Research Of Maritime Fallen Overboard Automatic Alarm System Based On Beidou

Our vast sea area is about 300 square kilometers. With the steady development of China’s economy year after year, the demand for resources in sea increase gradually,the development and utilization of marine resources gradually increase into the marine engineering, fisheries, exploration and development of mineral resources, marine resources, marine science and space-related personnel and resources is gradually increasing. At the same time, changing the subject to the harsh marine environment, the various maritime distress drowning incidents frequently occur, a serious threat to life and property safety of offshore workers.For the accident of man overboard at sea, rescue workers rely mainly on the executive search model based on theory or drifting eye to find. With the development of science and technology, there has been an increasing number of maritime life-saving appliances, to some extent,to solve the difficult problem of drowning rescue, but there are still some problems like single function or a high false alarm rate. When hanppening emergencies of drowning accident at sea, timely and accurately identifying and locating their position is the premise rescue work.In order to ensure safety of life at sea, combining technology of Compass and wireless communication, designed a man overboard at sea to automatically detect and alarm system for help, when a drowning situation emerges, timely and effectively detecting the falling state, and through the wireless data the transfer will send location information to the drowning ship or ships in the vicinity. The system consists of a help terminal and a ship terminal, functions of the help terminal are to detect drowning state of main user and alarm to call for help after falling into the water, shipborne terminal is to complete receiving distress signals transmitted by help terminal, and judging if falling into water. When the water signal is detected, alarm immediately and notify the relevant personnel for rescue.First, according to the function of the system of the entire system hardware design. In the help terminal hardware design, I choose STM32 MCU as the control unit, which completes the processing of other chips for control and data. Achieving of positioning function relies on the UC221 Beidou chip and wireless transceiver chip nRF905 completes the communication between terminals. Adopting acceleration sensor, a pressure sensor and condensation sensor by detecting the acceleration, pressure and humidity to determine whether the wearer is drowning state. The acceleration threshold obtained by many experiments, the pressure threshold is obtained through theoretical calculation, humidity threshold is based on the characteristic curve condensation sensor may be. Taking into account the power consumption of help terminal is small, a lithium battery of + 5V power can supply for the terminal. Shipborne terminal power supplies module and a wireless communication module and help the same terminal, the terminal interface RS-232 C connection to the PC via a serial, use nRF905 chip to communicate with the user to set up and make judgments based on the water sent to the data, when it is detected data-drowning alarm immediately after the distress message, a timely reminder of man overboard distress situation occur quickly and rescue. The alarm module is realized through the buzzer. In the hardware design, PROTEL DXP is used for schematic design and PCB design.Secondly, it is the software design of the whole system which details its work flow chart of each module.In the Software design, the focus of the transceiver chip nRF905 process of data acquisition as well as accelerometer pressure sensor data collection was compiled by C language, the parsing process for Compass has been described in detail. Taking into account the number of the help terminal system and choose the TMDA time division multiple access communication technology to improve communication efficiency.Finally, in order to verify the feasibility and stability of the system, unpack the hardware debugging, software debugging and debugging of combination between hardware and software. After debugging, slove and analyze for the effect of Beidou positioning, the positioning error is within10 m.The test shows that when offshore operation personnel fall into water, the help terminal can rapidly and effectively detect drowning person’s status and automatically send drowning distress signals, then shipboard terminal detects the data and determines the distress signal immediately to alarm with sound and light for rescue timely. The system is reliable with high correct rate of drowning detect and low false alarm rate compared with similar system, which provides effective security for offshore workers.