Transcript Microsoft PowerPoint 2007

MIMICKING COMPLEX SHOULDER MOTION USING A MULTI-DOF
ACTUATOR TO INVESTIGATE ROTATOR CUFF TEARS
BEN SLOTARSKI, BLASE HORN, HAFIZUR RAHMAN, MARIANA E. KERSH
Department of Mechanical Science and Engineering, College of Engineering, University of Illinois at Urbana-Champaign
METHODS
OBJECTIVE
TISSUE
BIOMECHANICS
LABORATORY
Z
The aim of this study is to have a
better understanding of the effect
of rotator cuff injury on cartilage
mechanics during daily activities
1
Y
2
Specific Aims:
 Mount physiological tissue to a
CNC machine
 Use the CNC machine to
replicate the kinematics of the
shoulder joint
3
θ
4
C
INTRODUCTION
 It is desired to get repeatable
motion for cyclic loading of
biological tissue
 The challenge was how to
mount biological tissue on
actuator machine
 The initial focus was shoulder
abduction on a saw bone
model
1 - CNC Mating Plate
2 - Load Cell
3 - Load Cell Adapter
4 - Scapula Mount
5 - Humerus Mount
6 - CNC Stage Adapter
5
PROCEDURE
 Move the saw bone by hand to get desired abduction motion,
and record the data using Optotrak software
 Convert data points to lines of G-Code for the CNC to read
6
A
B
Figure 1: A) Fixture 3D CAD Models, B) Actual CNC Model, C) CNC in Motion
 Record the CNC motion using the Optotrak, and compare
the results
RESULTS
DISCUSSIONS
 3D-printable, modular CAD template
 Machined aluminum for permanent
interfaces
 Error for angular translation was
higher compared to y-translation
 Impulsive motions are smoothed out
by CNC machine
 CNC gives kinematic overshoot and
undershoot at relative extrema
 Only five degrees of freedom possible
with CNC machine
FUTURE STUDY
 Apply the CNC actuation to animal
tissue
 Capture different shoulder motions
such as flexion and internal/external
rotations
 Replicate motion for other joints such
as the knee and wrist
Figure 2: Comparing Manual to CNC Angular Displacement
Figure 3: Comparing Manual to CNC Y-Displacement
ACKNOWLEDGEMENTS
 The CNC replicated manual manipulation of the saw bone within 2.31 mean
percent difference & 1.71 standard deviation for angular displacement
 The y-displacement had 1.03 mean percent difference & standard deviation 0.73
Professor Placid Ferreira
MechSE Machine Shop
James Nie