Method for controlling the quality of industrial processes and system therefrom

• US 7,640,125 B2
• Filed: 03/16/2005
• Issued: 12/29/2009
• Est. Priority Date: 03/16/2004
• Status: Expired due to Fees

• Current Assignee: C.R.F. Societa Consortile Per Azioni
• Original Assignee: Cefla Societa' Cooperativa
• Inventors: Terreno, Andrea, Pasquettaz, Giorgio, D'Angelo, Giuseppe
• Primary Examiner(s): Barbee; Manuel L
• Application Number:
  US11/080,519
• Publication Number:
  US 20050205528A1
• Time in Patent Office: 1,749 Days
• Field of Search: 702 81- 84, 702/108, 702/127, 219/109, 219/110, 700 32- 34, 700108-111, 340/3.1, 340/3.3, 340/3.42, 340/3.43, 340/3.44
• US Class Current: 702/81
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 31/125 Weld quality monitoring
• CPC Class Codes: G05B 19/41875 characterised by quality surveillance of production
• CPC Class Codes: G05B 2219/32186 Teaching inspection data, pictures and criteria and apply them for inspection
• CPC Class Codes: G05B 2219/45138 Laser welding
• CPC Class Codes: G05B 23/0221 Preprocessing measurements, e.g. data collection rate adjustment; Standardization of measurements; Time series or signal analysis, e.g. frequency analysis or wavelets; Trustworthiness of measurements; Indexes therefor; Measurements using easily measured parameters to estimate parameters difficult to measure; Virtual sensor creation; De-noising; Sensor fusion; Unconventional preprocessing inherently present in specific fault detection methods like PCA-based methods
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A method for controlling the quality of industrial processes, of the type comprising the steps of: making available one or more reference signals relating to the industrial process acquiring one or more real signals, indicative of the quality of said industrial process, comparing said one or more reference signal to said one or more real signals to identify defects in said industrial process. Said method further includes the operations of: obtaining a real part and an imaginary part from said reference signal; obtaining a real part and an imaginary part from said real signal; computing said real part first comparison dimensions between and said imaginary part from said reference signal; computing second comparison dimensions between said real part and said imaginary part from said real signal; comparing said first comparison dimensions and second comparison dimensions to obtain time location information associated to the presence of defects.

Claims

1. A method for controlling the quality of an industrial process, of the type comprising the steps of:

making available one or more reference signals relating to the industrial process;

acquiring one or more real signals, indicative of the quality of said industrial process;

comparing, using a processing unit, said one or more reference signal to said one or more real signals to identify defects in said industrial process, said comparing operation including;

obtaining a real part and an imaginary part from said reference signal; and

obtaining a real part and an imaginary part from said real signal;

wherein said comparing operation further comprises the operations of;

computing first comparison quantities by performing a comparison between values of said real part and of said imaginary part from said reference signal;

computing second comparison quantities by performing a comparison between values of said real part and of said imaginary part from said real signal; and

comparing said first comparison quantities and said second comparison quantities to obtain time location information associated to the presence of defects.

2. A method as claimed in claim 1, wherein said step of computing the first comparison quantities comprises a step of computing a reference phase and corresponding first angular coefficients of said reference phase and said step of computing the second comparison quantities comprises a step of computing a real phase and corresponding second angular coefficients of said real phase,

said operation of comparing said first comparison quantities and second comparison quantities comprising the comparison of said first angular coefficients and second angular coefficients to identify a time window for locating a frequency defect.

3. A method as claimed in claim 2, wherein said first angular coefficients comprise a mean valve value of the angular coefficient of the reference signal.

4. A method as claimed in claim 2, wherein said step of computing the first comparison quantities comprises a step of computing a reference cumulative area and said step of computing the- second comparison quantities comprises a step of computing a cumulative area of the real signal.

5. A method as claimed in claim 4, wherein it further comprises a step of evaluating a variation amplitude of said cumulative reference area in said time window, a step of evaluating a variation amplitude of said cumulative reference area of the real signal in said time window to evaluate an amplitude defect.

6. A method as claimed in claim 4, wherein said cumulative areas computed as the absolute value of the difference between the respective imaginary parts and real parts.

7. A method as claimed in claim 1, wherein said operations of obtaining a real part and an imaginary part from said reference signal and of obtaining a real part and an imaginary part from said real signal are obtained by means of a Hilbert transform.

8. A method as claimed in claim 1, wherein said industrial process is a laser welding process.

9. A system for controlling the quality industrial process, comprising:

sensor means for measuring one or more process parameters,

an electronic control and processing unit for processing the signals emitted by said sensor means,

wherein;

said electronic control and processing unit to process the signals emitted by said sensor means implements the method for controlling the quality of an industrial process as claimed in claim 1.