Applied Mechanics and Materials Online: 2013-09-27 ISSN: 1662-7482, Vols. 427-429, pp 1128-1131 doi:10.4028/www.scientific.net/amm.427-429.1128 2013 Trans Tech Publications, Switzerland Research of Intelligent Traffic Light Control System Design Based on the NI ELVIS II Platform Yuan Wang a, Mi Zhou b Polytechnic Institute, Sanya University, Sanya, 572022, China a email: wangyuan0155@163.com, b email: mizhou330@126.com Keywords: Intelligent Traffic Light Control System; NI ELVIS II Platform; Virtual Instrument Technology Abstract. In this paper, introduces a crossroads two-way intelligent traffic light control system based on the virtual instrument technology. The programming language Laboratory Virtual Instrumentation Engineering Workbench (LabVIEW) is used and the NI Educational Laboratory Virtual Instrumentation Suite II (NI ELVIS II) platform is chosen as target device in designing this control system. The control kernel of the system is LabVIEW program, it can realize lots of functions, such as adjusting the passing time in all directions and the duration of the yellow light, passing time count down and treatment of abnormal traffic. The experiment proves, NI ELVIS II platform than traditional experimental teaching equipment more innovative, flexibility and practicality, be helpful for students in the field of innovation ability training. Introduction Electronic courses have problems of obsolete experimental equipments and old-fashioned teaching method in some China's university. Traditional laboratory has the disadvantage of a variety of experimental equipments, high cost and single use. To update the experimental equipments need to invest a lot of money, and maintenance is difficult. Defects and shortcomings of traditional instruments have become increasingly prominent. Nowadays, experimental teaching has become one of the important links of talent training in China's university, and in the training of students' practical ability and innovation ability plays a very important role[1]. In recent years, with the development of measuring instrument to digital and computerized, traditional instruments have been gradually replaced by the virtual instrument. Virtual instrument is the use of customizable software and modular measurement hardware to create user-defined measurement systems[1]. Traditional hardware instrumentation systems are made up of pre-defined hardware components, such as digital multimeters and oscilloscopes that are completely specific to their stimulus, analysis, or measurement function. Because of their hard-coded function, these systems are more limited in their versatility than virtual instrumentation systems. The primary difference between hardware instrumentation and virtual instrumentation is that software is used to replace a large amount of hardware. The software enables complex and expensive hardware to be replaced by already purchased computer hardware; e. g. analog-to-digital converter can act as a hardware complement of a virtual oscilloscope. In this paper, introduces a new crossroads two-way intelligent traffic light control system which is based on the programming language LabVIEW and NI ELVIS II platform. This system is advantageous to have short design period, high reliability, easy operation and maintenance. LabVIEW and NI ELVIS II LabVIEW is a platform and development environment for a visual programming language from National Instruments. The purpose of such programming is automating the usage of processing and measuring equipment in any laboratory setup[2][3]. The programming language used in LabVIEW, also referred to as G, is a dataflow programming language. Execution is determined by the structure of a graphical block diagram (the LV-source code) on which the programmer connects different function-nodes by drawing wires. These wires All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, www.ttp.net. (ID: 130.203.136.75, Pennsylvania State University, University Park, USA-09/05/16,13:14:12)
Applied Mechanics and Materials Vols. 427-429 1129 propagate variables and any node can execute as soon as all its input data become available[3] [4][5]. Since this might be the case for multiple nodes simultaneously, G is inherently capable of parallel execution. Multi-processing and multi-threading hardware is automatically exploited by the built-in scheduler, which multiplexes multiple OS threads over the nodes ready for execution. LabVIEW ties the creation of user interfaces (called front panels) into the development cycle. LabVIEW programs/subroutines are called virtual instruments (VIs)[6][7]. The NI Educational Laboratory Virtual Instrumentation Suite (NI ELVIS) is a hands-on design and prototyping platform that integrates 12 of the most commonly used instruments including the oscilloscope, digital multimeter, function generator, arbitrary waveform generatorand, bode analyzer, digital reader, digital writer, dynamic signal analyzer, two-wire current voltage analyzer, three-wire current voltage analyzer, variable power supplies and impedance analyzer into a compact form factor ideal for the hardware lab or classroom. Based on NI LabVIEW graphical system design software, NI ELVIS, with USB plug-and-play capabilities, offers the flexibility of virtual instrumentation and allows for quick and easy measurement acquisition and display. This hardware platform helps educators teach a variety of concepts, including measurement and instrumentation, analog and digital circuits, controls and mechatronics, telecommunications[1]. System Design Design requirements.design requirements of the intelligent traffic light control system are as follows: (1) Alternative use of the red, yellow and green light in all directions, and the traffic lights of the relative direction have the same state. (2) The yellow light to blink 3 times in the process, in order to make the vehicles have time to stop in the forbidden line. (3) The passage time in all directions and the duration of the yellow light can be adjusted, and by default, the passage time in east-west and south-north