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1. INTRODUCTION
BlueEyes system provides technical means for monitoring and recording the operator’s basic physiological parameters. The most important parameter is saccadic activity1, which enables the system to monitor the status of the operator’s visual attention along with head acceleration, which accompanies large displacement of the visual axis (saccades larger than 15 degrees). Complex industrial environment can create a danger of exposing the operator to toxic substances, which can affect his cardiac, circulatory and pulmonary systems. Thus, on the grounds of plethysmographic signal taken from the forehead skin surface, the system computes heart beat rate and blood oxygenation.
The BlueEyes system checks above parameters against abnormal (e.g. a low level of blood oxygenation or a high pulse rate) or undesirable (e.g. a longer period of lowered visual attention) values and triggers user-defined alarms when necessary. Quite often in an emergency situation operator speak to themselves expressing their surprise or stating verbally the problem. Therefore, the operator’s voice, physiological parameters and an overall view of the operating room are recorded. This helps to reconstruct the course of operators’ work and provides data for long-term analysis.
BlueEyes consists of a mobile measuring device and a central analytical system. The mobile device is integrated with Bluetooth module providing wireless interface between sensors worn by the operator and the central unit. ID cards assigned to each of the operators and adequate user profiles on the central unit side provide necessary data personalization so different people can use a single mobile device (called hereafter DAU – Data Acquisition Unit). The overall system diagram is shown in Figure 1. The tasks of the mobile Data Acquisition Unit are to maintain Bluetooth connections, to get information from the sensor and sending it over the wireless connection,
1 Saccades are rapid eye jumps to new locations within a visual environment assigned predominantly by the conscious attention process.
to deliver the alarm messages sent from the Central System Unit to the operator and handle personalized ID cards. Central System Unit maintains the other side of the Bluetooth connection, buffers incoming sensor data, performs on-line data analysis, records the conclusions for further exploration and provides visualization interface.
The task of the mobile Data Acquisition Unit are to maintain Bluetooth connection, to get information from the sensor and sending it over the wireless connection ,to deliver the alarm messages sent from the Central System Unit to the operator and handle personalized ID cards. Central System Unit maintains the other side of the Bluetooth connection, buffers incoming sensor data, performs on-line data analysis, records the conclusion for further exploration and provides visualization interface.
1.1. PERFORMANCE REQUIREMENTS
The portable nature of the mobile unit results in a number of performance requirements. As the device is intended to run on batteries, low power consumption is the most important constraint. Moreover, it is necessary to assure proper timing while receiving and transmitting sensor signals. To make the operation comfortable the device should be lightweight and electrically safe. Finally the use of standard and inexpensive IC’s will keep the price of the device at relatively low level.
The priority of the central unit is to provide real-time buffering and incoming sensor signals and semi-real-time processing of the data, which requires speed-optimizes filtering and reasoning algorithms. Moreover, the design should assure the possibility of distributing the processing among two or more central unit nodes (e.g. to offload the database system related tasks to a dedicated server).
1.2. DESIGN METHODOLOGIES
In creating the BlueEyes system a waterfall software development model was used since it is suitable for unrepeatable and explorative projects. During the course of the development UML standard notations were used. They facilitate communication between team members, all the ideas are clearly expressed by means of various diagrams, which is a sound base for further development.
The results of the functional design phase were documented on use case diagrams. During the low-level design stage the whole systems was divided into five main modules. Each of them has an independent, well-defined functional interface providing precise description of the services offered to the other modules. All the interfaces are documented on UML class, interaction and state diagrams. At this point each of the modules can be assigned to a team member, implemented and tested in parallel. The last stage of the project is the integrated system testing.
1.3. INNOVATIVE IDEAS
The unique feature of our system relies on the possibility of monitoring the operator’s higher brain functions involved in the acquisition of the information from the visual environment. The wireless page link between the sensors worn by the operator and the supervising system offers new approach to system overall reliability and safety. This gives a possibility to design a supervising module whose role is to assure the proper quality of the system performance. The new possibilities can cover such areas as industry, transportation (by air, by road and by sea), military command centers or operating theaters (anesthesiologists).
2. IMPLEMANTATION OF BLUE EYES TECHNOLOGY
2.1. FUNCTIONAL DESIGN
During the functional design phase we used UML standard use case notation, which shows the functions the system offers to particular users. BlueEyes has three groups of users: operators, supervisors and system administrators. Operator is a person whose physiological parameters are supervised. The operator wears the DAU. The only functions offered to that user are authorization in the system and receiving alarm alerts. Such limited functionality assures the device does not disturb the work of the operator (Fig. 2).
Authorization – the function is used when the operator’s duty starts. After inserting his personal ID card into the mobile device and entering proper PIN code the device will start listening for incoming Bluetooth connections. Once the connection has been established and authorization process has succeeded (the PIN code is correct) central system starts monitoring the operator’s physiological parameters. The authorization process shall be repeated after reinserting the ID card. It is not, however, required on reestablishing Bluetooth connection.
Receiving alerts – the function supplies the operator with the information about the most important alerts regarding his or his co-workers’ condition and mobile device state (e.g. connection lost, battery low). Alarms are signaled by using a beeper, earphone providing central system sound feedback and a small alphanumeric LCD display, which shows more detailed information.
Supervisor is a person responsible for analyzing operators’ condition and performance. The supervisor receives tools for inspecting present values of the parameters (On-line browsing) as well as browsing the results of long-term analysis (Off-line browsing).