Distributed logic control system and method

• US 4,858,102 A
• Filed: 04/14/1987
• Issued: 08/15/1989
• Est. Priority Date: 07/19/1985
• Status: Expired due to Fees

• Current Assignee: El Paso Technologies Company A Partnership of TX
• Original Assignee: El-Mul Technologies Ltd. (PHOTONIS Technologies SAS)
• Inventors: Lovrenich, Rodger T.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US07/038,018
• Time in Patent Office: 854 Days
• Field of Search: 307/149, 364/167, 364/188, 364/474, 364/170, 364/136, 364/176, 364/475, 364/478, 364/141, 364/183, 364/184, 364/148, 364/152, 364/147, 364/140
• US Class Current: 700/7
• CPC Class Codes: G05B 19/058 Safety, monitoring
• CPC Class Codes: G05B 2219/1159 Image table, memory
• CPC Class Codes: G05B 2219/1204 Multiprocessing, several plc's, distributed logic control
• CPC Class Codes: G05B 2219/13066 Execute next step if state, control zone changes
• CPC Class Codes: G05B 2219/13067 Use of variables, symbols in instructions, to indicate mechanisms, interfaces
• CPC Class Codes: G05B 2219/13189 On error, look in table for alternative allowed next instruction
• CPC Class Codes: G05B 2219/14044 Operating time test for over or under conditions
• CPC Class Codes: G05B 2219/14055 Make log, journal, history file of state changes
• CPC Class Codes: G05B 2219/14074 Signature analysis, recorded states, zones are compared to actual
• CPC Class Codes: G05B 2219/14091 Message generation, composer from variables and states, zones
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A system and method for controlling operation of a plurality of elements in an automated process, such as a production process, and indicating error conditions as they occur. Each unique set of input and output conditions of the various system elements defines a unique logic state or zone. Thus, there are defined a multiplicity of valid system logic states or zones, each having a unique input/output image. A predetermined sequence of zones, productive zones representing designed machine operations, is stored in a zone table. All zones not explicitly defined in the zone table are automatically treated as error zones. A zone engine automatically cycles to observe any change in input/output image. Any change in inputs from the various system elements automatically transfer action to the unique zone associated with such inputs, resulting in corresponding changes in control outputs to the system elements and/or display an error message as appropriate.

Claims

1. A machine control system which comprises, in combination, a machine including means for producing motion at said machine and means for sensing machine conditions, and control means responsive to a predefined input from said condition-sensing means for providing a predefined output to said motion-producing means, characterized in that said control means comprises:

means for tabulating said predefined input and output in a combination representative of a preselected set of operation of said machine, each said combination representing an input/output image indicative of a corresponding zone in said preselected set, and said corresponding zone having associated therewith an allowed next zone with at least one of said corresponding zones having associated therewith a plurality of allowed next zones;

means for monitoring said predefined input and output responsive to a change in said predefined input and output to formulate a new input/output image;

means for comparing said new input/output image to an input/output image in said tabulating means indicative of said allowed next zone; and

means for indicating an error condition in the event that said new input/output image does not match that of said next zone in said preselected set.

2. The system set forth in claim 1 wherein said tabulating means includes means for establishing a maximum operating time in a zone of said predetermined set;

wherein said comparing means includes means for measuring time of operation within a zone in said preselected set and means for comparing said time of operation to said maximum operating time; and

wherein said error-condition indicating means includes means for indicating said error condition in response to a change in said predefined input and output when said time of operation in said zone is outside of said maximum operating time.

3. The system set forth in claim 1 wherein said error-condition indicating means includes means for providing an error signal indicative of an input and output condition at said machine upon detection of an error condition, and means responsive to said error signal for formulating and displaying an error message indicative of said error condition.

4. The system set forth in claim 3 wherein message-formulating means includes a table of predefined error message segments corresponding to an error condition at said machine, and means responsive to said error signal for gathering error message segments from said table as a function of said error signal and thereby formulating said error message.

5. The system set forth in claim 4 wherein said message-formulating means comprises a visual display.

6. The system set forth in claim 3 wherein said control means further comprises memory means for storing an input/output image data for operating zones of said machine;

and

wherein said error-condition indicating means comprises means for retrieving data from said memory means indicative of an operating zone, and means for formulating said error message as a function of said input/output image data.

7. A machine control system which comprises, in combination, a machine including motion-producing means for producing motion at said machine and condition-sensing means for sensing machine conditions, and control means responsive to a predefined input from said condition-sensing means for providing a predefined output to said motion-producing means, characterized in that said control means comprises:

means for tabulating said predefined input and output in a combination representative of a preselected set of operations of said machine, each said combination representing an input/output image indicative of a corresponding zone in said preselected set;

means for monitoring said predefined input and output responsive to a change in said predefined input and output to formulate a new input/output image;

means for comparing said new input/output image to an input/output image in said tabulating means wherein said means for comparing indicates a next zone in said preselected set;

means for indicating an error condition in the event that said new input/output image does not match that of a next zone in said preselected set; and

means for initiating operation of said machine at each corresponding zone of said preselected set, illumination means associated with each said initiating means, and energizing means for energizing said illumination means at a state of a plurality of illumination states to indicate one of a plurality of available operating modes at said machine.

