Appendix D – Defect Inspection System

TABLE OF CONTENTS

1. Background

2. Context Schema

3. Event List

4. Entity Relationship Diagram

5. Leveled Set of Schemas

6. Data Dictionary

7. Transformation Specifications

Problem Statement

The purpose of the defect inspection system is to chop rolls of metal foil into sheets and to sort the sheets into two bins according to a preselected product standard. Those that meet the standard go into one bin; those that do not go into another.

The system is run by a supervisor and a number of operators. The supervisor is responsible for the overall running of the system including selecting product standards, configuring each of the production surfaces, and selecting sheet sizes.

The four production surfaces are monitored by the operators; presently each operator is responsible for two surfaces. The operators can start and stop a production surface. They also wheel out full bins and replace them with empty ones.

Each production surface is equipped with a scanner, a chopper, and two air jets. Any configuration of this equipment is workable, so long as both air jets follow the chopper. The supervisor tells the system which configuration has been set up on each surface.

The scanner operates by reading the amount of light reflected from the foil. A large percentage of the reflected light for squares scanned by the scanner must be between certain values, as defined by the product standard, for the foil to be deemed “good,” otherwise the sheet must be rejected as “bad.” Irregularities in the foil will tend to produce values outside the specific range. The scanner returns data for each of the squares by organizing what it “sees” into lanes that run perpendicular to the direction of travel of the foil. Data is produced for each square in the lane, preceded by the lane numbers.

A chopper for each surface can be commanded to drop, thus cutting the roll into sheets. The chopper raises itself automatically once it has chopped the foil. The chopper must be controlled to chop the foil into sheets of constant size for a particular run. The foil may be chopped before it is scanned.

There are two air jets; one pushes the foil to the left, the other to the right. By custom, good foil is always thrown to the right.

The foil is moved along the production surface by a conveyer belt system that can be started and stopped by the operator (to start or stop the production surface is, in fact, to start or stop the conveyer system). A shaft encoder is connected to the drive roll in the belt system; each quarter revolution of the drive roll will produce a pulse from the shaft encoder. The resolution of the system is sufficient to be able to cut sheets to lengths measured in units of shaft encoder pulses.

Figure D.BKG Defect Inspection System Equipment Configuration.

Figure D.CS Context Schema.

Event List

Sheet enters system.

Edge of sheet is under scanner.

Edge of sheet is under chopper.

Edge of sheet is under good airjet.

Edge of sheet is under bad airjet.

Supervisor defines product standard for production run.

Supervisor configures inspection surface.

Operator starts system.

Operator stops system.

Supervisor changes sheet size.

Figure D.ER Entity Relationship Diagram.

Figure D.O Inspect Foil.

Figure D.I Manage Product Specification and Configuration.

Figure D.2 Monitor Sheet Production.

Figure D.2.1 Monitor Inspection Surface.

Figure D.2.1.1 Control Inspection Surfaces.

Figure D.2.2 Monitor Sheet Movement.

Figure D.2.2.1 Control Sheet Movement.

Figure D.2.3 Monitor Sheet Scanning.

Figure D.2.3.1 Control Sheet Scanning.

