Precise positioning and speed measuring system and method for magnetic suspension train
Technical Field
The invention relates to a precise positioning and speed measuring system and method for a magnetic suspension train, belonging to the technical field of magnetic suspension train positioning.
Background
At present, 6 months and 13 days in 2017, the Beijing S1 line completes the hot skid test of the first stage, and passenger carrying and commissioning are expected to be realized within the year. In 2016, in 5 months, the first medium-low speed magnetic levitation line which is completely and independently researched and manufactured in China, namely the long sand magnetic levitation project, is put into operation formally, and the medium-low speed magnetic levitation commercial operation line has the longest running mileage in the world so far. The first magnetic suspension commercial transport line developed by Zhongde corporation in the world formally starts to operate in Shanghai on the 1 st and 4 th months in 2003, and the full length of the special line is 29.863 km. It belongs to the field of high-speed magnetic suspension train, and its operation speed is 430 km/h. Moreover, as the only high-speed magnetic levitation commercial operation line in the world, the magnetic levitation Shanghai demonstration line has been safely and stably operated for 5200 days to the beginning of 2017, the operation mileage is 1627 ten thousand meters, the passenger carrying capacity is 4814 ten thousand people times, and the highest operation punctuality rate (99.84%) and punctuality rate (99.92%) records of the ground transportation means are kept all the time.
In foreign countries, the construction of the Japanese superconducting high-speed magnetic levitation project continues to be promoted; hyperloop one in the United states achieves test speeds of over 1000 km/h.
In such accurate operation, precise positioning of the train is of particular importance. However, for a common wheel-track railway, the position and speed of the train are mainly determined by a track circuit and photoelectric encoders mounted on wheels, and since the maglev train has no wheels and there is no contact between the train and the track during operation, a conventional railway measurement method cannot be used for measuring and positioning the speed of the maglev train, and a new speed measurement and positioning method must be researched.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a precise positioning and speed measuring system and method for a magnetic suspension train, which can reduce code reading errors caused by electromagnetic interference of a magnetic suspension guide rail and effectively improve positioning and speed measuring precision.
The invention is realized by the following steps:
the invention provides a precise positioning and speed measuring system of a magnetic suspension train, which comprises a positioning module, a control module and a display module,
the positioning module comprises a vehicle-mounted active laser transmitter, a guide rail positioning mark plate and a vehicle-mounted laser receiver, wherein the guide rail positioning mark plate contains positioning information codes;
the control module comprises a signal processing circuit and a controller, the controller comprises a hardware part and a software part, the hardware part in the controller comprises a main board circuit and a microcontroller, and the software part in the controller comprises a decoding program and a detection program;
the display module comprises a communication device and an LED display screen.
Furthermore, the vehicle-mounted active laser transmitter and the vehicle-mounted laser receiver both comprise a high-frequency transmitting module.
Furthermore, the positioning information code contained in the positioning mark plate at the guide rail adopts a Gray code coding mode.
The invention also provides a method for accurately positioning and measuring the speed of the magnetic suspension train by using the magnetic suspension train accurate positioning and speed measuring system, which comprises the following steps:
1) the system is started, initialization setting and self-checking are carried out, whether vehicle-mounted active laser transmitters and receivers on two sides of the train can normally receive and send laser is automatically checked, then a display screen is initialized, and departure of the maglev train is waited after initialization and self-checking are successful;
2) a positioning mark plate containing positioning information codes is installed at a track along the suspension train, and a vehicle-mounted active laser transmitter rapidly transmits laser at a high frequency to scan the positioning mark plate;
3) laser emitted by the vehicle-mounted active laser is reflected by the positioning mark plate and then is received by the vehicle-mounted laser receiver, and the transmission speed of the laser is very high, so that the steps are almost completed at the same time;
4) after the vehicle-mounted laser receiver receives the information, the information is transmitted to a signal processing circuit in the control module, and the next step is rapidly carried out after the information is processed;
5) at this time, after the controller in the control module receives the processed information, whether the coding information of the positioning mark plate is wrong is detected through the detection program, and then the coding information is sent to the decoding program after the correctness is confirmed, so that the positioning coding information on the positioning mark plate is decoded.
