The Design Of The Safety Monitoring System For The Manhole Cover Of The Underground Comprehensive Pipe Gallery

The underground pipe gallery is the new municipal infrastructure,and it is of great importance to the safety,function,landscape and development of the whole city.Thus,the smart manhole cover applied into underground pipe gallery has attracted much attention from scholars.This paper mainly focuses on the control system that can remotely monitor the security of manhole covers in underground pipe gallery.But considering the reality,the manhole cover on the road can not avoid being crushed by the car.So it is necessary to identify the different vibration of the car's roller cover and the other heavy objects.The system based on the two-circuit redundant communication of nRF24L01 wireless communication and RS-485 wired communication transmit the alarm signal to the remote monitoring center and send alarm information to the supervisors by utilizing the GPRS function to ensure the safety of manhole cover.Normally,the maintenance staff require to open covers through the remote control after host authorizing a certain cover,otherwise,it will alarm.And the entire system contains three subsystems:1)Remote control.The remote control has set key,increase/open key,enter/transposition key,decrease key and power key,utilize the wireless network to open the solenoid of any address code by entering the specified cover number and correct authorization code,and then use a wrench to open it.2)Host control box.It the cover needs to be opened,the host put in the remote monitoring center sends the authorization code to the opened manhole cover through the wireless network and the 485 bus,then we can use the remote control to open it.When the travel switch detects that a manhole cover is opened or the vibration sensor is subjected to violent attack illegally,the slave can send an alarm signal to the host to further display the address,in order to send to the message to supervisor.3)Each manhole cover has a slave control box,which is in the receiving state normally.When the encrypted authorization code is transmit by the host,the authorized slave nixie tube can display the decrypted authorization code,and wait for the inform of remote controller.When the travel switch detects that the manhole cover is opened illegally,the slave in the sending state can immediately send an alarm signal through the wireless network and the 485 bus.Sometimes,if the alarm information and authorization information arrive at a slave at the same time,the wireless module can easily solve it through utilizing its multi-channel bidirectional transmission function.This paper first describes the status quo of wireless network technology,fieldbus technology and related vibration of vehicle,and briefly introduces nRF24L01 and RS-485 bus.Secondly,the theory of vibration signal acquisition and analysis processing is described.The parameters and sampling theorem of vibration signal and the mixing of signal are introduced,and then the analysis and processing of the signal,including the statistical processing of time domain signal,probability distribution and time-frequency transformation method-Fourier transform.Then,based on the design of the overall system scheme,the paper analyzes the wireless network and wired communication,specifies the system in the aspects of hardware and software design,.Finally,the paper further conducts the experiment,and the results show that the system has normal communication and reaches the design requirements,and the method of identifying the manhole cover of a vehicle's well cover and a hammer can be achieved.