測深波浪補償的修正研究

Abstract

在進行水深測量時，由於海面會不平靜，所以船體會隨著海浪的起伏而有所搖動，因此如果未進行船體運動的補償或修正，浪的運動位移量可能會顯示在繪製的地形圖上。因此地形圖品質的好壞取決於音鼓的選擇和是否有進行適當的船體運動修正。 'Heave'這個字用來表示相對於一個定義基準面的垂直距離。在本論文中，Heave 實際指得為物體受浪在重力向量上的起伏高度；如音鼓未裝設在重心位置上，其垂直位移量同時會受到左右搖擺（roll）及前後點頭（pitch）的效應，並反應在測得的水深值上。測深時大多可利用運動感應器�波浪補償器來紀錄船隻隨浪的運動變化量，其中是由波浪補償器去記錄抬升的運動量而修正平滑此起伏效應。 很多軟體使用者或資料處理者往往以為將波浪補償器接上測深系統，它自動就會將波浪補償值修正好，卻忽略了修正效果的可信度，我們的實驗結果發現，軟體設定中音鼓或波浪補償器位置的誤用，會使得修正後的水深資料值有誤。因此我們去驗證處理軟體的計算方式，確定其修正原理，並利用在馬祖外海的地形測量資料，利用計算原理置換原本運動感應器架設在船舷邊紀錄到的波浪起伏值，再讓Hypack軟體重新計算，得到的修正效果改善許多，25 公尺的水深留下約正負5 公分的起伏量，符合波浪補償值的修正精度，因此調整重心位移修正結果仍在誤差範圍內。

Waves causes ship’s motions. Therefore, wave motions will be reflected in bathymetry record when water sounding survey is conducted without any heave compensation. As a result, the quality of bathymetrical map may relies partially on the choice of transducer and the fittness of heave. The word “ Heave” is used to express a vertical displacement with relative to from a mean level. In this thesis, if the transducer is not positioned at the location of the mass center of the ship, heave shall be combination of gravity motion of sea waves, and the roll/pitch motions of the ship itself. Generally, the motion sensor/heave compensator are linked with bathymetry system to correct the heave motion caused by sea waves. It indicated that whether or not the heave compensation is functionable, it can not depend purely on the heave compensation being installed when using a data logger. In our experiment , when we define the parameters in a software according to the description in the manual careless, it would easily create problem doing heave compensation. In this thesis, when the motion senser was installed by the side of the survey boat in the Machu project, we need to calculate the heave values of every measurement at boat mass center, and replace them in the record. After that, the compensation can be fullfilled using the Hypack software,and error margin shall be within +/-5 cm at 25m of depth range. It is also proved that the location of mass center of the boat is determined with confidence.