6) After the decoded information is obtained, train position information and speed information can be obtained through a series of arithmetic processing.
Furthermore, after the position information and the speed information of the train are obtained, a display screen in the display module is controlled to display the information.
Furthermore, the LED display screen in the display module does not need to display information in real time, and only needs to update the position information and the speed information every few seconds; and meanwhile, the countdown display of the expected arrival at the terminal is also carried out, and the communication device transmits the speed and the positioning information of each carriage to a cab and related traffic departments so as to facilitate the passengers to know the train condition in time.
The invention has the following beneficial effects:
the invention improves the traditional precise positioning and speed measuring system of the magnetic suspension train, and comprises a positioning module, a control module and a display module; the positioning module comprises a vehicle-mounted active laser transmitter, a positioning mark plate at the guide rail and a vehicle-mounted laser receiver; the control module comprises a signal processing circuit and a controller; the display module comprises a communication device and an LED display screen. Compared with the traditional magnetic suspension positioning system, the laser transmitter adopted by the invention can more accurately read the coding information of the positioning mark plate, reduces the code reading error caused by the electromagnetic interference of the magnetic suspension guide rail and effectively improves the positioning and speed measuring precision.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic diagram of a precise positioning and speed measuring system for a maglev train according to an embodiment of the present invention;
FIG. 2 is a general flowchart of an implementation of a precise positioning and speed measuring system for a maglev train according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of a positioning mark plate of a precise positioning and speed measuring system for a maglev train according to an embodiment of the present invention;
fig. 4 is a gray code conversion table of the precise positioning and speed measuring system of the maglev train according to the embodiment of the present invention;
FIG. 5 is a flow chart illustrating a controller detection procedure of a precise positioning and speed measuring system for a maglev train according to an embodiment of the present invention;
fig. 6 is a schematic flow chart of controller software of a precise positioning and speed measuring system for a magnetic levitation train according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1 to 6, an embodiment of the present invention provides a precise positioning and speed measuring system for a maglev train, including a positioning module, a control module and a display module; the positioning module comprises a vehicle-mounted active laser transmitter, a positioning mark plate at the guide rail and a vehicle-mounted laser receiver; the control module comprises a signal processing circuit and a controller; the display module comprises a communication device and an LED display screen.
The active laser transmitter and the vehicle-mounted laser receiver in the positioning module both comprise a high-frequency transmitting module, and the vehicle-mounted laser transmitter and the vehicle-mounted laser receiver form a laser ranging sensor (forming a laser range finder) for convenient installation. The invention adopts FBM300-GT70 series in the high-precision laser measurement of a triangulation distance sensing system of Casati company in Germany. The measurement frequency of the FBM300-GT70 series can reach 1100 KHz. Considering that Laser emitted by the Laser emitter can be harmful to human bodies, Laser wavelength 685nm red visible Laser is adopted, the protection level can reach IP64, and adverse effects of rain, dust and the like on the instrument can be reduced. The operating voltage of the FBM300-GT70 series is 24VDC, 280mA, the equipped output signal interface is Ethernet (Ethernet), the transmission rate can reach 10M, and the measured data can be rapidly transmitted to the control module.
