Semi-active RFID technology-based parking space detection, reverse car search, and intelligent guidance system
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1 Introduction
1.1 Document construction instructions
The purpose of this program is to let integrators, engineering companies and users understand the design concepts, principles, overall planning and how to play a huge role in the field of intelligent parking lot management of the Internet of Things RFID technology, and elaborate on the working principles and installation of related Internet of Things equipment. Location and other information so that integrators, engineers, and users can correctly understand the revolutionary changes brought about by the field of smart parking with the focus of the Internet of Things in smart transportation, and establish a correct understanding of the Internet of Things in the field of smart parking. If you encounter any confusion or confusion during the reading process, please contact the program writer.
Explanation of terms and abbreviations
Term explanation
RFIDRadio frequency identification is a communication technology that can identify specific targets and read and write related data through radio signals without the need to establish mechanical or optical contact between the identification system and specific targets
The dual-frequency semi-active electronic tag tag has been in a dormant state before entering the working state. When the tag enters the reading area of the reader, it is excited by the radio frequency signal from the activator and enters the working state
The low-frequency activator is in real-time addressing state, real-time “actively” detects the surrounding active electronic tags, and sends its own ID code and antenna ID number to the active electronic tag receiving module
The omnidirectional reader receives and demodulates the radio frequency signal sent by the electronic tag
Intelligent parking lot management system performs parking space detection, the map displays real-time parking lot vehicle information, and performs vehicle identification
2. Project background
2.1 Status analysis
With the development of social economy and the improvement of people’s living standards, more and more cars have entered the family, and the era of car consumption has quietly arrived. With the increase of vehicles, the gap of urban parking spaces is getting bigger and bigger, and the construction of parking lots needs to keep up. For important public places, the parking lot is an important supporting facility, which directly affects its service quality and positioning level. And the amount of operating income.
In order to improve the service level of the parking lot, the parking lot intelligent management system is indispensable. It has already played an important role in most parking lots, bringing convenience to people’s parking, but also has good social and economic benefits.
In the intelligent parking lot management, it involves various aspects of management. The management and charging of vehicles entering and exiting, the detection and intelligent guidance of vehicles entering and exiting the parking lot, and the reverse car search are several important aspects. Each subsystem interacts with each other. Association, coordinated operation.
The entrance and exit management system requires strict real-time management of various vehicles, strict records of their time of entry and exit, identification and registration of various vehicles, and input of various information into the database. Effectively and accurately monitor and manage all vehicles at entrances and exits.
The parking space intelligent guidance system is to help car owners find suitable parking lots and parking spaces in the shortest possible time, avoiding that vehicles cannot find the parking lot, cannot find a parking space after entering the parking lot, or even grab each other’s parking spaces, which leads to congestion, improves operational efficiency, and makes Drivers feel good service and pleasant feelings.
The intelligent reverse car search system is when the car owner returns to the parking lot, because the parking lot is too large or the terrain is not familiar, the car owner is easy to find the car. The system can help the car owner find the area where the car is parked as soon as possible, improve the owner’s satisfaction, and speed up The vehicle turnover of the parking lot improves the utilization rate and income.
Establish a set of intelligent parking lot entry and exit management, parking space detection, intelligent guidance and reverse car-finding system to make the parking service safe, simple and accurate, and to control the cost and operating cost in an appropriate range, which is the current parking lot Trends in management. It can solve all the drawbacks of manual management while improving efficiency. It is an ideal model for parking lot management.
2.2 Significance of system construction
1. The construction of smart parking lots is an important part of the city’s smart transportation. Building a smart parking lot management system can alleviate traffic congestion in the city, enhance road traffic capacity, and reduce vehicle transportation costs. In turn, we can better build smart transportation and serve smart cities.
2. For a long time, the construction of parking facilities in large and medium-sized cities lags behind the rapid growth of motor vehicles, resulting in more prominent and serious parking contradictions, resulting in “difficult parking, random parking” has also become a difficult and hot spot in urban traffic management, creating smart parking Site construction can completely solve the phenomenon of “difficult parking and random parking”
3. In general, the construction of smart parking lots can improve the operating efficiency of the parking lot, make parking and finding cars more convenient and quick, and improve the overall service level of the parking lot.
