Exploiting Nonslip Wall Contacts to Position Two Particles Using the Same Control Input
Exploiting Nonslip Wall Contacts to Position Two Particles Using the Same Control Input
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DOI：
10.1109/tro.2019.2891487
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发表时间：
2019-02
影响因子：
7.8
通讯作者：
Shiva Shahrokhi;Jing-Xin Shi;B. Isichei;Aaron T. Becker
中科院分区：
文献类型：
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作者：
Shiva Shahrokhi;Jing-Xin Shi;B. Isichei;Aaron T. Becker
导向粒子提供了一种在大型机器人无法到达的区域进行靶向治疗、干预和药物输送的方法。例如，颗粒的磁致动具有不需要系绳、能够从远处操作的益处，并且在某些情况下允许用于反馈的成像（例如，MRI）。本文研究了使用均匀力（在工作空间中各处施加相同的力）的粒子位置控制。给定一个可以在三个正交方向上产生双向力的可控场，在三维（3-D）中操纵一个粒子是微不足道的。添加额外的粒子来控制会使系统欠驱动，因为状态比控制输入多。然而，体内和人工环境的壁通常具有表面粗糙度，使得颗粒不会移动，除非致动将它们拉离壁。在以前的工作中，我们证明了在具有非滑动壁接触的正方形工作空间中，两个粒子的单个二维（2-D）位置是使用全局输入可控的[1]。由于在体内的环境通常不是正方形的，本文扩展了以前的工作，所有的凸形，并显示了如何将其扩展到3-D定位的中性浮力粒子。我们调查分析这个问题的理想化的变体，防滑边界和控制输入，均匀地应用到工作区中的所有粒子。本文还实现了算法在2-D使用的硬件设置的胃肠道的启发。
Steered particles offer a method for targeted therapy, interventions, and drug delivery in regions inaccessible by large robots. For example, magnetic actuation of particles has the benefits of requiring no tethers, being able to operate from a distance, and in some cases allows imaging for feedback (e.g., MRI). This paper investigates position control of particles using uniform forces (the same force is applied everywhere in the workspace). Given a controllable field that can generate bidirectional forces in three orthogonal directions, steering one particle in three-dimensional (3-D) is trivial. Adding additional particles to steer makes the system underactuated because there are more states than control inputs. However, the walls of in vivo and artificial environments often have surface roughness such that the particles do not move unless actuation pulls them away from the wall. In the previous work, we showed that the individual two-dimensional (2-D) position of two particles is controllable using global inputs in a square workspace with nonslip wall contact [1]. Because in vivo environments are usually not square, this paper extends the previous work to all convex workspaces, and shows how this could be extended to 3-D positioning of neutrally buoyant particles. We investigate analytically an idealized variant of this problem with nonslip boundaries and control inputs that are applied uniformly to all particles in the workspace. This paper also implements the algorithms in 2-D using a hardware setup inspired by the gastrointestinal tract.