JP2010139405A - Encoder signal processing method, encoder device, and servomotor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encoder signal processing method, encoder device and a servomotor, which are applicable to a galvanoscanner, can be temperature compensated, are highly accurate and are excellent in a high speed response. <P>SOLUTION: The amplitude of an encoder signal is gain adjusted by a square calculation means for squaring each of 2-phase sine wave signal output from an encoder signal generator, an addition means for adding the squared 2-phase sine wave signal output from the square calculation means, a means for calculating a square root of the output of the addition means, and a means for calculating a compensation coefficient of the amplitude. Further, by an amplifier for processing the 2-phase sine wave signal based on a differential input, a delayed waveform to the original waveform is formed at a certain interval and a multiplied signal is obtained, which is effective, even when the object to be detected is accelerated/decelerated or subjected to a change of load. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an encoder signal processing method of an encoder applicable to a galvano scanner for performing, for example, tracking control of laser light with high accuracy, an encoder device, and a servo motor including the encoder device.

  Conventionally, in an encoder for detecting the position of a moving body, in order to further divide an analog signal output and achieve high resolution, various encoders such as those disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 1-163615) are available. An interpolation circuit is used.

  In addition, as a means for increasing detection resolution in a magnetic encoder, there is a method for dealing with high resolution by using a magnetic sensor in which a plurality of magnetoresistive elements are arranged, which is disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-105134. .

  On the other hand, as a device requiring a high-resolution encoder, there is a galvano scanner used for a high-precision laser processing machine, a three-dimensional measuring machine, or the like. This galvano scanner is disclosed in, for example, Japanese Patent Application Laid-Open No. 2006-224142.

  The galvano scanner is composed of a galvano mirror that reflects laser light and a servo motor that drives the galvano mirror that scans the laser light.

  The servo motor is mainly provided with an optical rotary encoder as a galvanometer mirror position detecting means.

JP-A-1-163615 JP 2000-105134 A JP 2006-224142 A

  In recent years, it has been desired that equipment using a galvano scanner, such as a laser processing machine, can control the position of laser light with higher accuracy and higher speed.

  Considering only high-speed position control, a magnetic encoder with excellent high-speed response is suitable, but there is a limit to the number of magnetic poles that can be formed on the disk within the range that can be detected by the magnetic sensor. Thus, magnetic encoders with greatly reduced resolution were not suitable for galvano scanners.

  According to the method using the interpolation circuit described in Patent Document 1 and the like, it is theoretically possible to increase the detection resolution of the original signal of the magnetic encoder infinitely, but because it is essentially multiplication by the PLL. The higher the resolution, the greater the influence of various error factors.

  In particular, when acceleration occurs due to acceleration / deceleration or load fluctuations, it may not be an accurate multiplication, and there may be insignificant divisions. Therefore, the accuracy and reliability required for a galvano scanner are actually required. Therefore, it is difficult to increase the resolution to several tens of times or more.

  According to the method of arranging the magnetoresistive effect elements described in Patent Document 2 and the like, it is possible to increase the resolution with high accuracy by the output of four or more bridge circuits without changing the number of magnetic sensors. Since the number of magnetoresistive elements that can be arranged in the magnetic sensor is limited, it is difficult to obtain the high resolution necessary for the galvano scanner.

  On the other hand, the present invention aims to realize a highly accurate encoder device applicable to a galvano scanner, and specifically, realizes an encoder device having a high resolution of several million pulses or more even with a magnetic type. To do.

  In order to solve these problems, in the present invention, a relational expression of voltage and resistance at each point on the circuit determined when a two-phase sinusoidal encoder signal is input to a circuit including a certain resistor and amplifier, and an additive theorem. Is used to create an arbitrary delayed waveform with respect to the original signal of the encoder.

  Specifically, according to the first aspect of the present invention, an encoder signal processing method (signal 1, signal 2) is a two-phase sine wave having a phase difference of π / 2, which is a signal processing method of an encoder for detecting the position of a moving body. Is input to a circuit including an amplifier arranged so that the following expression holds and resistors (R1, R2, R3) in three sections.

  The circuit includes at least one amplifier and at least three resistors, and is arranged so that at least m (m is a positive integer) and the following expression is satisfied. .