3. System Overview
3.1 System design principles
Focus on overall planning
The intelligent parking lot management system (semi-active RFID technology parking lot entrance and exit management, parking space detection, reverse car search, intelligent guidance system) consists of three parts. First, the core hardware of the intelligent parking lot management system (including: 2.4G +125k dual-frequency semi-active electronic tags, 125k low-frequency activators, omnidirectional readers) Second, the intelligent parking lot management system platform (including automatic identification of entry and exit systems without parking at entrances and exits, parking space detection systems, intelligent parking space guidance and counter To find the car system); third, hardware middleware (including PLC, LED dynamic display guide screen, query machine, industrial-grade switch, cabinet, PC, server, uninterruptible power supply, etc.);
Based on independent research and development
The core technology of the system construction is 2.4G+125K dual frequency bands. All the core equipment provided by the company has completely independent intellectual property rights. 2.4G micro-power technology, 125K low-frequency precise boundary control, low-frequency wake-up technology, automatic identification of parking vehicles And non-contact information collection and processing, the advanced information technology, data communication technology, electronic control technology and computer processing technology are effectively integrated into the parking lot management system, so as to establish a system of various systems and play a full role. And an intelligent management system platform that runs real-time, accurately and efficiently.
Focus on future development
In terms of overall system architecture, service equipment selection, dual-frequency semi-active electronic tag function selection, basic data collection, etc., fully consider the realization of subsequent functions, taking into account the compatibility of equipment, system scalability, and function scalability And the diversity of applications;
Strengthen system specifications
System development and resource construction conform to a unified technical specification and characterization system, pay attention to the continuity and sharing of development work, and pay attention to leaving standardized data and control interfaces for subsequent system development and promotion. Unified development of technical indicators such as application technology, data storage format, signal transmission system, and interconnection interface mode;
Utilize construction benefits
System development and construction should combine the actual conditions of the parking lot, and further strengthen the traffic management on the basis of the existing system; follow the overall planning, construction while using, and gradually improve the construction ideas to give full play to the construction benefits;
3.2 The working principle of the system
The intelligent parking lot management system consists of automatic entry and exit recognition of vehicles at entrances and exits, parking space detection and positioning, intelligent guidance and reverse car-finding subsystems. When vehicles enter and exit the parking lot, the low-frequency coils buried in the entrance and exit activate the Dual-frequency electronic tags, the tags actively send the tag ID and coil address code, which are read by a remote 2.4G card reader, connected to the controller, and control the opening and closing of the gate to achieve non-stop access management.
The intelligent vehicle guidance system provides data for parking space guidance according to the real-time status of parking spaces provided by the parking space detection system, and sends the data to the main controller and management computer in real time through the data collector and node controller, and the main controller updates each intersection in time The number of empty cars on the guide screen guides customers to park. At the same time, the parking indicator is controlled to display different colors according to the usage of the parking space. Red is occupied and green is vacant. Customers can see it from 50 meters away. According to the color of the parking indicator, customers can quickly find a parking space.
The reverse car search system detects and locates the parking space according to the dual-frequency electronic tags on the vehicle. Under the premise of vehicle positioning, the system records the location information of the vehicle. When returning to the parking lot to search for the car, the customer queries the vehicle. The operation of the location is simpler. Just find a query terminal nearby and directly read the ID representing the identity of the vehicle for query. The parking space information corresponding to the voucher will be displayed on the display screen, such as “B1 floor, A08 zone”. You can quickly guide the guests from a huge blank space to a relatively small area. In this small area, for most guests, finding their own car is no longer a problem. This is achieved The intelligent process to help guests find a car. It can also be combined with the built-in electronic map in the query terminal to automatically generate a road map in real time to help customers find their vehicles easily and quickly.
3.3 Schematic diagram of overall system design
3.4 System function introduction
In the intelligent parking lot management, it involves all aspects of management. The management of vehicle entry and exit and charging, parking space detection and positioning, intelligent parking space guidance and reverse car search system are several important aspects. Each subsystem interacts with each other. Association, coordinated operation.
The entrance and exit management system requires strict real-time management of various vehicles, strict records of their time of entry and exit, identification and registration of various vehicles, and input of various information into the database. Effectively and accurately monitor and manage all vehicles at entrances and exits. For fixed vehicles and VIP vehicles, automatic identification of entry and exit without stopping is realized.
The intelligent parking guidance system is to help customers and vehicles find suitable parking lots and parking spaces in the shortest possible time, avoiding that vehicles cannot find the parking lot, cannot find the parking space after entering the parking lot, or even grab each other’s parking spaces, leading to congestion and improving operational efficiency , So that the driver feels good service and pleasant feelings.
The intelligent reverse car search system is when the car owner returns to the parking lot, because the parking lot is too large or the terrain is not familiar, the car owner is easy to find the car. The system can help the car owner find the area where the car is parked as soon as possible, improve the owner’s satisfaction, and speed up The vehicle turnover of the parking lot improves the utilization rate and income.
3.5 System software introduction
4. Overall system construction plan
The design of an intelligent parking lot management system based on semi-active RFID technology includes a vehicle entrance and exit management system, an intelligent parking guidance system, and an intelligent reverse car-finding system. Each system is related to each other and operates in coordination. Jointly build the intelligent and informatization of parking lot management.
