Keywords

1 Introduction

Nowadays, the number of blind people in China is the largest in the world, with more than 6 million blind people. Visual barriers seriously affect the blind people’s access to information and perception of the environment, making it impossible for them to travel normally, even in places they often visit and familiar environment, There are also all kinds of stumbling, let alone never set foot in the place, so if you want to go to a completely strange, never crossed street, but because you can’t get real-time road conditions, then their travel safety is difficult to achieve even the lowest guarantee, it’s just like this, many blind people don’t want to go out of the house, so they have no way to better integrate into the society and achieve their goals The value of life, which is a pity for the blind, is the loss of national and social resources, so it is urgent to effectively help the blind travel safely and normally [1].

The intelligent traffic light alarm system for the blind is designed to solve the problem of blind travel. It takes the single-chip microcomputer as the central controller, as the data collection terminal, identifies the traffic lights through the color recognition sensor, monitors the status of the traffic lights in real time, and transmits the information to the single-chip microcomputer. After data recognition and analysis, it finally identifies the blind with hardware modules such as voice synthesis broadcast module Voice warning [2].

2 Overall Design Scheme

The main body of this design is composed of two parts: the sender and the receiver. STC MCU module and wireless communication module are common at both ends of the transceiver. MCU module is used to collect data, and wireless communication module makes the sender and receiver communicate. The color recognition sensor module is unique to the transmitter, through this module to identify the traffic lights, the data information will be transmitted to the MCU. The receiving end analyzes and synthesizes the data received by MCU through its unique voice synthesis broadcast module, and finally completes the voice alarm for the blind. The general design scheme is shown in the figure below (Fig. 1).

Fig. 1.
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The overall scheme design

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Among the above two terminals, the transmitter needs at least one single chip microcomputer to collect and monitor the traffic light information in real time; one red, one yellow and one green LED light and three buttons to correspond with each other one by one to simulate the operation of road traffic lights; a wireless communication module [3] as the communication transmitter; at least one color recognition sensor to identify the color of LED lights, So as to judge the current traffic light situation. The receiver needs at least one single chip computer to receive and monitor the traffic light information; it needs a wireless communication module as the receiver to communicate; it needs a voice synthesis broadcast module [4] to process the received traffic light information, and finally broadcast it through voice synthesis.

2.1 Software Design of Transmitter

The function of the sender is to identify the traffic lights at the intersection through the color recognition sensor, and transmit the traffic light information to the MCU. When the judgment data is received, the information is transmitted to the receiver through the wireless communication module. The software design of the transmitter is as follows (Fig. 2).

Fig. 2.
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Software design flow chart of sender

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The function realization in the figure above is mainly completed by two processes, which complement each other. The first core task of the process is to complete the identification of the traffic lights at the intersection, mainly through the three primary colors principle in gy-33 module [5, 6]; the second core task of the process is to complete the judgment of the traffic lights at the intersection (red light, yellow light, green light or street light fault), select the current working mode of the street light, and complete the wireless communication with the receiver module.

2.2 Software Design of Receiver

The function of the receiver is to receive the traffic information transmitted by the sender through the wireless communication module, and send the traffic information to the MCU. After the MCU judges whether the data is red, yellow, green or no light, it sends the information to the speech synthesis broadcast module, and finally broadcasts the situation of the intersection to the blind, telling them whether they can pass at this time. The software design of the receiver is shown in the figure below (Fig. 3).

Fig. 3.
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Software design flow chart of receiver

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3 Design Features and Extension Description

3.1 Feature Introduction

This design is based on color recognition sensor, voice synthesis broadcast, wireless communication and MCU technology, combined with social phenomenon and demand, as well as new concept innovation. Whether from the selection of single chip microcomputer, different module selection and communication protocol scheme, or from the sender to the receiver, it is very different from the existing blind products in the market. This design uses today’s most common processor to complete an unusual design. Its characteristics are summarized as follows:

  1. (1)

    The color recognition module identifies the current traffic lights.

  2. (2)

    The sending end can collect and monitor the current traffic lights in real time through MCU.

  3. (3)

    The communication between transmitter and receiver can be completed by wireless communication module.

  4. (4)

    The receiver can receive the current traffic light information.

  5. (5)

    The receiving end can transmit the current traffic light information to the speech synthesis broadcast module through the single chip microcomputer.

  6. (6)

    The current traffic light information can be intelligently broadcast to the blind through the speech synthesis broadcast module.

Among them, the communication mode of this design uses the enhanced short burns protocol [7,8,9] of n0rdic company, as shown in the following Table 1.

Table 1. Enhanced short burns protocol form
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3.2 Extended Description

The intelligent traffic light alarm system for the blind can not only complete the functions described above, but also expand the following functions:

  1. (1)

    Real time monitoring the current traffic light information and the location of the blind through the mobile App.

