RI: Small: A New Mechanical Coupling Metric to Enable Effective Biped Locomotion Control

RI：小：一种新的机械耦合指标，可实现有效的两足运动控制

• 批准号: 1527393
• 负责人: John Goodwine
• 金额: $ 49.41万
• 依托单位: University of Notre Dame
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1527393&HistoricalAwards=false
• 关键词: RI; Small; New; Mechanical; Coupling

Legged locomotion has evolved to provide the primary means of locomotion for land-based mammals, including humans. While highly-structured or artificial environments may lend themselves to alternative means, legged locomotion still provides the most effective way to traverse many locales. These include uneven natural terrains, human-designed environments featuring steps and staircases, and disaster rubble consisting of natural and/or human-made elements. Because they mimic the human structure, biped robots are of particular interest for operation in human-designed environments and performing human-assistive tasks alongside their human counterparts. Several decades of research efforts have sought to move biped robots out of laboratories and enable them to perform a wider range of practical tasks in real-world environments. A fundamental challenge that remains before this vision is fully realized, though, is how to enable robots to move in the very dynamic and efficient manner of humans while still maintaining the excellent stability that humans exhibit. Most modern biped robots either move relatively slowly and thus expend an excessive amount of energy or else move more rapidly and efficiently, but are too susceptible to falls caused by only minor disturbances. This project seeks to enable the development of biped robots that move more like humans, in terms of both efficiency and robustness. It formulates and applies a new, more general metric of dynamic robot control and stability that exploits the underlying mechanics of human-like locomotion, demonstrating its utility in laboratory robot experiments. The broader impact centers around encouraging K-12 students to pursue higher education in the STEM disciplines by highlighting engineering connections between robots and children¹s own primary means of locomotion -- walking.This project seeks to formulate and experimentally validate a novel approach to biped locomotion control based on an analytical measure of the control authority over the unactuated degrees of freedom. Legged locomotion systems are inherently underactuated because there are no actuators at the points of contact between the feet and the ground. The approach in this project exhibits the four characteristics of a universal dynamic control authority metric that would enable the design of controllers to produce gaits that are both robust and efficient, characterized by 1) generality of application to a range of movements; 2) flexibility for use with a variety of mechanical designs; 3) consistency with the natural dynamics to yield energy efficient gaits; and 4) analyticity to enable systematic mechanical and control design. The basic approach is, at any state, to decompose system velocities into directions that are aligned with the inputs, termed the controlled velocities, and directions orthogonal (with respect to the kinetic energy metric) to the inputs, termed the orthogonal velocities. A computable measure of coupling between the controlled and orthogonal velocities quantifies the control authority of the system over the unactuated DOFs and is the basis for the new dynamic control metric. Configurations where there is complete decoupling between the controlled and orthogonal velocity directions are referred to as dynamic singularities. Strong coupling is advantageous for the system to have good disturbance rejection properties, while weak coupling is desirable for the system to have good disturbance isolation properties. Thus, the project examines how a thorough understanding of the nature of the disturbances can be used to exploit dynamic singularities in the control of dynamic biped gaits.

腿运动已经进化为包括人类在内的陆地哺乳动物提供了主要的运动方式。虽然高度结构化或人工环境可能有助于替代手段，但腿运动仍然是穿越许多地区的最有效方式。这些包括不平坦的自然地形，人为设计的环境，包括步骤和楼梯，以及由自然和/或人为元素组成的灾难瓦砾。因为它们模仿人类的结构，所以机器人在人类设计的环境中操作，并与人类同行一起执行人类辅助任务，特别令人感兴趣。几十年的研究努力试图将机器人从实验室中移出来，使它们能够在现实环境中执行更广泛的实际任务。然而，在这一愿景完全实现之前，一个根本的挑战仍然是如何使机器人能够以人类非常动态和高效的方式移动，同时仍然保持人类表现出的出色稳定性。大多数现代机器人要么移动得相对较慢，从而消耗过多的能量，要么移动得更快、更有效，但太容易受到仅由微小扰动引起的福尔斯的影响。该项目旨在开发更像人类的机器人，在效率和鲁棒性方面。它制定和应用了一个新的，更普遍的动态机器人控制和稳定性的度量，利用类似人类的运动的基本力学，在实验室机器人实验中展示其实用性。更广泛的影响集中在鼓励K-12学生追求STEM学科的高等教育，通过强调机器人和儿童自己的主要运动方式-步行之间的工程联系。该项目旨在制定和实验验证一种基于非驱动自由度控制权威的分析测量的新型运动控制方法。腿式运动系统本质上是欠驱动的，因为在脚和地面之间的接触点处没有致动器。本项目中的方法展示了通用动态控制权威度量的四个特征，这将使控制器的设计能够产生鲁棒且高效的步态，其特征在于：1）应用于一系列运动的通用性; 2）与各种机械设计一起使用的灵活性; 3）与自然动力学一致以产生节能步态;以及4）能够进行系统的机械和控制设计的分析性。基本方法是，在任何状态下，将系统速度分解成与输入对齐的方向，称为受控速度，以及与输入正交的方向（相对于动能度量），称为正交速度。控制和正交速度之间的耦合的可计算的措施量化的控制权限的系统在未驱动的自由度，是新的动态控制度量的基础。在受控速度方向和正交速度方向之间存在完全解耦的情况被称为动态奇点。强耦合有利于系统具有良好的干扰抑制性能，而弱耦合则有利于系统具有良好的干扰隔离性能。因此，该项目研究如何彻底了解的性质的干扰，可以用来利用动态奇异性的控制动态megaits。