Maximizing energy efficiency of variable stiffness actuators through an interval-based optimization framework
Maximizing energy efficiency of variable stiffness actuators through an interval-based optimization framework
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DOI：
10.1016/j.sna.2021.113123
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发表时间：
2021-12
期刊：
影响因子：
--
通讯作者：
Trevor Exley;A. Jafari
中科院分区：
文献类型：
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作者：
Trevor Exley;A. Jafari
尽管需要能够调节机器人平台与人体物理接触时的刚度，并且迄今为止已经开发了大量不同的可变刚度执行器，但仍然没有这样的执行器能够成功地通过实验室研究阶段并转移到实际应用中。其主要原因是由于缺乏对如何优化设计的刚度调整机制的基础上，每个应用程序的期望性能的理解。如果不进行优化设计，执行器内部的额外复杂性将阻止在刚度调整机制的好处与成本之间进行权衡，例如弹性元件的能量存储容量与执行器输出（即链接）实际释放的能量相比。目前，这种权衡标准不赞成在执行器中引入刚度调节机构。因此，在许多实际应用中，通常选择具有主动柔度的简单串联弹性致动器，而不是复杂的变刚度致动器。这项工作通过开发一个框架，可以最大限度地提高可变刚度执行器的能量效率，从而了解如何优化设计刚度调整机构的参数。基于所提出的优化框架，对五种不同的刚度调整机构设计进行了考虑和评估。然后，就能源效率而言，将每组的最终优化设计与原始设计进行比较。提出的框架显示能源效率的提高高达354%，同时满足设计约束。
Despite the necessity for being able to regulate the stiffness of the robotic platforms in physical contact with humans, and tremendous number of different variable stiffness actuators that have been developed so far, there is still no such actuator that has successfully passed the research lab phase and transferred into a real application. The main reason is due to the lack of understating on how to optimally design a stiffness adjustment mechanism based on desired performances of each application. If not optimally designed, the additional complexities within the actuators, prevent to win the trade-off between benefits of having a stiffness adjustment mechanisms versus its costs, such as the energy storage capacity of the elastic elements compared to how much energy can be actually released at the output of the actuator, i.e. the link. Currently, this trade-off criterion is not in favor of introducing a stiffness adjustment mechanism into the actuator. Therefor, generally, having a simple series elastic actuator with active compliance has been preferred over having a complex variable stiffness actuator, in many real applications. This work develops an understanding of how to optimally design the parameters of a stiffness adjustment mechanism by developing a framework that can robustly maximize the energy efficiency of variable stiffness actuators. Five different design sets of stiffness adjustment mechanism are being considered and evaluated based on the proposed optimization framework. The resultant optimal design of each set is then compared with the original design in terms of energy efficiency. The proposed framework shows improvement of energy efficiency up to 354%, while design constraints are all being satisfied.