36 a joint force position measurement system for accessibility quantification
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11-12/01/2010 Kick-off meeting Brussels, Belgium
A JOINT FORCE-POSITION MEASUREMENT SYSTEM FOR ACCESSIBILITY QUANTIFICATION M. Kirchner, M. Confalonieri, A. Paludet, F. Degasperi, M. Da Lio, M. De Cecco University of Trento, DIMS - Department of Mechanical and Structural Engineering – via Mesiano 77, 38100 Trento, Italy. mauro.dalio@unitn.it, mariolino.dececco@unitn.it
Matteo Kirchner
Michele Confalonieri
Alberto Paludet
Filippo Degasperi
Mauro Da Lio
Mariolino De Cecco
AEGIS Conference Brussels 28-30 November 2011
INTRODUCTION
2
A large variety of motor disabilities have
neuromuscular or cardiovascular cause. These
ultimately happen as reduced ability to control
movements.
From the functional point of view, several limitations
can be observed, ranging from muscle tone
functions to control of voluntary movements
(such as bradikinesia, akinesia, apraxia, etc.), to
involuntary movements (such as tremors, tics, etc.),
to loss of sensations related to muscles and
movements.
AEGIS Conference Brussels 28-30 November 2011
INTRODUCTION
3
These ultimately cause problems in
interacting with products, services and
environments encountered in all aspects of
daily life.
Those systems, intended for the consumer
market and the workplace, should be
designed to be accessible for all people
including those with special requirements,
such as older persons and persons with
disabilities.
AEGIS Conference Brussels 28-30 November 2011
INTRODUCTION – Clinical scales
4
To assess human functions, a large number of clinical
scales exist, specific for each disease: the Unified
Parkinson’s Disease Rating Scale, or the Gross Motion
Function Measure for Cerebral Palsy, etc.
However, clinical scales rely on the expertise of
examiners, are disease related. For these reasons,
several attempts have been made to use objective
indicators that can be derived from measurements.
Computerized assessment tools have been
proposed in several types of motor disabilities.
AEGIS Conference Brussels 28-30 November 2011
INTRODUCTION – Computerized tests
5
We may classify basically four types of tests,
depending on the type of task that is measured:
1) Point-to-point aiming tests, which assess movement
time, reaction, time, dwelling time and accuracy of
target achievement;
2) Continuous tracking tests, which assess motion
jerkiness and tracking errors (both lateral and
longitudinal deviations);
3) Hold tests, in which the ability to reject perturbance
forces is assessed;
4) Force control tests, which measure the ability to
achieve and control forces.
AEGIS Conference Brussels 28-30 November 2011
INTRODUCTION - Standards
6
On the side of standards, ISO/IEC Guide 71 introduces the
concept that taking care of the needs of older persons and
persons with disabilities is fundamental in developing
relevant International Standards for products and services
design.
Technical report ISO/TR 22411:2008 presents ergonomics
data and guidelines for applying ISO/IEC Guide 71.
It provides ergonomics data and knowledge about human
abilities like sensory, physical and cognitive, as well as
guidance on the accessible design of products, services and
environments.
AEGIS Conference Brussels 28-30 November 2011
INTRODUCTION - Standards
7
In this framework it is possible to find data about
hand/finger dexterity. Two subcategories that
regard the interaction with a 2D interface are listed.
One is “Data on hand steadiness”, the other “Grip
strength”.
Data about hand steadiness is defined as the
minimum hole diameter of a plate through which a
person can pass a pencil or needle without touching
the edge.
Grip strength data are given only for maximal-effort
contraction in clench grip that uses all fingers
wrapped around the controlled object.
AEGIS Conference Brussels 28-30 November 2011
TOUCH INTERACTION
8
Touch sensing interfaces have rapidly grown in the
last decade and several new features have been
added and are going to appear
The 3M MicroTouch™ Capacitive
TouchSense® System (MCT
System) provides tactile feedback
effects for on-screen, video
buttons so users actually "feel"
like they are depressing
mechanical buttons.
