【作者】 刘欣；

【导师】 王瀚； 国狄非；

【作者基本信息】 天津大学 ， 电子信息， 2023， 硕士

【摘要】 非接触式的空中触觉反馈技术可以给使用者提供一种自然和无束缚的人机交互体验,是近年来虚拟和增强现实领域的重要研究方向之一。当前,非接触式触觉反馈主要依靠空气耦合超声换能器构成阵列,通过控制阵元驱动信号产生聚焦声束,利用焦点处较高的声辐射压强实现人体的触觉感知。当渲染一个较大的触觉区域时(例如人类手掌的面积),可通过在反馈目标区域上生成多个反馈焦点,或者控制单一反馈焦点的移动轨迹产生面状触觉。以上方案虽然有效,但需要复杂的算法来同时控制每个阵元换能器驱动信号的幅值和相位,并对硬件系统产生较大的功耗负担。同时,文献中普遍指出基于空气耦合超声相控阵的触觉反馈装置,在工作时存在较为明显的低频噪声,影响使用体验。针对以上难题,本文主要研究基于空气耦合超声相控阵的非接触式触觉反馈实现方法,重点探索可渲染较大触觉反馈面积的高效波束产生与调控方案,并探索降低驱动系统中换能器工作噪声的可行方法。本文首先结合人体触觉感受的生理机制和超声波在空气中传播的非线性声学性质,分析了利用超声辐射压强实现触觉反馈的物理基础和通过幅度调制与时空调制实现触觉反馈的技术原理。本文通过建立换能器阵列辐射声场的计算模型,对声场声压的空间分布进行了可视化仿真,并以此作为设计触觉反馈方案的基础。在硬件系统方面,本文以现场可编程门阵列(field programmable gate array,FPGA)器件作为核心设计多通道信号相位控制电路,并结合功率开关电路和换能器探头阵列设计,搭建相控阵驱动系统作为实现触觉反馈的硬件基础。在触觉实现方面,本文在实现单点触觉反馈的基础上,提出利用时分复用方法实现多点触觉反馈的可行方案。同时,本文创新性地提出了一种利用声涡旋实现较大面积触觉反馈的方案。研究中通过仿真分析了涡旋波束的声压分布特性,利用波束在垂直传播轴向的截面可产生具有较大尺寸高声压区域的物理特征,直接渲染出较大面积的触觉反馈平面,相比通过控制触觉反馈点来实现面状区域触觉的常规方法,无需复杂的调制算法,并可提高系统的能量效率。本文通过计算仿真和实验测量,对比验证了所提出方案的有效性,同时通过测量确定了可产生较高触觉反馈力的换能器阵列驱动系统信号调制方法。此外,本文还提出了基于正弦调制的系统低频噪声消除方法,并设计了基于FPGA和模拟开关电路的触觉反馈实现方案,通过测量验证了所提出的方法能够在实现触觉反馈的同时,有效减小换能器工作时产生的噪声。更多还原

【Abstract】 Non-contact aerial haptic feedback technology provides users with a natural and unrestricted human-computer interaction experience,and it is one of important research directions in the fields of virtual and augmented reality in recent years.Currently,non-contact tactile feedback mainly relies on an array of air-coupled ultrasonic transducers to generate focused sound beams by controlling the driving signals of each array element and utilizes the higher sound radiation pressure at the focus to achieve human tactile perception.When rendering a larger tactile area(such as the area of the human palm),it is possible to generate multiple feedback foci in the feedback target area or control the moving trajectory of a single feedback focus to produce a planar tactile sensation.Although these approaches are effective,they require complex algorithms to control the amplitude and phase of the driving signals of each transducer element simultaneously and impose a large power consumption burden on the hardware system.At the same time,it is generally pointed out in the literature that tactile feedback devices based on air-coupled ultrasonic phased arrays have significant low-frequency noise during operation,which affects the user experience.To address the aforementioned challenges,this thesis mainly investigates the implementation method of non-contact tactile feedback based on air-coupled ultrasonic phased arrays,focusing on exploring efficient beams generation and control schemes that can render larger tactile feedback areas,and exploring feasible methods to reduce the working noise of transducers in the driving system.This thesis firstly combines the physiological mechanisms of human tactile perception and the nonlinear acoustic properties of ultrasound propagation in air,analyzes the physical basis of using ultrasonic radiation pressure to achieve tactile feedback,and the technical principles of achieving tactile feedback through amplitude modulation and spatiotemporal modulation.A computational model of the radiated sound field of the transducer array is established,and the spatial distribution of sound pressure in the sound field is visualized through simulation,which serves as the basis for designing tactile feedback schemes.In terms of hardware system,this thesis employs field programmable gate array(FPGA)as the core device to design a multi-channel signal phase control circuit for the hardware system.The circuit is combined with power switching circuits and a transducer array to construct a phased array driving system as the hardware foundation for realizing tactile feedback.In terms of haptic implementation,this thesis proposes a feasible solution for multi-point haptic feedback using time-division multiplexing based on the foundation of single-point haptic feedback.Additionally,this thesis presents an innovative approach that utilizes acoustic vortices to achieve haptic feedback over a larger area.In this study,the pressure distribution characteristics of vortex beams were analyzed by simulation,and it was found that the beam can produce physical characteristics with large high-pressure regions on the cross section perpendicular to the propagation axis.This characteristic can be directly used to render a large area tactile feedback plane without the need for complex modulation algorithms,and improve the energy efficiency of the system compared to the conventional method of controlling tactile feedback points to achieve tactile feedback in a planar area.This thesis validates the proposed approach through computational simulations and experimental measurements,and compares its effectiveness.In addition,the signal modulation method of the transducer array driving system,which can generate relatively high tactile feedback force,is determined through measurements.In addition,this thesis proposes a low-frequency noise elimination method based on sine modulation and designs a tactile feedback implementation scheme based on FPGA and analog switch circuits.By measurements,it is verified that the proposed method can effectively reduce the noise generated by transducer working while implementing tactile feedback.更多还原