The operating environment of a Tactical Command and Control system is a highly tense one in which the operator needs to perform certain complex tasks with minimum confusion, and be able to obtain an instant response from the system. Since many of the systems designed for these types of environment are similar in nature with regard to the user-interface, a need has arisen to try and standardise certain elements of the systems.
This report looks specifically at standardising certain graphical display element and operator input device interfaces. It investigates the problem from a systems design level, identifying the elements required and their associated functions, discussing the results of work already undertaken in the field, and making recommendations on the use of the elements.
The main objective to standardising the Man-Machine Interface (MMI) design element is to make the code easily transferable between different hardware platforms. To transfer the code, one would ideally like to change only the interface code to the new platform, in particular, the interface to a different set of operator input devices and a different type of graphics card.
Various topics related to the standardisation process are discussed, including a description of MMI design, some definitions of tactical command and control environment subjects, and a look at code reusability, rapid prototyping of systems, and object-oriented design.
The first major requirement of the standardisation process is the design of the graphical MMI display elements that are identified as being common to the various systems. This design includes the definition of co-ordinate systems, and an investigation of the use of colour to encode different meanings for groups or types of display elements, and the colours used for the different system modes of operation. The graphical MMI elements identified as being common to the various systems under investigation include: soft-buttons, totes, message bars, Plan Position Indicators (PPIs) and information boxes.
The second major requirement of the standardisation process is the identification of the operator input devices and the design of their interfaces. The input devices identified as being common to the various systems under investigation include: a keyboard, softkeys, a joystick, and a touchpanel. Related to the design of the input device interfaces, is the design of input device event queues that handle all the inputs from the various devices, and convert these inputs into system events that can be handled by the system state-machine. Configuration files are used to enable the code to run on various hardware platforms that have either different types of input devices, or a different method of interfacing to the devices. Various hardware configurations and interfaces have been used to date. One of these configurations is a PC prototyping environment with a mouse and an IBM keyboard as input devices, using a PC serial port and the keyboard input. Another is a Multibus II (MBII) environment with an alpha-numeric STORM keyboard, STORM keypad softkeys, a joystick and a touchpanel as input devices, using serial input ports and MBII message passing.
The system operation as a whole is based on a scheduler, input device interrupts, and state-machines. The two main system state-machines are the logic-and-control state-machine, which interfaces with the system sensors, and the user-interface state-machine, which is discussed in this report. The user-interface state-machine uses displayed menus as the state-machine states, and decodes operator inputs into events for the state-machine, each of which has its own action function.
To illustrate the success of the standardisation design process, examples are given of systems already designed, and of work in progress. Photographs are used to illustrate the display screens and operator input devices used, and to give an indication of screen layouts and colour codings used.
From system design work already undertaken, the transportability of the software between different hardware platforms and system configurations has been successfully performed a number of times. This has made possible the use of low-cost PC-platform prototyping to speed up the design process, and has allowed frequent meetings with the users to obtain their comments during this design process. Recommendations arising from this work include the investigation of using other programming languages and packages that may speed up the design process even further. It is also recommended that the system designed be observed under actual operating conditions.