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Unformatted text preview: ary areas
Controller 1 Controller 2 Process 1 Process 2 Overlap areas (side effects of decisions and control actions)
Controller 1 Controller 2 Process ¾ Î » º ¹ É ¸ · µ ¿ ¶ µ ´ c Î » º ¹ É ¸ · µ ¿ ¶ µ ´ c Sensors Measured variables Process inputs Human Supervisor (Controller)
Model of Process Model of Automation Automated Controller
Controls Displays Model of Process Model of Interfaces Controlled Process Disturbances Process outputs Actuators
Controlled variables Process models must contain: Required relationship among process variables Current state (values of process variables) The ways the process can change state
Î Î » º ¹ ¸ · µ ¶ µ ´ c Relationship between Safety and Process Model
Accidents occur when the models do not match the process and incorrect control commands are given (or correct ones not given) How do they become inconsistent? Wrong from beginning e.g. uncontrolled disturbances unhandled process states inadvertently c...
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- Spring '09