Topic 22
Scheduling Systems
Overview
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
Implementation
Scheduling models
Solution methods
System Design
Advanced Planning and Scheduling (APS) system
Enterprise-wide information system (ERP)
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
2
Overview

Context for scheduling systems



Enterprise Resource Planning
Levels of planning
Elements of scheduling systems



Database
Schedule generator
User interface
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
3
ERP Systems

Enterprise Resource Planning (ERP) system

Enterprise wide information system

Single master database

Origins in manufacturing


Computer Integrated Manufacturing (CIM)

Materials Requirement Planning (MRP)
Ties with back office functions

July 11, 2017
Accounting, marketing, manufacturing, etc
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
4
ERP Systems
Materials Requirement
Planning (MRP)
Marketing
and Sales
Database
Scheduling
Product
Definition
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
5
Advanced Planning and
Scheduling (APS) Systems
Database Management
Automatic Schedule Generator
Schedule Editor
Performance Evaluation
Graphical User Interface (GUI)
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
6
Generic or Application Specific

Generic




May require a great deal of customization
Relatively inexpensive but slower
Support from software vendor
Applications specific



Large problems/databases
Specialized scheduling environment
In-house maintenance
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
7
Topic 23
Planning Levels
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
Scope of Scheduling

Scheduling: determining how to use
resources in the optimal manner

Many levels

abstraction of resources


e.g., plants, work stations, machines, tools
time horizon
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
9

Levels of Scheduling
ERP
July 11, 2017

Long-range planning
2-5 years

Middle-range planning
1-2 years

Short-range planning3-6 months

Scheduling
2-6 weeks

Reactive scheduling
1-3 days
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
10
Industry Example: Oracle
Source: http://www.oracle.com/applications/B2B/Planning/index.html?solution.html
Lecture Notes for Planning and Scheduling
July 11, 2017
Prepared by Siggi Olafsson
11
Long-Range Planning

Problems:






Plant expansion
Plant layout
Plant design
Most important: forecasting issues
Lot sizing models used but not very
successfully (see later)
Need stochastic models
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
12
Middle-Range Planning

Problems:


Production smoothing
Logistics

Scheduling successful at this level

Forecasting remains difficult
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
13
Short-Range Planning

Problems:



Material Requirements Planning (MRP)
Setting due dates and release times
MRP




Starts with mid-range production schedule
Known orders & statistical predictions
Obtain master schedule
Assumes infinite capacity and whole day buckets
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
14
Scheduling

Problems:

Job shop routing

Assembly line balancing

Process batch sizing

Given due dates, raw material release time

Typically develop 6 week schedule once a
week
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
15
Reactive Scheduling

Problems






Hot jobs
Down machines
Late material
Make corrections
Human element
Interactive scheduling and
reoptimization
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
16
Hierarchy

Traditional



Top-down
Long-range planning  scheduling
New development


ERP allows greater integration
More interaction
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
17
ERP System Interactions

Advanced Planning and Scheduling


Scheduling
Capacity management
Bill of Materials
Routings
July 11, 2017
ASP
System
Production Schedule
Due Dates
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
18
ERP Systems (example)
MRP
System
What if ?
Complete integration
ASP
System
July 11, 2017
- high priority order
- schedule overtime
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
19
Topic 24
Data & Databases
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
Databases

Custom or commercial database system



Microsoft SQL Server, Oracle, Sybase
Structured Query Language (SQL)
Basic functions



Editing
Sorting
Searching
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
21
Types of Data

Static Data





Number of machines
Layout
Due date
Release date
Dynamic Data




Starting time
Completion time
Sequence of jobs
Tardiness
July 11, 2017


Independent of the schedule
Depend on the schedule
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
22
Job Data
Job Data Type
ID
Name
Type
Quantity Priority
Ready
Due
10
200
Job Instance
2
July 11, 2017
IBM
4
160
2
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
23
Job Object
July 11, 2017
Job ID
ID = 2
Name
Type
Quantity
Priority
Ready
Due
Name = IBM
Type = 4
Quantity = 160
Priority = 2
Ready = 10
Due =200
create
copy
delete
display
create
copy
delete
display
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
24
General Enterprise Data

Plant layout


Resource calendar


Work centers and machines
Shift schedules, holidays, maintenance
schedules
Routing table

Which machines can be used, precedence
constraints
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
25
Topic 25
Schedule Generation
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
Schedule Generation

Algorithm Approach
(This is what we have been doing.)

