CA1218744A - System for operational monitoring of a machine - Google Patents
System for operational monitoring of a machineInfo
- Publication number
- CA1218744A CA1218744A CA000472768A CA472768A CA1218744A CA 1218744 A CA1218744 A CA 1218744A CA 000472768 A CA000472768 A CA 000472768A CA 472768 A CA472768 A CA 472768A CA 1218744 A CA1218744 A CA 1218744A
- Authority
- CA
- Canada
- Prior art keywords
- machine
- data processing
- time series
- vibration
- central monitoring
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Abstract
ABSTRACT
A system for machine condition monitoring through vibration analysis.
At least one vibration sensor (9), amplifying and digitizing means (7) and a microprocessor with asso-ciated memory (18) are combined into a local initial data processing unit disposed adjacent to the machine for forming and storing vibration data in the form of time series. These time series are periodically trans-ferred via remote communication means (17,15,14) to a control monitoring unit (1) for further processing of the time series. For this purpose, the control monitoring unit (1) includes frequency analysis means (22), pattern recognition means (23) and associated computer equipment.
Hereby, each local initial data processing unit can be operated without human surveyance.
A system for machine condition monitoring through vibration analysis.
At least one vibration sensor (9), amplifying and digitizing means (7) and a microprocessor with asso-ciated memory (18) are combined into a local initial data processing unit disposed adjacent to the machine for forming and storing vibration data in the form of time series. These time series are periodically trans-ferred via remote communication means (17,15,14) to a control monitoring unit (1) for further processing of the time series. For this purpose, the control monitoring unit (1) includes frequency analysis means (22), pattern recognition means (23) and associated computer equipment.
Hereby, each local initial data processing unit can be operated without human surveyance.
Description
~Z18744 .. 1 System for Operational Monitorin~ of a Machine.
TECHNICAL FIELD
The present invention relates to a system for operational monitoring of a machine.
PRIOR ART
Xnown systems for operational monitoring of a machine in-clude a frequency analyzer which is connected to a vibra-tion sensor mounted at the machine and comprises pattern recognition means capable of interpreting frequency spectra in relation to previously obtained rrequency spectra being representative of normal operational conditions as well as of deviations therefrom. However, the need for qualified personnelbeingavailable to handle the frequency analyzer at the machine is a disadvantage which makes the system much too expensive in many applications.
5UMMARY OF THE INVENTION.
The invention relates to a systemforoperational monitoring of a machine, wherein the known system has been improved in such a way that the need for qualified personnel,tohandle ~5 the frequency analyzer at the machine has been eliminated and, therefore, the number of applications can be increased considerably. ~n the system according to the invention the vibration sensor or sensors, amplifying and digitizing means and a microproce~ssoOE with associated memory are combined into a local, initial data processing unit disposed adjacent to said machine for forming and storing vibration data in the form of time series, whereas the frequenzy analyzer, the pattern recognition means and associated computer equipment are disposed in a central monitoring unit for further processingof said time series, remote communica-tion means being adapted to periodically transfer the time series from the initial data processing unit to the central monitoring unit.
S17~4 la More specifically, the invention provides in a system adapted for monitoring the condition of a machine by vibration analysis, and wherein the machine has a characteristic frequency spectrum when operating normally, said system including at least one vibration sensor in operative contact with said machine for sensing machine vibrations, and providing a vibration signal at its output, sampling means connected to the output of said vibration sensor, said sampling means including an amplifier, a low pass filter postcoupled to said amplifier, and an A/D
converter postcoupled to said filter for sampling, amplifying and digiti~ing the signal obtained from said vibration sensor, separate frequency analysis means arranged to receive the sampled and digitized signal from said sampling means for frequency analysis thereof, and pattern recognition means coupled to said frequency analysis means for detection of any abnormal frequency spectra correspoding to abnormal machine operation, the improvement comprising local data processing means near said machine adapted to store programs for -the control thereof, being connected to said vibration sensor, and including a microcomputer inclusive of a random access memory, being arranged for obtaining vibration data from said sensor, and for storing said vibration data in the form of a time series in said memory, said local data processing means also including said sampling means, central monitoring means remote from said local data processing means adapted to store another program therein, and providing for monitoring and further processing of said time series, said central monitoring means including computer means, as well as said frequency analysis means~
and said pattern recognition means, said computer means being connected to said frequency analysis means, control means connected to said central monitoring means, and a two-way communication link connecting said local data lZ1874~
lb processing means and said central monitoring means for periodic transmission of said time series from said memory in said microcomputer of said local data processing means in one direction to said frequency analysis means in said central monitoring means, and for transferring said other program from said central monitoring means back to said local data processing means in a direction opposite to said one direction, said control means providing for control of said amplifier, of said low pass filter, and of said A/D
converter, through said communication link, whereby transmission of said time series from said local data processing means to said central monitoring means can be matched to reception conditions prevailing at said central monitoring means.
