1. Production Scheduling: location of the user in the decision-making architecture Peter G. Higgins

2. Outline Standard scheduling software –features –design criteria Real scheduling environment Decision Architecture Cognitive Work Analysis

3. Heuristic produces sequence

4. Standard Decision Architecture Scheduling Rules GANTT CHART Timing at resources Performance prediction

5. Normative Design Criteria Operations Research Model –few attributes due date processing time Goals –maximise resource utilisation –minimise tardiness Heuristics –tendency to meet goals for simple problems all jobs available single resource

6. Real Scheduling Complex –especially job shops Uncertainties –job arrivals, material availability, processing & set-up times Perplexity –multiple goals conflict importance varies

7. Standard Solution for Mismatch between Design Model and Reality Human moves jobs using mouse

8. human activity centrally Locate human activity centrally in the decision- making process –computer: data representation, heuristics, rules Cognitive Work AnalysisUse Cognitive Work Analysis to analyse the work domain and decision-making activities in complex systems in which there are many competing and conflicting goals. significationUse theories of signification to inform interface design. Decision Architecture for Real Environments

9. GANTT CHART Timing at resources Performance prediction JOBS WINDOWS Machine n Sequence Job attributes Machine 1 Sequence Job attributes Unassigned Sequence Job attributes Scheduling Rules Knowledge-Based Adviser HUMAN DECISION MAKING Context Setting Pattern Recognition Decision Architecture

10. Tardiness Weighted Tardiness Net Weighted Tardiness Resource’s Weighted Tardiness

11. Time constraint on Due date

12. Earliest Due Date Due Date

14. Detailed data in pop-up Visible on double clicking Visible on double clicking

15. Complexity and Perplexity of the Real Domain Apply Cognitive Work Analysis

16. Ends Means PhysicalDevice PhysicalFunction

18. Goal: Low press set-up time Scan available jobs Identify set of jobs requiring current requiring current major set-up Activity Analysis #1

19. Many feasible goals Low press set-up time Particular jobs meet their due date their due date Activity Analysis

20. Low press idle time Low press set-up time Fully utilise all machines Maximise productivity Maximise short-term financial viability Goal Structure

22. Human normally operates with these goals Visualisation of measures of performance of performance Goal structure used to design DSS Visualisation: performance of higher level goals

24. Printing example shows the complexity

26. Benefits of this approach The pursuit of goals and enforcement of constraints that are difficult to represent computationally The following of methods that schedulers find natural The freedom for schedulers to use their intuition

28. earliness tardiness weight weight tardiness

30. Constraints differ between abstraction hierarchies

32. AI model Constraint satisfaction simulation problem of rule management –made-to-order or customised –expensive –difficult to maintain