The solution design of the electronic stop sign system based on the on-board electronic label
chrispeng [ad_1]
Electronic stop sign refers to the electronic stop sign system, including three main parts: vehicle location information acquisition, information communication and display.Electronic bus stop signs currently being piloted in some large and medium-sized cities[1-3], All obtain vehicle location information through GPS, communicate through GSM short message, and display through LCD or LED. When working, the vehicle-mounted GPS receiver obtains the vehicle location coordinate information by receiving satellite signals, and sends it to the mobile operator’s GSM short messaging center through short messages, and the short messaging center transmits it to the vehicle dispatching center through a dedicated line for processing , Get the distance information of the vehicle (distance to the downstream station and required time, etc.), the distance information is transmitted back to the GSM short message sending and receiving center from the dispatching center, and finally sent from the GSM short message sending and receiving center to the electronic station of the downstream station The brand is displayed on the LCD. The existing electronic station signs mainly have the following two drawbacks: (1) The early construction cost is high. Although the price of vehicle-mounted GPS receivers is not high, it will require a huge investment of funds if it is fully promoted on the city’s buses; (2) The later operating costs are high. The high operating cost is mainly caused by the GSM short message communication. In order to improve the positioning accuracy, the vehicle needs to perform a positioning (receive a satellite signal once) every few seconds to tens of seconds, and send a short message to the GSM transceiver center. The GSM transceiver center must send the distance station information of each vehicle to the electronic stop sign, that is, each vehicle needs to send two short messages for each positioning (one sent by the vehicle to the GSM center, and the other sent by the GSM center to the downstream Station electronic station sign), so the number of short messages is very huge. Although the unit price of each short message is not high, the communication cost caused by such a huge amount of short messages is beyond the reach of the bus company. If it is passed on to consumers, consumers will not accept it. Therefore, this kind of electronic stop sign is currently only used as a pilot on certain lines, and it is difficult to promote and apply. This article proposes a new electronic stop sign solution, which reduces the initial construction cost by using on-board electronic tags (RFID) instead of on-board GPS receivers, and uses power lines to transmit vehicle location information instead of GSM short messages, which reduces communication costs. .
1 System composition
The block diagram of the electronic stop sign system described in this article is shown in Figure 1. It is mainly composed of the station device at the station, the electronic tag installed or attached to the car, the power line and the dispatching center.
The station device is the core part of the electronic stop sign system. As shown in Figure 2, it is mainly composed of a tag reader, a power carrier transmitter, a power carrier receiver, a main controller (MCU), and an LED parking indicator screen. The electronic tag is installed/affixed to the bus, and the vehicle code information (the code representation of a certain road and a certain number of cars) is pre-stored in the electronic label.
The tag reader is used to read the vehicle code information carried by the electronic tag of the arriving vehicle. The power carrier transmitter modulates the digital signal that needs to be transmitted to the next station and then couples it into the power line for transmission. The power carrier receiver demodulates the received modulated signal (from the upstream station) and restores it to a digital signal.
The main controller (MCU) mainly completes the processing, storage, transmission and control of vehicle coding information. The main controller obtains the code information of the arriving vehicle from the tag reader, and obtains its number after processing (that is, a certain number of vehicles on a certain road). On the one hand, it is displayed on the LED parking indicator screen of the station, and the station is added at the same time. The station is coded and sent to the next station by the transmitter. At the same time, the main controller also obtains the station code and vehicle code information from the upstream station from the power carrier receiver, so that it knows that a certain road and a certain car has arrived at a certain station. In addition to displaying it on the display of the station, it is handed over to The power carrier transmitter transmits to the next station.
The LED parking space indicator screen is shown in Figure 3, including the LED lamp group and the screen substrate. The station name, scale line, kilometers and time minutes are printed on the screen substrate. The station name is aligned with a certain scale line, and the number of kilometers from the station to the departure station and the travel time of the bus are marked above the scale line. The length of the bus line, the location of the station, and the time required for vehicle operation are all fixed (normal conditions), so the distance of each station along the line from the departure station and the required travel time can be marked on the scale line. One LED is installed on each scale line, and several LEDs are arranged between the two scale lines. When the bus arrives at a certain station, the LED on the scale line corresponding to the station is turned on, and when leaving the station, the LED on the corresponding scale line is turned off, and the scale line of this station and the next nearest station are successively lit according to the historical travel time. Correspond to the LED between the scale lines.
Through the LED parking indicator screen, passengers can know the location of the bus along the line, the distance from the station and the time of arrival at the station at any time. If you can’t arrive within the predetermined time, there must be a blockage, and you can also know the location of the blockage. From the received car code and station code information, the dispatch center can know where a certain road or a certain number of vehicles is currently located at a certain station or between which two stations, and where it should arrive at the next moment. If it cannot arrive within the expected time, Knowing that the car is blocked, dispatching arrangements will be made according to the situation. This information can be visually displayed through the LED parking indicator screen or PC.
[ad_2]
