119 research outputs found
Développement d'une unité de valves motorisées et algorithme de transition pour actionnement hydrostatique bimodal d'une jambe robotique
Les robots mobiles, tels que les exosquelettes et les robots marcheurs, utilisent des actionneurs qui doivent satisfaire Ă une large plage de requis de force et de vitesse. Par exemple, pour le cycle de marche dâune jambe robotique, la phase dâappui nĂ©cessite une force Ă©levĂ©e tandis que la phase de balancement requiert une grande vitesse. Pour satisfaire ces requis opposĂ©s, le dimensionnement dâun systĂšme dâactionnement traditionnel Ă rapport de rĂ©duction unique conduit gĂ©nĂ©ralement Ă un moteur Ă©lectrique lourd, surdimensionnĂ© et Ă une faible efficacitĂ© Ă©nergĂ©tique. Ainsi, lâalternative explorĂ©e est une architecture hydrostatique Ă deux vitesses oĂč des valves motorisĂ©es sont utilisĂ©es pour reconfigurer dynamiquement le systĂšme entre deux modes de fonctionnement : fort ou rapide. La complexitĂ© rĂ©side dans le choix dâune technologie de valve lĂ©gĂšre ainsi que dans le dĂ©veloppement dâun algorithme de contrĂŽle permettant de rĂ©aliser les transitions de maniĂšre rapide et fluide. Un prototype dâune unitĂ© de valves motorisĂ©es est conçu et intĂ©grĂ© dans lâarchitecture hydrostatique complĂšte de lâactionneur et un banc dâessai dâune jambe robotique est fabriquĂ©. Trois stratĂ©gies de contrĂŽle des moteurs sont comparĂ©es lors du changement de mode : une vitesse constante, une diminution de vitesse et une rĂ©duction du courant. La mĂ©thode choisie, le contrĂŽle en courant, est ensuite utilisĂ©e pour la dĂ©monstration des phases dâappui et de balancement de la jambe robotique. Par cette mĂ©thode, il est possible dâeffectuer des transitions rapides, de maintenir une force suffisante et de minimiser les oscillations qui surviennent lors du contact avec le sol. Ces travaux offrent donc un premier point de comparaison au niveau du choix de valves, de la masse, de la vitesse dâactionnement et de la stratĂ©gie de contrĂŽle
Modeling Emotional Valence Integration From Voice and Touch
In the context of designing multimodal social interactions for HumanâComputer Interaction and for ComputerâMediated Communication, we conducted an experimental study to investigate how participants combine voice expressions with tactile stimulation to evaluate emotional valence (EV). In this study, audio and tactile stimuli were presented separately, and then presented together. Audio stimuli comprised positive and negative voice expressions, and tactile stimuli consisted of different levels of air jet tactile stimulation performed on the arm of the participants. Participants were asked to evaluate communicated EV on a continuous scale. Information Integration Theory was used to model multimodal valence perception process. Analyses showed that participants generally integrated both sources of information to evaluate EV. The main integration rule was averaging rule. The predominance of a modality over the other modality was specific to each individual
Optically Sensorized Tendons for Articulate Robotic Needles
This study proposes an optically sensorized tendon composed of a 195 ”m diameter, high strength, polarization maintaining (PM) fiber Bragg gratings (FBG) optical fiber which resolves the cross-sensitivity issue of conventional FBGs. The bare fiber tendon is locally reinforced with a 250 ”m diameter Kevlar bundle enhancing the level of force transmission and enabling high curvature tendon routing.
The performance of the sensorized tendons is explored in terms of strength (higher than 13N for the bare PM-FBG fiber tendon, up to 40N for the Kevlar-reinforced tendon under tensile loading), strain sensitivity (0.127 percent strain per newton for the bare PM-FBG fiber tendon, 0.04 percent strain per newton for the Kevlar-reinforced tendon), temperature stability, and friction-independent sensing behavior.
Subsequently, the tendon is instrumented within an 18 Ga articulate NiTi cannula and evaluated under static and dynamic loading conditions, and within phantoms of varying stiffness for tissue-stiffness estimation. The results from this series of experiments serve to validate the effectiveness of the proposed tendon as a bi-modal sensing and actuation component for robot-assisted minimally invasive surgical instruments
Effects of Electrode Materials and Compositions on the Resistance Behavior of Dielectric Elastomer Transducers
Dielectric elastomer (DE) transducers possess various advantages in comparison to alternative actuator technologies, such as, e.g., electromagnetic drive systems. DE can achieve large
deformations, high driving frequencies, and are energy efficient. DEs consist of a dielectric membrane
sandwiched between conductive electrodes. Electrodes are especially important for performance,
as they must maintain high electrical conductivity while being subjected to large stretches. Low
electrical resistances allow faster actuation frequencies. Additionally, a rate-independent, monotonic,
and hysteresis-free resistance behavior over large elongations enables DEs to be used as resistive
deformation sensors, in contrast to the conventional capacitive ones. This paper presents a systematic
study on various electrode compositions consisting of different polydimethylsiloxane (PDMS) and
nano-scaled carbon blacks (CB). The experiments show that the electrode resistance depends on the
weight ratio of CB to PDMS, and the type of CB used. At low ratios, a high electrical resistance
accompanied by a bimodal behavior in the resistance time evolution was observed, when stretching
the electrodes cyclic in a triangular manner. This phenomenon decreases with increasing CB ratio.
The type of PDMS also influences the resistance characteristics during elongation. Finally, a physical
model of the observed phenomenon is presented
Multimodal Human-Machine Interface For Haptic-Controlled Excavators
The goal of this research is to develop a human-excavator interface for the hapticcontrolled excavator that makes use of the multiple human sensing modalities (visual, auditory haptic), and efficiently integrates these modalities to ensure intuitive, efficient interface that is easy to learn and use, and is responsive to operator commands. Two empirical studies were conducted to investigate conflict in the haptic-controlled excavator interface and identify the level of force feedback for best operator performance
A Systematic Review of Weight Perception in Virtual Reality: Techniques, Challenges, and Road Ahead
Weight is perceived through the combination of multiple sensory systems, and a wide range of factors â including touch, visual, and force senses â can influence the perception of heaviness. There have been remarkable advancements in the development of haptic interfaces throughout the years. However, a number of challenges limit the progression to enable humans to sense the weight in virtual reality (VR). This article presents an overview of the factors that influence how weight is perceived and the phenomenon that contributes to various types of weight illusions. A systematic review has been undertaken to assess the development of weight perception in VR, underlying haptic technology that renders the mass of a virtual object, and the creation of weight perception through pseudo-haptic. We summarize the approaches from the perspective of haptic and pseudo-haptic cues that exhibit the sense of weight such as force, skin deformation, vibration, inertia, controlâdisplay ratio, velocity, body gestures, and audioâvisual representation. The design challenges are underlined, and research gaps are discussed, including accuracy and precision, weight discrimination, heavyweight rendering, and absolute weight simulation. This article is anticipated to aid in the development of more realistic weight perception in VR and stimulated new research interest in this topic
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