Date of Award

Spring 1-1-2016

Document Type


Degree Name

Master of Science (MS)


Mechanical Engineering

First Advisor

Mark Rentschler

Second Advisor

Lucy Pao

Third Advisor

Sean Humbert


In a continued effort to develop an active robotic colonoscope, research is being conducted on the development of the next generation of colonoscopic devices. Several locomotion principles such as legs, treads, magnets or worm-like motions are being investigated to allow for active control of the robot inside the large bowel. A worm-like motion, or peristaltic motion, has proven to be very effective in nature. This motion is used by worms to move in small cavities or by the small and large bowel to transport waste through the gastrointestinal tract. To generate a peristaltic wave in a robot, small and powerful actuators are needed. Shape memory alloy (SMA) springs are able to provide high amounts of power in very reduced sizes, making them very suitable for this application.

In this work, a soft SMA-actuated biomimetic robot using a peristaltic motion to translate is designed, modeled and controlled. An optimized silicon rubber skin is modeled and designed to improve the peristaltic motion while acting as the restoring force for the SMA springs. A complete characterization of the SMA springs actuators based on Tanaka`s model is experimentally obtained resulting in a modified constitutive model. Additionally, an approximated inverse kinematic and dynamic model are hypothesized for the soft robot and used in the controller design. A non linear single input single output controller is developed based on fuzzy control which then is used for the multi-input multi-output controller. The robot is entirely built and the controller implemented and tested. The robot demonstrates its ability to perform a peristaltic motion and orient to any pitch and roll configuration between -90 degrees and 90 degrees.

Available for download on Friday, July 31, 2020