KR100478978B1 - Apparatus for resolution of angular position using hall-ic and method thereof - Google Patents

Abstract

The present invention eliminates the negative influences on the accuracy of the implementation and measures the rotation angle using the Hall IC for the high resolution of the absolute angle position sensor and the position correction using the Hall IC without using high precision machine operation or parts. An apparatus and a method thereof are provided. The present invention, the main operation processing unit for receiving the analog sine, cosine wave output from the Hall IC, and finally outputs the code corresponding to the absolute angle through a series of signal processing process, and measure the characteristic values unique to each angle measuring device in advance In the rotation angle measuring apparatus using a Hall IC including a correction processing unit for calculating a LUT (look-up table) for correction in actual operation, the main operation processing unit is output from the Hall IC as the rotation axis rotates An A / D conversion block for converting an analog sine and cosine wave signal into a corresponding digital code; The offset adjustment is performed so that the intermediate value of the sine and cosine output values converted from the A / D conversion block to the digital code is the origin, and is suitable to prevent saturation caused by the mismatch of the magnitude of the sine and cosine position sensor nominal output voltage. An offset and gain adjustment block for performing tuning by multiplying the scale factor; Normalizing block to remove the effect of the drift gain value according to the temperature change of the permanent magnet; An arc sine LUT control logic block for converting sine and cosine codes into appropriate position angle codes using a look up table (LUT) consisting of output values for addresses and location codes; And an absolute angle code calculation block that performs absolute angle position code calculation for a 360 degree rotation, wherein the correction processing unit receives and records an angle code simultaneously from an absolute angle sensor using a standard encoder mounted on a rotating shaft and a hall IC. ; An angular position code error calculator for which normalized error data is calculated; And a correction LUT data calculator that receives the output data of the angular position code error calculator and the sine and cosine absolute angle position codes together and calculates a correction LUT for removing an error caused by a mechanical assembly tolerance.

Description

Apparatus for resolution of angular position using Hall-IC and Method Thereof}

The present invention relates to a rotation angle measuring device and a method of using the Hall IC in a wide range of industries, such as servo motor control, and more particularly, to implement a high resolution and position correction of an absolute angle position sensor using the Hall IC. The present invention relates to a rotation angle measuring device using a Hall IC and a method thereof.

The most commonly used sensors to measure the rotation angle are optical encoders and are classified into incremental and absolute types. The optical encoder basically consists of a light source for transmitting light, a rotating disk with a slit, and a light receiving element. The optical encoder has a structure that obtains a pulse output proportional to the rotation angle as the disk rotates.

Incremental encoder generates square wave of A phase and B phase (90 degree phase difference with A phase) according to the rotation angle, and the number of pulses proportional to the rotated angle is obtained instead of the absolute value of the rotation position. The angle can be measured cumulatively. However, there is a disadvantage that the current position information is not known until the Z phase pulse (image signal) generated once per revolution is recognized. Incremental encoders are simple in structure and relatively inexpensive.

The absolute encoder has the same basic configuration as the incremental type, but the slit patterns of the rotating disks are arranged concentrically in binary code strings. Absolute encoder detects absolute angular position, so there is no accumulation of error due to noise, and it can always detect accurate current position when power is turned on. Instead, higher resolution (increasing the number of bits) increases the number of output signal lines, making it difficult to miniaturize and somewhat expensive in structure.

While the optical encoder converts the rotation angle information into a digital quantity, the resolver using an inductor type sensor generates an analog output signal. The structure of the resolver is similar to that of a motor, especially with excellent environmental resistance. However, it has a complex mechanical electrical structure, such as several windings and iron cores, and requires a precise power supply that supports mutually perpendicular high frequency AC voltage outputs. In addition, these sensors are very expensive and their applications are very limited.

