Regulation Management in Resource Scheduling Problems with fREeDOM - PowerPoint PPT Presentation

Regulation Management in Resource Scheduling Problems with fREeDOM System Christos Goumopoulos Dr. Electrical and Computer Engineering 2 nd AMORE Seminar, 30 Oct - 3 Nov, 2001, Patras, Hellas

Outline ◆ A few words about LYSEIS Ltd ◆ Resource Scheduling in Airline Industry ◆ Modeling Regulations with fREeDOM ◆ Complete Regulation Management ◆ Conclusions C. Goumopoulos - LYSEIS Ltd AITS 2

LYSEIS Ltd AITS ◆ Main figures – Spin-off company established in 1998 – 3 CS PhD associates + external collaborators – Patras Scientific Park building (HQ) ◆ Products and services – fREeDOM system – RIDE (Ruleset Integrated Development Environment) – Crew Rescheduling System (under development) – Shift scheduling for call centers (under development) – Consulting for developing resource management systems – Technical & educational support C. Goumopoulos - LYSEIS Ltd AITS 3

Planning Processes in the Airline Industry ◆ Timetable construction – All the flights the airline decides to operate ◆ Aircraft scheduling (Fleet Assignment) – Optimal assignment of a specific aircraft type to every flight, satisfying various constraints ◆ Crew scheduling – Optimal assignment of crews to every flight, satisfying a large number of regulations ◆ Day-to-day resource rescheduling – Optimal confrontation of unexpected events during the execution of the program, satisfying all the regulations C. Goumopoulos - LYSEIS Ltd AITS 4

Terminology rotation ( pairing ) Shift # 1 Shift # 2 A shift (duty period) is a legal ◆ layover sequence of legs A flight leg is the basic indivisible planning activity ◆ involving a single departure and a single arrival - it is Each shift includes the briefing and ◆ LH162 defined by the place and time of departure and arrival the debriefing of crew members in the beginning and in the end of the The duration of a leg and the assigned aircraft type ◆ FRA MUC MUC HAM HAM STR STR MUC MUC ATH ATH FRA shift, respectively determine the required crew complement 9:00 10:00 11:00 13:00 14:00 15:00 8:00 9:00 10:00 14:45 16:00 19:30 Briefing Debriefing Briefing Debriefing (60 mins) (15 mins) Every rotation departs and returns to the same crew base (airport) ◆ A legal rotation is assigned indivisible to one or more crew members ◆ C. Goumopoulos - LYSEIS Ltd AITS 5

MODELING REGULATIONS WITH fREeDOM

Regulations to Model ◆ Fundamental legality rules – safety regulations (governmental, international) – union contracts ◆ Operational stability rules – company policies ◆ Quality rules – soft rules to improve the quality of schedules ◆ Rules to improve scheduling application performance – special pruning rules ◆ Complex cost functions for the optimization problems C. Goumopoulos - LYSEIS Ltd AITS 7

Rule Complexity Example Return to homebase (hb) yes no timezone (tz) AND tz_diff for all duty >= 4 h ? Minimum Rest Period Calculation Rule yes no time away yes no tz_diff in duty >= 4 h ? from hb < Depending on factors such as: 60 h ? the duration of the preceding ◆ MRP = MRP = MRP1 = max( prev(duty), 14) MRP1 = max( prev(duty), 11) max_htz_diff * 4 max_htz_diff * 8 shift if the preceding shift ◆ contains a split (includes a yes no yes no is previous rest is previous rest break from 3 to 11 hours) reduced? reduced? if the preceding rest period ◆ yes no yes no reduction = reduction = was a reduced one MRP = MRP1 + MRP2 = MRP1 + MRP1 - rest MRP1 - rest prev(reduction) prev(reduction) is rest reduced? is rest reduced? the traveling time in ground ◆ MRP = MRP1 MRP2 = MRP1 the timezone difference MRP = ◆ MRP2= (permission for (permission for max(MRP1-3, 14) max(MRP1-3, 11) reduce) reduce) between the place of starting the shift or the parent rotation and the place ending yes no yes no travelling > 2 ? travelling > 2 ? the current shift MRP = MRP2 + MRP = MRP2 + MRP = MRP2 MRP = MRP2 C. Goumopoulos - LYSEIS Ltd AITS (travelling - 2) (travelling - 2) 8

How to Model the Regulations? ◆ Hard-coding the regulations in the scheduling application has disadvantages: – application integrity risk in case of a rule change – changing the rules requires expert programmers – large maintenance cost ◆ Handling the regulations with an autonomous system has advantages: – user-oriented (less cost, flexibility) – vendor-oriented (less maintenance effort, application safety, easier deployment to new clients) C. Goumopoulos - LYSEIS Ltd AITS 9

