PC-BASED COMMUNICATION BOARD SIMULATOR FOR TEACHING

Dominic P.K. Cheng Rehabilitation Engineering Centre The Hong Kong Polytechnic University

ABSTRACT

The aim of this project is to provide a PC-based communication board simulator for teaching in a university course on assistive technology with a class size of twenty students. The simulator allows a student to explore different communication board configurations with or without digitized voice or sound output, and different phrase/sentence retrieval strategies. The hardware and software requirements of a PC required to develop the simulator and that to run the simulator are described. Using communication board simulators for teaching is cost effective in view of the number/variety required and the high cost of commercial products. This approach is also flexible because the behavior and functions of a PC-based simulator can be readily changed and expanded when the need arises.

BACKGROUND

Using simulators for training is not new. Well known examples are those used for training pilots and astronauts. In industrial applications, simulation is a cost effective way to offer training in a safe and controlled environment. In business and military applications, simulators in the form of games provide immediate feedback to actions taken under different scenarios.

The use of simulators for teaching is relatively new. With the availability of low cost personal computers, software simulators have gained popularity especially in the teaching of technical subjects where the actual construction of circuits and devices or the use of real objects are too time consuming and expensive. An outstanding example is the ubiquitous PSPICE, an electronic circuits simulator, used in all courses dealing with electronic circuits.

STATEMENT OF THE PROBLEM

In the teaching of assistive technology, assistive devices for the disabled is of particular interest to paramedics and engineers. Assistive devices are generally expensive because of the large variety required to satisfy different needs and the relatively small volume for a particular type of device.

Electronic aids for communication are particularly fast changing, tailing closely the development of electronics and computing. Acquiring state-of-art devices in sufficient numbers for teaching is unrealistic. Considering cost alone, a portable device with speech output costs from a few hundred US dollars to several thousand dollars. At present, there is no simulator of communication aids for the disabled available.

RATIONALE

In general, an electronic communication board is a portable device which has a number of positions. Each position has an associated light and a tag on which a picture, phrase or symbol can be attached. The lights will advance in a prescribed scheme and the user communicates by selecting one or more positions. A position is selected when the user activates the ability switch when the light reaches the desired position.

As previously described, an electronic communication board is essentially an event-driven graphical interface for a disabled user. In other words, an internal event by a built-in timer controls scanning of the symbols, and an external event in the activation of an ability switch by the user selects a symbol. The Windows platform is well suited for graphical applications. Visual Basic, an event-driven programming language specifically designed to develop Windows applications, is most suitable for the development of PC-based communication board simulators.

For teaching purposes in a laboratory setting, portability is not an issue and a desktop PC with a sound card can be used to simulate an electronic communication board with speech output. The monitor screen can display the panel of a communication board and the sound card can provide excellent speech output. The hard-disk that comes with a desk-top PC has a large storage capacity which is well suited for storing audio files as well as `storage-hungry' image files.

In terms of cost, PCs are already available for general teaching. The cost of adding a sound card and speakers to a PC is very low compared with the cost of even a low priced commercial communication board.

IMPLEMENTATION

Fig. 1 shows the Development System and a Teaching Station. The Development System consists of a 486DX2-66 PC with a CD-ROM drive, a sound card and a video card. A Teaching Station needs only a 386SX or better PC with only a sound card.

The sound card serves as the audio interface for audio input/output. Audio input can be recorded live using a microphone or from pre-recorded sources such as a CD player or cassette tape recorder. The sound card has built-in output audio amplifiers to drive a pair of small loudspeakers. The video card serves as the video input interface for sources such as a video camera. The rich sources of digitised AV material such as clip-arts and sound files can be inputted using the CD-ROM drive. Printed images can be captured using a desktop scanner.

The Development system requires Windows and Visual Basic for developing the simulator software. Visual Basic does allow compilation of an application into a true .EXE file that can be run under Windows with only a run-time DLL. In order words, there is no need to install and paid for a license of Visual Basic in a teaching station.

Fig. 2 shows the Communication Board Emulator `options' screen. It allows the student to choose communication board matrix sizes from 2 x 1 to 4 x 8. Common scanning techniques using various ability switch configurations can be accommodated. Symbols can be stored in 3 different pages to increase the number of symbols in a given matrix size or to allow organization of the symbols for different situations, such as those in the home or school environment.

Fig. 3 shows a possible arrangement of a 1 x 2 board with the symbols for 'Yes' and 'No'. A voice message for each symbol can be recorded if desired. Fig. 3 shows one possible page of a 2 x 5 communication board. The student can choose up to three symbols and record a message corresponding to this particular symbol sequence if audio output is desired. Using a symbol combination to identify a given message enables selection of a large number of messages using a limited number of available symbols. For example, the three chosen pictures in Fig. 3 can be used to retrieve the message "I like cats and I like to drink hot tea.".

DISCUSSION AND DEVELOPMENT

The Communication Board Simulator as described is designed for teaching purposes. The student will have a chance to explore different message retrieval strategies and gain hands-on experience on their limitations and how that affect communication efficiency. In this regard, the limitation on the matrix size and the lack of other useful message retrieval strategies, such as `picture-stringing' is not a major problem.

One shortcoming in this present implementation is that only the cursor keys are used to simulate real ability switches. One very simple way is to provide a 'break-out' box for the cursor keys of the standard keyboard which only requires minor technical work. A more elegant way is to use the games port for switch input. In this case software code has to be added to drive the games port and some hardware interface has to be provided between the ability switches and the games port. In either technique, the real limitation is the budget required to purchase the ability switches.

Since the simulator is software based, the user graphics interface in terms of matrix size and functions such as picture- stringing can be implemented without any change of hardware. Under the Windows environment, a retrieved message can be a full-motion video - a function that is uncommon even in expensive commercial products.

The simulator will be used this coming term in a course on assistive technology. The course has a class size of twenty students mainly of paramedics. The simulator will be used in laboratory sessions and possibly provided to students for home assignments. The simulator will be modified according to student feedback and developments in the commercial sector.

ACKNOWLEDGEMENT

The hardware/software expertise of Mr. Siu Sik Cheung is much appreciated.

Dominc P.K. Cheng REC, The Hong Kong Polytechnic University Hung Hom, Kln. Hong Kong email rcdpkc@polyu.edu.hk