Circumference Measurement Device with Constant Tension Spring
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Solution Overview
Problem
Current methods for determining the circumference of body parts for orthoses and prostheses are inconsistent due to varying tensile forces applied by different technicians, leading to uneven fitting and lack of reproducibility.
Innovation Solution
A device with a base body and a tension element that uses a gas pressure or oil pressure spring to exert a uniform tensile force on a band, allowing for consistent and reproducible circumference measurements, independent of the technician and measurement conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a tape measure is used with self-selected pulling force by the technician, then the measurement process is simple and quick, but the measurement precision and reproducibility deteriorate due to varying tensile forces
Solution Approach 1:
The spring element is pre-loaded to generate a predetermined tensile force before the measurement is taken. This preliminary action ensures that the correct measurement force is applied automatically, eliminating the need for the technician to judge the appropriate pulling force during the measurement process.
Solution Approach 2:
The measuring device serves itself by using the spring element to automatically apply the required tensile force to the band. The spring's predetermined force generation capability allows the device to self-regulate the measurement conditions without requiring skill or judgment from the operator.
2Ease of operation
If different technicians apply varying tensile forces, then the measurement process remains flexible and easy to operate, but the reliability and comparability of measurements deteriorate
Solution Approach 1:
The spring element is designed with specific mechanical properties (spring constant, pre-load) that define a predetermined tensile force parameter. By changing the spring's physical characteristics rather than relying on operator technique, the measurement conditions are standardized and reproducible across different technicians.
Solution Approach 2:
The spring element acts as an intermediary between the technician and the band. Instead of the technician directly applying force to the band (which varies with skill and strength), the spring mediates the force application, translating the technician's simple action of closing the device into a precise, predetermined tensile force on the band.
3Device complexity
If manual force application is used, then the device complexity is low, but the manufacturing precision of measurements deteriorates due to lack of force control
Solution Approach 1:
The complex task of force control is extracted from the measurement process and embodied in the spring element's predetermined mechanical properties. Rather than incorporating complex active control systems, the force control function is taken out and embedded in the passive mechanical design of the spring, maintaining device simplicity while achieving precision.
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 simple and quick determination of comparable and reproducible circumference values, ensuring optimal fit and function of orthoses and prostheses by maintaining a constant tensile force along the measurement process.
Implementation Method 1
The device further has a tension generating device which is set up to exert a uniform tensile force on the belt parallel to the first direction via the tension element, which is essentially independent of the displacement of the tension element. The device according to the invention is characterized in that the tension generating device has a gas pressure or an oil pressure spring.
Implementation Method 2
The device further has a tension generating device which is set up to exert a uniform tensile force on the belt parallel to the first direction via the tension element, which is essentially independent of the displacement of the tension element. The device according to the invention is characterized in that the tension generating device has a gas pressure or an oil pressure spring.
Data Source
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AI summary
The present invention relates to a device for determining the circumference of a body part comprising a base body, a tension element displaceable relative to the base body in a first direction, a band whose first end is fixedly connected to the base body at a reference point and whose second end can be locked to the tension element at a locking point of the tension element, and a measuring device for directly or indirectly determining the length of the band between the reference point and a measuring point and thereby the circumference of a body part encompassed by the band.