Document Type


Date of Award

Spring 5-31-1998

Degree Name

Master of Science in Biomedical Engineering - (M.S.)


Biomedical Engineering Committee

First Advisor

H. Michael Lacker

Second Advisor

David S. Kristol

Third Advisor

Peter Engler


In designing a device for an amputee, it is important to find those underlying principles which determine the normal human sit-to-stand task. For this purpose we have developed a mathematical model of human sit-to-stand movement, which it is possible to predict the minimum mechanical energy consumption to move from the sit-to-stand position.

To the best of author's knowledge, this thesis represents the first time that the periodic motion of stand-to-sit and sit-to-stand movements have been mathematically modeled by a simple mechanical system. A complex model, such as the one used by Seireg and Arvikar (1973) [1] that contained 31 muscles per leg, is certainly impressive from a mathematical point of view alone. However, biomechanists should always reduce as much as possible the complexity in their models. The discussions of what the appropriate level of complexity to model, this biomechanical process will probably never end.

Our purpose, for this thesis, is to develop a simple mathematical model of sit-to-stand motion, which can be used to understand the effects of parameter hanges, and to predict the human motion that minimizes energy expenditure. This knowledge can be used to design a mechanical device for this purpose. There are very few papers which explain mechanical and muscular dynamics of rising from a seated position, but unfortunately, no one has successfully constructed a model to solve the motion by forward dynamics.



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.