7~9~
BRIEF DESCRIPTION OF THE DRAWING.
The drawing .figure shows a block diagram of a preferred embodiment of the system according to the invention.
s DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT.
In the preferred embodiment of the system according to the invention, a central monitoring unit 1 comprises a pa-ttern recognition equipment 2, the input 3 of which is connected to a frequency analyzer 4 having an input 5 connected via a first telecommunication channel 6 to a sampling device 7 provided with a control input 8 and connected to a vibration sensor 9 mounted on a machine (not shown) to be monitored. An output 10 of the pattern recognition equipment 2 serves to signal when the frequency spectra obtained from the frequency analyzer 4 comprises patterns representing deviations from a normal operational condition of the machine. Thus, the output 10 is connected to a control device 11 having an output 12 connected via a second telecommunication channel 13 to the control input 8 of the sampling device 7. Measurement information from the vibration sensor 9 will be transmitted in response to control information transmitted from the control device 11 and a terminal equipment 14 is arranged so as to establish periodically a two-way telecommunication connection 15 in-cluding said first and second telecommunication channels 6 and 13.
In the example, the telecommunication connection 15 is a part of the worldwide public telephone net-work and com-prises a relay station in the form of a g~o~tationary satellite.
The terminal equipment 14 consists of a modem and is pro-vided with an automatic dialling input 16 connected to a second output of the control device 11. Via the telecommu-nication connection 15, the terminal equipment 14 is connect-ed t-o-a c~rresponding terminal-equipment 17 c~nnected to the sampling device 7 and consisting of a modem having ~874g~
auto-reply facilities. Consequently, the monitored machine may belong to a plant which is remotely located (e.g. an oil field), movable (e.g. a ship) and possibly fully automatic (hydroelectric power station). The costs of the components o the inventive system can be kept low as regards the com-ponents assembled locally at the plant including the machine to be monitored. It is reasonable to assume that the plant is connected to the public telephone net-work in such a way that the terminal eq~ipment 17 is operative at regular time intervals while being conrolled by the control device 11 via the terminal equipment 14 in the central monitoring unit 1.
In the preferred embodiment, the terminal equipment 17 is connected to the sampling device 7 via a communication equipment 18 built around a microprocessor provided with a RAM for programs and data and arranged to be charged with programs via a serial port. The sampling device 7 comprises a charge amplifier 1~ and an A/D converter ?O serving to connect the vibration sensor 9 to the communication equipment 18. The latter is arranged to adjust the gain of the charge amplifier 19 via the control input 8 of the sampling means 7, and additionally tocontrol the A/D converter 0. For example, the vibration sensor may be supplemented by several vibra-tion sensors each being connected via an associated charge amplifier to a separate analog input of the A/D converter 20 addressed from the communication equipment 18 while being - controlled by a program stored in its RAM and obtained from a communication equipment ? 1 arranged in the central moni-toring unit 1 and likewise including a microprocessor. This program generates a time series which is stored in the RAM
of the communication equipment 18 and is transmitted after completed sampling to the communication equipment 21 via the telecommunication connection 15. The transmission of the time series may be repeated in case of detected faults, e.g. by using check sums. In addition to programs for sampling, the communication equipment 18 may also receive test programs form the communication equipment 21 for checking the opera-tion of e.g. the charge amplifier 19 and the vibration 1211!~7~4 sensor 9. Before the measuring signal is digitized , it is Eiltered in an antialising filter, i.a. a low pass filter having a steeply declining response characteristic in t~high frequency region. The upper limit frequency can be set from the control monitoring unit 1, depending on the frequency range being currently examined.
