Implementation strategy of street lamp control and management system based on GIS

1 Problem Statement

With the rapid development of urban modernization, the automation control and management of municipal facilities are becoming more and more important. This paper proposes the design and implementation strategy of key technologies of urban street light automation control management system based on GIS.

The traditional street light control method is to control the switch manually or by timing clock. Since each road section is controlled independently and there are errors between each timer, the street lights are not turned on and off uniformly, and due to the lack of corresponding detection means, their working status cannot be monitored. In order to change this backward situation, the realization of automatic control and management of urban street lights has been put on the agenda.

2 System Design Goals

2.1 Intelligent terminal controller

We call the control device that controls the switch of a street light a terminal controller. To realize the control and management of street lights, we must first implement intelligent transformation on the existing controller.

2.2 Remote control of decentralized terminal intelligent controllers

In order to achieve uniform on and off of street lights, a central control mechanism is required to be responsible for unified control and management. Since the terminal controllers are scattered in various blocks, a remote control system needs to be established.

2.3 Establishing a GIS-based control and management system

In order to make the system a comprehensive system integrating control and management functions, and also to facilitate intuitive operation, detection, display and query of various information about street lamps, a GIS-based control and management system needs to be established.

3 System Functional Design and Implementation Strategy

3.1 Functional design of terminal controller

The terminal controller has three main functions: to control the switch of street lamps according to instructions; to complete the detection of street lamp conditions; and to achieve data communication with the central control management system. As shown in Figure 1:

Figure 1 Terminal controller function diagram

3.1.1 Implement street light switch control according to instructions.

The switch of street lights is controlled by the control unit. The control is mainly based on two aspects: one is to receive control instructions from the central control system through remote data communication, and the other is to automatically turn on or off the street lights after the control unit determines that the expected set value is exceeded. The latter is mainly used when the central control system or communication fails, and the control unit automatically forces the switch of street lights. In addition, it also makes corresponding judgments and handles abnormal working conditions.

3.1.2 Complete the lighting condition detection of street lamps.

The main purpose of light condition detection is to test the working condition of street lights.

3.1.3 Remote communication of terminal controller.

Remote communication is a means of information transmission for the central control management system to implement unified centralized control of each terminal controller, and is one of the technical keys to the realization of this system. Remote communication will be discussed in detail in the following "System Remote Communication Design and Implementation Strategy".

3.2 Functional design of central control management system

Construct a GIS visualized urban street light automation geographic information system, including the creation of visualized lossy graphics of urban basic geographic information, blocks, street light distribution, etc., to provide a support platform for visualized query, dynamic display and monitoring for street light control and management.

Construct a street lamp data database. The street lamp data database includes two aspects: one is the static data database, and the other is the dynamic data database. The main contents of the static data database include: the geographical location of the street lamp installation, the date of installation, the date of renovation, the specifications of the materials used (lamp poles, lampshades, bulbs, etc.), the power size, the rated illuminance index and other related data; the main contents of the dynamic data database include: street lamp working conditions, street lamp parameters, rated values, alarm values, current working current and working voltage, etc.

Figure 2 Central control management system

Construct the central control management module. The central control management module is a set of control management function modules based on GIS visualization and LAN operation platform. Its main functions include: setting of system initialization working parameters; database management and network database sharing management; management of central communication equipment and data communication (data communication will be discussed in detail in the "System Remote Communication Design and Implementation Strategy" later); through the data communication between the central communication equipment and the terminal street light controller, the terminal controller parameter setting, clock correction, switch command issuance, working status detection and other functions are realized; illumination detection. As shown in Figure 2.

4 System Remote Communication Design and Implementation Strategy

Remote communication of the system is a means to achieve remote control. Both wired and wireless methods can be used. The former involves many problems such as long-distance line laying and signal relay, which is difficult to operate in practice. This article focuses on the wireless method, which uses a master station to call multiple slave stations. The master station and the slave station use digital modulation radio stations with data communication interfaces. The master station radio is controlled by a central computer, and the slave station radio is controlled by a terminal controller. The power of the radio station depends on the length of the maximum control radius and the geographical environment. Since the master station has a large transmission power and high receiving sensitivity, the slave station power is usually set to one-fourth to one-third of the master station power.

4.1 Communication method

There are two communication methods, one is the master station broadcast method, and the other is the master-slave point-to-point method. The first method is mainly used for the development and transmission of public control instructions, such as switching lights, public parameters, clock correction, etc. The second method is mainly used for data transmission between the master station and a specific slave station. The slave station uses address coding to uniquely identify. The slave station sends data in a passive handshake mode. After the master station calls a slave station, the slave station sends data to the master station under the control of the terminal controller. The data content is mainly light condition information, system testing, etc. Under the control of the central computer, the master station transmits data in turn with the slave station, thereby realizing the real-time collection of light condition data of each section of street lights.

