Eccentricity error compensation method for multi-pole magnetoelectric encoder

Abstract

The invention belongs to the technical field of special elements and electromechanical components, and discloses an eccentric error compensation method for a multi-pole magnetoelectric encoder. According to the multi-pole magnetoelectric encoder eccentric error compensation method, a hardware scheme of two resolving chips based on the Hall effect is adopted, the space position angle difference of the two chips is 180 degrees, one chip is a main resolving chip and used for resolving current rotation position information, and the other chip is a compensation resolving chip and used for compensating eccentric errors. And then interval mapping processing is carried out on angle output of the main resolving chip and the compensation resolving chip, and the averaged angle on the premise of the welding error of the two chips is used as the final angle to be output. According to the method, the two resolving chips are placed at the symmetrical positions in the space, the eccentricity error during installation is effectively measured, and a hardware basis is provided for software to process the eccentricity error.

Description

Technical Field

[0001] The invention belongs to the technical field of special components and electromechanical components, and in particular to an eccentric error compensation method for a multi-pole magnetoelectric encoder. Background Art

[0002] Multi-pole magnetoelectric encoders are expected to replace rotary transformers and photoelectric encoders in harsh environments due to their small size, high reliability and low cost, and have become a trend in the future development of angle measurement components. Magnetoelectric encoders mainly use the Hall effect to decode the sine-cosine magnetized magnetic ring through the Hall element to obtain the current rotation position information.

[0003] The multi-pole magnetoelectric encoder is mainly composed of a circuit board, a magnetic ring and structural parts, among which the Hall solution chip and the magnetic ring in the circuit board are the core components. According to the product situation of the existing magnetoelectric encoder, the most widely used structure is: the circuit board of the multi-pole magnetoelectric encoder is used as the stator, and the magnetic ring is used as the rotor, and the two are split structures without bearing support. Generally, this type of split magnetoelectric encoder needs to be recalibrated after installation according to certain requirements when in use to ensure the angle measurement accuracy and normal operation of the magnetoelectric encoder. In addition to the need to put forward certain requirements for the coaxiality of the installation and the gap between the stator and the rotor when applying the magnetoelectric encoder in various systems, it is also necessary to recalibrate it after each reinstallation. Otherwise, the performance of the magnetoelectric encoder will be greatly discounted. First, the angle measurement accuracy will decrease, and second, the probability of decoding errors will increase, which will seriously affect the use of the magnetoelectric encoder. However, for large-scale assembly and use scenarios, the recalibration work that must be performed after secondary or multiple installations greatly increases the workload and will extend the assembly and debugging time.

[0004] Therefore, there is an urgent need for a multi-pole magnetoelectric encoder eccentricity error compensation method. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for compensating eccentricity errors of a multi-pole magnetoelectric encoder.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A method for compensating eccentricity error of a multi-pole magnetoelectric encoder, wherein the method adopts a hardware solution of two Hall effect-based solution chips, the spatial position angles of the two chips differ by 180°, one of which is a main solution chip for solving current rotation position information, and the other is a compensation solution chip for compensating eccentricity error;

[0008] Then the angle outputs of the main solver chip and the compensation solver chip are interval mapped, and the angle after average processing under the premise of the welding error of the two chips is output as the final angle.

[0009] Further, the following steps are included:

[0010] Step 1, inputting the two data of the output angle θ1 of the main solution chip and the output angle θ2 of the compensation solution chip into the processing chip;

[0011] Step 2: Map the compensation angle θ2 output by the compensation solution chip to the output angle domain of the main solution chip. It can be concluded from the 180° difference in the spatial positions of the two chips that the angle θ′1 after θ2 mapping is θ2-180°.

