The Network Monitoring System Of PTZ Control Based On ONVIF Protocol

With the improvement of video monitoring technology, the most typical device high-speed dome network camera and its research is the focus of the market. This type of high-speed dome by controlling the rotation of PTZ to change camera’s direction and angle, to expand the monitoring range of video monitoring, PTZ plays in the monitoring system a very important role. However, different equipment manufacturer produce devices according to different interface standards, resulting in network video surveillance market lack of openness, the communication between PTZ control system and network camera has become a urgent problem to solve. Therefore, this article in an open network video interface standard ONVIF research basis, completed the PTZ control network monitoring system design, to communicate with the network camera supporting ONVIF standard, to realize network monitoring "standardization, interoperability."This paper first digs into the working principles of PTZ and the overall framework ONVIF standard interface for PTZ control, Then the function of the network monitoring system of PTZ carried on research design. Hardware design, the Ethernet based microcontrollers STM32F107 is chosen to core, mainly to complete stepper motor drive module design, using PWM to realize DAC conversion to control voltage breakdown, in order to ensure smooth rotation of the motor. Ethernet control module is detailed designed, the microcontroller STM32 with external network physical layer PHY chip is chosen to realize the network interface function, completion connecting of the internal network by switches and isolation transformer, in order to ensure PTZ can listen ONVIF protocol PTZ control packet.Software design, Free RTOS is chosen to software platform running, applications are divided into a number of different tasks, to improve the real-time performance of the system; Network protocol stack Lw IP to provide network service functions, in order to achieve the ONVIF network command parsing. Mainly to complete the program development of motor control module, using the method of the timer trigger to achieve PWM waveform. and the method of look- up table to C hange the PWM duty cycle, In order to achieve the stepping motor subdivision. The key to complete ONVIF protocol PTZ command parsing, using string search method to obtain the corresponding control commands and parameters, in order to achieve functional by PTZ to monitor PTZ packets of the client sent to the ONVIF camera, the STM32 processes controlling commands and drive stepper motor.Finally, PTZ control system and network camera are tested together, The debugging results shows, in this paper, the designed PTZ control system can be remote access via network, which can be reached interface communication requirements of the PTZ control, by adjusting the PTZ to change camera’s direction and angle, the real-time full-precise positioning accomplished.