JP2007114165A - Device and method for detecting position of moving object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position detection device capable of suppressing phase delay, and raising the accuracy of position detection, even if electrical noises are superimposed on the sinusoidal signals of two phases generated by an encoder. <P>SOLUTION: The position detection device is provided with a position command device 54 for setting a target position of a moving object, and a phase difference detection means 72 to which a sinusoidal signal of A phase and a sinusoidal signal of B phase different in phase by 90 degrees from the sinusoidal signal of the A phase, which the encoder outputs, and a cosine oscillation signal of the A phase and a cosine oscillation signal of the B phase different in phase by 90 degrees from the cosine oscillation signal of the A phase, which are based on the target position, are input, to detect the phase difference between the cosine oscillation signals and the sinusoidal signals. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus and a method for detecting a position of a moving body, and in particular, based on a two-phase sine wave signal output from an encoder provided on the moving body, for example, a high-resolution encoder or a resolver encoder. The present invention relates to a position detecting apparatus and method for detecting.

  Conventionally, when detecting the rotation angle of a moving body, for example, a rotating body using a sensor, response delay is eliminated with respect to the rotation angle signal of the sensor, and electrical noise is mixed in the rotation angle signal. In addition, as a rotation angle detection device that suppresses the influence of noise regardless of the noise level, for example, the one described in Patent Document 1 is known.

  FIG. 6 is a schematic functional block diagram of a program executed in the conventional rotation angle detection device described in Patent Document 1. As shown in FIG. 6, the program 16 includes a signal processing unit 26 that obtains an output signal θ0 of the rotating shaft of the rotating body based on the output signal θ0 of the resolver, and a motor control unit 28 that controls the motor based on the output signal θ0. The monitor output unit 30 displays the correction angle θ1 on the monitor.

The signal processing unit 26, an acceleration calculation unit 32 for calculating an estimated acceleration gamma rotary shaft output signal .theta.0 2 derivative to the acceleration limiting unit 34 for limiting the estimated acceleration gamma at maximum threshold value gamma _MAX and a minimum threshold value gamma _MIN When a threshold value correcting unit 36 for correcting the maximum threshold value gamma _MAX and a minimum threshold value gamma _MIN by magnitude of estimated acceleration gamma and maximum threshold value gamma _MAX and a minimum threshold value gamma _MIN, the processing result of the acceleration limiting portion 34 limits the estimated acceleration gamma And a rotation angle calculation unit 38 for calculating the correction angle θ1 of the rotation axis based on

  Conventionally, as shown in FIG. 7, for example, a rotation angle detection device 55 applied to an electric motor control device 51 is known as a rotation angle detection device. The motor control device 51 is a control device that controls the position and speed of the rotor of an electric motor 52, for example, an AC or DC motor, and includes an encoder 53, a position command device 54, a rotation angle detection device 55, a subtractor 56, and a low-pass filter. A circuit (hereinafter referred to as an LPF circuit) 57, a PI circuit 58, and an amplifier circuit 59 are provided.

  The encoder 53 is a signal generator that is connected to the rotation shaft of the rotor of the electric motor 52 and generates a two-phase sine wave signal corresponding to the rotation angle. Specifically, an A-phase sine wave signal A (hereinafter referred to as signal A) and a B-phase sine wave signal B (hereinafter referred to as signal B) having a phase difference of 90 degrees with respect to the A signal are output 2 Phase signal generator.

  The position commander 54 is a commander that sets a target value of the rotation angle of the rotor of the electric motor 52.

  The rotation angle detection device 55 includes an LPF circuit 60, an LPF circuit 61, an arctan (A / B) calculator 62, and an LPF circuit 63.

  The LPF circuit 60 and the LPF circuit 61 receive the signal A and the signal B from the encoder 53, respectively, and the signal A and the signal B excluding electric noise superimposed on the signal A and the signal B are arctan (A / B). The result is output to the calculator 62.

  The arctan (A / B) calculator 62 receives the signal A and the signal B from which the noise has been removed, substitutes the signal A and the signal B into the arctan (A / B) calculation formula, and obtains the result of the calculation. The rotation angle is output to the LPF circuit 63. The noise is further removed by the LPF circuit 63 and the rotation angle θ of the encoder 53 is output to the subtractor 56.

