Lighting Control For Classroom Based On Accurate Brightness Detection

With the development of science and human living standards,on the basic requirements of traditional lighting design to light up space,people are more and more concerned about the impact of the light environment on human health,comfort and visual efficacy;traditional lighting and lighting design is changing to the people-oriented light environment design.The design and implementation of the human-oriented light environment need to be based on accurate characterization and precise control of the light environment.However,the existing illuminance-based light environment characterization and design system cannot directly reflect human visual experience,and there are also problems in sensor collection that are extremely susceptible to interference and too many sensor nodes.This paper takes the classroom scene as an example,research and exploration of light environment characterization and control based on brightness detection.This paper mainly carries out the following research:First of all,the paper analyzes the camera imaging principle and derives related formulas,then establishes the relationship model between scene brightness and pixel gray value.Based on the above research,we design a calibration experiment to restore the camera’s brightness response curve.In order to accurately obtain the brightness value of external scene,the paper studies a multi-exposure fusion algorithm,and realizes the accurate restoration of external brightness through a single camera.Secondly,the paper studies optical reflection characteristics of the object surface,and points out the importance of diffuse reflection pixel recognition(highlight pixel separation)in illuminance collection.Then according to the characteristics of classroom scene,a fast diffuse pixel recognition algorithm is implemented,and on this basis,a desktop illumination detection scheme based on brightness information is proposed.Finally,based on the proposed desktop illumination detection scheme and multi-exposure fusion algorithm,a classroom light environment control system is designed.The system mainly includes a light environment data detection module,brightness control module,narrow-band Internet of Things(NB-IOT)communication and host computer.The light environment data detection module acquires the classroom image through camera,then calculates the illuminance value of the target working surface,and uploads the data through NB-IOT communication;the brightness control module receives the control signal through NB-IOT communication,and then regulate the brightness of LED lights;The host computer includes server and visual interface for data storage and logic processing.On this basis,the system was tested in actual scenarios,the control and storage of light environment data were successfully achieved.The results show that the classroom light environment control based on brightness collection can obtain the brightness of the main illuminated surface of the classroom through imaging methods,and can meet the requirements of the completeness and accuracy of the light environment information by using fewer layout points;the brightness information can better meet human vision feeling,the conversion relationship between the brightness and illuminance established in the paper is also compatible with the current standards and methods.On the other hand,the light control system based on NB-IOT can meet the requirements of real-time and precise control.The relevant methods and conclusions of the research are also of reference significance to other application scenarios.