  2. (2)

    It can be used together with relevant map navigation software to intelligently broadcast traffic lights during navigation.

  3. (3)

    The color recognition sensor can recognize traffic lights accurately and quickly.

  4. (4)

    It can realize long distance wireless communication.

4 Scheme Difficulties and Key Technologies

The difficulties of this design are as follows:

  1. (1)

    When the sender identifies the traffic lights at the intersection, it is easy to be affected by the surrounding environment, which leads to the recognition of the traffic light color is not fast and accurate enough.

  2. (2)

    The wireless communication module has a certain distance limit. If the transmission distance exceeds a certain range, wireless communication can not be realized, and the wireless communication module is installed at every traffic light intersection, which costs a lot of manpower and material resources in the early stage.

  3. (3)

    The circuit diagram and program design of receiver and transmitter.

The key technologies are as follows:

  1. (1)

    Gy-33 program modularization writing.

  2. (2)

    The sender software is written.

  3. (3)

    The software of receiver is written.

  4. (4)

    Enhanced short burns communication protocol setting.

5 System Simulation and Result Analysis

5.1 Overall Appearance of Intelligent Traffic Light Alarm System

The appearance design of the intelligent traffic light alarm system for the blind is shown in the figure. The whole design is divided into two parts: the sender and the receiver. The transmitter includes STC89C52 MCU, gy-33 color recognition sensor and nRF24L01 wireless communication module. The receiver includes nRF24L01 wireless communication module, STC89C52 MCU and xfs5152ce voice synthesis broadcast module (Fig. 4).

Fig. 4.
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Physical picture of intelligent traffic light alarm system for the blind

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5.2 Overall System Debugging

The debugging of the blind intelligent traffic light alarm system includes the debugging of the sender and the receiver. Among them, the overall debugging of this design also includes: traffic lights, color recognition sensor module, wireless communication module, intelligent recognition street lights, voice report debugging, etc.

Speech Synthesis Debugging.

Install the USB to TTL driver “ch340_341_32-bit.rar” or “ch340_64.rar” according to whether the computer system is 32-bit or 64 bit. After installing the driver, insert the USB-TTL module into the computer, open “my computer”, find the “device manager” in the “device” option, click “com and LPI port”, and then compare it with ch340. Open the “xfs5152ce PC demonstration tool” software, select the required port, write the required Chinese characters in the sent text, and then click “start synthesis” to synthesize the voice.

Wireless Communication Debugging.

If the functions of interrupt request (IRQ) and acknowledgement character (ACK) can be realized at the same time, after the communication is successfully completed: for the receiving node, the effective data that can be recognized as successfully received through the enhanced ShockBurst protocol is IRQ = 0; For the transmitting node, the received ACK = IRQ = 0 is returned by the receiving node (Fig. 5).

Fig. 5.
figure 5

Configuration process of CE and IRQ signals

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In the figure, after CE (yellow signal) = 1, about 10ms, that is, after the number of transmissions reaches the maximum upper limit, IRQ (green signal) = 0. There are two possibilities for this situation: the configuration of the transmitting node is inconsistent with that of the receiving node (the bytes or frequencies transmitted and received are different); There is no receiving node (Fig. 6).

Fig. 6.
figure 6

Send successful SCK and IRQ signals

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It can be seen from the figure that after sending the last SCK (green signal) signal of the first batch, IRQ (yellow signal) = 0 after 1ms at most (Fig. 7).

Fig. 7.
figure 7

SCK, IRQ, CE signal configuration process

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The logic shown in the figure above is as follows: Ce (purple signal) = 1. At this time, the transmitting node just completes the signal configuration process. Under different communication conditions, the phase of IRQ (green signal) of receiving node and IRQ (yellow signal) of transmitting node will also be different. For the above reasons, the ACK signal needs to be sent by the transmitting end for many times before the receiving end can receive it successfully.

Intelligent Broadcast Traffic Light Test.

Connect the power supply of sending end and receiving end, turn on the red light, yellow light and green light in turn, and place the color recognition sensor module above the LED. If the voice broadcast information is consistent with the street light, the system works normally.

6 Conclusion

After many times of program modification and system debugging, the design of the intelligent traffic light alarm system for the blind is completed, and all the expected functions can be achieved. The color recognition module, wireless communication module and voice broadcast module are all normal. The recognition accuracy of traffic lights, the agility of wireless communication and the accuracy of voice broadcast all meet the expected requirements. The significance of this design is to integrate the intelligent traffic light alarm system into the actual situation of social life, which can effectively solve the problem of blind travel. It is a major trend of social development, and also the aspiration of the people.