Contact-Implicit Optimization of Locomotion Trajectories for a Quadrupedal Microrobot
Contact-Implicit Optimization of Locomotion Trajectories for a Quadrupedal Microrobot
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DOI：
10.15607/rss.2018.xiv.041
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发表时间：
2018-06
期刊：
影响因子：
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通讯作者：
Neel Doshi;Kaushik Jayaram;Ben Goldberg;Zachary Manchester;R. Wood;S. Kuindersma
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作者：
Neel Doshi;Kaushik Jayaram;Ben Goldberg;Zachary Manchester;R. Wood;S. Kuindersma
腿式微型机器人的运动轨迹规划是具有挑战性的，因为它们的复杂形态，高频率的被动动力学，和不连续的接触与环境的相互作用。因此，这种研究往往是由耗时的实验方法驱动的。作为一种替代方案，我们提出了一个框架，系统地建模，规划和控制腿microrobots。我们开发了一个1.5克四足微型机器人的三维动力学模型，自由度的数量）类似于更大规模的腿式机器人。然后，我们适应最近开发的变分接触隐式轨迹优化方法来生成可行的全身运动计划，这个微型机器人，我们证明，这些计划可以跟踪简单的关节空间控制器。我们计划和执行周期性步态在多个步幅频率和各种表面上。这些步态实现了高的每周期速度，包括10.87毫米/周期的最大值，这是15%的速度比以前测量的速度为这个微型机器人。此外，我们计划并执行9.96 mm的垂直跳跃，这是微型机器人质心高度的78%。据我们所知，这是第一个端到端的演示规划和跟踪全身动态运动的毫米级腿微型机器人。
Planning locomotion trajectories for legged microrobots is challenging because of their complex morphology, high frequency passive dynamics, and discontinuous contact interactions with their environment. Consequently, such research is often driven by time-consuming experimental methods. As an alternative, we present a framework for systematically modeling, planning, and controlling legged microrobots. We develop a three-dimensional dynamic model of a 1.5 gram quadrupedal microrobot with complexity (e.g., number of degrees of freedom) similar to larger-scale legged robots. We then adapt a recently developed variational contact-implicit trajectory optimization method to generate feasible whole-body locomotion plans for this microrobot, and we demonstrate that these plans can be tracked with simple joint-space controllers. We plan and execute periodic gaits at multiple stride frequencies and on various surfaces. These gaits achieve high per-cycle velocities, including a maximum of 10.87 mm/cycle, which is 15% faster than previously measured velocities for this microrobot. Furthermore, we plan and execute a vertical jump of 9.96 mm, which is 78% of the microrobot's center-of-mass height. To the best of our knowledge, this is the first end-to-end demonstration of planning and tracking whole-body dynamic locomotion on a millimeter-scale legged microrobot.