Towards a Novel Mechanical Displacement Amplification Based Impulse Harvester for Prosthetics

Open Access
Author:
Chilson, Brian Daniel
Area of Honors:
Mechanical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Aman Haque, Thesis Supervisor
  • Jacqueline Antonia O'Connor, Honors Advisor
Keywords:
  • Mechanical
  • displacement amplification
  • MDA
  • energy harvesting
Abstract:
Mechanical displacement amplification technology has a plethora of applications from large-scale gear trains and levers to micromechanical piezo-actuators and even variable braille displays. These are devices that accept an input displacement and, through a combination of connective linkages, amplify said displacement with the corresponding minimization of force output consistent with energy conservation. Common applications for micromechanical displacement amplifiers (MDA) include energy generation from ambient kinetic sources such as vibration, wave motion, or wind. Piezo-materials, which respond to an induced voltage with small elongations, are commonly coupled with MDA technology to amplify the output displacement from the piezo-material and develop more viable piezo-actuators. This thesis proposes a novel small-scale compliant mechanical displacement amplification mechanism designed for high force-input ambient kinetic energy generation. The 15.72-gram mechanical displacement amplifier proposed herein exhibits an amplification ratio of 28.68 with a corresponding force transmission of 2.44% in response to an 800-Newton force input. It demonstrates a resonance frequency of 100.2 Hz. It is designed to be constructed from hot isostatically pressed titanium alloy Ti-6Al-4V due to this material’s high-strength, low-density, magnetic properties, and conductivity to flexure hinges. The mechanism is compliant and relies on flexural hinges rather than sliding joints in its connectivity; this enhances durability, reduces maintenance, and permits manufacturing via additive manufacturing. Finally, this thesis suggests coupling electromagnetic energy generation technology with the MDA for the construction of a high force input, low-displacement ambient kinetic energy generator.