| Summary: | 在製作動畫上，模擬人體的運動一直是困難的課題；但在如線上遊戲等急速成長的虛擬環境應用中，人物運動的動畫常是不可或缺的一環。過去在此方面的相關研究雖然為數不少，但大多數的系統皆只適用於某特定的地形或事先給定的腳步落點；能根據地形特徵而自動產生對應之行走運動者並不常見。本論文提議的系統，便是一個能即時模擬人體走路動作的運動計劃器。我們以反向關節運動的方式，分析人體在不平路面上行走時的運動特徵，並以貝茲曲線表示懸浮腿的運動軌跡。透過貝茲曲線控制點的調整，可以讓下半身的肢體避免碰觸到凸起的路面。其次，此系統也包含了腳步計劃的機制，讓虛擬人物能以行進效率為準則，計劃未來數步內保證可行的步伐。再者，我們根據實際測量的資料與觀察，找出行進過程中每個階段在時間分配上的差異，並利用製作動畫的原理，加入緩入與緩出的概念，以調整行走步伐的節奏，使動畫更具真實感。最後，我們將此模擬系統套用於「線上模擬」與「即時操控」兩種不同模式的應用系統，以驗證此系統之即時性與實用性。 === Simulating human motion has been an important and challenging topic in computer graphics for many years, especially after the booming of virtual environment applications such as on-line games. Although there has been much research on this topic, most previous systems are only capable of generating a realistic locomotion for a set of given footsteps on a flat ground in an off-line manner. The system we propose in this thesis is a lower-body motion simulator for humanoid capable of planning efficient footsteps and automatically generating collision-free locomotion in real time. First, we observe and analyze the motion characteristics of human walking and use Bézier curves to represent the trajectory of a floating leg during a stride. We use an inverse kinematics approach to compute the corresponding joint angles for a given leg trajectory. By adjusting the control points of the curve, we can change its shape to avoid collisions with the ground. Second, the system also includes a footstep planner that can generate successful and efficient gaits over an uneven terrain with an empirical energy consumption model. Third, according to observation and measured data, we use the “ease-in” and “ease-out” techniques and appropriate timing for each phase of a walking cycle to generate more realistic motions. Finally, we have applied this motion simulator to a virtual environment system with two types of operation modes: on-line simulation and real-time navigation which are verified the efficiency and practicability of such a system.
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