  The relational expression of Vin1, Vin2, and Vout−Vcom shows the relationship between the two-phase encoder signal, the voltage on the circuit, and the resistance.

  The relational expression of R3 shows the relation of the resistance R3 corresponding to the resistance ratio [(R1 / R2) = tanφn] of the resistance R1 and the resistance R2 when the delayed waveform is formed.

  The sin (θ−φn) relational expression shows the relationship between the sinusoidal waveform of the encoder signal and the sinusoidal waveform of the two-phase encoder signal by developing a sinusoidal waveform delayed by φn in phase angle with the addition theorem. Yes.

  From these equations, a plurality of sine waveforms delayed by φn in phase angle with respect to the sine waveform sinθ of the encoder signal are formed at equal intervals of the phase difference Δφ by the resistance ratio between the resistor R1 and the resistor R2. The encoder signal processing method was adopted.

  According to the second aspect of the present invention, the square calculation means for squaring each of the two-phase sine wave signals output from the signal generation source and the squared two-phase sine wave signal output from the square calculation means are added. The gain is adjusted by the means, the means for calculating the square root of the output of the adding means, and the means for calculating the correction coefficient of the amplitude.

  An encoder signal (signal 1 and signal 2), which is a two-phase sine wave having a phase difference of π / 2, the gain of which is adjusted in gain, is arranged with an amplifier arranged so that the following expression is satisfied, and resistors (R1, R2 in three sections) , R3).

  This circuit is composed of at least one amplifier and at least three resistors, and is arranged so that at least m (m is a positive integer) and the following expression is satisfied.

  An encoder characterized in that a plurality of sinusoidal waveforms delayed by φn in phase angle with respect to the sinusoidal waveform sinθ of the encoder signal are formed at equal intervals of the phase difference Δφ by the resistance ratio of the resistor R1 and the resistor R2 in the above equation. Signal processing method.

  According to a third aspect of the present invention, the square calculation means for squaring each of the two-phase sine wave signals output from the signal generation source and the squared two-phase sine wave signal output from the square calculation means are added. The gain is adjusted by the means, the means for calculating the square root of the output of the adding means, and the means for calculating the correction coefficient of the amplitude.

  An encoder signal (signal 1 and signal 2), which is a two-phase sine wave having a phase difference of π / 2, the gain of which is adjusted in gain, is arranged with an amplifier arranged so that the following expression is satisfied, and resistors (R1, R2 in three sections) , R3).

  This circuit is composed of at least one amplifier and at least three resistors, and is arranged so that at least m (m is a positive integer) and the following expression is satisfied.

  An encoder characterized in that a plurality of sinusoidal waveforms delayed by φn in phase angle with respect to the sinusoidal waveform sinθ of the encoder signal are formed at equal intervals of the phase difference Δφ by the resistance ratio of the resistor R1 and the resistor R2 in the above equation. Signal processing method.

  According to a fourth aspect of the present invention, in the signal processing method of the encoder according to any one of the first to third aspects, the delay waveform formed is set to have a threshold value ½ of the peak / peak value of the amplitude V, The encoder signal processing method is characterized by using a square wave.

  According to a fifth aspect of the present invention, there is provided an encoder device comprising means capable of performing the signal processing method according to any of the first to fourth aspects.

  The invention according to claim 6 is the encoder device according to claim 5, which is a rotary encoder for detecting a rotation angle of the rotating body.

  The invention according to claim 7 is the encoder device according to claim 5 or 6, characterized in that the means for detecting the rotation angle is magnetic.

  The invention according to claim 8 is a servo motor comprising the encoder device according to any one of claims 5 to 7.

  According to the first aspect of the present invention, the amplitude is reduced by the influence of the resistance arranged in the circuit that forms the delayed waveform by multiplying the signal waveform of the encoder in real time by a circuit having a simple configuration. It is possible to create a highly accurate waveform that corrects for.

  According to the second aspect of the present invention, since the error caused by the resistance in the circuit, the secular change, the fluctuation of the moving speed of the detection target, the fluctuation of the amplitude of the original signal caused by the temperature environment and the like are corrected, the real-time is accurately obtained. The output signal divided by multiplication can be obtained.

