An Expanded Analysis and Design Framework for Robots that Move by Reshaping their Limbs and Bodies

该项目旨在扩展对具有关节式身体和四肢的机器人运动的理解。步态是一系列的身体形状变化，其结束时的形状与开始时的形状相同，并且导致身体在其环境中的净重新定位。可以通过反复重复该序列来实现非常大的重新定位。四足动物的步态包括马的行走、小跑、慢跑和飞奔，以及瞪羚的蹬踏。机器人或动物可以根据需要使用特定的步态-例如，所需的行进速度将影响不同步态的相对能量效率。具有类似于动物的身体构造的机器人可能使用适应于自然的步态，然而并非所有机器人构造都具有明显的生物对应物。此外，严格的仿生方法可能会错过改善自然系统的可能步态。该项目将导出一个系统的数学框架，以在通常无法使用现有技术处理的情况下搜索理想的步态，包括机器人身体的某些运动无法主动控制，或者机器人的运动导致周围环境的变化，或者控制周围环境的属性以间接影响机器人的运动。这项工作的结果将应用于能够在水、沙子或泥浆等具有挑战性的介质中机动的机器人。这些结果将在搜索和救援，环境监测和恶劣环境的探索中具有潜在的用途。研究结果也将有助于深入了解生物有机体的运动策略。首席研究员有一个外展和教育活动的跟踪记录，包括研究生水平的机器人运动的教科书。步态运动利用系统与周围环境相互作用产生的反作用力的不对称性，以循环的方式获得净位移。机器人步态运动的最新研究已经建立了一个几何框架，用于以主纤维束的形式对系统的配置空间进行建模;在这样的制定中，系统-无论是机器人还是动物-都具有可以分为形状空间和位置空间的配置空间。步态是形状空间中的循环路径，当遵循时，会导致位置空间中的位移。这种纤维束结构已被用于非线性控制技术来分析和工程步态的机器人运动规划，但以前的工作已被限制到系统的自由度可以被整齐地分解成那些直接驱动和那些参数化的对称群。这样的系统只代表现实运动问题的一小部分，特别是，排除系统中的能量效率可以从涉及额外的未驱动的自由度的非线性动力学。该项目将扩展基于智能的建模和控制方法的适用性，以更广泛的一类问题，在孤独和合作运动，强调效率，敏捷性和设计原则的边界自然和工程系统。

This project seeks to extend understanding of locomotion in robots with articulated bodies and limbs. A gait is a sequence of body shape changes that ends with the same shape as it starts, and that results in a net repositioning of the body within its environment. Arbitrarily large repositioning may be achieved by repeating the sequence over and over. Examples of gaits in four-legged animals include walking, trotting, cantering, and galloping in horses, and pronking in gazelles. A robot or animal may use a particular gait depending on need -- for example, the desired speed of travel will affect the relative energy efficiency of different gaits. Robots with body configurations similar to animals may use gaits adapted from nature, however not all robot configurations have obvious biological counterparts. Furthermore a strictly biomimetic approach may miss possible gaits that improve upon natural systems. This project will derive a systematic mathematical framework to search for desirable gaits in cases that cannot generally be handled using the current state of the art, including where some movements of the robot body cannot be actively controlled, or where the movement of the robot causes changes to the surrounding environment, or where properties of the surrounding environment are controlled to indirectly influence the movement of the robot. The results of this work will be applied to robots that can maneuver through challenging media, such as water, sand or mud. These results will have potential uses in search and rescue, environmental monitoring, and exploration of hostile environments. The results will also give insight into the locomotion strategies of biological organisms. The Principal Investigator has a track record of outreach and educational activities, including a graduate-level textbook on robotic locomotion.Gait motions take advantage of asymmetries in the reaction forces generated from a system's interactions with its surroundings to gain net displacement in a cyclic way. Recent research in robotic gait locomotion has established a geometric framework for modeling a system's configuration space in the form of a principal fiber bundle; in such a formulation, a system -- either robot or animal -- has a configuration space that can be divided into a shape space and a position space. Gaits are cyclic paths in the shape space, which when followed, cause displacement in the position space. This fiber bundle structure has been used with nonlinear control techniques to analyze and engineer gaits for robotic motion planning, but prior work has been restricted to systems whose degrees of freedom can be neatly decomposed into those that are actuated directly and those that parameterize a symmetry group. Such systems represent only a fraction of the landscape of realistic locomotion problems, in particular, excluding systems in which energy efficiency can be derived from nonlinear dynamics involving additional unactuated degrees of freedom. This project will extend the applicability of symmetry-based methods for modeling and control to a broader class of problems in solitary and cooperative locomotion that emphasize efficiency, agility, and design principles at the boundary of natural and engineered systems.