  The subtracter 56 inputs the rotation angle target value and the rotation angle θ by the position commander 54, subtracts the rotation angle θ from the rotation angle target value, and sends the rotation angle deviation obtained as a result of the calculation to the LPF circuit 57. Output. The LPF circuit 57 removes noise superimposed on the rotation angle deviation and outputs it to the PI circuit 58.

Via the PI circuit 58 and the amplifier circuit 57, for example, an inverter circuit, the rotation angle deviation is controlled to be zero, and the position and speed of the rotor of the electric motor 52 are controlled.
JP 2003-222518 A

As described above, in the conventional position detection device, the output signal θ0 is input from the resolver that detects the rotation angle of the rotating body, and the output signal θ0 is second-order differentiated to obtain the estimated acceleration γ. The estimated acceleration γ thus obtained is limited by a maximum threshold value γ _MAX that is a positive value and a minimum threshold value γ _MIN that is a negative value, thereby obtaining a corrected acceleration γ1. The obtained corrected acceleration γ1 is integrated to obtain a corrected speed, and this corrected speed is integrated to obtain a corrected angle.

  There is a possibility that the rotation angle obtained as described above may not be sufficient in terms of accuracy and noise of the rotation angle of the high resolution encoder. This is because in a high-resolution encoder, speed and acceleration are determined by estimation, and it is difficult to cope with changes in acceleration.

  Further, when an LPF circuit is used to remove electrical noise superimposed on the A-phase and B-phase signals by the encoder 53, there is a possibility that a problem of angular error due to phase delay may occur.

  Accordingly, an object of the present invention is to provide a position detection apparatus and method that can suppress phase delay and improve position accuracy even if electrical noise is superimposed on a two-phase sine wave signal by an encoder. To do.

  In order to achieve the above object, the present invention provides a position detection device for detecting the position of a moving body based on two-phase sine wave signals of A phase and B phase output from an encoder connected to the moving body. Based on a position commander for setting a target position of the moving body, an A-phase sine wave signal output from the encoder, a B-phase sine wave signal whose phase differs from the A-phase sine wave signal by 90 degrees, and the target position An A-phase cosine wave oscillation signal and a B-phase cosine wave oscillation signal whose phase is different from the A-phase cosine wave oscillation signal by 90 degrees are input, and the phase difference between the cosine wave oscillation signal and the sine wave signal is detected. Phase difference detection means, and the frequency and phase of the sine wave signal are matched with the frequency and phase of the cosine wave oscillation signal so that the phase difference is zero, so that the position of the moving body is the same as the target position. To detect the position of the moving object And features.

  Further, preferably, the phase difference detection means inputs a target position, and converts the target position into an A-phase cosine wave oscillation signal and a B-phase cosine wave oscillation signal, and an A-phase converter. The first multiplier for inputting the first sine wave signal and the A-phase cosine wave oscillation signal and outputting the first multiplication signal obtained by multiplying these signals, the B-phase sine wave signal and the B-phase sine wave signal A cosine wave oscillation signal is input, a second multiplier that outputs a second multiplication signal obtained by multiplying these signals, a first multiplication signal and a second multiplication signal are input, and these signals are input. And an adder that outputs a phase difference between a sine wave signal and a cosine wave oscillation signal obtained by adding the two.

  Further, in the position detection method for detecting the position of the moving body based on the A-phase and B-phase two-phase sine wave signals output from the encoder connected to the moving body, the A of the two-phase sine wave signals Detecting a phase sine wave signal, detecting a phase B sine wave signal whose phase is different by 90 degrees from the phase A sine wave signal, synchronized with the frequency of the sine wave signal, and Generating an A-phase cosine wave oscillation signal based on the target position, generating a B-phase cosine wave oscillation signal that is 90 degrees out of phase with the A-phase cosine wave oscillation signal, and an A-phase sine wave signal And the A-phase cosine wave oscillation signal are multiplied to generate a first multiplication signal, and the B-phase sine wave signal and the B-phase cosine wave oscillation signal are multiplied to generate a second multiplication signal. And adding a first multiplication signal and a second multiplication signal. And generating a phase difference between the cosine wave oscillation signal and the sine wave signal, and when the phase difference is controlled to be zero, the target position matches the position of the moving object. The position of the moving body is detected.

