The Study Of Auto-Focus Based On The Intelligent Control Of Stepping-Motor

In recent years, zoom cameras which are the core equipment of video monitoring systems can be seen everywhere. Zoom cameras are small with good flexibility and easy to install. So this paper researches zoom cameras and designs the control system of it. Firstly, this paper researches the key technologies such as the auto-focus technolgy, and the principle and structure of two-phase hybrid stepping-motor and the control of stepping-motor.Secondly, taking MCU as the core, this paper designs the hardware scheme. On base of that, this paper designs the detail circuits of every module. Thirdly, the procedure of soft ware development of stepping-motor and some module of software design are introduced.By the way of frequency domain band-pass method, video signals from CCD image sensor passed through a band-pass analog filter to pick up high frequency, which are used to construct simple focus evaluation functions. Auto focus systems based on frequency domain band-pass filter method are simply calculated and inexpensively cost. And aiming at the problems of traditional hill-climbing searching (HCS) algorithms, puts forward an optimized HCS model,which are twice searches in all to fix on the best imaging position, firstly cursorily searches in a wild bound with inconstant step length, secondly elaborately searches in a narrow bound with the minimal step length. The optimized HCS model is ushered into single-chip microcomputer based on the auto-focus system research platform and is able to acquire a rapid focussing speed and an accurate focussing effect.The design theoretically educes raising-lowering frequency curve of stepper motor, analyzes realization of raising-lowering frequency theory in actually two-phase hybrid stepping-motor running and finds out the optimal control method, then adopts raising-lowering frequency control method to eliminate the position loss of point to point position control and the mechanical impact of distance termination effectively by single-chip software strategy. By the way of micro-stepping control the design insures the two-phase hybrid stepping-motor runs more smoothly and analyses curve of running and research theory of it.Fuzzy control which imitates the abilities of illation and decision, is another form of intelligent control. Fuzzy control and its software realization are studied in the paper. In order to improve the partial and integral performance, this paper proposes the control method of Fuzzy-PID to select the factor with the different error. Compared with the traditional PID control and Fuzzy-PID control by simulation, Fuzzy-PID control behaves better than traditional PID control in many aspects of the control qualities. After Fuzzy-PID control is simulated, test results show that this method has good control effects. Realization show that, compared with the traditional PID control, the output response of Fuzzy control has smaller tunning time and faster stability and its control quality is better than the traditional PID control and enhance the ability of anti-interference to noise.