A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Skin Stretch Feedback Display <s> We describe a wearable haptic feedback device that imparts rotational skin stretch to provide feedback regarding movement of a virtual object. Applications for this device include feedback of motion for physical therapy or rehabilitation exercises or proprioceptive feedback for amputees. The device uses a small piezoelectric motor for a combination of low weight, moderate torques and rotation without vibrations that could interfere with the sensation of stretch. We present the results of experiments to determine the accuracy with which subjects can use feedback from the device to control the orientation of a virtual object. Most subjects were able to position the device within several degrees. In a second test, subjects were asked to identify randomly applied levels of skin stretch while they remained passive. In this case, the accuracy was poorer and subjects occasionally confused positive and negative rotations. Tests were also conducted to evaluate the effect of rotational compliance at the end effector, added to improve comfort at large displacements. <s> BIB001 </s> A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Skin Stretch Feedback Display <s> We present a wearable haptic feedback device that imparts rotational skin stretch to the hairy skin, along with the results of psychophysical tests to determine its resolution and accuracy for motion display. Tracking experiments with visual markers reveal the pattern of skin motion and strain imparted by the device, confirming subjective impressions that the design represents a trade-off between perception at low stimulus levels and comfort at maximum stimulus levels. In an isolated environment, users were able to discriminate between different rotational displacements of stretch within two to five degrees, depending on the reference stimulus. In a more realistic setting, subjects were able to use feedback from the device to control the positioning of a virtual object within six degrees or ±6.5 degrees of the total range of motion. When subjects were passive and exposed to arbitrary rotations of the device, the accuracy was poorer, although it improved with training. The results suggest that wearable skin stretch devices can be an effective means of providing feedback about a user's controlled joint or limb motions for motion training and similar applications. <s> BIB002 </s> A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Skin Stretch Feedback Display <s> We present a new wearable haptic device that provides a sense of position and motion by inducing rotational skin stretch on the user's skin. In the experiments described in this paper, the device was used to provide proprioceptive feedback from a virtual prosthetic arm controlled with myoelectric sensors on the bicep and tricep muscles in 15 able-bodied participants. Targeting errors in blind movements with the haptic device were compared to cases where no feedback and contralateral proprioception were provided. Average errors were lower with the device than with no feedback but larger than with contralateral proprioceptive feedback. Participants also had lower visual demand with the device than with no feedback while tracking a 30 ( degrees ) moving range. The results indicate that the rotational skin stretch may ultimately be effective for proprioceptive feedback in myoelectric prostheses, particularly when vision is otherwise occupied. <s> BIB003 </s> A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Skin Stretch Feedback Display <s> This paper presents a novel cutaneous device capable of providing independent skin stretches at the palmar, dorsal, ulnar, and radial sides of the arm. It consists of a lightweight bracelet with four servo motors. Each motor actuates a cylindrical shaped end-effector that is able to rotate, generating skin stretch stimuli. To understand how to control and wear the device on the forearm to evoke the most effective cutaneous sensations, we carried out perceptual experiments evaluating its absolute and differential thresholds. Finally, we carried out an experiment of haptic navigation to assess the effectiveness of our device as a navigation feedback system to guide a desired rotation and translation of the forearm. Results demonstrate an average rotation and translation error of 1.87° and 2.84 mm, respectively. Moreover, all the subjects found our device easy to wear and comfortable. Nine out of ten found it effective in transmitting navigation information to the forearm. <s> BIB004 </s> A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Skin Stretch Feedback Display <s> Myoelectric prostheses have seen increased application in clinical practice and research, due to their potential for good functionality and versatility. Yet, myoelectric prostheses still suffer from a lack of intuitive control and haptic feedback, which can frustrate users and lead to abandonment. To address this problem, we propose to convey proprioceptive information for a prosthetic hand with skin stretch using the Rice Haptic Rocker. This device was integrated with the myo-controlled version of Pisa/IIT SoftHand and a size discrimination test with 18 able bodied subjects was performed to evaluate the effectiveness of the proposed approach. Results show that the Rice Haptic Rocker can be successfully used to convey proprioceptive information. A Likert survey was also presented to the experiment participants, who evaluated the integrated setup as easy to use and effective in conveying proprioception. <s> BIB005 </s> A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Skin Stretch Feedback Display <s> This paper presents a novel sensory feedback device and an original method aiming to provide skin stretch feedback of three degree-of-freedom wrist movements, which are extension-flexion, radial-ulnar deviation and pronation-supination, to prosthetic hand users. In order to evaluate the performance of the device, a test setup is built. A user study with able-bodied participants is conducted. Confusion matrices are created from the experimental data, and the results are analyzed in terms of correct identification of the intended stimulations. Analysis shows that the proposed design together with the sensory feedback method is a viable option for proprioceptive feedback lacking in robotic prosthetic hands. <s> BIB006 </s> A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Skin Stretch Feedback Display <s> We present a wearable skin stretch device for the forearm. It is composed of four cylindrical end effectors, evenly distributed around the user's forearm. They can generate independent skin stretch stimuli at the palmar, dorsal, ulnar, and radial sides of the arm. When the four end effectors