  An example of the moving body in the above position detection apparatus and method is a rotor of an electric motor.

  As described above, according to the present invention, even when noise is superimposed on a two-phase sine wave signal by an encoder, phase delay can be suppressed and position detection accuracy can be improved.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a control block diagram showing an embodiment in which a rotation angle detection device according to the present invention is applied to an electric motor control device. 1, elements having the same functions as those in FIG. 9 are denoted by the same reference numerals.

  In FIG. 1, an electric motor control device 71 is a control device that controls the position and speed of a rotor of an electric motor 52, for example, an AC or DC electric motor, and includes an encoder 53, a rotation angle detection device 72, an LPF circuit 57, and a PI circuit 58. And an amplifier circuit 59. The rotation angle detection device 72 includes phase difference detection means 73 and a position command device 54.

  The phase difference detection means 73 receives the signals A and B from the encoder 53 and the rotation angle target value from the position commander 54, and outputs the sin value of the phase difference φ of the rotation angle. The sin value is output to the PI circuit 58 via the LPF circuit 97. The PI circuit 58 includes a position controller (not shown) and a speed controller (not shown), and controls the position and speed of the motor 52 via an amplifier circuit 59, for example, an inverter circuit and a drive circuit. The rotor is controlled to a predetermined position and speed.

  Next, the configuration of the rotation angle detection device 72 will be described in detail. The rotation angle detection device 72 includes the position commander 54 and the phase difference detection means 73 as described above.

  The position commander 54 is a commander that sets a target rotation angle value of the rotor of the electric motor 52. The phase difference detection means 73 includes a SIN / COS converter (A) 74, a first multiplier 75, a second multiplier 76, and an adder 77.

  The SIN / COS converter (A) 74 receives the rotation angle target value from the position commander 54, and outputs a cosine wave oscillation signal C of the A phase out of the two phases (hereinafter referred to as a signal C) as a first multiplier. The B phase cosine wave oscillation signal D (hereinafter referred to as signal D) is output to the second multiplier 76.

  The first multiplier 75 receives the signal A from the encoder 53 and the signal C from the SIN / COS converter (A) 74, multiplies the signal A and the signal C, and obtains a first multiplication signal obtained as a result of the operation. E is output to the adder 77.

  The second multiplier 76 receives the signal B from the encoder 53 and the signal D from the SIN / COS converter (A) 74, multiplies the signal B and the signal D, and obtains a second multiplication signal obtained as a result of the operation. F is output to the adder 77.

  The adder 77 inputs the first multiplication signal E and the second multiplication signal F, adds the first multiplication signal E and the second multiplication signal F, and determines the position of the rotation angle obtained as a result of the calculation. The sin value G of the phase difference φ is output to the LPF circuit 57.

  The LPF circuit 57 is a filter that inputs a sin value G of the phase difference φ and passes a signal having a predetermined frequency or lower, and is a generally known circuit, for example, a combination of a resistor, a capacitor, and an inductor.

FIG. 2 is a diagram showing the phase difference between the sine wave signal of the encoder and the rotation angle with respect to the elapsed time in the rotation angle detection device according to the present invention.

  2A shows the sine wave signal A of the encoder, FIG. 2B shows the sine wave signal B whose phase is 90 degrees different from that of the sine wave signal A, and FIG. 2D shows a rotation angle phase difference curve in which electrical noise is superimposed on the sin value of the phase difference φ as the signal G. FIG.

Next, the operation of the rotation angle phase difference detection means 72 will be described. In FIG. 1, the signal A by the encoder 53 is, for example,
A = sinω _e t (1)
And

Signal B is
B = sin (ω _e t + π / 2) = cosω _e t (2)
And The signal C by the SIN / COS converter (A) 74 is, for example,
C = cos (ω _o t−φ) (3)
And

Signal D is
D = cos (ω _o t−φ + π / 2) = − sin (ω _o t−φ) (4)
And Here, ω _e and ω _o indicate the respective angular frequencies of the signals A and B by the encoder 53 and the signals C and D by the SIN / COS converter (A) 74.

