Abstract: To overcome the shortcomings of traditional elevator safety management and maintenance methods, this paper proposes to establish an elevator safety monitoring system based on Internet of Things (IoT) technology. The system architecture consists of a perception layer, a convergence layer, and a transmission and application layer. The hardware adopts a modular design approach, with separate modules for central control, data acquisition, GPRS, radio frequency processing, and power supply. The software is designed with modules for basic information, maintenance information, monitoring information, and data analysis. This establishes an elevator safety monitoring and management system that automates and informatizes elevator management. Its application and promotion have broad social and economic benefits.
Keywords: elevator safety, modular design, monitoring system
0 Introduction
Elevators, as a form of public transportation, are now widely used in high-rise residential buildings, large shopping malls, office buildings, and other public places. For a long time, elevator accidents in my country have resulted in numerous injuries and fatalities, with an accident rate and severity far exceeding those in developed countries and regions. As a special type of equipment closely related to public safety, elevator safety is receiving increasing attention from the government and society. As of 2013, my country had over 2 million elevators, growing at a rate of approximately 20% annually. However, the existing number of inspection personnel is insufficient to meet the needs of elevator malfunction handling and regular maintenance. Safety component failures, missed inspections, and inadequate maintenance are frequent occurrences. Furthermore, the existing regulatory system is still imperfect, and management and maintenance levels are lacking. Ensuring elevator safety, minimizing losses, and providing a safe living environment for the public has become a top priority for city managers. Traditional elevator management and maintenance methods are far from meeting current needs. Applying emerging Internet of Things (IoT) technology to elevator monitoring to achieve automated and information-based elevator safety monitoring and management is imperative.
The Internet of Things (IoT) is built upon the computer internet, utilizing technologies such as RFID, advanced sensors, and wireless data communication to construct a network covering various objects worldwide. Within this network, objects can "communicate" with each other without human intervention. Essentially, it uses radio frequency identification (RFID) technology to achieve automatic identification of objects and the interconnection and sharing of information via the computer internet. Managers can use computers or mobile phones to intelligently identify, locate, track, monitor, and manage objects.
An elevator safety monitoring system based on Internet of Things (IoT) technology collects various monitoring parameters in real time through a sensor network and transmits them to a monitoring platform via wireless or wired networks, thereby enabling intelligent management and maintenance of elevators. In this management model, the operating status of elevators can be monitored in real time, and status information can be sent to the elevator safety management and monitoring center via the network, facilitating timely information interaction and processing between people and elevators. Establishing an elevator safety monitoring system enables real-time monitoring of elevator status, provides early warnings and alarms for malfunctions, reduces the incidence of elevator failures, and improves the speed of repairing faulty elevators. Furthermore, it provides technical support for timely and accurate elevator maintenance.
1 System Design Overall Scheme
The elevator safety monitoring system primarily monitors multiple characteristic parameters affecting the safe operation of elevators in real time. These parameters are then transmitted wirelessly to a computer monitoring and management system, which coordinates and manages the actual operating status and maintenance of the elevators. The elevator safety monitoring system is designed to consist of a sensing layer, a convergence layer, and a transmission and application layer, as shown in Figure 1.
Figure 1 System structure diagram
The sensing layer consists of various sensors installed around the elevator. The design principle is to ensure that sensor signals are independent of the elevator's internal operating signals, avoiding mutual interference. These sensor signals monitor the physical and environmental conditions at various locations within the elevator in real time, particularly key safety parameters. They can continuously transmit information to the convergence layer 24 hours a day. RFID detection points will be deployed at the elevator site, storing elevator installation, maintenance, and inspection information. This information provides the technical foundation for timely elevator maintenance.
The core of the aggregation layer is the aggregation substation. The aggregation substation organizes various information transmitted from the sensing layer, performs preliminary analysis on the data according to the requirements, and differentiates the analysis results. The processing results are classified according to the elevator operation status. In cases involving particularly serious threats to personal safety, alarm information is issued immediately. Other cases are stored locally and then sent to the application layer through the transmission layer for further processing.
