Design, characterisation and validation of a haptic interface based on twisted string actuation.

This paper presents the design and experimental characterisation of a wrist haptic interface based on a twisted string actuator. The interface is designed for controlled actuation of wrist flexion/extension and is capable of rendering torque feedback through a rotary handle driven by the twisted string actuator and spring-loaded cable mechanisms. The interface was characterised to obtain its static and dynamic haptic feedback rendering capabilities. Compliance in the spring and actuation mechanism makes the interface suitable for smooth rendering of haptic feedback of large magnitudes due to the high motion transmission ratio of the twisted strings. Haptic virtual wall rendering capabilities are demonstrated

Towards a self-collision aware teleoperation framework for compound robots

This work lays the foundations of a self-collision aware teleoperation framework for compound robots. The need of an haptic enabled system which guarantees self-collision and joint limits avoidance for complex robots is the main motivation behind this paper. The objective of the proposed system is to constrain the user to teleoperate a slave robot inside its safe workspace region through the application of force cues on the master side of the bilateral teleoperation system. A series of simulated experiments have been performed on the Kuka KMRiiwa mobile robot; however, due to its generality, the framework is prone to be easily extended to other robots. The experiments have shown the applicability of the proposed approach to ordinary teleoperation systems without altering their stability properties. The benefits introduced by this framework enable the user to safely teleoperate whichever complex robotic system without worrying about self-collision and joint limitations

A Novel Untethered Hand Wearable with Fine-Grained Cutaneous Haptic Feedback

During open surgery, a surgeon relies not only on the detailed view of the organ being operated upon and on being able to feel the fine details of this organ but also heavily relies on the combination of these two senses. In laparoscopic surgery, haptic feedback provides surgeons information on interaction forces between instrument and tissue. There have been many studies to mimic the haptic feedback in laparoscopic-related telerobotics studies to date. However, cutaneous feedback is mostly restricted or limited in haptic feedback-based minimally invasive studies. We argue that fine-grained information is needed in laparoscopic surgeries to study the details of the instrument’s end and can convey via cutaneous feedback. We propose an exoskeleton haptic hand wearable which consists of five 4 ⇥ 4 miniaturized fingertip actuators, 80 in total, to convey cutaneous feedback. The wearable is described as modular, lightweight, Bluetooth, and WiFi-enabled, and has a maximum power consumption of 830 mW. Software is developed to demonstrate rapid tactile actuation of edges; this allows the user to feel the contours in cutaneous feedback. Moreover, to demonstrate the idea as an object displayed on a flat monitor, initial tests were carried out in 2D. In the second phase, the wearable exoskeleton glove is then further developed to feel 3D virtual objects by using a virtual reality (VR) headset demonstrated by a VR environment. Two-dimensional and 3D objects were tested by our novel untethered haptic hand wearable. Our results show that untethered humans understand actuation in cutaneous feedback just in a single tapping with 92.22% accuracy. Our wearable has an average latency of 46.5 ms, which is much less than the 600 ms tolerable delay acceptable by a surgeon in teleoperation. Therefore, we suggest our untethered hand wearable to enhance multimodal perception in minimally invasive surgeries to naturally feel the immediate environments of the instruments

Exodex Adam—A Reconfigurable Dexterous Haptic User Interface for the Whole Hand

Applications for dexterous robot teleoperation and immersive virtual reality are growing. Haptic user input devices need to allow the user to intuitively command and seamlessly “feel” the environment they work in, whether virtual or a remote site through an avatar. We introduce the DLR Exodex Adam, a reconfigurable, dexterous, whole-hand haptic input device. The device comprises multiple modular, three degrees of freedom (3-DOF) robotic fingers, whose placement on the device can be adjusted to optimize manipulability for different user hand sizes. Additionally, the device is mounted on a 7-DOF robot arm to increase the user’s workspace. Exodex Adam uses a front-facing interface, with robotic fingers coupled to two of the user’s fingertips, the thumb, and two points on the palm. Including the palm, as opposed to only the fingertips as is common in existing devices, enables accurate tracking of the whole hand without additional sensors such as a data glove or motion capture. By providing “whole-hand” interaction with omnidirectional force-feedback at the attachment points, we enable the user to experience the environment with the complete hand instead of only the fingertips, thus realizing deeper immersion. Interaction using Exodex Adam can range from palpation of objects and surfaces to manipulation using both power and precision grasps, all while receiving haptic feedback. This article details the concept and design of the Exodex Adam, as well as use cases where it is deployed with different command modalities. These include mixed-media interaction in a virtual environment, gesture-based telemanipulation, and robotic hand–arm teleoperation using adaptive model-mediated teleoperation. Finally, we share the insights gained during our development process and use case deployments

