evaluation of human walking
TRANSCRIPT
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An Experimental Evaluation of Human Walking
ERIKA OTTAVIANO,MARCO CECCARELLI,SALVATORE GRANDE
LARM: Laboratory of Robotics and Mechatronics, DiMSAT, University of Cassino
Via Di Biasio 43 - 03043 Cassino (FR), Italy e-mail: ottaviano/[email protected]
Abstract In this paper an application of a cable-based measuring system is presented for an
experimental evaluation of human walking characteristics. Experimental results have been
obtained by means of a new version of CATRASYS (Cassino Tracking System), which is a
measuring system that has been designed and built at LARM: Laboratory of Robotics and
Mechatronics in Cassino. The new version of the CATRASYS system has been completed with
force sensors so that it can monitor pose (position and orientation) and force that are related to a
properly designed human-machine interface end-effector. This capability has been used to
determine kinematic characteristics of human users during walking operations and furthermore to
measure forces/torques that are exerted by a limb during the motion. Several experimental tests
have been carried out to explore the influence of: gender, age, height, weight. The influence of
carrying a load is investigated together with the influence of different types of shoes. In the paper,
results are shown and discussed as suitable for medical applications, both for diagnosis procedures
and rehabilitation therapies of human limbs.
Keywords: Experimental Robotics, Parallel Manipulators, Cable-Based Architectures, Measuring
Systems, Biomechanics.
1 Introduction
The biomechanics of human movement has been
extensively studied from experimental point of
view and further simulation.
In the field of clinical gait analysis, medical
professionals apply an evolving knowledge basedon the interpretation of the walking patterns of
impaired people for planning of treatment
protocols, e.g. and surgical prescription and
intervention and allow the clinician to determine the
extent o which an individuals gait pattern has been
affected by an already diagnosed disorder [1].
Several measuring systems can be used for the gait
analysis, commercial optical systems such as Vicon
(reflective markers) or Optotrak (active markers)
are often considered in human motion analysis
[2,3]. Although these systems provide accurate
position information (declared accuracy 1mm),
there are some important limitations. The mostimportant factors are the high costs and limited
measurement volume. The use of a specialized
laboratory with fixed equipment limits the range of
possible applications, like monitoring of daily life
activities, control of prosthetics or assessment of
workload in ergonomic studies.
In the past few years, the health care system trend
toward early discharge to monitor and train patients
in their own environment. This has promoted a
large development of non-invasive portable and/or
wearable systems [4,5].
In this paper we proposed a cable-based measuring
system, which appear to be interesting as pose
measuring device since it presents favourable
features, such as portability, low-cost, relatively
good accuracy and large measuring volume [6, 7].
In particular, the attached problem consists in
developing a system with monitoring features of
main walking characteristics whose feasibility has
been proved through laboratory tests.
Main properties of the proposed system can be
recognized as an extension of the original
CATRASYS design in terms of low-cost design
and easy-operation implementation.
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The reported experiences have not full medical
insights, but they show interesting results, which
can be considered promising also for a true medical
application.
2 The human walking
All gaits that have no flight phase, in which there is
not an interval of time when neither leg touches the
ground, are often classified as walking. Clearly, by
this definition, there are infinitely many such
walking gaits.
The human gait can be divided into gait cycles,
which are defined as the period from an initial
contact of one foot to the following initial contacton the same foot. This period can be divided into
three main tasks, which can be further divided into
eight phases [8].
The first task is a weight acceptance period, which
involves an initial contact phase and a loadingresponse phase. During this task, one foot is placedon the ground and the body weight is shifted to
maintain stability and absorbing shock.
The second task is a single limb support task
consisting of a mid-stance phase, a terminal stance
phase and a transition to the pre-swing phase.
During this task, the contra-lateral foot is swungforward while the body weight is maintained on the
stable foot.
The last task is the limb advancement, which
consists of the pres-wing phase, the initial swing
phase, the mid-swing phase and the terminal swing
phase. During this task, the previously stable footleaves the ground, shifting the body forward.
Generally, motion analysis data collection
protocols, measurement precision, and data
reduction models have been developed to meet the
requirements for their specific settings.
Many systems can be used for measuring body
segment positions and angles between segments.
They can be categorized in mechanical, optical,
magnetic, acoustic and inertial trackers [1].
The human body is often considered as a system of
rigid links connected by joints. Human body parts
are not actually rigid structures, but they are
customarily treated as such during studies of humanmotion. The human motion is often analyzed
through time series of the position of the body
segments or through time series of the motion of
the articulations.
First studies on the human walking were performed
by means of video capture, and the analysis of the
gait might be usable to identify persons.