AEGIS Conference Brussels 28-30 November 2011
TOUCH INTERACTION
Magic Trackpad form Apple is aMulti-Touch trackpad designed
to work with the Mac Desktop computers
click scroll swipe rotate
9
AEGIS Conference Brussels 28-30 November 2011
TOUCH INTERACTION
10
Korea - Advanced Institute of Science and Technology
Similar sliding gestures may have different meanings when
they are performed with changing force intensity. Touch
screens, however, fail to properly distinguish those
intensities due to their inability to sense variable pressures.
For the above reason they developed a touch screen
enabled by distinguishing normal and tangential forces
that allows new possibilities for gesture recognition on a
touch screen.
AEGIS Conference Brussels 28-30 November 2011
Standards – deficiencies in providing
indications for interaction dexterity
11
At least data about the following are lacking:
- path/trajectory following (with finger, mouse, etc)
- the ability to achieve and control different level of
forces
- position/force coordination issues
Furthermore hand steadiness is covered only for a
very peculiar task
The above are addressed by the “Force Panel”
and the specific tests developed
AEGIS Conference Brussels 28-30 November 2011
FORCE PANEL – The instrument
The instrument is composed of the following:
an LCD
a resistive touch panel
three force transducers
an embedded control system
an interface with a PC
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AEGIS Conference Brussels 28-30 November 2011
Point to point motion task
13
Measures the following:
• Reaction time
• Movement time
• Path deviation in point to point motion
• Dwelling Percentage Time in Target
AEGIS Conference Brussels 28-30 November 2011
Subject 1: mild hemiparesis
[mm]
[mm
]
14
AEGIS Conference Brussels 28-30 November 2011
[mm]
[mm
]
15
Subject 3: severe hemiparesis
not enough force
AEGIS Conference Brussels 28-30 November 2011
Subject 1
Time outside
target [ms]
Movement
Time [ms]
Reaction
Time [ms]
Path dev iation
[mm]
target 1 0 1375 327 2.8
target 2 0 1484 405 6.3
target 3 0 1343 406 4.9
target 4 0 1405 312 8.9
target 5 250 1202 297 2.3
target 6 0 1375 343 4.1
target 7 0 1266 280 4.3
Subject 3
Time outside
target [ms]
Movement
Time [ms]
Reaction
Time [ms]
Path dev iation
[mm]
target 1 983 1546 31 2.6
target 2 0 2638 31 2.5
target 3 0 2185 546 7.0
target 4 452 2295 515 5.8
target 5 110 2466 343 5.1
target 6 31 3496 63 5.9
target 7 702 2373 874 17.1
Subject 1: mild hemiparesis
Subject 3: severe hemiparesis
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AEGIS Conference Brussels 28-30 November 2011
Continuous tracking tasks
17
Measures the following:
• Percentage time in target
• Deviation to path
• Deviation to trajectory
AEGIS Conference Brussels 28-30 November 2011
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Subject 1: mild
hemiparesis
Subject 3: severe
hemiparesis
Subject
RMS deviation to
path [mm]
Mean target to finger
(trajectory) deviation
[mm]
Percentage of
time outside
the target [%]
1 10.9 2.2 9
3 26.0 4.2 36
AEGIS Conference Brussels 28-30 November 2011
FORCE PANEL –
HUMAN’S TRANSFER FUNCTION
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AEGIS Conference Brussels 28-30 November 2011
Transfer functions have been used to model how
human beings control several types of plants, for
example the lane keeping task in automobiles
(Kondo-like models) or route keeping in aircraft.
The transfer function used is the following:
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H 1 i Z1 i P
1
1 2i /N iN
2 eD i
Vertical line
horizontal trajectory
Finger horizontal
position
H
AEGIS Conference Brussels 28-30 November 2011
Measured quantities:
tau: delay, corresponding to the reaction time
H(w): frequency transfer function in trajectory
following
rms: root mean square error of the steady state
reached with respect to the reference (an estimate
of the reached accuracy)
21
AEGIS Conference Brussels 28-30 November 2011
Example of an estimated transfer function
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Some shots of real and simulated data with the
estimated model
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To simulate the lane following for a bike rider game
(in this way the game accessibility can be evaluated)
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AEGIS Conference Brussels 28-30 November 2011
Position-Force tracking tasks
25
Measures the following:
• Position MSE
• Force MSE
AEGIS Conference Brussels 28-30 November 2011
Example of measurements
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AEGIS Conference Brussels 28-30 November 2011
Thanks for your attention!
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