Compared to the rotation angle sensors mentioned above, the Hall IC uses the simplest mechatronic structure. That is, it consists only of a permanent circuit mounted on a rotating shaft and a simple circuit section equipped with a hall IC. This is because state-of-the-art Hall ICs already have built-in supply and output voltage offset stabilization circuits. The principle of operation is that the magnetic field changes as the permanent magnet mounted on the rotating shaft rotates. The sensor changes in the Hall IC to measure the change of the magnetic field and output the corresponding analog sine and cosine wave. By properly calculating this signal, it is easy to find the Hall IC output voltage value and the corresponding angle value per revolution in a linear relationship. In this way, an absolute angle sensor can be manufactured at much lower cost than an incremental encoder, greatly reducing the overall system manufacturing cost. In addition, it has advantages such as durability due to non-contact method, freedom of design due to clearance of permanent magnet and Hall IC, ease of repair due to simple structure, and environmental resistance to shock, vibration and dust. However, this angle measurement method has some limitations to increase the accuracy of the measurement angle due to mechanical assembly tolerances and the effects of drift on the temperature of the permanent magnetic flux density.

In other words, if the angle position sensor using Hall IC is implemented in an ideal state, that is, the permanent magnet and the Hall IC sensor part are perfectly vertical and two Hall sensors positioned at 90 degrees to each other are completely vertical. If the permanent magnets attached to the axis of rotation are perfectly circular, the desired resolution can be increased to 11 bits by implementing perfect sine and cosine waves per unit vector for the angle at which the Hall IC output voltage is measured. However, in reality, the output signal of the angle position sensor using Hall IC is different from the ideal sine and cosine waveforms, which is caused by mechanical assembly tolerance, error of electromagnetic parameters, and rounding error in A / D conversion.

These factors are the obstacles to the high-resolution implementation of the measurement angle directly, and there is a problem that product cost increases by using high precision machine operation or parts to solve this problem.

Accordingly, the present invention has been made to solve the above-mentioned conventional problems, and eliminates the factors that negatively affect the precision implementation, and uses the absolute IC position sensor without the use of high precision machine operation or parts. An object of the present invention is to provide a rotation angle measuring apparatus and method using a Hall IC for high resolution implementation and position correction.

The rotation angle measuring device using the Hall IC according to the present invention for achieving the above object, and receives an analog sine, cosine wave output from the Hall IC through a series of signal processing process finally the code corresponding to the absolute angle In the rotation angle measuring device using a Hall IC including a main operation processing unit for outputting and a correction processing unit for calculating the LUT (look-up table) for measuring in real operation by measuring the unique characteristic value of each angle measuring device in advance The main operation processor includes: an A / D conversion block for converting an analog sine and cosine wave signal output from the Hall IC into a corresponding digital code as the rotation axis rotates; The offset adjustment is performed so that the intermediate value of the sine and cosine output values converted from the A / D conversion block to the digital code is the origin, and is suitable to prevent saturation caused by the mismatch of the magnitude of the sine and cosine position sensor nominal output voltage. An offset and gain adjustment block for performing tuning by multiplying the scale factor; Normalizing block to remove the effect of the drift gain value according to the temperature change of the permanent magnet; An arc sine LUT control logic block for converting sine and cosine codes into appropriate position angle codes using a look up table (LUT) consisting of output values for addresses and location codes; And an absolute angle code calculation block that performs absolute angle position code calculation for a 360 degree rotation, wherein the correction processing unit receives and records an angle code simultaneously from an absolute angle sensor using a standard encoder mounted on a rotating shaft and a hall IC. ; An angular position code error calculator for which normalized error data is calculated; And a correction LUT data calculator that receives the output data of the angular position code error calculator and the sine and cosine absolute angle position codes together and calculates a correction LUT for removing an error caused by a mechanical assembly tolerance.

The angular position code error calculator comprises an encoder pulse counter for generating an angular code with the same resolution as the corrected sine cosine absolute angle code, and a position code error normalizing which eliminates the offset between the sine cosine absolute angle position code and the encoder code. It further includes a block.