[0012] Step 3: Since errors are inevitable in the actual welding process, the premise that the spatial position difference between the main solver chip and the compensation solver chip is 180° may not be achieved. In order to eliminate the influence of welding errors, this step discriminates the spatial position by using the compensation angle θ′1 mapped to the main angle domain and the output angle θ1 of the main solver chip. The specific discrimination conditions are:

[0013] θ1-θ'1>180°;

[0014] When the judgment condition is met, the average processing is performed. When the judgment condition is not met, the compensation angle θ2 output by the compensation solution chip is converted. The conversion processing formula is:

[0015] θ'1=180°-θ2;

[0016] Then, the output angle θ1 of the main solver chip and the output angle mapping angle θ′1 of the compensation solver chip are averaged to obtain the output angle θ, which is:

[0017] θ=(θ′1+θ1) / 2;

[0018] Step 4: Determine whether the output angle θ after averaging processing exceeds the range. The determination condition is θ>360° or θ<0°. If it exceeds the range, it is output after normalization processing. The specific normalization processing process is:

[0019] When θ>360°, θ=θ-360°;

[0020] When θ<0°, θ=θ+360°, otherwise it is output directly.

[0021] Furthermore, the models of the solver chip and the compensation solver chip are both TMR3109.

[0022] The positive effects of the present invention are:

[0023] 1. The method of the present invention effectively measures the eccentricity error during installation by placing two solving chips at symmetrical positions in space (if the eccentricity error in multiple directions is to be avoided, the solving chips can be placed at multiple symmetrical positions or asymmetrical positions), providing a hardware basis for software to process the eccentricity error.

[0024] 2. The method of the present invention adopts the angle output average processing method. By analyzing the chip placement position, two discriminant conditions for solving the chip welding error are introduced at the same time to avoid the judgment error in the angle calculation process, and finally the influence of the eccentricity error can be effectively eliminated.

[0025] 3. In terms of hardware, the method of the present invention adopts a two-chip solution, one is a main chip, and the other is a compensation chip. The installation positions of the two chips differ by 180° in space; in terms of software, the angle output of the two chips is averaged as the final angle output. The method of the present invention enhances the anti-eccentricity capability of the magnetoelectric encoder, omits the steps of repeated calibration after installation, and can also avoid the influence of eccentricity error caused by the stator and rotor offset of the magnetoelectric encoder in long-term use. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a typical multi-pole magnetoelectric encoder structure connection diagram in the prior art;

[0027] Figure 2 It is a schematic diagram of the spatial positions of the main solution chip, the compensation solution chip and the magnetoelectric encoder rotor of the present invention;

[0028] Figure 3 It is a schematic diagram of solving the axial eccentricity of the magnetoelectric encoder of the present invention;

[0029] Figure 4 A schematic diagram of the axial eccentricity angle error of the magnetoelectric encoder of the present invention;

[0030] Figure 5 A schematic diagram of the axial eccentricity angle error waveform of the magnetoelectric encoder of the present invention;

[0031] Figure 6 It is a schematic diagram of the axial eccentricity angle error of the magnetoelectric encoder with a compensation chip of the present invention;

[0032] Figure 7 It is a schematic diagram of a flow chart of the eccentricity error compensation method of the present invention;

[0033] Figure 8 This is a measurement diagram of the angle measurement accuracy of the magnetoelectric encoder under different eccentricities without adopting the method of the present invention;

[0034] Fig. 9 This is a measurement diagram of the angle measurement accuracy of the magnetoelectric encoder under different eccentricities using the method of the present invention; DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below in conjunction with specific examples. The following examples are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0036] The raw materials used in the present invention, unless otherwise specified, are conventional commercial products, the methods used in the present invention, unless otherwise specified, are conventional methods in the art, and the quality of each substance used in the present invention is conventional quality. The structures, connection relationships, etc. not described in detail in the present invention can be understood as conventional technical means in the art.

[0037] In terms of hardware, the present invention adopts a hardware solution of two Hall effect-based solution chips, the two chips have a spatial angle difference of 180°, one of which is a main solution chip for solving the current rotation position information, and the other is a compensation solution chip for compensating for eccentricity error; in terms of software, the angle outputs of the main solution chip and the compensation solution chip are interval mapped, and the average processed angle under the premise of considering the welding error of the two chips is output as the final angle.