In the communication equipment 21 located in the central monitoring unit 1, the microprocessor is provided with programs for further processing of the received time series, i.a. by correcting the measuring values in view of the adjusted gain of the charge amplifier 19, and for conveying the results to the frequency analyzer ~. The latter includes a FFT (Fast Fourier Transform) frequency analyzer 22 having an output connected to a microprocessor 23 provided with a program for processing frequency spectra obtained from a frequency analyzer 22 and forming a table containing levels and frequencies for further processing in the pattern recognition equipment 2.
In the preferred embodiment, the pattern recognition equipment 2 comprises a computer provided with the recog-nition program SIMCA which was originally developed for the processing of chemical spectra of organic substances obtained by means of mass spectroscopes and gas chromato-- graphs ~World, S., et al, Proc. of Symposium on Applied Statistics, Copenhagen, January 22, 1981). In the inventive system, this program has been adjusted for the processing of frequency spectra of machine vibrations. In the course of normal operation of the machine a reference class of frequency spectra is generated and is later compared with each subsequent frequency spectrum. Under normal conditions, it is not necessary to interpret the frequency spectra.
The program calculates for every new frequency spectrum the probability that this spectrum belongs to a class different from the reference class. Should this probability - - -7~
be high, the deviating components in the frequency spectrum can be shown and a diagnosis of the operating condition be made. The result can be presented by means of a printer 24' connected to the pattern recognition equipment 2.
,.
:
TECHNICAL FIELD
The present invention relates to a system for operational monitoring of a machine.
PRIOR ART
Xnown systems for operational monitoring of a machine in-clude a frequency analyzer which is connected to a vibra-tion sensor mounted at the machine and comprises pattern recognition means capable of interpreting frequency spectra in relation to previously obtained rrequency spectra being representative of normal operational conditions as well as of deviations therefrom. However, the need for qualified personnelbeingavailable to handle the frequency analyzer at the machine is a disadvantage which makes the system much too expensive in many applications.
5UMMARY OF THE INVENTION.
The invention relates to a systemforoperational monitoring of a machine, wherein the known system has been improved in such a way that the need for qualified personnel,tohandle ~5 the frequency analyzer at the machine has been eliminated and, therefore, the number of applications can be increased considerably. ~n the system according to the invention the vibration sensor or sensors, amplifying and digitizing means and a microproce~ssoOE with associated memory are combined into a local, initial data processing unit disposed adjacent to said machine for forming and storing vibration data in the form of time series, whereas the frequenzy analyzer, the pattern recognition means and associated computer equipment are disposed in a central monitoring unit for further processingof said time series, remote communica-tion means being adapted to periodically transfer the time series from the initial data processing unit to the central monitoring unit.
S17~4 la More specifically, the invention provides in a system adapted for monitoring the condition of a machine by vibration analysis, and wherein the machine has a characteristic frequency spectrum when operating normally, said system including at least one vibration sensor in operative contact with said machine for sensing machine vibrations, and providing a vibration signal at its output, sampling means connected to the output of said vibration sensor, said sampling means including an amplifier, a low pass filter postcoupled to said amplifier, and an A/D
converter postcoupled to said filter for sampling, amplifying and digiti~ing the signal obtained from said vibration sensor, separate frequency analysis means arranged to receive the sampled and digitized signal from said sampling means for frequency analysis thereof, and pattern recognition means coupled to said frequency analysis means for detection of any abnormal frequency spectra correspoding to abnormal machine operation, the improvement comprising local data processing means near said machine adapted to store programs for -the control thereof, being connected to said vibration sensor, and including a microcomputer inclusive of a random access memory, being arranged for obtaining vibration data from said sensor, and for storing said vibration data in the form of a time series in said memory, said local data processing means also including said sampling means, central monitoring means remote from said local data processing means adapted to store another program therein, and providing for monitoring and further processing of said time series, said central monitoring means including computer means, as well as said frequency analysis means~
and said pattern recognition means, said computer means being connected to said frequency analysis means, control means connected to said central monitoring means, and a two-way communication link connecting said local data lZ1874~
lb processing means and said central monitoring means for periodic transmission of said time series from said memory in said microcomputer of said local data processing means in one direction to said frequency analysis means in said central monitoring means, and for transferring said other program from said central monitoring means back to said local data processing means in a direction opposite to said one direction, said control means providing for control of said amplifier, of said low pass filter, and of said A/D
converter, through said communication link, whereby transmission of said time series from said local data processing means to said central monitoring means can be matched to reception conditions prevailing at said central monitoring means.
