1. 1 When Theory Crashed into Reality Yossi Rissin Chief Executive Officer, Visopt B.V Roman Barták Chief Scientist, Visopt B.V.

2. 2 What is the talk about? Planning vs. scheduling Practice Theory

3. 3 Planners from Venus Researchers from Mars

4. 4 A theoretical factory O M machines O N jobs -each job consists of O i operations with the precedence relation (dedicated machines for operations) O Job Shop Scheduling (JCC) -Flow Shop Scheduling -Open Shop Scheduling

5. 5 JSS in Practice? „I have never seen a Job Shop Scheduling Problem in practice“ Wim Nuiten, ILOG

6. 6 The Human Factor (Planners & plant personnel are motivated by:) O Pride. No disclosure of mistakes, problems and weaknesses. O Position in the organisation. Position is protected by being nice to superiors, serving many masters at once, gaining professional respect. O Future security. No disclosure of knowledge, development of organisation dependency.

7. 7 The Human Factor (Planners & plant personnel are characterised by:) O Politics. Internal politics and power plays are key factor in decision taking. O Inconsistency. A human being is tend to inconsistency and easily affected by mood, environment and psychology pressure. O Unexpected. Human behaviour can be determined and can be foreseen just by statistical methods (big numbers, long periods, distributions, etc.)

8. 8 The Ideal Scheduling Projects O Fully automatic factory based on robots and AGV’s -Engineering oriented -No one to argue with -No one knows better -More visibility, less surprises and fluctuations O New factory, not operating yet -Very stable, no fluctuations -No previous “know-how” -No old rules and procedures -No bad habits -No day-to-day-reality to confront the theory

9. 9 Points Of View O Planners -The planner’s world consists of products and their flow -“how can I produce this product now, and this one and that one…” -“How can I satisfy Mr. X from sales and Mr. Y from the plant and the customer at the same time, without getting into new troubles…” O Academy -The engineer/researcher world consists of resources and their usage -“How can I use the resources to get max X and min Y…” -“How can I get, using objective metrics, a plan that for the long term, will improve the plant efficiency…”

10. 10 Not Invented Here O “We are different…” -Means, what you know is useless here O “Outsiders cannot understand it, it takes a lot of time…” -Means, you have to listen to us or to spend part of your life here O “Methods that suite others cannot implemented here…” -Means, your experience and knowledge are impressive, but you have to start from scratch

11. 11 Visopt View O Visual Modelling Language

12. 12 Inside Visopt O Complex resources load heat unload clean cool O General item flow N-to-N relations Alternative recipesRecycling cleanloadheatunloadloadheatunloadcoolclean

13. 13 Quality Issues

14. 14 Theoretical Objectives O Minimise makespan O Minimise lateness (tardiness) O Minimise earliness O Minimise the number of set-ups O Maximise resource utilisation O...

15. 15 Quality Definition O Quality metrics by the user/planner -“It should looks like the schedules I am doing…” -“Good plan should resemble those I use to make manually…” -“In order to produce good plan you have to follow my rules, know-how, procedures…” -Good plan is a one that can be ‘sold’ to production people easily O Most of times there are no history records of the manual plans to analyse their efficiency!

16. 16 Visopt View O Understand the reason by asking Why! minimise makespan minimise lateness minimise earliness minimise number of set-ups maximise resource utilisation... minimise makespan minimise lateness minimise earliness minimise number of set-ups maximise resource utilisation... more satisfied demands penalty for delays storing cost expensive set-ups fix expenses So what is the common objective? M O N E Y minimise costmaximise profit In Visopt we minimise cost (= maximise profit).

17. 17 Bridging the Gap Lessons learned

18. 18 The Common Language O The planner tells a “story” – how to produce a given product or product family, but cannot follow what was understood -Tables and fields say nothing to the planner and not resemble his world O Visual modelling is the key – same, simple language for the user and the computer – the ability to draw the user story

19. 19 Best Is Worse O “The Worst Enemy Of The Good Is The Best” -A very good plan (based on objective metrics) delivered after three hours is not relevant anymore – the factory is not the one it was few hours ago O The art of real-life scheduling is to deliver a plan which is good enough and fast enough: -Good enough – the user cannot improve it in reasonable time -Fast enough – depends on the plant dynamics. One hour can be too late for one plant and very fast to another

20. 20 The Cure Is The Pain O Most manual planning methods that are considered as “know-how” are not relevant to automated scheduling… O What is considered as the “solid true” (Cure), is many times simplifications of reality to enable the manual scheduling (The pain) O Extract the real knowledge from the overall know-how with the help of plant experts -Always ask Why, for everything, and never accept an answer such as “this is the way to do it” -If there is no solid reason behind the “fact” – ignore it

21. 21 Scheduling Is Knowledge Handling O Scheduling is not mathematics, but first of all a knowledge handling process -Capturing the real knowledge -Mapping the knowledge so the user can verify and update it -Process it concerning its elusive nature -Understand and overcome the accurate mathematical metrics when dealing with knowledge

22. 22 What is the real difference? O 2 slides per hour talk O only three words are different on these slides O 78 slides per hour talk Based on „real-life“ data (PACT 96)! PractitionerResearcher

23. 23 @ Thank you! Yossi Rissin yossi.rissin@visopt.com Roman Barták bartak@visopt.com