The positioning mark plate at the guide rail in the positioning module contains coded information. The invention adopts a Gray code coding mode. The gray code is a group of numbers in which any two adjacent codes have only one binary digit difference, and the maximum number and the minimum number have only one digit difference. The gray code belongs to reliable coding and is a coding mode with minimized errors. Although the natural binary code can be converted directly to an analog signal by a digital-to-analog converter, in some cases, for example, each digit of the binary code changes from 3 to 4 decimal digits, which can cause the digital circuit to generate large spikes in current. Gray code does not have this disadvantage, it only has one bit to change when switching between adjacent bits, it greatly reduces the logic confusion from one state to the next. Since only one bit is different between two adjacent code groups of the codes, in the conversion of the corner displacement quantity of the direction to the digital quantity, when the corner displacement quantity of the direction changes slightly and the digital quantity possibly changes, the Gray code changes only one bit, so that the method is more reliable compared with the case that other codes change two or more bits simultaneously, and the possibility of errors can be reduced. The invention adopts 10-bit Gray code coding. The positioning mark plate is a tooth similar to a square wave, and when the laser of the laser emitter scans on the tooth, the measured distance value is smaller and is 0 of a Gray code; when the laser scanning of the laser transmitter is at the hollow part, the measured distance value is larger, so that larger jump occurs, and the gray code can be simply judged to be 1. The width of the square wave teeth is 5mm, the hollow teeth are also 5mm, and the total is ten, so that 50mm is formed, and a small period is formed. Because the invention adopts 10-bit Gray code encoding, 1024 different numerical values, namely 1024 small periods, exist; when the 1024 values are scanned, that is, the distance of 512m, it is a large period. The controller can know the running distance of the magnetic suspension train by accumulating the times of the large period and the small period, and can know the specific position of the magnetic suspension train by comparing with the running route of the magnetic suspension train, thereby achieving the purpose of positioning the magnetic suspension train; the controller calculates the time T taken to travel N cycles and then divides the distance of the N cycles by the time T.
The signal processing circuit contained in the control module is mainly used for eliminating the influence of a huge magnetic field generated by a magnetic suspension train guide rail on an output signal of a laser ranging sensor consisting of a vehicle-mounted laser transmitter and a vehicle-mounted laser receiver, which is also the reason for adopting the Gray code for coding.
The controller contained in the control module is composed of two parts, namely hardware and software, the hardware part of the controller can be divided into two parts, wherein one part is a main board circuit, and the other part is a Microcontroller (MCU). The microcontroller adopts STM32F407 series chips of Italian semiconductor company, the highest working main frequency of the chips can reach 168MHz, the STM32F407 has 210DMIPS/566CoreMark performance when the chips are executed from a Flash memory under 168MHz frequency, and an ART accelerator of the Italian semiconductor is utilized to realize a FLASH zero-waiting state, which provides favorable conditions for quickly realizing decoding and improves the real-time property of the magnetic suspension positioning speed measuring system. The STM32F407 chip also has rich connection functions and is an innovative color-emitting peripheral, such as an Ethernet MAC10/100 interface meeting the requirements of the IEEE 1588 v2 standard, and information passing through a signal processing circuit can be quickly transmitted into and stored. The main board circuit mainly comprises a crystal oscillator circuit, an A/D conversion circuit, a reset circuit and a power circuit. The requirements on the crystal oscillator are high because the huge magnetic field generated by the magnetic levitation track has an effect on the crystal oscillator circuit and also provides a frequency of 168 MHz. The A/D conversion circuit is used for converting an analog signal output by a laser ranging sensor consisting of a laser transmitter and a vehicle-mounted laser receiver into a digital signal and then sending the digital signal to an STM32F407 chip for calculation.
The controller contained in the control module is composed of hardware and software, and the software mainly comprises a detection program and a decoding program. The detection program has the effect that when the maglev train body shakes and other conditions cause that the vehicle-mounted laser transmitter can not normally scan the coded information of the positioning mark plate, such as misreading, missing reading and the like. After the detection program starts, firstly judging the running direction of the magnetic suspension train, judging whether a group of positioning mark plate information is read completely, if so, judging whether the positioning mark plate is read for the first time, if so, recording the coding information, and if not, comparing the coding information with the reading result of the previous group; and if the comparison result shows that the information of the positioning mark plate is satisfied, the sensor is normal, otherwise, the sensor is judged to have code reading fault. The decoding program is used to convert the 10-bit Gray code determined by the detection program to binary code, and FIG. 4 shows the Gray code conversion table in the present invention. After the conversion into binary codes, the calculation can be carried out.
