本研究旨在建立一套低成本、高解析度之聲學合成孔徑成像與運動估測流程。相較於光學與毫米波成像系統，聲學系統具有硬體成本低、訊號產生容易等優點，適合用於低成本成像。然而，受限於實體陣列孔徑，傳統聲學陣列之方位向解析度有限，因此本研究導入合成孔徑雷達（Synthetic Aperture Radar， SAR）概念，透過平台滑動形成虛擬大孔徑，以提升聲學影像之橫向解析度。 首先以空氣中的麥克風陣列建立聲學 SAR 系統，使用 FMCW Chirp 訊號進行滑動掃描，並透過空場扣除與通道估測降低直達波及背景反射干擾。完成前處理後，進行二維 SAR 成像，結果顯示聲學SAR 可呈現目標主要反射區域，並初步驗證低成本聲學合成孔徑成像之可行性。此外，本研究亦利用 4×4 麥克風陣列之多通道二維影像進行三維投影，以觀察目標於空間中的能量分布。 實驗過程中可發現，SAR 成像品質高度依賴掃描軌跡之準確性。當平台接近等速移動時，目標能量較容易聚焦；反之，若存在非等速移動、加減速或位置誤差，慢時間相位歷史將無法正確對齊，導致影像散焦與能量分散。為解決此問題，本研究進一步於水下 S-sharp 聲納系統中導入振幅轉向陣列成像（Amplitude Steered Array Imaging， ASAI），由回波訊號中估測平台速度與位置，作為 SAR 軌跡補償之基礎。 在 ASAI 運動估測中，透過 range path 追蹤、角度估測與多路徑融合，推估平台相對位置與速度。結果顯示，ASAI 估測軌跡與實際運動趨勢具有高度相關性，並可作為 SAR 成像補償之輸入。;This study aims to establish a low-cost and high-resolution acoustic synthetic aperture imaging and motion estimation framework. Compared with optical and millimeter-wave imaging systems， acoustic systems offer advantages such as low hardware cost， easy signal generation， and clear time-delay differences in short-range measurements， making them suitable for low-cost imaging applications. However， due to the limited physical aperture of conventional acoustic arrays， the azimuth resolution is restricted. Therefore， this study introduces the concept of Synthetic Aperture Radar (SAR)， in which a virtual large aperture is formed through platform scanning to improve the lateral resolution of acoustic images. First， an acoustic SAR system was implemented using a microphone array in air. FMCW chirp signals were transmitted while the platform was scanned to synthesize the aperture. To reduce the influence of direct-path signals and background reflections， empty-scene subtraction and channel estimation were applied as preprocessing steps. After interference suppression， two-dimensional SAR imaging was performed. The results show that SAR can reveal the main reflection regions of the target， thereby preliminarily verifying the feasibility of low-cost acoustic synthetic aperture imaging. In addition， multi-channel two-dimensional images from a 4×4 microphone array were further projected into a three-dimensional space to observe the spatial energy distribution of the target. During the experiments， it was observed that SAR imaging quality is highly dependent on the accuracy of the scanning trajectory. When the platform moves at an approximately constant velocity， the target energy can be more easily focused. In contrast， non-uniform motion， acceleration， deceleration， or position errors may cause the slow-time phase history to become misaligned， resulting in image defocusing and energy dispersion. To address this issue， this study further introduces Amplitude Steered Array Imaging (ASAI) in an underwater S-sharp sonar system to estimate the platform velocity and position from acoustic echo signals， providing a basis for SAR trajectory compensation. In ASAI-based motion estimation， the relative position and velocity of the platform are estimated through range path tracking， angle estimation， and multipath fusion. The results show that the ASAI-estimated trajectory is highly correlated with the actual motion trend and can serve as an input for SAR imaging compensation.
