Vehicle operation monitoring is a typical real-time monitoring system. As a real-time vehicle operation monitoring system, it is necessary to solve related technologies such as positioning acquisition, communication transmission processing, and graphic visual dynamic display.
At present, GPS global satellite positioning technology has become increasingly mature, and its dynamic positioning accuracy has fully met the needs of vehicle monitoring and positioning. The GPS installed on the vehicle can collect the current position information (longitude) of the vehicle and indirect information such as speed, direction, time, etc. in real time. With the help of the GSM national public mobile communication network, GPS information can be wirelessly transmitted to the monitoring center through signaling. The monitoring center parses and returns the GPS information, and uses the GIS graphics function to display the visual dynamic display of the graphics, and the GIS analysis function to perform the optimal and shortest route analysis for decision-making, command and dispatch. Therefore, the integration of GPS, GSM, and GIS can better solve the key technologies of position acquisition, communication transmission, and graphic display in the vehicle monitoring system.
Schematic diagram of the vehicle monitoring system. The car GPS sends the received GPS signal wirelessly to the GSM base station through the car's industrial mobile phone. After the base station receives the information, it transmits it to the mobile or China Unicom MSC (exchange). Center) SMSC and GIS * Center establish a connection communication by TCPP protocol through LAN or WAN. After receiving the information from SMSC, GIS * Center analyzes the data packet and displays the vehicle's positioning information, related database information retrieval and other control processing . Control process information transmission is the reverse transmission of the process of receiving information.
3. Functional requirements GIS map browsing, query and analysis functions complete the information query and statistics of all monitored vehicles.
Interactive two-way query of graphics and attributes.
Based on the query analysis of the map: point, line and area buffer target search, generate the shortest path and optimal path query of navigation information.
Communication processing Communication processing is mainly based on TCPP protocol, through the Winsock technology for limited transmission of computer local area network or wide area network, it specifically includes the following functions: â‘ dynamic control of communication data flow; â‘¡ receive GPS information, analyze and process GPS information; Request, alarm and other information.
Call the vehicle (group) for real-time tracking, generate a trajectory route, and automatically capture the road centerline (the threshold is automatically set).
Send control commands or short messages to the vehicle.
Historical playback of vehicle trajectory.
M uses SQLServer or Oracle large network database to support multi-user information sharing and concurrent processing.
Perfect data security protection, data backup, and data failure recovery functions.
The basic data information should satisfy basic operations such as vehicle information and related scheduling query, entry, and modification.
The software design of this system mainly involves the contents of map space data engine, GPS data receiving and processing, short message sending GPS data and vehicle control commands. The entire system structure is as follows.
~ DataBase (user enemy database) software structure block diagram. The second layer is the middle layer, which encapsulates the GIS and communication bottom layer; the third layer is the application system layer, and the GPS monitoring application system belongs to the application layer.
The GPS monitoring application system can be developed without having to worry about the underlying details, and only call the required functions to the COM components in the middle layer.
In fact, the middle layer itself is the encapsulation of the bottom layer, so as long as the functions provided by the middle layer are complete, it is an easy job for the application layer development and version upgrade maintenance. Therefore, this system structure has strong scalability and scalability.
According to the system structure, all functions related to GIS and communication processing are basically calling the COM component functions of the middle layer. Whether the GIS component functions are complete is not a major obstacle. The key is whether the functions of GPSX and SMCX are perfect.
Most of the map functions call the functions of the middle layer, and you can also directly call the functions of MapX. In fact, if you are familiar with the underlying functions of MapX, it is more flexible and convenient to call the corresponding functions directly.
To ensure that the map can be zoomed steplessly, according to different fields of view, automatically determine the physical loading of the graphic information to display, to speed up the display speed of the map.
1) Monitor, in order to ensure that all vehicles are in the field of view of the screen, the software should be able to automatically adjust the real-time display ratio.
To achieve the translation of different ranges and horizons of the map, the program should also provide the map eagle eye function so that there is a reference range when the map roams.
1) Monitor, in order to ensure that all vehicles are in the field of view of the screen, the software should be able to automatically determine the position of the translation, of course, it should also take into account the current proportion of automatic.
