Haptic Interface User Perception Calibration
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Solution Overview
Problem
Haptic interfaces struggle to provide uniform tactile experiences across different users due to individual variations in perception of roughness and smoothness, as each person has a unique Stevens exponent that affects how they perceive surface textures.
Innovation Solution
A method of calibrating haptic interfaces by outputting signals to simulate patterns, determining user-specific index numbers, and applying correction factors to ensure consistent haptic signaling outputs, allowing for user-specific adjustments to simulate textures and other sensations, thereby aligning perceptions across users.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If haptic interfaces use standard haptic output signals, then the device complexity is reduced, but the perception uniformity across different users deteriorates due to individual variations in Stevens exponents
Solution Approach 1:
The system performs preliminary calibration by presenting test patterns (grooves of varying widths) and measuring user responses before actual use. This preliminary action determines individual Stevens exponents and stores correction factors that will be applied automatically during subsequent haptic output, eliminating the need for complex real-time adjustments.
Solution Approach 2:
The system changes the parameter of haptic output signals by applying user-specific correction factors (Stevens exponents) to the simulated groove widths. This parameter transformation adjusts the haptic feedback to compensate for individual perception variations, ensuring uniform tactile experience across different users.
2Measurement precision
If haptic interfaces provide standardized tactile feedback, then the ease of operation is improved, but the measurement precision of individual user perception deteriorates
Solution Approach 1:
The calibration process serves the user by automatically measuring their individual perception characteristics through test patterns. The system self-adjusts based on user responses without requiring manual input or complex user involvement in the calibration process, maintaining ease of operation while achieving precise perception measurement.
3Adaptability or versatility
If haptic interfaces apply user-specific correction factors, then the perception uniformity is improved, but the device complexity increases due to calibration and data processing requirements
Solution Approach 1:
The system performs all complex signal processing and correction factor calculation during the preliminary calibration phase. Once the user-specific Stevens exponent is determined and stored, subsequent haptic output signals can be processed with simple multiplication operations, significantly reducing real-time processing complexity while maintaining user-specific adaptation.
Data Source
AI summary
Simulated textures whose parameters are held with object model data in a data store are modified in accordance with data held in data store which data defines a Gamma correction factor previously determined for each identified user. The gamma correction factor is determined by outputting to a Haptic Output interface a texture simulation including spaced grooves or ridges. By correlating user response to the perceived “feel” of the texture (rough, medium or smooth scale for example) the user's perceptual factors can be determined. Subsequently applying the perceptual factors to effect a mathematical adjustment (power) of texture in simulation algorithms allows output simulations to be adapted so that each user has a corresponding perception of the simulated objects.