Abstract : With the continuous development of lighting, lighting control systems have evolved from traditional control methods to intelligent control systems. This paper analyzes the control principles of various control systems, focusing on intelligent lighting control systems. It analyzes the characteristics of centralized and distributed intelligent lighting control systems and finally predicts that intelligent lighting will inevitably replace ordinary lighting. Keywords : Illuminate control system, Intelligent lighting 1 Introduction In today's world of economic globalization and regional economic integration, with the rapid development of the information and computer industries and the rapid improvement of people's material and spiritual living standards, people have increasingly higher demands for the flexibility, efficiency, and comfort of their work and living environments. Traditional work and living environments have faced strong challenges, leading to the emergence of intelligent buildings, intelligent communities, and intelligent homes. Various automation systems, such as building automation (BA), communication automation (CA), office automation (OA), and home automation (HA), are constantly appearing. People's requirements for lighting are also increasing, and traditional lighting technology has been strongly impacted by the times. Modern lighting technology has undergone profound changes, and "intelligent lighting" technology has emerged and rapidly developed, becoming an important trend in lighting technology development. 2. Traditional Lighting Control Methods Lighting control can be divided into switching control and dimming control. Dimming control includes continuous dimming control (the luminous flux of the controlled light source can be continuously changed) and discontinuous dimming control (the luminous flux of the controlled light source can only change between several fixed preset values). According to the principle of light emission, lighting sources can generally be divided into thermal radiation sources and gas discharge sources, with incandescent lamps and fluorescent lamps being typical examples. Thermal radiation light sources are those that use electrical energy to heat objects to incandescence, thus emitting light. Gas discharge light sources are those that use the discharge of gas or vapor to emit light. For thermal radiation light sources, both on/off control and dimming control are possible; simply adjusting the supply voltage to the light source regulates the luminous flux output. However, dimming control for gas discharge light sources is not so simple. It's not as straightforward as just controlling the supply voltage. These light sources all have ballasts; the 220V power frequency voltage is rectified before supplying the light source. To achieve dimming control, a matching ballast adapted to the specific gas discharge light source must be developed. The luminous flux output of the light source is adjusted by controlling the frequency and voltage of the ballast's output voltage. Since Edison invented the first light bulb, traditional lighting control methods have existed, primarily relying on manual control. Common methods include: First, using switches (protective switches or manual switches in the power distribution circuit) to control the on/off state of the power distribution circuit, thus achieving lighting switch control; Second, using manual knobs (traditional dimming control cabinets and lighting control consoles) in the lighting distribution circuit to adjust the electrical parameters of the power supply circuit (mainly voltage, current, frequency, etc.), thus achieving brightness adjustment of the lights, i.e., dimming control (its principle is shown in Figure 1). [align=center]Figure 1 Schematic diagram of traditional lighting control methods[/align] Traditional methods are simple, effective, and intuitive for lighting control. However, they rely too heavily on the individual ability of the controller, resulting in relatively decentralized control and ineffective management, with low real-time performance and automation. 3 Automatic Lighting Control Methods This control method uses digital control technology to remotely control the switching of lights. Typically, the control center sends a signal, which is then used by a Direct Digital Controller (DDC) to control the opening and closing of AC contactors in the power distribution circuit, thereby controlling the on/off state of the power distribution circuit and achieving lighting switch control. This approach solves the problems of relatively decentralized control and ineffective management in traditional methods, achieving automation of lighting control but failing to implement dimming control. Its control principle is shown in Figure 2. [align=center]Figure 2 Automatic Lighting Control Method[/align] Compared to traditional lighting control, the main problem solved by automatic lighting control is centralized control, resulting in a relatively higher degree of automation. However, due to the inherent technical characteristics of the DDC system, it exhibits significant shortcomings in lighting control systems. It not only cannot achieve dimming control but also struggles to implement functions such as pre-setting and scene management for lighting scenes. The main advantage of the DDC system is its ease of control calculation and judgment based on the overall situation, allowing for unified scheduling in the selection of control methods and control times. Its disadvantage is the high requirements placed on the controller itself, requiring sufficient processing power and extremely high reliability. As the system workload increases, the controller's efficiency and reliability will drastically decrease. Although Distributed Control Systems (DCS) are gradually replacing DDC systems and have achieved decentralized control and centralized management functions, the underlying devices still rely on traditional DDC technology. Only by applying fieldbus technology to field device-level management can this problem be fundamentally solved. 