A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Pressure Feedback Display <s> BackgroundThe users of today's commercial prosthetic hands are not given any conscious sensory feedback. To overcome this deficiency in prosthetic hands we have recently proposed a sensory feedback system utilising a "tactile display" on the remaining amputation residual limb acting as man-machine interface. Our system uses the recorded pressure in a hand prosthesis and feeds back this pressure onto the forearm skin. Here we describe the design and technical solution of the sensory feedback system aimed at hand prostheses for trans-radial/humeral amputees. Critical parameters for the sensory feedback system were investigated.MethodsA sensory feedback system consisting of five actuators, control electronics and a test application running on a computer has been designed and built. Firstly, we investigate which force levels were applied to the forearm skin of the user while operating the sensory feedback system. Secondly, we study if the proposed system could be used together with a myoelectric control system. The displacement of the skin caused by the sensory feedback system would generate artefacts in the recorded myoelectric signals. Accordingly, EMG recordings were performed and an analysis of the these are included. The sensory feedback system was also preliminarily evaluated in a laboratory setting on two healthy non-amputated test subjects with a computer generating the stimuli, with regards to spatial resolution and force discrimination.ResultsWe showed that the sensory feedback system generated approximately proportional force to the angle of control. The system can be used together with a myoelectric system as the artefacts, generated by the actuators, were easily removed using a simple filter. Furthermore, the application of the system on two test subjects showed that they were able to discriminate tactile sensation with regards to spatial resolution and level of force.ConclusionsThe results of these initial experiments in non-amputees indicate that the proposed tactile display, in its simple form, can be used to relocate tactile input from an artificial hand to the forearm and that the system can coexist with a myoelectric control systems. The proposed system may be a valuable addition to users of myoelectric prosthesis providing conscious sensory feedback during manipulation of objects. <s> BIB001 </s> A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Pressure Feedback Display <s> A complete glove-based master-slave tactile feedback system was developed to provide users with a remote sense of touch. The system features a force-sensing master glove with piezoresistive force sensors mounted at each finger tip, and a pressure-transmitting slave glove with silicone-based pneumatically controlled balloon actuators, mounted at each finger tip on another hand. A control system translates forces detected on the master glove, either worn by a user or mounted on a robotic hand, to discrete pressure levels at the fingers of another user. System tests demonstrated that users could accurately identify the correct finger and detect three simultaneous finger stimuli with 99.3% and 90.2% accuracy, respectively, when the subjects were located in separate rooms. The glove-based tactile feedback system may have application to virtual reality, rehabilitation, remote surgery, medical simulation, robotic assembly, and military robotics. <s> BIB002 </s> A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Pressure Feedback Display <s> PURPOSE ::: This study explores the possibilities of transferring peripheral tactile stimulations from an artificial hand to the forearm skin. ::: ::: ::: METHOD ::: A tactile display applied to the forearm skin was used to transfer tactile input to the forearm from various locations on a hand displayed on a computer screen. Discernment of location, levels of pressure and a combination of the two in simulated functional grips was tested to quantify the participants' ability to accurately perceive the tactile stimulations presented. Ten participants (5 forearm amputees and 5 able-bodied volunteers) unfamiliar with the equipment participated in the three-stage experiments comprising a learning session with vision, a reinforced learning session without vision and a validation session without vision. ::: ::: ::: RESULTS ::: The location discernment accuracy was high in both groups (75.2% and 89.6% respectively). The capacity to differentiate between three different levels of pressure was also high (91.7% and 98.1% respectively in the two groups). Recognition of simulated grip was slightly more difficult with the groups scoring 58.7% and 68.0% respectively for accuracy in the validation session. ::: ::: ::: CONCLUSIONS ::: This study demonstrates that it is possible, following a brief training period, to transfer tactile input from an artificial hand to the forearm skin. The level of accuracy was lower for the more complex task, simulated grip recognition, possibly because this represents a more complex task requiring higher order brain