Ultrasonic Transducer Array Calibration for Haptic Feedback
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Solution Overview
Problem
Current haptic-based systems face challenges in efficiently controlling and calibrating acoustic fields for precise haptic feedback, particularly in managing large volumes and real-time updates, and in synchronizing multiple ultrasonic transducer arrays for accurate positioning and feedback.
Innovation Solution
The method involves defining control points with known spatial relationships, using eigenproblems to optimize phase and amplitude relationships, and employing virtual transducers to pre-compute look-up tables, along with time difference of arrival algorithms for array synchronization, and allowing frequency modulation for focusing while maintaining haptic feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional methods are used to control acoustic fields, then system simplicity is maintained, but control speed and predictability deteriorate when managing large volumes and real-time updates
Solution Approach 1:
The system pre-computes look-up tables containing amplitude and phase information for virtual transducers before runtime. This preliminary computation enables fast retrieval and application during real-time operation, achieving high control speed without complex real-time calculations
Solution Approach 2:
The patent uses virtual transducers that are computational copies of physical transducers. These virtual transducers simulate the acoustic field behavior and pre-compute control parameters, allowing the system to manage complex acoustic fields without directly computing every physical transducer's parameters in real-time
2Area of stationary object
If the number of control points is increased to cover larger acoustic fields, then field coverage is improved, but computation time and system complexity increase
Solution Approach 1:
The acoustic field is divided into multiple control points with known spatial relationships. Virtual transducers are assigned to these control points, and look-up tables are pre-computed for each control point. This segmentation allows the system to manage large fields by breaking them into smaller, pre-computed units
Solution Approach 2:
Look-up tables for amplitude and phase are pre-computed for all control points before runtime. This preliminary computation stores the results of complex acoustic calculations, enabling the system to support a high number of control points across large fields without increasing real-time computation time
3Measurement precision
If multiple ultrasonic transducer arrays are used for positioning and feedback, then positioning accuracy and haptic feedback quality improve, but synchronization difficulty and system complexity increase
Solution Approach 1:
The system uses time difference of arrival algorithms to monitor and measure the synchronization status of multiple transducer arrays. This feedback information is used to adjust and maintain precise synchronization across all arrays, ensuring accurate positioning and consistent haptic feedback
Solution Approach 2:
The transducer arrays serve multiple functions: they generate haptic feedback, enable positioning through time difference of arrival measurements, and provide synchronization reference signals. This multi-functionality reduces the need for separate dedicated components and simplifies the overall system architecture
4Manufacturing precision
If frequency modulation is applied for focusing, then haptic feedback precision is improved, but control complexity increases
Solution Approach 1:
The system modulates the frequency of ultrasonic waves to create focused acoustic fields. By changing the frequency parameter of the carrier wave, the system achieves precise focusing and haptic feedback control. The look-up tables store pre-computed amplitude and phase values that correspond to these frequency-modulated signals, simplifying the control process
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 enables faster and more predictable control of larger acoustic fields, supports a higher number of control points, allows real-time updates, and ensures robust haptic feedback even with multiple arrays in motion, while maintaining effective haptic sensation and object tracking.
Implementation Method 1
When used in mid-air, haptic technology works by focusing sound at an ultrasonic carrier frequency to a point or points in the space above the transducers. Then this is modulated by a waveform including low frequency content that generates the haptic sensation.
Implementation Method 2
When human skin interacts with the acoustic field, vibrations of the skin are interpreted by mechanoreceptors being excited and sending signals to the brain via the nervous system.
Implementation Method 3
The behavior of ultrasonic acoustics is a well understood approach to range finding and positioning.
Data Source
AI summary
Described is a system for producing an acoustic field from a plurality of ultrasonic transducer arrays, each of which has known relative positions and orientations. The acoustic field comprises a carrier wave and a modulated wave. The carrier wave has a plurality of modulated focal areas. A plurality of control points having a known spatial relationship relative to at least one of the plurality of ultrasonic transducer arrays is used. The plurality of ultrasonic transducer arrays are calibrated by using the relative position of each of the plurality of ultrasonic transducer arrays.