Self-Locating Sensor Mounting Apparatus for Head-Mounted Devices
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Solution Overview
Problem
Existing methods for positioning sensors on the head, such as EEG electrodes, face challenges due to varying head sizes and shapes, leading to uneven expansion and tilting issues with elasticized structures, requiring skilled personnel for accurate placement.
Innovation Solution
A self-locating mounting apparatus with inextensible elements and sliding expansion joints, combined with biasing elements like elastic cords or springs, allows for automatic fitting to different head sizes while maintaining sensor position accuracy and preventing rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an entirely elasticized structure is used to accommodate varying head sizes, then the mounting apparatus can expand to fit different heads, but the sensors become tilted and positioned unevenly due to uneven expansion
Solution Approach 1:
The mounting apparatus is divided into inextensible elements (rigid segments) connected by sliding expansion joints, allowing the structure to expand in a controlled manner while maintaining the relative positions of sensor mounting points. This segmentation enables the apparatus to adapt to different head sizes without compromising sensor positioning accuracy.
Solution Approach 2:
The apparatus incorporates sliding expansion joints that allow dynamic adjustment of the structure's dimensions. These joints enable the mounting apparatus to expand and contract smoothly, accommodating varying head circumferences while keeping the sensor positions fixed relative to the head surface.
2Force
If sensors are attached to the mounting apparatus at a distance from the scalp, then the force can be applied normal to the head, but the moment increases causing rotation of the objects
Solution Approach 1:
The mounting units are designed with a multi-dimensional structure that includes both a mounting surface for the sensor and a contact surface for the head. By orienting the sensor mounting surface at an angle or offset from the contact surface, the design creates a mechanical advantage where the biasing force applied normal to the head is translated into both pressing force on the sensor and counteracting moment to prevent rotation.
3Manufacturing precision
If careful measurements by trained personnel are used to position sensors, then accurate placement according to the 10/20 scheme is achieved, but the process becomes complex and time-consuming
Solution Approach 1:
The mounting apparatus is designed to self-locate and automatically position the sensors according to the 10/20 scheme without requiring external measurement or adjustment by trained personnel. The inextensible elements with fixed geometric relationships and the sliding expansion joints work together to automatically accommodate head size variations while maintaining accurate sensor positions, eliminating the need for manual measurement and placement procedures.
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
Enables accurate and reproducible placement of sensors by unskilled personnel, accommodating various head sizes without tilting, and allows for extended wear with minimal discomfort, suitable for medical and military applications.
Implementation Method 1
an inextensible circumferential band connected by sliding expanding joints to the central mount via inextensible side elements
Implementation Method 2
biasing elements in the form of elastic cords or springs are utilized to bias the mounting units towards the subject
Implementation Method 3
biasing elements in the form of elastic cords or springs are utilized to bias the mounting units towards the subject
Data Source
AI summary
A self-locating mounting apparatus for holding objects such as sensors at specific positions on a subject's head includes a central mount constituted by a plurality of inextensible elements adapted to fit over the top of a subject's head. In addition, the mounting apparatus includes an adjustable circumferential band adapted to circle the subject's head and connect the central mount to inextensible side elements via sliding joints. A plurality of biasing elements provide a force for biasing sensor mounting units on the mounting apparatus against a subject's head, allowing for long-term sensing while minimizing interference forces on the mounting units. Advantageously, the mounting apparatus holds sensors within approximately 5 mm of their desired measurement positions over a range of subject head sizes.