1 Overview
GPS measurement system for measuring vehicle moving objects such as braking distance, turning radius, acceleration and other indicators.
Installed on the target system using the NovAtel GPS receiver and antenna real-time measurement, real-time display, storage /
Output of motor vehicles and other moving objects in location (the location of the geodetic coordinates and rectangular coordinates), trajectories curve, the East / North to the speed, the East / North to the acceleration, mileage, (between two) away.
2 System Architecture
2.1 System components and working principle
System composition 2.1.1
The system block diagram shown in Figure 1, which is mainly constituted by two subsystems: base station subsystems and mobile station subsystem.
2.1.1.1 base station subsystem
Base station installed at a fixed location, the GPS receiver and antenna, wireless data transmission transmitting station and antenna, etc., used to measure the number of GPS differential correction and send.
2.1.1.2 Mobile Station Subsystem
Mobile stations installed in the tested vehicle on the GPS receiver and antenna to receive radio and wireless data transmission antenna and laptop computer (including real-time monitoring software and post analysis software), etc., used to test the target speed, position and status parameters.
2.1.2 Working Principle
System uses real-time differential measurement mode.
GPS base station receiver antenna laid in position on the measuring point known to receive GPS satellite signals, COM2 port to connect to the data transmitter, the output RTCA differential corrections (which may be software or GPSolution Windows HyperTerminal software settings), baud rate set to 38.4kbps, each 2s base station to send a group of observation data frame RTCAOBS, send every 10s a group of base station location data frame RTCAREF.
Mobile station GPS receiver was placed on measuring the motor vehicle to receive GPS satellite signals, the COM2 port to connect to the data transmission receiving stations, the baud rate is set to 38.4kbps, COM1 port to connect laptop computers, the baud rate is set to 115.2 kbps, COM2 to receive from the base station differential corrections sent by the real-time differential GPS COM1 output after the adoption of real-time track information data 20Hz (20 times per second output BESTPOSB and BESTVELB statements), notebook computer through COM1 to receive real-time data, by real-time monitoring software, and on the vehicle's trajectory, velocity, acceleration and other motion parameters and the system working state information in real-time monitoring display and record.
Data radio transmission rate is set to 19.2kbps, serial baud rate is set to 38.4kbps.
After the test task, after the analysis software can record real-time monitoring software, real-time data processing and analysis.
2.1.3 Software Features
Software running on Windows2000/Windows XP environment.
2.1.3.1 Real-time monitoring software
Real-time monitoring software, the following functions:
? Be documented real-time mobile station differential GPS receiver results of data;
? To speed, acceleration table, heading the table, numerical display mode shows the vehicle track, speed, heading, acceleration parameters;
? Instrument properties can be modified;
? Track map with latitude and longitude / Cartesian coordinate system as the background to display latitude and longitude / Cartesian grids;
? Can display the ruler;
? Achieve latitude and longitude and to switch between rectangular coordinates, and has zoom, pan and location automatically on the display;
? Track map can be displayed full-screen, and speed tables can also be the same screen display;
? Track map shows the track of the refresh rate for 1Hz;
? Able to view the different display GPS positioning state, when the query state, showed that the point of GPS positioning status;
? Able to calculate the track map the distance between any two points;
? Able to display a high degree of - time, speed - the time, acceleration - time curve; the curve shows, the need to meet the requirements are as follows:
? Timeline alignment;
? To achieve the overall drag curve;
? Hit punctuation synchronous display in the curve;
? Data to be used and the entire second half a second display;
? Achieve overall query, query results using the vertical alignment;
? Curve shows the default parameters are visible;
? Markers in real time recording;
? Can query any displayed point of property values;
? Can show time and Beijing time experiment;
? Able to print the output trajectory map, the user can select the print style.
2.1.3.2 Data Analysis Software
Data analysis software to achieve the following functions:
? Read data files and data to playback time basis;
? To speed, acceleration table, heading the table, numerical display mode shows the vehicle track, speed, heading, acceleration parameters;
? Instrument properties can be modified;
? Track map with latitude and longitude / Cartesian coordinate system as the background to display latitude and longitude / Cartesian grid;
? Can display the ruler;
? Achieve longitude and latitude, and to switch between rectangular coordinates, and has zoom, pan, and place automatically in the display;
? Track map can be displayed full-screen, and speed tables can also be the same screen display;
? Track map shows the track of the refresh rate for 1Hz;
? Able to view the different display GPS positioning state, when the query state, showed that the point of GPS positioning status;
? Able to calculate the track map the distance between any two points;
? Able to display a high degree of - time, speed - the time, acceleration - time curve; the curve shows, the need to meet the requirements are as follows:
? Timeline alignment;
? To achieve the overall drag curve;
? Hit punctuation synchronous display in the curve;
? Data to be used and the entire second half a second display;
? Achieve overall query, query results using the vertical alignment;
? Curve shows the default parameters are visible;
? Can query any displayed point of property values;
? Can show time and Beijing time experiment;
? Able to print out track map and the curves, the user can select the print style.