Asee peer logo

Towards an Artificial Bullfrog: Development of a Kinematically Realistic, Articulated Skeletal Model

Download Paper |


2011 ASEE Annual Conference & Exposition


Vancouver, BC

Publication Date

June 26, 2011

Start Date

June 26, 2011

End Date

June 29, 2011



Conference Session

DEED Poster Session

Tagged Division

Design in Engineering Education

Page Count


Page Numbers

22.1536.1 - 22.1536.14



Permanent URL

Download Count


Request a correction

Paper Authors


Amy E. Cook Northern Arizona University

visit author page

Amy E. Cook is in her sophomore year as a mechanical engineering student at Northern Arizona University. Her research began with the acceptance of the NAU NASA Space Grant Internship in the year 2010. She is working under two mentors (Perry Wood and Theodore Uyeno) to guide her and offer any assistance needed for completing the attached research. The research is to be completed by April of 2011.

visit author page


Perry G. Wood Northern Arizona University

visit author page

Perry G Wood is currently an instructor at Northern Arizona University in the college of Mechanical Engineering, Flagstaff, Arizona. He has a bachelor's degree in Mechanical engineering from Northern Arizona University, and a master's degree in mechanical engineering from the Northern Arizona University. He is the faculty advisor for the student section of ASME. His experience includes various engineering positions at Raytheon, M.C. Gill Corporation, Royal Plastics Engineering, SouthWest Windpower, and the Naval Research Laboratory. He is a practicing professional mechanical engineer in the state of California, and Nebraska.

visit author page


Theodore A. Uyeno Northern Arizona University

visit author page

Dr. Uyeno is an Adjunct Professor of comparative biomechanics in the department of biological sciences at Northern Arizona University. His specialty is the analysis of invertebrate joint structures and biological material properties.

visit author page

Download Paper |


Towards an Artificial Bullfrog: Development of a Kinematically Realistic, Articulated Skeletal ModelThe purpose of this project was to create a high resolution, physical model of a realisticallyarticulated bullfrog skeleton. Such a skeletal model would be beneficial to biomechanicists whostudy locomotion and behavior, to surgeons for planning complex surgeries, and to roboticistswho desire a life-like robotic platform. Here we describe a unique process that resulted in arapid-prototyped, articulated skeleton that incorporated scanned bone geometry and actual jointkinematics.The workflow began with collecting anatomical and behavioral data. We imaged the bullfrogskeleton in three-dimensions using a GE lightspeed VCT scanner (512x512x302 slices, 350x350x625 μm resolution). Next, we manually defined the major bone groups and jointsresponsible for the largest motions and deformations apparent in the bullfrog feeding lunge. Thisresulted in a tessellated computer model that was segmented to contain twenty-five links andtwenty-six joints. We then used image digitizing software (Didge, A. Cullum, Creighton Univ.)to analyze individual frames of high-speed and X-ray video recordings of frog feeding lunges toassess the kinematic joint parameters. For each joint we measured the degrees of freedom andranges of motion.The next step in the workflow involved using SolidWorks (Dassault Systems, Concord MA) tomodify the bone groups by adding articulated joints with realistic kinematics. Because biologicaljoints employ complex, flexible soft tissue connections, they were inappropriate for modelingusing a rapid prototyping system. As such, we replaced the biological joints with moreconventional engineering joints that we designed to mimic the observed degrees of freedom andranges of motion. Finally, to print the skeleton, we scaled it up by a factor of three to meet theminimum resolution of the rapid prototyping machine (Dimension 1200es Series fuseddeposition 3D printer).This workflow resulted in a geometrically accurate physical model with joint kinematics thatresembles a real bullfrog skeleton. Ultimately, we would like to use this skeletal model as afoundation for testing biological hypotheses of form and function. As such, there are a number ofareas of which we would like to progress with this project. More realism could be achieved bysegmenting and modeling some of the less dynamic bones and joints. Also, with the addition ofartificial muscle, this kinematic skeleton could be used as a basis for realistic robots that allow usto test hypotheses of neural control.

Cook, A. E., & Wood, P. G., & Uyeno, T. A. (2011, June), Towards an Artificial Bullfrog: Development of a Kinematically Realistic, Articulated Skeletal Model Paper presented at 2011 ASEE Annual Conference & Exposition, Vancouver, BC. 10.18260/1-2--18462

ASEE holds the copyright on this document. It may be read by the public free of charge. Authors may archive their work on personal websites or in institutional repositories with the following citation: © 2011 American Society for Engineering Education. Other scholars may excerpt or quote from these materials with the same citation. When excerpting or quoting from Conference Proceedings, authors should, in addition to noting the ASEE copyright, list all the original authors and their institutions and name the host city of the conference. - Last updated April 1, 2015