ABSTRACT There is a great interest in exploring the proprieties of the sense of the touch, its de... more ABSTRACT There is a great interest in exploring the proprieties of the sense of the touch, its detailed knowledge in fact is a key issue in the area of robotics, haptics and human-machine interaction. In this paper, the authors focus their attention on a novel measurement method for the assessment of the tactile stiffness based on a original test rig; tactile stiffness is defined as the ratio between force, exerted by the finger, and the displacement of the finger tip operated during the test. To reach this scope, the paper describes a specific experimental test-rig used for the evaluation of subject tactile sensitivity, where finger force applied during tests as well as displacement and velocity of displacement, operated by the subject under investigation, are measured. Results show that tactile stiffness is linear respect to stimuli spatial difference (which is proportional to the difficulty to detect the variation of them). In particular, it has been possible to relate the force and displacement measured during the tests. The relationship between the response of the subject to the grating, velocity and force is determined. These results permit to carry out the further experimental tests on the same subject avoiding the use of a load cell and therefore simplifying the measurement test rig and data post-processing. Indeed, the first aspect (use of a load cell) can be relevant, because the grating positions are different, requiring a specific re-calibration and setting before each trial; while the second aspect allows simplify the test rig complexity and the processing algorithm.
— The computation of skin forces and deformations for tactile rendering requires an accurate mode... more — The computation of skin forces and deformations for tactile rendering requires an accurate model of the ex-tremely nonlinear behavior of the skin. In this work, we inves-tigate the characterization of finger mechanics with the goal of designing accurate nonlinear models for tactile rendering. First, we describe a measurement setup that enables the acquisition of contact force and contact area in the context of controlled finger indentation experiments. Second, we describe an optimization procedure that estimates the parameters of strain-limiting deformation models that match best the acquired data. We show that the acquisition setup allows the measurement of force and area information with high repeatability, and the estimation method reaches nonlinear models that match the measured data with high accuracy. I.
With interactive maps a person can manage to find the way from one point to another, using an all... more With interactive maps a person can manage to find the way from one point to another, using an allocentric perspective (e.g. Google Maps), but also looking at a location as from the inside of the map with an egocentric perspective (e.g. Google Street View). Such experience cannot be performed with tactile maps, mostly explored from a top-view. To solve this, we built a system with two different but complementary devices. When coupled, they can provide both allocentric and egocentric spatial information to support the exploration of interactive tactile maps. To show the potential of the system, we built a blind treasure hunt.
Background In this work, we present a novel sensory substitution system that enables to learn thr... more Background In this work, we present a novel sensory substitution system that enables to learn three dimensional digital information via touch when vision is unavailable. The system is based on a mouse-shaped device, designed to jointly perceive, with one finger only, local tactile height and inclination cues of arbitrary scalar fields. The device hosts a tactile actuator with three degrees of freedom: elevation, roll and pitch. The actuator approximates the tactile interaction with a plane tangential to the contact point between the finger and the field. Spatial information can therefore be mentally constructed by integrating local and global tactile cues: the actuator provides local cues, whereas proprioception associated with the mouse motion provides the global cues. Methods The efficacy of the system is measured by a virtual/real object-matching task. Twenty-four gender and age-matched participants (one blind and one blindfolded sighted group) matched a tactile dictionary of vir...
ABSTRACT Research on tactile sensitivity has been conducted since the last century and many devic... more ABSTRACT Research on tactile sensitivity has been conducted since the last century and many devices have been proposed to study in detail this sense through experimental tests. The sense of touch is essential in every-day life of human beings, but it can also play a fundamental role for the assessment of some neurological disabilities and pathologies. In fact, the level of tactile perception can provide information on the health state of the nervous system. In this paper, authors propose the design and development of a novel test apparatus, named DITA (Dynamic Investigation Test-rig on hAptics), aiming to provide the measurement of the tactile sensitivity trough the determination of the Just Noticeable Difference (JND) curve of a subject. The paper reports the solution adopted for the system design and the results obtained on the set of experiments carried out on volunteers.