rotate in the same direction, the wearable device provides cutaneous stimuli about a desired pronation/supination of the forearm. On the other hand, when two opposite end effectors rotate in different directions, the cutaneous device provides cutaneous stimuli about a desired translation of the forearm. To evaluate the effectiveness of our device in providing navigation information, we carried out two experiments of haptic navigation. In the first one, subjects were asked to translate and rotate the forearm toward a target position and orientation, respectively. In the second experiment, subjects were asked to control a 6-DoF robotic manipulator to grasp and lift a target object. Haptic feedback provided by our wearable device improved the performance of both experiments with respect to providing no haptic feedback. Moreover, it showed similar performance with respect to sensory substitution via visual feedback, without overloading the visual channel. <s> BIB007 </s> A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Skin Stretch Feedback Display <s> Skin stretch haptic devices are well-suited for transmitting information through touch, a promising avenue in prosthetic research, addressing the lack of feedback in myoelectric designs. Rocker-based skin stretch devices have been proposed for sensory substitution and navigational feedback, but the designs vary in their geometry. Other works create torsional stretch, and utilize nonlinear mappings to enhance perception. This work investigates parameters of rocker geometry and mapping functions, and how they impact user perception. We hypothesize that perceptual changes are dependent on the choice of stretch increment sizes over the range of motion. The rocker geometry is varied with an offset between the rotational and geometric axes, and three rocker designs are evaluated during a targeting task implemented with a nonlinear or linear mapping. The rockers with no offset and a positive offset (wide) perform better than the negative offset (narrow) case, though the mapping method does not affect target accuracy. <s> BIB008 </s> A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Skin Stretch Feedback Display <s> Objective: Myoelectric hand prostheses have reached a considerable technological level and gained an increasing attention in assistive robotics. However, their abandonment rate remains high, with unintuitive control and lack of sensory feedback being major causes. Among the different types of sensory information, proprioception, e.g., information on hand aperture, is crucial to successfully perform everyday actions. Despite the many attempts in literature to restore and convey this type of feedback, much remains to be done to close the action-perception loop in prosthetic devices. Methods: With this as motivation, in this paper we introduce HapPro, a wearable, noninvasive haptic device that can convey proprioceptive information for a prosthetic hand. The device was used with an under-actuated, simple to control anthropomorphic robotic hand, providing information about hand aperture by mapping it to the position of a wheel that can run on the user's forearm. Tests with 43 able bodied subjects and one amputee subject were conducted in order to quantify the effectiveness of HapPro as a feedback device. Results: HapPro provided a good level of accuracy for item discrimination. Participants also reported the device to be intuitive and effective in conveying proprioceptive cues. Similar results were obtained in the proof-of-concept experiment with an amputee subject. Conclusions: Results show that HapPro is able to convey information on the opening of a prosthetic hand in a noninvasive way. Significance: Using this device for proprioceptive feedback could improve usability of myoelectric prostheses, potentially reducing abandonment and increasing quality of life for their users. <s> BIB009
The skin stretch feedback display is another mechanism of local skin deformation, depends on scratching the skin to provide the tactile data to amputees with the haptic upper limb prostheses BIB006 . A brief summary of the previous works that investigated how to use the skin stretch feedback display to excite the skin of the haptic prostheses users was listed in Table 3 . A haptic skin stretch wearable device, called Haptic Rocker, has been designed to convey useful information of the size of the grasped objects in BIB005 . The haptic device was mounted on the patient's upper arm. It consists of a frame, strap, rocker, and servomotor, as described in Fig. 6 . A. The wearable device was integrated with 19 DoFs Pisa/IIT SoftHand to perform the experimental functionality tests. The results showed that the skin stretch haptic system was able to recognize the objects' shapes successfully, with an average accuracy of 73.3 ± 11.2%. In a similar study, HapPro wearable device of 75 g total weight was designed BIB009 . The main idea of the haptic device is to enable a cart to slide linearly over the skin of the forearm, in order to convey the sensation of the objects' size to the user of the prosthetic hand, as shown in Fig. 6 . B. A DC motor (Pololu 298:1 Micro Metal Gearmotor) was employed as the mechanical power source, in which the rotational movement can be transformed to a linear movement by mean of pulley system. The experimental tests on 43 healthy participants and one amputee subject confirmed that the HapPro wearable device is an effective device for exciting the patients' brain. B) The HapPro wearable device BIB009 . On the other hand, a new skin stretch mechanoreceptors wearable device has been designed to discriminate the position and motion of the upper limb prostheses through sensing the rotational stretch on the skin of the upper residual arm BIB001 BIB002 BIB003 . The device was designed from two 14mm circular end effector driven by an ultrasonic piezoelectric motor (Shinsei Motor, USR30-B3). The end effectors were able to excite the skin with 0.6 N.m effecting torque. The evaluation experiments on able-bodied subjects indicated that, the device has significant benefit for recovery the sensation when integrated with the myoelectric prosthetic hand. However, few hours of training were highly recommended. Other haptic skin stretch techniques were presented in BIB004 BIB007 BIB008 . The wearable device was designed with four independent cylindrical end effectors driven by four servo motors. The lightweight device was installed on the subjects' forearm to allow the end effectors stretch the skin at the palmar, dorsal, ulnar, and radial sides of the arm. The main aim of such wearable devices is to navigate the robotic arms by controlling the position and the orientation of the robotics' end effectors with a complete absence of any visual information. 