Although all humans move in the same basic
pattern there are individual details in the relative
timing and magnitudes of the motions. These
variations have been studied much in clinical gait
analysis, which in most cases tries to distinctpathological gait from normal gait, and not to
identify humans.
3 A laboratory system for tests
In this paper the cable-based measuring system
CATRASYS (Cassino Tracking System) has been
used for the evaluation of human motion
characteristics.
CATRASYS has been conceived at LARM since1994 in order to evaluate the pose of a rigid body
during a large motion through on-line computation
of the Kinematics of the designed 3-2-1 cable-based
architecture. It determines the pose (position and
orientation) of a moving object by using trilateration
technique.
Details of CATRASYS are reported in [9-12]. In
this paper the new version of the CATRASYS is
used, it is able of pose/wrenches measurements and
monitoring, and it is shown in Figs. 1 and 2. It is
composed of a mechanical part, an
electronics/informatics interface unit, and a software
package. The mechanical part consists of a fixedbase, which has been named as Trilateral Sensing
Platform, and a moving platform, which has been
named as end-effector for CATRASYS. The two
platforms are connected by six cables, whose
tension is maintained by pulleys and spiral springs
that are fixed on the base. The new version of the
CATRASYS is able to measuring end-effector poses
and wrenches. In order to obtain this result, position
transducers Ti and force sensors Ci have been used,
as shown in Figs. 1 and 2a).
The end-effector for CATRASYS is the moving
platform operating as a coupling device since it
connects the cables of the six transducers to theextremity of a moving system as it is shown in Figs.
1 and 2b) through the so-called 3-2-1 configuration.
It allows the cables to track the system while it
moves. Signals from cable transducers are fed
though an amplified connector to the electronic
interface unit, which consists of a laptop for data
analysis.
In this paper a modified version for CATRASYS
measuring system is considered as an enhancement
of what has been preliminarily presented in [13,
14], in which force sensors can be suitably used to
obtain both pose and wrenches information. In the
mechanical design in Fig. 2 each force sensor hasbeen installed on the fixed platform with two
pulleys. The solution gives the advantage of
reducing inertial effects (which are due to the
cables only) and there is no need to have
miniaturized force sensors but commercial ones.
The pulleys have been sized to have a compact
system with a large orientation capability for each
cable and avoid the risk of cable folding/damaging.
Figure 1 shows a scheme and suitable installation of
the force sensors on the CATRASYS prototype.
The resulting system for tension monitoring is easyto install, compact and can be easily adapted to
cable tracking systems and cable-based parallel
manipulators.
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NI-DAQ
PC
LabView
T1 T2 T3 T4 T5 T6
C1 C2 C3 C4 C5 C6
End-Effector for
CaTraSys
FQH
TPS +/- 5 cc
Figure 1. A scheme of the new force-sensored
cable-based measuring system CATRASYS(Cassino Tracking System): Ti is cable transducer;
Ci is force sensor.
a)
b)
Figure 2. The new force-sensored cable-based
measuring system CATRASYS: a) prototype atLARM in Cassino; b) a scheme for trilateration.
4 Evaluation of human walking
Several experimental tests have been carried out
with the cable-based measuring system
CATRASYS. In particular, the configuration
scheme in Fig. 3, in which three cables meet in a
common attachment point H, has been adopted forthe experimental tests. We have chosen to
experimentally evaluate points placed at the ankle
and knee joints, therefore, by means three position
transducers and three force sensors it is possible to
determine the ankle point H trajectory and forces
F1, F2 and F3 measured by the force sensors. The
same approach has been used to measure a knee
point trajectory and forces. The kinetostatic model
to be used has been presented in a preliminary
version in [13]. Figure 4 shows an illustrative
example of the experimental tests that have been
carried out with several subjects with different
gender, age, and weight, as given in Tables I and II.The aim of the paper is to evaluate the human
walking characteristics by taking into account
factors that can influence the gait, such has:
different type of shoes, loads, and of course, height,
weight, gender. The experimental results in Fig. 5
refer to a test on a male subject, in particular, the
ankle trajectory and the force exerted by the leg end
point are measured. Figure 6 refers to the human
walking of a female subject.
Figure 3. A scheme for the experimental tests.
Figure 4. Experimental tests by using CATRASYS.
2
1
3
H
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a)
b)
c)
d)
Figure 5. Experimental results for the kinetostatic
analysis of the walking of a male subject: a) cables
lengths; b) ankle trajectory; c) cables forces; d)force magnitude F and components Fx, Fy and Fz.
a)
b)
c)
d)
Figure 6. Experimental results for the kinetostatic
analysis of the walking of a female: a) cables
lengths; b) ankle trajectory; c) cables forces; d)
force magnitude and components Fx, Fy and Fz.
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Several tests have been carried out, as reported in
Table I. In particular, gait charateristics have been
measured for several male and female subjects.
