Application of Tactile Perception Enhancement

Sylvain Cardin
EPFL, 2010
Thèse EPFL

Résumé

Surrounding environment is mainly perceived through sight and hearing. Our sense of touch is mostly dedicated to explore the surface of objects using hands and fingers. Tactile sensitivity of the body skin is rather limited in common life, however this represents a viable channel to pass information. The goal of this thesis is to study the added value of tactile stimulation to increase perception in specific application contexts. First, we define our motivation and approach regarding existing tactile systems and scientific knowledge available. In order to study tactile influence in different applications, we decided to build our own hardware and software blocks based on vibrotactile actuators driven by embedded electronics communicating with an external computer. Our objective was to explore different research directions by assessing added value in term of perception for tactile stimulation. The first topic we study tends to replace one of our senses, sight, by a metaphorical vibrotactile feedback representing the distance to close range object. We developed an electronic travel aid for visually impaired people, based on vibration motors and sonar. We assessed its ability to evolve and avoid obstacles in our surrounding environment. The next step consists in determining if such a principle can be applied to pass information about the environment within the field of teleoperation. Indeed, controlling a distant unmanned aerial vehicle is a difficult task due to limited visual feedback and absence of proprioceptive cue to feel the motion of the aircraft. Applying vibrotactile feedback that represents the effect of the wind seems to be an interesting approach for mental perception of the behavior of a remote controlled blimp. Wind is a natural phenomenon that we feel through our somatosensory system. At this point we wondered about the need of a metaphorical representation using vibrotactile stimulation. Even if it is rather easy to recreate wind using a fan, there is a lack of proper hardware to recreate directional wind. We built the first "wearable" haptic wind device for virtual reality enhancement and proved its usability to pass relevant directional information. Giving a direction in 3D space requires that the actuators are not located on the same plane as in our previous systems. We developed a wireless vibrotactile jacket containing 32 vibration motors and present its added value for a 3D searching space exercise in virtual environment, in correlation with visual and auditory cues. The second half of this document treats about development and application of a vibrotactile system in the challenging "Solar Impulse" project, aiming at performing a flight around the world relying only on renewable energy. A prototype aircraft has been built pushing forward the limits of the feasible in solar energy, composite materials, power management and human factor. As scientific consultant, our mission was to build an intelligent jacket in order to achieve symbodic relation between man and machine. A Symbodic system (SYMbiotic BODies) is a wearable device that supports symbiotic communication between the bodies of the pilot and of the machine. We proposed then a promising concept on how to improve awareness of the aircraft behavior. Passing from research concept to a concrete flying prototype is not an easy task, especially in terms of end-user acceptance: habits are strong for experienced pilot. But such an extraordinary airplane leads to some extraordinary aerodynamical behavior and the need of new visualization instruments. We developed an alert system for long flight duration based on the principle of the rumble strip installed on side of worldwide motor ways. Extensive tests have been performed by putting a subject in command of a highly realistic flight simulator for 48 hours straight. We showed that such system produces significant improvements of piloting performance under heavy sleep deprivation constraints.

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https://infoscience.epfl.ch/record/147964?ln=fr

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Sylvain Cardin
EPFL, 2010
Thèse EPFL

Résumé

Official source

https://infoscience.epfl.ch/record/147964?ln=fr

À propos de ce résultat

Concepts associés (48)

Concepts associés

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Publications associées (25)

Publications associées

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Wearable multimodal tactile interfaces for augmenting haptic perception

