A COMPUTER BASED TRAINING SYSTEM FOR THE TGV RADIO-SECURITY PROCEDURES F. Gavignet, F. Andry Cap Gemini Innovation Boulogne-Billancourt, France
[email protected]
Abstract In this paper, we describe a computer based training system developed for the French National Railways (SNCF). This system is used to teach the French drivers the functionalities of the new radio control unit they will be able to use on either the French, British or Belgium rail networks and to train them to the new radio procedures that they will execute in English. The system combines multimedia techniques like video images restitution or speech recognition, for simulation quality purpose. After a description of the functionalities and architecture of the system, we present the user interface and the way speech technologies have been used.
Key-Words : human security applications, user-system interaction, CBT, speech recognition, multimedia.
1.
Introduction
With the development of the high speed railway network throughout Europe, the radio security system on board of the TGV (bullet train) must be compatible with the different procedures from one country to another one. For this, the French National Railways (SNCF), in cooperation with foreign railway companies, have designed a new radio control unit. For language independency purposes, the unit contains mainly icons buttons. Besides this, since procedures dialogs are very often conducted in foreign languages, the dialogs have been modified and constrained like aeronautic radio procedures. This avoids misunderstandings and ensures optimal security of the communications. In order to guarantee that drivers will be operational when the TGV traffic will start between Paris and London, the SNCF needs a system to teach its drivers how to use the new radio unit and the associated procedures. As SNCF was concerned with the cost of such a complex training program, we suggested to use speech technology to partially encode the linguistic expertise. We proposed to integrate speech recognition in a multimedia computer based training system to allow both discovery of the new radio functionalities and training to the new procedures.
2. Overview of the functionalities The pedagogic content of this application is shared among two modules: the discovery of the functionalities of the new radio control unit, and the training on the new radio procedures. The first module consists of using the keys of the control unit to learn the function of each key, and then to run a fixed number of random evaluations based on case simulation. The behavior of the training simulator takes into account all the parameters of a real journey according to a specific network (local procedures, radio channels, train identifications...). The second module gives the user the possibility to run a simulation for a specific situation, including security problems, that requires phone calls in foreign language.
3.
System Architecture
The application incorporates a compiler that translates the scenarii and dialogues descriptions from a textual form to a format that is interpretable by the system. Such a tool allows further modifications of the simulation, given that the behavior of the radio control unit was supposed to change.
fig. 1: system architecture
When running, the kernel of the system interprets the compiled modules to execute the lessons and the dialogues. A history file is written for further examination of the progress of the trainee, and that will contribute to the study of the feed-back information phase on the system. (...)
4. The user interface Since the trainees are TGV drivers that are not very accustomed to computer use, the external aspect of the system is limited to a touch-screen, a couple of loud speakers and a radio telephone receiver connected to the system. The loud speakers provide restitution of different sounds (buttons use, simulated alarms, etc), depending on the context. The touch-screen enables user's inputs like manipulation of the radio control unit and of course output of the display.
fig. 1: overview of the system
fig. 2: radio unit simulation screen.
The telephone receiver is a copy of the original one that is on board in the TGV cabs. It allows realistic simulations of the dialogues by reproducing pre-digitized speech files of the incoming sentences of the traffic controller. The receiver is also used for trainee's sentences acquisition. This includes: checking of picking up, hanging up and coordination of the transmission (the radio protocol is uni-directional like in walkie-talkie communications). The system is installed on a PC platform. It is equipped with a CD-ROM player (for pictures, videos and large recognition data storage) and an INTEL DVI board for video restitution. The applications runs under Windows 3.1.
5.
The use of Speech Technology
The needs, for the speech recognition component, were the followings: having continuous speech recognition capabilities with local scores delivery, on part of the users sentence, instead of getting an absolute score for the whole utterance. The aim is to be able to check words of phrases pronounciation, with regard to their security weight in the sentence. For qualifying the pronounciation, it has been originally intended to use three different recognition database: English natives, French fluent in English, French persons who start speaking English. The latter has been finally splited into three new levels of pronunciation: -1- the dialogue will not be affected, but a progress is expected, -2- the dialogue might suffer and some improvement is required, -3- strong mistakes will lead to the failure of the dialogue. When invoked, a screen shows the scores of all the sentence items to the user (the example in fig. 3 is for the sentence "Ashford signals, this is train 9004 standing at signal AD99, over."). The utterance segments differ in their colors and heights, according to the pronunciation level.
fig. 3: evaluation screen The recognition component consists of the RS1000 board and software from VECSYS, based on the LIMSI technology [1]. Recognition reference databases have been computed on a panel of about one hundred speakers, shared among the five levels of pronounciation described above. The speakers were selected by an office of the Education Nationale (CITE LANGUES), in charge of the linguistic aspects. A specific release of the software has been realized to allow up to 25 seconds of speech acquisition. This gives the trainees the possibility to incorporate silences in their utterances, like in real situation.
6.
Conclusion
In this computer based training system, we combine a graphic simulation of the security control unit with innovative speech technologies. The advantage of this system is not only to train the drivers in conditions very close to real situations, but also to test and validate the human factors when facing an emergency on the TGV. This includes the combined use of the procedures book and annotations in the driver's log of all the security informations (signals, authorizations, dates and times). The system is already used in the French Eurostar training center in Lille since April 1994.
Acknowledgments We would like to thank VECSYS that proceeded to the speech references computation and supplied both the recognition board and the telephone receiver. We also thank Cité Langues, that collected the speech samples.
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