Comparisons among ankle and knee trajectories of
different types of subjects are reported in Figs. 7
and 8. It is worth to note that phisical features of
different subject can greatly influence the overallhuman walking, which can be analyzed by an ankle
point trajectory. Several tests have been also carried
out to investigate the influence of carrying a load
during the walking operation, as reported in Fig. 8.
A load of 6 kg is considered for the tests that are
summarized in Table II.
a)
b)
c)
Figure 7. Comparison of the ankle trajectory of: a)
male (bold line) and female (thin line) subjects; b)
tall (thin line) short (bold line) subjects; c) fat (thinline) and slim (bold line) subjects.
a)
b)
c)
Figure 8. Comparison of the ankle trajectory of: the
subject 9 in Table 2 a) without load (bold line) and
with (thin line) load; b) subject 3 without a load
(thin line) and with (bold line) a load; c) subject 10knee trajectory with a load (thin line) and without
(bold line) load; d) subject 3 knee trajectory.
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Experimental tests have been carried out for
investigating the influence of the shoes on gait
properties. In particular, for a female of 1.80 m tall,
with a heel 80 mm, a modification occurs of the
body slope of 25 deg, as shown in the scheme of
Fig. 8. A modification of the body posture can
produce different walking pattern but also pain inthe articulations and even permanent posture
modification [15]. Experimental tests are reported
in Figs. 9-11 for different shoes.
a) b) c)
Figure 8. A scheme for the shoe influence: a) flat
shoe; b) shot heel; c) high heel.
Figure 9. Experimental tests on a female subject
with a 110 mm heel shoe.
Figure 10. Experimental results of the ankle
trajectory for the human walking with a 10mm heel
(bold line), 80mm heel (dotted line) and 110 mmheel (thin line).
Experiemental tests have been also carried out by
considering different speeds of locomotion for the
same male subject. Experimental results are
reported in Figs. 12 and 1 for two average speeds of
5 and 8 km/h. As aspected both trajectories of ankle
and knee are
Figure 11. Experimental results of the knee
trajectory for the human walking with a 10mm heel
(bold line), 80mm heel (dotted line) and 110 mmheel (thin line).
Figure 12. Experimental results of the ankle
trajectory for the human walking with velocity of
4.56.5 km/h (bold line); -and 9.,511.5 km/h (thin
line).
Figure 13. Experimental results of the knee
trajectory for the human walking with velocity of
4.56.5 km/h (bold line); -and 9.,511.5 km/h (thinline).
25
45
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Figure 14 shows first experimental results for a
subject with knee and hip articulations problems. It
it worth to note the flight phase trajectory
modification, if compared with a healty subject, and
small vibrations. Indeed, the system can be further
used to analyze the normalcy of the operation
during the walking operation.
a)
b)Figure 14. Experimental results of a pathological
human gait: a) ankle trajectory; b) knee trajectory.
5 Conclusions
In this paper an experimental analysis is performed
of the human walking characteristics by means of acable-based measuring system. Several
experimental tests are reported for analyzing the
overall properties of the gait in terms of the ankle
and knee trajectories and forces, which are
commonly used as reference data in medical
physiotherapy practice. It has been experimentally
verified that characteristics such as age, gender,
weight and height can greatly influence the human
locomotion, as reported in the examples.
6 References
[1] Adrian M. J., Cooper J. M., Biomechanics ofHuman Movement, Second Ed., Brown and
Benchmark Ed., Dubuque, 1995.
[2] Vicon Motion Capture System, webpage:
http://www.vicon.com/, 2008.
[3] Optotrack portable metrology system: webpage:
http://www.ndigital.com/industrial/optotrakproserie
s-family.php, 2008.
[4] Bonato P., Wearable sensors/systems and theirimpact on biomedical engineering. IEEE
Engineering in Medicine and Biology Magazine,
22(3), pp. 1820, 2003.
[5] Moven inertial motion capture system: webpage:
http://www.moven.com/en/home_moven.php, 2008.
[6] Williams II R.L., Albus J.S., Bostelman R.V.,
3D Cable Based Cartesian Metrology System, Jnl of
Robotic Systems, 21(5), pp. 237-257, 2004.
[7] Yun X., Bachmann E. R., Design,
Implementation, and Experimental Results of a
Quaternion-Based Kalman Filter for Human Body
Motion Tracking, IEEE Trans. on Robotics, 22(6),
pp. 1216-1227, 2006.[8] Srinivasan M., Why Walk and Run: Energetic
Costs and Energetic Optimality in Simple
Mechanics-Based Models of a Bipedal Animal,
Ph.D. Dissertation, Cornell University, 2006.
