Clam Shell Mask for Accurate Pupil Tracking
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Solution Overview
Problem
Current eye tracking technologies for cognitive assessment face challenges such as environmental distractions, head position errors, and high costs, which affect the accuracy of gaze angle measurements, and are not optimized for cognitive analysis, requiring precise camera placement and complex calibration processes.
Innovation Solution
A portable desktop system with a mask that positions the face normal to the screen, using low-cost cameras and red LED illumination to track pupil position accurately, eliminating the need for complex calibration and reducing environmental noise, and incorporating handholds to stabilize the head, thereby enhancing gaze direction measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a computer screen is used to present the test dot, then the system becomes portable and cost-effective, but environmental effects such as ambient light and distractions disturb the test subject
Solution Approach 1:
The system is divided into separate functional components: a portable computer for dot presentation, a dedicated mask for environmental control, and separate camera systems for eye tracking. This segmentation allows each component to be optimized independently, with the mask specifically addressing environmental interference while the computer maintains portability.
Solution Approach 2:
The mask acts as an intermediary between the test subject and the environment, creating a controlled optical environment without requiring a fully enclosed chamber. It blocks ambient light and distractions from reaching the test subject's field of view while allowing the necessary test stimuli to be presented.
2Device complexity
If standard camera placement is used, then the system is simple to implement, but head position errors introduce large errors in gaze angle measurement
Solution Approach 1:
The mask pre-positions the test subject's head in the correct orientation and location before the eye tracking measurement begins. By establishing the proper head-camera-relative geometry in advance through the mask's physical structure, the system eliminates the need for complex real-time head position compensation algorithms.
Solution Approach 2:
The solution moves from trying to measure and compensate for head position in 3D space to using a 2D mask structure that physically constrains the head to the correct position. This dimensional approach converts a complex spatial measurement problem into a simpler physical constraint problem.
3Ease of manufacture
If corneal reflection techniques are used for gaze tracking, then the system can work with standard cameras, but the measurement accuracy is reduced compared to pupil position recognition
Solution Approach 1:
The mask creates locally optimized lighting conditions around each eye by blocking ambient light while allowing controlled illumination. This local environmental control enhances the contrast and visibility of the pupil, enabling accurate pupil position detection with standard cameras without requiring specialized imaging equipment.
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 system provides accurate and cost-effective gaze direction measurements, reducing errors and environmental noise, and simplifying the user interface, while minimizing the need for high-cost hardware, thus improving cognitive impairment assessment.
Implementation Method 1
red LED illumination to track pupil position accurately
Implementation Method 2
track pupil position accurately
Data Source
AI summary
A highly portable desktop arrangement for cognitive testing which eliminates environmental effects is provided by a clam shell enclosure having a face mask on one face and housing a computer screen at an opposing wall, with accurate gaze direction measurement made by determining the position of the pupil if an individual whose face is pressed to the mask for eliminating head movement relative to the computer screen.