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

人类-机器人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的“十大想法”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力量，在包括制造、物流、军事、医疗、家居陪伴等各种场景中提高团队的综合性能。合作机器人发展的一个根本挑战是在高性能和确保人类安全之间取得平衡。在刚性方面，实现高性能(高精度和有效载荷)通常依赖于高刚性的协作机器人，而与人类的安全交互通常需要低刚性。本工作通过研究离散变刚度驱动器的新概念和开发高性能控制算法的系统设计方法，对柔顺机器人的刚度进行了基础研究，并通过实验测试进行了验证。在此基础上，展望了在不久的将来，具有可切换柔顺性的新一代机器人操作手的安全人机协同工作的前景。此外，开发的顺应性执行器将使机器人行业受益，其适应性顺应性动力学由行走机器人、外骨骼、娱乐、医疗和教育机器人与人类机器人的物理交互和内在安全需求的可变刚度实现。开发的技术将增强美国的高科技能力，并使其经济受益。融合的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科专业。对K-12代表不足的学生的早期参与和课程介绍将有助于培养未来的劳动力，使他们拥有机器人技能、知识和兴趣，以适应“工业4.0”时代的先进制造业。离散变刚度致动器(DVSA)项目对开发柔顺致动器的基础机器人研究做出了贡献，柔顺致动器是人-机器人协同合作的核心。新的执行器概念避免了现有的依赖于连续刚度变化机构的变刚度执行器(VSA)的问题，并带来了一种离散的设计方法，实现了快速选择刚度级别、低功耗、在刚度变化时零反向驱动力和紧凑设计。该项目将提供(1)确定典型离散刚度水平的设计准则，(2)开发DVSA离散变刚度机构的设计综合方法，(3)考虑机械啮合过程的详细离散刚度变化动力学建模，(4)DVSA操作稳定性和人-机器人安全交互的最优控制算法，(5)验证设计和控制方法的实验和仿真数据，以及(6)开放的软硬件平台，包括模块化DVSA执行器和3-DOF柔顺手臂。本项目得到了跨部门机器人基础研究计划的支持，该奖项由工程指导委员会(ENG)和计算机与信息科学与工程委员会(CEISE)共同管理和资助。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。

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.