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6.6 Human Computer Interface

Many pressures on satellite operators can be alleviated by using standardized, user-friendly, human-machine interfaces. There are several military standards addressing the HCI in ground system environments. Many standards, however, have become outmoded since X-Windows/Motif became the prevailing industry standard for HCI. In testbed environments, satellite operator preferences have been identified and evaluated for effectiveness in the context of both military and commercial standards. Recommendations are made available to satellite programs to assist in selecting effective operator displays.

The HCI can improve the effectiveness of the satellite operator in several ways. The operator screen can be divided into zones providing system status, alerts and alarms, a main menu, and a work zone. Standard screen real estate, colors, diagrams, and screen navigation aids also greatly increase an operator's effectiveness. This standardized interface also promotes interoperability between satellite programs and reduces operator training time.

Many operator screens can be reused from one satellite program to another. Many satellites have similar attitude control subsystems, thermal subsystems, and electrical power subsystems. Operator screen prototypes for these subsystems that can be used by several different satellite programs have wide acceptance in the satellite control community. Screens of this type will allow operators familiar with one system to transition to another without extensive training.

Testbed environments at Aerospace have been used for exploration, evaluation, and definition of standards for military and commercial satellite control environments. These efforts have indicated that it is possibility to standardize formats or generic templates among different satellite programs. Prototypes using COTS Graphical User Interface (GUI) builders are hosted on high-end workstations to identify a combination of methods, specifications, formats, and templates for easing the transition from single satellite control environments to multisatellite control environments.

Ideally, the HCI becomes a partner with expert systems for operator support. The HCI displays results of the expert system by showing satellite and ground equipment status messages and recommendations in a scrollable window. It can also highlight those components where an anomaly has been detected.

The HCI is constructed with either a low-level programming language or with any of several GUI builders. Tools that generate code generally provide more flexibility and more options for screen design and functionality. The drawback is that the developed code will have to be maintained, thus increasing maintenance costs. "Shrink-wrapped" GUI builders provide slightly less functionality, but shield the developer from the code maintenance problem.

A variety of HCI development products are available today. These products include development libraries like X/Motif, code generating products such as Teleuse from the Telesoft Corporation and X/Designer, and shrink-wrapped packages such as Dataviews from VI corporation and Sammi from Kinesix. These products are being applied in a variety of TT&C applications by Aerospace and various defense contractors.