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A Systems Engineering Approach For Balancing Powered Trailer Requirements

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  1. “A Systems Engineering Approach For Balancing Powered Trailer Requirements” Dana Peterson (CSEP Acq) dpeterson@drs-ssi.com (314) 553-4599

  2. Purpose of Presentation • Illustrate a sample of Systems Engineering tools used on the Powered Trailer project to: • Resolve requirement issues • Understand relationships between requirements • Prioritize requirements • Get consensus on the best technology options • Provide the best “balanced” overall solution INCOSE BRIEF @ DRS Technologies

  3. Powered Trailer Project Goals • Improve combined truck and trailer grade climbing and mobility in soft soil terrain conditions • Provide cargo and health status reporting over the C4I network • Provide limited trailer self-mobility for climbing aircraft/ship ramps under operator control • Provide on-board DC/AC export power for powering shelters and other equipment Powered Trailer Focus is on Trailer Drive Technologies INCOSE BRIEF @ DRS Technologies

  4. Sample SE Tools • Requirements Traceability/ Rationale Matrix (RTRM) • N2 Diagram • Analytic Hierarchy Process (AHP) • Quality Function Deployment (QFD) • Morphological Analysis (MA) • Architecture Views • Trade Study • Sensitivity Analysis • Affinity Diagram • Tree Diagram • Fishbone Diagram • Digraph • Blueprinting • Arrow Diagram • Matrix Diagram • Relations Diagram • Process Decision Program Chart • Flow Diagram • Context Diagram • Pugh Matrix • Specification INCOSE BRIEF @ DRS Technologies

  5. Systems Engineering Approach Requirements Traceability/ Rationale Matrix (RTRM) Requirement Prioritization QFDHouse Of Quality Performance Spec User Requirements AHP MA Technology Options Mobility Analysis Power Trailer Design Alternatives Trade Studies -Performance -Payload -C-130 Transport -R&M -Cost -Schedule Legend AHP = Analytical Hierarchy Process QFD = Quality Function Deployment MA = Morphological Analysis Sensitivity Analysis Preferred Solution An Iterative Hierarchical Process That Provides the Best Overall Requirements Balance

  6. Multi-Attribute Criteria Problem • Many requirements in diverse functional areas • A lot of stakeholders involved • Tools are needed to balance requirements and validate concept prior to project execution • Cost and schedule are receiving a lot more attention Cost Schedule Performance INCOSE BRIEF @ DRS Technologies

  7. Solution Synthesis is Becoming More Challenging Part Obsolescence Technology Advances Design for Adaptability Reorganization Cultural Robust Design Techniques Economic Spiral Development Rapid Response Open Architecture Cost Six Sigma Schedule Security Modular Systems Approach Agile Design Political Performance Design To Cost People Resources Design for Dynamic Value Company Mergers Eco-Consciousness INCOSE BRIEF @ DRS Technologies

  8. Customers Now: • Prioritizing Requirements: • Spiral 1, 2, 3 Evolution • Threshold Vs Objective • Key Performance Parameters Vs Key System Attributes Vs Additional Attributes • Tier Levels 1, 2, 3, 4 • Asking: • What Is Possible? • What Can Be Done Within Program Constraints and Current Technology? • What Are The Tradeoffs? Provide Me With The Best Balanced Solution! INCOSE BRIEF @ DRS Technologies

  9. RTRM Sample Sheet(Transport & Trailer Requirements) Statistics: - Number of Requirement Paragraphs: 135 - Number of Stated Requirements: 250 - Requirements Needing Clarification: 20 (8%) - Number of Requirement Disconnects: 12 (5%) Total Requirement Issues: 32 (13%) RTRM Helps To Identify & Resolve Requirement Issues INCOSE BRIEF @ DRS Technologies

  10. System N2 Diagram • The N2 diagramillustrates interfaces and relationships between system requirements, parameters, and metrics • System functions or elements are listed in the diagonal boxes • Interfaces and relationships are identified in the off-diagonal boxes. Data flows in a clockwise direction between functions or elements The next example illustrates a modified form of N2 where requirements have been listed in the diagonal boxes Helps To Surface Interface Issues N2 Helps To Identify Interface Issues INCOSE BRIEF @ DRS Technologies

  11. Example N2 Diagram

  12. Analytical Hierarchy Process (AHP) • Proven, effective means to deal with complex decision making involving multiple criteria • Captures both subjective and objective evaluation measures • A hierarchal decomposition of requirements or goals is accomplished • Pair wise comparisons of requirement attributes are made and relative scores computed for each leaf of the hierarchy • Scores are then synthesized yielding the relative weights at each leaf as well as for the overall model • A coherent assessment is reached when Inconsistency Ratio < 0.1 (http://people.revoledu.com/kardi/tutorial/AHP/Consistency.htm) AHP Helps to Determine Relative Importance INCOSE BRIEF @ DRS Technologies

  13. Requirements Model Breakdown INCOSE BRIEF @ DRS Technologies

  14. Analytical Hierarchy Process Snapshot INCOSE BRIEF @ DRS Technologies

  15. Quality Function Deployment (QFD) • There are many customers • There are stated and unstated requirements • QFD helps to prioritize requirements and their tradeoffs • QFD makes invisible requirements and strategic advantages visible • QFD helps to define which improvements provide the most gain • QFD promotes Team Consensus • QFD provides a documented audit trail for decisions The “House of Quality” Captures the Voice of the Customer INCOSE BRIEF @ DRS Technologies

