Bill Day's pictureBill Day

Hope College

Dr. Thelen , Dr. Luchies

Supported by NIH

y summer research consisted of modeling and simulating the lower extremity musculoskeletal system. Working Model(tm) and Matlab(tm) software packages were used in this work. This research gave me the opportunity to apply modeling and simulation skills learned in my mechanical engineering curriculum.

The objective of our research is to determine the effects of age on muscle function and balance recovery. Our work utilized data from an experiment performed during the summer of 1995. In that experiment, kinematic, myoelectric and force data were recorded from young and elderly subjects as they took rapid steps to regain balance following release from a forward lean.

I developed and used two different models to simulate and understand the data collected during that experiment. The first, an inverse dynamics model, inputs body segment positions and external force data, and calculates the resultant torques at the ankle, knee and hip joints. These calculated torques are the resultant of the torques created by each muscle.

The second model is referred to as the direct dynamics model. This model is much more complicated. It consists not just of the bodies, and joints, but all the major muscle groups in the legs and hip. The muscles are represented as non-linear actuators in Working model. Filtered EMG signals collected from subjects are then sent to these actuators, which produce force. Body segment positions are predicted by the model. This model is to being used to determine which parameters (strength, tendon stiffness, muscle speed) change with age and contribute to balance difficulties in elderly adults.

dayw@hope.edu