[0038] The hardware scheme diagram of the multi-pole magnetoelectric encoder eccentricity error compensation method of the present invention is as follows: Figure 1 As shown, a hardware solution is adopted in which two chips are spatially symmetrically arranged, one solving chip (as the main solving chip, reflecting the real angle), and the other solving chip is used as a compensation solving chip to compensate for the eccentricity error.

[0039] The two chips are installed on the stator of the magnetoelectric encoder, and the angles of the two chips are 180° apart in space. The schematic diagram of the spatial position of the chip and the rotor is as follows: Figure 2 As shown;

[0040] First, the angle error caused by the eccentricity of the magnetoelectric encoder is explained. The solver chip and the magnetic ring containing the magnetic field information are coaxially installed. Theoretically, the radial distance between the magnetic field sensing position of the solver chip and the magnetic pole center of the magnetic ring is zero, and the axial distance is kept at a certain distance (0.35mm~0.55mm). The radial distance between the two is the eccentricity error of the magnetoelectric encoder. The schematic diagram of the X-axis eccentricity of the solver chip is as follows: Figure 2 The schematic diagram of the X-axis eccentricity angle error is shown in Figure 3, and the X-axis error waveform is shown in Figure 4. Figure 4 If the magnetic encoder has deviation in any radial direction during installation, such as Figure 3 As shown, it is considered that the magnetoelectric encoder is eccentric. At this time, if a resolution chip is used, such as Figure 4As shown in the figure, after one rotation of the chip, the chip output angle will be ahead of or behind the real angle in the interval with the deviation direction and the position that is an integer multiple of 90° away from the deviation direction as the dividing point.

[0041] Since the solver chip uses the magnetic field information of the X-axis and Y-axis induction magnetic ring, that is, the magnetic field direction is represented by the solver chip with sine and cosine signals that change with the magnetic field direction and converges with the orthogonal phase-locked loop to determine the final angle output, when there is an eccentricity error, the solver chip output angle error Δθ can be expressed as:

[0042] Δθ=B α cosθ'-B β sinθ'

[0043] Where: θ'—the output angle of the solution chip, Δθ—the output angle error of the solution chip, B α —Solve the chip sensing sinusoidal signal, B β —Solve the chip sensing cosine signal; where, B is the magnetic field strength induced by the chip.

[0044] It can be further concluded that:

[0045] Δθ=Bsinθcosθ'-Bcosθsinθ'=Bsin(θ-θ')

[0046] Where θ is the actual direction of the magnetic field.

[0047] Therefore, when there is an eccentricity error, the specific waveform of the chip output angle relative to the actual magnetic field direction is calculated as follows Figure 5 shown.

[0048] To eliminate the eccentricity error, Figure 1 In the hardware solution shown, one chip is used as the main solution chip, and the other chip is used as the compensation solution chip. According to the theoretical analysis that the positions of the two chips are strictly 180° apart, each time the installation conditions are different, the angle output errors reflected by the two chips are exactly opposite, such as Figure 6 As shown in the figure, averaging the angle outputs of the two chips can significantly eliminate the eccentricity error and enhance the anti-eccentricity capability of the magnetoelectric encoder.

[0049] In the present invention, the solver chip and the compensation solver chip can be any known chip in the prior art, for example, TMR3109.

[0050] A method for compensating eccentricity error of a multi-pole magnetoelectric encoder, such as Figure 7 As shown, the following steps are included:

[0051] Step 1, input the two data of the output angle θ1 of the main solution chip and the output angle θ2 of the compensation solution chip into a processing chip, such as an MCU processing chip such as ARM, DSP, etc.;

[0052] Step 2: Map the compensation angle θ2 output by the compensation solution chip to the output angle domain of the main solution chip. As the spatial position difference between the two chips is 180°, the angle θ′1 after θ2 mapping is θ2-180°.

