Author: Dinithi Rasaara Hemakumara
Hemakumara, Dinithi Rasaara, 2024 Development of a Low-cost, Accurate System for Measuring Low Back Movements During Daily Activities, Flinders University, College of Science and Engineering
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Lower back pain is the leading cause of disability, worldwide. Poor posture, sedentary lifestyle, and incorrect body mechanics during daily activities cause lower back pain. Monitoring the movements of the lower back during daily activities helps prevent the occurrence of injury and avoid lower back pain. This project was initiated to develop a portable, non-invasive system capable of reproducing the outcomes of radiography techniques when monitoring lower back movements for prolonged periods of time. A potentiometer-based sensor system was developed to meet the project goals. A validation study was done on the selected sensor to evaluate its performance. The enclosure of the system was designed based on the universal joint design to allow 3 rotational Degrees of Freedom (DOF). The design was iteratively modified, 3D printed with Polylactic Acid (PLA) and tested to derive the most optimized enclosure design. The results obtained indicate that the selected sensor is linear throughout its operational range with a linearity error less than 2%, has a low hysteresis of 0.02 mV proving that the sensor can produce accurate, precise, and stable outputs. Based on its linearity, an equation was derived to measure the angle (°) for a known voltage output (mV). Upon assembly and integration of sensors and enclosure design, the functionality of the developed system was validated with the aid of a simple mechanical system built with the aid of a stepper motor, where sensor readings were obtained by rotating the motor shaft to predefined values. The results from validation testing showed that the developed sensor system can produce results for flexion/extension, and lateral bending with an error within 1° for an approximate range of −10° to +10° of orientation. For rotation/twisting the error was approximately 2° for this range. This range of measurement for flexion/extension and lateral bending is sufficient to measure intervertebral movements of the lumbar vertebrae. Therefore, by utilizing the recommendations in future work section of the thesis, the developed system has great potential to replace radiography methods for measuring lower back movements.
Keywords: Lower back, Non-invasive, Prolonged measurements, Sensors, Accuracy
Subject: Medical Biotechnology thesis
Thesis type: Masters
Completed: 2024
School: College of Science and Engineering
Supervisor: Associate Professor John Costi