[9] Ceccarelli M., Toti M.E., Ottaviano E.,
CATRASYS (Cassino Tracking System): A New
Measuring System for Workspace Evaluation of
Robots, 8th International Workshop on Robotics in
Alpe-Adria-Danube Region RAAD'99, Munich, pp.
19-24, 1999.
[10] Ottaviano E., Ceccarelli M., Toti M., Avila
Carrasco C., CaTraSys (Cassino Tracking System):
A Wire System for Experimental Evaluation of
Robot Workspace, Jnl of Robotics and
Mechatronics, 14(1), pp.78-87, 2002.
[11] Ottaviano E. Ceccarelli M., Sbardella F.,
Thomas F., Experimental Determination of
Kinematic Parameters and Workspace of Human
Arms, 11th International Workshop on Robotics in
Alpe-Adria-Danube Region RAAD 2002,
Balatonfured, pp.271-276, 2002.
[12] Thomas, F., Ottaviano E., Ros L., Ceccarelli
M., Performance Analysis of a 3-2-1 Pose
Estimation Device , IEEE Transactions on Robotics
and Automation, 21(3), pp.288-297, 2005.
[13] Palmucci F., Ottaviano E., Ceccarelli M., An
Application of CaTraSys, a Cable-Based Parallel
Measuring System for a Kinetostatic Analysis of
Human Walking, Proceedings of MUSME 2008,
the International Symposium on Multibody
Systems and Mechatronics San Juan, Paper n. 22-
MUSME08, 2008.
[14] Grande S., Experimental Analysis of theHuman Gait, Internal LARM report, University of
Cassino, 2008.
[15] Faivre A., Dahan M., Parratte B., Monnier G.,
Instrumented Shoes for Pathological Gait
Assessment, Jnl of Mechanics Research
Communications, 31, pp.627632, 2004.
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Table 1. Main characteristics of subjects under study.
Gait
Sex Ageheight[mm]
Mass[kg]
height y[mm]
Length x[mm]
Freq. f [Hz]
Subject 1 M 27 1780 78 123 440 0.79Subject 2 M 26 1800 72 115 550 0.76
Subject 3 M 23 1760 70 118 500 0.72
Subject 4 M 27 1800 77 90 380 0.65
Subject 5 M 24 1830 70 120 500 0.92
Subject 6 M 25 1650 55 140 550 0.88
Subject 7 M 22 1760 70 115 600 0.54
Subject 8 M 24 1830 60 115 500 0.77
Subject 9 M 21 1860 75 140 600 0.87
Subject 10 M 22 1760 85 115 550 0.72
Subject 11 M 21 1700 72 110 450 0.85
Subject 12 M 24 1780 80 112 500 0.63
Subject 13 M 22 1820 90 150 430 0.76Subject 14 M 25 1850 117 83 450 0.47
Subject 15 F 35 1680 57 100 500 0.84
Subject 16 F 35 1650 63 200 540 0.86
Subject 17 F 20 1750 63 85 440 0.87
Subject 18 F 20 1600 58 112 430 0.92
Subject 19 F 23 1660 67 120 550 0.93
Subject 20 F 23 1600 51 125 430 0.77
Subject 21 F 21 1750 60 110 510 0.73
Subject 22 F 23 1630 64 128 550 0.72
Subject 23 F 22 1700 65 110 450 0.82
Subject 24 F 20 1670 63 100 360 0.98
Subject 25 F 21 1730 61 95 470 0.87
Subject 26 F 21 1610 51 110 520 0.77
Subject 27 F 20 1700 55 130 590 0.83
Male mean 24 1784 77 118 500 0.74
Female mean 23 1672 60 117 488 0.84
Table 2. Main characteristics of the subjects for the experimental tests carrying a load (m=6 kg).
Gait Gait with load
i Sex AgeHeight[mm]
MassM
[kg]
h1[mm]
h2[mm] H
[mm]L
[mm]H
[mm]L [mm]
I=m/MH
[mm]L
[mm]
1 M 27 1720 64 420 440 119 429 113 424 0.09 7 5
2 M 23 1720 95 450 465 96 527 92 526 0.06 4 1
3 M 25 1850 117 465 400 101 457 103 488 0.05 -2 -31
4 M 24 1830 60 460 460 145 600 135 586 0.10 10 14
5 F 20 1670 63 400 400 135 531 116 514 0.10 19 17
6 F 25 1850 117 400 400 121 521 124 507 0.05 -3 14
7 F 23 1630 80 440 380 95 613 95 605 0.08 0 7
8 M 22 1760 70 450 420 117 488 111 493 0.09 6 -5
9 M 21 1860 75 640 660 156 720 144 688 0.08 13 32
mean 23 1766 82 458 447 120 543 115 537 0.08 6 6