The transmission layer primarily uses GPRS technology to transmit data to the application layer platform, leveraging the internet to enable management and maintenance by all relevant parties. The application layer platform is a management system for elevator safety monitoring, fault analysis, and maintenance records. One of its tasks is to receive real-time data transmitted from various aggregation substations and analyze elevator operation records over a specific time period to comprehensively understand the real-time operating status and fault distribution of elevators. It promptly and accurately transmits potential and existing faults to relevant units and individuals, and provides a query platform for property management departments, government regulatory departments, and maintenance units. A second task is to accurately record elevator installation, modification, maintenance, repair, and inspection operations, ensuring consistency between wireless transmission technology and information stored in on-site RFID tags, providing technical support for elevator maintenance queries and issuing early warning information.
2 System Hardware Design
The monitoring terminal of the elevator safety monitoring system hardware consists of a data acquisition module, a central control module, a display module, a GPRS communication module, an RFID electronic tag, and a power supply module, as shown in Figure 2. The monitoring terminal can collect signals from various sensors in real time, enabling 24/7 monitoring of the elevator's operating status and providing timely alarms for any safety hazards.
Figure 2 System Hardware Functional Modules
2.1 Central Control Module
The elevator safety monitoring system's monitoring terminal requires multiple I/O ports and related debugging interfaces. Considering future system expansion and upgrades, the central control unit of this system was designed with the STM32F103C8T6 processor. The STM32F103C8T6 uses a high-performance ARM Cortex-M3 32-bit RISC core with a frequency of 72MHz, 128KB of built-in flash memory and 20KB of SRAM, abundant enhanced I/O ports, and peripherals connected to two APB buses. Internally, it includes two 12-bit ADCs, three general-purpose 16-bit timers, and one PWM timer, as well as standard communication interfaces: two I2C and SPI interfaces, three US-ART interfaces, one USB interface, and one CAN interface. It also features low cost, low power consumption, excellent computing performance, and advanced interrupt system response, all of which fully meet the system design requirements.
2.2 Data Acquisition Module
The monitoring system's data acquisition module primarily collects real-time data on characteristics affecting elevator safety. These parameters are provided by sensors distributed at monitoring points throughout the elevator's critical components. The acquisition module design first requires signal conditioning of the sensor signals to convert them into suitable voltage signals. For some high-voltage signals, optocoupler isolation circuits are also necessary to improve the system's anti-interference capabilities.
2.3GPRS module
The monitoring terminal needs to transmit the monitored elevator operating status parameters to the remote monitoring system in real time via wireless transmission technology. Due to the packet-switched data transmission mode introduced by GPRS, the wireless data transmission rate can reach up to 170 kbit/s. GPRS also supports the most widely used TCO and IP protocols on the Internet, providing global wireless access to the Internet and other packet networks. Therefore, this system design utilizes GPRS technology to achieve wireless data transmission and control.
2.4 Radio Frequency Processing Module
The main functions of the radio frequency processing module are to generate high-frequency transmission energy, activate and power the electronic tag, modulate the transmission signal, transmit data to the electronic tag, and receive and demodulate the radio frequency signal from the electronic tag.
2.5 Power Module
This system is designed with a dual power supply method, using an external power adapter and a built-in lithium battery. The power adapter uses an industrial AC220V/DC12V module, which has strong anti-interference capabilities, a wide range of applications, meets national electromagnetic certification, is highly versatile, technologically mature, and cost-effective, and can meet the power requirements of elevator safety monitoring systems.
3 System Software Design
The system software design comprises two parts: the underlying monitoring terminal and the upper-level information management system. While the hardware design of the monitoring terminal was systematically studied previously, its software design is also crucial for achieving its intended functions. Due to space limitations, the details of the monitoring terminal's software design will not be elaborated upon here. The upper-level information management system software mainly includes a basic information management module, a monitoring information module, a maintenance information module, and a data analysis module. After collecting the data via a wireless transmission module, it undergoes centralized processing and then utilizes the internet for remote real-time monitoring, querying, and maintenance by regulatory departments, user units, and maintenance units.