Data Dictionary

bad-whoosh	=	*signal to open valve on bad airjet for fixed interval*
bad-airjet-location	=	**
		*values : 1-2048; units : shaft encoder pulses*
chop	=	*signal to release the chopper*
chopper-location	=	**
		*values : 1-2048; units : shaft encoder pulses*
current-equipment -configuration	=	equipment-configuration
equipment-configuration	=	*the arrangement of the equipment on a single inspection surface*
		inspection-surface-number + scanner-location + chopper-location + good-airjet-location + bad-airjet-location
good-airjet-location		**
		*values : 1-2048; units : shaft encoder pulses*
good-whoosh	=	signal to open valve on good airjet for fixed interval
high-limit	=	*high scanner data limit for a given product standard*
		*values: 1-1000*
illegal-change-message	=	[unable-to-change-sheet size-message|unable-to-change-configuration-message|unable-to-change-product-message]
inspection-surface	=	*definition of equipment configuration for a single inspection surface*
		@inspection-surface-number + scanner-location + chopper-location + good-airjet-location + bad-airjet-location + status
inspection-surfaces	=	**
		{inspection-surface}
lane-number	=	*relative location of a strip running perpendicular to the length of the inspection surface as viewed by the scanner*
		*values : 1-512*
location	=	**
		*values : 1-2048; units : shaft encoder pulses*
low-limit	=	*low scanner data limit for a given product standard*
		values : 1-1000*
product-change	=	*the definition of which product is to be run on a given inspection surface*
		inspection-surface-number + product-id
product-id	=	**
production-run	=	*definition of what is to be produced on a single inspection surface*
		@product-standard-ref + @inspection-surface-ref + sheet-size
production-runs		**
		{production-run}
product-standard	=	*definition of acceptable scanner data values*
		@product-id + high-limit + low-limit
product-standards	=	**
		{product-standard}
scanner-data	=	*scanner data for lane-sector combinations visible to scanner*
		512 {lane-number + 512 { sector-values 512 }512
scanner-location	=	**
		*values : 1-2048; units : shaft encoder pulses*
shaft-encoder-pulse	=	*signal that a quarter turn has occurred on the conveyer system wheels*
sheet	=	**
		@sheet-id + defect-status
sheet-enters	=	**
sheet-location	=	**
		@sheet-id + @inspection-surface-ref 4-location
sheet-locations	=	*the set of locations of all sheets on all surfaces*
		{sheet-location}
sheets	=	*the set of sheets in the system between entry to an inspection surface and ejection by an airjet*
		{sheet}
sheet-size	=	**
		*values : 1-128; units : shaft encoder pulses*
sheet-size-data	=	*the size of a sheet to be cut on a given run*
		inspection-surface-number + sheet-size
sheet-under-airjet	=	[sheet-under-good-airjet]
sheet-under-bad-airjet	=	**
sheet-under-good-airjet	=	**
sheet-under-scanner	=	**
start	=	*signal to start system*
start-belt	=	**
status	=	*status of inspection surface*
		*values [ on | off ]*
stop	=	*signal to stop system*
stop-belt	=	**
unable-to-change-configuration-message	=	**
unable-to-change-product-message	=	**
unable-to-change-sheet-size-message	=	**

Transformation Specifications

1.1 Change Current Product

Precondition 1

PRODUCT CHANGE occurs

and STATUS of referenced INSPECTION SURFACE is “off;”

Postcondition 1

the PRODUCTION RUN referencing the INSPECTION SURFACE indicated by PRODUCT CHANGE contains a reference to the provided PRODUCT STANDARD

Precondition 2

PRODUCT CHANGE occurs

and STATUS of referenced INSPECTION SURFACE is “on”

Postcondition 2

UNABLE TO CHANGE PRODUCT MESSAGE is produced

1.2 Change Configuration

Precondition 1

EQUIPMENT CONFIGURATION occurs

and  STATUS of referenced INSPECTION SURFACE is “off”

and  both SCANNER LOCATION and CHOPPER LOCATION are less than both GOOD AIR JET LOCATION and BAD AIR JET LOCATIONS

Postcondition 1

the referenced INSPECTION SURFACE contains the data from EQUIPMENT CONFIGURATION

and  CURRENT EQUIPMENT CONFIGURATION corresponds to EQUIPMENT CONFIGURATION

Precondition 2

EQUIPMENT CONFIGURATION occurs

and  STATUS of referenced INSPECTION SURFACE is “off”

and  some part of Precondition 1 does not hold

Postcondition 2

CURRENT EQUIPMENT CONFIGURATION corresponds to referenced INSPECTION SURFACE

and  UNABLE TO CHANGE CONFIGURATION MESSAGE occurs

Precondition 3

EQUIPMENT CONFIGURATION occurs

and  STATUS of referenced INSPECTION SURFACE is “on”