7~9~
BRIEF DESCRIPTION OF THE DRAWING.
The drawing .figure shows a block diagram of a preferred embodiment of the system according to the invention.
s DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT.
In the preferred embodiment of the system according to the invention, a central monitoring unit 1 comprises a pa-ttern recognition equipment 2, the input 3 of which is connected to a frequency analyzer 4 having an input 5 connected via a first telecommunication channel 6 to a sampling device 7 provided with a control input 8 and connected to a vibration sensor 9 mounted on a machine (not shown) to be monitored. An output 10 of the pattern recognition equipment 2 serves to signal when the frequency spectra obtained from the frequency analyzer 4 comprises patterns representing deviations from a normal operational condition of the machine. Thus, the output 10 is connected to a control device 11 having an output 12 connected via a second telecommunication channel 13 to the control input 8 of the sampling device 7. Measurement information from the vibration sensor 9 will be transmitted in response to control information transmitted from the control device 11 and a terminal equipment 14 is arranged so as to establish periodically a two-way telecommunication connection 15 in-cluding said first and second telecommunication channels 6 and 13.
In the example, the telecommunication connection 15 is a part of the worldwide public telephone net-work and com-prises a relay station in the form of a g~o~tationary satellite.
The terminal equipment 14 consists of a modem and is pro-vided with an automatic dialling input 16 connected to a second output of the control device 11. Via the telecommu-nication connection 15, the terminal equipment 14 is connect-ed t-o-a c~rresponding terminal-equipment 17 c~nnected to the sampling device 7 and consisting of a modem having ~874g~
auto-reply facilities. Consequently, the monitored machine may belong to a plant which is remotely located (e.g. an oil field), movable (e.g. a ship) and possibly fully automatic (hydroelectric power station). The costs of the components o the inventive system can be kept low as regards the com-ponents assembled locally at the plant including the machine to be monitored. It is reasonable to assume that the plant is connected to the public telephone net-work in such a way that the terminal eq~ipment 17 is operative at regular time intervals while being conrolled by the control device 11 via the terminal equipment 14 in the central monitoring unit 1.
In the preferred embodiment, the terminal equipment 17 is connected to the sampling device 7 via a communication equipment 18 built around a microprocessor provided with a RAM for programs and data and arranged to be charged with programs via a serial port. The sampling device 7 comprises a charge amplifier 1~ and an A/D converter ?O serving to connect the vibration sensor 9 to the communication equipment 18. The latter is arranged to adjust the gain of the charge amplifier 19 via the control input 8 of the sampling means 7, and additionally tocontrol the A/D converter 0. For example, the vibration sensor may be supplemented by several vibra-tion sensors each being connected via an associated charge amplifier to a separate analog input of the A/D converter 20 addressed from the communication equipment 18 while being - controlled by a program stored in its RAM and obtained from a communication equipment ? 1 arranged in the central moni-toring unit 1 and likewise including a microprocessor. This program generates a time series which is stored in the RAM
of the communication equipment 18 and is transmitted after completed sampling to the communication equipment 21 via the telecommunication connection 15. The transmission of the time series may be repeated in case of detected faults, e.g. by using check sums. In addition to programs for sampling, the communication equipment 18 may also receive test programs form the communication equipment 21 for checking the opera-tion of e.g. the charge amplifier 19 and the vibration 1211!~7~4 sensor 9. Before the measuring signal is digitized , it is Eiltered in an antialising filter, i.a. a low pass filter having a steeply declining response characteristic in t~high frequency region. The upper limit frequency can be set from the control monitoring unit 1, depending on the frequency range being currently examined.
In the communication equipment 21 located in the central monitoring unit 1, the microprocessor is provided with programs for further processing of the received time series, i.a. by correcting the measuring values in view of the adjusted gain of the charge amplifier 19, and for conveying the results to the frequency analyzer ~. The latter includes a FFT (Fast Fourier Transform) frequency analyzer 22 having an output connected to a microprocessor 23 provided with a program for processing frequency spectra obtained from a frequency analyzer 22 and forming a table containing levels and frequencies for further processing in the pattern recognition equipment 2.