Knowledge-Based Approach
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
27
Algorithm Approach

Mathematical formulation




decision variables
objectives
constraints
Three phases: Preprocessing
July 11, 2017
Example: 1 ||  w jT j
Calculate tightness of
deadlines
Algorithm
Apply the ATC rule
Postprocessing
Improve sequence
using Tabu search
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
28
Knowledge-Based Approach
Scheduler
knowledge
of system
Rules and
objects
Historical
data


Underlying problem structures
Feasible/preferred solution
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
29
Algorithm Approach
Characteristics

Is mathematical formulation possible?

Rule of thumb: should be applied for
systems with




Large number of jobs
Minimum randomness
Frequent real-time optimization
Consistent general rules
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
30
Knowledge-Based Approach
Characteristics



Any feasible schedule suffices
May be easier to adapt to system
changes
Hybrid of both approaches?


Recent convergence
Unusual to find a system that does not
have some elements of each
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
31
Topic 26
User Interfaces
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
User Interfaces



Very important part of the system
May determine if system is used or not
Several different types




Gantt chart
Dispatch list
Capacity bucket list
Throughput diagram
July 11, 2017

Graphical interfaces
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
33
Gantt Chart


Most popular
Good overview of schedules



Disadvantages


tardy jobs
machine utilization
limited when many jobs/machines
“Drag-and-drop”

cascading/propagation effect,
reoptimization
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
34
Dispatch List

Ordered list of jobs






starting time
machine
processing time
due date, etc.
Unlimited number of jobs
Overview with respect to time limited
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
35
Capacity Buckets




Partition time into slots or buckets
Processing capacity of each machine
known
Percentage of capacity used in each
bucket
Medium to long-range planning
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
36
Throughput Diagram

Total orders





received
produced
shipped
Over time
Information on:


Machine utilization
WIP
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
37
Topic 27
Internet Scheduling
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
E-Scheduling

Information access systems


Information coordination systems


Internet GUI
Information processing systems


Electronic Data Interchange (EDI)
Actual scheduling done over the Internet
Internet scheduling systems
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
39
Information Processing
Systems

Application Service Providers (ASP)




Host enterprise software
Clients access via the Internet
Pay on per-use basis
Advantages:




Low initial cost
System support from ASP
Reaches midsize to smaller enterprises
Hot for ERP, etc.
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
40
Possible Directions

Standardization

Customization
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
41
Internet Scheduling

Network structure



Scheduling server(s)
Local clients
Advantages



Local clients can support GUIs
Server/clients can share data management
Servers can jointly (distributed) solve large
scheduling problems
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
42
Internet System Design
Client
Server
Database
Schedule Information
July 11, 2017
Internet
Server
Client
Database
Process Information
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
43
Division of Labor
Client
Server
Database
Select (suggest) algorithm
Run algorithm
Create schedule display
July 11, 2017
Internet
Server
Client
Database
Formulate problem
(Select algorithm)
(Run algorithm)
Display schedule
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
44
New Algorithm Generation
First Algorithm
Main
Algorithm
Library
Composite Algorithm
Internet
Server
July 11, 2017
Algorithm
Generator
Local
Algorithm
Library
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
Client
45
Tools

Existing Internet support





Markup Languages: HTML, XML, DHTML
Java Applets
Scripting: JavaScript, VBScript, etc.
Active Server Pages (ASP)
Browsers



Netscape
Internet Explorer (IE)
Compatibility
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
46
Applying the Tools
Client
Server
Database
ASP
VBScript
- Select algorithm
Java (other)
- Run algorithm
July 11, 2017
Internet
Server
Client
Database
HTML
- XML for scheduling
JavaScript
- Define problem
Java Applets
- Display results
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
47
Discussion


Future of all enterprise software
Advantages


Higher speed at lower cost
Challenges




Ownership of data/systems
Customization versus standardization
Security
Effective designs? Collaboration?
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
48
Future of Scheduling





System development
E-Scheduling
Integration with other function
Availability of data (mining?)
Computing power
 Increased importance of scheduling
July 11, 2017
Lecture Notes for Planning and Scheduling
Prepared by Siggi Olafsson
49