An Energy Harvesting Device for Powering Rotor Load Monitoring Sensors

Open Access
Santarelli, David
Graduate Program:
Mechanical Engineering
Master of Science
Document Type:
Master Thesis
Date of Defense:
April 23, 2010
Committee Members:
  • Christopher Rahn, Thesis Advisor
  • Edward Smith, Thesis Advisor
  • Stephen Clarke Conlon, Thesis Advisor
  • Energy Harvesting
  • Rotorcraft
  • Loads Monitoring
Health and Usage Monitoring Systems (HUMS) on helicopters help to determine when dynamic, flight critical components are replaced. These systems work on the principle of condition based maintenance and attempt to determine the usage of each component through regime recognition. The next step to improving HUMS is to directly monitor the components with on-board sensors that wirelessly communicate with the HUMS. This method would improve accuracy over regime recognition and help reduce maintenance costs and increase safety. Low power electronics, along with the desire to avoid battery replacement, make an energy harvesting solution an attractive option to power any wireless network sensor. This thesis presents the design of an electromagnetic energy harvester based on Faraday’s Law of Magnetic Induction. The design space for the harvester is the hollow rod end of a pitch link on a UH-60 Blackhawk helicopter. All of the relevant design equations relating to electromagnetic energy harvesting are presented and each variable is looked at individually. Three designs for an electromagnetic energy harvester that utilize the rigid motion of the pitch link are analyzed. For each design, an analytical model was made to determine the feasibility of implementing the design. One prototype was fabricated and tested to determine system parameters such as mass, stiffness, damping, and performance parameters such as voltage generated and power delivered to a load. There is relevant circuit design presented that would be necessary to implement in the final system. The final device is a pendulum system that uses a torsion spring and centrifugal force to realize an effective spring and tune the device to generate power. This design was shown to produce a maximum of 2 mW of power to a resistive load of 1000 ohms at 19 Hz excitation and a base acceleration level of 20 m/s2.