Abstract
摘要:動物在自然界中所具有的強大移動能力至今仍是任何人造系統所不可及。研究發現不論動物的外型或演化程度為何,其在地面上奔跑的運動狀態約略可以簡單的倒單擺模型來代表。加大柏克萊分校的Full教授提出了template和anchor的概念,來詮釋泛用足式運動之狀態:template由簡易物理模型組成(如倒單襬),提供運動控制之參考,anchor代表了原本系統複雜的肢體結構。這強調以template來控制協調運動的重要性,也首次定義了其和原本系統之間的相互關係。但是,這個概念下的許多關鍵點仍未釐清,使工程上進行設計與控制系統來展現動態特性仍是一個困難的挑戰。
足式系統中,運動的產生是由一個或數個足在時間軸上持續推進地面來產生,探討足的推進特性為必要之任務。因此,在本計畫中,主持人計畫有系統的以「設計與控制同步,理論與實務並行,生物和機械系統均涵蓋」的方式探討足的幾何彈性和驅動時脈對整體系統動態運動之影響。關鍵在對由anchor簡化到template的過程進行深度探討,先研究單足如何產生有效推進,再著墨如何融合多足推進以產生穩定的整體運動。研究內容涵蓋生物資訊收集與分析、足模型與整體系統模型之建立與比較、足系統製造與驗證、探討模行複雜度對運動之影響、並提供機器人設計與控制之流程與方法。
具有強韌且穩定動態運動的系統在工業界上一直都有強大需求,在人類無法有效研發突破之狀態下,反過頭來藉由瞭解生物系統以獲取靈感就成了一條有效的解決路徑。藉由這個生物與工程整合研發的計畫,我們相信目前兩研究領域間的鴻溝能漸漸縮減,並期待未來能結合成一個有效整合之領域。
Abstract: Animals have agile ability to perform rapid terrestrial locomotion where no mechanical devices can compete yet. Though their geometrical configurations and evolved stages vary significantly, researchers found that their dynamic running locomotion can be approximated by a simple mathematical model “SLIP” (Spring-Loaded Inverted Pendulum). Prof. Full at UC-Berkeley proposed hypotheses of general legged locomotion by the idea of template and anchor --- “templates” composed by simple mathematical models represent the prescriptive control guide (ex: SLIP), and “anchors” sketched the actuation joints and rigid structures represent of original complex biological systems more elaborately. These hypotheses emphasize the importance of templates for locomotion control purpose, and for the first time they further define a clear relation between the simplified models and the original systems. However, the answers to various associated questions remain unknown; therefore, to successfully design and control artificial systems to perform general dynamic locomotion remains a challenge task.
Since the general legged locomotion is composed by sequential/simultaneous propulsion of individual legs in time, to understand how each leg generates effective forces and moments to push body to the right directions seems to be the most fundamental and essential task. Thus, in this research proposal, the principle investigator would like to systematically address the effect of leg compliance morphology and leg actuation clock on overall legged locomotion, treating design and control all together, working in both theoretical and experimental aspects simultaneously, and studying on both biological and mechanical systems concurrently. The specific approach of this problem lies in the exploration of relation between anchors and templates in a more detailed level. Collapse dimensions from anchors to templates can be separated into two steps: First, simplify high degree-of-freedom (DOF) rigid limbs into low DOF compliant limbs, which collapses the effect of sequentially-connected joints into equivalent virtual actuated joint(s) (“clock”) and passive spring(s) (“compliance”). Second, further simplify the equivalent mechanisms of all legs into one final “virtual mechanism” to derive the simplest motion model (“template”). The first step focuses on how to generate the suitable propulsion force, and the second step addresses the issue of balance and stability.
The detailed research tasks are briefly described as follows: (1) Collecting locomotion data of biological systems, especially data of ground reaction forces and body configurations versus time. (2) Modeling of individual legs, systematically investigate the effect of composition and configuration of actuated joints, rigid links, and compliant links on the leg dynamic behaviors. (3) Designing and manufacturing of robotic legs for physical evaluation of models. (4) Modeling of the whole system with various simplified leg models, focusing on the effects of time/geometrical sequences of leg propulsion on the achievability of dynamic locomotion. (5) Investigate the effect of complexity of models on the locomotion and compare the locomotion similarity between models and the original biological systems. (6) and establishing a clear guideline about how to design the mechanical systems with specific dynamic behaviors.
Agile and stable motion generation is without-doubt desirable in many engineering applications. While the locomotion performance of artificial systems on irregular environments so far is limited, it is worth to understanding how the existing agile biological systems behave and extracting inspirations from the analysis. Through this multidisciplinary and frontier research we believe that current wide gap between biological and mechanical systems can be reduced and further be merged into an integrated research.
Keyword(s)
足系統運動狀態
足彈性特性
足驅動時脈
生物系統
機械系統
legged locomotion
leg compliance
leg actuation
template
biological systems
mechanical systems