Date of Award

6-2018

Document Type

Open Access

Degree Name

Bachelor of Science

Department

Mechanical Engineering

First Advisor

Professor William Keat

Second Advisor

Professor John Rieffel

Language

English

Keywords

Tensegrity, Resonance, Generic Algorithms, Strut, Robot

Abstract

A tensegrity is a structure composed of a series of rigid members connected in static equilibrium by tensile elements. A vibrating tensegrity robot is an underactuated system in which a set of its struts are vibrated at certain frequency combinations to achieve various locomotive gaits. Evolutionary robotics research lead by Professor John Rieffel focuses on exploiting the complex dynamics of tensegrity structures to control locomotion in vibrating tensegrity robots by finding desired gaits using genetic algorithms. A current hypothesis of interest is that the optimal locomotive gaits of a vibrating tensegrity exist at its resonant frequencies.

In order to observe this potential phenomenon, a fully instrumented tensegrity strut module capable of actuating the resonant modes of a vibrating tensegrity and observing the dynamics of its individual struts was developed. The strut consists of a laser-cut acrylic base, a custom DC vibration motor, a 6-axis IMU with onboard data collection, and Bluetooth connectivity for wireless control. Single strut vibration was theoretically modeled and validated against the experimentally observed dynamics. The final iteration of this design successfully actuated the resonant modes of the tensegrity and achieved sufficient motion capture capabilities with a sampling rate of 425 Hz. Additionally, experimental testing with the strut revealed a new frequency-locking phenomenon present in the frequency response of the strut’s vibration.

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