  According to the third aspect of the invention, in addition to the correction of the original signal with respect to factors such as aging and temperature environment, the adjustment is performed in consideration of the influence of the resistor arranged in the circuit forming the delayed waveform, so that the higher An output signal that is multiplied and divided in real time with accuracy can be obtained.

  According to the fourth aspect of the invention, since the digital output can be obtained by converting the high-resolution analog output, the signal processing in the subsequent processes becomes easy.

  According to invention of Claim 5, the encoder apparatus which can detect the positional information on a moving body with high precision can be obtained.

  According to the sixth aspect of the present invention, it is possible to detect the rotational angle information of the rotating body with high accuracy, and it is possible to obtain a rotary encoder device applicable to a servo motor for a galvano scanner.

  According to the seventh aspect of the present invention, it is possible to obtain a rotary encoder device applicable to a servo motor for a galvano scanner having a high resolution of 1 million pulses or more and excellent in high-speed response.

  According to the eighth aspect of the invention, it is possible to obtain a servo motor for a galvano scanner that can control the position of the galvano mirror with high accuracy.

  In the present embodiment, as the best mode, the present invention relates to a highly accurate magnetic encoder capable of finally obtaining a position detection signal of millions of pulses, and a signal processing method for realizing a servo motor including the encoder. The content will be described in the following order with reference to the accompanying drawings.

[A] Encoder signal division method [B] Signal adjustment [C] Linearization of output signal [D] Encoder device and servo motor [E] Modification

[A] Encoder signal division method FIG. 1 shows a schematic structure of a two-phase magnetic encoder. A magnetic drum 2 is attached to the rotating shaft 1 of the motor 10, and a large number of N poles and S poles are magnetized on the outer periphery of the magnetic drum 2 at uniform intervals.

  An MR sensor 3 composed of two magnetoresistive elements is disposed at a position facing the magnetic pole surface of the magnetic drum 2. A two-phase sine wave signal generated by the MR sensor 3 is an original signal of the magnetic encoder.

  In this embodiment, magnetic poles are formed on the outer periphery of the magnetic drum 2 at a magnetization pitch of 0.08 mm / 1,024 p. As a result, the output pulse 1,024 P / R of the original signal is determined.

  Further, the sine wave signals generated from the two MR sensors are arranged so as to have a phase difference of π / 2. That is, the waveforms of the two sine wave signals can be expressed by sin θ and cos θ.

  Since the output signal from the MR sensor is a small signal of several tens of mV, it is amplified using a differential amplifier circuit. The two amplified output signals are expressed by the following expression obtained by multiplying the amplified amplitude voltage by sin θ and cos θ.

  Next, encoder signals A and B are multiplied by 1,024 by inputting them into the circuit of FIG. At this time, using the relational expression between voltage and resistance at each point on the circuit of FIG. 2 and the addition theorem, the encoder signal is multiplied by making a delayed waveform at a constant interval. explain.

  In the circuit of FIG. 2, when the inverting input (−) is Vcom due to the operation of the operational amplifier, the non-inverting input terminal (+) is also Vcom, and when the encoder signals A and B are input to the circuit of FIG.

  Further, when the output terminal voltage of the operational amplifier is Vout, the following equation is established in relation to I1, I2, and I3 flowing through the resistors R1, R2, and R3.

When the above equation ([Equation 9]) is modified, it is expressed by the following equation.

A waveform delayed by φ with respect to sin θ can be expressed by the following equation by developing using the addition theorem.

Here, the relationship of the following equation can be selected.

  Therefore, the delay φ is determined by the ratio of R1 and R2, and a free delay waveform can be created by changing the combination of the resistance ratios of R1 and R2.

  That is, in this embodiment, in order to obtain a signal waveform obtained by dividing the encoder signal by 1,024, a circuit having 1,024 combinations of resistance ratios of R1 and R2 is required.

  In FIG. 2, R1 indicates a resistance between a and c, R2 indicates a resistance between b and d, and R3 indicates a resistance between c and e, and a plurality of resistors may be arranged on the circuit.

  The conditions for forming a plurality of sine waveforms delayed by φn in phase angle by the resistance ratio of the circuit shown in FIG. 2 with respect to the sine wave of the encoder signal at equal intervals of phase difference Δφ = 2π / m are: From the relational expression of [Equation 12], it can be summarized as follows.