direction is 30 seconds and 25 seconds respectively, the duration of the yellow light is 3 seconds. (4) Show the passing time, and can count down the passing time. (5) The system with an external interrupt control button, can into the interrupt program with the manual control. (6) In case of emergency, the system into the interrupt program, and all the red lights lit. (7) After the emergency, the system back to normal state. Hardware circuit.the hardware circuit of the intelligent traffic light control system is composed of four identical traffic light hardware circuit modules and four identical pedestrian signal light hardware circuit modules, in which the four traffic light hardware circuit modules are the core. (a) Protues schematic diagram (b) Printed circuit board Fig.1. The traffic light hardware circuit module The protues schematic diagram and printed circuit board of the traffic light hardware circuit module shown in Figure1 (a) and (b). The traffic light hardware circuit module is composed of two 7-segment displays, two common cathode BCD to 7-segment decoders(cd4511), three light
1130 Mechanical Engineering, Industrial Electronics and Information Technology Applications in Industry emitting diodes which the color is red, yellow and green respectively, three Triodes and some resistances. The CD4511 s function is to convert the logic states of a 4-bit BCD, and outputs the 7-bit signals which will drive the 7-segment LED display. The display shows the decimal numbers 0-9. The two 7-segment displays are show units and tens of the passing time. The input signal of triode controls the light emitting diode. When the triode input high, the light emitting diode lit. The input signals of traffic light hardware circuit module are follows: 4-bit BCD(A, B, C, D), tens 7-segment display s chip select signal, units 7-segment display s chip select signal, light emitting diode s control signal(red, yellow, green), VCC and GND. Pedestrian signal light hardware circuit module is composed of two light emitting diodes which the color is red and green respectively, two Triodes and some resistances. The schematic diagram of the pedestrian signal light hardware circuit module is same of the traffic light hardware circuit module. The input signals of pedestrian signal light hardware circuit module are follows: red light emitting diode s control signal, green light emitting diode s control signal, VCC(5V) and GND. Software program.the software program of the intelligent traffic light control system was programed by the LabVIEW. In the program, the passage time in all directions and the duration of the yellow light should be factitious setting. By default, the passage time in east-west and south-north direction is 30 seconds and 25 seconds respectively, the duration of the yellow light is 3 seconds, and the passage time ranges between 1 to 99. The yellow light to blink 3 times is to come true by the For Loop. And through the conditional terminal of the For Loop to realize into the interrupt program with the external interrupt control button. After the emergency, the system back to normal state. The units and tens of passage time and the duration of the yellow light are converted from a decimal number to 4-bit BCD. The logic states of all traffic lights are decided by the block diagram. The outputs of the LabVIEW program are inputted to NI ELVIS II platform through the Data Acquisition(DAQ) VIs, which include the 4-bit BCD, tens 7-segment displays chip select signal, units 7-segment displays chip select signal, light emitting diodes control signal, VCC(5V) and GND. The hardware circuit that connects traffic light hardware circuit modules, pedestrian signal light hardware circuit modules and NI ELVIS II platform over DuPont lines, and using the data line to connect NI ELVIS II platform and computer. The hardware circuit s test result of the intelligent traffic light control system shown in Figure2 (a), and the test result of the LabVIEW program shown in Figure2 (b). Through the test results, the system has been tested by practice, having reached the requirements. (a) The result of hardware circuit (b) The front panel of LabVIEW program Fig.2. The intelligent traffic light control system
Applied Mechanics and Materials Vols. 427-429 1131 Conclusion Through the LabVIEW and the NI ELVIS II platform to design an intelligent traffic light control system. The experiment proves, NI ELVIS II platform than traditional experimental teaching equipment more innovative, flexibility and practicality, be helpful for students in the field of innovation ability training. Acknowledgement In this paper, the research was sponsored by the Scientific Research Fund of Hainan Provincial Education Department (No.Hjjg2013-35) and Education Research Fund of Sanya University(No. Syxyjy120506). References [1] Li Jun. Traffic Light Control System Design Based on the NI ELVIS Platform[J]. Computer Knowledge and Technology.2010,6(32), 9123-9124. [2] Dr Cor J. Kalkman MD, PhD. LabVIEW: A software system for data acquisition, data analysis, and instrument control[j]. Journal of Clinical Monitoring,1995(1)51-58. [3] Inc. National Instruments Inc. LabVIEW 8 Student Edition[M]. Prentice Hall, 2006. [4] Surekha, P. LabVIEW based advanced instrumentation systems[m]. Phoenix Lieb press, 2009. [5] Jeffrey Travis; Jim Kring. LabVIEW for Everyone: Graphical Programming Made Easy and Fun[M]. Prentice Hall, 2007. [6] Tiernan, Peter. Enhancing the learning experience of undergraduate technology students with LabVIEW software[j]. Computers and Education. 2010, 55(4), 1579-1588. [7] Levent Sevgi, Agatay Uluisik. A Labview-Based Virtual Instrument for Engineering Education: A Numerical Fourier Transform Tool[J]. Turkish Journal of Electrical Engineering and Computer Sciences. 2006, 15(4).
Mechanical Engineering, Industrial Electronics and Information Technology Applications in Industry 10.4028/www.scientific.net/AMM.427-429 Research of Intelligent Traffic Light Control System Design Based on the NI ELVIS II Platform 10.4028/www.scientific.net/AMM.427-429.1128