8. The system set forth in claim 7 wherein said initiating means and said illumination means comprises an illuminated pushbutton associated with a preselected operating zone of said control means and a corresponding action at said machine, and wherein said energizing means comprises means for illuminating said illuminated pushbutton in one of said plurality of illumination states as a function of availability of operation of said corresponding action at said machine.

9. The system set forth in claim 8 wherein said energizing means comprises means for flashing said illuminated pushbutton at a first rate to indicate availability of said corresponding action associated with said pushbutton, means for flashing said illuminated pushbutton at a second rate different from said first rate when said corresponding action is in operation, means for steadily illuminating said pushbutton when said corresponding action is completed, and means for extinguishing said illuminated pushbutton when said corresponding action is not available for implementation.

10. A method of operating a machine capable of performing a plurality of physical operations in a preselected sequence wherein said machine is controlled through input and output devices, said method comprising the steps of:

establishing a set of machine operations defined by a set of operating zones, each zone of said operating zones having a corresponding input/output image of inputs and outputs from said input and output devices and each zone having a corresponding allowed next zone with at least one of said operating zones having a plurality of allowed next zones;

monitoring inputs and outputs from said input and output devices during a step in said plurality of physical operations and comparing said inputs and outputs to said corresponding input/output image associated with said step;

advancing machine operation to a next step in said set of machine operations when a change in said inputs and outputs produces a zone image corresponding to said allowed next zone; and

indicating an error condition when a change in said inputs and outputs produces a zone image other than that corresponding to said allowed next zone.

11. The method set forth in claim 10 comprising the additional steps of:

monitoring a time of operation in each zone of said operating zones;

comparing said time of operation in a particular zone to a predetermined maximum time associated with said particular zone; and

indicating said error condition when said time of operation is greater than said predetermined maximum time.

12. The method set forth in claim 11 comprising the additional steps of:

storing a plurality of predetermined message segments in plain text corresponding to actions to be taken in said operating zones and input and output conditions at said machine;

establishing an error signal in response to an indication of said error condition, said error signal including segments reflecting input and output conditions at said machine in predetermined sequence upon detection of said error condition;

composing an error message as a sequence of said predetermined message segments corresponding to and in the order of said error signal segments; and

displaying said error message.

13. A method of controlling a machine mechanism for obtaining a single non-interfering machine motion through an operating sequence, said method comprising the steps of:

(a) coupling input/output means to said machine mechanism for providing input/output signals which vary as a function of motion of said machine mechanism through said sequence;

(b) establishing a plurality of distinct mechanism operating zones each characterized by a combination of said input/output signals and each having associated therewith an allowed next operating zone, said operating zone including at lest two zones corresponding respectively to one or more operating states of said machine mechanism and an error zone, and at least one of said operating zones is associated with a plurality of next operating zones;

(c) monitoring said input/output signals in each of said plurality of distinct mechanism operating zones for the combination of said input/output signals corresponding to said allowed next operating zone;

(d) advancing machine operation to said allowed next operating zone upon detection of a corresponding input/output signal combination; and

(e) advancing machine operation to said error zone and indicating an error condition upon detection of a combination of an input/output signal other than an input/output signal corresponding to a subsequent mechanism operating zone.

14. The method set forth in claim 13 for controlling a machine system which includes at least two of said machine mechanisms, said steps (a)-(c) being carried out independently for each said machine mechanism, said method comprising the additional steps of:

(f) identifying operating zones for said at least two machine mechanisms in which operation of said at least two machine mechanisms interfere with each other; and

(g) inhibiting advancement of operation in said step (d) for a selected one of said machine mechanisms when an operating zone of another of said machine mechanisms is one identified in said step (f) such that advancement could cause interference between said at least two machine mechanisms.

15. The method set forth in claim 13 for controlling a machine system which includes at least two of said mechanisms for performing operations in a predetermined sequence in which operation of a first of said mechanisms is a prerequisite to operation of a second of said mechanisms, said steps (a)-(c) being carried out independently for each of said mechanisms, said method comprising the additional steps of:

(f) storing information indicative of operation of said first mechanism, and

(g) inhibiting advancement of operation in said step (d) for said second mechanism in the absence of information stored in said step (f) indicative of operation of said first mechanism.

