Evaluation of Human Walking

8/3/2019 Evaluation of Human Walking

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3rdInternational Congress Design and Modelling of Mechanical Systems CMSM2009 Paper n. 43

March 16-18, 2009 Hammamet, Tunisia 1

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

Evaluation of Human Walking

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