Mid-Air Haptic Control Point Blending for Coherent Acoustic Fields
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Solution Overview
Problem
Existing mid-air haptic systems face issues with temporal coherence in acoustic fields due to abrupt changes in control points, leading to unwanted noise and interference, and require large numbers of transducers for effective energy deposition, while hand tracking inaccuracies cause misalignment and inefficiency in haptic feedback.
Innovation Solution
A method involving control point blending and neural networks is employed to smoothly integrate new control points into the acoustic field, using opacity coefficients and continuous field modeling to maintain coherence, and a neural network to approximate acoustic properties efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If new control points are added to the acoustic field, then the control flexibility and functionality are improved, but temporal coherence is disrupted causing audible noise and popping artifacts
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the acoustic field state before control points are added. When a new control point is introduced, the system retrieves the previous state and uses it as a starting point for gradual transition, preventing abrupt changes that cause audible noise. This preparatory measure ensures temporal coherence is maintained during dynamic control point manipulation.
Solution Approach 2:
The system implements dynamics by enabling smooth transitions between different acoustic field configurations through gradual interpolation. When control points are added or modified, the acoustic field parameters are dynamically adjusted over multiple time steps rather than instantaneously, allowing the field to evolve continuously and maintain temporal coherence while adapting to new control requirements.
2Measurement precision
If control points are moved or modified, then the haptic feedback accuracy is improved, but discontinuities in wave coalescence occur generating audible sound
Solution Approach 1:
The patent ensures continuity of useful action by maintaining continuous acoustic field evolution during control point movements. The system uses temporal interpolation to bridge successive field states, ensuring that wave coalescence patterns change smoothly rather than discontinuously. This continuous transition prevents the generation of audible noise while preserving accurate haptic feedback positioning.
Solution Approach 2:
The patent introduces an intermediary mechanism in the form of temporal interpolation that mediates between successive acoustic field states. When control points are moved, the interpolation algorithm generates intermediate field configurations that smoothly connect the initial and final states, preventing abrupt discontinuities in wave coalescence that would otherwise generate audible sound.
3Force
If focused high acoustic pressure control points are created, then the haptic feedback intensity is improved, but energy deposition density increases requiring more transducers
Solution Approach 1:
The patent applies local quality by concentrating acoustic energy precisely at the focal point where haptic feedback is needed, while maintaining lower energy levels in surrounding regions. Through phased array control and constructive interference techniques, the system achieves high localized pressure at the target location without proportionally increasing the total number of transducers required, as energy is efficiently directed only where needed rather than distributed uniformly.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces noise and interference, minimizes transducer requirements, and maintains accurate haptic feedback despite hand tracking inaccuracies, enhancing user experience and efficiency in mid-air haptic systems.
Implementation Method 1
When a focused high acoustic pressure control point is created the ultrasonic transducers interfere constructively at the focus point given
Implementation Method 2
sound-from-ultrasound systems
Implementation Method 3
haptic feedback in mid-air
Data Source
AI summary
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. Further, to resolve the misalignment of expected and realized output of the mid-air haptic array, interactable objects are subdivided into customizable, uniform, intersection “regions” that are then used to compute a volume of 3D positions in which the haptic focal point is then moved between. Positions can be produced and assigned in different ways, and volumes can be produced from any object as long as they have their regions pre-computed. Rather than directly targeting the hand of the user, the virtual intersection of the hand are used and these regions create a generally larger volume in which mid-air haptics can be produced.