The corrected LUT data operator preferably obtains the FFT value from the normalized data of the sine cosine absolute angle error to remove the high frequency region band noise and the constant magnitude offset of the actual error data.

In addition, the rotation angle measuring method using the Hall IC according to the present invention, after receiving the analog sine and cosine wave output from the Hall IC through a series of signal processing process and finally outputs the code corresponding to the absolute angle, the angle measurement In the rotation angle measurement method using Hall IC that calculates LUT (look-up table) for measuring the unique characteristic value of each device in advance and corrects it in actual operation, analog sine and cosine output from Hall IC as the rotating shaft rotates. An A / D conversion step of converting a wave signal into a corresponding digital code; The offset adjustment is performed so that the intermediate value of the sine and cosine output values converted into the digital code from the A / D conversion step is the origin, and it is suitable to prevent saturation due to the mismatch of the sine and cosine position sensor nominal output voltage magnitudes. An offset and gain value adjustment step of performing tuning by multiplying the scale factor; A normalizing step of removing the influence of the drift gain value due to the temperature change of the permanent magnet; An arc sine LUT control logic step of converting sine and cosine codes into appropriate position angle codes using a LUT (look up table) composed of output values for address and location code; An absolute angle code calculation step of performing absolute angle position code calculation for 360-degree rotation, and simultaneously receiving and recording an angle code from an absolute angle sensor using a standard encoder mounted on a rotating shaft and a hall IC; An angular position code error calculating step in which normalized error data is calculated; And a correction LUT data calculation step of receiving the output data of the angular position code error calculation step and the sine and cosine absolute angle location code together and calculating a correction LUT for removing an error caused by a mechanical assembly tolerance. do.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a control block diagram showing a rotation angle measuring apparatus and a method using a Hall IC according to the present invention.

The present invention is largely divided into two parts, the main operation processing unit 200 performed in the processor chip of the controller, and the LUT (look-up table) for correcting in actual operation by measuring the unique characteristic values for each angle measuring device in advance The correction processing unit 300 for calculation.

As shown in FIG. 1, the main operation processor 200 receives an analog sine and cosine wave output from the Hall IC 100 and finally outputs a code corresponding to an absolute angle through a series of signal processing processes. Used in operating mode. The correction processing unit 300 shown at the bottom is a separate signal processing process for estimating the value to be used in the correction LUT of the main operation processing unit 200. Will be obtained.

FIG. 2 is a control block diagram illustrating the main operation processing unit of the present invention shown in FIG. 1 in more detail.

As shown in the drawing, a detailed arithmetic process of each of the five sub blocks in the main arithmetic processing part will be described.

The A / D conversion block 210 is built in the control-only DSP processor and converts analog sine and cosine wave signals output from the hall IC into corresponding digital codes as the rotating shaft rotates. At this time, the A / D conversion block 210 has a conversion coefficient determined according to the resolution (typically 10 bits) and the operating voltage range (5 volts or 3.3 volts) (for example, 1024/5 unit in the case of 10 bits and 5 volts). / volt). In addition, the rounding error occurs in the A / D conversion process, but the effect on the overall resolution is very small.

The offset and gain adjustment block 220 has a value between 0 and 1023 when the sine and cosine output values converted from the A / D conversion block 210 to the digital code are 10 bits. Adjust the offset as much as possible (for example, in a 5-volt DSP processor, the offset would be 2.5 volts of code, 512). Then tune by multiplying the appropriate scale factor to prevent saturation caused by mismatches in the sine and cosine position sensor nominal output voltage magnitudes.

The normalizing block 230 is a block for removing the influence of the drift gain value due to the temperature change of the permanent magnet.

The output codes NSIN and NCOS of the normalizing block can be expressed as follows.

