Overcoming Customer Constraints on Requirements Documents Presented by: Robert Smole Presented by: Robert Smole November 5, 2008 Sub-Optimization of Systems Engineering

1 Agenda Introduction Problem Approach Results Wrap Up

2 Introduction Systems Engineering –Means to enable the realization of successful systems – best practices –Considers both the business and the technical needs of all customers - constraints What happens when the business needs constrain the best practices? Systems Engineering –Means to enable the realization of successful systems – best practices –Considers both the business and the technical needs of all customers - constraints What happens when the business needs constrain the best practices?

3 Why Sub-Optimal? Find a balance. Approach: Sub-optimal SE. Agenda: Communicate the value of SE. Goal: …to realize a successful system. Find a balance. Approach: Sub-optimal SE. Agenda: Communicate the value of SE. Goal: …to realize a successful system. Systems Engineering Best Practices Customer Constraints

4 Size: Length-1092ft, Weight- 97,000tons Cost: Approx. $5-6 Billion Construction time: 6-7 years Design time: Approx 6 years from Concept A mobile, nuclear powered, survivable, sea-based super structure, capable of accommodating approx 5000 personnel, managing 75+ air combat vehicles, and conducting joint operations. Nimitz Class CVN HIGHLY COMPLEX AND CHALLENGING PROGRAMS DEMAND SYSTEMS ENGINEERING

5 Requirements Analysis Requirements Model R Functional Analysis Define high level FA from ORD Define mission/operational performance Decompose functions to lowest level Allocate performance requirements to functions Develop FFBDs Develop Operational Threads (sortie) Operational Scenarios, Conceptual Behavior Models F1 F5 F2F3 F4 Physical Architecture Analysis Define System Structure Define Internal/External Interfaces Determine Island Alternatives Establish product baselines Define system design constraints Allocate functions to systems/components Common Island Component Models Components Interfaces System Analyze Design & Assess Risk Cost Assessment Conduct trade studies Select Best Design Solution Automatic Document Generation Provide Metrics Reports Product Evaluation and Document Generation Analysis Results SRDs Determine common missions Review top level requirements documents Decompose ORD Derive Ship system Requirements Flowdown to system requirements Derive Functional / Performance Requirements R2R1 R1-1 NGSB-NN: Model-Based SE Approach

6 Does our system as-designed and as-built meet the system requirements as-validated? Verification Develop Physical Solution Develop Functional Solution Perform Requirements Analysis Requirements Process Does the customer agree with our interpretation of the requirements? Validation

7 Problem Update a System Requirements Document Not configuration managed within the CASE tool. Contained some or all of: will, shall, may, & should within requirement text. Requirements within functional statements. Requirements not singular (more than one shall). Requirements not stand alone. –Definitions within the body of the document, not in appendix. –SRD used an outline format - multiple indents. Interface requirements not mapped to interfaces on diagram. Update a System Requirements Document Not configuration managed within the CASE tool. Contained some or all of: will, shall, may, & should within requirement text. Requirements within functional statements. Requirements not singular (more than one shall). Requirements not stand alone. –Definitions within the body of the document, not in appendix. –SRD used an outline format - multiple indents. Interface requirements not mapped to interfaces on diagram.

8 Communicate Function Function 1 Function 2 Communicate Orders 3 Function 4 Function 5 AND

9 Improper Use of the CASE Tool Function 1 Function 2 Communicate Orders 3 Function 4 Function 5 Requirement(s) Liabilities: Traceability, Verification, Decomposition

10 Requirements Imbedded within Functions Communicate Orders 1)The _____ subsystem shall be the primary means of communicating orders. 2)The _____ subsystem with interfaces to the _____ shall provide supplementary communications. a)Main Deck Communications Capability 1)The _____ subsystem shall be the primary means of communication for the coordination of operations on the Main Deck. 2)The _____ subsystem with interfaces to the _____ shall provide supplementary communications. b)2nd Deck Communications Capability 1)The _____ subsystem shall be the primary means of communication for the coordination of operations on the 2nd Deck. 2)The _____ subsystem with interfaces to the _____ shall provide supplementary communications. c)Engine Room Communications Capability 1)The _____ subsystem shall be the primary means of communication for the coordination of operations in the Engine Room. 2)The _____ subsystem with interfaces to the _____ shall provide supplementary communications Communicate Orders 1)The _____ subsystem shall be the primary means of communicating orders. 2)The _____ subsystem with interfaces to the _____ shall provide supplementary communications. a)Main Deck Communications Capability 1)The _____ subsystem shall be the primary means of communication for the coordination of operations on the Main Deck. 2)The _____ subsystem with interfaces to the _____ shall provide supplementary communications. b)2nd Deck Communications Capability 1)The _____ subsystem shall be the primary means of communication for the coordination of operations on the 2nd Deck. 2)The _____ subsystem with interfaces to the _____ shall provide supplementary communications. c)Engine Room Communications Capability 1)The _____ subsystem shall be the primary means of communication for the coordination of operations in the Engine Room. 2)The _____ subsystem with interfaces to the _____ shall provide supplementary communications.

