Claims
- 1. A method of identifying mapping of a paper machine actuator in a paper making process, the method comprising
a) performing a mapping test to obtain a mapping test result, b) forming a non-linear shrinkage profile of the paper web, c) eliminating the effect of the non-linear shrinkage profile from the mapping test result, d) forming a straight line from the result obtained in step c), e) forming a first mapping model which does not include the effect of the non-linear shrinkage profile f) comparing the straight line formed in step d) with the mapping model formed in step e) to produce a first linear mapping error, g) forming a second mapping model utilizing the non-linear shrinkage profile, h) comparing the mapping model formed in step g) with the result of the mapping test to produce a second linear mapping error, i) forming the total error of linear errors from the difference between the first linear mapping error and the second linear mapping error, j) determining the magnitude allowed for the total error of linear errors, and k) comparing the magnitude of the total error of linear errors produced with the allowed magnitude of the total error of linear errors, and if the total error of linear errors is sufficiently small, concluding that the linear errors indicate a linear error in the mapping model, and that the currently used non-linear shrinkage profile indicates the non-linear shrinkage profile to be used in the mapping model with sufficient accuracy, in which case the linear error and non-linear shrinkage profile thus determined are used in the mapping model, and if the total error of linear errors is too great, forming a new non-linear shrinkage profile and repeating method steps c) to k).
- 2. A method according to claim 1, wherein in step c) the test result consists of test result points from which a straight line is formed in step d) to convert the set of test result points into a profile.
- 3. A method according to claim 1, wherein in step h) the test result consists of a set of test results from which an actuator resolution profile is formed by interpolating the values between the test results with linear interpolation.
- 4. A method according to claim 1, wherein in the initial situation the amplitude of the non-linear shrinkage profile is determined by a mapping test, in which case the amplitude is R′/R, where
R is the total linear shrinkage of the paper web, and R′ is the linear shrinkage that occurs between the excitation points of the mapping test.
- 5. A method according to claim 1, wherein the second mapping model has the formula
- 6. A method according to claim 1, further comprising forming a trapezoidal graph for the non-linear shrinkage profile and controlling the non-linear shrinkage profile by adjusting its amplitude and the location of the points of intersection.
- 7. A method according to claim 1, wherein the width of the paper web is measured by edge measuring devices for the linear total shrinkage of the mapping model.
- 8. A method according to claim 1, further comprising forming a parameter from the total error of linear errors by the method of least squares to obtain an estimate of the magnitude of the total error.
- 9. An apparatus for identifying mapping of a paper machine actuator, the apparatus comprising means for performing a mapping test to obtain a mapping test result,
means for forming a non-linear shrinkage profile of the paper web, means for eliminating the influence of the non-linear shrinkage profile from the mapping test result and means for forming a straight line from the result, means for forming a first mapping model without the effect of the non-linear shrinkage profile, means for comparing the straight line formed with the mapping model without the effect of the non-linear shrinkage profile, the means being arranged to produce a first linear mapping error, means for forming a second mapping model utilizing the non-linear shrinkage profile, means for comparing the mapping model that utilizes the non-linear shrinkage profile with the mapping test result, the means being arranged to produce a second linear mapping error, means for comparing the first linear mapping error with the second linear mapping error to produce the total error of linear errors, means for determining the magnitude allowed for the total error of linear errors, and means for comparing the magnitude of the total error of linear errors with the allowed magnitude, and, if the magnitude is sufficiently small, the linear mapping errors are arranged to form the linear error to be used in the mapping model and the currently used non-linear shrinkage profile is arranged to be used as the non-linear shrinkage profile in the mapping model with sufficient accuracy, and, if the total error of linear errors is too great, the apparatus is arranged to form a new non-linear shrinkage profile of the paper web and to determine a new total error of linear errors.
- 10. An apparatus according to claim 9, wherein that the second mapping model has the formula
- 11. An apparatus according to claim 9, wherein the graph for the non-linear shrinkage profile is trapezoidal and that the non-linear shrinkage profile is controlled by adjusting the amplitude and the location of the points of intersection.
- 12. An apparatus according to claim 9, wherein the apparatus comprises edge measuring devices for measuring the paper web width to determine the linear total shrinkage of the mapping model.
- 13. An apparatus according to claim 9, wherein the apparatus comprises means for determining a parameter from the total error of linear errors by the method of least squares to estimate the magnitude of the total error of linear errors.
Priority Claims (1)
Number |
Date |
Country |
Kind |
19992849 |
Dec 1999 |
FI |
|
Parent Case Info
[0001] This application is a continuation of International Application PCT/FI00/01157 filed Dec. 28, 2000, which designated the U.S. and was published under PCT Article 21 (2) in English.
Continuations (1)
|
Number |
Date |
Country |
Parent |
PCT/FI00/01157 |
Dec 2000 |
US |
Child |
10154066 |
May 2002 |
US |