Hatley ‐ Pirbhai with DOORS Hatley Pirbhai with DOORS Ed Fields efields@ieee.org efields@ieee.org
Importance of Tracking Requirements Importance of Tracking Requirements EE40060 ‐ 1 2
Top ‐ Level Requirements Top Level Requirements • Make ice Make ice – 50 pound blocks – 4 blocks/day, 6 days/week 4 blocks/day 6 days/week – System must be able to grow to produce 200 blocks/day blocks/day • Monitor power usage • Ice loaded into trucks in the morning for l d d k h f delivery 3
Model Functions Model Functions • Hatley ‐ Pirbhai methodology Hatley Pirbhai methodology – Developed by Imtiaz Pirbhai and Derek Hatley as an outgrowth from an outgrowth from in the late 1980s. in the late 1980s – Imtiaz Pirbhai was under contract to Hughes Aircraft Company 1991 ‐ 1994. Died after first year. Aircraft Company 1991 1994. Died after first year. • Using TurboCASE as H ‐ P tool. 4
Context Diagram Context Diagram Water water Source .0 blocks Make of ice and load ice water Truck on/off truck Status • Context Diagram shows system interface with the ‘world’ • Water flows into the system with on/off control • Ice comes out of the system with the system I t f th t ith th t having some knowledge of the truck 5
Requirements Table Requirements Table 1 Make ice 2 Monitor Power Usage 3 Load ice onto trucks 6
Extended Numbering to allow Paragraph Structure h 1 Introduction 2 References 3 Requirements 3.1 3 1 Make ice Make ice 3.2 Monitor Power Usage 3.3 Load ice onto trucks 7
Decompose Context Level Decompose Context Level blocks of ice .1 Make water Ice .3 Load Ice blocks onto of ice trucks water water on/off .2 truck Monitor St t Status power Power Usage power usage per block of block of ice 8
Continue Decomposition, process 3 Continue Decomposition, process 3 .1 1 Check truck is truck position ready for Status of truck ice .2 slide block blocks of ice onto of ice truck block loaded .3 .3 truck is count and ready to total blocks leave on truck 9
DOORS Table DOORS Table 1 Introduction 2 References 3 3 Requirements Requirements 3.1 Make ice The main purpose of this process is to freeze water in 50 lb. blocks. The molds have to be filled with water, the water frozen, the blocks removed from the mold, and then stored for loading onto trucks for delivery. 3.2 Monitor Power Usage This function measures the amount of power used by the system, totals the amount of power from one day to the next over 24 hours, and reports this value. 3.3 Load ice onto trucks When truck is in proper position at loading dock move ready ice onto truck and make sure it is secure When truck is in proper position at loading dock, move ready ice onto truck and make sure it is secure. Only load the appropriate amount of ice onto the truck. 3.3.1 Check position of truck Verify a truck is in a valid position for loading ice. Also insure the truck has enough available cargo capacity for the desired amount of ice. 3.3.2 Slide block of ice onto truck Move blocks of ice onto the truck and secure the load. 3.3.3 Count and total blocks on truck Verify the correct number of blocks are loaded onto the truck. Notify truck driver the loading of the truck is complete is complete. 10
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