Inspection method and inspection apparatus

• US 20060210141A1
• Filed: 03/15/2006
• Published: 09/21/2006
• Est. Priority Date: 03/16/2005
• Status: Abandoned Application

• Current Assignee: Omron Corporation
• Original Assignee: Omron Corporation
• Inventors: Tasaki, Hiroshi, Shimizu, Atsushi, Kojitani, Kazuto
• Application Number:
  US11/376,285
• Publication Number:
  US 20060210141A1
• Time in Patent Office: Days
• US Class Current: 382/141
• CPC Class Codes: G06F 18/2411 based on the proximity to a decision surface, e.g. support vector machines

Abstract

An inspection method and an inspection apparatus are disclosed, wherein the appropriate inspection can be conducted in accordance with the situation change of a nonconforming product from an initial stage, an adjust stage and a stable stage. The conformity/nonconformity is discriminated according to a MTS model and a one class SVM model based on the normal data obtained from a conforming product. The conformity/nonconformity is discriminated by both the MTS and the one class SVM in an adjust stage where a sufficient amount of sample data cannot be acquired or the shape of the conforming product distribution in the feature space and the shape of the normal area are unstable, and only by the MTS in a stable stage where a sufficient amount of sample data can be acquired and the shape of the conforming product distribution and the shape of the normal area are stable.

Claims

1. An inspection method for extracting the feature amount of the input measurement data and discriminating the conformity/nonconformity of an object to be inspected, based on the extracted feature amount, comprising the steps of:

discriminating the conformity/nonconformity of a product in accordance with a model based on the normality data obtained from a conforming product;

discriminating the conformity/nonconformity of a product based on the result of discrimination of the measurement data of the object to be inspected, according to both a parametric discrimination model and a nonparametric discrimination model in an adjust stage where a sufficient amount of sample data cannot be acquired or the conforming product distribution in the feature space is unstable and therefore the estimation accuracy of the shape of the normal area is not sufficient; and

discriminating the conformity/nonconformity of the product based only on the result of discrimination of the measurement data of the object to be inspected, according to the parametric discrimination model in a stable stage where a sufficient amount of sample data can be acquired and the conforming product distribution and the shape of the normal area is stable.

2. An inspection method according to claim 1,

wherein the transfer from the adjust stage to the stable stage is conducted in the case where the ratio of coincidence between the conformity/nonconformity discrimination result according to the nonparametric discrimination model and the conformity/nonconformity discrimination result according to the parametric discrimination model in the adjust stage is not less than a predetermined value.

3. An inspection method according to claim 1,

wherein in the case where the result of the conformity/nonconformity discrimination according to the parametric discrimination model and the result of the conformity/nonconformity discrimination according to the nonparametric discrimination model are different from each other in the adjust stage, the discrimination result by the human being is employed as the final result of the conformity/nonconformity discrimination for the measurement data of the object to be inspected.

4. An inspection method according to claim 1,

wherein the MTS is used as the parametric discrimination model and the one class SVM is used as the nonparametric discrimination model.

5. An inspection method for extracting the feature amount of the input measurement data and discriminating the conformity/nonconformity of an object to be inspected, based on the extracted feature amount, comprising the steps of:

discriminating the conformity/nonconformity of the product in accordance with a model based on the normality data obtained from a conforming product;

discriminating the conformity/nonconformity of the product based only on the result of discrimination of the measurement data of the object to be inspected, according to the nonparametric discrimination model in an initial stage where only a few sample data can be acquired and the conforming production distribution in the feature space and the shape of the normal cannot be estimated;

discriminating the conformity/nonconformity of the product based on the measurement data of the object to be inspected, according to both the parametric and nonparametric discrimination models, and determining the conformity/nonconformity of the product using the result of both the parametric and nonparametric discrimination models in an adjust stage where a sufficient amount of sample data cannot be acquired or the shape of the conforming product distribution in the feature space is unstable and the accuracy of estimation of the shape of the normal area is insufficient; and

discriminating the conformity/nonconformity of the product based on the measurement data of the object to be inspected, according to only the result of the parametric discrimination model in a stable stage where a sufficient amount of sample data can be acquired and the conforming product distribution and the shape of the normal area are stable.

