Batch process control using expert systems

• US 5,058,043 A
• Filed: 04/05/1989
• Issued: 10/15/1991
• Est. Priority Date: 04/05/1989
• Status: Expired due to Term

• Current Assignee: Pavilion Technologies Incorporated (Rockwell Automation, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Skeirik, Richard D.
• Primary Examiner(s): Black, Thomas G.
• Application Number:
  US07/333,536
• Time in Patent Office: 923 Days
• Field of Search: 364/500, 364/550, 364/551.01, 364/513, 364/300
• US Class Current: 700/167
• CPC Class Codes: B01J 19/004 Multifunctional apparatus for automatic manufacturing of various chemical products sequential reactions B01J19/0046
• CPC Class Codes: G05B 13/028 using expert systems only
• CPC Class Codes: G06F 9/44 Arrangements for executing specific programs
• CPC Class Codes: Y10S 706/906 Process plant

Abstract

Batch process control is improved by defining a step endpoint condition in an expert system knowledge base; using the expert system to monitor for the occurrence of the endpoint in the batch process; and triggering a change in a batch process condition when the endpoint is found. Preferably, the expert system and the batch process condition change are implemented as modules which execute under control of timing and sequencing functions in a supervisory control system, and the change affects a setpoint (or other control objective) in a continuous control system. Multiple instances of modular expert systems allow parallel process units to be easily controlled.

Claims

1. An expert system based batch process control method, comprising the steps of:

(a) initiating the batch process;

(b) monitoring, using knowledge in the expert system which defines an endpoint condition in the batch process, for said endpoint condition; and

(c) changing, using the expert system, a control objective of the batch process when the expert system detects said endpoint condition.

2. The expert system based batch process control method of claim 1, wherein step (a) comprises the step of:

initiating said batch process in accordance with a command from a process operator.

3. The expert system based batch process control method of claim 2, wherein said initiating step further comprises:

using a toggle on/off function of an event module in a modular supervisory control system.

4. The expert system based batch process control method of claim 1, wherein step (a) comprises the step of:

initiating said batch process automatically when a previous step in said batch process reaches its endpoint.

5. The expert system based batch process control method of claim 4, wherein said initiating step further comprises the step of:

causing an event module in a modular supervisory control system to execute.

6. The expert system based batch process control method of claim 1, wherein step (b) comprises the step of:

cycling said expert system.

7. The expert system based batch process control method of claim 1, wherein step (b) further comprises the steps of:

(i) executing said expert system;

(ii) waiting an idle time; and

(iii) executing said expert system after said idle time.

8. The expert system based batch process control method of claim 1, wherein step (b) further comprises the step of:

(i) using an inference engine with said knowledge to detect said endpoint condition.

9. The expert system based batch process control method of claim 8, wherein step (i) further comprises the step of:

using said knowledge in the form of decision-making knowledge about the domain.

10. The expert system based batch process control method of claim 8, wherein step (i) further comprises the step of:

using said knowledge in the form of a group of rules around classes of objects.

11. The expert system based batch process control method of claim 8, wherein step (i) further comprises the step of:

using said knowledge in the form of rules structured according to a limited set of predetermined types.

12. The expert system based batch process control method of claim 8, wherein step (i) further comprises the step of:

using said knowledge in the form of at least one rule for representing knowledge about the domain.

13. The expert system based batch process control method of claim 1, wherein step (c) further comprises the step of:

changing said control objective using changes encoded directly in said knowledge.

14. The expert system based batch process control method of claim 1, wherein step (c) further comprises:

changing said control objective using a batch-type control system triggered by said expert system.

15. The expert system based batch process control method of claim 1, wherein step (c) further comprises the step of:

changing said control objectives using a process operator in accordance with communication from said expert system.

16. The expert system based batch process control method of claim 1, wherein step (b) further comprises the step of:

using said knowledge in an expert system module in a modular supervisory control system.

17. The expert system based batch process control method of claim 1, wherein step (b) further comprises the step of:

using timing and sequencing functions to repeatedly execute an expert system module in a modular supervisory control system.

18. The expert system based batch process control method of claim 1, wherein step (c) further comprises the step of:

using an explicit request in said knowledge to execute an event module in a modular supervisory control system.

19. A batch process control system, comprising:

(a) control means for controlling process conditions of the batch process, so as to maintain said process conditions at pre-defined objectives; and

(b) expert system means, responsive to said control means, for causing said control means to change said pre-defined objectives when an endpoint condition, defined by knowledge in said expert system means, is detected by said expert system means.

20. The batch process control system of claim 19, wherein said control means comprises:

a distributed control system.