functions. These results could form the basis for developing sensory feedback in hand prostheses. <s> BIB003 </s> A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Pressure Feedback Display <s> This paper proposes a haptic prosthetic hand to realize intuitive operation for upper limb amputees. In the conventional myoelectric prostheses, it was hardly unable to control the grasping force precisely or to grasp an unevenly shaped object flexibly. In this paper, development of haptic prosthetic hand is achieved, which realizes intuitive operation by the following two functions: first, is the transmission of force sensation to the master interface attached to the healthy part of the body, second, is an adaptation to the shape of an object with flexibleness. The developed haptic prosthetic hand has multi degrees of freedom (DOFs), and the master interface has a limited number of DOF. Therefore, to control the multi-DOFs haptic prosthetic hand by a simple operation of the master interface, different DOF bilateral control is implemented as a control method. Haptics is used to realize intuitive operation, and the proposed variable compliance control is used for environmental adaptation. These functions enable to replace the force sensation of the missing hand, by any remaining healthy part of the body. Experiments were conducted to evaluate the function of the developed haptic prosthetic hand. <s> BIB004 </s> A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses <s> Pressure Feedback Display <s> This study proposes a novel prosthetic hand that can artificially replace human sensation using haptic transplant technology. Conventional motorized prostheses are unable to precisely control the grasping force of the hand due to the lack of force sensation. In this paper, a haptic prosthetic hand is developed that allows for intuitive operation and precise force adjustment. These functions are realized by artificially transplanting the tactile sensation of a healthy part of the user's body to the amputated part of their body. The haptic transplant technology transmits the force sensation of the prosthesis to the master interface attached to the amputee's healthy part of body using bilateral control without a force sensor. Furthermore, variable compliance control is proposed for flexible adaptation to the shape of the object being grasped. The effectiveness of the proposed system was experimentally verified by comparing the controllability of the proposed system with that of a myoelectric prosthesis. In summary, an artificial replacement for human sensation was developed, and the intuitive operability and flexibility of the proposed system were confirmed. <s> BIB005
The pressure feedback display usually deals with conveying the tactile information to the user's brain by mean of pressing or vertically deforming the skin of the residual part BIB001 . Table 1 summarizes the works on the pressure feedback  display. A pressure wearable device was designed and installed on the forearm of fully able-body volunteers, to enhance the performance of the myoelectric prosthetic hand and recover the sensation of touch to its user BIB001 . The 15 mm plastic levers with 12 mm circular diameter plastic buttons powered by five digital servomotors (Graupner DS281, Germany) were used to apply pressure on the patient's skin, which was proportional to the amount of the measured contact pressure, as shown in Fig. 4 . The same technique has been used in another study BIB003 to discernment the preferable location and the pressure level of the pressure feedback display, in order to deliver the grasping contact pressure to the user of the upper limb prostheses with high performance and an approval rating of recognition accuracy. Five of the silicone-based balloon actuators (Marsh Bellofram T3210 type) were fixed on the fingertip of the two subjects that engaged in the study BIB002 . Five pressure actuators were used to excite the skin of the volunteers' fingertips by applying air pressure to deform the skin, which was related to the sensing signal provided from the sensor system. The generated pressure due to the connection force between the object and the prosthetic's fingers can be measured and directly translated to a pressure feedback stimulation by displacement of the patient's skin. The results found that subjects were able to discriminate the contact pressure in one finger and in three fingers at the same time with 99.3% and 90.2% identification accuracy, respectively. On the other hand, the pressure feedback display was used to estimate the shape of the grasping objects by utilizing a multi-degree of freedom prosthetic hand BIB004 BIB005 . Subsequently, the estimated signals were transmitted by mean of Bilateral control to a single 3D printed pressing interfacing device to excite the thumb finger of the patient's foot. The authors found that the suggested haptic system is easier to operate than the classical systems without any training period. However, they recommended to follow a programmable training to improve using the haptic prosthetic hand in daily life. 