4. Intelligent Lighting Control System The 21st century is a networked era. With the continuous improvement of digital control technology, networked management is gradually permeating various traditional control systems. Since the beginning of the 20th century, as people's living standards have improved, their requirements for lighting have also changed significantly. Especially in some mid-to-high-end buildings, lighting is no longer simply about satisfying visual brightness and darkness; it should possess multiple control schemes to make buildings more vibrant, artistic, and provide rich visual effects and aesthetics. In the early 1990s, intelligent buildings were no longer simply equated with automatic building equipment management. In some important areas of buildings, simple on/off control was no longer sufficient. People began to pursue diversified lighting control methods to create environments with various artistic effects. Intelligent lighting control eliminates the reliance on automatic building equipment management systems for lighting control, truly achieving independent lighting control. This method not only controls on/off lights but also dims light sources. It is a control system integrating multiple lighting control methods, modern digital control technology, and network technology. Its emergence and development have simplified lighting control and maintenance management and provided a variety of artistic effects for architectural lighting. Intelligent lighting control systems are becoming increasingly widely accepted and used, leading to a proliferation of such products and manufacturers. Proper lighting control is an effective means of achieving both artistic and comfortable lighting, and a crucial measure for energy conservation. Green lighting refers to lighting products that are highly efficient, long-lasting, energy-saving, low-noise, low-harmonic, and low-electromagnetic-interference. In lighting design, the rational and correct selection of lighting control methods is not only a good balance between economy and practicality, but also a vital link in achieving "green lighting." Currently, intelligent lighting control systems researched and developed both domestically and internationally can be categorized by communication medium, including bus-type, power line carrier-type, and wireless network-type systems. Based on network topology, they can be classified as centralized or distributed. Centralized intelligent lighting control systems primarily use a star topology, a radial interconnection structure with a central control node connecting several peripheral nodes. Each lighting controller, control panel, and other device is connected to the central controller (CPU), which transmits data packets to the lighting controllers and other end-effector units, as shown in Figure 3. The advantages of this system include: high lighting control functionality, simple fault diagnosis and troubleshooting, simple access protocol, and high transmission rate. Its disadvantages are: due to excessive reliance on the central controller, the system's reliability and economy are relatively low. Although various improvement measures can enhance the reliability of the central controller and the system, its price disadvantage remains significant. [align=center]Figure 3 Centralized Intelligent Lighting Control System[/align] Distributed intelligent lighting control system is centered on central monitoring, forming a control backbone network and multiple control subnets. Each lighting controller, control panel, and other device has a central processing unit (CPU), and each controller and panel can be directly connected to the subnet. The system distributes the control functions of the original control center to control devices closer to the end, using an access control strategy to determine the order of information transmission between the devices and the monitoring center. Its structure is shown in Figure 4. [align=center]Figure 4 Distributed Intelligent Lighting Control System[/align] To build a distributed intelligent lighting control system, lighting controllers and panels are generally connected via a fieldbus to form a fieldbus subnet. By treating switches or control boxes in lighting circuits as network nodes in a fieldbus, and then forming a network through this fieldbus hub, all control signals, light switch status signals, and collected electrical signals communicate via the fieldbus network. This allows each node in the network to receive information from other nodes, facilitating easy monitoring and control between nodes. This allows for independent operation without a central monitoring host, and also solves the drawbacks of point-to-point connections where each control variable is connected by a separate wire at the field device level. The fieldbus control system uses a bus connection method instead of one-to-one wiring, reducing unreliability factors caused by connection points. Simultaneously, the system has online fault diagnosis, alarm, and recording functions