Research On ZigBee Based Ship Airbags-Launching Pressure Monitoring System And Energy Saving Method

Ship launching with airbags is a ship launching method which was pioneered by China,which has the advantages of low investment cost,high launching efficiency,flexibility and convenience,and has been widely used in various shipyards.The airbags are always under high pressure during the preparation for ship launching.Once ruptured,it will lead to the damage of protruding parts such as the bottom of the ship or the propeller,and even cause casualties.Therefore,real-time monitoring of airbag pressure is required.The traditional ship launching process adopts manual inspection to monitor the air pressure of the airbags,which has a series of defects such as error-prone readings,feedback lag and high labor costs.In order to solve the above problems,this thesis established a ZigBee-based airbag launching pressure monitoring system.Wireless sensor networks were used to collect and analyze airbag pressure data,real-time monitoring of the air pressure of each airbag and alarm for abnormal situations.In addition,since the wireless sensor device is mounted on the airbag,the airbag moves with the ship,so the wireless sensor can only be powered by a battery with limited capacity.In order to improve the endurance of wireless sensor equipment and reduce charging times,energy-saving methods are studied to optimize the energy consumption of the system.The specific research contents are as follows:（1）Study ZigBee wireless communication technology and summarize the technical characteristics,equipment types,topology structure and protocol framework of ZigBee communication.At the same time,the research status of wireless sensor networks is investigated,and the existing energy-saving technology of wireless sensors networks is analyzed.（2）Aiming at the deficiencies of the existing airbags air pressure monitoring solutions,a ZigBee-based marine airbag launching air pressure monitoring system was developed.Aiming at the problems of complicated structure and easy damage to the socket caused by wired charging of end-device,a wireless charging module is designed and modularized.At the same time,in view of the lack of a visual management platform,the host-computer software was developed,and the communication instructions of the system were designed to realize realtime management and display of ZigBee network equipment and airbags air pressure data.（3）An adaptive sampling algorithm based on multi-step prediction is proposed to solve the problem of limited energy supply of end-device in the pressure monitoring network.The proposed algorithm uses the autoregressive model to synchronously predict the air pressure data on the host computer and the terminal,and uses the step size update mechanism to adaptively adjust the sampling period.It is realized that the terminal node adaptively reduces the sampling frequency and communication frequency under the condition that the air pressure data is accurate,thereby reducing the energy consumption.（4）An experimental platform for the air pressure monitoring system was built to verify the software and hardware functions of the monitoring system.The experimental results show that the ZigBee device works normally,and the upper-computer software realizes the node management function and real-time acquisition and display of the air pressure data uploaded by each End-device,which meets the design requirements.At the same time,three groups of pressure data samples were obtained on the experimental platform to verify the proposed energy-saving algorithm,and the energy-saving effect of the algorithm and the fitting accuracy of pressure data were analyzed.Experimental results show that,for pressure data samples 1,2 and 3,the proposed algorithm in this thesis can fit RMSE values of 0.141,0.115,0.068 and MAE values of 0.101,0.085,0.040,respectively.Compared with the conventional periodic sampling method,the energy consumption of energy terminal nodes is reduced by 39.93%,42.19% and 45.46%.Moreover,compared with other comparison algorithms,it has better energy saving performance and higher fitting accuracy of pressure data.The proposed energy-saving algorithm is expected to effectively reduce the energy consumption of End-device and improve their endurance.