MBSE: Documentation and Analysis
MIT xPRO | Architecture and Systems Engineering: Models and Methods of Complex Systems
Course Project Sequence | April 2026 - May 2026
The Model-Based Systems Engineering: Documentation and Analysis course focused on applying SysML-based modeling methods to document, analyze, critique, update, and manage complex systems. This course was especially valuable because it required the use of a professional SysML modeling tool, allowing the coursework to move beyond written systems analysis into actual model-based representations.
Across the course, I developed and expanded a SysML-based model of a Manned Research Submersible (MRS). The model included mission scope, system functions, requirements, structural decomposition, internal interfaces, activity behavior, safety requirements, hazard mitigations, model governance, and change-impact analysis. This course helped demonstrate how MBSE can improve traceability between requirements, system structure, behavior, interfaces, documentation, and verification planning.
Note on Project Scope
The Manned Research Submersible model was self-directed within the structure of the course. While the course provided the MBSE project framework and required diagram types, I selected the system, defined the mission scope, identified the system boundary, developed the requirements structure, modeled the system behavior and interfaces, and expanded the model across multiple weeks.
Week 1: What Is MBSE? — Manned Research Submersible Scope and Behavior
This project introduced the Manned Research Submersible as the system of interest for the MBSE effort. The work defined the system boundary, mission-level scope, major system functions, involved engineering teams, and the purpose of applying MBSE to a complex electromechanical system.
The project also developed a SysML use case diagram and activity diagram. The use case diagram represented how external entities such as the researcher/crew, research support team, and deep-water environment interact with the MRS to accomplish mission goals. The activity diagram modeled the mission flow, including crew transport, descent buoyancy control, scientific data collection, mission communication, ascent buoyancy control, and mission completion.
Concepts demonstrated:
MBSE scope definition
System boundary identification
Mission-level behavior modeling
Use case diagram development
Activity diagram development
Stakeholder and external actor identification
Function-based system understanding
Week 2: Building an MBSE Model — Requirements, Structure, and Interfaces
This project expanded the MRS model by developing model queries, a requirements diagram, a block definition diagram, and an internal block diagram. The project focused on how an MBSE model can be queried for engineering information such as function allocation, safety requirement traceability, subsystem participation, interface definition, and component distribution.
The requirements diagram organized MRS requirements into structural, safety, and operational categories. The block definition diagram decomposed the MRS into major systems such as the Structural System, Operational System, Ballast System, Propulsion and Steering System, Data Collection System, Communication System, Control System, Power System, and Life Support System. The internal block diagram focused on the Ballast System and showed interactions between the Control System, Hydraulic Pump System, Ballast Control Valve, and Variable Ballast Tanks.
Concepts demonstrated:
Model query development
Requirements diagram development
Block definition diagram development
Internal block diagram development
Requirements hierarchy
System decomposition
Interface modeling
Function-to-structure traceability
Clarity, consistency, and traceability in MBSE models
Week 3: Critiquing an MBSE Approach — Carrier-Based UAS Model Review
This project evaluated an existing MBSE approach for a carrier-based unmanned air system. The critique assessed whether the project should adopt MBSE or remain with the status quo by reviewing model scope, purpose, strengths, weaknesses, model quality, and recommendations.
The critique identified that the model was useful for early concept development because it represented major segments such as the UAS platform, carrier control station, carrier launch and recovery, mission planning, and external environmental elements. The review also identified areas for improvement, including stronger requirements traceability, verification links, alternate and failure behavior, and more detailed interface definitions.
Concepts demonstrated:
MBSE model critique
Scope and purpose evaluation
Strength and weakness analysis
Requirements-to-function traceability review
Model quality assessment
Concept-level versus implementation-level modeling
Recommendation development for MBSE adoption
Week 4: System Safety — Hazard Mitigation and Safety-Driven Model Updates
This project analyzed system safety for the Manned Research Submersible and updated the SysML model to incorporate hazards, risks, mitigations, and safety requirements. The safety analysis focused on hazards such as loss of buoyancy control, hull or pressure boundary failure, life support failure, communication loss, and propulsion or steering malfunction.
The model was updated with new safety requirements related to buoyancy control redundancy, emergency ascent, depth and pressure monitoring, life support monitoring, and emergency communication and recovery. The activity diagram was also updated to show safety-related behaviors such as verifying life support and cabin conditions, monitoring depth and buoyancy status, sending emergency status to the research support team, and activating Emergency Ascent Mode. The BDD and IBD were updated to identify blocks and interfaces involved in hazard mitigation.
Concepts demonstrated:
System safety analysis
Hazard identification
Severity and likelihood assessment
Hazard mitigation planning
Safety requirement development
Safety-driven model updates
Activity diagram modification
BDD and IBD safety traceability
Emergency ascent modeling
Verification and validation planning
Week 5: Managing the Model — Model Governance and Change-Impact Analysis
This project developed a model management plan for the Manned Research Submersible model and updated the model in response to a requirement change. The model management plan addressed model verification, input governance, communication of model results, configuration management, model ownership, funding, lifecycle change management, and model renewal planning.
The requirement change updated emergency ascent from a general backup capability to an automatic safety response. The new requirement, MRS-SAFE-002A, required the MRS to automatically activate Emergency Ascent Mode when abnormal buoyancy-control status is detected, while preserving crew override when safe.
This change was traced through the requirements diagram, activity diagram, and internal block diagram. The updated activity diagram showed monitoring depth, pressure, and buoyancy-control status, generating an automatic emergency ascent command, sending emergency status to the research support team, and activating Emergency Ascent Mode. The updated IBD showed that no new subsystem was required because the function used the existing ballast-control architecture, while still impacting the Control System, Emergency Ascent Mode, Hydraulic Pump System, Ballast Control Valve, and Variable Ballast Tanks.
Concepts demonstrated:
Model management planning
Model ownership and governance
Configuration management
Controlled model change process
Model verification and re-validation
Requirements change-impact analysis
Requirements-to-behavior traceability
Requirements-to-interface traceability
Emergency ascent architecture update
Model lifecycle planning