NRI: FND: COLLAB: Optimal Design of Robust Compliant Actuators for Ubiquitous Co-Robots

NRI：FND：COLLAB：针对无处不在的协作机器人的鲁棒合规执行器的优化设计

• 批准号: 1830338
• 负责人: Elliott Rouse
• 金额: $ 31.87万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-15 至 2022-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1830338&HistoricalAwards=false
• 关键词: NRI; FND; COLLAB; Optimal; Design

Motion of robotic devices is achieved by enabling the movement of its joints by devices called actuators. This National Robotics Initiative (NRI) project seeks to understand how to design compliant actuators for human-interactive robots that are energy-efficient and safe across a wide variety of tasks and situations. Unlike rigid actuators, compliant actuators can store and release mechanical energy for greater efficiency and absorb shocks for greater safety, which has made them especially popular in wearable robots (i.e., prostheses and exoskeletons). However, the compliant element of the actuator (e.g., a spring between the motor and the robot joint) must be carefully chosen to achieve these benefits, which has restricted previous implementations to specific use cases. The mathematical framework in this project will enable design of compliant actuators that change their physical properties to guarantee safety and efficiency as interactions vary from gentle to forceful. Compliant actuators that are robust to a wide range of conditions can be used for many applications, allowing mass production at lower cost. The energy efficiency of these actuators will increase the battery range of mobile co-robots and allow the use of smaller, lighter batteries in wearable robots. This work is significant to the ubiquity of compliant actuator technology for safe, energy-efficient interactions between robots and humans in uncertain real-world situations outside the laboratory.This project will establish a robust convex optimization framework for designing series elastic actuators (SEAs) that globally minimize electrical energy consumption while satisfying actuator/safety constraints. When designing an SEA, a parametric representation of the elastic element (e.g., the stiffness of a linear spring) is typically optimized for a single task (trajectory and load). However, this paradigm has two key limitations: 1) solutions are only optimal within the given space of parameters, and 2) the benefits of the elasticity (i.e., efficiency and compliance) can be entirely lost outside of specific operating conditions. A nonlinear series elastic element can potentially solve these problems by providing different stiffness characteristics at different operating points, but the ideal parameterization of the spring is unknown. A non-parametric, robust optimization framework is therefore needed to develop SEA technology that can achieve a variety of tasks in a variety of situations (customizability) for ubiquitous interaction with humans (scalability). Tools exist to solve convex optimization problems with uncertainty in their parameters, but the design of SEAs is not currently known to be a convex problem. The overall goals of this project are then to 1) understand the convexity of SEA energy consumption as a function of stiffness characteristics, 2) understand how to design nonlinear series elastic elements to achieve maximal efficiency while satisfying constraints, and 3) understand how to design SEAs that are robust to uncertainties.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

机器人设备的运动是通过称为执行器的设备来实现其关节的运动。这个国家机器人倡议(NRI)项目旨在了解如何为人类交互机器人设计符合要求的执行器，使其在各种任务和情况下都是节能和安全的。与刚性执行器不同，柔性执行器可以存储和释放机械能量以提高效率，并吸收冲击以提高安全性，这使得它们在可穿戴机器人(即假肢和外骨骼)中特别受欢迎。然而，必须仔细选择致动器的顺应性元件(例如，电机和机器人关节之间的弹簧)才能实现这些好处，这限制了以前的实施仅限于特定的用例。该项目中的数学框架将使符合要求的执行器的设计能够改变其物理属性，以确保在相互作用从温和到强烈变化时的安全性和效率。适应各种条件的执行器可用于多种应用，从而以较低的成本进行大规模生产。这些致动器的能效将增加移动协作机器人的电池续航里程，并允许在可穿戴机器人中使用更小、更轻的电池。这项工作对于在实验室外不确定的真实世界中机器人与人类之间安全、高效地交互的柔顺执行器技术的普及具有重要意义。该项目将建立一个稳健的凸优化框架来设计串联弹性执行器(SEA)，在满足执行器/安全约束的同时使电能消耗全局最小。在设计SEA时，弹性元件的参数表示(例如，线性弹簧的刚度)通常针对单个任务(轨迹和载荷)进行优化。然而，这种模式有两个关键的局限性：1)解决方案只在给定的参数空间内是最优的；2)弹性的好处(即效率和合规性)可能在特定的操作条件之外完全丧失。非线性串联弹性单元可以通过在不同的工作点提供不同的刚度特性来潜在地解决这些问题，但理想的弹簧参数是未知的。因此，需要一个非参数、稳健的优化框架来开发可在各种情况下实现各种任务的SEA技术(可定制化)，以实现与人类的无处不在的交互(可伸缩性)。已有工具可以解决参数不确定的凸优化问题，但SEA的设计目前还不是一个凸优化问题。该项目的总体目标是1)了解海洋能源消耗的凸性作为刚度特性的函数，2)了解如何设计非线性串联弹性元件以在满足约束的同时实现最大效率，以及3)了解如何设计对不确定性稳健的海洋。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。