An actuating mechanism for evaluation of elbow joint motor function

• Main Author: Tiang, Peck Hor.
• Other Authors: Ling Shih Fu
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Mechanical engineering::Assistive technology; DRNTU::Engineering::Mechanical engineering::Bio-mechatronics
• Online Access: http://hdl.handle.net/10356/53964
• Institution: Nanyang Technological University

The motor function of human joints affects many activities in our lives. In particular, the human elbow joint is a critical joint which may experience impairment to its motor function due to medical conditions such as stroke and muscle dystrophy. Descriptive techniques were often used to measure the status of the limbs and joints, which were highly subjective and lack resolution. In this report, a novel method of employing the transduction matrix of an actuator would be introduced to measure the mechanical impedance of the arm. The transduction matrix is a 2 x transfer matrix relating the input ports and the output ports, such that if the input values are known, the corresponding output values can be calculated using the transduction matrix. Experiments were carried out on a motor driven actuating mechanism to obtain the system’s transduction matrix, and the measured impedance was within a 9% error margin, for a specified range of torque values. The transduction matrix of the system was validated using a linear extension spring to compare the theoretical and experimental mechanical impedance values. Despite the deviations from the theoretical impedance values, the experimental method was considered valid due to flaws in the assumption of the theoretical model and other issues. Eventually the highlight of the project was to measure the mechanical impedance of the human arm. A healthy upper limb was found to have mechanical impedance range that was numerically close to the reference impedance value of the actuating mechanism system. Several disorder conditions were also simulated to compare against the reference value. The results concluded that the transduction matrix could measure the mechanical impedance of the arm and distinguish between different elbow motor functions and classify the upper limb based on 3 scenarios. However, the results were inconclusive as the experiment had insufficient sampling population and the results were based on simulated scenarios. Nonetheless, this method provided an accurate, relatively cheap and objective method as compared to existing methodologies. A design of a multi-motion path actuating mechanism for future work was also included in the appendix.