[0053] Step 3: Due to the inevitable errors in the actual welding process, the premise that the spatial position difference between the main solution chip and the compensation solution chip is 180° may not be achieved. In order to eliminate the influence of welding errors, this step can be used to distinguish the spatial position by using the compensation angle θ′1 mapped to the main angle domain and the output angle θ1 of the main solution chip. The specific judgment condition is θ1-θ'1>180°. When the judgment condition is met, the average processing is performed. When the judgment condition is not met, the compensation angle θ2 output by the compensation solution chip is converted. The conversion processing formula is θ'1=180°-θ2.

[0054] Then, the output angle θ1 of the main solution chip and the output angle mapping angle θ′1 of the compensation solution chip are averaged to obtain the output angle θ, and the formula is θ=(θ′1+θ1) / 2;

[0055] Step 4: Determine whether the output angle θ after averaging processing exceeds the range. The determination condition is θ>360° or θ<0°. If it exceeds the range, it is output after normalization processing. The specific normalization processing process is: when θ>360°, θ=θ-360°; when θ<0°, θ=θ+360°. Otherwise, it is directly output.

[0056] The relevant detection of the method of the present invention is as follows:

[0057] The present invention was experimentally tested on a turntable with an angle measurement accuracy of 1 arc second, verifying the effectiveness of the method of the present invention. Figure 8 and Fig. 9 As shown: when the eccentricity error compensation method is not adopted, the angular measurement accuracy without eccentricity is about ±0.018°, and the angular measurement accuracy with an eccentricity of 50μm is ±0.12°, and the angular measurement accuracy is significantly reduced; when the eccentricity error compensation method is adopted, the angular measurement accuracy without eccentricity is ±0.017°, which is close to the case when the eccentricity error compensation method is not adopted. When the eccentricity gradually increases from 10μm to 100μm, the worst angular measurement accuracy is ±0.02°, which is not significantly reduced.

[0058] Although the embodiments of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments.

Claims

1. A method for compensating eccentricity error of a multi-pole magnetoelectric encoder, characterized in that: The method adopts a hardware solution of two Hall effect-based solution chips, the spatial position angles of the two chips differ by 180°, one of which is a main solution chip for solving the current rotation position information, and the other is a compensation solution chip for compensating for eccentricity error; Then the angle outputs of the main solver chip and the compensation solver chip are interval mapped, and the average angle processed under the premise of considering the welding error of the two chips is output as the final angle.

2. The method for compensating eccentricity error of a multi-pole magnetoelectric encoder according to claim 1, characterized in that: The steps include: Step 1, inputting the two data of the output angle θ1 of the main solution chip and the output angle θ2 of the compensation solution chip into the processing chip; Step 2: Map the compensation angle θ2 output by the compensation solution chip to the output angle domain of the main solution chip. It can be concluded from the 180° difference in the spatial positions of the two chips that the angle θ′1 after θ2 mapping is θ2-180°. Step 3: Since errors are inevitable in the actual welding process, the premise that the spatial position difference between the main solver chip and the compensation solver chip is 180° may not be achieved. In order to eliminate the influence of welding errors, this step discriminates the spatial position by using the compensation angle θ′1 mapped to the main angle domain and the output angle θ1 of the main solver chip. The specific discrimination condition is θ1-θ′1>180°; When the judgment condition is met, the average processing is performed. When the judgment condition is not met, the compensation angle θ2 output by the compensation solution chip is converted. The conversion processing formula is θ′1=180°-θ2; Then, the output angle θ1 of the main solution chip and the output angle mapping angle θ′1 of the compensation solution chip are averaged to obtain the output angle θ, and the formula is θ=(θ1+θ1) / 2; Step 4: Determine whether the output angle θ after averaging processing exceeds the range. The determination condition is θ>360° or θ<0°. If it exceeds the range, it is output after normalization processing. The specific normalization processing process is: When θ>360°, θ=θ-360°; When θ<0°, θ=θ+360°, otherwise it is directly output.

3. The eccentricity error compensation method of a multi-pole magnetoelectric encoder according to claim 1 or 2, characterized in that: The model of the solving chip and the compensation solving chip are both TMR3109.

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