Date of Thesis

Fall 2019



While rigid robots are extensively used in various applications, they are limited in the tasks they can perform and can be unsafe in close human-robot interactions. Soft robots on the other hand surpass the capabilities of rigid robots in several ways, such as compatibility with the work environments, degrees of freedom, manufacturing costs, and safe interactions with the environment. This thesis studies the behavior of Fiber-Reinforced Elastomeric Enclosures (FREEs) as a particular type of soft pneumatic actuator that can be used in soft manipulators. A dynamic lumped-parameter model is created to simulate the motion of a single FREE under various operating conditions and to inform the design of a controller. The proposed PID controller determines the response of the FREE to a defined step input or a trajectory following polynomial function, using rotation angle to control the orientation of the end-effector. Additionally, Finite Element Analysis method is employed, incorporating the inherently nonlinear material properties of FREEs, to precisely evaluate various parameters and configurations of FREEs. This tool is also used to determine the workspace of multiple FREEs in a module, which is essentially a building block of a soft robotic arm.

Both of these models provided a great understanding of a FREE's behavior in various working conditions. This understanding led to employing a group of FREEs in a module to explore new applications, Although, the finite element model was not able to fully and accurately predict the system response in all cases. It did however provide a basis of understanding for the trends in FREEs’ behavior in single and module configurations, and demonstrated the necessity of improving the fabrication process of FREEs. Results of the two models point to the importance of the manufacturing process in minimizing variations in FREE behavior. Overall, the developed models in this project efficiently predict the behavior of FREEs and they can potentially be used for future studies of FREEs and similar soft actuators.


robotics, soft robotics, robot manipulation, dynamics & control, modeling, finite element analysis

Access Type

Masters Thesis

Degree Type

Master of Science


Mechanical Engineering

First Advisor

Keith W. Buffinton