When the motor controller 71 controls the position and speed of the rotor of the motor 52 normally, the angular frequency ω _e of the encoder 53 and the angular frequency ω _o of the SIN / COS converter (A) 74 are instantaneously the same. It can be assumed that the angular frequency is ω. Φ represents the phase difference of the rotation angle between the signal from the encoder 53 and the signal from the SIN / COS converter (A) 74. Therefore, in the following description, ω _e and ω _o are ω.

Therefore, the first multiplier 75 multiplies the signal A by the signal C and the first multiplication signal E obtained as a result of the operation is
E = A × C = sinωt × cos (ωt−φ) (5)
It becomes.

Similarly, the second multiplier 76 multiplies the signal B by the signal D, and the second multiplication signal F obtained as a result of the operation is:
F = B × D = −cos ωt × sin (ωt−φ) (6)
It becomes.

Then, the adder 77 adds the first multiplication signal E and the second multiplication signal F, and the output signal G obtained as a result of the operation is
Output signal G = E + F = sinφ (7)
It becomes. That is, as shown in FIG. 2C, the output signal G of the adder 77 is sinφ with respect to the elapsed time t, and always depends on the phase difference φ of the rotation angle and is only a direct current component.

Next, the operation of the LPF circuit 57 will be described. Now, suppose that the signal A of the encoder 53 has a noise frequency component, for example
Noise frequency component = asinωnt (8)
Are superimposed. Here, a, ωn, and t represent the noise amplitude, the noise angular frequency, and the elapsed time, respectively.

Instead of sinωt in Equation 5, sinωt + asinωnt
And calculating the output signal Gn,
Output signal Gn = sinφ + a × {sin (ωnt + ωt−φ) + sin (ωnt−ωt + φ)}
It becomes.

  Therefore, the noise frequency component is converted into frequencies of ωnt + ωt and ωnt−ωt. Removing this noise frequency component by the LPF circuit 57 is synonymous with applying a bandpass filter (BPF) to the angular frequency of the signal A. The above description is for signal A, but the same is true for signal B.

  As described above, since the two-phase signal A and the signal B are converted into sinφ, and LPF is applied to the sinφ, the angle error due to the phase delay is smaller than the method of removing the noise by applying the LPF to the original signal. Reduced. That is, even if noise is superimposed on the two-phase sine wave signal, the phase delay can be suppressed and the position detection accuracy can be improved.

  Next, a rotation angle detection method will be described. FIG. 3 is a flowchart showing the processing procedure of the rotation angle detection method according to the present invention. In the rotation angle detection method for detecting the rotation angle, first, the A phase signal A of the encoder 53 connected to the rotor of the electric motor 52 is output (step S-1).

  Next, an A-phase signal C whose angular frequency is the same as the angular frequency of the signal A is output (step S-2).

  The signals A and C are input, the signal A is multiplied by the signal C, and a first multiplication signal E obtained as a result of the operation is output (step S-3).

  Similarly, a signal B having the same angular frequency as the signal A and having a phase different from that of the signal A by 90 degrees is output (step S-4).

  A signal D having the same angular frequency as that of the signal A and having a phase different from that of the signal C by 90 degrees is output (step S-5).

  The signal B and the signal D are input, the signal B is multiplied by the signal D, and a second multiplication signal F obtained as a result of the calculation is output (step S-6).

  Further, the first multiplication signal E and the second multiplication signal F are added, and a sin value G of the phase difference φ of the rotation angle obtained is output as a result of the calculation (step S-7).

  The harmonics superimposed on the sin value G of the phase difference φ are suppressed, and the sin value H of the phase difference φ in which noise is suppressed is output (step S-8).

The angular frequency ω _o of the cosine wave signal by the SIN / COS converter (A) 74 based on the position commander 54 is changed so that the sin value H of the phase difference φ of the rotation angle in which the harmonics are suppressed becomes zero. Thus, the rotation angle of the encoder 53 is calculated. That, sin value H of the phase difference φ of the rotation angle by the position command 54 and the encoder 53 is regulated to zero, the angular frequency omega _e of the sinusoidal signal encoder 53 is output, SIN / COS converter (A) The rotation angle of the encoder 53 can be calculated in accordance with the angular frequency ω _o of the cosine wave signal output by 74.