21. The batch process control system of claim 20, wherein said expert system means is part of said distributed control system.

22. The batch process control system of claim 19, wherein said control means comprises:

a programmable logic controller.

23. The batch process control system of claim 19, wherein said control means comprises:

a single loop controller.

24. The batch process control system of claim 19, wherein said control means comprises:

a distributed control system, and

a supervisory controller supervising said distributed control system.

25. The batch process control system of claim 24, wherein said expert system means is part of said supervisory controller.

26. The batch process control system of claim 24, wherein said supervisory controller comprises:

an expert system module, and

feedback control module.

27. The batch process control system of claim 24, wherein said supervisory controller comprises:

an event module.

28. The batch process control system of claim 19, wherein said expert system means comprises:

a knowledge base, and

an inference engine responsive to said knowledge base.

29. The batch process control system of claim 28, wherein said knowledge base comprises:

decision-making knowledge about the domain.

30. The batch process control system of claim 28, wherein said knowledge base comprises:

a group of rules around classes of objects.

31. The batch process control system of claim 28, wherein said knowledge base comprises:

at least one rule for representing knowledge about the domain.

32. The batch process control system of claim 28, wherein said knowledge base comprises:

rules structured according to a limited set of predetermined types.

33. The batch process control system of claim 28, further comprising:

interface means for providing input data used in said knowledge base.

34. The batch process control system of claim 33, wherein said interface means receives said input data from a process measurement database.

35. The batch process control system of claim 33, wherein said interface means receives said input data from a process control system.

36. The batch process control system of claim 33, wherein said interface means comprises:

means for sending a request for a change to said control means.

37. The batch process control system of claim 33, wherein said interface means comprises:

terminal means having query and text display function.

38. The batch process control system of claim 19, wherein said expert system means comprises:

an expert system module residing in a supervisory controller.

39. The batch process control system of claim 19, wherein said expert system means comprises:

an expert system module in a modular supervisory process control system.

40. The batch process control system of claim 39, wherein said modular supervisory process control system further comprises:

template based rule editor means for configuring said expert system module.

41. The batch process control system of claim 40, wherein said template rule editor uses three pre-defined rule structures entered through forms.

42. The batch process control system of claim 19, wherein said expert system means is part of said control means.

43. A batch process control system, comprising:

(a) control means for controlling at least one process condition of the batch process, in accordance with a desired objective; and

(b) expert system means, responsive to said control means, for causing said control means to change said desired objective when an endpoint condition, defined by knowledge in said expert system means, is detected by said expert system means.

44. The batch process control system of claim 43, wherein said control means comprises:

a distributed control system.

45. The batch process control system of claim 44, wherein said expert system means is part of said distributed control system.

46. The batch process control system of claim 43, wherein said control means comprises:

a programmable logic controller.

47. The batch process control system of claim 43, wherein said control means comprises:

a single loop controller.

48. The batch process control system of claim 43, wherein said control means comprises:

a distributed control system, and

a supervisory controller supervising said distributed control system.

49. The batch process control system of claim 48, wherein said expert system means is part of said supervisory controller.

50. The batch process control system of claim 48, wherein said supervisory controller comprises:

an expert system module, and

feedback control module.

51. The batch process control system of claim 48, wherein said supervisory controller comprises:

an event module.

52. The batch process control system of claim 43, wherein said expert system means comprises:

a knowledge base, and

an inference engine responsive to said knowledge base.

53. The batch process control system of claim 52, wherein said knowledge base comprises:

decision-making knowledge about the domain.

54. The batch process control system of claim 52, wherein said knowledge base comprises:

a group of rules around classes of objects.

55. The batch process control system of claim 52, wherein said knowledge base comprises:

at least one rule for representing knowledge about the domain.

56. The batch process control system of claim 52, wherein said knowledge base comprises:

rules structured according to a limited set of predetermined types.

57. The batch process control system of claim 52, further comprising:

interface means for providing input data used in said knowledge base.

58. The batch process control system of claim 57, wherein said interface means receives said input data from a process measurement database.

59. The batch process control system of claim 57, wherein said interface means receives said input data from a process control system.

60. The batch process control system of claim 57, wherein said interface means comprises:

means for sending a request for a change to said control means.

61. The batch process control system of claim 57, wherein said interface means comprises:

terminal means having query and text display function.

62. The batch process control system of claim 43, wherein said expert system means comprises:

an expert system module residing in a supervisory controller.

63. The batch process control system of claim 43, wherein said expert system means comprises:

an expert system module in a modular supervisory process control system.

64. The batch process control system of claim 63, wherein said modular supervisory process control system further comprises:

template based rule editor means for configuring said expert system module.

