, n8=N; In the first sensing electrode assembly, each adjacent 2n 10 The inductive pole pieces form a pair of poles, and there are N pairs of poles in total; The n9*2n 10 +1, n9*2n 10 +2,... n9*2n 10 +n 10 The induction electrodes are connected into a group to form the A1 induction group. No. n9*2n 10 +n 10 +1, n9*2n 10 +n 10 +2,... n9*2n 10 +n 10 +2n 10 The sensing electrodes are grouped together to form the B1 sensing group; n9 takes all integers from 0 to N-1, n 10 =N-1; In the second sensing electrode assembly, each adjacent 2n 12 The inductive pole pieces form a pair of poles, and there are N-1 pairs of poles in total; The nth 11 *2n 12 +1, n 11 *2n 12 +2, ... n 11 *2n 12 +n 12 The sensing electrodes are connected into a group to form the A2 sensing group; No.n 11 *2n 12 +n 12 +1, n 11 *2n 12 +n 12 +2, ...n 11 *2n 12 +2n 12 The sensing electrodes are connected into a group to form a B2 sensing group; 11 Take all integers from 0 to N-2, n 12 =N.

5. The single-turn absolute time-grating angular displacement sensor according to claim 3 or 4, characterized in that: The reflecting electrode assembly comprises a first annular reflecting pole piece and a second annular reflecting pole piece which are arranged concentrically, and the receiving electrode assembly comprises a first annular receiving pole piece and a second annular receiving pole piece which are arranged concentrically, the first annular reflecting pole piece and the first annular receiving pole piece are directly opposite to each other, and the second annular reflecting pole piece and the second annular receiving pole piece are directly opposite to each other; The first annular reflective pole piece is connected to the A1 sensing group and the A2 sensing group, and the second annular reflective pole piece is connected to the B1 sensing group and the B2 sensing group.

6. The single-turn absolute time-grating angular displacement sensor according to claim 5, characterized in that: The channel selector includes a sensing electrode channel selector and an excitation electrode channel selector. The sensing electrode channel selector is a dual-channel single-pole single-throw switch, and the excitation electrode channel selector is a dual-channel single-pole single-throw switch or a multi-way data selector.

7. An absolute angular displacement value measurement system, characterized in that: It comprises a single-turn absolute time-grid angular displacement sensor with controllable electrode period number as claimed in claim 6, a subtraction circuit, a shaping circuit and an FPGA signal processing system; The signal output end of the single-turn absolute time-grid angular displacement sensor is connected to the signal input end of the subtraction circuit; The signal output end of the subtraction circuit is connected to the signal input end of the shaping circuit, and the subtraction circuit synthesizes the traveling wave signal output by the single-turn absolute time-grid angular displacement sensor into two differential sine wave signals and outputs them to the shaping circuit; The signal output end of the shaping circuit is connected to the input end of the FPGA signal processing system, and the shaping circuit shapes the two differential sinusoidal wave signals output by the subtraction circuit into two square wave signals and outputs them to the FPGA signal processing system, and the shaping circuit also transforms the same-frequency reference sinusoidal signal into a square wave signal and outputs it to the FPGA signal processing system; The FPGA signal processing system includes a precise angular displacement value calculation module, a coarse angular displacement value calculation module and an absolute angular displacement value calculation module. The precise angular displacement value calculation module is used to obtain a precise angular displacement value according to the output signal of the shaping circuit, the coarse angular displacement value calculation module is used to obtain a coarse angular displacement value according to the output signal of the shaping circuit, and the absolute angular displacement value calculation module is used to obtain an absolute angular displacement value according to the precise angular displacement value and the coarse angular displacement value.