ABSTRACT Sensing in humans is carried out in different modalities, among them, the touch is essen... more ABSTRACT Sensing in humans is carried out in different modalities, among them, the touch is essential in every-day life allowing most of all the manual activities. Less known is the fundamental role in the screening of some neurological diseases. In fact it is possible, trough the assessment of the level of tactile perception, to evaluate during clinical/medical diagnosis the nervous systemhealth state. It is therefore fundamental to determine valid measurement procedures aiming to this task. The analysis has started with the investigation of tactile frequency sensibility, on healthy subjects, who examined tactile stimuli with devices called arrays. Arrays are formed by passive pins, which follow the shape of the stimuli. There were different arrays depending on the number of pins on them. The only task of subjects was to recognize the higher between couples of stimuli (one grating) with different frequency. The aim of these tests is that of creating a diagnostic scale for tactile neurodegenerative syndromes and diseases. Results show a significant role of pins density with a performance that falls when pins distance is higher than 1 mm. Preliminary clinical tests on 3 patients with tunnel carpal syndrome suggest positive development for use as a diagnostic tool.
Tactile maps are efficient tools to improve spatial understanding and mobility skills of visually... more Tactile maps are efficient tools to improve spatial understanding and mobility skills of visually impaired people. Their limited adaptability can be compensated with haptic devices which display graphical information, but their assessment is frequently limited to performance-based metrics only which can hide potential spatial abilities in O&M protocols. We assess a low-tech tactile mouse able to deliver three-dimensional content considering how performance, mental workload, behavior, and anxiety status vary with task difficulty and gender in congenitally blind, late blind, and sighted subjects. Results show that task difficulty coherently modulates the efficiency and difficulty to build mental maps, regardless of visual experience. Although exhibiting attitudes that were similar and gender-independent, the females had lower performance and higher cognitive load, especially when congenitally blind. All groups showed a significant decrease in anxiety after using the device. Tactile graphics with our device seems therefore to be applicable with different visual experiences, with no negative emotional consequences of mentally demanding spatial tasks. Going beyond performance-based assessment, our methodology can help with better targeting technological solutions in orientation and mobility protocols.
ABSTRACT There is a great interest in exploring the proprieties of the sense of the touch, its de... more ABSTRACT There is a great interest in exploring the proprieties of the sense of the touch, its detailed knowledge in fact is a key issue in the area of robotics, haptics and human-machine interaction. In this paper, the authors focus their attention on a novel measurement method for the assessment of the tactile stiffness based on a original test rig; tactile stiffness is defined as the ratio between force, exerted by the finger, and the displacement of the finger tip operated during the test. To reach this scope, the paper describes a specific experimental test-rig used for the evaluation of subject tactile sensitivity, where finger force applied during tests as well as displacement and velocity of displacement, operated by the subject under investigation, are measured. Results show that tactile stiffness is linear respect to stimuli spatial difference (which is proportional to the difficulty to detect the variation of them). In particular, it has been possible to relate the force and displacement measured during the tests. The relationship between the response of the subject to the grating, velocity and force is determined. These results permit to carry out the further experimental tests on the same subject avoiding the use of a load cell and therefore simplifying the measurement test rig and data post-processing. Indeed, the first aspect (use of a load cell) can be relevant, because the grating positions are different, requiring a specific re-calibration and setting before each trial; while the second aspect allows simplify the test rig complexity and the processing algorithm.
— The computation of skin forces and deformations for tactile rendering requires an accurate mode... more — The computation of skin forces and deformations for tactile rendering requires an accurate model of the ex-tremely nonlinear behavior of the skin. In this work, we inves-tigate the characterization of finger mechanics with the goal of designing accurate nonlinear models for tactile rendering. First, we describe a measurement setup that enables the acquisition of contact force and contact area in the context of controlled finger indentation experiments. Second, we describe an optimization procedure that estimates the parameters of strain-limiting deformation models that match best the acquired data. We show that the acquisition setup allows the measurement of force and area information with high repeatability, and the estimation method reaches nonlinear models that match the measured data with high accuracy. I.