16. A machine control system which includes a plurality of machine mechanisms for performing operations in a sequence and means for controlling operation of said mechanisms comprising:

input/output means couples to each of said plurality of machine mechanisms for providing input/output signals in combinations indicative of a plurality of stages of operation associated with said plurality of machine mechanisms; and

control means coupled to each of said plurality of machine mechanisms, said control means including means for receiving input/output signals from an associated input/output means, said control means having stored therein a table of predefined operating zones for each of said plurality of machine mechanisms as a function of differing combinations of an associated input/output signal and having associated therewith an allowed next operating zone wherein a least one of said operating zones has associated therewith a plurality of next operating zones, said control means having further stored therein tables of predefined zones in which operation of said plurality of machine mechanisms could interfere with each other, and means for driving each of said plurality of machine mechanisms as a combined function of said associated input/output signal and an indicia stored in said tables.

17. The system set forth in claim 16 for performing operations on a workpiece in said predetermined sequence, an operation performed by a first of said mechanisms being a prerequisite to performance of an operation by a second of said mechanisms in said sequence, said control means further including means having stored therein an indicia indicative of operations performed on a workpiece in said system, and means for inhibiting operation of said second mechanism of said workpiece when said indicia indicates a lack of operation of said first mechanism on said workpiece.

18. A machine control system which comprises, in combination, a machine including means for producing motion at said machine and means for sensing machine conditions, and control means responsive to predefined inputs from said condition-sensing means for providing predefined outputs to said motion-producing means, characterized in that said control means further comprises

means for manually initiating operation of said machine at each of a plurality of differing zones in a preselected set of operations at said machine, illumination means associated with each said manually-initiating means, and means for energizing said illumination means at differing illumination states to indicate differing available operating modes at said machine.

19. The system set forth in claim 18 wherein said manually-initiating means and said illumination means comprises illuminated pushbuttons each associated with a preselected operating zone of said control means and a corresponding action at said machine, and wherein said energizing means comprises means for illuminating each said illuminated pushbutton in differing illumination modes as a function of availability of operation of the corresponding action at said machine.

20. The system set forth in claim 19 wherein said energizing means comprises means for flashing each said illuminated pushbutton at a first rate to indicate availability of action associated with the said pushbutton, means for flashing each said illuminated pushbutton at a second rate different from said first rate when the associated said action is in operation, means for steadily illuminating each said pushbutton when the associated said action is completed, and means for extinguishing each said illuminated pushbutton when the associated said action is not available for implementation.

21. An apparatus for controlling a machine comprising:

memory means for storing at least two input/output images, each input/output image having associated therewith a present zone and an allowed next zone with at least one input/output image having associated therewith a plurality of allowed next zones;

monitoring means for receiving an input requiring a change in a present input/output image to a new input/output image;

means for comparing an input/output image of said allowed next zone with said new input/output image;

means for executing said input and for replacing said present input/output image with said input/output image of said allowed next zone if said new input/output image matches said allowed next none; and

means for indicating an error condition when said new input/output image does not match said input/output image of said allowed next zone.

22. The apparatus of claim 21 further comprising timing means for measuring a duration of time in said present zone wherein said apparatus moves to a specified allowed next zone when said duration exceeds a predetermined duration for said present zone.

23. The apparatus of claim 21 further comprising interference inhibit means for inhibiting said execution means when execution could interfere with a current zone of a second apparatus.

24. The apparatus of claim 21 further comprising part process means for inhibiting said execution means when a part process record of a workpiece to be worked on by said apparatus indicates said workpiece is not prepared for an operation to be performed.

25. The apparatus of claim 21 wherein said error means comprises:

a first table containing an identification of said apparatus;

a second table containing a zone name of said present zone;

a third table containing an input/output name of said input/output image;

a fourth table containing a current status of said present zone; and

a fifth table containing a plurality of error designations wherein said error indicating means formulates an error message indicative of said error condition.

26. A method for controlling a machine having a present zone, an input/output image of said present zone, and at least two allowed next zones, wherein said method comprises the steps of:

receiving an input representative of a new input/output image of said machine;

comparing an input/output image of a first allowed next zone of said at least two allowed next zones with said new input/output image;

changing said present zone to said first allowed next zone if said input/output image of said first allowed next zone matches said new input/output image; and

comparing an input/output image of a second allowed next zone of said at least two allowed next zones with said new input/output image if said new input/output image did not match said input/output image of said first allowed next zone.

27. A method for controlling a machine having a present zone, an input/output image of said present zone, and a plurality of allowed next zones, wherein said method comprises the steps of:

(a) receiving an input representative of a new input/output image of said machine;

(b) comparing an input/output image of a particular allowed next zone of said plurality of allowed next zones with said new input/output image;

(c) changing said present zone of said machine to said particular allowed next zone if said input/output image of said particular allowed next zone matches said new input/output image; and

(d) repeating steps (b) and (c) if said input/output image of said particular allowed next zone does not match said new input/output image until all of said plurality of allowed next zones have been compared to said new input/output image.