6. An inspection method according to claim 5,

wherein the transfer from the initial stage to the adjust stage is conducted in the case where the number of samples collected is larger than at least the number of the feature amounts.

7. An inspection method according to claim 5,

wherein the transfer from the adjust stage to the stable stage is conducted in the case where the ratio of coincidence between the conformity/nonconformity discrimination result according to the nonparametric discrimination model and the conformity/nonconformity discrimination result according to the parametric discrimination model in the adjust stage is not less than a predetermined value.

8. An inspection method according to claim 5,

wherein in the case where the result of the conformity/nonconformity discrimination according to the parametric discrimination model and the result of the conformity/nonconformity discrimination according to the nonparametric discrimination model are different from each other in the adjust stage, the discrimination result by the human being is employed as the final result of the conformity/nonconformity discrimination for the measurement data of the object to be inspected.

9. An inspection method according to claim 5,

wherein the MTS is used as the parametric discrimination model and the one class SVM is used as the nonparametric discrimination model.

10. An inspection apparatus for extracting the feature amount of the input measurement data and discriminating the conformity/nonconformity of an object to be inspected, based on the extracted feature amount:

wherein the conformity/nonconformity discrimination is carried out in accordance with a model generated based on the normal measurement data obtained from a conforming product;

the apparatus further comprising the function of discriminating the conformity/nonconformity according to the parametric discrimination model and the function of discriminating the conformity/nonconformity according to the nonparametric discrimination model;

wherein the function of discriminating the conformity/nonconformity according to the parametric discrimination model and the function of discriminating the conformity/nonconformity according to the nonparametric discrimination model include a control device for controlling and permitting one of the functions to be executed alone or both of the functions to be executed at the same time;

the control device performing the control operation in such a manner that;

both the function of discriminating the conformity/nonconformity according to the parametric discrimination model and the function of discriminating the conformity/nonconformity according to the nonparametric discrimination model based on the measurement data of the object to be inspected are executed and the conformity/nonconformity is finally discriminated based on the discrimination results of the two functions in an adjust stage where a sufficient amount of sample data cannot be acquired or the shape of the conforming product distribution in the feature space is unstable so that the estimation accuracy of the shape of the normal area is not sufficient; and

the conformity/nonconformity is discriminated based only on the function of discriminating the conformity/nonconformity based on the measurement data of the object to be inspected, according to the parametric discrimination model in a stable stage where a sufficient amount of sample data can be acquired and the shape of the conforming product distribution and the shape of the normal area are stable.

11. An inspection apparatus according to claim 10,

wherein the control device includes the function of carrying out the conformity/nonconformity discrimination on the measurement data of an object to be inspected, based only on the nonparametric discrimination model in an initial stage where the sample data that can be acquired are not sufficient and the shape of the conforming product distribution in the feature space and the shape of the normal area cannot be estimated.

12. An inspection apparatus according to claim 10, further comprising a model generating device for generating a model for abnormality detection based on the normal measurement data obtained from a conforming product,

wherein the function of discriminating the conformity/nonconformity according to the parametric discrimination model and the function of discriminating the conformity/nonconformity according to the nonparametric discrimination model are executed based on the model generated by the model generating device.

13. An inspection apparatus according to claim 12,

wherein the normal measurement data used by the model generating device to generate a model includes the measurement data for the object to be inspected, determined as a conforming product.

14. An inspection apparatus according to claim 10, further comprising:

the function of displaying an input screen for receiving the input of the result of discrimination by the human being and the function of using the discrimination result input based on the input screen as the final conformity/nonconformity result for the measurement data of the object to be inspected, in the case where the conformity/nonconformity discrimination result according to the nonparametric discrimination model and the conformity/nonconformity discrimination result according to the parametric discrimination model are different from each other.

15. An inspection apparatus according to claim 10,

wherein the function of discriminating the conformity/nonconformity according to the parametric discrimination model uses the MTS and the function of discriminating the conformity/nonconformity according to the nonparametric discrimination model uses the one class SVM.