Below we will explain in detail several components of the intelligent parking management system based on semi-active RFID technology.
4.1 Schematic diagram of the overall architecture of the vehicle entrance and exit management system
Semi-active RFID technology is used to create a parking lot entrance and exit management system. Dual-frequency (2.4G+125K) electronic tags are installed on the vehicles, low-frequency induction coils are buried at the entrances and exits, and 2.4G active card readers are installed. The electronic tags are usually in a dormant state. When entering and exiting the parking lot, it is activated by the low-frequency activator induction coil in the entrance and exit lanes. The low-frequency chip on the label will analyze the 125K activator coil ID and the RSSI field strength value of the low-frequency signal in real time, and then conduct a strong signal transmission in the 2.4G frequency band ( The wirelessly transmitted data packet contains the tag ID, the activator coil ID and the low-frequency field strength RSSI value). After the 2.4G card reader receives the tag ID and the activator coil ID, it sends the signal to the controller via Wiegand 26, relay or RS485 output to control the opening and closing of the gate. On the one hand, it is possible to enter and exit the parking lot without stopping, improve the efficiency of vehicles passing through the entrance and exit, reduce traffic jams, and on the other hand eliminate the problem of car following.
4.1.1 The hardware composition of the vehicle entrance and exit management system
1) RFID card reader, for parking 2.4G signal coverage, reading the dual-frequency electronic tag information on the vehicle, and connecting through the serial port 485, RJ45, Wiegand 26, relay output and controller to control the opening and closing of the gate closure.
2) The low-frequency activator is installed on the ground of the vehicle entrance and exit. The activator activates and wakes up the dual-frequency electronic tag, resolves the ID of the induction coil and the electronic tag, and transmits the signal in the 2.4G frequency band.Reader for reading
3) The dual-frequency electronic tag is placed on the vehicles entering and exiting the parking lot to identify the vehicle. For entering and exiting the parking lot, parking space detection and intelligent guidance and reverse car search services are performed.
4.1.2 Precautions for the installation of various hardware of the vehicle entrance and exit management system
1) The low-frequency activator adopts induction coils and is installed in a groove buried in the ground. The ground is cut to 20 cm and buried to form a loop. The antenna needs to be protected by a PVC pipe to prevent water ingress from corroding the antenna.
2) Dual-frequency electronic tags are placed on vehicles entering and exiting the parking lot to identify the vehicles. For entering and exiting the parking lot, parking space detection and intelligent guidance and reverse car search services are performed.
3) The 2.4G card reader performs full coverage of the signal, receives the data sent by the tag in real time, and installs it at the entrance and exit of the vehicle, about 1.5M above the ground, to ensure that it can cover the area of the low-frequency activator coil antenna to ensure the data Read
4.2 Schematic diagram of the overall architecture of the parking space intelligent guidance system
Parking space detection and positioning system
Schematic diagram of the overall architecture of parking space detection
Parking space detection and positioning management software
The low-frequency activator has 4 to 6 rod antennas. According to the size of the parking space, a rod antenna is installed on the zebra crossing of each parking lot. A low-frequency activator can locate up to 5 parking spaces. A dual-frequency electronic tag is placed on the vehicle. , The activator radius of a rod antenna is about 4M. The low-frequency activator antenna adopts a cyclic activation and cyclical wake-up mechanism. When the vehicle is parked in the No. 1 parking space, it is first activated by 3001 and then activated by 3002 to activate the tag’s At the same time, the RSSI value (signal strength value) of each antenna is displayed at the same time. When the RSSI value of the 3001 antenna and the 3002 antenna are the largest in parking space No. 1, it is detected that the vehicle is parked on the parking space No. 1.
The parking space detection and positioning system detects in real time whether there are vehicles parked in the parking space, and sends the data to the main controller and management computer in real time through the data collector and node controller. The main controller updates the number of empty cars on the guidance screen of each intersection in time. Instruct customers to stop. At the same time, the parking indicator is controlled to display different colors according to the usage of the parking space. Red is occupied and green is vacant. Customers can see it from 50 meters away. According to the color of the parking indicator, customers can quickly find a parking space. The information display system dynamically displays the number of parking spaces in the parking lot in real time. The main entrance guide screen displays the number of empty cars in the entire parking lot, the location guide screen displays the number of empty cars in the area, and the intersection guide screen shows the number of empty cars in the driving direction. The parking space information is released by the main controller in real time.
4.2.1 Hardware composition of parking space intelligent guidance system
1) RFID omnidirectional reader, to achieve 2.4G information coverage in the entire parking area, to ensure that the data actively sent by the tag can be read in real time, and transmitted to the background through the RJ45 network cable for data processing.
