Discrete Variable Stiffness Actuators with Fast Stiffness Switch for Safe Human-Robot Interaction

人机协同工作是未来工作的人类技术前沿，是美国国家科学基金会（NSF）的“十大创意”之一。协作机器人可以充分利用人类的智能和机器人的精度和强度，以提高在制造、物流、军事、医疗、家庭伴侣等各种场景下作为一个团队的综合性能。协作机器人发展的一个根本挑战是平衡高性能和确保人类安全。就刚度而言，实现高性能（高精度和有效载荷）通常依赖于高刚度的协作机器人，而与人类的安全交互通常需要低刚度。本工作通过研究离散变刚度作动器的新概念，开发了一种具有高性能控制算法的系统设计方法，并通过实验验证，对柔性机器人刚度进行了基础研究。在此基础上，设想在不久的将来，具有可切换顺应性的新一代机器人机械手可以实现安全的人机协同工作。此外，所开发的柔性驱动器将使机器人行业受益于可适应的柔性动力学，通过可变刚度实现步行机器人，外骨骼，娱乐，医疗和教育机器人与人机物理交互和本质安全的需求。开发的技术将增强美国的高科技能力，有利于美国经济。综合研究和教育工作将通过STEM工作坊和实践活动鼓励和激励年轻学生加入工程专业。早期参与和课程介绍K-12代表性不足的学生将有助于为“工业4.0”时代的先进制造业准备具有机器人技能，知识和兴趣的未来劳动力。离散变刚度致动器（DVSAs）项目有助于开发柔性致动器的基础机器人研究，这是协同人机协作的核心。新的执行器概念避免了现有的可变刚度执行器（VSAs）依赖于连续刚度变化机制的问题，并带来了一种离散设计方法，可以快速选择刚度水平，低功耗，零反驱动刚度变化，以及紧凑的设计。该项目将提供(1)通过涵盖人和机器人的安全，确定具有代表性的离散刚度水平的设计标准；(2)为DVSA开发离散变刚度机构的设计综合方法；(3)考虑机械接触过程的详细离散刚度变化动力学建模；(4)DVSA运行稳定性和人机安全交互的最佳控制算法。(5)验证设计和控制方法的实验和仿真数据；(6)开放式软硬件平台，包括模块化DVSA执行器和三自由度柔性臂。该项目由跨部门机器人基础研究项目支持，由工程（ENG）和计算机与信息科学与工程（CISE）联合管理和资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Human-robot co-working is at the human-technology frontier of the future of work, one of NSF’s “10 Big Ideas.” Co-robots allow the full use of human intelligence and robot precision and strength to improve the combined performance as a team in various scenarios including manufacturing, logistics, military, medical care, home companion and others. A fundamental challenge for the development of co-robots is balancing high performance and ensuring human safety. With respect to rigidity, achieving high performance (high accuracy and payload) often relies on high stiffness co-robots, while safe interactions with humans often requires low stiffness. This work conducts fundamental research on compliant robot stiffness by researching a new concept of discrete variable stiffness actuators and developing a systematic design methodology with high-performance control algorithms, validated by experimental tests. Based on this, a new generation of robot manipulators with switchable compliance for safe human-robot co-working is envisioned in the near future. Moreover, the developed compliant actuators will benefit the robotics industry with adaptable compliant dynamics enabled by variable stiffness on walking robots, exoskeletons, entertainment, medical and education robotics with human robot physical interactions and needs of intrinsic safety. The developed technology will enhance the US’s high-tech capability and benefit its economy. The integrated research and education work will encourage and inspire young students to join engineering majors through STEM workshops and hands-on activities. The early engagement and curriculum introduction to K-12 underrepresented students will contribute to preparing the future workforce with robotics skills, knowledge, and interests for advanced manufacturing in the “Industry 4.0” era. The project discrete variable stiffness actuators (DVSAs) contribute to the fundamental robotics research on developing compliant actuators that are central to synergistic human-robot collaboration. The new actuator concept avoids issues with existing variable stiffness actuators (VSAs) relying on continuous stiffness change mechanisms and brings a discrete design methodology for fast stiffness level selection, low power consumption, zero back driving force in stiffness change, and compact designs. The project will deliver (1) a design criterion in determining representative discrete stiffness levels by covering both human and robot safety, (2) a design synthesis method in developing discrete variable stiffness mechanisms for DVSAs, (3) detailed discrete stiffness change dynamics modelling considering the mechanical engagement process, (4) optimal control algorithms for DVSA operation stability and human-robot safe interaction, (5) experimental and simulation data verifying the design and control methods, and (6) open software and hardware platforms including a modular DVSA actuator and a 3-DOF compliant arm.This project is supported by the cross-directorate Foundational Research in Robotics program, jointly managed and funded by the Directorates for Engineering (ENG) and Computer and Information Science and Engineering (CISE).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.