A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Fig. 5-A) Vibration motors on the forearm. B) The stimulation response during holding the empty bottle. <s> Upper-limb prostheses users lack proprioception of their artificial arm, and rely heavily on vision to understand its configuration. With the goal of reducing the amount of energy expended on visual cues during upper-limb prosthesis use, this study investigates whether haptic feedback can relay the configuration of a virtual hand in the absence of sight. Two mappings from waistbelt-mounted tactor vibration patterns to hand configuration are explored: (1) Synergy-based hand motions derived from the results of a principal component analysis run on an aggregate of hand motions and (2) Decoupled hand motions, which include experimenter-selected motions such as finger grasp and finger spread. Results show that users can identify complex hand configurations with vibrotactile feedback patterns based on both the Synergies and Decoupled methods, although 30–45 seconds are required to achieve this task. Also, findings demonstrate that users are likely to memorize correspondence between an overall feeling of the tactor pattern to a hand configuration rather than constructing the hand configuration by isolating and considering each tactor individually. Last, results indicate that hand configuration is most accurately conveyed by maximizing information along a synergy-based space. <s> BIB001 </s> A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Fig. 5-A) Vibration motors on the forearm. B) The stimulation response during holding the empty bottle. <s> Recent advances in myoelectric prosthetic technology have enabled more complex movements and interactions with objects, but the lack of natural haptic feedback makes object manipulation difficult to perform. Our research effort aims to develop haptic feedback systems for improving user performance in object manipulation. Specifically, in this work, we explore the effectiveness of vibratory tactile feedback of slip information for grasping objects without slipping. A user interacts with a virtual environment to complete a virtual grasp and hold task using a Sensable Phantom. Force feedback simulates contact with objects, and vibratory tactile feedback alerts the user when a virtual object is slipping from the grasp. Using this task, we found that tactile feedback significantly improved a user’s ability to detect and respond to slip and to recover the slipping object when visual feedback was not available. This advantage of tactile feedback is especially important in conjunction with force feedback, which tends to reduce a subject’s grasping forces and therefore encourage more slips. Our results demonstrate the potential of slip feedback to improve a prosthesis user’s ability to interact with objects with less visual attention, aiding in performance of everyday manipulation tasks. <s> BIB002 </s> A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Fig. 5-A) Vibration motors on the forearm. B) The stimulation response during holding the empty bottle. <s> Tactile feedback is essential to intuitive control and to promote the sense of self-attribution of a prosthetic limb. Recent findings showed that amputees can be tricked to experience this embodiment, when synchronous and modality-matched stimuli are delivered to biological afferent structures and to an alien rubber hand. Hence, it was suggested to exploit this effect by coupling touch sensors in a prosthesis to an array of haptic tactile stimulators in the prosthetic socket. However, this approach is not clinically viable due to physical limits of current haptic devices. To address this issue we have proposed modality-mismatched stimulation and demonstrated that this promotes self-attribution of an alien hand on normally limbed subjects. In this work we investigated whether similar effects could be induced in transradial amputees with referred phantom sensations in a series of experiments fashioned after the Rubber Hand Illusion using vibrotactile stimulators. Results from three independent measures of embodiment demonstrated that vibrotactile sensory substitution elicits body-ownership of a rubber hand in transradial amputees. These results open up promising possibilities in this field; indeed miniature, safe and inexpensive vibrators could be fitted into commercially available prostheses and sockets to induce the illusion every time the prosthesis manipulates an object. <s> BIB003 </s> A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Fig. 5-A) Vibration motors on the forearm. B) The stimulation response during holding the empty bottle. <s> Abstract Human rely profoundly on tactile feedback from fingertips to interact with the environment, whereas most hand prostheses used in clinics provide no tactile feedback. In this study we demonstrate the feasibility to use a tactile display glove that can be worn by a unilateral hand amputee on the remaining healthy hand to display tactile feedback from a hand prosthesis. The main benefit is that users could easily distinguish the feedback for each finger, even without training. The claimed advantage is supported by preliminary tests with healthy subjects. This approach may lead to the development of effective and affordable tactile display devices that provide tactile feedback for individual fingertip of hand prostheses. <s> BIB004 </s> A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Fig. 5-A) Vibration motors on the forearm. B) The stimulation response during holding the empty bottle. <s> This paper presents a vibrotactile haptic feedback system for use under dynamic conditions, verifies its functionality, and shows how results may be affected by the amount of training that subjects receive. We hope that by using vibrotactile feedback to distinguish between different textures, upper-limb amputees may be able to partially regain the sense of touch. During a previous experiment (Motamedi et al., 2015) we noticed a correlation between how familiar the subjects were with haptic systems, and how well they were able to use the haptic system to accurately identify textures. This observation lead us to conduct a second experiment, the results of which are the main focus of this paper. We began with a group of subjects who were completely unfamiliar with haptic systems, and tracked the improvements in their accuracy over a period of four weeks. Although the subjects showed a 16% improvement in their ability to recognize textures, going from a 64% success rate after the first week to 80% after the fourth, perfect accuracy was not attained. A subsequent experiment, however, shows that this result should not diminish our perception of the haptic system's effectiveness. When we asked the same subjects to identify the textures using only their fingertips, we found that even humans cannot distinguish between near-identical textures with complete accuracy. The subjects' overall success rate when using their own hands was 91%, demonstrating that the proposed haptic system is not far from achieving the same texture recognition capabilities as the human sense of touch. <s> BIB005
It is worth mentioning that the location of installing the vibration feedback stimulators is completely depended on the amputation levels of the patients. Indeed, it depends completely on the mutilation level of the upper limb amputees and the nerves state of their residual parts. Therefore, previous research investigated several locations of the haptic vibrotactile system. The C2 vibrotactile stimulator (Engineering Acoustics, Inc., Casselberry, FL) has been installed on the upper arm of 23 healthy volunteers, in order to help the users of the upper limb prostheses to detect the slippage and prevent slipping object before dropping it in high response and acceptable accuracy BIB002 . Vibrotactile stimulation is capable to provide amputees with the extraordinary sensing of embodiment in their prosthetic when installing at the forearm of the patients BIB003 . On the other hand, five spot vibration feedback actuators are distributed over the fingers of healthy hand, with one motor for each finger, in order to detect the level of the contact pressure that was created by a virtual sensory system BIB004 . The C2 tactors are very effective to convey the tactile information to the subjects' brain when using as a haptic wearable belt fixed around the amputees' waist BIB001 . Finally, the effect of training to increase the recognition to the tactile feedback information of different surfaces texture when the vibrotactile stimulator installed on the neck was investigated BIB005 . It is found that the ability of the volunteers to correctly detect the texture of different surfaces was increased by 16% after four weeks of training. 