With interactive maps a person can manage to find the way from one point to another, using an all... more With interactive maps a person can manage to find the way from one point to another, using an allocentric perspective (e.g. Google Maps), but also looking at a location as from the inside of the map with an egocentric perspective (e.g. Google Street View). Such experience cannot be performed with tactile maps, mostly explored from a top-view. To solve this, we built a system with two different but complementary devices. When coupled, they can provide both allocentric and egocentric spatial information to support the exploration of interactive tactile maps. To show the potential of the system, we built a blind treasure hunt.
Background In this work, we present a novel sensory substitution system that enables to learn thr... more Background In this work, we present a novel sensory substitution system that enables to learn three dimensional digital information via touch when vision is unavailable. The system is based on a mouse-shaped device, designed to jointly perceive, with one finger only, local tactile height and inclination cues of arbitrary scalar fields. The device hosts a tactile actuator with three degrees of freedom: elevation, roll and pitch. The actuator approximates the tactile interaction with a plane tangential to the contact point between the finger and the field. Spatial information can therefore be mentally constructed by integrating local and global tactile cues: the actuator provides local cues, whereas proprioception associated with the mouse motion provides the global cues. Methods The efficacy of the system is measured by a virtual/real object-matching task. Twenty-four gender and age-matched participants (one blind and one blindfolded sighted group) matched a tactile dictionary of vir...
ABSTRACT Research on tactile sensitivity has been conducted since the last century and many devic... more ABSTRACT Research on tactile sensitivity has been conducted since the last century and many devices have been proposed to study in detail this sense through experimental tests. The sense of touch is essential in every-day life of human beings, but it can also play a fundamental role for the assessment of some neurological disabilities and pathologies. In fact, the level of tactile perception can provide information on the health state of the nervous system. In this paper, authors propose the design and development of a novel test apparatus, named DITA (Dynamic Investigation Test-rig on hAptics), aiming to provide the measurement of the tactile sensitivity trough the determination of the Just Noticeable Difference (JND) curve of a subject. The paper reports the solution adopted for the system design and the results obtained on the set of experiments carried out on volunteers.
ABSTRACT Sensing in humans is carried out in different modalities, among them, the touch is essen... more ABSTRACT Sensing in humans is carried out in different modalities, among them, the touch is essential in every-day life allowing most of all the manual activities. Less known is the fundamental role in the screening of some neurological diseases. In fact it is possible, trough the assessment of the level of tactile perception, to evaluate during clinical/medical diagnosis the nervous systemhealth state. It is therefore fundamental to determine valid measurement procedures aiming to this task. The analysis has started with the investigation of tactile frequency sensibility, on healthy subjects, who examined tactile stimuli with devices called arrays. Arrays are formed by passive pins, which follow the shape of the stimuli. There were different arrays depending on the number of pins on them. The only task of subjects was to recognize the higher between couples of stimuli (one grating) with different frequency. The aim of these tests is that of creating a diagnostic scale for tactile neurodegenerative syndromes and diseases. Results show a significant role of pins density with a performance that falls when pins distance is higher than 1 mm. Preliminary clinical tests on 3 patients with tunnel carpal syndrome suggest positive development for use as a diagnostic tool.
Tactile maps are efficient tools to improve spatial understanding and mobility skills of visually... more Tactile maps are efficient tools to improve spatial understanding and mobility skills of visually impaired people. Their limited adaptability can be compensated with haptic devices which display graphical information, but their assessment is frequently limited to performance-based metrics only which can hide potential spatial abilities in O&M protocols. We assess a low-tech tactile mouse able to deliver three-dimensional content considering how performance, mental workload, behavior, and anxiety status vary with task difficulty and gender in congenitally blind, late blind, and sighted subjects. Results show that task difficulty coherently modulates the efficiency and difficulty to build mental maps, regardless of visual experience. Although exhibiting attitudes that were similar and gender-independent, the females had lower performance and higher cognitive load, especially when congenitally blind. All groups showed a significant decrease in anxiety after using the device. Tactile graphics with our device seems therefore to be applicable with different visual experiences, with no negative emotional consequences of mentally demanding spatial tasks. Going beyond performance-based assessment, our methodology can help with better targeting technological solutions in orientation and mobility protocols.
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Papers by Mariacarla Memeo