The automatic map switching function involves the management of map frames or the division of areas in the process of map processing. In order to avoid entering blind areas during vehicle monitoring, it must be divided by administrative areas. When a monitored vehicle is called, it can determine the area where the point falls based on the discrete location data it returns, and then determine whether the area map has been loaded. If it is not loaded, load the corresponding area map, there are two ways to implement: â‘ call the spatial analysis function of the relationship between MapX points and the area; â‘¡ pre-store the area boundary data of the block map, use the area function of Windows to first create an area, and Windows function of call point and area relationship.
Regardless of the above method, it is faced with whether to obtain a location point and do a large amount of calculation work for area judgment. In order to reduce the speed bottleneck, we can manually set the time interval of point judgment, and even according to the actual situation, the monitoring of some cars may not be judged by such a large operation.
The central fixed-point display mainly means that the user can lock a specific monitored vehicle, so that the tracked target always displays its running track in the current field of view and the current scale map. At this time, the map automatically shifts. In addition, when the user makes a query, it can also be displayed according to the characteristic location of the entity.
Communication processing this part of the function, mainly completes the communication of TCP / IP protocol through Winsock. Of course, the bottom layer also involves SMPP and CMPP protocols. This part of the function is best encapsulated by the middle layer, and the application layer directly calls the COM component function.
Dynamic control of communication data flow When the amount of communication data is large, the software should automatically balance the communication data flow. In this case, the time interval for the subsequent called vehicle to transmit data should be automatically limited, or the time interval for the called vehicle to return data can also be automatically adjusted. In the specific implementation, the display provides the minimum time interval available for selection, that is, the time interval for defining the call selected by the user.
Transmit the information, decode the information, determine the location, estimate the speed, determine the direction, positioning status, and the number of satellites. The key problem is how to determine the authenticity of the trajectory data, otherwise the trajectory data and the real data are quite different. Therefore, this function is best solved by the middle layer.
The monitoring software must answer the alarm information in real time and handle the alarm.
When the alarm message is received, the electronic map flashes and displays in the center of the field of view with the highest priority as the point of the accident. At the same time, the monitoring computer emits a beep and gives a prompt message. All the information of the current vehicle is immediately popped up on the screen, especially with The phone numbers of all the contacts related to the car, and it is only possible to automatically send a short message of alarm information to all contact phone persons. The police handling process should be such a process that the duty officer sends instructions such as fuel cut and power cut or transfer to 110 to execute the police department according to his authority.
Vehicle monitoring is the core of this application system. Provide real-time various information reports to the monitored vehicles or groups of vehicles, including the current vehicle speed, direction, stars, street or road name driving, coordinate longitude drop, track display and other information.
In order to facilitate the management of vehicles, the data is organized in a tree-like hierarchy, that is, the specific entry and access of data is carried out according to the administrative organization of the application department. Such a structure is convenient for designating a group of vehicles to be simultaneously selected and monitored quickly. In the design of the software interface, a tree-shaped human-machine interface can be provided.
After selecting the vehicle or vehicle group, find the corresponding SIM card number and vehicle platform in the database, you can send the call instruction to return the information, and display the real-time report information of the called vehicle (group) in the electronic data table . Of course, the user can select the target release tracking command in the list of monitored vehicles and instruct them to return data.
Call the display of the real-time tracking trajectory of the vehicle. The GIS in the vehicle monitoring system mainly provides visual and real-time location geographic maps for the location tracking, vehicle navigation, and fixed-point alarms of various locators. Effective navigation to shorten the time to deal with emergencies.
The vehicle monitoring system makes full use of the GPS satellite space positioning technology to complete the real-time location information collection of the vehicle; the GSM effectively solves the wireless communication transmission in the field, and the data transmission of the GSM short message greatly reduces the communication cost; Real-time dynamic positioning and visual display, as well as effective navigation and remote monitoring of operating vehicles. Judging from the actual operation of an oil transportation vehicle monitoring system of a company in Daqing, the processing bottleneck of the system lies in factors such as GSM bandwidth, GIS complex spatial analysis and decision-making, and GPS signal reception. When there are too many monitoring vehicles and the geographic location of the vehicle is not too wide, the system may not receive signals or receive delays. It is believed that with the development of GPS technology, the in-depth application of GPRS and the improvement of GIS spatial analysis technology, the above vehicle monitoring modes will have wider application prospects.
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