As apparent from the above description, in the embodiment of the present invention, the sine wave frequency of the encoder 53 is synchronized with the frequency f ₀ by the SIN / COS converter (A) 74. Thereby, even if noise is superimposed on the two-phase sine wave signal by the encoder, the phase delay can be suppressed, and the detection accuracy of the rotation angle can be improved.

  Next, a measuring device which is another embodiment of the rotation angle detecting device according to the present invention will be described. FIG. 4 is a control block diagram showing this detection apparatus. 4, elements having the same functions as those in FIG. 1 are denoted by the same reference numerals. FIG. 5 is an explanatory diagram for explaining the function of FIG. The functional element (A) 78 includes a PI circuit 58, an amplifier circuit 59, an electric motor 52, and an encoder 53.

  The measuring device 71B is a device that detects the amount of movement of a traveling long sheet (not shown, hereinafter referred to as a sheet), for example, a measuring roll (not shown) and a presser via the traveling sheet. The amount of movement of the sheet can be detected by pressing a roll (not shown) and the rotation angle of the rotation angle detector connected to the rotation axis (not shown) of the measurement roll, the diameter of the measurement roll, and the like. That is, as shown in FIG. 4, the measuring device 71B regards the position command device 54 as a measuring roll of the measuring device 71B and the SIN / COS converter (A) as a rotation angle detector, and relates to the present invention. By applying the rotation angle detection device 72, the rotation angle of the position commander 54 is detected from the output value K of the PI circuit 80, and the movement amount of the sheet is detected.

  As shown in FIG. 4, the measuring device 71 </ b> B includes a rotation angle detection device 72, an LPF circuit 57, and a functional element (B) 79. Since the rotation angle detection device 72 and the LPF circuit 57 have been described above, description thereof will be omitted. The functional element (B) 79 includes a PI circuit 58, a PI circuit 80, and a SIN / COS converter (B) 81. The functional element (B) 79 is equivalent to the functional element (A) 78 in FIG. As shown in FIG. 4, the PI circuit 58 inputs a sin value H of the phase difference φ of the rotation angle in which noise on the two-phase sine wave signal by the LPF circuit 57 is suppressed, and a sin value H of the phase difference φ. Are integrated with respect to time, and the rotational angular velocity I obtained as a result of the calculation is output to the PI circuit 80.

  The PI circuit 80 corresponds to the amplifier circuit 59 and the electric motor 52 in FIG. 5, receives the rotational angular velocity I, integrates the rotational angular velocity I over time, and converts the rotational angle K obtained as a result of the calculation into a SIN / COS converter (B ) 81.

The SIN / COS converter 81 is a converter that inputs the rotation angle K and outputs a two-phase sine wave signal (a signal corresponding to the signal A and the signal B) based on the rotation angle K. Even in this case, when the measuring device 71B is normally controlled, the angular frequency ω _e of the SIN / COS converter (B) 81 and the angular frequency ω _{o of} the SIN / COS converter (A) 74 are: It can be regarded as the same angular frequency ω instantaneously. Φ indicates a phase difference φ of the rotation angle between the signal from the SIN / COS converter (B) 81 and the signal from the SIN / COS converter (A) 74 based on the rotation angle of the measuring roll. The angular frequency ω _e of the SIN / COS converter (B) 81 is controlled so that the phase difference φ becomes zero, and the angular frequency at that time is regarded as the angular frequency of the SIN / COS converter (A) 74. That is, based on the angular frequency ω _e of the SIN / COS converter (B) 81, the rotation angle of the measuring roll can be obtained, and the movement amount of the sheet can be detected.

  In the above description, the present invention is applied to a rotary type connected to a rotary electric motor as an encoder connected to a moving body. However, the present invention can also be applied to a linear type connected to a linear motor, for example, a linear encoder. In that case, the rotation angle and the phase difference of the rotation angle in the text are read as linear displacement and linear displacement difference, respectively.

