In this paper, a PLC-based intelligent control experiment device for traffic lights is developed. The device not only has some conventional control functions, such as north-south, east-west red and yellow light cycle start; countdown display time; manual adjustment of traffic lights; emergency traffic control, etc., can also be based on the traffic volume of the main and secondary roads Automatically adjust the time when the traffic light is on; it can adjust the time when the traffic light is on according to the time period. In addition, this paper adopts an easy-to-implement cycle-based automatic switching method based on the vehicle flow ratio, which eliminates the need for complex calculations when adjusting the time length of the traffic light, thus simplifying the PLC programming. The designed control system has high reliability and good real-time performance. Features.
1, system design ideasThe whole system adopts touch screen as the upper computer, PLC is the main control core, photoelectric switch and sound sensor are vehicle detection components, traffic lights and digital tube are the main control objects. The overall design idea is shown in Figure 1. In the intelligent working mode, the system can calculate the optimal time value of the traffic light in the next cycle according to the traffic volume of the road in each working cycle of the traffic light. Based on this, the PLC automatically controls the traffic light to be illuminated by the PLC control mode. Time, and can adjust the time when the traffic lights are on according to the time period. When special vehicles (such as ambulances, fire engines) arrive, they can also automatically activate the rushed traffic mode. In the figure, the touch screen is an intelligent control device, which can realize remote control and system status display, and can realize the switching of the working mode, which is used to replace the traditional button input, and can monitor the working state of the traffic light in real time.
Figure 1 Traffic light control system structure
2. System component selection and hardware structure designThe upper computer in this device uses the eViewMT4300C touch screen. eViewMT4300C touch screen has 5.6" 64KTFT color LCD display, providing 320 & TImes; 240 pixel resolution, with a variety of communication ports. Due to its good interface, versatility, flexible control, easy programming, low price, etc., in the industry The field of control has been widely used.
In terms of PLC selection, according to the control requirements of the system, 4 mode selection switches are required, 4 sensors for east and west and north-south direction sensors, and 4 sound sensors for 4 directions. Since the north-south vehicle detection sensor can share one input point, the east-west vehicle detection sensor can share one input point, and the four-direction sound sensor can share one input point, so the system needs a total of seven input points. The output part needs to control the signal light and the countdown time display, as well as the crosswalk light, etc., wherein the signal light requires 6 output points, and the crosswalk light can share the output point with the signal light. Since only one bit countdown data is displayed, the countdown display in four directions requires 16 output points, so the entire system requires 22 output points. The digital tube uses the conventional 2HS228021 model digital tube for the countdown display of 1 bit time. The sound sensor is replaced by a voice-activated switch. The hardware wiring diagram of the entire PLC control system is shown in Figure 2.
Figure 2 PLC control system hardware wiring diagram
3, system software designThe software design of the intelligent traffic light PLC control experimental device includes two parts: touch screen configuration software design and PLC control program design. The configuration software design mainly designs the operation screen of the touch screen, which is convenient for human-computer interaction. The PLC control program mainly realizes the cyclic display function of the traffic light and the digital display function of the countdown.
Transparent Led Film Screen,Adhesive Transparent Led Display,Adhesive Led Transparent Film Screen,Transparent Led Display Film Screen
Guangdong Rayee Optoelectronic Technology Co.,Ltd. , https://www.rayeeled.com