3.1 Basic Information Module
This module manages basic elevator information and users. Basic elevator information includes elevator name, address, maintenance company name, maintenance personnel name, maintenance personnel contact information, elevator manufacturer, last maintenance date, next maintenance date, next annual inspection date, and inspection unit name. User management features include editing operator information such as name, password, and contact information; adding, deleting, and modifying the number of operators; setting operator access permissions; and implementing tiered and permission-based viewing modes, ensuring only authorized personnel can view information within their privileges.
3.2 Maintenance Information Module
The maintenance company has the authority to set up elevator data management, fault management, and maintenance management functions. Using the network, the maintenance company can view the status of the elevators under its management at any time, such as lists of elevators with faults, elevators awaiting maintenance, and elevators awaiting annual inspection. Furthermore, it can modify, supplement, and update relevant information about the elevators under its management, and choose to set relevant management restrictions. In terms of software design, browsing and querying are the main functions. Queries can be performed by "time range," "elevator brand," "maintenance company," "maintenance personnel," and "elevator name," etc. A user-friendly human-computer interface is designed for data and information updates to meet the system's functional requirements.
3.3 Monitoring Information Module
The monitoring information module is used to monitor the elevator's operating status and malfunctions in real time. The elevator safety monitoring center server, property management company, maintenance company, and supervising unit can all remotely and dynamically monitor the elevator's safety circuits, door lock circuits, up/down movement, door opening/closing status, and other safety-related characteristic parameters. The monitoring information module includes a fault SMS alarm function. When an elevator malfunctions, the module will immediately notify on-site personnel via SMS. If the relevant personnel fail to take action within a set time frame, the system will escalate the alarm and automatically send the fault information to higher-level supervisors and unit leaders.
3.4 Data Analysis Module
The data analysis of the elevator safety monitoring system comprises two parts: basic data analysis performed at the monitoring terminal and complex data analysis performed on the server. The monitoring terminal performs basic data analysis on the monitored data to generate elevator operating status data. It compares the elevator's operating status characteristic parameters with standard parameters to analyze and determine the current elevator operating condition and potential malfunctions. When the comparison result exceeds the standard parameter value range, the malfunction information is promptly sent to relevant management personnel via SMS. The server-side data analysis primarily involves feature extraction, principal component analysis, and trend prediction of the elevator operating status data over a period of time. This is accomplished using data processing and data mining techniques to achieve early warning of elevator malfunctions.
4 Conclusion
The completed elevator safety monitoring system based on IoT technology can monitor the actual operating status of elevators in real time, promptly provide alerts for faults and alarms, and classify alarm information according to severity. The system uses GPRS wireless transmission technology, eliminating the need for extensive on-site network cabling, simplifying installation and maintenance, and offering broad adaptability to any elevator model. The monitoring and management system automatically records elevator operating status data, provides early warnings based on data analysis, and automatically analyzes the causes of existing faults to help maintenance personnel resolve them promptly. Regulatory departments, user units, and maintenance units can all log in via the network for convenient supervision and management. Utilizing IoT technology to monitor the operating status of urban elevators and facilitate multi-party coordinated management of elevator management departments provides a scientific and effective method for urban elevator operation management. The IoT-based monitoring and management system completes related management work without on-site personnel, greatly facilitating elevator management. On the one hand, it improves work efficiency and management effectiveness, reduces the workload of maintenance personnel, and on the other hand, it maximizes elevator safety, resulting in broad social and economic benefits.
References
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About the Author
Wang Jianping, female, born in April 1974, works at the Xinjiang Uygur Autonomous Region Special Equipment Inspection and Research Institute, specializing in elevator inspection. She holds the professional title of engineer. Her mailing address is: Special Equipment Inspection and Research Institute, No. 188, Hebei East Road, Urumqi, Xinjiang, 830011, China.
Chen Fei, male, born in March 1979, works at the Xinjiang Uygur Autonomous Region Special Equipment Inspection and Research Institute, as the deputy director of the Elevator Inspection Institute II, and holds the title of senior engineer. His mailing address is: Special Equipment Inspection Institute, No. 188, Hebei East Road, Urumqi, Xinjiang, 830011, China.
