IEEE Transactions on Haptics

In this study, we were interested in the question whether vibrotactile thresholds on the back, in terms of the Just Noticeable Difference (JND), scale with back length. Although there exists only indirect physiological evidence, it could be assumed that the density of mechanoreceptors is lower if back size is larger. As a consequence, the JND would increase with back length. We measured psychophysical curves for 40 male participants with back lengths in the range of 36 to 55 cm. Nine equally spaced vibration motors were placed in vertical direction on their back, 2 cm left of the spine...

We investigated the enhancement of the perceived force strength in force feedback devices by combining the pulling illusion with kinesthetic illusions. The pulling illusion (i.e., a sensation of being pulled or pushed) is induced by asymmetric vibrations applied to the fingertips, enabling the implementation of small, lightweight, and ungrounded force feedback devices. However, the perceived force intensity is limited. We focused on the kinesthetic illusion, a phenomenon in which the movement of a limb in the direction of muscle extension is illusively perceived by presenting vibrations to tendons or muscles as an illusion that could enhance the perceived strength of the pulling illusion...

Learning from demonstration is a proven technique to teach robots new skills. Data quality and quantity play a critical role in the performance of models trained using data collected from human demonstrations. In this paper we enhance an existing teleoperation data collection system with real-time haptic feedback to the human demonstrators; we observe improvements in the collected data throughput and in the performance of autonomous policies using models trained with the data. Our experimental testbed was a mobile manipulator robot that opened doors with latch handles...

Current Virtual Reality (VR) environments lack the haptic signals that humans experience during real-life interactions, such as the sensation of texture during lateral movement on a surface. Adding realistic haptic textures to VR environments requires a model that generalizes to variations of a user's interaction and to the wide variety of existing textures in the world. Current methodologies for haptic texture rendering exist, but they usually develop one model per texture, resulting in low scalability. We present a deep learning-based action-conditional model for haptic texture rendering and evaluate its perceptual performance in rendering realistic texture vibrations through a multi-part human user study...

Auditory and visual cues have been efficacious in laboratory-based freezing of gait (FoG) mitigation in Parkinson's disease (PD). However, real-life applications of these cues are restricted due to inconvenience to the users. Closed-loop vibrotactile cues based on temporal gait events have overcome the shortcomings of auditory and visual cueing. However, kinematic gait parameter-driven vibrotactile cueing has not been explored yet. Kinematic gait parameter-driven cueing is more effective than temporal cueing, according to FoG pathophysiology studies...

Haptic devices are becoming popular in many applications, including medical, gaming, and consumer devices. Yet, the majority of studies focus on the use of haptics for the upper limbs, with much less attention to the stimulation of other regions of the body such as the lower back. In this study, we designed three types of skin stretch stimulation devices that can be placed on a belt and apply tactile stimulation on the lower back. We present these devices that apply lateral, longitudinal, and rotational skin stretch stimulation on the lower back, and evaluate their effectiveness in providing haptic commands for the lower limbs of healthy participants...

This paper proposed linear and non-linear models for predicting human-exoskeleton coupling forces to enhance the studies of human-exoskeleton coupling dynamics. Then the parameters of these models were identified with a newly designed platform and the help of ten adult male and ten adult female volunteers (Age: 23.65 ±4.03 years, Height: 165.60 ±8.32 mm, Weight: 62.35 ±14.09 kg). Comparing the coupling force error predicted by the models with experimental measurements, one obtained a more accurate and robust prediction of the coupling forces with the non-linear model...

Rehabilitation robots have the potential to alleviate the global burden of neurorehabilitation. Robot-based multiplayer gaming with virtual and haptic interaction may improve motivation, engagement, and implicit learning in robotic therapy. Over the past few years, there has been growing interest in robot mediated haptic dyads, or human-robot-robot-human interaction. The effect of such a paradigm on motor learning in general and specifically for individuals with motor and/or cognitive impairments is an open area of research...

This paper outlines the design, characterization, and validation of a novel wearable haptic device capable of delivering skin stretch, force feedback, or a combination of both, to the user's arm. In this study, we conducted physical and perceptual characterization with eleven able-bodied participants, and two separate experiments involving discrimination and manipulation tasks, encompassing a total of 32 participants. In both experiments, we used the CUFF device in conjunction with the Pisa/IIT SoftHand. The first experiment was a discrimination task in which participants were required to differentiate between pairs of cylinders based on their dimensions and perceived softness...

