Traffic light control system

Fahimeh Hosseini, Nazanin Yazdian
supervised by Professor Vadim Geurkov

In this work, a smart traffic light system is proposed. In addition to the common functionality of the conventional traffic lights, the newly designed system incorporates additional features to assist visually impaired pedestrians safely cross the street. Moreover, in the case where a vehicle runs a red light or passes the speed limit, the picture of the offender's vehicle is acquired. The obtained image is then sent to a computer and automatically processed to extract the driver's information.

A microcontroller is dedicated to take care of the calculations, timings and assigning priorities to the tasks to be performed. The presence of the pedestrian at the intersection is input through a push button pressed by them. Depending on the current light status, it is determined when they can cross. A sound is produced to inform the pedestrian that it is safe to cross. Sensors are allocated on the sides of street to detect weather a vehicle has crossed the stopping line and a warning alarm is activated for the crossing person's safety. The other main feature of our system is its capability to automatically recognize and reveal the information of a lawbreaker individual to the regulators. A camera is mounted such that at two different events, it captures the image of the offender vehicle. The mentioned events that trigger the camera are: 1. the vehicle crosses the red light 2. The vehicle is driving faster than the speed limit. The taken picture is sent to a remote computer for further process. The plate number is extracted and then an automatic character-detecting algorithm is run on the plate number. This result is provided to the officials for the legal procedures.

PIC32MX7 microcontroller which is mounted on a development board called CEREBOT MX7ck is chosen for this project due to its multiple timers, priorities, high memory capacity, numerous input/out pins and its low cost. The system is controlled by a remote PC using RS-232 for communication between the PC and the microcontroller, using asynchronous serial communication interfaces (UART).

The rationale behind how the traffic signal switching lights is a finite state machine that contains three main states which are Green, Yellow and Red states. During the Red-state if a car passes through intersection, microcontroller will detect the event as an interrupt (Change Notification) and will trigger the camera to take a picture of the offender car. The microcontroller also monitors the speed of the cars at all the time and again an interrupt (Change Notification) will be generated if the speed of any car exceeds the limit. At all times the speed of running cars is calculated and stored in the system. If the speed exceeds limits the inexpensive CMOS camera takes the photograph of offender's plate and stores it in the memory. Then the plate number will be processed and converted to text. A GUI interface with capability of control of the network of traffic lights, monitoring the images, and displaying the speed of the cars when the traffic violation occurred has been designed. In this system the mode of operation changes during the day for example in traffic congestion and at the times when fewer cars commute.

Project targeted applications: Traffic control at intersections a safer system for pedestrians