When designing a medical device based on lightweight accelerometers, the designer is faced with a number of questions in order to maximize performance while minimizing cost and complexity: Where should the inertial unit be located? How many units are required? How is performance affected if the unit is not correctly located during donning? One way to answer these questions is to use position data from a single trial, captured with a nonportable measurement system (e.g., stereophotogrammetry) to simulate measurements from multiple accelerometers at different locations on the body. In this paper, we undertake a thorough investigation into the applicability of these simulated acceleration signals via a series of interdependent experiments of increasing generality. We measured the dynamics of a reference coordinate frame using stereophotogrammetry over a number of trials. These dynamics were then used to simulate several “virtual” accelerometers at different points on the body segment. We then compared the simulated signals with those directly measured to evaluate the error under a number of conditions. Finally, we demonstrated an example of how simulated signals can be employed in a system design application. In the best case, we may expect an error of 0.028m/s2 between a derived virtual signal and that directly measured by an accelerometer. In practice, however, using centripetal and tangential acceleration terms (that are poorly estimated) results in an error that is an order of magnitude greater than the baseline. Furthermore, nonrigidity of the limb can increase error dramatically, although the effects can be reduced considerably via careful modeling. We conclude that using simulated signals has definite benefits when an appropriate model of the body segment is applied.

1.
Giansanti
,
D.
,
Maccioni
,
G.
, and
Macellari
,
V.
, 2005, “
The Development and Test of a Device for the Reconstruction of 3-D Position and Orientation by Means of a Kinematic Sensor Assembly With Rate Gyroscopes and Accelerometers
,”
IEEE Trans. Biomed. Eng.
0018-9294,
52
(
7
), pp.
1271
1277
.
2.
Mansfield
,
A.
, and
Lyons
,
G. M.
, 2003, “
The Use of Accelerometry to Detect Heel Contact Events for User as a Sensor in FES Assisted Walking
,”
Med. Eng. Phys.
1350-4533,
25
(
10
), pp.
879
885
.
3.
Karantonis
,
D. M.
,
Narayanan
,
M. R.
,
Mathie
,
M.
,
Lovell
,
N. H.
, and
Celler
,
B. G.
, 2006, “
Implementation of a Real-Time Human Movement Classifier Using a Triaxial Accelerometer for Ambulatory Monitoring
,”
IEEE Trans. Inf. Technol. Biomed.
1089-7771,
10
(
1
), pp.
156
167
.
4.
Lindemann
,
U.
,
Hock
,
A.
,
Stuber
,
M.
,
Keck
,
W.
, and
Becker
,
C.
, 2005, “
Evaluation of a Fall Detector Based on Accelerometers: A Pilot Study
,”
Med. Biol. Eng. Comput.
0140-0118,
43
(
5
), pp.
548
551
.
5.
Heller
,
B. W.
, 1992, “
The Production and Control of Functional Electrical Stimulation Swing-Through Gait
,” Ph.D. thesis, Strathclyde University, UK.
6.
Tong
,
K. Y.
, and
Granat
,
M. H.
, 1998, “
Virtual Artificial Sensor Technique for Functional Electrical Stimulation
,”
Med. Eng. Phys.
1350-4533,
20
(
6
), pp.
458
468
.
7.
Cappozzo
,
A.
,
Catani
,
F.
,
Della Croce
,
U.
, and
Leardini
,
A.
, 1995, “
Position and Orientation in Space of Bones During Movement: Anatomical Frame Definition and Determination
,”
Clin. Biomech.
,
10
(
4
), pp.
171
178
. 1350-4533
8.
Craig
,
J. J.
, 1989,
Introduction to Robotics: Mechanics and Control
,
2nd ed.
,
Addison-Wesley
,
Reading, MA
.
9.
Baruh
,
H.
,
Analytical Dynamics
,
McGraw-Hill International Editions
,
New York
.
10.
Tresadern
,
P.
,
Thies
,
S. B.
,
Kenney
,
L. P. J.
,
Howard
,
D.
, and
Goulermas
,
J. Y.
, 2007, “
A Clinical Set-Up Tool (CST) for Rapid Stimulator Programming
,”
Proceedings of the International Conference of the IEEE Engineering in Medicine and Biology Society
, Aug., pp.
3577
3580
.
11.
Thies
,
S. B.
,
Tresadern
,
P.
,
Kenney
,
L.
,
Howard
,
D.
,
Goulermas
,
J. Y.
,
Smith
,
C.
, and
Rigby
,
J.
, 2007, “
Comparison of Linear Accelerations From Three Measurement Systems During “Reach & Grasp”
,”
Med. Eng. Phys.
1350-4533,
29
(
9
), pp.
967
972
.
12.
Sobuh
,
M.
,
Kenney
,
L. P. J.
,
Tresadern
,
P.
,
Twiste
,
M.
, and
Thies
,
S.
, 2008, “
Accelerometry-Based Activity Monitoring for Upper Limb Prosthesis Evaluation
,”
Proceedings of the International Conference on Ambulatory Monitoring of Physical Activity and Movement
.
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