Controlling Acoustic Traps for the Contactless Handling of Objects (CATCH)

通过声悬浮方法对液滴和精细固体物体的非接触操纵在化学、药学、生物学和微电子学中具有许多应用。在过去的几年里，声悬浮的新进展使悬浮物体在3D中的受控运动成为可能，但是不期望的振荡可能会阻碍某些需要高运动精度的应用。为了提高操作速度和减少不必要的振荡，我们将研究开环和闭环控制系统在声悬浮中的应用。这项调查将结合德国集团在控制工程方面的专业知识和巴西集团在声悬浮系统方面的专业知识进行。在这项研究中，液体和固体物体将悬浮和操纵的声悬浮系统组成的相控阵低功率超声换能器。控制工程方法，如前馈控制和H ∞控制，将被应用到既减少振荡，提高操纵速度的悬浮物体。本研究将分为三个部分。我们将开始我们的研究，设计一个合适的声悬浮系统，并建立相应的白盒模型，其参数将实验确定的系统识别方法。随后，我们采用创建的模型来开发一个开环控制系统来操纵固体和液体。这些结果将用于开发基于摄像机的真实的时间闭环位置控制，以处理模型误差和过程干扰，如声流。控制过程的改进将使用诸如绝对位置误差、最大速度和振荡幅度的标准来评估。最后，新的悬浮系统将安装在小角X射线散射（SAXS）设备中，以便在半空中操纵，混合和分析悬浮物质。

The contactless manipulation of liquid drops and delicate solid objects by acoustic levitation methods has numerous applications in chemistry, pharmacy, biology, and microelectronics. Over the last years, new advances in acoustic levitation enabled the controlled motion of levitated objects in 3D, but undesired oscillations may hinder certain applications that require a high precision in motion. To increase the manipulation speed and reduce undesired oscillations, we will investigate the application of open-loop and closed-loop control systems in the context of acoustic levitation. This investigation will be conducted by combining the German group’s expertise in control engineering with the Brazilian group’s expertise in acoustic levitation systems. In this study, liquid and solid objects will be levitated and manipulated by an acoustic levitation system consisting of a phased array of low power ultrasonic transducers. Control engineering methods, such as feed forward control and H-infinity control, will be applied to both reduce the oscillation and increase the manipulation speed of the levitated object. This investigation will be divided into three parts. We will start our study by designing an appropriate acoustic levitation system and creating a corresponding white-box model, which parameters will be experimentally determined by system identification methods. Subsequently, we employ the created model to develop an open-loop control system to manipulate solids and liquids. These results will be utilized for the development of a camera-based real time closed-loop position control to handle model errors and process disturbances such as acoustic streaming. The improvements of the controlled process will be evaluated using criteria such as absolute position error, maximum speed and oscillation amplitude. Finally, the new levitation system will be installed in a Small-Angle X-ray Scattering (SAXS) equipment in order to manipulate, mix, and analyze levitating substances in mid-air.