Process and device to continuously and in real time control a complex manufacturing process

• US 5,668,741 A
• Filed: 10/24/1996
• Issued: 09/16/1997
• Est. Priority Date: 11/26/1992
• Status: Expired due to Fees

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Prigent, Thierry
• Primary Examiner(s): Voeltz, Emanuel T.
• Assistant Examiner(s): KEMPER, MELANIE A
• Application Number:
  US08/736,306
• Time in Patent Office: 327 Days
• Field of Search: 364/551.01, 364/551.02, 364/552, 364/508, 364/572, 364/576, 364/550, 364/185, 364/186, 364/468.15, 364/468.16, 364/468.17, 364/474.11 , 364/474.16, 364/474.17, 364/474.19
• US Class Current: 702/182
• CPC Class Codes: G05B 2223/06 Remote monitoring
• CPC Class Codes: G05B 23/0237 based on parallel systems, e.g. comparing signals produced at the same time by same type systems and detect faulty ones by noticing differences among their responses
• CPC Class Codes: G07C 3/00 Registering or indicating the condition or the working of machines or other apparatus, other than vehicles

Abstract

The invention relates to the continuous monitoring of a manufacturing process. Channels continuously inspect fundamental elements of the manufacturing process in order to detect any changes in the products or machine. The data is processed in each channel by frequency estimators and then analyzed in order to detect major variations and to trigger an alarm signal. A monitor analyzes the various alarm signals to correlate them with expected changes in order to accept these alarms and to record the state of the manufacturing process when the alarms relate to aberrant phenomena.

Claims

1. A method for continuously monitoring a complex manufacturing process of a material being transformed through a plurality of steps during a predetermined time period, in order to apprehend, in a continuous and complete manner, a transient or perturbing phenomena occurring during the manufacturing process, the method comprising the steps of:

disposing fundamental elements in separate channels situated in the immediate vicinity of a machine so that each fundamental element is continuously monitored by a sensor and connected to at least one remote work station, through a local network;

translating, within each channel in the immediate vicinity of the sensor, a fundamental element into an analog signal by means of a sensor fixed to the machine;

making, within each channel in the mediate vicinity of the sensor, the analog signal discrete with a frequency determined in relationship to the fundamental element associated with the channel in order to obtain a succession of digital values representing the instantaneous values of the analog signal as a function of the time;

storing, within each channel in the immediate vicinity of the sensor, the digital values corresponding to the analog signal in the form of series of N values, said digital values being accessible during the predetermined time period;

processing, within each channel in the immediate vicinity of the sensor, a preceding series of M digital values where M>

N, the processing of the preceding series of M digital values being carried out by the use of spectral estimation techniques making it possible to transform the signal variations with respect to time into values which are a function of the frequency, and then storing the values which are a function of the frequency;

analyzing, within each channel in the immediate vicinity of the sensor, the values which are a function of the frequency in order to obtain objective characteristics depending on the series of M digital values processed and the number of characteristics of which is less than N;

continuously storing, within each channel in the immediate vicinity of the sensor, the objective characteristics;

comparing, within each channel in the immediate vicinity of the sensor, the objective characteristics corresponding to the series of M digital values either with given values or with the objective characteristics corresponding to one or more of the preceding series so as to provide a result of the comparison;

transmitting, within each channel in the immediate vicinity of the sensor, the result of the comparison over the local network;

receiving, at the remote work station, the result of the comparison for each channel for the purpose of observation and use in real time with optionally storing of the results of the various comparisons in each channel, the objective characteristics, and the series of N digital values so as to be able to carry out subsequently an analysis in delayed time over all the fundamental elements of the complex process; and

transferring, upon reception of an abnormal result of the comparison from any of the channels, from each of the channels to the remote work station the digital values stored during the predetermined time period and representing the instantaneous state of the fundamental elements as a function of time in order to time correlate each signal having occurred at the time the material experienced the fundamental element monitored by the respective sensor.

2. The method according to claim 1 characterized in that the spectral estimation techniques use the Fourier transform.

3. The method according to claim 2, further comprising the step of filtering the values of the samples processed by means of a Hanning window.

4. The method according claim 2, further comprising the step of filtering the values of the samples processed by means of a Blackman window.

5. The method according to claim 1, further comprising the step of filtering the values of the samples processed by means of a Hanning window.

6. The method according claim 1, further comprising the step of filtering the values of the samples processed by means of a Blackman window.

7. Equipment for the continuous monitoring of a complex manufacturing process of a material being transformed through a plurality of steps, during a predetermined time period, in order to apprehend, continuously and completely, transient or perturbing phenomena occurring during this process, process equipment comprising:

a) at least one remote work station designed to receive signals in real time making it possible to analyze or observe the state of the manufacturing process;

b) a local network designed to convey information to the remote work station;

c) a plurality of channels each associated with a fundamental element of the manufacturing process, each channel comprising;

1) a sensor enabling the fundamental element associated with it to be monitored continuously and continuously transforming the state of the fundamental element into an analog signal, the channels being disposed in the immediate vicinity of the sensor;

2) an analog-to-digital converter situated in the immediate vicinity of the sensor and receiving the analog signal in order to transform the analog signal into a succession of digital values representing the instantaneous state of the fundamental element as a function of time;

3) a signal processing device for simultaneously storing the succession of the digital values, during the predetermined time period, in the form of a series of N values and processing the digital values corresponding to a preceding series of M digital values for the purpose of transforming the time-dependent variations represented by the succession of M digital values into signals representing the frequency-dependent variations of the analog signal, and then, after processing, storing the signals representing the frequency-dependent variations;

4) an analyzer receiving the signals representing the frequency-dependent variations in order to transform them into a limited number, less than N, of objective characteristics;

5) a memory for continuously storing the objective characteristics corresponding to a given number of series of M digital values; and

6) means for comparing the objective characteristics either with given values or with the objective characteristics corresponding to one or more series of M previous signals so as to provide a result of the comparison and transmit the result over the local network; and

d) means at the remote work station to detect an abnormal result of the comparison so that, upon reception of the abnormal result of the comparison, the digital values stored during the predetermined time period and representing the instantaneous state of the fundamental elements as a function of time of each of the channels is transferred to the remote work station to time correlate each signal having occurred at the time the material experienced the fundamental element monitored by the respective sensor.

8. Equipment according to claim 7, characterized in that the signal processing device transforming the time-dependent variations into frequency-dependent variations comprises means for obtaining a discrete Fourier transform.

9. Equipment according to claim 8, characterized in that the signal processing device transforming the time-dependent variations into frequency-dependent variations comprises means for altering the series of M successive digital values of samples, either according to a Blackman function or according to a Hanning function.

10. Equipment according to claim 7, characterized in that the signal processing device transforming the time-dependent variations into frequency-dependent variations comprises means for altering the series of M successive values of samples, either according to a Blackman function or according to a Hanning function.