Abstract: To resolve an issue related to the calibration of optical cameras in transducer-based mid-air haptic systems, the magnification of the motion induced on an optical camera by an acoustic field modulated at specific frequencies reveals very small temporal variations in video frames. This quantized distortion is used to compare different acoustic fields and to solve the calibration problem in an automatized manner. Further, mechanical resonators may be excited by ultrasound when it is modulated at the resonant frequency. When enough energy is transferred and when operating at the correct frequency, a user in contact with the device can feel vibration near areas of largest displacement. This effect can be exploited to create devices which can produce haptic feedback while not carrying a battery or exciter when in the presence of an ultrasonic source.

Abstract: An acoustic matching structure is used to increase the power radiated from a transducing element with a higher impedance into a surrounding acoustic medium with a lower acoustic impedance. The acoustic matching structure consists of a thin, substantially planar cavity bounded by a two end walls and a side wall. The end walls of the cavity are formed by a blocking plate wall and a transducing element wall separated by a short distance (less than one quarter of the wavelength of acoustic waves in the surrounding medium at the operating frequency). The end walls and side wall bound a cavity with diameter approximately equal to half of the wavelength of acoustic waves in the surrounding medium. In operation, a transducing element generates acoustic oscillations in the fluid in the cavity.

Abstract: A digital signal generation assumes that a base frequency (the frequency with which the primitive phase angles are specified relative to) is equal to the carrier frequency for all relevant times. But this causes errors in the digital signals output to each array element transducer. Thus, it is necessary for the development of a signal generation system that is capable of producing a digital signal using the free selection of amplitude and phase. This is used to produce a substantially error-free signal that preserves the amplitude and phase relative to a constant base frequency while allowing the carrier frequency to vary.

Abstract: Defining critical spacing is necessary for steering of parametric audio. Comparing steering measurements both with and without a waveguide leads to a conclusion that the diffuse phyllotactic grating lobe contributes audio and is to blame for poor steering. In addition, the waveguide needs to function with correct phase offsets to achieve the steering required for performance. Arranging tubes so that the array configuration changes from rectilinear to another distribution is useful when the waveguide is short of critical spacing or constrained for space. Array designs may also capitalize on rectilinear transducer design while having the benefits of a transducer tiling that has irrational spacing to promote the spread of grating lobe energy.

Abstract: A method for specifying desired quantities of the energy flux of the combined waves of acoustic radiation pressure to apply producing a mid-air haptic pushing force, which has the effect of simultaneously reducing the harmonic distortion present is described. Further, a method for communicating only the summaries of acoustic field contributions at the required locations in the form of summed portions of the relatively small matrix whose row and column count depend only on the control point count is described. Further, phased arrays of ultrasonic speakers can produce a relatively large amount of acoustic energy which is usually directed in a specific direction or focused to a particular point depending on the application of the array. Further, to allow the system to be driven more strongly than usual, the complex-valued linear system that governs the drive signal to each control point is solved twice.

Abstract: Producing multiple independent fields from many phased acoustic transducers represents a difficult computational problem. By first dividing up each field to its own group of transducers and then treating each group as an element with adjustable phase, one can minimize the field-to-field interference through a power iteration solution. These solutions can be further refined by including tracking information from users in the space and how they shadow or reflect the acoustic fields.

Abstract: Disclosed are methods to manipulate a given parametrized haptic curve in order to yield a smooth phase function for each acoustic transducer which minimizes unwanted parametric audio. Further, the impulse response of a haptic system describes the behavior of the system over time and can be convolved with a given input to simulate a response to that input. To produce a specific response, a deconvolution with the impulse response is necessary to generate an input.

Abstract: A digital signal generation assumes that a base frequency (the frequency with which the primitive phase angles are specified relative to) is equal to the carrier frequency for all relevant times. But this causes errors in the digital signals output to each array element transducer. Thus, it is necessary for the development of a signal generation system that is capable of producing a digital signal using the free selection of amplitude and phase. This is used to produce a substantially error-free signal that preserves the amplitude and phase relative to a constant base frequency while allowing the carrier frequency to vary.

Abstract: A phased array of ultrasonic transducers may create arbitrary fields that can be utilized to manipulate fluids. This includes the translation of drops on smooth surfaces as well speeding the evaporation of fluids on wetted hands. Proposed herein is the use airborne ultrasound focused to the surface of the hand. The risk is that coupling directly into the bulk of the hand may cause damage to the cellular material through heating, mechanical stress, or cavitation. Using a phased array, the focus may be moved around, thus preventing acoustic energy from lingering too long on one particular position of the hand. While some signaling may penetrate into the hand, most of the energy (99.9%) is reflected. Also disclosed are methods to couple just to the wetted surface of the hand.

Abstract: Strategies for managing an “always on” solution for volumes with enhanced interactive haptic feedback and its implications are addressed. Ultrasound transducer arrays may be mounted on a person (such as on a head mounted display or other wearable accessory). This array may utilize some form of 6 degree-of-freedom tracking for both the body and hands of the user. The arrays coordinate to project focused acoustic pressure at specific locations on moving hands such that a touch sensation is simulated. Using wearable microphones, the ultrasonic signal reflected and transmitted into the body can be used for hand and gesture tracking.