8. A method for measuring absolute angular displacement, characterized in that: The absolute angular displacement value measuring system as claimed in claim 7 comprises the following steps: Step 1) The rotor base and the stator base rotate relatively parallel to each other, the channel selector is used to cut off the first sensing electrode assembly and the first excitation electrode assembly, and the second sensing electrode assembly and the second excitation electrode assembly are turned on at the same time, and four sinusoidal excitation signals of the same frequency and amplitude with a phase difference of 90° are applied to the second excitation electrode assembly. The sinusoidal excitation signals are coupled to the electric field between the second excitation electrode assembly and the second sensing electrode assembly to generate two sinusoidal traveling wave signals of the same frequency and amplitude with a phase difference of 180° on the second sensing electrode assembly. The two sinusoidal traveling wave signals are reflected to the receiving electrode assembly by the reflecting electrode assembly, and the first traveling wave signal and the second traveling wave signal are output on the receiving electrode assembly. The first traveling wave signal and the second traveling wave signal are synthesized into a first differential sinusoidal traveling wave signal U by a subtraction circuit. o1 , the first differential sinusoidal traveling wave signal U o1 After being shaped into a square wave by a shaping circuit, it is stored in the RAM of the FPGA signal processing system; Step 2) using the channel selector to quickly cut off the second sensing electrode assembly and the second excitation electrode assembly, and turn on the first sensing electrode assembly and the first excitation electrode assembly, and the four-way sinusoidal excitation signals with the same frequency and amplitude and the same phase difference of 90° as in step 1) are sequentially transmitted, and the sinusoidal excitation signals are coupled to the electric field between the first excitation electrode assembly and the first sensing electrode assembly to generate two sinusoidal traveling wave signals with the same frequency and amplitude and a phase difference of 180° on the first sensing electrode assembly, and the two sinusoidal traveling wave signals are reflected to the receiving electrode assembly through the reflecting electrode assembly, and the third traveling wave signal and the fourth traveling wave signal are output on the receiving electrode assembly, and the third traveling wave signal and the fourth traveling wave signal are synthesized into the second differential sinusoidal traveling wave signal U through the subtraction circuit. o2 ; Step 3) The second differential sinusoidal traveling wave signal U o2 A reference sinusoidal signal U with the same frequency and fixed phase r After being shaped into a square wave by a shaping circuit, it is sent to the precise angular displacement value in the FPGA signal processing system for calculation to obtain the precise angular displacement value; At the same time, the second differential sinusoidal traveling wave signal U o2 After being shaped into a square wave by the shaping circuit, the first differential sinusoidal traveling wave signal U shaped into a square wave o1 The rough angular displacement value is sent to the rough angular displacement value calculation module of the FPGA signal processing system to calculate the rough angular displacement value; The absolute angular displacement value calculation module of the FPGA signal processing system calculates the absolute angular displacement value based on the precise angular displacement value and the coarse angular displacement value and then outputs it.

9. The absolute angular displacement value measuring method according to claim 8, characterized in that: In step 1), four sinusoidal excitation signals of the same frequency and amplitude with a phase difference of 90° are applied to the A2 excitation phase, B2 excitation phase, C2 excitation phase and D2 excitation phase of the second excitation electrode assembly respectively. The sinusoidal excitation signals are coupled to the electric field between the second excitation electrode assembly and the second sensing electrode assembly to generate two sinusoidal traveling wave signals of the same frequency and amplitude with a phase difference of 180° on the A2 sensing group and the B2 sensing group of the second sensing electrode assembly respectively. The two sinusoidal traveling wave signals are reflected to the first annular receiving electrode piece and the second annular receiving electrode piece respectively by the first annular reflecting electrode piece and the second annular reflecting electrode piece, and the first traveling wave signal is output on the first annular receiving electrode piece, and the second traveling wave signal is output on the second annular receiving electrode piece. The first traveling wave signal and the second traveling wave signal are synthesized into a first differential sinusoidal traveling wave signal U by a subtraction circuit. o1 , the first differential sinusoidal traveling wave signal U o1 After being shaped into a square wave by a shaping circuit, it is stored in the RAM of the FPGA signal processing system; In step 2), four sinusoidal excitation signals of the same frequency and amplitude with a phase difference of 90° are applied to the A1 excitation phase, B1 excitation phase, C1 excitation phase and D1 excitation phase of the first excitation electrode assembly respectively. The sinusoidal excitation signals are coupled to the electric field between the first excitation electrode assembly and the first sensing electrode assembly to generate two sinusoidal traveling wave signals of the same frequency and amplitude with a phase difference of 180° on the A1 sensing group and the B1 sensing group of the first sensing electrode assembly respectively. The two sinusoidal traveling wave signals are reflected to the first annular receiving electrode piece and the second annular receiving electrode piece respectively by the first annular reflecting electrode piece and the second annular reflecting electrode piece, and a third traveling wave signal is output on the first annular receiving electrode piece, and a fourth traveling wave signal is output on the second annular receiving electrode piece. The third traveling wave signal and the fourth traveling wave signal are synthesized into a second differential sinusoidal traveling wave signal U by a subtraction circuit. o2 .

10. The absolute angular displacement value measuring method according to claim 8, characterized in that: In step 3), the second differential sinusoidal traveling wave signal U o2 A reference sinusoidal signal U with the same frequency and fixed phase r After being shaped into a square wave by the shaping circuit, it is sent to the precise angular displacement value calculation module in the FPGA signal processing system for phase comparison. The phase difference after phase comparison is represented by the number of interpolated high-frequency clock pulses, and the precise angular displacement value is obtained after transformation. At the same time, the second differential sinusoidal traveling wave signal U o2 After being shaped into a square wave by the shaping circuit, it is sent to the rough angular displacement value calculation module of the FPGA signal processing system and combined with the first differential sinusoidal traveling wave signal U shaped into a square wave. o1 The phase difference after phase comparison is the same as the phase difference of the reference sinusoidal signal U with the same frequency and fixed phase that is shaped into a square wave. r Then the phase comparison is performed, and the phase difference after the phase comparison is represented by the number of interpolated high-frequency clock pulses, and the rough angular displacement value is obtained after transformation; The absolute angular displacement value calculation module of the FPGA signal processing system calculates the absolute angular displacement value based on the precise angular displacement value and the coarse angular displacement value and then outputs it.

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