Normalized sign code NSIN = SinCode * NF

Normalized cosine code NCOS = CosCode * NF

Where NF is the normalizing coefficient, 2 ^ M * Vnorm / sqrt (SinCode ^ 2 + CosCode ^ 2). Vnorm is a scale factor calculated as 2 ^ N-1. SinCode and CosCode are sine and cosine digital codes computed at offset and gain adjustment blocks, respectively. M is the number of bits (typically 10 bits) in A / D conversion, and N is a value for the LUT, which is smaller than 10 bits (typically 8 bits).

Now, the sine and cosine codes passed through the normalizing block remove the effect of the drift gain due to the temperature change of the permanent magnet and are only affected by the nonlinearity error caused by the mechanical assembly tolerance. This effect appears as the sum of the harmonics on the main rotational speed and is solved through the correction process.

The arcsine LUT control logic block 240 converts the sine and cosine codes into appropriate position angle codes using a LUT (Look Up Table) composed of output values for the address and the position code.

In order to convert sine and cosine codes into proper position angle codes, they are generally calculated using trigonometric equations. However, if the value of the cosine function corresponding to the denominator of the tangent function has zero or very small value (overflow), it should be avoided. Therefore, the simplest and most efficient way to convert a computed sine cosine digital code to an angular position code is to use a look up table (LUT) consisting of outputs for the address and position code. However, even in this case, it is important to minimize the size of the LUT to optimize the memory usage of the controller.

In this paper, we propose an arc sine LUT with simple control logic to compute the angular position code for 360-degree rotation. That is, the 360-degree rotation section is divided into four sectors, and each sector is assigned an appropriate offset and sign for the arc sine LUT output corresponding to the actual angle. Each sector has an angular range of 90 degrees in an ideal case, but an unequal angular range in practical cases. A constant offset code for each sector is added to the arcsine LUT output value and the offset value is adjusted according to the NSIN and NCOS code codes. Among the output signals of the normalizing block | NCOS |-| NSIN | The code is used as the address of the LUT. And NSIN, NCOS and | NCOS |-| NSIN | The code sign determines whether the LUT output is inverted or not, from the logic signal sector.

The absolute angle code calculation block 250 performs the absolute angle position code calculation for the 360 degree rotation as the final process of the main operation processing part. One of the outputs of the normalizing block 230 | NCOS |-| NSIN | The code is shifted to the left of the M bits to remove the 2 ^ M coefficients (typically M = 10 bits) used for division operations. And moved | NCOS |-| NSIN | The absolute value of the code will be limited to the value of N bits (0-255 when N = 8 bits). When N = 8 bits, the value of the LUT address code is increased from 0 to 255 in the 45-degree sector and then decreased from 255 to 0 for the 45-degree sector. Thus this computation will be repeated for a 360 degree rotation.

In the case of N = 8 bits, the arc sine LUT output 255 * Asin (0.5 * sqrt (2) / 2 * LUTAddress / 255) is an 8-bit code, which is represented as an angle variable part of a 45 degree sector.

To get the correct angular position code, the arc sine LUT output is shifted by the offset code and the inversion is determined by the logic signal sector. The offset code and logic signal sectors are the arcsine LUT. Created in the control logic block.

FIG. 3 is a control block diagram illustrating in detail the correction processor of the present invention shown in FIG. 1, and FIG. 4 is a block diagram of the angular position code error calculator shown in FIG.

As shown in FIG. 3, the correction processing unit 300 of the present invention includes a memory 310, a DSP-based angular position code error calculator 320, and a PC-based correction LUT data calculator 330.

Referring to the operation of the correction processing unit 300, as shown in Figure 3, simultaneously receiving the angle code from the absolute angle sensor using the standard encoder and the Hall IC mounted on the rotating shaft and writes it to the memory 310 inside the controller do.

These data are then computed by the angular position code error operator 320 installed in the controller processor memory, and the error data normalized, which is then sent back to the calibrated LUT data operator 330 as a sine cosine absolute angle position code. do. Finally, the correction LUT data calculator 330 calculates a correction LUT for removing an error caused by a mechanical assembly tolerance. Detailed description step by step is as shown in FIG.

