JP3201244B2 - Scan type sensor misalignment compensation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a running control device of a scan type sensor used in a paper machine control system and the like, and more particularly to an improvement capable of observing a fixed point even if a reciprocating speed fluctuates.

[0002]

2. Description of the Related Art In a paper machine, control is performed so that the quality of paper to be manufactured is equalized to a standard value. As disclosed in Japanese Patent Application Laid-Open No. 1-192892, the quality of paper is measured by reciprocally scanning a sensor for measuring basis weight, moisture content, paper thickness and the like in the paper width direction. At this time, the trajectory drawn on the paper on which the sensor is manufactured is zigzag, so that the measurement components are separated in the width direction and the flow direction of the paper. For example, in profile control of basis weight, an operating end called a slice bolt distributed in the paper width direction is opened and closed to manufacture paper having a uniform basis weight in the paper width direction. Therefore,
As disclosed in Japanese Patent Application Laid-Open No. 3-146784, an identification operation for determining which measurement position corresponds to a certain operation end is important in profile control.

[0003] It is necessary that the measurement position in the forward movement and the measurement position in the backward movement coincide with each other regardless of the scanning speed. Therefore, Japanese Patent Laid-Open No. 7-2090
No. 15, the forward F is independent of the scanning speed.
A time delay compensation calculation of a measurement system in which the peaks and valleys of the measured value distributions of the two substantially coincide with each other in the backward and backward B is proposed.

[0004]

However, in such displacement compensation, since the conversion is made into integers based on the running pulse of the sensor unit, there is a problem that a displacement due to a truncation error below the decimal point occurs. Was. FIG.
7A is an explanatory diagram of occurrence of a position shift, FIG. 7A is a measurement position pulse signal, FIG. 7B is an object to be measured, FIG.
(D) shows the forward direction of the high-speed scan, and (E) shows the reciprocation of the high-speed scan. Here, it is assumed that a measurement section is represented by and a measurement position pulse signal is generated at the center of each measurement section. It is assumed that the object to be measured has a delta function-like distribution near the boundary with the measurement section. In the low-speed scan, the position information and the sensor information are synchronized, and the measured value distributions of the forward F and the backward B substantially coincide with each other. However, in high-speed scanning, sensor information is delayed as compared with position information due to a sensor time constant and a system delay time. As a result, profile data may be displaced. Then, the measured value distributions of both the forward F and the backward B are shifted. Previously, the scan speed of the sensor was almost fixed at the recommended value, but the scan speed has been gradually increased in response to the request for improvement in measurement accuracy. There is a problem that causes inconvenience in profile control.

The present invention has been made to solve the above-mentioned problem, and provides a scan-type sensor in which a time delay compensation operation is performed in which the peaks and valleys of the measured value distributions of the forward F and the backward B substantially coincide with each other without depending on the scanning speed. An object of the present invention is to provide a position shift compensating device.

[0006]

In order to achieve the above object, the present invention provides a sensor unit 20 on which a sensor for measuring the basis weight, moisture content, and the like of a sheet 10 to be measured is mounted, and the sensor unit is mounted on the sheet to be measured. Sensor driving means 30 for reciprocating scanning in the width direction of the sheet, measurement position detection means 40 for generating a measurement position pulse signal in the width direction of the sensor unit, and measurement position pulse signal of the sensor unit output from the measurement position detection means And a sensor signal processing unit 50 for inputting the measurement signal from the sensor unit accommodated in the sensor unit and having the following configuration.

