Study On Wave Measurement System By Ship Motion In Navigation

Ocean is a new developing field which has a strategic significance. There are endless resources in the sea and we must give priority to the development of the ocean observation technology before developing and using it. The observation of wave plays a central role in the construction of marine engineering works. Nowadays, our country's wave measurement instruments are mainly used in a fixed point field and almost none of them can be used to measure real-time as the ship is sailing. It is necessary to design wave measurement system by ship motion in navigation in order to allow real-time measurements of wave for ocean-going ship as well as to ensure safe navigation of the ship.This paper hammers at one kind of high-tech and high reliability wave measurement system by ship motion in navigation. This measurement system uses the ship itself as the measuring instrument and it measures the wave by posture of the ship motion. One design of wave measurement system based on the DSP acceleration is proposed in this paper and it adopts an advanced DSP technology.This paper describes in detail design process of wave measurement system by ship motion in navigation and gives the system's overall design. Random waves are considered as a zero mean stationary random process according to wave theory, and then the model of a random wave is established. Ship movement is viewed as the output of the linear system under the disturbance excited by random waves. Combined the ship's sea keeping with spectral estimation theory and higher-order cumulants theory, the initial identification of frequency response characteristics for ship movement is carried out in AR model. Both hardware and software have been described in the design of DSP systems. DSP chip with a high-speed computing power is adopted to sample and process the sensor signal effectively; the digital filter and digital integration is used in the software to filter and process the acceleration signal, which can improve anti-disturbing capability and reduce hardware components. FFT algorithm is introduced in data processing to guarantee computation speed and to better ensure the real-time measurement of wave. The instrument can be used in the navigation of the ship, including on the night. It facilitates the safe navigation of ship and the accumulation of the reliable statistics on wave.The thesis can be divided into five parts. The first part discusses the domestic and international development of wave measurements according to the background of the program, and presents the key technologies used in this subject and its research significance. The second part describes simply research program on wave measurement system by ship motion in navigation. The third part introduces the wave's character and random wave's model concisely. It analyzes the fundamental relation between the gesture of the ship motion and the wave inspire on the basis of ship's sea keeping. The third part first tells about the calculations of the wave's eigen-value and then brings up the ship's motion model in terms of the ship's movement characteristics preliminarily. According to the ship's movement characteristics, the calculation of wave eigenvalue is introduced and the movement model of ship is proposed, and is also makes preliminary identification of the ship's motion frequency response characteristics. The fourth part discusses the wave measuring instrument's hardware design as well as software design. Finally, the results of this paper are analyzed, and the next step of work is expected.