Task Analysis: A Model Based Human Systems Engineering Approach

Model-Based Systems Engineering (MBSE) is the formalized application of modeling to support system requirements, design, analysis, verification, and validation activities beginning in the conceptual design phase and continuing throughout development and later life cycle phases. Human Systems Engineering (HSE) consists of human factors engineering, safety, training, survivability and force protection, habitability, manpower, personnel, training, and human-centered engineering. Model-Based Human Systems Engineering (MBHSE) is the intersection of the two disciplines. MBHSE aims to address the deficiencies of MBSE in adequately including humans within system and analytical models. A key pillar of effective Human Systems Engineering is the Critical Task Analysis. A Critical Task Analysis (CTA) is a systematic process used to identify, analyze, and evaluate critical tasks within a system or process. These are tasks that, if not performed correctly, can have significant negative consequences such as accidents, injuries, system failures, or financial losses. One comprehensive CTA approach is through a Mission Task Analysis (MTA). An MTA systematically analyzes how operators interact with the system within the context of specific mission goals and operational environments. MTA is a method of task analysis designed to cover all aspects of the mission under all expected operating and environmental conditions. Conceptually, MTA operates on three levels. At the mission level, the goal is to identify system requirements that map to human performance requirements. At the function level, the method allocates functions and identifies machine-related requirements that translate into human performance requirements. At the task level, the method identifies specific behaviors, information flows and needs, interaction dynamics, decision parameters, safety assessments, workload dynamics (visual, auditory, cognitive, and psychomotor), automation considerations, and other key human factors elements.Current MBSE methods, practices, standards, and procedures omit key elements of how operators interact with systems-of-interest. This paper describes a novel approach to effectively model system operators and users. The MBHSE task analysis outlined in this paper uses SysML to conduct and capture a Mission Task Analysis in support of system design and improvement. The approach focuses on both compiling existing MBSE architecture models and generating new models that provide more information about critical tasks. Existing views that support a task analysis include the Department of Defense Architecture Framework (DODAF) Operational Activity to Systems Function Traceability Matrix (System View 5a; SV-5a), Operational Activity to Systems Traceability Matrix (System View 5b; SV-5b), Operational Activity Decomposition Tree (Operational View 5a; OV-5a), and Operational Activity Model (Operational View 5b; OV-5b). Relying solely on these existing views does not allow human systems engineers to fully conduct, represent, or communicate the requisite components of a Critical Task Analysis.To augment standard MBSE approaches, MBHSE generates additional models. These include models that show task-relevant information exchanges within the system architecture; models that capture all variations of the sub-tasks steps and sequences; models that capture the key input and output parameters for decisions related to the critical tasks; models that provide design recommendations for various levels of automation relating to a task; and models that capture the critical knowledge, skills, and attributes (KSAs) operators must possess to execute a task.