As shown in FIG. 4, the DSP-based angular position code error operator is composed of two parts, which are the encoder pulse counter 321 and the position code error normalizing block 323, respectively.

Here, the encoder pulse counter 321 generates an angle code having the same resolution (generally 11 bits) as the corrected sine cosine absolute angle code.

Since the encoder is connected to a permanent magnet for a sine cosine position sensor and a rotational axis positioned at an arbitrary angle, the direct calculation of the difference between the sine cosine absolute angle position code and the encoder code has an offset of 11 bits for the 360 degree range. You can give a result. This offset can be eliminated via location code error normalizing block 323.

FIG. 5 is a block diagram of the corrected LUT data calculator shown in FIG. 3.

As shown in the present invention, a correction LUT is calculated as the final process of the correction. Obtaining the FFT value from the normalized data of the sine cosine absolute angle error can remove the high frequency band of the actual error data and the offset of the constant magnitude. Using harmonic sets calculated by applying an FFT to a large enough error data, the correction LUT data can be easily calculated on the PC.

In an ideal state, the FFT analysis of the error data shows only a very small harmonic distribution, mainly caused by rounding errors during DSP operations. However, in the real case, that is, if there is a certain mechanical assembly tolerance, it has a great influence on the actual resolution, and in this case, a resolution difference of several tens of times may occur compared to the ideal case. Therefore, the correction calculation process becomes a very important factor that greatly affects the resolution in actual operation.

The correction technique described here is very important not only for the measurement of the rotation angle but also for the control field where the encoder signal is used as the feedback sensor. This is because the change of the low frequency range caused by the normal error of the uncorrected analog position sensor is performed by the performance of the whole control system. Because it greatly weakens.

Although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the above-described embodiments, and the present invention is not limited to the above-described embodiments without departing from the spirit of the present invention as claimed in the claims. Various modifications can be made by those skilled in the art, and such modifications are intended to fall within the scope of the appended claims.

As described above, according to the rotation angle measuring device and the method using the Hall IC according to the present invention, the electromechanical structure is simpler than other angle sensors, and thus, the installation is easy, and the environmental resistance and durability are excellent. Do. In particular, in terms of cost reduction, which is the most important factor in product production, it has an advantage that it cannot be compared with other sensors. It is easy to replace optical encoder as angle sensor with resolution required in general industrial fields such as servo motor control. A series of computational processing methods and correction techniques have been proposed to correct errors caused by mechanical assembly tolerances and the inherent properties of drift due to the temperature of permanent magnets that are not technically required for high precision hardware configuration. . In other words, system stability and low cost are realized by complementing a simple hardware structure with a series of software, and it can be easily applied through a software operation process in all applications where a dedicated controller exists.

1 is a control block diagram showing a rotation angle measuring apparatus and method using a Hall IC according to the present invention.

Figure 2 is a control block diagram showing in more detail the main operation processing unit of the present invention shown in FIG.

3 is a control block diagram showing in more detail the correction processing unit of the present invention shown in FIG.

4 is a block diagram of the angle position code error calculator shown in FIG.

FIG. 5 is a block diagram of the correction LUT data operator shown in FIG. 3; FIG.

<Description of the symbols for the main parts of the drawings>

100: Hall IC 200: main operation processing unit

210: A / D conversion block 220: offset and gain value adjustment block

230: normalizing block 240: arc sine control logic block

250: absolute angle code calculation block 300: correction processing unit

310: memory 320: angle position code error calculator

321: Encoder Counter 323: Error Normalizing Block

330 correction LUT data calculator

Claims (6)