Postcondition 3

UNABLE TO CHANGE CONFIGURATION MESSAGE occurs

1.3 Enter Sheet Size

Precondition 1

SHEET SIZE DATA occurs

and  STATUS of referenced INSPECTION SURFACE is “off”

Postcondition 1

referenced PRODUCTION RUN contains the SHEET SIZE from SHEET SIZE DATA

Precondition 2

SHEET SIZE DATA occurs

and  STATUS or referenced INSPECTION SURFACE is “on”

Postcondition 2

UNABLE TO CHANGE SHEET SIZE MESSAGE occurs

2.1.2 Mark Running

Precondition 1

none

Postcondition 1

STATUS of INSPECTION SURFACE is “on”

2.1.3 Mark Stopped

Precondition 1

none

Postcondition 1

STATUS of INSPECTION SURFACE is “off”

2.2.2 Update Sheet Locations

Precondition 1

none

Postcondition 1

the LOCATION for every SHEET-LOCATION referencing the INSPECTION SURFACE is greater by 1

2.2.3 Check Sheet Statuses

Precondition 1

There is a SHEET whose LOCATION is one SHEET SIZE from the start of the INSPECTION SURFACE

Postcondition 1

SHEET ENTERS is produced

Precondition 2

There is a SHEET whose LOCATION is equal to the SCANNER LOCATION

Postcondition 2

SHEET UNDER SCANNER is produced

Precondition 3

There is a SHEET whose LOCATION is equal to GOOD AIRJET LOCATION

Postcondition 3

SHEET UNDER GOOD AIRJET is produced

Precondition 4

There is a SHEET whose LOCATION is equal to BAD AIRJET LOCATION

Postcondition 4

SHEET UNDER BAD AIRJET is produced

Precondition 5

There is a SHEET whose LOCATION is equal to CHOPPER LOCATION

Postcondition 5

CHOP is produced

2.3.2 Scan Sheet

Local term: USEFUL DATA is the SECTOR VALUES for each LANE with LANE NUMBER between 1 and SHEET SIZE for the PRODUCTION RUN referenced by the INSPECTION SURFACE

Precondition 1

SCANNER DATA occurs for an INSPECTION SURFACE

and  95% of the SECTOR VALUES of USEFUL DATA are between HIGH LIMIT and LOW LIMIT of the PRODUCT STANDARD referenced by the PRODUCTION RUN for the INSPECTION SURFACE

Postcondition 1

DEFECT STATUS is “good” for the SHEET whose SHEET LOCATION matches the SCANNER LOCATION for the INSPECTION SURFACE

Precondition 2

SCANNER DATA occurs for an INSPECTION SURFACE

and  Precondition 1 does not hold

Postcondition 2

DEFECT STATUS is “bad” for the SHEET whose SHEET LOCATION matches the SCANNER LOCATION for the INSPECTION SURFACE

2.3.3 Add Sheet

Precondition 1

none

Postcondition 1

There is a SHEET whose ID is 1 greater than the previously highest SHEET ID and whose DEFECT STATUS is “unknown”

and  There is a SHEET LOCATION referencing the new SHEET and the INSPECTION SURFACE whose LOCATION is O

2.3.4 Dispatch Sheet

Local term: MATCHING GOOD SHEET is a SHEET whose SHEET LOCATION matches GOOD AIRJET LOCATION and whose DEFECT STATUS is “good”

Local term: MATCHING BAD SHEET is a SHEET whose SHEET LOCATION matches BAD AIRJET LOCATION and whose DEFECT STATUS is “bad”

Precondition 1

MATCHING GOOD SHEET exists

Postcondition 1

GOOD WHOOSH is produced

and  the SHEET and SHEET LOCATION referenced by MATCHING GOOD SHEET do not exist

Precondition 2

MATCHING BAD SHEET exists

Postcondition 2

BAD WHOOSH is produced

and  the SHEET and SHEET LOCATION referenced by MATCHING BAD SHEET do not exist