A method of providing localised haptic feedback at precise locations on the body, utilising a lightweight textile garment is presented in this short paper. The textile comprises of subtly integrated actuator yarns (HaptiYarns) which are controlled by electropneumatic circuitry. Each yarn has two functional layers, an inner porous textile layer with limited extensibility and a second, durable outer layer made from an extensible elastomer. The HaptiYarns can provide radial forces and a maximum radial displacement of 28...

In this paper, we propose three methods to compute low-latency analog position where two of them fuse encoder and rate gyro signals. While one method is based on gyro with bias correction using encoder information, the other one is encoder-referenced combined with a resettable integrator to minimize the staircase form of encoder signals. Experiments on a one degree-of-freedom haptic simulation system have shown that a low-latency analog position with an accuracy over 98% compared to the sampled encoder signal can be obtained...

The past decade has witnessed the development of tactile sensors, which have been increasingly considered as an essential equipment in robotics, especially the dexterous manipulation and collaborative human-robot interactions. There are two major types of tactile sensors, i.e., the vision-based and taxel-based sensors. The latter is capable of achieving lower integration complexity with existing robotic systems, but unable to provide high-resolution (HR) tactile information as that of the vision-based counterpart due to the manufacturing limitations...

Noisy vibrotactile signals transmitted during tactile explorations of an object provide precious information on the nature of its surface. Understanding the link between signal properties and how they are interpreted by the tactile sensory system remains challenging. In this paper, we investigated human perception of broadband, stationary vibrations recorded during exploration of textures and reproduced using a vibrotactile actuator. Since intensity is a well-established perceptual attribute, we here focused on the relevance of the spectral content...

This paper explores the design and experimental validation of a three-degree-of-freedom variable inertia generator. An inertia generator is a handheld haptic device that renders a prescribed inertia. In the mechanism proposed in this paper, three-dimensional torque feedback is achieved by accelerating three pairs of flywheels mounted on orthogonal axes. While the primary objective of this work is to design an inertia generator, this study also includes developing other functionalities for the device that exploit its torque generation capabilities...

Electroactive textile (EAT) has the potential to apply pressure stimuli to the skin, e.g. in the form of a squeeze on the arm. To present a perceivable haptic sensation we need to know the perception threshold for such stimuli. We designed a set-up based on motorized ribbons around the arm with five different widths (range 3 - 49 mm) for psychophysical studies. We investigated the perception threshold of force pressure and ribbon reduction in two studies, using two methods (PSI and 1up/3down staircase), comparing sex, the left and right arm, the lower and upper arm, and stimulated surface area with a total of 57 participants...

Pneumatic tactile displays dynamically customize surface morphological features with reconfigurable arrays of independently addressable actuators. However, their ability to render detailed tactile patterns or fine textures is limited by the low spatial resolution. For pneumatic tactile displays, the high-density integration of pneumatic actuators within a small space (fingertip) poses a significant challenge in terms of pneumatic circuit wiring. In contrast to the structure with a single-layer layout of pipes, we propose a multi-layered stacked microfluidic pipe structure that allows for a higher density of actuators and retains their independent actuation capabilities...

Haptic feedback is a method to provide tactile guidance in scenarios requiring multiple senses and divided attention like aviation. Earlier tests on a flight simulator and an in-flight test using the proposed tactile guidance method have shown the need to study its learning process. In this study, twelve participants completed two tactile guidance tasks without visual feedback across twelve sessions to analyze the learning effect. The paper shows an improvement between sessions in guidance accuracy, response time, and self-assessed workload...

Virtual exhibits with haptic feedback offer greater flexibility in diversifying content and providing digital affordance, even at a lower cost, than physical exhibits. However, few studies addressed the value of such haptics-enabled educational systems in informal learning environments. In this study, we investigated the feasibility of a haptic exhibit as an alternative or supplement for a traditional physical exhibit in a science museum. We developed a two-degree-of-freedom cable-driven haptic device to simulate physical interactions on a large visual display...

For human sensory processing, cluttered real-world environments where signals from multiple objects or events overlap are challenging. A cognitive function useful in such situations is an attentional selection of one signal from others based on the difference in bound feature. For instance, one can visually select a specific orientation if it is uniquely colored. However, here we show that unlike vision, touch is very poor at feature-based signal selection. We presented two-orthogonal line segments with different vibration textures to a fingertip...

Wearable haptic devices on the forearm can relay information from virtual agents, robots, and other humans while leaving the hands free. We introduce and test a new wearable haptic device that uses soft actuators to provide normal and shear force to the skin of the forearm. A rigid housing and gear motor are used to control the direction of the shear force. A 6-axis force/torque sensor, distance sensor, and pressure sensors are integrated to quantify how the soft tactor interacts with the skin. When worn by participants, the device delivered consistent shear forces of up to 0...