Design of bus anti-overload intelligent voice prompt system

O Introduction
For most urban residents, the public transportation system is in contact with them every day. However, with the accelerated development of urbanization. With the rapid growth of the urban population, the urban public transport system has become more and more crowded. The public generally feels that it is difficult to get on the bus and the car is uncomfortable. At the same time, due to the prevalence of bus overload, there are certain security risks. At 8:25 on June 5, 2009, a "Chuan A49567" 9 bus near the North Third Ring Road in Chengdu burned, killing 72 people and injuring 72 people. It is worth noting that the overloaded traffic load has increased the loss of the accident, and behind it is the public transportation after the acceleration of urbanization. In fact, the bus problem encountered in Chengdu is also national.
From the current legal point of view, it is not too difficult to characterize the bus overload standard. The Road Traffic Safety Law clearly states that the standard for defining the number of nuclear carriers is the number of nuclear carriers on the driving license issued by the public security organs for motor vehicles. Generally speaking, it is based on the number of seats set when the motor vehicle is shipped from the factory. Then, according to the Road Traffic Safety Law, whether the bus is overloaded is clear at a glance. Based on the above reasons, this paper proposes an intelligent anti-overload and voice prompting system. The system controls the reflective infrared sensor to realize the vehicle population statistics of the bus through the single-chip microcomputer, and displays it through the 12864LCD. When the number of vehicles exceeds the upper limit of the vehicle, Under the control of the single-chip microcomputer, the ISD4004 voice module will issue a voice prompt message, thereby achieving the purpose of intelligent control against overload.

1 System principle The principle block diagram of this system is shown in Figure 1. It consists of AT89S52 single-chip microcomputer, reflective infrared counting module, 12864LCD display module and ISD4004 voice prompt module. The system collects the number of passengers on the bus through the reflective infrared counting module, and sends it to the single-chip microcomputer, and then controls the 12864LCD to display the current number of passengers through the single-chip microcomputer. When the number of passengers exceeds the limit of the vehicle, the ISD4004 voice module will perform voice prompts to realize intelligence. control function.

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2 system hardware components
2.1 Reflective infrared counting module (1) E18-D80NK sensor E18-D80NK sensor is an infrared reflective proximity switch sensor, which can be used for reflective detection of objects (such as obstacle detection, pipeline counting, access control system, automatic punching) Water system, etc.). The sensor has the advantages of small volume, low energy consumption, convenient application, stability and reliability. The application circuit of the E18-D80NK sensor is shown in Figure 2.

(2) Reflective infrared counting circuit The circuit diagram of the reflective infrared counting module is shown in Figure 3. The system is controlled by two AT89S52 single-chip microcomputers, one of which is the master for the front door and the other is the slave for the back gate counting. . Four E18-D80NK sensors (R/T1 and R/112 for the front door, R/T3 and P/T4 for the back door) are used to detect the number of people; an LCDl2864 is used to display the current number of people. P/T1 and P/T2 are placed side by side. When P/T1 detects a signal first and R/T2 subsequently detects a signal, it indicates that someone is on the train and the counter is incremented by one; and when R/T2 first detects a signal and P/T1 detects a signal, Indicates that someone gets off the bus and the counter is decremented by one. In other cases, the counter does not change. The R/T3 and P/T4 are placed and counted in the same way as R/T1 and R/T2. When the slave detects that someone is getting on or off through the infrared sensor (R/T3 and R/T4), different flag bits can be set separately; the slave sends the flag bit to the host through the serial port, and the host receives the different flag pairs according to the received The counter is incremented or decremented by one; the host itself can also detect the person getting on and off the vehicle through the infrared sensors (R/T1 and P/T2), and add or subtract one counter according to the situation of the person getting on and off; After that, control LCDl2864 to display the current number of people on the car.

2.2 ISD4004 voice prompt module ISD4004 voice prompt module circuit shown in Figure 4, it is mainly composed of ISD4004 voice chip and peripheral circuits. The input of the ISD4004 is an analog input signal that can be connected to a resident microphone to record sound. As can be seen from the figure, there is less connection between AT89S52 and ISD4004, and P1.1 is connected to the chip select pin of ISD4004. . Used to control the gating of the ISD4004. P1.2 is connected to the serial input pin MOSI of the ISD4004 to read the address of the playback from this pin. P1.3 and P1.0 are connected to the serial clock pin SCLK and the serial output pin MISO of the ISD4004, respectively. The output of the ISD4004 is connected to the LM386 power amplifier. The LM386 is an audio power amplifier produced by National Semiconductor.

2.3 LCDl2864 display module LCDl2864 display module circuit shown in Figure 5. This module is mainly composed of AT89S52 and LCDl2864. LCDl2864 is a Chinese character library with 4/8-bit parallel, 2-wire or 3-wire serial interface. The dot matrix graphic liquid crystal display module including the national first-level and second-level simplified Chinese character library has a display resolution of 128x64. The parallel interface method is used in this circuit, which can speed up the display. And the program code is simple. The LCD12864 data port in Figure 5 should be connected to a pull-up resistor to make the display clearer. When programming Chinese characters, you must first set the position of the displayed characters and then write the character code. When LCDl2864 receives an instruction, it must first confirm whether the module is in a non-busy state, that is, first detect the BF busy flag. Send the command again.

3 system software design The software program flow of this system is shown in Figure 6. When the system is powered on, the system must be initialized first, then the display subroutine is called, and then the reflective infrared detection module is run to collect information. When the passenger gets into the car, the counting plus program is called to increase the counter by one, and it is judged whether the vehicle limit is reached. If the counter does not reach the vehicle limit, the display subroutine is returned to continue scanning; if the counter reaches the vehicle limit, the call is made. The voice prompting program simultaneously issues the relevant overloaded prompt voice. Similarly, if a passenger gets off the vehicle, the count reduction procedure is called to decrement the counter by one and return to the display subroutine to continue scanning.

4 Conclusion The intelligent bus anti-overload voice prompt system designed in this paper mainly implements two-way reversible counting function by installing a pair of E18-D80NK sensors on the front and rear doors of the bus. When installing the system, it is required that each pair of E18-D80NK sensors should be placed side by side, and each pair of sensors should be kept at a distance of 3 to 5 cm so that passengers can pass each pair of sensors in succession to make accurate judgments. At the same time, the circuit connections must be accurate. The system can automatically perform up and down counting according to different movement directions of the human body, and can accurately determine and detect the passengers from the front and rear doors. This method breaks through the limitations of the one-way reflective infrared counter. After repeated tests, the system works stably and reliably, has strong anti-interference ability, the counting device is sensitive, the counting is accurate, the voice prompt function is perfect, and the real-time requirement can be met.