65. The batch process control system of claim 64, wherein said template based rule editor uses three pre-defined rule structures entered through forms.

66. The batch process control system of claim 43, wherein said expert system means is part of said control means.

67. A batch process control system, comprising:

(a) first event module means for changing a first condition of the batch process;

(b) expert system module means having a plurality of rules defining an endpoint condition of the batch process and responsive to data from the batch process for detecting said endpoint condition; and

(c) second event module means, responsive to said expert system means, for changing a second condition of the batch process, upon detection of said endpoint condition by said expert system means.

68. The process control system of claim 67, wherein said first condition of said first event module means comprises:

a desired process control objective.

69. The process control system of claim 67, wherein said first condition of said first event module means comprises:

a parameter used to control the batch process.

70. The batch process control system of claim 67, wherein said expert system means comprises:

means for running said expert system means until said endpoint condition is detected.

71. The batch process control system of claim 67, wherein said first event module changes said first condition of a distributed control system.

72. The batch process control system of claim 67, wherein said first event module changes said first condition of a programmable logic controller.

73. The batch process control system of claim 67, wherein said first event module changes said first condition of a single loop controller.

74. The batch process control system of claim 67, further comprising:

a statistical test module.

75. The batch process control system of claim 67, further comprising:

a feedback control module.

76. The batch process control system of claim 67, further comprising:

a feedforward control module.

77. The batch process control system of claim 67, wherein first event module means, said expert system module means, and said second event module means are part of a real-time control program.

78. The batch process control system of claim 77, wherein said real-time control program further comprises:

modular timing and sequencing functions.

79. The batch process control system of claim 78, wherein said modular timing and sequencing functions control execution of said first event module means, said expert system module means, and said second event module means in accordance with module timing functions and parameters and/or in accordance requests for module execution.

80. The batch process control system of claim 67, wherein said first event module means is a batch supervisory module.

81. The batch process control system of claim 67, wherein said second event module means is a batch supervisory module.

82. The batch process control system of claim 67, wherein said first event module means comprises:

event change module means for changing an analog target value.

83. The batch process control system of claim 67, wherein said first event module means comprises:

event change module means for changing an digital target value.

84. The batch process control system of claim 67, wherein said second event module means comprises:

event change module means for changing an analog target value.

85. The batch process control system of claim 67, wherein said second event module means comprises:

event change module means for changing a digital target value.

86. The batch process control system of claim 67, wherein said first event module means comprises:

event change module means for changing a target value to a pre-defined absolute value.

87. The batch process control system of claim 67, wherein said first event module means comprises:

event change module means for changing a target value by a fixed amount.

88. The batch process control system of claim 67, wherein said first event module means comprises:

event change module means for changing at least two target values.

89. The batch process control system of claim 67, wherein said second event module means comprises:

event change module means for changing a target value to a pre-defined absolute value.

90. The batch process control system of claim 67, wherein said second event module means comprises:

event change module means for changing a target value by a fixed amount.

91. The batch process control system of claim 67, wherein said second event module means comprises:

event change module means for changing at least two target values.

92. The batch process control system of claim 67, further comprising feedback control module means for changing a recipe of the batch process, said recipe being in said first event module means.

93. The batch process control system of claim 92, further comprising means for changing a value of said recipe.

94. The batch process control system of claim 92, further comprising means for changing a time duration of said recipe.

95. The batch process control system of claim 67, further comprising feedback control module means for changing a recipe of the batch process, said recipe being in said second event module means.

96. The batch process control system of claim 95, further comprising means for changing a value of said recipe.

97. The batch process control system of claim 95, further comprising means for changing a time duration of said recipe.

98. The batch process control system of claim 67, further comprising real-time control program means for controling, in accordance with module timing and/or sequencing functions, the execution of said first event module means, said expert system module means, and/or said second event module means.

99. The batch process control system of claim 67, further comprising build-supervisor means for specifying using a template entry said first event module means, said expert system module means, and/or said second event module means.

100. A batch process control system, comprising:

(a) first event module means for changing a first condition of the batch process;

(b) second event module means for changing a second condition of the batch process;

(c) following domino timing function means for causing said second module means to execute when said first event module means turns off, for keeping said second event module means turned on for a specified execution time interval, and for turning said second event module means off after said specified execution time interval.

101. A batch process control system, comprising:

(a) first event module means for changing a first condition of the batch process;

(b) second event module means for changing a second condition of the batch process; and

(c) first domino timing function means for causing said first event module means to execute when said first event module is turned on, for keeping said first event module means turned on for a specified execution time interval, and for turning said first event module means off after said specified execution time interval.