The fREeDOM System ◆ fREeDOM ( f ast RE gulation D efinition and O n-line M anipulation) is a flexible s/w component for developing Regulation Handling Systems ◆ Complete regulation management – Allows the immediate adaptation of scheduling systems in regulation changes ◆ Addressed to any company that needs to have its rules under control – Expression and update of rules from the end-user ◆ Prototype system was developed at Computer Laboratory of Electrical and Computer Engineering Department at University of Patras (DAYSY ESPRIT project) C. Goumopoulos - LYSEIS Ltd AITS 10

Modeling Language ◆ Declarative special purpose modeling language (emphasizes on WHAT not on HOW) ◆ High level language semantics closely related to the user terms C. Goumopoulos - LYSEIS Ltd AITS 11

fREeDOM Object Meta-model Flying Fixed Activity Chain Includes scheduling problem TimeWindow TimeWindow ◆ domain abstractions: start ! Rule end TimeWindow • Activity Composition • Property Calculation Activity Property • Property Constraint Resource ! Activity • Primitive Primitive Primitive Composite Derived Property Activity Activity Property • Composite ! Property Activity Property Property Composition Calculation Constraint • Primitive Rule Rule Rule • Derived ! Timewindow Ruleset Rule C. Goumopoulos - LYSEIS Ltd AITS 12

Airline Object Model (part of) requires Activity Activity is involved Chain request requires crew- qualification complement start_date end_date ... Crew has a Member Type Stand Training Rotation Simulation Vacation By is qualified {ordered Crew } Member requires Shift Rest qualification start_date end_date ... {ordered } Briefing Leg Transit Debriefing has home base Deadhead On Duty departure arrival City belongs to Airport restrictions visa language Aircraft Type restrictions Aircraft air lane size is involved C. Goumopoulos - LYSEIS Ltd AITS 13

Regulation Categories (part of) Ruleset Rule ... Time Window Rotation Duty Transit Rest Costing Landing ... Group Group Group Group Group group Group Rest restrictions homebase min/max ... Transit restrictions no of breaks min/max ... Duty restrictions flight time duty time landings ... Rotation restrictions restrictions flight time hotel cost duty time transportation cost landings per’ diem cost ... tickets cost revenue lost Time Window crew meals cost overtime payment restrictions ... start end "8 rest hrs in 24 hrs" "36 rest hrs in 7 days" C. Goumopoulos - LYSEIS Ltd AITS "900 flight hrs in a year" 14 Activity ...

Regulation Modeling Example Activity Type Declaration ACTI VI TY shift NEIGHBOURS : shift; COMPONENTS : leg; PROPERTIES : duty_period : trel; CONSTRAINTS: max_duty_period; END Activity Composition Rule COMPOSI TI ON OF shift RULE: ((departure - (of prev leg arrival) > 11:00) Shift 1 Shift 2 or >11:00 … ((of parent shift (duty_period > 12:00)) and FRA MUC MUC HAM HAM STR STR MUC 9:00 10:00 11:00 13:00 14:00 15:00 8:00 9:00 (departure - (of prev leg arrival) > 08:00))); END duty_period PROPERTY duty_period OF shift Property Calculation Rule RULE: (of last leg arrival) - (of first leg departure); «shift duration» ‘property calculation expression’ END CONSTRAI NT max_duty_period OF shift Property Constraint Rule «Maximum duration of a shift must be 14 hrs» RULE: duty_period < = 14:00 END C. Goumopoulos - LYSEIS Ltd AITS 15

Data Types ◆ Conventional – integer, boolean, float, string ◆ Relative time – Example: ‘2:00’ ◆ Absolute time – Example: ‘1 Jan 2001 0:00’ ◆ Set – Example: SET Hellenic_airports = “ATH”, “SKG”, “JSI” C. Goumopoulos - LYSEIS Ltd AITS 16

Aggregation Operators ◆ Calculate a value aggregating a property/expression over all the component activities of a composite activity SUM AVG MIN MAX COUNT ALL ANY – The range of participating component activities can be controlled with the use of a WHERE condition The calculation can prematurely ended with the use of a WHILE condition – – Direct aggregation in any level of the implied aggregation hierarchy Flying time in a shift SUM fly_time OVER leg; Flying time in a shift based SUM fly_time OVER leg only on flight legs departing WHERE (departure_airport I N Hellenic_airports); from Hellenic airports Flying time in a shift till the SUM fly_time OVER leg first Hellenic airport WHI LE not (departure_airport I N Hellenic_airports); C. Goumopoulos - LYSEIS Ltd AITS 17