  16. “House of Quality” Interrelationships between Technologies Requirements/Desires (Voice of the Customer) Technologies (Voice of the Company) Planning Matrix -Requirements Importance -Percent Improvement Desired -Marketing Competition Assessment Relationships between Requirements and Technologies Prioritized Technologies INCOSE BRIEF @ DRS Technologies

  17. Powered Trailer QFD Analysis • Two meetings were conducted with shareholders to get consensus on the Powered Trailer “House of Quality” • Body of Matrix • Common definition/scope for each requirement and technical attribute agreed to • Reinforced relationship values - by convention: • (0-none, 1-weak, 3-moderate, 9-strong) • Recognized the most important associations • Segregated positive and negative correlations, ensured they were mutually exclusive • Achieved Consensus, Consensus, Consensus • QFD was finalized via (2) additional WebEx conferences INCOSE BRIEF @ DRS Technologies

  18. Powered Trailer “House of Quality”

  19. Powered Trailer “House of Quality” INCOSE BRIEF @ DRS Technologies

  20. QFD Relative Ranking (Excludes Technical Difficulty and Cost Factors) INCOSE BRIEF @ DRS Technologies

  21. Arrow’s Impossibility Theorem(A Word of Caution!) • Combining individual preferences to form a group utility function presents a problem • The use of averaged group preference data in product design optimization can lead to erroneous results • This problem may not always be self-evident in the analysis of complex systems and products Group Consensus Must Be Reached To Avoid This Problem Provides a Hierarchical Model For Doing Tradeoffs INCOSE BRIEF @ DRS Technologies

  22. Morphological Analysis • Designed for multi-dimensional, non-quantifiable problem complexes • Explores boundary conditions • Investigates the total set of possible relationships and “configuration” alternatives • Rules out alternatives that are inconsistent or incompatible using cross-consistency assessment MA Ensures No Alternative is Overlooked INCOSE BRIEF @ DRS Technologies

  23. Morphological Field Example: 3-Parameters: color, texture, size Color: 5 discrete values: red, green, blue, yellow, brown Texture: 5 discrete values: smooth, serrated, rough, grainy, bumpy Size: 3 discrete values: large, medium, small 75 cells or configurations (Zwicky, 1969, p. 118.) INCOSE BRIEF @ DRS Technologies

  24. MA-Trailer Drive Alternatives Number of Configurations or Alternatives 4 X 6 = 24 Ruled out Combinations of Output Energy and Hybrid 3 X 2 = 06 18 Alternatives to Investigate→ (5) Drive Alternatives Remain in Trade Space INCOSE BRIEF @ DRS Technologies

  25. Powered Trailer Design Concepts • ALT #1 Electric PTO -Electrical Power Take Off provided by the transport • ALT #2 HEV -Series Hybrid Electric Vehicle with ICE, generator, and battery pack • ALT #3 HHV -Hybrid Hydraulic Vehicle with hydraulic power provided by an ICE driven power pack • ALT #4 Mechanical PTO -Mechanical Power Take Off provided by the transport • ALT #5 ICE Drive -ICE (210 HP with 340 ft-lb torque) with conventional drive train ICE = Internal Combustion Engine INCOSE BRIEF @ DRS Technologies

  26. Features Common To All Concepts • 395/85 R20 XZL tires • Central Tire Inflation System (CTIS) • Pneumatic Anti-Lock Brake System (ABS) • Serial communications with transport • Control of mobility assist and CTIS • Receipt of trailer health and cargo load status • Independent Suspension • Trailer bed basic design INCOSE BRIEF @ DRS Technologies

  27. Concepts ALT #1 Elect PTO ALT #2 HEV ALT #3 HHV ALT #4 Mech PTO ALT #5 ICE Drive Architectural Views for all Five Alternatives INCOSE BRIEF @ DRS Technologies

  28. Physical Characteristics INCOSE BRIEF @ DRS Technologies

  29. ALT #1 Elect PTO Components Detail Needed for Credible Cost & Schedule Estimates INCOSE BRIEF @ DRS Technologies

  30. Cost Vs Key Requirements Met INCOSE BRIEF @ DRS Technologies

  31. Comparison of Alternatives Weighting/Scoring 0-5 with 5 Best INCOSE BRIEF @ DRS Technologies

  32. SE Tool Usage Summary • Understanding requirements; their relationships, and relative importance: • Tools: RTRM, N2 Diagram, AHP • Getting consensus on the best technology options for meeting customer needs: • Tools: QFD (House of Quality) • Evaluating alternatives: • Tools: AHP, MA, Architectural Views • Selecting the best alternative: • Tools: Trade Study, Sensitivity Analysis INCOSE BRIEF @ DRS Technologies

  33. Conclusions • SE Process Critical for Providing Best Balanced Solution • SE Tools Assist in: • Understanding requirements and their relationships • Getting consensus on which technology options provide the greatest benefits • Assuring no viable alternative is overlooked • Performing meaningful tradeoffs and sensitivity analysis • Making decisions involving multiple attribute criteria Go to: www.incose.org for more information Capturing the Results in the Requirements Set Reduces Program Execution Risks INCOSE BRIEF @ DRS Technologies

  34. Questions ? INCOSE BRIEF @ DRS Technologies