Ultrasonic Haptic Phase Control to Minimize Parametric Audio
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Solution Overview
Problem
Haptic feedback systems using ultrasound are susceptible to unwanted parametric audio due to intermodulation distortion and high-Q resonant systems have slow impulse responses, leading to inefficiencies in amplitude control.
Innovation Solution
Methods to manipulate haptic curves using spatiotemporal modulation by adjusting the phase function and path parameterization to minimize unwanted audio, including direct radius smoothing, temporally smooth point distributions, spatial filtering, and Fourier series approximations, along with feed-forward input generation via linear algebra to control transducer activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional amplitude modulation is used to create haptic feedback, then haptic sensation is produced, but unwanted parametric audio and intermodulation distortion are generated
Solution Approach 1:
The patent changes the modulation parameter from amplitude modulation to phase modulation. By modulating the phase of the ultrasonic carrier wave according to the haptic curve parameterization, the system produces the desired haptic sensation while avoiding the generation of difference tones and intermodulation distortion that occur with amplitude modulation.
Solution Approach 2:
The patent substitutes the traditional amplitude-based mechanical modulation approach with a phase-based modulation approach. This replacement fundamentally changes how the ultrasonic field is modulated to achieve haptic effects, eliminating the harmful parametric audio generation mechanism while preserving the useful haptic feedback function.
2Adaptability or versatility
If spatiotemporal modulation is used to move focal points, then haptic effects are created, but multiple side bands and intermodulation distortion occur
Solution Approach 1:
The patent applies phase modulation instead of amplitude modulation in the spatiotemporal focusing approach. By encoding the haptic curve information in the phase of each transducer element rather than in amplitude variations, the system achieves versatile haptic effect creation while minimizing the generation of unwanted side bands and intermodulation products.
3Measurement precision
If high-Q resonant systems are used for transducer operation, then frequency selectivity is improved, but impulse response time increases
Solution Approach 1:
The patent uses feed-forward control that anticipates the desired output and pre-calculates the necessary drive conditions. By using the known impulse response characteristics of the high-Q resonant system, the control algorithm compensates for the slow response in advance, allowing the system to reach the desired state faster than would be possible with traditional reactive control approaches.
Solution Approach 2:
The patent implements dynamic control that adapts the drive conditions based on the system's resonant characteristics. By continuously adjusting the phase and amplitude of each transducer element according to the desired haptic curve and the system's impulse response, the control system optimizes the trade-off between frequency selectivity and response time.
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
Reduces unwanted audio interference and improves haptic feedback accuracy by optimizing phase functions and transducer control, allowing for precise and efficient haptic curve reproduction.
Implementation Method 1
producing an acoustic field from a transducer array
Implementation Method 2
the nonlinearity of soundwaves in air can create audible sound. This mixing takes the form of difference tones (intermodulation distortion)
Implementation Method 3
Haptic curve reproduction involves the rapid translation of focal points in an ultrasonic phased array configuration
Implementation Method 4
an ultrasonic phased array configuration
Data Source
AI summary
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.