The problem as we formulate it is one of improper
decision making on the part of the commuter. In a congestion scenario, the commuter should avoid the 'area' that is infected
and chose alternate routes. Here the 'closest distance' algorithm should be avoided as the area which lies on the closest
distance is infected with congestion. In such a case, persistence on the closest route is meaningless and might lead to complications
in the scenario. The solution is to chose alternate routes, and the challenge in the design phase is to make that information
available to the commuter.
Sensing Techniques are reviewed for actual infection
diagnosis and Communication techniques are reviewed to understand ways of transmitting the data.
Sensing Techniques
New sensing technologies have greatly enhanced what
can be done using Intelligent Transportation Systems. Sensing systems can be either infrastructure systems or vehicle based
systems. Infrastructure sensors tend to be devices that are installed in the road or around the road, usually as part of road
construction/maintenance, while vehicle sensors are those sensors that are found installed in a vehicle. Inductive loops can
be placed in a roadbed to detect vehicles as they pass over the loop by measuring the vehicle's magnetic field. The simplest
detectors simply count the number of vehicles during a unit of that pass over the loop, while more sophisticated sensors estimate
the speed, length and weight of vehicles and the distance between them. Loops can be placed in a single lane or across multiple
lanes, and they work with very slow or stopped vehicles as well as vehicles moving at high-speed.
Traffic flow measurement using video cameras is another form of vehicle detection. Since video detection systems do not involve
installing any components directly into the road surface or roadbed, this type of system is known as a "non-intrusive" method
of traffic detection. Video from black-and-white or color cameras is fed into processors that analyze the changing characteristics of the video image as vehicles pass. The
typical output from the Image Processing System is lane-by-lane vehicle speeds, counts
and lane occupancy readings.
Vehicular Communication
Communication technologies are getting faster by the day. The Transport System can benefit greatly from the application
of information and communications technologies. Intelligent Transportation Systems vary in technologies applied, from basic
management systems such as car navigation, traffic light control systems, container management systems, variable message signs
or speed cameras to monitoring applications such as security CCTV systems.
A simple Graphical User Interface can be an effective Vehicular Communication System tool. The GUI
should be intuitive and easy-to-use such that the driver's attention should not be disrupted when using the system. A reasonable
range of communication is equally important. The system must be able to operate reliably within a reasonable range that motorists
are expected to be in for a sustained period of time.
The fast emerging Bluetooth technology can serve as
an adequate Short Range Communication System. Longer range communications have been proposed using infrastructure networks such as Global System for Mobile Communications.
Long range communications using these methods is well established, but these methods require an extensive infrastructure
beyond what is installed in a vehicle.
Fuzzy Control
The employment of Fuzzy Control is recommended for very complex processes, when there is no simple
mathematical model. It is obvious that traffic flow does not follow a uniform set of actions that can be precisely defined
by a mathematical model. The complexity of relationships in a traffic flow analysis system is not one that can be represented
analogically.
The fuzzy model consists of 4 components. The Linguistic database contains the knowledge in the form
of 'if-then' rules which is stored in a fuzzy rule base. The rules are given precise mathematical meaning through user supplied
definitions of the linguistic variables. The Fuzzifier maps the crisp values into suitable fuzzy sets.
The fuzzy inference engine interprets the fuzzy sets provided by the fuzzifier. It uses the fuzzy rule
base knowledge to produce some fuzzy sets in the output. The Defuzzifier converts the output fuzzy set to a standard signal.
Based on theoretical analysis of traffic control, generalized fuzzy rules using linguistic variables
and validation of fuzzy control principles are carried out. The input parameters we are looking at are
i.
the number of vehicles entering the street
under study (street A)
ii. the number of vehicles leaving street A
iii. Average time for a vehicle to cross the length of street A
iv. neighbourhood variable (traffic situations in preceeding areas)
The fuzzy model equation of the isolated street (street A) can be derived based on these parameters.
The basic fuction that will be constructed will apply to a simple one-way scenario. Later two way models and nodal connection
equations can be designed.
Ideally a model should generate an optimal order level. Most Optimization techniques work only for
a structured problem. Our approach to the problem at hand is to break the problem into sub-problems that are structured enough
to apply optimization. By considering Street A as an isolated problem, we aim to solve micro-problems and then work towards
a unified solution.