11 Constraints The overall document format and layout had to remain consistent with the original document which was not consistent with standard SRD formatting. Definitions and lead-in statements had to remain in their relative location (could not move the definitions to an appendix). May was acceptable - there are some design targets that are not hard requirements (they dont have to meet these). The overall document format and layout had to remain consistent with the original document which was not consistent with standard SRD formatting. Definitions and lead-in statements had to remain in their relative location (could not move the definitions to an appendix). May was acceptable - there are some design targets that are not hard requirements (they dont have to meet these).

12 Approach Moved all the requirements from Word to Excel. Parsed the requirements from the functions. Separated multiple shall statements. (singular requirements) Placed definitions in Requirement Objects and marked the Verification Method as n/a to identify it as not a requirement. Standardized on the use of shall to denote requirements. Moved all the requirements from Word to Excel. Parsed the requirements from the functions. Separated multiple shall statements. (singular requirements) Placed definitions in Requirement Objects and marked the Verification Method as n/a to identify it as not a requirement. Standardized on the use of shall to denote requirements.

13 Approach Allowed the use of may for design targets (these are not requirements). Used the spreadsheet to provide a comparison to the baseline. Decided on an iterative approach to fix the SRD. –Further changes to structure (ie, interface linking) in future revisions. Migrated requirements to the CASE Tool (Cradle) and used this tool to generate the Rev B SRD. Allowed the use of may for design targets (these are not requirements). Used the spreadsheet to provide a comparison to the baseline. Decided on an iterative approach to fix the SRD. –Further changes to structure (ie, interface linking) in future revisions. Migrated requirements to the CASE Tool (Cradle) and used this tool to generate the Rev B SRD.

14 Result (example) Communicate Orders This function communicates orders a) Communicate Orders - 1 The _____ subsystem shall be the primary means of communicating orders. b) Communicate Orders - 2 The _____ subsystem with interfaces to the _____ shall provide supplementary communications. c) Main Deck Communications Capability - 1 The _____ subsystem shall be the primary means of communication for the coordination of operations on the Main Deck. d) Main Deck Communications Capability - 2 The _____ subsystem with interfaces to the _____ shall provide supplementary communications. e) 2nd Deck Communications Capability - 1 The _____ subsystem shall be the primary means of communication for the coordination of operations on the 2nd Deck. … Communicate Orders This function communicates orders a) Communicate Orders - 1 The _____ subsystem shall be the primary means of communicating orders. b) Communicate Orders - 2 The _____ subsystem with interfaces to the _____ shall provide supplementary communications. c) Main Deck Communications Capability - 1 The _____ subsystem shall be the primary means of communication for the coordination of operations on the Main Deck. d) Main Deck Communications Capability - 2 The _____ subsystem with interfaces to the _____ shall provide supplementary communications. e) 2nd Deck Communications Capability - 1 The _____ subsystem shall be the primary means of communication for the coordination of operations on the 2nd Deck. …

15 Communicate Function - Revisited Function 1 Function 2 Communicate Orders 3 Function 4 Function 5 AND

16 Proper Use of the CASE Tool Function 1 Function 2 Communicate Orders 3 Function 4 Function 5 Requirement(s) Allows: Traceability, Verification, Decomposition

17 Wrap Up Considerations –New Design? –Roll-over Design? –Commercially Available Products? –Integrating Other Systems? –System Complexity? Essentials –Interface Requirements. –Traceability. –Verification. Non-Essentials –Document Format/Layout. One step at a time = progress toward full SE Considerations –New Design? –Roll-over Design? –Commercially Available Products? –Integrating Other Systems? –System Complexity? Essentials –Interface Requirements. –Traceability. –Verification. Non-Essentials –Document Format/Layout. One step at a time = progress toward full SE

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