The display module comprises a communication device and an LED display screen. And the STM32F407 transmits the calculated positioning speed measurement information to the LED display screen through the HDMI digital high-definition interface. But cannot absorb such fast information due to the visual pause of the human eye. The display screen displays the distance traveled by the magnetic suspension train, the specific time and date and the real-time speed at the time, updates the distance at intervals of 3 seconds and updates the speed at intervals of 2 seconds. The communication device also transmits the speed of each compartment to the cab and the related traffic departments so that the passengers can know the train condition in time.
The invention also provides a method for positioning and measuring the speed of the magnetic suspension train by using the precise positioning and speed measuring system of the magnetic suspension train, which comprises the following steps:
1) the system is started, initialization setting and self-checking are carried out, whether the vehicle-mounted active laser transmitters and receivers on the two sides of the train can normally receive and send laser is automatically checked, and then the display screen also starts initialization. And waiting for departure of the magnetic suspension train after the initialization and self-checking are successful. The position mark plate containing position information code is installed on the track of the magnetic suspension train, and the vehicle-mounted active laser transmitter can quickly emit laser at higher frequency to scan the position mark plate. Laser emitted by the vehicle-mounted active laser is reflected by the positioning mark plate and then received by the vehicle-mounted laser receiver, and the transmission speed of the laser is very high and almost finished at the same time. At the moment, the vehicle-mounted laser transmitter and the vehicle-mounted laser receiver form a laser ranging sensor.
2) The positioning mark plate contains Gray code coding information, the invention adopts 10-bit Gray code coding, 50mm is a small period, and 512m is a large period. When the magnetic levitation vehicle arrives at different positions, the coded information contained in the positioning marking plates at the guideway during the same large period is also different. And scanning the information of the positioning mark plate by a laser ranging sensor consisting of a vehicle-mounted laser transmitter and a vehicle-mounted laser receiver, and entering the next step after scanning.
3) And the signal processing circuit processes the information obtained in the last step so as to eliminate the influence of a huge magnetic field generated by the guide rail of the magnetic suspension train on the output signal of the laser ranging sensor consisting of the vehicle-mounted laser transmitter and the vehicle-mounted laser receiver.
4) At this time, after the controller in the control module receives the processed information and the main board circuit in the hardware is subjected to A/D conversion, whether the coding information of the positioning mark plate is wrong or not is detected through the detection program, and then the decoding program is sent after the fact that the coding information is not wrong is confirmed, and the positioning coding information on the positioning mark plate is decoded. After the information is decoded, the distance traveled by the magnetic levitation train and the real-time speed of the train are obtained through a series of calculations.
5) The LED display screen of the display module obtains the running distance of the magnetic suspension train through an HDMI digital high-definition interface connected from the control module through the communication device, and updates the distance once every 3 seconds; real-time speed information of the maglev train is also obtained and updated every 2 seconds. But also the countdown expected to arrive at the terminal. The communication device also transmits the speed of each carriage to the cab and the related traffic departments so that the drivers can know the train condition in time.
The invention aims to provide a precise positioning and speed measuring system and method for a maglev train.
Along with the rapid development of economy, in the face of traffic pressure which is more and more crowded, the magnetic suspension train has low noise, high speed, safety, stability, energy conservation and environmental protection, so the magnetic suspension train is more and more valued by people. The invention discloses a precise positioning and speed measuring system and method for a magnetic suspension train, which perfects the absolute positioning technology of the magnetic suspension train, and scans the positioning information of a positioning mark plate at a guide rail through a laser ranging sensor consisting of a vehicle-mounted laser transmitter and a vehicle-mounted laser receiver to obtain the distance and the real-time speed traveled by the magnetic suspension train, and then compares the distance and the real-time speed with the traveling route of the magnetic suspension train to obtain the position of the magnetic suspension train.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, but rather as the subject matter of the invention is to be construed in all aspects and equivalents thereof.