Buz Net

The development of the BusNet system is looking to provide a way for constant road condition monitoring.

SrilankaroadA good road system provides many benefits - vehicles consume less fuel on well maintained road surfaces, smooth movement of traffic cuts travel time, and the reduced traffic congestion reduces environmental pollution. In countries like Sri Lanka, the lack of funds is a factor, as well as the lack of monitoring and reporting systems. The BusNet system is looking to addresses these two issues. It provides the ability to trigger the maintenance system into action before the road conditions deteriorate beyond the safe and acceptable level which reduces the cost of repairs.

Continuous monitoring of a road network's surface condition requires a vast monitoring solution. In Sri Lanka, it is impractical to deploy a large number of sensors; however researchers have found a way to use the current public transportation system to gather data. The buses in the public transport system travel the roads frequently and are able to gather the required data. By utilizing the public transportation system, the researchers at University of Colombo, have an establishedBusnetarchitecture infrastructure that allows them to use fewer sensors on the vehicles but gather data from different locations as the buses all have central points from which the regional networks span out. Although sensor boards and motes are relatively inexpensive, the cost is still to high for developing countries. These vehicle mounted moving sensors gather data that covers a large geographical area. When the buses arrive at the bus stations, which also function as data collection centers, the gathered data is transferred through the wireless sensor network to the base station. The data collected is used to study and determine long term changes.



The BusNet system consists of three main components: Sensor Units, Sub Stations and a Main Station. BusNet uses Crossbow's MICAz Mote and a variety of sensor boards. The sensors gather the required data along the bus route which is stored with the GPS coordinates of the collection points. Once the bus reaches a sub station, the data is relayed over the wireless sensor network to the sub station which routes the data back to the main station over the bus system's network. The substations act as routers gathering the data and sending it to the main base station. By using the public transportation infrastructure, BusNet allows for cost reduction as not as many sensor nodes are required, and it is easy to provide maintenance on the nodes (changing batteries, etc.) as the buses return to the station every day.

Busnetdata_2The accelerometer on the sensor board is capable of measuring both vertical and horizontal acceleration. Researchers have conjectured that the normal component of the acceleration has a correlation with the road surface condition. For example, if the bus goes over a pot hole this would cause a significant change in the normal component of the acceleration. The collected readings are transmitted over the BusNet to the central collection point at the Main Station and maintenance can be dispatched if necessary. To make this data useful, researchers at the University of Colombo's School of Computing have collaborated with the Department of Physics to factor out attributes such as the suspension system, weight of the vehicle, size of the tires, etc. that may have an impact on the acceleration readings and have created an analytical model to estimate road surface conditions. The plan is to create a neural network to estimate the roughness of the road surface based on the acceleration data. The sensor units on the BusNet are given a threshold value of acceleration that indicates significant deterioration of the road surface so that the data collection can be triggered by that value as the sensor unit has memory constraints and such a triggering point conserves storage space.

This system is still in development, however, the concept is innovative. BusNet is a novel approach in building a vehicle based data network. It is a viable solution for sensor network applications that are delay tolerant and are used for predictive and preventive maintenance. It sets up a communication infrastructure, enables additional monitoring solutions and provides a solution to observe a vast area with fewer devices. The road surface monitoring system it hopes to offer will enable developing countries like Sri Lanka to create a better road network infrastructure and sustain it

Wireless Sensor Networks

A wireless sensor network (WSN) is a wireless network consisting of spatially distributed autonomous devices using sensors to cooperatively monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants, at different locations.[1][2] The development of wireless sensor networks was originally motivated by military applications such as battlefield surveillance. However, wireless sensor networks are now used in many civilian application areas, including environment and habitat monitoring, healthcare applications, home automation, and traffic control.[1][3]

In addition to one or more sensors, each node in a sensor network is typically equipped with a radio transceiver or other wireless communications device, a small microcontroller, and an energy source, usually a battery. The size of a single sensor node can vary from shoebox-sized nodes down to devices the size of grain of dust.[1] The cost of sensor nodes is similarly variable, ranging from hundreds of dollars to a few cents, depending on the size of the sensor network and the complexity required of individual sensor nodes.[1] Size and cost constraints on sensor nodes result in corresponding constraints on resources such as energy, memory, computational speed and bandwidth.[1]