Soft-actuators in cyclic motion: Analytical optimization of stiffness and pre-load
Soft-actuators in cyclic motion: Analytical optimization of stiffness and pre-load
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DOI：
10.1109/humanoids.2013.7029999
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发表时间：
2013-10
期刊：
影响因子：
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通讯作者：
Alexandra Velasco;G. M. Gasparri;M. Garabini;L. Malagia;P. Salaris;A. Bicchi
中科院分区：
文献类型：
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作者：
Alexandra Velasco;G. M. Gasparri;M. Garabini;L. Malagia;P. Salaris;A. Bicchi
在本文中，我们研究了软驱动在降低执行循环任务的机械系统的能量成本方面的作用。目标是确定最优刚度值和弹簧预载，以使给定的成本函数最小化。为了进行分析，我们考虑了使用弹性驱动器的全驱动和欠驱动机械系统，根据弹簧相对于驱动器和负载的放置方式和位置，这些弹性驱动器可以是串联弹性驱动器（SEAs）或并联弹性驱动器（PEAs）。能量消耗不仅取决于驱动参数，还取决于执行给定循环任务所遵循的轨迹。我们表明，将关节轨迹和驱动参数都作为优化变量的一般问题，可以转化为一个更简单的问题，即优化仅涉及关节轨迹。报告了对全驱动和欠驱动柔顺机器人的模拟，以证明该方法的有效性。尽管刚度优化方法本质上是解析的，但它可直接应用于模型未知的现有系统。介绍了一个在具有串联弹性驱动器的跳跃机器人原型上的无模型实验应用。
In this paper, we study the role of soft actuation in the reduction of the energy cost for mechanical systems that perform cyclic tasks. The objective is to determine the optimal stiffness value and spring pre-load such that a given cost functional is minimized. For the analysis, we consider both fully actuated and underactuated mechanical systems using elastic actuators which, depending on how and where the springs are placed w.r.t. the actuator and the load, can be Series Elastic Actuators (SEAs) or Parallel Elastic Actuators (PEAs). The energy consumption depends not only on the actuation parameters but also on the trajectories followed to perform a given cyclic task. We show that the general problem in which both joint trajectories and actuation parameters are the optimization variables, can be cast as a simpler problem in which optimization regards only joint trajectories. Simulations of fully actuated and underactuted compliant robots are reported to demonstrate the effectiveness of the method. Although the stiffness optimization method is analytical in nature, it is directly applicable to existing systems whose model is unknown. A model-free experimental application on a prototype of a hopping robot with SEA is presented.