[论文解读] A rotational traveling wave based levitation device - Modeling, design, and control

Ran Gabai, Dotan Ilssar+3 more|arXiv (Cornell University)|Aug 24, 2016

Microfluidic and Bio-sensing Technologies参考文献 19被引用 3

一句话总结

本文提出了一种利用振动环产生超声驻波和行波，对声悬浮物体实现非接触旋转操控的系统。通过闭环系统控制这两种波的幅比，利用气膜中的剪切力精确调控旋转扭矩，实现了快速且精准的角位置控制，且采用简化的单参数控制方法。

ABSTRACT

Described is a device acting on an acoustically levitated object by manipulating the pressure and flow of a thin layer of air such that its rotation can be precisely controlled without mechanical contact. Virtual work analysis assists in simplifying the multi-actuator control problem into a problem governed by a controllable parameter. Actuation is done with a vibrating ring capable of producing ultrasonic standing and traveling waves, creating the acoustic excitation that affects the pressure in a thin, intermediate layer of gas. A distinctive vibration pattern is required to generate the temporal and spatial pressure field of the squeezed air layer that gives rise to both acoustic levitation force and rotational torque. Described are the physical and design development stages leading to an optimized structure, all followed by verifying and dynamics-calibration experiments. Moreover, by precisely controlling the ratio of standing and traveling waves in a closed-loop, one can affect the shear forces applied by the squeezed air layer, thus creating a non-contacting manipulation mechanism. An over-actuated set-up is converted via an algebraic transformation, into a simplified single control-parameter problem. The transformation ties the standing waves ratio, and hence the rotational torque, to the amplitudes and phases of the actuators. This arrangement leads to an effective closed loop methodology that was implemented experimentally showing good performance and exhibiting rapid angular positioning.

研究动机与目标

• 开发一种非机械方法，用于控制声悬浮物体的旋转。
• 解决声悬浮系统中多执行器控制的复杂性问题。
• 通过将过驱动执行器输入转换为单一可控参数，简化控制问题。
• 在无物理接触的情况下，实现对悬浮物体的精确、快速角位置控制。

提出的方法

• 采用可同时产生超声驻波和行波的振动环。
• 通过虚功分析，将多执行器控制问题简化为单一可控参数。
• 应用代数变换，建立执行器振幅与相位到驻波与行波幅比的映射关系。
• 采用闭环控制动态调节波幅比，调节气膜中的剪切力。
• 通过物理和动力学校准实验，设计并优化机械结构。
• 利用薄中间气体层，通过压力与流动变化同时产生悬浮力和旋转扭矩。

实验结果

研究问题

• RQ1 如何在无机械接触的情况下精确控制悬浮物体的旋转扭矩？
• RQ2 驻波与行波的最优配置是什么，以在气膜中产生可调控的剪切力？
• RQ3 能否将复杂的多执行器系统简化为单一控制参数以实现有效操控？
• RQ4 驻波与行波的幅比如何影响产生的扭矩及角位置控制性能？
• RQ5 哪些实验验证结果能够证明该控制方法的有效性与响应速度？

主要发现

• 该系统成功通过气膜中可控剪切力实现对悬浮物体的精确非接触角位置控制。
• 闭环控制方法实现了快速响应与精确角位置控制，实验已验证其有效性。
• 代数变换有效将过驱动系统简化为单一控制参数，显著简化了实现过程。
• 通过调节驻波与行波的幅比，设备实现了有效操控，直接调控旋转扭矩。
• 动力学校准与实验验证证实了模型的准确性及系统的鲁棒性能。