  That is, if m = 1,024 in the above equation ([Formula 13]), a signal obtained by dividing the original signal by 1,024 can be obtained.

  At this time, when the original signal is 1,024 P / R, an output signal of 1,024 × 1,024 = 1,048,576 P / R can be obtained.

  This output signal is a waveform that is multiplied and divided in real time in accordance with the fluctuating frequency even during acceleration / deceleration of the detection target or when the load is changed.

[B] Signal adjustment <Adjustment 1>
The amplitude of the delayed waveform of φn determined by the resistance ratio [R1 / R2] (n) of the resistors R1 and R2 created by the circuit of FIG. 2 is reduced by the influence of the resistor R3 although the maximum amplitude is slightly smaller than the amplitude V. fluctuate.

  From the relationship of the following equation that can be derived using the resistance ratio [R1 / R2] of the resistors R1 and R2, R3 is determined so as to maintain the amplitude V, thereby correcting the gain for φn.

<Adjustment 2>
In addition, the original encoder signal fluctuates slightly due to temporal factors such as aging, spatial factors such as temperature environment, and the moving speed of the detection target. A method for correcting this variation will be described.

  FIG. 3 is a block diagram relating to the signal processing of the encoder in the present embodiment. As shown in FIG. 3, the output signal from the MR sensor amplified using the differential amplifier circuit is corrected so as to have a constant maximum amplitude before being input to the delay waveform forming circuit (FIG. 2). .

  The amplitude correction process at this time includes a square calculation means for squaring each of the two-phase sine wave signals, a means for adding the squared two-phase sine wave signals output from the multiplication calculation means, and an output of the addition means. Means for calculating a square root and means for calculating an amplitude correction coefficient.

  The maximum amplitude of the output signal that is not affected by the variation factor is V with respect to the maximum amplitude v of the original two-phase sine wave signal from the MR sensor, and the maximum amplitude of the amplified output signal including the variation factor Is V ′. That is, it is expressed by the following formula.

  When the output signal after amplification of the two-phase sine wave in the case of including a variation factor is squared by the square calculation unit, and the squared two-phase sine wave signal is added by the addition unit, the output result is expressed by the following equation.

  The absolute value of V 'can be obtained by calculating this output result by means for calculating the square root.

  A coefficient for converting the absolute value of V ′ to V is determined by means for calculating a correction coefficient, and the maximum amplitude of the encoder signal is adjusted to V based on the correction coefficient.

[C] Linearization of the output signal The gain is adjusted, and the formed delayed waveform of the sine wave is converted to a square wave with the threshold value being ½ of the peak / peak value of the amplitude V.

[D] Encoder device and servo motor <Encoder device>
As means for executing the above-described methods [A] to [C], a rotary encoder device is configured mainly using a split IC, EEPROM, temperature sensor, MPU, etc. in addition to the magnetic drum and MR sensor.

  The split IC includes a circuit that creates a delay waveform at equal intervals with respect to the sine wave signal of the encoder according to the number of delay waveforms.

  The EEPROM stores the two-phase signal (sin / cos) angle calculation result and the like, thereby enabling high-speed calculation processing.

The MPU performs various arithmetic processes such as constantly correcting temperature drift according to the output of the temperature sensor.
<Servo motor>

  A motor control system is configured by a motor equipped with this encoder device. The servo motor of the present embodiment is effective as a servo motor for a galvano scanner because it is temperature compensated, has excellent high-speed response, and can control the position of the motor output shaft with high accuracy.

[E] Modifications As described above, the embodiment using mainly the magnetic rotary encoder has been described as the best mode of the present invention, but it is naturally possible to apply in various forms without departing from the scope of the present invention. It is. For example, the following examples are given.

<Example 1: Linear encoder>
The present invention can be applied to any type of encoder as long as it is an encoder that outputs two-phase sine wave signals having a phase difference of 90 degrees. For example, by applying to a linear encoder, the positioning of the linear motion body can be performed with high accuracy.

<Example 2: Optical encoder>
In addition, when applied to an optical encoder, the rotary drum can be provided with position information of higher division than in the case of a magnetic type, so that an encoder having higher resolution can be obtained.