The reciprocating correction pulse number calculating section 60 calculates the number of pulses NpulseW to be corrected in reciprocation using the delay time χ of the sensor housed in the sensor unit and the time interval Tpulse of the measurement position pulse signal as follows. NpulseW = Round [2χ / Tpulse] (1)

[0008] The position correction pulse number calculation unit 70 calculates the forward correction pulse number NpulseF when the traveling direction of the sensor unit is forward with respect to the number of reciprocation correction pulses obtained by the reciprocation correction pulse number calculation unit. The number NpulseB of retreat correction pulses when the traveling direction of the sensor unit is retreat is calculated by the following rounding calculation. NpulseF = Round [NpulseW / 2] (2) NpulseB = Int [NpulseW / 2] (3)

[0009] The sensor signal processing means is characterized in that the measurement signal of the sensor housed in the sensor unit is fetched by using the measurement position pulse signal corrected by the position correction pulse number calculating section.

A sensor is mounted on the sensor unit, and reciprocating scanning of forward and backward is performed by a sensor driving means. Then, the measurement position pulse signal is output by the measurement position detection means. The reciprocation correction pulse number calculation unit divides the time delay of the sensor by the measurement position pulse signal to determine the amount of correction in reciprocation, and then determines the number of position correction pulse numbers. The calculation unit distributes the data to forward F and backward B. At this time, the rounding off operation after the decimal point and the rounding off operation after the decimal point are combined, so that the reciprocating correction amount is made in units of one measurement position pulse signal.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a configuration block diagram showing one embodiment of the present invention. In the figure, a sheet to be measured 10 is a sheet-like object such as a paper or a plastic sheet and has a uniform composition. The sensor unit 20 includes the sheet 10 to be measured.
A reciprocating scan is performed in the width direction, and a sensor is mounted for measuring the characteristics of the sheet 10 to be measured. For example, in the case of paper, the basis weight, moisture content, paper thickness, gloss, and the like are used. In the case of a plastic sheet, the basis weight, sheet thickness, tear strength, and the like are used. The sensor driving device 30 causes the sensor unit 20 to reciprocate in the width direction of the sheet 10 to be measured. It has a sensor base for scanning and a control unit for controlling the travel of the sensor base. The measurement position detection unit 40 generates a reference signal of a measurement position in the width direction of the sensor unit 20. For example, the measurement unit is divided into N points at equal intervals in the width direction, and the center of the divided zone is set as a measurement reference position. Outputs a pulse signal. The pulse output may be configured to generate a pulse when the sensor base on which the sensor unit 20 is mounted passes, for example, a reference position set on the frame.

The sensor signal processing unit 50 receives the reference signal of the measurement position output from the measurement position detection unit 40 and makes it correspond to the measurement signal of each sensor housed in the sensor unit 20. The reciprocating correction pulse number calculating unit 60 calculates the delay time of the sensor housed in the sensor unit χ [millisecond] and the time interval Tpulse of the measurement position pulse signal.
Using [milliseconds], the number of pulses Npu to be corrected in a round trip
NseW = Round [2χ / Tpulse] (1) Here, “Round” refers to an operation of rounding off the decimal point.

For the number of reciprocating correction pulses calculated by the reciprocating correction pulse number calculating section, the position correction pulse number calculating section 70 calculates the number NpulseF of forward correction pulses when the traveling direction of the sensor unit is forward, to the next decimal point. The number NpulseB of retreat correction pulses when the traveling direction of the sensor unit is retreat is calculated by the following rounding calculation. NpulseF = Round [NpulseW / 2] (2) NpulseB = Int [NpulseW / 2] (3) Here, “Int” refers to a calculation for rounding down decimal places.

The operation of the thus configured device will be described. FIG. 2 is a diagram showing the relationship between the running pulse signal and the measurement reference position. In the figure, when the sensor unit 20 scans in the width direction of the sheet 10 to be measured, a measurement position pulse signal is output from the measurement position detection unit 40 to the sensor signal processing unit 50. Here, the measurement position pulse signal is output at the same point in the width direction regardless of whether the traveling direction of the sensor unit 20 is forward F or backward B.

