Musculoskeletal (MSK) systems have long been compared to simple mechanical machines. This not only allows for ease of understanding locomotion, but ease of modeling a biological system during complex motion. More specifically, simple lever systems are most commonly employed to approximate mechanical performance of complex biological systems. Every simple lever system can be characterized by its mechanical advantage, also known as gearing. Through this concept, the performance of a biological system can be modeled for comparability of theoretical concepts to actual MSK systems. In this thesis, a numerical model of a simple lever system, analogous to a locust leg and fish fin, was developed to understand the effects of mechanical advantage, muscle actuator, and external forces on simple MSK systems. Validation of the numerical model was attempted through the use of an existing McKibben air muscle test fixture. Conditions related to force loading, inertial loading, and viscous loading were tested.

The mathematical model showed that the spring-damper in parallel matches the expected results of the Hill’s muscle model, where increases in muscle loading cause decreases in muscle velocity. Further, experimental tests conducted on the existing test fixture employed the addition of two dampers parallel with the McKibben air muscle. The data suggested that for a given damping scenario, under direct loading conditions, there is a maximum potential contractile velocity that could be achieved. Inertial loading tests provided a comparison in the fluid effects where observations illustrate the 100% glycerine trials caused a greater drag force to dampen the paddle velocity than the room temperature water solution.

Library of Congress Subject Headings

Musculoskeletal system--Mathematical models

Publication Date


Document Type


Student Type


Degree Name

Mechanical Engineering (MS)

Department, Program, or Center

Mechanical Engineering (KGCOE)


Steven Day

Advisor/Committee Member

Kathleen Lamkin-Kennard

Advisor/Committee Member

Mario Gomes


Physical copy available from RIT's Wallace Library at QP303 .H67 2016


RIT – Main Campus

Plan Codes