A Universal Volumetric Haptic Actuation Platform

In this paper, we report a method of implementing a universal volumetric haptic actuation platform which can be adapted to fit a wide variety of visual displays with flat surfaces. This platform aims to enable the simulation of the 3D features of input interfaces. This goal is achieved using four readily available stepper motors in a diagonal cross configuration with which we can quickly change the position of a surface in a manner that can render these volumetric features. In our research, we use a Microsoft Surface Go tablet placed on the haptic enhancement actuation platform to replicate the exploratory features of virtual keyboard keycaps displayed on the touchscreen. We ask seven participants to explore the surface of a virtual keypad comprised of 12 keycaps. As a second task, random key positions are announced one at a time, which the participant is expected to locate. These experiments are used to understand how and with what fidelity the volumetric feedback could improve performance (detection time, track length, and error rate) of detecting the specific keycaps location with haptic feedback and in the absence of visual feedback. Participants complete the tasks with great success (p < 0.05). In addition, their ability to feel convex keycaps is confirmed within the subjective comments.Peer reviewe

Social Touch

Interpersonal or social touch is an intuitive and powerful way to express and communicate emotions, comfort a friend, bond with teammates, comfort a child in pain, and soothe someone who is stressed. If there is one thing that the current pandemic is showing us, it is that social distancing can make some people crave physical interaction through social touch. The notion of “skin-hunger” has become tangible for many.Social touch differs at a functional and anatomical level from discriminative touch, and has clear effects at physiological, emotional, and behavioural levels. Social touch is a topic in psychology (perception, emotion, behaviour), neuroscience (neurophysiological pathways), computer science (mediated touch communication), engineering (haptic devices), robotics (social robots that can touch), humanities (science and technology studies), and sociology (the social implications of touch). Our current scientific knowledge of social touch is scattered across disciplines and not yet adequate for the purpose of meeting today's challenges of connecting human beings through the mediating channel of technology

A Virtual Reality Application of the Rubber Hand Illusion Induced by Ultrasonic Mid-Air Haptic Stimulation

Ultrasonic mid-air haptic technologies, which provide haptic feedback through airwaves produced using ultrasound, could be employed to investigate the sense of body ownership and immersion in virtual reality (VR) by inducing the virtual hand illusion (VHI). Ultrasonic mid-air haptic perception has solely been investigated for glabrous (hairless) skin, which has higher tactile sensitivity than hairy skin. In contrast, the VHI paradigm typically targets hairy skin without comparisons to glabrous skin. The aim of this article was to investigate illusory body ownership, the applicability of ultrasonic mid-air haptics, and perceived immersion in VR using the VHI. Fifty participants viewed a virtual hand being stroked by a feather synchronously and asynchronously with the ultrasonic stimulation applied to the glabrous skin on the palmar surface and the hairy skin on the dorsal surface of their hands. Questionnaire responses revealed that synchronous stimulation induced a stronger VHI than asynchronous stimulation. In synchronous conditions, the VHI was stronger for palmar stimulation than dorsal stimulation. The ultrasonic stimulation was also perceived as more intense on the palmar surface compared to the dorsal surface. Perceived immersion was not related to illusory body ownership per se but was enhanced by the provision of synchronous stimulation

Challenges of controlling the rotation of virtual objects with variable grip using force-feedback gloves

Some virtual reality (VR) applications require true-to-life object manipulation, such as for training or teleoperation. We investigate an interaction technique that replicates the variable grip strength applied to a held object when using force-feedback gloves in VR. We map the exerted finger pressure to the rotational freedom of the virtual object. With a firm grip, the object’s orientation is fixed to the hand. With a loose grip, the user can allow the object to rotate freely within the hand. A user study (N = 21) showed how challenging it was for participants to control the object’s rotation with our prototype employing the SenseGlove DK1. Despite high action fidelity, the grip variability led to poorer performance and increased task load compared to the default fixed rotation. We suspect low haptic fidelity as an explanation as only kinesthetic forces but no cutaneous cues are rendered. We discuss the system design limitations and how to overcome them in future haptic interfaces for physics-based multi-finger object manipulation

Haptic Interfaces for Virtual Reality: Challenges and Research Directions

The sense of touch (haptics) has been applied in several areas such as tele-haptics, telemedicine, training, education, and entertainment. As of today, haptics is used and explored by researchers in many more multi-disciplinary and inter-disciplinary areas. The utilization of haptics is also enhanced with other forms of media such as audio, video, and even sense of smell. For example, the use of haptics is prevalent in virtual reality environments to increase the immersive experience for users. However, while there has been significant progress within haptic interfaces throughout the years, there are still many challenges that limit their development. This review highlights haptic interfaces for virtual reality ranging from wearables, handhelds, encountered-type devices, and props, to mid-air approaches. We discuss and summarize these approaches, along with interaction domains such as skin receptors, object properties, and force. This is in order to arrive at design challenges for each interface, along with existing research gaps