4.2 Communication data format definition

Any data communication must define the data format. Therefore, the general data format will not be described here, but it should be pointed out that in this communication mode, once the master station sends information, all slave stations receive it at the same time. Logically, whether to receive it is determined by the broadcast identifier or address code. In order to improve system efficiency, the length of the address code segment should be dynamic and can include multiple address codes, so that master-multiple slave stations can be realized in a non-broadcast mode.

5 Software Design Strategy

The software of this system is divided into two parts: one is central control management, and the other is terminal controller control detection.

5.1 Terminal control detection software

The terminal control and detection software is a software package based on a single-chip microcomputer. The control and detection parts are not very technically difficult. The focus is mainly on the data communication with the slave digital modulation radio and the data communication with the central control management system. The main process is shown in Figure 3.

Figure 3 Flowchart

5.2 Central Control and Management Section

In addition to completing the main front-end functions such as system control and detection, another important function of central control management is to provide a set of dynamic display functions of visual street lamp working conditions based on GIS. The refresh of the dynamic database is based on the detection of real-time lighting information, which is convenient for intuitively monitoring the dynamic information of lighting conditions through graphics. It also provides visual query and database management of the lighting condition database based on GIS. If the user unit has established an internal LAN, it can provide visual lighting condition information query to other relevant departments through data sharing, thereby greatly improving the efficiency and level of street lamp management. The main technical keys to achieve the above functions are:

Seamless integration of GIS, DBMS and application control modules; real-time visual refresh of dynamic data; multi-tasking concurrent system efficiency and low system resource usage.

5.2.1 Seamless integration of GIS, DBMS and application control modules.

Since GIS, DBMS and application control modules are oriented to three different application environments, if they are constructed separately, the entire system will inevitably not be able to work together on the same interface, thus making the system unable to become a unified whole. To solve this problem, platform support must be sought.

GIS selection.

The development of GIS is crucial to system integration.

After comparison, Maplnfo-Proserver was selected. It is a GIS platform working on Windows 9X or Windows NT. It supports OLE and DDE. All commands that can be used in the Maplnfo environment can be sent as OLE verbs, so that other host languages ​​(such as VB, VC, etc.) can directly start Maplnfo commands, thus realizing the perfect combination between other development tools and Maplnfo. As shown in Figure 4.

Figure 4

·About the interface between GIS and DBMS.

As a control system that introduces the concept of MIS, it is impossible to complete a large number of data management without the support of DBMS. MapInfo supports Client/Server architecture and has access interfaces for multiple DBMS, including almost all the commonly used DBMS (such as Oracle, Sybase, Microsoft Access, Informix, SQL Server, etc.).

MapInfo provides DDE and DLL, which are powerful tools for realizing these functions.

5.3 Real-time visual refresh of dynamic data

The dynamic data collected by the application control module needs to be displayed in real time in a visual way. Maplnfo provides a feature-rich DLL. The application control module can activate the corresponding functions of Maplnfo by calling the DLL. The dynamic data is converted into a format and displayed intuitively and dynamically at the corresponding position on the constructed city map in the form of graphic color, flashing changes, etc., thereby achieving dynamic refresh of GIS visualization.

5.4 Multi-tasking system efficiency and low system resource usage

Although Windows 9X supports multi-tasking concurrency, it is not difficult to find in actual applications that when multiple application processes request system resources at the same time, the system efficiency will drop sharply. In this system, when the application control module transfers control to Maplnfo, due to the real-time requirements of data acquisition and control, the application control module cannot be in a suspended state. However, if the application control module is in a fully activated state, the system will respond to other requests (such as user-activated Maplnfo applications, etc.) at a speed that is unacceptable. Therefore, it is necessary to ensure the real-time requirements of the application control module while preventing the application control module from occupying too many system resources unnecessarily. The effective way to solve this problem is:

When designing the application control module, all parts with real-time requirements are activated by the time control. Its status is shown in Figure 5:

With this technology, when the application control module is in a dormant state, its system resource usage is relatively low, which can speed up the system's response to other tasks.

Figure 5

6 Conclusion

This article describes a relatively complete GIS-based urban street light control and management system, aiming to provide some implementation strategies for key technologies in the integrated design of composite systems. These technologies are not only applicable to the application of this system, but also have a certain reference role for some system integrations in multi-platform environments, such as dynamic positioning and tracking systems under GIS and GPS global satellite positioning systems, and fire alarm positioning systems based on GIS. In view of the limited time and the author's limited level, please correct me.