Simon Gallo

Haptic feedback has been used to faithfully restitute the haptic sense lacking during telemanipulation, but also for providing auxiliary information via the haptic channel to restore functional perception of missing or damaged senses, e.g. sensory substitution for the visually impaired. Yet, despite the growing number of applications that would benefit from haptic feedback, its penetration rate remains low. We have identified three under-researched features of haptic feedback that we believe are necessary to break the bottleneck: multimodality, thermal feedback and wearability. Indeed, while haptic perception results from the integration of multiple somatosensory inputs, the interactions between haptic modalities have rarely been investigated. Thermal feedback is an ideal candidate to explore these interactions as skin temperature is known to modulate the sensitivity of skin receptors. Finally, although haptic perception is distributed over the entire body, most multimodal haptic devices are still bulky and rigid, thus limiting their usage to specific body parts and applications. As the integration of multiple feedback modalities into a flexible display is complex, the benefits of these three features need to be demonstrated. This motivated the developments presented in this thesis. First, we miniaturized and integrated thermal feedback in multisensory platforms to investigate its role in conveying non-sensory information and modulating tactile perception. The first study showed that users are able to distinguish the temperature difference between two adjacent thermal stimuli presented under the fingertip by a high-density thermal display, highlighting the potential of miniaturized displays to deliver thermally-encoded information through small skin areas. A second study showed that modifying the skin temperature yielded changes in the precision of stiffness judgments up to 22.3%, suggesting that thermal feedback can be used to modulate the perception of complex haptic percepts. Moving towards complete wearability, we introduced a wearable multimodal display that matches the skin curvature to deliver thermo-tactile cues optimally, as supported by the high usersâ identification rates of simulated materials. Subsequently, we developed a portable hydraulic actuation that generates multimodal tactile feedback in remote 3D-printed flexible displays, paving the way to truly versatile wearable multimodal displays. Finally, a tactile suit remapping tactile and proprioceptive sensations from the virtual legs of an avatar onto the upper limbs of paraplegic patients is developed. We show that the patients were able to perceive the position of the virtual legs based on tactile feedback alone, that the use of tactile feedback in synchrony with the avatarâs walk changed the perception of the boundaries of their body, and that the modulation of the tactile stimulation induced a robust sensation of walking on different floors. These results demonstrate the potential of wearable tactile displays to create perceptual orthoses. In this work, we have developed the tools to deliver a multimodal tactile stimulation using wearable thermo-tactile displays and have shown how their unique features can impact fields such as surgical and rehabilitation robotics. These findings encourage the future development of wearable multimodal tactile displays taking advantage of the synergies between haptic modalities to improve teleoperation and sensory rehabilitation.

EPFL2016

Chargement

Two-handed haptic feedback in generic virtual environments

Renaud Ott

Since [years] we hear about Virtual Reality as a discipline that could potentially provide benefits to many applications. Basically, the principle of Virtual Reality consists in stimulating user senses in order to give the impression to be in another place which they can discover and interact with. Today, most virtual reality systems create realistic visual and auditive environments. However the interaction with these environments can not be considered as natural. Indeed, we often use devices such as mouse, keyboard or joystick to move or manipulate them. These paradigms of interaction are in fact metaphors, which are not similar to reality. In some situations they are practical and efficient. However, the lack of intuitiveness sometimes makes them limited or simply ineffective. To overcome this, researchers can use Haptic Devices. They are designed to simulate what is commonly called the "sense of touch", which includes more specifically, tactile, pain sense, thermal sense, and proprioception. Proprioception is knowledge gained by the perception of the relative member's position of the human body. In this thesis, we particularly focus on the simulation of proprioception. There are two advantages of such haptic devices. First, they can give the user more information on the nature of virtual objects (size, weight, finish, rigidity, etc.). Second, they can provide interaction paradigms that are closer to reality (three-dimensional interaction in a three-dimensional world). However, haptic device mechanics is complex. Moreover, proprioception is a sense that covers the entire body which is a rather large surface. For this reason, haptic devices usually apply force feedback on a very small portion of the body, such as fingertip. In addition to this hardware constraint, haptic research also faces software constraints. Indeed, a haptic application requires many computer resources in order to perform collision detection, dynamic animation of objects, and force feedback computation. Moreover, this should be done at a refresh rate that is much higher than the visualization for producing a convincing result. In the first part of this thesis, we propose to increase realism and complexity of haptic applications. To achieve this goal, we use a state-of-the-art commercial device which allows to acquire the posture and position of both hands, and to apply forces on the fingertips and wrists. We propose techniques to calibrate and improve the comfort of these kinds of devices in order to integrate them into Virtual Environments. However, a two-handed haptic device do not presents only advantages. Indeed, It is much more complicated to compute forces on two hand models, than on a single point or fingertip. For this reason, in this thesis, we propose a framework to optimize this computation. Thanks to it, we can create Virtual Environments in which an object is graspable and dynamically animated by the laws of physics. When the object is seized by both hands, the haptic rendering engine realistically computes the forces on both exoskeletons. The efficiency of our rendering permits to apply these techniques to complex environments that have a significant number of objects. But the existing visual Virtual Environments are much more detailed than the ones seen in common haptic applications. In this thesis, we aim at reducing this gap. One of the problems is that these quality environments usually do not include specific haptic object properties, such as mass or material. We thus propose a software allowing even non-professional to quickly and easily add this information to an environment. Our results show that this haptic rendering engine does not suffer from the large quantity of objects. They demonstrate that we have an efficient framework for integrating a two-handed haptic interface into a generic virtual environment. In the second part, we evaluate the potential of these kinds of Virtual Reality systems in more detail. While most applications can in theory take advantage of haptic devices, the practice shows that it is not always the case. Indeed, with experience, some metaphorical interaction paradigms remain more powerful than realistic ones. We thus present and study the integration of our two-handed haptic interface in a variety of applications. Evaluations show that depending on the application, it is not appropriate to reproduce reality: in teleoperation, for instance, simulating a virtual haptic steering wheel is less efficient than providing a force gesture interface. On the other hand, in virtual learning, the power of two-handed haptic manipulation is fully exploited and presents great advantages over standard techniques.