According to the reciprocating correction pulse number calculating section 60 and the position correcting pulse number calculating section 70, when the reciprocating correction pulse number NpulseW is 5, the forward correction pulse number Npul
The seF is 3 and the number NpulseB of the backward correction pulse is 2
Individual. On the other hand, the conventional formula for calculating the number of correction pulses is as follows. Npulse = Int [χ / Tpulse] (4) That is, the same number of correction pulses obtained for one side is used in both directions. Thus, the number of corrections is always twice the number of corrections on one side, and the accuracy of the pulses used for correction is an even multiple of the pulse pitch, and the accuracy is insufficient. In the above example, the forward correction pulse number NpulseF and the backward correction pulse number NpulseB are the same two.

[0016]

FIG. 3 is an explanatory view of profile data using a correction pulse calculation. FIG. 3A shows a conventional correction pulse calculation by the formula (4), and FIG. 3B shows a correction pulse by the formulas (1) to (3). This shows a case where an operation is used. The pulse interval of the measurement position pulse signal is 17.5 [mm], and the moving speed of the head is 7.0 [m /
Min.], Total scan width 800 [mm], sensor time constant is 8
0 [milliseconds]. Using equation (4), the forward correction pulse number NpulseF and the backward correction pulse number NpulseB
Are the same two, the displacement between the forward F and backward B positions is about 30
[Mm]. On the other hand, when the correction pulse calculation by the equations (1) to (3) is used, the number of round-trip correction pulses Npu
When lseW is 5, the forward correction pulse number NpulseF is 3
, And the number NpulseB of retreat correction pulses is two. Therefore, the deviation between the forward F and the backward B position is about 15 [mm].
And halved.

[0017]

As described above, the reciprocating correction pulse number calculation unit 60 and the position correction pulse number calculation unit 70
Forward correction pulse number NpulseF and reverse correction pulse number Np
ulseB can be displaced, and the reciprocal displacement is absorbed up to one pitch of the measurement position pulse signal. Therefore, the effects of the delay of the response of the measurement system and the change in the traveling speed are removed. There is an effect that the peaks and valleys of the profile can be matched regardless of whether the traveling direction of the sensor is forward or backward.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram showing one embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship between a traveling pulse signal and a measurement reference position.

FIG. 3 is an explanatory diagram of profile data using correction pulse calculation.

FIG. 4 is an explanatory diagram of occurrence of a displacement.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Sheet to be measured 20 Sensor unit 30 Sensor driving device 40 Measurement position detection part 50 Sensor signal processing part 60 Reciprocation correction pulse number calculation part 70 Position correction pulse number calculation part

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01D 3/028 D21F 7 / 00,7 / 06 G01G 17/02

Claims (1)

(57) [Claims] 1. A sensor unit (20) on which a sensor for measuring the basis weight, moisture content, etc. of a sheet to be measured (10) is mounted.
A sensor driving unit (30) for reciprocally scanning the sensor unit in the width direction of the sheet to be measured, a measurement position detecting unit (40) for generating a measurement position pulse signal in the width direction of the sensor unit, A scan type sensor having a sensor signal processing means (50) for inputting a measurement position pulse signal of the sensor unit output from the position detection means and for making the measurement signal of the sensor housed in the sensor unit correspond thereto; The delay time (χ) of the accommodated sensor and the time interval (Tpuls
Number of pulses to be corrected in round trip using e) (NpulseW)
And the number of round-trip correction pulses calculated by the following rounding operation to the decimal point: (60) NpulseW = Round [2puls / Tpulse] When the traveling direction of the sensor unit is forward, the number of forward correction pulses (NpulseF) is calculated by the following rounding operation after the decimal point, and when the traveling direction of the sensor unit is backward, the number of reverse correction pulses (Npu
(70), and NpulseF = Round [NpulseW / 2] (2) NpulseB = Int [NpulseW / 2] (3) A position error compensating device for a scan-type sensor, wherein the signal processing means uses a measurement position pulse signal corrected by the position correction pulse number calculation unit to capture a measurement signal of a sensor housed in the sensor unit.