Main operation processing unit which receives analog sine and cosine wave output from Hall IC and finally outputs code corresponding to absolute angle through a series of signal processing process, and measures in advance unique characteristics of each angle measuring device. In the rotation angle measuring device using a Hall IC including a correction processing unit for calculating a look-up table (LUT) for correction, The main operation processing unit may include an A / D conversion block for converting an analog sine and cosine wave signal output from the Hall IC into a corresponding digital code as the rotation axis rotates; Adjust the offset so that the middle value of the sine and cosine output values converted from the A / D conversion block to the digital code is the origin, and prevent the saturation caused by the mismatch of the sine and cosine position sensor nominal output voltage magnitudes. An offset and gain adjustment block for multiplying the coefficients to perform tuning; Normalizing block to remove the effect of the drift gain value according to the temperature change of the permanent magnet; An arc sine LUT control logic block for converting sine and cosine codes into appropriate position angle codes using a look up table (LUT) consisting of output values for addresses and location codes; And an absolute angle code calculation block for performing absolute angle position code calculation for 360 degree rotation, and the correction processing unit A memory for simultaneously receiving angle codes from an absolute angle sensor using a standard encoder mounted on a rotating shaft and a Hall IC; An angular position code error calculator for which normalized error data is calculated; And a correction LUT data calculator that receives the output data of the angular position code error calculator and the sine and cosine absolute angle position codes together and calculates a correction LUT for removing an error caused by a mechanical assembly tolerance. Rotation angle measuring device using IC. The method of claim 1, The angular position code error calculator comprises an encoder pulse counter for generating an angular code with the same resolution as the corrected sine cosine absolute angle code, and a position code error normalizing which eliminates the offset between the sine cosine absolute angle position code and the encoder code. Rotation angle measuring device using a Hall IC, characterized in that it further comprises a block. The hall of claim 1, wherein the corrected LUT data calculator obtains an FFT value from the normalized data of the sine cosine absolute angle error, and removes a high frequency region band noise and a constant size offset of the actual error data. Rotation angle measuring device using IC. LUT for receiving analog sine and cosine wave output from Hall IC and finally outputting code corresponding to absolute angle through a series of signal processing process and measuring unique characteristic values of each angle measuring device in advance A method of measuring a rotation angle using a Hall IC for calculating a look-up table, the method comprising: an A / D conversion step of converting an analog sine and cosine wave signal output from a Hall IC into a corresponding digital code as a rotation axis rotates; The offset adjustment is performed so that the intermediate value of the sine and cosine output values converted into the digital code from the A / D conversion step is the origin, and it is suitable to prevent saturation due to the mismatch of the sine and cosine position sensor nominal output voltage magnitudes. An offset and gain value adjustment step of performing tuning by multiplying the scale factor; A normalizing step of removing the influence of the drift gain value due to the temperature change of the permanent magnet; An arc sine LUT control logic step of converting sine and cosine codes into appropriate position angle codes using a LUT (look up table) composed of output values for address and location code; An absolute angle code calculation step of performing absolute angle position code calculation for 360-degree rotation, and simultaneously receiving and recording an angle code from an absolute angle sensor using a standard encoder mounted on a rotating shaft and a hall IC; An angular position code error calculating step in which normalized error data is calculated; And a correction LUT data calculation step of receiving the output data of the angular position code error calculation step and the sine and cosine absolute angle location code together and calculating a correction LUT for removing an error caused by a mechanical assembly tolerance. Rotation angle measurement method using a Hall IC. 5. The method of claim 4, wherein the step of calculating the angular position code error comprises: an encoder pulse counter step of generating an angular code of the same resolution as the corrected sine cosine absolute angle code, and an offset between the sine cosine absolute angle position code and the encoder code. Rotation angle measurement method using a Hall IC, characterized in that it further comprises a normalizing step of removing the position code error. 5. The method of claim 4, wherein the correcting LUT data calculation step comprises: A method of measuring rotation angle using Hall IC, characterized by obtaining an FFT value from normalized data of an sine cosine absolute angle error, and removing a high frequency region band noise and a predetermined offset of the actual error data.