Gravity-Based Arm Motion Measurement Device
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Solution Overview
Problem
Measuring angular differences in the range of motion of limbs to diagnose injuries or diseases is challenging due to variability in body shape, age, and fitness level, and conventional methods like goniometers are not straightforward for all users.
Innovation Solution
A device comprising a gripping bar with a midpoint housing and an angle-determining assembly that includes a weighted needle and compass, allowing patients to raise their arms to physiological limits while the compass indicates the angular difference, facilitating easy measurement and diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a goniometer is used to measure the angle of arm raise, then measurement capability is achieved, but proper placement, measurement, and reading becomes not straightforward for all persons
Solution Approach 1:
A plumb line is introduced as an intermediary reference element that hangs vertically from a fixed point. This plumb line serves as a universal reference that any user can observe and use to measure angular deviation, eliminating the complexity of proper goniometer placement and reading while maintaining measurement accuracy.
Solution Approach 2:
The complex mechanical goniometer system with multiple components requiring precise alignment is replaced with a simpler system using a hanging plumb line and visual angle estimation. This substitution maintains the essential measurement function while dramatically improving ease of operation for users of all skill levels.
2Measurement precision
If multiple measurements are taken to compare injured and healthy limbs, then diagnostic accuracy is improved, but uncertainty is unnecessarily inserted into diagnosis and treatment
Solution Approach 1:
The measurement of both injured and healthy limbs is merged into a single simultaneous measurement process. By having the patient hold both arms up and observe the angular difference directly against the plumb line reference, both measurements are taken together under identical conditions, eliminating variability between separate measurements and reducing uncertainty.
Solution Approach 2:
Both arms are measured under equipotential conditions - same starting position, same reference frame (plumb line), and same observation method. This creates equivalent measurement conditions for both injured and healthy limbs, allowing direct comparison without the uncertainty introduced by multiple separate measurements.
3Measurement precision
If conventional goniometer methods are used, then angle measurement is possible, but the method is not straightforward for all persons due to variability in body shape, age, and fitness level
Solution Approach 1:
The plumb line reference system is a universal measurement approach that works for all patients regardless of body shape, age, or fitness level. Unlike goniometers that require anatomical landmarks and proper positioning specific to each patient, the hanging plumb line provides a universal vertical reference that any patient can use to measure arm raise angle from any starting position.
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 measurement of angular differences in arm motion, aiding in the diagnosis of injuries or diseases such as arthritis, fractures, and neurological disorders, and providing a method for monitoring treatment progress.
Implementation Method 1
a weighted needle configured to point vertically when subjected to the force of gravity
Data Source
AI summary
A device for measuring an angular difference in a range of motion of the arms of a patient comprises a gripping bar, a housing, and an angle-determining assembly comprising a weighted needle and a compass. When the patient raises her arms to their unassisted physiological limits, the device indicates an angle that represents the angular difference in the range of motion between the arms of the patient.