6. The PROMISE multimedia interface project

The overall objectives of the PROMISE project (PRocess Operators Multimedia Intelligent Support Environment) are twofold:

(1) the design' construction, and evaluation of a multimedia tool set for improving user interfaces to advisory and diagnostic expert systems used by single operators in process control environments;
(2) the development of a methodology to support designers using the tool set.

6.1 The Media Supported

The PROMISE system is multimedia, as it supports many ways of communicating information, and multimodal, as many styles of interaction are supported. The system supports a number of multimedia options [2], including:

- text, graphics, and sound output
- full colour
- live and still video output
- text and Mouse input
- two-dimensional animation
- unmediated video
- natural language output (speech)

The media "unmediated video" [1] perhaps require some explanation. The term subsumes many others, including algorithm animation, data fusion, visual realization, program visualization, and abstract representation. It is best illustrated by an unmediated audio example. In the 1960s, ICL engineers linked the data bus of a 1900 series computer to a loudspeaker, no doubt for hardware debugging purposes. The loudspeaker was left in the operator console of the computer and could be heard by increasing the volume control. It is almost certain that this information was never intended for operator use, but it soon became an extremely useful operator aid. Although the connection between the sounds emitted and the machine activity was never explained, operators were rapidly able to use the information to tell if the machine was idle, which job was running, and if a job was in a loop. At night, this use of the auditory channel also enabled such monitoring to take place in the operator tearoom adjacent to the computer room, probably the first recorded example of a multimedia interface advantage. There are other, more visual examples of this approach that have been used in process control.

6.2 The Environments

The multimedia approach in PROMISE is being applied in two distinct types of environment that will help us in evaluation - a real-time application and a simulated one. The real environment puts serious constraints on the evaluation environment, since the clock cannot be stopped and unanticipated events can occur. Such an environment also poses other problems from an evaluation standpoint. Errors cannot be deliberately introduced or reproduced, and controlled experiments are difficult. Therefore a simulated environment where we can control the nature of the upsets and monitor operator performance will also be used. The two application areas chosen are control of a chemical plant (DOW Benelux) and the use of power station simulators (Scottish Power).

6.3 The Unique Features of Multimedia Usage in Process Control

Most multimedia ideas grew out of work in computer education. The educational multimedia approach involves the use of videocomputers, interactive television, and electronic books to provide a richer educational environment. It is envisaged that a user will be able "to browse through vast libraries of text, audio and visual information" [4]. These libraries will be highly interlinked using a technique known as "Hypermedia," a concept developed from Hypertext that was first defined in the 1960s and led to the Xanadu system [18]. Most of the current literature about multimedia approaches derives from the educational sector. These educational applications tend to be activated by the learner alone where the user of the multimedia system is in complete control.

In contrast, the process control environment places extremely demanding requirements on the architecture of a multimedia presentation system.

- The operator may be engaged in many distinct tasks simultaneously, for example monitoring, tracking alarms, etc.
- New tasks and hence interactions may be instigated at any time by either system or operator.
- The process state may be extremely dynamic, so information may need to be presented rapidly and in a form that is readily understood by the operator.

The designer of a user interface cannot know in advance what combinations of multimedia resources might be required. The problem may therefore be thought of as a resource management problem, managing the competing requirements of different media for the limited resources of the interface. The existence of additional media provides problems and opportunities. The problems are those of "media-clash" - for example, several alarms wish to use the audio channel at the same time. The opportunities come from the ability to switch media to overcome the problem.

6.4 The Architecture

The overall architecture is shown in figure 3.

The actual realization of an object is derived from:

- designer options: the designers specify alternative renderings of an object and provide measures of their preferences for such rendering;
- resource limits: the availability of the physical rendering resources;
- multimedia options: given a choice, what would be the preferred rendering?
- operator preferences: are there special operator requirements (i.e. colour blindness)?

At the far right are the dynamic system to be controlled and the "supervisory and control system" that controls it. The PROMISE system is an advisory system so that the operator can completely ignore it if required and can control the process separately. Indeed, no direct control of the system is possible through the PROMISE terminal. An "advisory/diagnostic knowledge based system" is shown in the figure, though such a system is not actually part of PROMISE. At the heart of the tool set is the "interactive data model." This module models the relevant portions of the plant and all objects rendered to the operator. It is therefore a key player in consistency maintenance. The "presentation server" actually renders the images, sounds, etc., under control of the "resource manager," which decides what media will be employed taking into account the designers' preferences, the current resource usage, the user preferences, and general rules about rendering (the M41 Knowledge in the diagram).

Figure 3

Currently, this tool set is being installed in the chemical plant and in a nuclear power station simulator so that experiments can be carried out on the effectiveness of multimedia interfaces. In parallel, a series of experiments are being carried out in the behaviour laboratory at Loughborough University.