It is a control block diagram which shows the Example which applied the rotation angle detection apparatus which concerns on this invention to the electric motor control apparatus. It is a figure which shows the phase difference of the sine wave signal and rotation angle of an encoder with respect to the elapsed time in the rotation angle detection apparatus which concerns on this invention. It is a flowchart which shows the process sequence of the rotation angle detection method which concerns on this invention. It is a control block diagram which shows the other Example of the rotation angle detection apparatus which concerns on this invention. It is explanatory drawing for demonstrating the function of FIG. It is a general | schematic functional block diagram of the program performed in the conventional rotation angle detection apparatus. It is a control block diagram which shows the conventional rotation angle detection apparatus.

Explanation of symbols

10 Rotation angle detection device 14 CPU
DESCRIPTION OF SYMBOLS 16 Program 26 Signal processing part 32 Acceleration calculation part 34 Acceleration restriction part 36 Threshold correction part 38 Rotation angle calculation part 51 Electric motor control apparatus 52 Electric motor 53 Encoder 54 Position command device 55 Rotation angle detection apparatus 56 Subtractor 57 LPF circuit 58 PI circuit 59 Amplifier circuit 60 LPF circuit 61 LPF circuit 62 arctan (A / B) calculator 63 LPF circuit 71 Motor controller 72 Rotation angle detector 73 Phase difference detector 74 SIN / COS converter (A)
75 1st multiplier 76 2nd multiplier 77 Adder 78 Functional element (A)
79 Functional elements (B)
80 PI circuit 81 SIN / COS converter (B)
A Phase A sine wave signal of the encoder B Phase B sine wave signal of the encoder C Phase A cosine wave signal from the SIN / COS converter (A) D Phase B cosine wave signal from the SIN / COS converter (A)

Claims (5)

In the position detection device for detecting the position of the moving body based on the two-phase sine wave signals of the A phase and the B phase output from the encoder connected to the moving body,
A position commander for setting a target position of the moving body;
An A-phase sine wave signal output from the encoder, a B-phase sine wave signal whose phase differs from the A-phase sine wave signal by 90 degrees, an A-phase cosine wave oscillation signal based on the target position, and a phase Includes a phase difference detection means for inputting a B phase cosine wave oscillation signal different from the A phase cosine wave oscillation signal by 90 degrees and detecting a phase difference between the cosine wave oscillation signal and the sine wave signal. ,
The frequency and phase of the sine wave signal are made to coincide with the frequency and phase of the cosine wave oscillation signal so that the phase difference becomes zero, and the position of the moving body becomes the same as the target position. A position detecting device for detecting a position of a moving body. The phase difference detecting means includes
A SIN / COS converter that inputs the target position and converts the target position into the A-phase cosine wave oscillation signal and the B-phase cosine wave oscillation signal;
A first multiplier that inputs the A-phase sine wave signal and the A-phase cosine wave oscillation signal and outputs a first multiplication signal obtained by multiplying the signals;
A second multiplier that inputs the B-phase sine wave signal and the B-phase cosine wave oscillation signal and outputs a second multiplication signal obtained by multiplying the signals;
An adder for inputting the first multiplication signal and the second multiplication signal and outputting a phase difference between the sine wave signal and the cosine wave oscillation signal obtained by adding the signals;
The position detection device according to claim 1, further comprising:   The position detection apparatus according to claim 1, wherein the moving body is a rotor of an electric motor. In a position detection method for detecting the position of the moving body based on a two-phase sine wave signal of A phase and B phase output from an encoder connected to the moving body,
Detecting the A-phase sine wave signal out of the two-phase sine wave signals;
Detecting a B-phase sine wave signal whose phase differs from the A-phase sine wave signal by 90 degrees;
Generating an A-phase cosine wave oscillation signal that is synchronized with the frequency of the sine wave signal and that is based on the target position of the moving body;
Generating a B-phase cosine wave oscillation signal that is 90 degrees out of phase with the A-phase cosine wave oscillation signal;
Multiplying the A phase sine wave signal by the A phase cosine wave oscillation signal to generate a first multiplication signal;
Multiplying the B-phase sine wave signal by the B-phase cosine wave oscillation signal to generate a second multiplication signal;
Adding the first multiplication signal and the second multiplication signal to generate a phase difference between the cosine wave oscillation signal and the sine wave signal;
When the phase difference is controlled to be zero, the position of the moving body is detected by matching the target position with the position of the moving body.   The position detection method according to claim 6, wherein the moving body is a rotor of an electric motor.

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