for field-level devices, and can perform parameter setting and modification of remote devices, enhancing system maintainability. The fieldbus network system has excellent system scalability, allowing for easy addition of network nodes, such as sound detection, illuminance detection, image acquisition, and infrared signal acquisition nodes. These sensor nodes collect environmental parameters related to human activities, upload them to the central monitoring host for analysis, processing, and calculation, and make various control decisions to achieve intelligent management, better meeting the information integration requirements of intelligent buildings. Fieldbus is a digital communication network that enables the transmission of equipment status, fault, and parameter information. Replacing traditional control cables with fieldbus networks significantly reduces cable laying costs and lowers system and project costs. A fieldbus control system is both an open communication network and a fully distributed control system. It transforms individual, dispersed measurement and control devices into network nodes, connecting them via the fieldbus to form a network system and measurement and control system capable of communicating information and collaboratively completing automated control tasks. Therefore, researching intelligent measurement and control nodes based on fieldbus technology has become a key focus in the study of new measurement and control technologies and developments. Because fieldbus adapts to the trend of industrial control systems towards decentralization, networking, and intelligence, it has become a global hot topic in industrial automation technology since its inception, attracting widespread attention worldwide. The emergence of fieldbus has led to significant changes in the architecture and functional structure of currently manufactured automation instruments, distributed control systems, and programmable logic controllers. Manufacturers of automation equipment are forced to face another challenge in product upgrading. Therefore, research on intelligent measurement and control nodes is both a study of advanced technology applications and a necessity for market development. The most widely used technology in lighting control is LonWorks fieldbus. LonWorks (Local Operating Networks), or LON for short, marks a new era in networked control systems. LonWorks is a complete, fully open, interoperable, mature, and low-cost distributed control network technology, and many manufacturers and users have adopted LonWorks technology in their control network solutions. Lighting control systems based on LonWorks intelligent nodes mainly use Neuron chips as intelligent control nodes to control various subordinate execution units. The overall structure diagram of the control system is shown in Figure 5. [align=center] Figure 5 Overall System Structure[/align] The Neuron chip intelligent node can collect and process field data, and can also connect to other control nodes through transmission lines to communicate with the host computer, enabling scalability. The Neuron intelligent node constituting the LonWorks control network consists of a neuron chip, sensors, control devices, transceivers, and power supplies, as shown in Figure 6. The main functions of each part are as follows: (1) Neuron chip: controls the input and output of field data, information processing, and can also realize communication with LonWorks network. (2) I/O interface: the measurement circuit is mainly responsible for collecting field data, the control circuit transmits control commands to the execution unit, and when the upper-end command is transmitted to the control circuit, the control circuit is responsible for turning on or off the corresponding lamp object. (3) Other circuits: the control system also includes a crystal oscillator circuit to provide the working clock for the neuron chip. The reset circuit can prevent the neuron chip from working below the minimum working voltage. [align=center] Figure 6 System structure block diagram[/align] 5 Conclusion Green lighting has been officially included in the national plan, and the concept of prioritizing terminal energy saving has been deeply rooted in people's hearts; intelligent lighting control is an effective means to save energy consumption, improve property management level, reflect modern lifestyle and optimize working environment. In the near future, intelligent lighting will replace ordinary lighting, and its various advantages will be fully reflected. References [1] Chen Tao, Mao Xinwei. Engineering application of intelligent lighting control system [J]. Intelligent Electrical, 2004 (11): 69-71. [2] Wang Wensheng. Intelligent lighting control and energy saving [J]. Intelligent Building and Urban Information, 2005 (4): 120-122. [3] Qiu Jiping. Analysis and discussion of intelligent lighting control system based on fieldbus [J]. Low Voltage Electrical Appliances, 2005 (7): 19-26. Detailed contact information of the author Name: Liu Junhua Work unit: School of Electrical Engineering, Southwest Jiaotong University Mailing address: P.O. Box 241, Jiuli Campus, Southwest Jiaotong University, Chengdu, Sichuan Province Postcode: 610031 Telephone Fax: 13880604672 E-mail: [email protected] [email protected] Author's resume: Liu Junhua (1982-), male, from Yongzhou, Hunan Province, Master's degree, major research direction: control theory and its application. Ye Feng (1982–), male, from Wuhan, Hubei Province, holds a master's degree and his main research area is fieldbus control systems.