Abstract: Defining critical spacing is necessary for steering of parametric audio. Comparing steering measurements both with and without a waveguide leads to a conclusion that the diffuse phyllotactic grating lobe contributes audio and is to blame for poor steering. In addition, the waveguide needs to function with correct phase offsets to achieve the steering required for performance. Arranging tubes so that the array configuration changes from rectilinear to another distribution is useful when the waveguide is short of critical spacing or constrained for space. Array designs may also capitalize on rectilinear transducer design while having the benefits of a transducer tiling that has irrational spacing to promote the spread of grating lobe energy.

Abstract: Disclosed are methods to manipulate a given parametrized haptic curve in order to yield a smooth phase function for each acoustic transducer which minimizes unwanted parametric audio. Further, the impulse response of a haptic system describes the behavior of the system over time and can be convolved with a given input to simulate a response to that input. To produce a specific response, a deconvolution with the impulse response is necessary to generate an input.

Abstract: Mid-air ultrasonic haptic devices operate by manipulating an acoustic field to produce a haptic effect on a user. Addressing mid-air haptic devices which abstracts the most basic acoustic fundamental from that of a point to a “primitive” provides tools to adjust shape, location, and amplitude. A primitive can be designed to provide a haptic effect at the location targeted, removing the requirement of the designer needing to understand methods to create a haptic sensation. Further, a control scheme for a set of dynamic acoustic phased-array solvers is presented which enables a distributed system to compensate for unwanted time-of-flight artifacts at low cost. This is achieved by recursively subdividing the system into subtrees of phased-array nodes whose output can be estimated and the desired field drive distributed amongst the nodes.

Abstract: Estimating the field strength from an ultrasonic phased array can be done by summing the contribution of each transducer to the point of interest. Since this contribution is already calculated when creating a converging spherical wave, it can be reused to add a virtual microphone to the system. By monitoring this microphone and moving it along with new focus points, a robust system of field estimates and regulation may be established.

Abstract: An acoustic matching structure is used to increase the power radiated from a transducing element with a higher impedance into a surrounding acoustic medium with a lower acoustic impedance. The acoustic matching structure consists of a thin, substantially planar cavity bounded by a two end walls and a side wall. The end walls of the cavity are formed by a blocking plate wall and a transducing element wall separated by a short distance (less than one quarter of the wavelength of acoustic waves in the surrounding medium at the operating frequency). The end walls and side wall bound a cavity with diameter approximately equal to half of the wavelength of acoustic waves in the surrounding medium. In operation, a transducing element generates acoustic oscillations in the fluid in the cavity.

Abstract: To resolve an issue related to the calibration of optical cameras in transducer-based mid-air haptic systems, the magnification of the motion induced on an optical camera by an acoustic field modulated at specific frequencies reveals very small temporal variations in video frames. This quantized distortion is used to compare different acoustic fields and to solve the calibration problem in an automatized manner. Further, mechanical resonators may be excited by ultrasound when it is modulated at the resonant frequency. When enough energy is transferred and when operating at the correct frequency, a user in contact with the device can feel vibration near areas of largest displacement. This effect can be exploited to create devices which can produce haptic feedback while not carrying a battery or exciter when in the presence of an ultrasonic source.

Abstract: A method for blending new control points into the field is described. A more costly but conceptually simpler method, measuring the extant field and recreating a copy of that field interpolated with the actually desired value at a new control point is first described. Further, traditionally predicting the output of phased array systems involves taking each element and evaluating its contribution to the field. When focusing phased arrays, predicting the output and the fringing field is necessary for multipoint focusing and acoustic cloaking applications. In the limit of a large enough number of discrete transducer elements, the evaluation of a single approximation will inevitably outperform even a linear summation over the linear acoustic properties of the elements.

Abstract: Estimating the field strength from an ultrasonic phased array can be done by summing the contribution of each transducer to the point of interest. Since this contribution is already calculated when creating a converging spherical wave, it can be reused to add a virtual microphone to the system. By monitoring this microphone and moving it along with new focus points, a robust system of field estimates and regulation may be established.

Abstract: An acoustic matching structure is used to increase the power radiated from a transducing element with a higher impedance into a surrounding acoustic medium with a lower acoustic impedance. The acoustic matching structure consists of a thin, substantially planar cavity bounded by a two end walls and a side wall. The end walls of the cavity are formed by a blocking plate wall and a transducing element wall separated by a short distance (less than one quarter of the wavelength of acoustic waves in the surrounding medium at the operating frequency). The end walls and side wall bound a cavity with diameter approximately equal to half of the wavelength of acoustic waves in the surrounding medium. In operation, a transducing element generates acoustic oscillations in the fluid in the cavity.

Abstract: To resolve an issue related to the calibration of optical cameras in transducer-based mid-air haptic systems, the magnification of the motion induced on an optical camera by an acoustic field modulated at specific frequencies reveals very small temporal variations in video frames. This quantized distortion is used to compare different acoustic fields and to solve the calibration problem in an automatized manner. Further, mechanical resonators may be excited by ultrasound when it is modulated at the resonant frequency. When enough energy is transferred and when operating at the correct frequency, a user in contact with the device can feel vibration near areas of largest displacement. This effect can be exploited to create devices which can produce haptic feedback while not carrying a battery or exciter when in the presence of an ultrasonic source.