<Example 3: Division by pulse multiplication circuit>
The square wave obtained by converting the delayed waveform of the sine wave may be further improved in resolution through a normal multiplication circuit that captures the rising and falling edges of each phase pulse.

  For example, an output signal of 1,024 × 1,024 = 1,048,576 P / R divided by 1,024 from an original sine wave signal of 1,024 P / R is converted into a square wave, and then passed through a quadruple circuit. , 194, 304 P / R output signals can be obtained.

<Example 4: Configuration of encoder device>
The components of the control system such as the divided IC, EEPROM, and MPU of the encoder device, which are specific means of the encoder signal processing method, are not necessarily arranged integrally with the detector main body.

  Further, the control system for performing the encoder signal processing method of the present invention can be realized by any configuration using various ICs such as an analog circuit, a digital circuit, a DSP, software, and the like by arranging a converter between arbitrary blocks.

1 is a structural diagram of a magnetic encoder according to an embodiment of the present invention. 1 is a circuit diagram of a differential amplifier circuit according to an embodiment of the present invention. It is a block diagram of signal processing concerning an embodiment of the invention.

Explanation of symbols

1 Rotating shaft 2 Magnetic drum 3 MR sensor 10 Motor

Claims (8)

An encoder signal processing method for detecting the position of a moving body,
An encoder signal (signal 1 and signal 2) that is a two-phase sine wave having a phase difference of π / 2 is provided with an amplifier arranged so that the following expression is satisfied, and resistances (R1, R2, and R3) in three sections. Input to the circuit,
An encoder signal processing method characterized in that a sinusoidal waveform delayed by φn in phase angle with respect to the sinusoidal waveform sinθ of the encoder signal is created by a resistance ratio between the resistor R1 and the resistor R2.

An encoder signal processing method for detecting the position of a moving body,
A square calculation means for squaring each of the two-phase sine wave signals output from the signal generation source, a means for adding the squared two-phase sine wave signals output from the square calculation means, and a square root of the output of the addition means An encoder signal (signal 1, signal 2) that is a two-phase sine wave having a phase difference of π / 2, the amplitude of which is gain-adjusted by means for calculating and means for calculating an amplitude correction coefficient,
Input to an amplifier arranged so that the following equation holds, and a circuit including resistors (R1, R2, R3) in three sections,
The circuit is composed of at least one amplifier and at least three resistors, and is arranged so that at least m (m is a positive integer) and the following expression holds. And
An encoder signal characterized in that a plurality of sinusoidal waveforms delayed by φn in phase angle with respect to the sinusoidal waveform sinθ of the encoder signal are formed at equal intervals of a phase difference Δφ by a resistance ratio between the resistor R1 and the resistor R2. Processing method.

An encoder signal processing method for detecting the position of a moving body,
A square calculation means for squaring each of the two-phase sine wave signals output from the signal generation source, a means for adding the squared two-phase sine wave signals output from the square calculation means, and a square root of the output of the addition means An encoder signal (signal 1, signal 2) that is a two-phase sine wave having a phase difference of π / 2, the gain of which is adjusted by gain by means for calculating and means for calculating an amplitude correction coefficient,
Input to an amplifier arranged so that the following equation holds, and a circuit including resistors (R1, R2, R3) in three sections,
The circuit is composed of at least one amplifier and at least three resistors, and is arranged so that at least m (m is a positive integer) and the following equation is satisfied. And
An encoder signal characterized in that a plurality of sinusoidal waveforms delayed by φn in phase angle with respect to the sinusoidal waveform sinθ of the encoder signal are formed at equal intervals of a phase difference Δφ by the resistance ratio of the resistor R1 and the resistor R2. Processing method.

In the encoder signal processing method according to any one of claims 1 to 3,
A signal processing method for an encoder, wherein the formed delay waveform is a square wave with a threshold value set to ½ of the peak / peak value of the amplitude V.   An encoder apparatus comprising means capable of performing the signal processing method according to claim 1.   The encoder apparatus according to claim 5, wherein the encoder apparatus is a rotary encoder that detects a rotation angle of the rotating body.   7. The encoder apparatus according to claim 5, wherein the rotation angle detecting means is a magnetic type.   A servo motor comprising the encoder device according to claim 5.

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