Graduate Studies, UNL
Embargoed Master's Theses
First Advisor
Carl Nelson
Committee Members
Brittany Duncan, Shane Farritor, Santosh Pitla
Date of this Version
12-2025
Document Type
Thesis
Citation
A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science
Major: Mechanical Engineering and Applied Mechanics
Under the supervision of Professor Carl Nelson
Lincoln, Nebraska, December 2025
Abstract
As modern manufacturing pursues upgraded processes and becomes more data driven, installations of Industrial Robots continue to surge. However, while these robots excel in repetitive tasks and roles carrying higher loads, they expose themselves to higher energy consumption and increased wear, so robots with five year expected lifespans may only survive in service as little as six months. To combat these issues, researchers have sought methods to reduce wear and energy consumption by optimizing trajectories; however, instances of discontinuous jerk (where robot accelerations and decelerations approach excessive values) continue to disturb robot trajectories and efficiencies. For these reasons and their wide applicability to other problems, Variable Stiffness Mechanisms, devices capable of tuning their stiffness via mechanical principles, are growing in popularity as hardware-oriented solutions. Efforts implementing these mechanisms have showcased their potential to bound robot jerk and thus reduce wear and energy consumption in Industrial Robots. While designs continue to improve, many concepts contain intricate or cumbersome features; furthermore, most are strictly designed for integration in rotational joints, limiting their use and slowing their ability to break into the market. Inspired by these reasons, this thesis outlines work to develop a prototype of a novel Cartesian Variable Stiffness Mechanism (CVSM) with complaint features, designed to mount between the robot’s end of arm tooling and its payload. Furthermore, it details development of the CVSM conceptual design, component fabrication, assembly, and finally testing. Experimental evaluations describe its ability to effectively change its stiffness and aid in pick-and-place applications typical of industrial use cases. Lastly, concluding remarks on the CVSM’s design and efforts for future work are outlined.
Advisor: Carl Nelson
Advisor: Dr. Carl Nelson
Comments
Copyright 2025, Benjamin L. Zwiener. Used by permission