| Micromanipulation technology has confronted new challenges as research in the microscopic field continues to deepen.The traditional contact micromanipulation technology is constrained by the disadvantages of surface force adhesion,uneven stress,and contact contamination,which is challenging to adapt to the increasing demand for micromanipulation.For this reason,contactless micromanipulation technology has emerged.Acoustic levitation manipulation is a contactless micromanipulation technology that utilizes the acoustic radiation force generated by the dynamic acoustic field to realize the levitation and manipulation of tiny objects.Compared with other contactless micromanipulation methods such as optical tweezers,acoustic levitation manipulation has no requirements for controlled objects such as electrical conductivity,magnetic conductivity,or light transmission and is biocompatible,flexible,and widely applicable.Therefore,acoustic levitation manipulation has become an up-and-coming contactless micromanipulation technology and is showing broad application prospects in the fields of life sciences,materials chemistry,droplet dynamics,and other cutting-edge scientific research,as well as high-end manufacturing.With the development of piezoelectric transducer technology and electronic information technology,ultrasonic phased arrays(UPAs)are widely used in acoustic levitation manipulation,which can realize flexible modulation of the acoustic field by controlling the phase delay of each element,providing more possibilities for acoustic levitation manipulation,and currently becoming the mainstream way to realize acoustic levitation manipulation.In the past decade,the research on acoustic levitation manipulation based on the UPAs has made significant progress.However,the nonlinear and strong coupling characteristics of the acoustic levitation manipulation system make its application in practical diversified scenarios still face many challenges:1.How to construct a specific morphology of levitation acoustic field according to the needs of diversified scenarios;2.How to inhibit the uncontrolled spin and oscillations of levitated objects with diversified shapes;3.How to characterize the dynamics of the levitated objects and to predict their dynamic behaviors;4.How to realize the high-performance manipulation of the levitated objects.Focusing on the above problems,this paper is based on the UPAs,with acoustically levitated objects as the controlled objects and the modulation of the morphology and position of the levitated acoustic field as the means of control,to research the acoustic field construction and the motion control method of levitated objects oriented to diversified application scenarios.The main content and contributions are as follows:1.A data-driven framework for phase inversion of the levitated acoustic field is proposed to address the inability of traditional methods to construct the desired morphology of the sound field.We analyze the characteristics of the levitated acoustic field and the data-driven requirements and derive the parameters describing the levitated acoustic field;establish the sound field simulation system based on MATLAB and complete the generation of the data set;and propose the phase inversion method based on the modified U-Net network to realize the construction of the customized morphology of the levitated acoustic field.2.For the weak levitation force of the array levitator in the contactless microreactor scenario,we analyze the influence of the array arrangement on the levitation force and propose the optimization method of the arrangement in the spherical ring,which improves the levitation ability;for joint control of position and attitude and the uncontrolled spin due to the various shapes of the levitated samples,we establish the transfer function model of the acoustic trap-levitated object and analyze the mechanism of levitation and manipulation,as well as the dynamic characteristics of the system.and the concept of standing wave tweezers and its construction method are put forward,which can effectively inhibit oscillations and spins of levitated objects,and realize joint control of position and attitude;finally,a universal hardware platform for UPAs is designed,and the validity of the proposed model and method is verified through simulation and physical experiments.3.Aiming at the current problem of poor stability and low efficiency of contactless transportation,the problem is described as a time-optimal trajectory planning problem under kinematic constraints with start and end states determined;the constraints in acoustic manipulation trajectory motion are analyzed,and a gravity-acoustic trap morphology step-size constraint theory is proposed;for the trajectory planning problem of a levitated object,an interpolation-based transportation trajectory generation method,a time-optimal optimization model and a trajectory planning method based on the whale optimization algorithm are proposed;finally,the correctness of the proposed constraint theory is verified through simulations and in-kind experiments,and it is demonstrated that the proposed method can improve the stability and efficiency of the transport efficiently.4.Targeting the problem of large trajectory tracking error of levitated particles in application scenarios such as acoustic volumetric display,around the acoustic trap trajectory optimization problem,a mechanism-data hybrid model of the acoustic trap-levitated microparticle is established to achieve the description and prediction of the dynamic behaviors of levitated objects;a particle swarm-based rolling prediction acoustic trap trajectory optimization method is proposed,and a single-step optimization model and a global optimization model are designed,which are combined with the particle swarm algorithm to solve the model and obtain the optimized acoustic trap trajectory.Simulations and physical experiments show that the proposed method outperforms the traditional method in terms of maximum absolute error and root mean square error.To summarize,this paper is oriented to the practical application scenarios in multiple fields and types,focusing on the construction of the levitated sound field and motion control of levitated objects,with the goal of improving the acoustic levitation manipulation performance and carrying out the research on acoustic levitation manipulation mechanism,description and construction of levitated sound field,and the position and motion control methods for the application scenarios.The goal is to provide high-performance contactless micro-manipulation solutions for frontier scientific research and high-end manufacturing and to promote the development and application of acoustic micro-manipulation technology. |
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