2) The low-frequency activator (parking space detector) adopts RFID technology, and one low-frequency activator can detect and locate 5 parking spaces at most
3) Dual-frequency electronic tags, placed on the vehicles that need to be managed and identified
4) Parking space indicator, ultra-high brightness LED indicator, red and green indicator, red light means occupied, green light means vacant space
5) Controllers are divided into main controllers, node controllers, regional controllers, and main controllers are the core control equipment of the intelligent guidance system, which completes the collection of all system data and the issuance of control instructions, and manages and controls all equipment in the system. Can connect 1-16 node controllers. Node controller, data acquisition equipment, the design capacity is 1-32 RS485 equipment, it is recommended to connect about 16 in the actual project, and one equipment box can contain 2 sets.The area controller is a data acquisition device with a design capacity of 1-32 RS485 devices. It is recommended to connect about 16 in the actual project, and one device box can contain 2 sets
6) The parking space guide screen is divided into the main guide screen and the parking space guide screen. The main entrance guide screen displays the number of empty parking spaces on each floor and is installed on the ground. The waterproof and moisture-proof parking space display uses ultra-high brightness outdoor LEDs, which can be clearly identified by direct sunlight. Parking space guide screen, hoisted above the indoor passage, waterproof and moisture-proof, the remaining number of parking spaces is displayed using yellow and green LEDs, which are clearly identifiable at 50 meters
4.2.2 Precautions for the hardware installation of the parking space intelligent guidance system
1) RFID omnidirectional readers achieve full coverage of 2.4G signals in the parking lot. The indoor identification distance of 2.4G omnidirectional readers is about 60m. The number of omnidirectional readers is arranged according to the parking lot area. Pay attention to the installation height of the omnidirectional reader (usually 3 to 4m), and the waterproof connector (power connector, network connector)
2) The low-frequency activator is also called the parking space detection locator. According to the number of parking spaces, each rod antenna of the activator is shallowly buried on the zebra dividing line of each parking space.
3) Place the dual-frequency electronic tag on the vehicle and try to place it on the front windshield
4.3 Schematic diagram of the overall architecture of the intelligent reverse car search system
The establishment of the intelligent reverse car-finding system is realized on the basis of detecting and positioning parking spaces. Under the premise of realizing precise positioning of the vehicle, the system record contains the location information of the vehicle. When returning to the parking lot to find the vehicle, it is easier for guests to query the location of the vehicle. They only need to find a query terminal nearby and read it directly. The electronic tag that represents the identity of the vehicle, enter the tag ID number for query, and the parking space information corresponding to the electronic tag will be displayed on the display screen, such as “B1 floor, A08 zone”.At the same time, the route information is automatically generated in the form of an electronic map, and the owner can find the vehicle according to the provided route
The query terminal is generally set up on the passageway where guests enter the parking lot on foot, or on the only way near the central toll office, so that guests can make inquiries in advance and find out according to the map before entering the parking lot to find a car.
The query terminal can also be combined with the commercial multimedia information query machine, which is more widely and abundantly used.
4.3.1 The hardware composition of the intelligent reverse car search system
1) RFID omnidirectional reader, to achieve 2.4G information coverage in the entire parking area, to ensure that the data actively sent by the tag can be read in real time, and transmitted to the background through the RJ45 network cable for data processing.
2) The low-frequency activator (parking space detector) adopts RFID technology, and one low-frequency activator can detect and locate 5 parking spaces at most
3) Dual-frequency electronic tags, placed on the vehicles that need to be managed and identified
4) Electronic map type query terminal, the query machine has a display screen, prompts parking location and current location, automatically generates route, uses electronic map to self-read card to query vehicle location, intuitive and clear
4.3.2 Precautions for the hardware installation of the intelligent reverse car search system
1) RFID omnidirectional readers achieve full coverage of 2.4G signals in the parking lot. The indoor identification distance of 2.4G omnidirectional readers is about 60m. The number of omnidirectional readers is arranged according to the parking lot area. Pay attention to the installation height of the omnidirectional reader (usually 3 to 4m), and the waterproof connector (power connector, network connector)
2) The low-frequency activator is also called the parking space detection locator. According to the number of parking spaces, each rod antenna of the activator is shallowly buried on the zebra dividing line of each parking space.
3) Place the dual-frequency electronic tag on the vehicle and try to place it on the front windshield
4) The electronic map query terminal is placed in the elevator room on each floor. The elevator entrance is the place where the departing guests must go. The location of this location can maximize the coverage of the guests, and also shorten the process and time of the guest inquiries.
5. Project implementation
5.1 Project implementation process
Project implementation process
5.2 Project after-sales service
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