EPFL2009

Chargement

Robotic teleoperation is fundamental to augment the resilience, precision, and force of robots with the cognition of the operator. However, current interfaces, such as joysticks and remote controllers, are often complicated to handle since they require cognitive effort and learned skills. Wearable interfaces can enable more natural and intuitive interactions with robots, which would make robotic teleoperation accessible to a larger population of users for demanding tasks, such as manipulation or search-and-rescue. The aim of this thesis is to explore solutions to simplify our interactions with robots promoting their access to a broader range of the population. To achieve this, we are presenting a soft upper body exoskeleton, called the FlyJacket, for the bidirectional control of drones. Drones can greatly benefit us as they extend our perception and range of action. The exoskeleton controls a drone by recording torso movement and, through embedded haptic feedback devices, renders either kinesthetic guidance to improve the flight performance or tactile feedback to render the sensation of flying. We developed and tested an interface to control both a simulated and a real drone. The FlyJacket is a soft exoskeleton with arm support conceived to address the challenges of adapting to different morphologies and supporting the user during flight to prevent fatigue. We demonstrated that this novel interface allowed more consistent performance than when performing the same task with a remote controller and users felt more immersed into the flight. Interacting with a robot can be greatly enhanced by having multiple channels of sensorial feedback to increase the awareness of the operator. Information on the state of the drone can be intuitively rendered with haptic feedback. To create this bidirectional interaction with the drone, the two types of haptic feedback - kinesthetic and tactile - have been explored. Kinesthetic feedback was implemented with a cable-driven system to give guidance to the userâs torso position. Performing user studies, we could determine that the embedded guidance improved the flight performance and that a quadratically shaped force feedback curve was the most adequate profile to guide the user. We also established the minimal force difference, defined the perceived magnitude of this system and studied the learning process of users. Tactile feedback was investigated to render the sensation of flying by enhancing flight awareness, realism and immersion. To this end, we developed and embedded a new type of soft actuator that was compliant and lightweight such that it remained wearable and portable. Four devices, placed on the torso, provided feedback by compressing closed air pouches against the skin rendering the sensation of air pressure. A mechanical model and simulation of the pouch device were developed to determine appropriate parameters. We evaluated whether it conveyed useful information to the user and whether it enhanced the experience of flying. We demonstrated that users were able to understand the direction of the cues without prompting, could distinguish the cues quickly, and do so with high accuracy. The device was also used in a simulated flight task and users indicated that it increased the flight realism. We believe that the contributions of this thesis provides insights to the design of intuitive interfaces for human-robot interaction and increases their accessibility to a wider range of the population.

EPFL2019

Chargement

Two-handed haptic feedback in generic virtual environments

Renaud Ott

EPFL2009

Wearable multimodal tactile interfaces for augmenting haptic perception

Simon Gallo

EPFL2016

EPFL2019