In the preferred embodiment, the pattern recognition equipment 2 comprises a computer provided with the recog-nition program SIMCA which was originally developed for the processing of chemical spectra of organic substances obtained by means of mass spectroscopes and gas chromato-- graphs ~World, S., et al, Proc. of Symposium on Applied Statistics, Copenhagen, January 22, 1981). In the inventive system, this program has been adjusted for the processing of frequency spectra of machine vibrations. In the course of normal operation of the machine a reference class of frequency spectra is generated and is later compared with each subsequent frequency spectrum. Under normal conditions, it is not necessary to interpret the frequency spectra.
The program calculates for every new frequency spectrum the probability that this spectrum belongs to a class different from the reference class. Should this probability - - -7~
be high, the deviating components in the frequency spectrum can be shown and a diagnosis of the operating condition be made. The result can be presented by means of a printer 24' connected to the pattern recognition equipment 2.
,.
:
Claims (6)
1. In a system adapted for monitoring the condition of a machine by vibration analysis, and wherein the machine has a characteristic frequency spectrum when operating normally, said system including at least one vibration sensor in operative contact with said machine for sensing machine vibrations, and providing a vibration signal at its output, sampling means connected to the output of said vibration sensor, said sampling means including an ampli-fier, a low pass filter postcoupled to said amplifier, and an A/D converter postcoupled to said filter for sampling, amplifying and digitizing the signal obtained from said vibration sensor, separate frequency analysis means arranged to receive the sampled and digitized signal from said sampling means for frequency analysis thereof, and pattern recognition means coupled to said frequency analysis means for detection of any abnormal frequency spectra corresponding to abnormal machine operation, the improvement comprising local data processing means near said machine adapted to store programs for the control thereof, being connected to said vibration sensor, and including a microcomputer inclusive of a random access memory, being arranged for obtaining vibration data from said sensor, and for storing said vibration data in the form of a time series in said memory, said local data processing means also including said sampling means, central monitoring means remote from said local data processing means adapted to store another program therein, and providing for monitoring and further processing of said time series, said central monitoring means including computer means, as well as said frequency analysis means, and said pattern recognition means, said computer means being connected to said frequency analysis means, control means connected to said central monitoring means, and a two-way communication link connecting said local data processing means and said central monitoring means, for periodic transmission of said time series from said memory in said microcomputer of said local data processing means in one direction to said frequency analysis means in said central monitoring means, and for transferring said other program from said central monitoring means back to said local data processing means in a direction opposite to said one direction, said control means providing for control of said amplifier, of said low pass filter, and of said A/D
converter, through said communication link, whereby transmission of said time series from said local data processing means to said central monitoring means can be matched to reception conditions prevailing at said central monitoring means.
converter, through said communication link, whereby transmission of said time series from said local data processing means to said central monitoring means can be matched to reception conditions prevailing at said central monitoring means.
2. A system as defined in claim 1, wherein said communications means includes a telephone line.
3. A system as defined in claim 1, further comprising additional vibration sensors, and respective charge ampli-fiers postcoupled to said vibration sensors, each charge amplifier being connected to said A/D converter.
4. A system as defined in claim 1, wherein said communication means include fault detection means for detecting any error in said time series, and means for repeating transmission of said time series in the event of said error being detected by said detection means.
5. A system as defined in claim 1, wherein said communication means include means adapted to transmit test programs for checking the operation of said data processing means.
6. A system as defined in claim 1, wherein said pattern recognition means includes generating means for generating a reference class of frequency spectra during normal operation of said machine, and for calculating for any new frequency spectrum operatively obtained from said machine the probability that said new frequency spectrum belongs to a class different from any frequency spectrum in said reference class, whereby an abnormal machine condition is detected upon said probability exceeding a predetermined limit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000472768A CA1218744A (en) | 1985-01-24 | 1985-01-24 | System for operational monitoring of a machine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000472768A CA1218744A (en) | 1985-01-24 | 1985-01-24 | System for operational monitoring of a machine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1218744A true CA1218744A (en) | 1987-03-03 |
Family
ID=4129662
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000472768A Expired CA1218744A (en) | 1985-01-24 | 1985-01-24 | System for operational monitoring of a machine |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1218744A (en) |
-
1985
- 1985-01-24 CA CA000472768A patent/CA1218744A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |