Wireless machine monitoring and communication system

• US 5,907,491 A
• Filed: 04/04/1997
• Issued: 05/25/1999
• Est. Priority Date: 08/23/1996
• Status: Expired due to Term

• Current Assignee: Computational Systems Incorporated (Emerson Electric Company)
• Original Assignee: CSI Technology Incorporated (Emerson Electric Company)
• Inventors: Robinson, James C., Czyzewski, Zbigniew, Pearce, James W., Canada, Ronald G.
• Primary Examiner(s): Gordon, Paul P.
• Application Number:
  US08/835,083
• Time in Patent Office: 781 Days
• Field of Search: 364/468.15, 364/468.16, 364/468.17, 364/474.16, 364/551.01, 364/551.02, 364/552, 340/825.06, 340/825.07, 340/825.08, 340/825.22, 340/825.23, 370/77, 370/85.1, 370/85.7, 370/85.8
• US Class Current: 700/108
• CPC Class Codes: G01H 1/003 of rotating machines G01H1/10 takes precedence
• CPC Class Codes: G05B 19/4065 Monitoring tool breakage, life or condition
• CPC Class Codes: G05B 2219/33192 Radio link, wireless
• CPC Class Codes: G05B 2219/37435 Vibration of machine
• CPC Class Codes: G07C 3/00 Registering or indicating the condition or the working of machines or other apparatus, other than vehicles
• CPC Class Codes: H04B 7/2606 Arrangements for base station coverage control, e.g. by using relays in tunnels
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A wireless machine monitoring and communication system includes one or more machine monitors which attach to one or more machines to sense a physical characteristic of the machine, such as vibration or temperature, and to produce wireless transmissions corresponding to the sensed characteristic. A command station executes machine status polling in accordance with a time-division communication protocol and processes machine status data obtained during polling to determine the status of the machine. The machine monitor incorporates a wireless transmitter for transmitting at least status information, and the command station incorporates a wireless receiver for receiving monitor transmissions. To conserve power, the machine monitors are turned on only at preprogrammed times in accordance with the time-division communication protocol. Each machine monitor includes a receiver and the command station includes a transmitter to enable the command station to send commands to each machine monitor. A microcomputer in each monitor analyzes sensor data and a memory stores the analyzed sensor data. Repeaters are employed as necessary to assist in propagating wireless transmissions throughout the system. A tachometer sensor is employed at each machine to provide monitors and sensors with information relating to machine speed. A computer network is connected to the command station for transferring data and for controlling the overall operation of the system.

Claims

1. A communication system for monitoring the status of a machine and communicating the machine'"'"'s status through wireless signals, the system comprising:

a plurality of machine monitors positioned to monitor operational characteristics of a machine, each machine monitor including;

a receiver for receiving wireless signals, including command signals;

at least one sensor for sensing a characteristic of the machine and generating a sensor signal corresponding to the machine characteristic that was sensed;

a data processor for receiving and processing the sensor signals to produce status data and for storing status data;

a transmitter for transmitting wireless status signals corresponding to the status of the machine as represented by status data;

a protocol stored in said data processor;

said data processor for communicating with and controlling said receiver, transmitter, and sensor and for selectively producing power-on and power-off signals for selectively powering said receiver, transmitter, and sensor signal in accordance with said protocol;

an electrical power source and control circuitry responsive to said power-on and power-off signals to selectively power said receiver, transmitter and sensor; and

a command station including a transceiver for transmitting wireless command signals and receiving said wireless status signals.

2. The system of claim 1 wherein said protocol is a time-division communication protocol and said plurality of machine monitors are operable to transmit said wireless status signals in accordance with the time-division communication protocol.

3. The system of claim 2 wherein said command station is operable to transmit wireless command signals which include special request messages, said machine monitors being responsive to said special request messages to perform special functions additional to transmitting said wireless status signals in accordance with the time-division communication protocol.

4. The system of claim 3 wherein said special functions include special data sensing and transmission.

5. The system of claim 3 wherein said special functions include special data analysis.

6. The system of claim 3 wherein said special functions include special data storage.

7. The system of claim 3 wherein said special functions include special data transmission.

8. The system of claim 2 wherein said time-division communication protocol is programmed into a machine monitor before installation.

9. The system of claim 2 wherein said time-division communication protocol is programmed into a machine monitor during installation.

10. The system of claim 9, further comprising an installation control unit for programming the machine monitor during installation.

11. The system of claim 2 wherein said time-division communication protocol is programmed into a machine monitor after installation.

12. The system of claim 11, further comprising an installation control unit for programming the machine monitor after installation.

13. The system of claim 2 wherein each of said plurality of machine monitors includes a timer for selectively energizing and de-energizing the monitor in accordance with said time-division communication protocol.

14. The system of claim 13 wherein said command station includes a timer synchronized with machine monitor timers for controlling the transmission of command signals and the receipt of status signals in accordance with said time-division communication protocol, wherein the machine monitor and command station timers are operable to re-synchronize periodically.

15. The system of claim 1 wherein said protocol is a non-time division communication protocol and said wireless status signals are transmitted by said plurality of machine monitors in accordance with the non-time division communication protocol.

16. The system of claim 1 wherein said at least one sensor includes a vibration sensor for sensing vibrations generated by the machine and producing vibration sensor signals, said data processor being operable to receive the vibration sensor signals and produce frequency domain data corresponding to said vibration sensor signals, compare the frequency domain data to predetermined criteria, and determine an alarm condition when the frequency domain data meets the predetermined criteria.

17. The system of claim 16 wherein said data processor performs a Fourier transform on the sensor signals to produce the frequency domain data in the form of a frequency spectrum.

18. The system of claim 16 wherein said data processor stores at least the frequency domain data.

19. The system of claim 18 wherein stored frequency domain data is transmitted by a monitor in accordance with a non-time-division, asynchronous communication protocol when an alarm condition is present.

20. The system of claim 1 wherein said at least one sensor further includes a tachometer sensor positioned to sense machine revolutions and produce corresponding tachometer signals, said tachometer sensor including a transmitter for transmitting a wireless tachometer signal corresponding to sensed machine revolution information, at least one monitor being operable to receive the wireless tachometer signals.

21. The system of claim 20 wherein one or more of said plurality of machine monitors is operable to selectively energize and de-energize in accordance with machine revolution information contained in said tachometer signals.

22. The system of claim 20 wherein said tachometer signals correspond to whether the machine is on or off.

23. The system of claim 20 wherein said tachometer signals comprise a time series of electrical pulses where each pulse corresponds to the beginning of a machine revolution.

24. The system of claim 1, further comprising one or more repeaters for receiving and re-transmitting said wireless signals for receipt by another repeater, monitor, or the command station.

25. The system of claim 1, further comprising a computer network connected to said command station for transferring data and controlling wireless communication within the system.

26. The system of claim 1 wherein said transmitter includes a spread spectrum transmitter and said receiver includes a spread spectrum receiver, each said transmitter and receiver using spread spectrum communication techniques to avoid interference from other radio frequency emitters, said spread spectrum techniques including the use of a first PN code for communicating according to a first spectrum spreading sequence.

27. The system of claim 26, further comprising an installation control unit for configuring a machine monitor, said installation control unit comprising:

a wireless installation control unit transmitter and receiver using spread spectrum communication techniques including the use of a second PN code that is different than said first PN code;

an installation control unit data processor for controlling and causing the installation control unit transmitter to transmit configuration signals to said monitor for reprogramming of the monitor data processor and for processing wireless signals transmitted by the monitor; and

a user interface for inputting user commands to the installation control unit data processor to control reprogramming of machine monitors.

28. A wireless machine monitoring system comprising:

a plurality of machine monitors, each monitor having at least;

a) one sensor for sensing a parameter of the machine and producing digital data corresponding thereto;

b) a wireless monitor transmitter and receiver; and

c) a monitor data processor for controlling the operation of the sensor, transmitter and receiver, for receiving and processing the digital data according to a first processing configuration, for communicating the digital data to the transmitter and causing the transmitter to produce transmission signals corresponding to the digital data;

a command station having at least;

a) a command station receiver and associated circuitry for producing received digital data; and

b) a command station data processor for controlling and causing the receiver and associated circuitry to receive a transmission signal and produce received digital data corresponding to the transmission signal, said command station data processor being operable to store said received digital data; and

means for reprogramming the monitor data processor to change the programmed processing configuration to reconfigure the machine monitor to process the data according to a second processing configuration.

29. The system of claim 28 wherein said means for reprogramming includes a hand-held configuration device comprising:

a wireless configuration device transmitter and receiver;

a configuration device data processor for controlling and causing the transmitter to transmit configuration signals to said monitor for reprogramming of the monitor data processor and for processing wireless signals transmitted by the monitor; and

a user interface for inputting user commands to the configuration device data processor to control reprogramming of machine monitors.

30. The system of claim 29 wherein the transmitters and receivers of said plurality of machine monitors and said configuration device utilize spread spectrum communication techniques including the use of PN code sequencing to define a spectrum spreading sequence.

31. The system of claim 30 wherein the PN code used for communication between a monitor and the command station is different than the PN code used for communication between a monitor and the configuration device.

32. The system of claim 28 wherein said means for reprogramming is disposed in said command station.

33. A method of determining and communicating the status of a machine, the method comprising the steps of:

programming a plurality of machine monitors in accordance with a communication protocol;

transmitting wireless command signals from a command station to said plurality of machine monitors in accordance with the communication protocol, said command station and machine monitors comprising a machine monitoring and communication system;

sensing a characteristic of the machine being monitored in accordance with said command signals to produce sensor signals;

processing the sensor signals to produce machine status data; and

transmitting wireless status signals representing status data to the command station in accordance with the time-division communication protocol.

34. The method of claim 33, further comprising the step of transmitting special request messages from the command station to a machine monitor to command the machine monitor to perform special functions additional to those provided in accordance with the communication protocol.

35. The method of claim 34 wherein said special functions include special data sensing and transmission.

36. The method of claim 34 wherein said special functions include special data analysis.

37. The method of claim 34 wherein said special functions include special data storage.

38. The method of claim 34 wherein said special functions include special data transmission.

39. The method of claim 33 wherein said communication protocol is a time-division communication protocol.

40. The method of claim 33 wherein said communication protocol is a non-time division communication protocol.

41. The method of claim 33 wherein a machine monitor is programmed with the communication protocol before installation.

42. The method of claim 33 wherein a machine monitor is programmed with the communication protocol during installation.

43. The method of claim 33 wherein a machine monitor is programmed with the communication protocol after installation.

44. The method of claim 33, further comprising the step of propagating wireless command and status signals with a repeater positioned intermediate a monitor and the command station.

45. The method of claim 33 wherein said processing step includes the steps of:

producing frequency domain data from said sensor signals;

comparing the frequency domain data to predetermined criteria; and

determining an alarm condition that is transmitted with the status signals when the frequency domain data meets the predetermined criteria.

46. The method of claim 45, further comprising the steps of:

storing frequency domain data over time; and

transmitting stored frequency domain data in accordance with a non-time-division, asynchronous communication protocol when an alarm condition is present.

47. The method of claim 46, further comprising the step of analyzing frequency domain data to determine the cause of the alarm condition.

48. The method of claim 33 wherein each of said plurality of machine monitors power up to receive wireless command signals, sense machine characteristics, and transmit wireless status signals only during designated periods of time as defined by a time-division communication protocol, wherein each designated period of time comprises a time slice within the time-division communication protocol.

49. The method of claim 48, further comprising the step of modifying the time-division communication protocol to accommodate changes to the communication system.

50. The method of claim 49 wherein said modifying step includes adding one or more time slices.

51. The method of claim 49 wherein said modifying step includes deleting one or more time slices.

52. The method of claim 49 wherein said modifying step includes rearranging existing time slices.

53. The method of claim 33 wherein said characteristic being sensed is vibration.

54. The method of claim 33 wherein said characteristic being sensed is speed.

55. A method of periodically polling a plurality of machine monitors for machine status data in accordance with an established communication protocol, said method comprising the steps of:

defining a time-division schedule of events to occur during a periodic polling sequence, said events including;

transmitting wireless command signals from a command station to other communication devices including machine monitors;

receiving wireless command signals by said machine monitors;

sensing one or more characteristics of the machine to produce sensor signals;

processing said sensor signals to produce machine status signals; and

transmitting wireless status signals to the command station;

assigning each communication device a time slice within the time-division schedule during which the device powers up to receive and execute commands communicated by the command signals; and

polling machine monitors in accordance with said time-division schedule to determine the status of the machine.

56. The method of claim 55, further comprising the steps of determining when a particular machine monitor does not communicate with the command station in accordance with the time-division schedule, and executing a communication procedure for re-establishing communication with the particular machine monitor.

57. The method of claim 56 wherein said executing step includes the step of periodically powering up the particular machine monitor for increasingly longer time periods to listen for polling commands.

58. The method of claim 56 wherein said executing step includes:

continuing to periodically poll machine monitors in accordance with the time-division schedule during a first predetermined time period;

if communication with the particular machine monitor is not re-established within the first predetermined time period, selecting one or more repeaters to relay a command requesting the particular machine monitor to perform a transmission strength scan at a first designated time;

listening during a second predetermined time period for signals transmitted by the particular machine monitor during the commanded transmission strength scan;

processing transmission strength scan signals received by the selected repeaters to determine a most favorable repeater and transmission strength scan;

commanding the particular machine monitor to perform a transmission scan at the most favorable transmission strength at a second designated time that is later than the first designated time;

acknowledging proper receipt of the particular machine monitor'"'"'s transmission scan by assigning the particular machine monitor a temporary time slice within the time-division schedule; and

reconfiguring the time-division schedule to assign the particular machine monitor a permanent time slice once synchronization with the most favorable repeater is established.