Traffic lights control system
Design criteria and constraints
Fuzzy logic traffic lights controller system
Input and output membership functions
Fuzzy rule base
Inference engine and defuzzification
Traffic congestion is a severe problem in many modern cities around the world. Traffic congestion has been causing many critical problems and challenges in the major and most populated cities. Due to these congestion problems, people lose time, miss opportunities, and get frustrated.
In this report we discuss the implementation of an intelligent traffic lights control system using fuzzy logic technology which has the capability of mimicking human intelligence for controlling traffic lights. A software based on Visual Basic has been developed to simulate an isolated traffic junction. Fuzzy logic technology allows the implementation of real-life rules similar to the way humans would think. For example, humans would think in the following way to control traffic situation at a certain junction: “if the traffic is heavier on the north or south lanes and the traffic on the west or east lanes is less, then the traffic lights should stay green longer for the north and south lanes”. Such rules can now be easily accommodated in the fuzzy logic controller. A comparison between the performance of the fuzzy traffic lights controller and the conventional fixed-time controller is attempted and discussed in the section that follows. TRAFFIC LIGHTS CONTROL SYSTEM
Basically, there are two types of conventional traffic lights control system that are in use. One type of control uses a preset cycle time to change the lights. The other type of control combines preset cycle time with proximity sensors which can activate a change in the cycle time or the lights. In the case of a less traveled street which may not need a regular cycle of green lights, proximity sensors will activate a change in the light when cars are present. This type of control depends on having some prior knowledge of traffic flow patterns at the intersection so that signal cycle times and placement of proximity sensors may be customized for the intersection.
Fuzzy logic traffic lights control is an alternative to conventional traffic lights control which can be used for a wider array of traffic patterns at an intersection. A fuzzy logic controlled traffic light uses sensors that counts cars instead of proximity sensors which only indicate the presence of cars. This provides the controller with traffic densities in the lanes and allows a better assessment of changing traffic patterns. As the traffic distributions fluctuate, the fuzzy controller can change the signal light accordingly.
The general structure of a fuzzy traffic light control is shown in Fig.1. It has two electromagnetic sensors placed on the road for each lane. The first sensor behind each traffic light counts the number of cars passing the traffic light, and the second sensor which is located behind the first sensor counts the number of cars coming to the intersection at distance D from the lights. The number of cars between the traffic lights is determined by the difference of the reading between the two sensors. This is in contrast to conventional control systems which place a proximity sensor at the front of each traffic light and can only sense the presence...