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Material Type: Notes; Professor: Fregly; Class: BIODYNAMICS; Subject: ENGINEERING SCIENCE; University: University of Florida; Term: Unknown 1989;
Typology: Study notes
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While working for a biodynamics company, you are given the opportunity to demonstrate your knowledge of Autolev, Matlab, motion analysis, human anatomy, intermediate reference frames, and three-dimensional (3D) rotations. An orthopedic surgeon with whom you work wants to know a patient’s left hip flexion-extension, internal-external rotation, and abduction-adduction during gait movement recorded with a marker-based motion analysis system. A schematic of the left hip region is shown below along with the motion capture marker locations and recommended body segment coordinate systems.
For this assignment, your goal is to create the pelvis and thigh segment coordinate systems, define a 3D rotation matrix between the pelvis and thigh, and use inverse trigonometric calculations to compute two distinct sets of three Euler angles from the rotation matrix. Before proceeding to the following pages you will need to download and save the 3D rotations homework files from the course web page.
To complete the assignment, you need to perform the series of steps indicated below.
Body 3 1-2-3 Rotation Matrix
R (^) Body 31 − 2 − 3 =
Body 3 3-1-2 Rotation Matrix
R (^) Body 33 − 1 − 2 =
Matlab and Data Files
Place the Matlab file (Rotations_3D.m) and the six input data files (r_asis.txt, l_asis.txt, sacral.txt, thigh_upper.txt, thigh_front.txt, and thigh_rear.txt) in your Matlab working directory.
Pelvis Segment Coordinate System
In the appropriate section of Rotations_3D.m, define the pelvis segment coordinate system for the current time frame (f).
Generating Results
Discussion
Considering your goal of quantifying a patient’s hip joint movement, which rotation sequence (i.e., 1-2-3 or 3-1-2) would you choose? Why?