THAAD User Interface Design

Program Manager, July-August, 2001 by Maj. Dan Wiley, Dr. Chris B. Grounds

Relying on Adherence to Standards, Soldier Involvement

Developing a user interface for any system presents challenges; most notably, an interface must be usable by soldiers across a broad spectrum of experience levels and performance differences. These challenges can be addressed by adhering to the Department of Defense (DoD)-mandated Human-Computer Interface (HCI) standards and involving the user frequently during the interface design process.

The Operator System Interface (OSI) Integrated Product Team (IPT) is one of several LPTs on the Theater High Altitude Area Defense (THAAD) Project. This team has been developing a User Interface that maximizes functional capability while ensuring soldier performance and accuracy by using a tried and true screen design process. Although much work remains to be done, the process is sound and results to date have been extraordinary. A key aspect of the THAAD process is the involvement of soldiers in the design. This article provides a brief overview as well as benefits to the THAAD program from using this process.

THAAD Background

On June 23, 2000, Dr. Jacques Gansler, former Under Secretary of Defense for Acquisition, Technology and Logistics, formally approved THAAD's entry into the Engineering, Manufacturing, and Development (EMD) phase. The THAAD mission is to protect multiple, widely dispersed assets from short-to-medium- range Tactical Ballistic Missiles. The THAAD system consists of five segments: Battle Management Command, Control and Communications (BM/C3I; Launcher; Radar; Missile Round; and Peculiar Support Equipment. The BM/C3I Segment acts as the integrator to coordinate the segments into a weapon system.

BM/C3I software development occurs within six functional areas: Operations Management, Battle Management, Communications Management, System Support, Embedded Training, and OSI. The OSI acts as the conduit between the command and control operator and the BM/C3I system.

User Interface Design Guidance

Scientifically validated guidance acts as the first input into the design process. This guidance comes in the form of performance and usability-based standards such as MIL-STD-1472, Institute of Electrical & Electronics Engineers Standards on Graphic User Interface Design, Open Software Foundation Motif Style Guides, and Apple/Microsoft standards.

Principal documents governing user interface design include:

* Department of Defense Joint Technical Architecture (April 2001)

* Joint Technical Architecture -- Army (May, 2000)

* Department of Defense Technical Architecture Framework for Information Management (TAFIN), Volume 8, "DoD Human-Computer Interface (HCI) Style Guide" (June 1994)

* Defense Information Infrastrcture (DII) Common Operating Environment User Interface Specifications (October 1999) U.S. Army Weapon Systems Human-Computer Interface (WSHCI) Style Guide (December 1999).

The TAFIM guides the lowest levels of interaction; it provides guidance for color usage, font sizes, and principles of organizing information within the user interface. The DII User Interface Specification provides guidance for ensuring consistent use of screen "widgets" such as push buttons, pulldown menus, and text fields. Finally, the WSHCI Style Guide provides guidance for developing the interface for real-time situations such as the battlefield. It includes recommendations on what types of information to display at all times or how to ensure the soldier has access to information at critical points in a battle.

Human-Centered Design

A unique aspect and possibly the most important input into the design process for BM/C3I OSI development has been the focus on human-centered design. Early involvement of the soldier in the development effort has proved to be a quick and effective way to incorporate direct feedback into the design. Figure 1 outlines the typical design process of new screens or modification of existing screens.

Step 1 involves identification of problem areas in the OSI by representatives from the THAAD Program Office, the soldiers, or the contractors. Problems may exist with prior screens, or there may be concerns about how a particular future function will be displayed to the user. Issues can often be resolved without experimentation by incorporating human factors design, previous experimental results, and screen templates. If issues cannot be resolved or more than one solution is offered, then screen experimentation is necessary.

Step 2 involves design of candidate screens to resolve the screen issues identified in Step 1. First, the designer should conduct a task analysis of the screen. Identifying the purpose of the human interacting with the particular screen or set of screens is important to the task analysis effort. Cognitive task analysis tools such as Goals, Operators, Methods, and Selection Rules are useful for breaking the overall purpose of each task into sub-tasks and screen interaction methods that can support those sub-tasks. Once the tasks and sub-tasks are defined, screen interaction methods are proposed. Designs are constrained, however, to keeping candidate screens consistent with the rest of interface. Simply designing each window with good human factors' input without designing for consistency will defeat the benefit intended by the human factors' design.