Research On Lighting Control System In Smart Home

To solve the existing problems of the lighting control system such as single control mode,bad scalability and poor control effect etc.,a kind of lighting control system applied in smart home has been researched.This system integrates the network communication and the lighting control which can achieve accurate and diversified control of lighting.The main works of the thesis are as follows:(1)The scheme design of the lighting control systemThe present situation of intelligent illumination control system is analyzed,and the problems existing in the lighting control system are summarized,the demand of lighting control system is determined.The main protocol of the field in the lighting control system is analyzed and the architecture of the system is determined.The threelevel distributed control system is composed of the mobile terminal,controller and dimmer.Considering the communication performance and program cost,the Ethernet and the RS-485 serial bus are chosen as the communication network respectively.On this basis above,a detailed communication transmission protocol is designed.The light modulation method is analyzed and determined by using the PWM dimming mode.(2)The hardware design of lighting control systemThe hardware design of lighting control system includes two parts: the controller and the dimmer.In allusion to the functions requirement of controller,the processor AM3352 is selected as the controller CPU,in order to communicate with the router,the Ethernet control circuit is designed,and STM32F205 is used as coprocessor to communicate with the multiple dimmer.For the dimmer,the STM32F103RBT6 is used as the main control chip,to communicate with the controller through RS-485 communication circuit,the cross-zero detection circuit and the PWM dimming control circuit is designed to realize the adjustment and control of the lighting brightness.(3)The software design of lighting control systemAccording to the layers distribution,the controller can be divided into driver layer,application layer and software layer.The modularized software design idea is adopted in the dimmer,such as the program of serial communication,cross-zero detection and PWM dimming,etc.(4)The test and result analysis of the lighting control systemThe principle analysis of the communication factors of the lighting control system is made.The best performance parameters of the lighting control system are determined according to the test results: baud rate is 38400,communication timeout time is 7ms,and the longest communication distance is 500 m.Based on the nonlinear characteristics of the light curves to human eyes,the corrected PWM duty cycle is obtained by gamma correction algorithm.The test results show that the duty ratio of the adjustable brightness changes qualify the requirements of the human eye vision of linear.The tests of local operation function of dimmer and the terminal operation of mobile phone show that the system operates with great efficiency and meets the functional requirements.