臺灣博碩士論文加值系統

隨著物理模擬技術的成熟，目前相當多電影與遊戲都加入物理模擬技術，使物件之間互動更為自然。但是要在三維物理模擬環境下，重現動作捕捉器動畫相當困難，因為不容易維持模擬人體的平衡。
本篇論文提出新方法，可以在物理模擬環境下，即時(real-time)控制三維兩腳角色重現目標動作捕捉器動畫，並動態對外界影響做出反應。本篇論文是利用倒單擺代表整個人體，並即時去改變動作路徑，使模擬人體身體與動作捕捉動畫人體維持相同的狀態。除了重現動作捕捉器記錄下來的動畫外，在不同的地形與外力影響下，亦可維持平衡。此外，用於控制人體做出目標姿勢的技術中，最常見的控制技術是比例微分控制器(Proportional - Derivative controllers)。但是此種控制器需要微調參數，不同動作的參數皆不同。因此本篇論文提出一個速度驅動控制器(velocity-driven)，只需要粗略設定一組參數，即可做出各種類型的動畫。
本篇論文提出的控制器，可以在即時(real-time)運算下，控制模擬的人體跟隨目標動畫。並可以隨時改變地形、給予外力、改變姿勢，或使用者給予的動作限制，皆可立即(real-time)反應在模擬人體上，並保持平衡。

This paper present a physics-based approach to generate 3D biped character animation that can react to dynamical environments in real-time. Our approach utilizes an inverted pendulum model to on-line adjust the desired motion trajectory from the input motion capture data. This on-line adjustment produces physically-plausible motion trajectory adapted to dynamic environments, which is then used as the desired motion for the motion controllers to follow in dynamics simulation. Rather than using the Proportional-Derivative controllers whose parameters usually cannot be easily set, our motion following control adopts a velocity-driven method which computes joint torques based on the desired joint angular velocities. Physically-correct full body motion of the 3D character is computed in dynamics simulation using the computed torques and dynamical model of the character. Our experiments demonstrate that MOCAP-following with real-time response animation can be achieved easily. Besides, physically-plausible motion style editing and automatic motion transition can also be generated naturally.

中文摘要 i
英文摘要 ii
目錄 iv
圖目錄 vi
1. 導論 1
1.1 研究動機 1
1.2 研究目的與貢獻 3
1.3 章節介紹及研究方法流程 3
2. 相關研究 6
2.1. 動作捕捉器動畫之應用 6
2.2. 動作合成 7
2.3. 結合動作捕捉器動畫與物理模擬 10
2.4. 物理模擬引擎技術 17
2.5. 倒單擺 19
3. 系統架構 21
3.1. 系統簡介 21
3.2. 系統流程 22
4. 倒單擺模型 24
5. 平衡控制 28
5.1. 從Mocap data中取得動作資訊 28
5.2. 被動反應－擺動腳(swing leg) 29
5.3. 預測質心的路徑 31
5.4. 預測下一步的位置 32
5.5. 二維與三維的結合 33
5.6. 主動反應－支撐腳(Support leg) 34
5.7. 踝關節角度 35
6. 跟隨控制器 37
7. 動作規劃 41
7.1. 轉彎 41
7.2. 站立平衡控制 42
8. 實驗結果 44
8.1. 站立 46
8.2. 跟隨Motion capture data並保持平衡 47
8.3. 產生符合物理的動作與動作切換 49
8.4. 對外界的反應 50
8.5. 改變身體參數 53
9. 結論與未來方向 55
9.1. 結論 55
9.2. 討論與未來方向 55
9.3. 方法限制 56
10. 參考文獻 57

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