Mid-Air Haptic Calibration With Spiral Arrays to Reduce Ghost Fields
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Solution Overview
Problem
Existing haptic systems face challenges in controlling acoustic fields due to erroneous local maxima and ghost phenomena, which interfere with mid-air interactions, and manual calibration methods are prone to human error.
Innovation Solution
Implementing transducer arrays arranged in phyllotactic spiral patterns and using computational automation to optimize placement, combined with levitation fiducials for automated calibration, to minimize secondary maxima and enhance precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If transducer elements are arranged in traditional arrays, then the system is easy to manufacture, but erroneous local maxima and ghost phenomena occur in the acoustic field
Solution Approach 1:
The patent applies asymmetry by arranging transducer elements in a spiral pattern rather than traditional symmetric grid arrays. This asymmetric configuration disrupts the formation of regular interference patterns, thereby minimizing erroneous local maxima and ghost phenomena in the acoustic field while remaining manufacturable
Solution Approach 2:
The patent implements preliminary action through automated calibration procedures that pre-establish the correspondence between acoustic field coordinate space and sensor coordinate space before actual haptic interactions occur. This pre-calibration using fiducial markers eliminates the need for manual calibration and ensures accurate positioning from the start
2Manufacturing precision
If ideal transducer configurations are used, then acoustic field control is optimized, but physical manufacturing constraints prevent achievement
Solution Approach 1:
The patent applies parameter changes by modifying the transducer arrangement from ideal theoretical configurations to practical spiral patterns that account for manufacturing constraints. The spiral configuration maintains the essential benefit of minimizing erroneous maxima while being adaptable to real-world fabrication limitations and component tolerances
3Measurement precision
If manual calibration is performed, then correspondence between coordinate spaces is established, but human error and intervention are introduced
Solution Approach 1:
The patent implements self-service through automated calibration systems that use fiducial markers to automatically establish the correspondence between acoustic field coordinate space and sensor coordinate space. The system calibrates itself without human intervention, eliminating manual errors and ensuring consistent, repeatable calibration results across different devices and operators
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
The phyllotactic spiral transducer arrays reduce noise and interference, enabling precise mid-air haptic feedback with improved efficiency and reduced human error in calibration.
Implementation Method 1
Acoustic radiation pressure may be used to levitate one or more fiducials above the array, which may then be used for calibration of the array and/or sensor.
Implementation Method 2
Acoustic radiation pressure can be used to provide haptic feedback in mid-air
Data Source
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AI summary
A system providing various improved calibration techniques for haptic feedback is described. An acoustic field is defined by one or more control points in a space within which the acoustic field may exist. Each control point is assigned an amplitude value equating to a desired amplitude of the acoustic field at the control point. Because complete control of space is not possible, controlling the acoustic field at given points yields erroneous local maxima in the acoustic field levels at other related positions. In relation to mid-air haptic feedback, these can interfere in interactions with the space by creating secondary effects and ghost phenomena that can be felt outside the interaction area. The level and nature of the secondary maxima in the acoustic field is determined by how the space is controlled. By arranging the transducer elements in different ways, unwanted effects on the acoustic field can be limited and controlled.