A hybrid haptic stimulation prosthetic wearable device to recover the missing sensation of the upper limb amputees

A hybrid haptic feedback stimulation system that is capable in sensing the contact pressure, the surface texture, and the temperature, simultaneously, was designed for a prosthetic hand to provide a tactile sensation to amputation patients. In addition, the haptic system was developed to enable the prosthetic’s users to implement withdrawal reflexes due to the thermal noxious stimulus in a quick manner. The re-sensation is achieved by non-invasively stimulating the skin of the patients’ residual limbs, based on the type and the level of tactile signals provided by the sensory system of the prostheses. Accordingly, three stages of design and development were performed to satisfy the research methodology. A vibrotactile prosthetic device, which is designed for the detection of contact pressure and surface texture in upper extremity, represents. While, the design of a novel wearable hybrid pressure-vibration haptic feedback stimulation device for conveying the tactile information regarding the contact pressure between the prosthetic hand and the grasped objects represents the second methodology stage. Lastly, the third stage was achieved by designing a novel hybrid pressure-vibration-temperature feedback stimulation system to provide a huge information regarding the prostheses environment to the users without brain confusing or requiring long pre-training. The main contribution of this work is the development and evaluation of the first step of a novel approach for a lightweight, 7 Degrees-Of-Freedom (DOF) tactile prosthetic arm to perform an effective as well as fast object manipulation and grasping. Furthermore, this study investigates the ability to convey the tactile information about the contact pressure, surface texture, and object temperature to the amputees with high identification accuracy by mean of using the designed hybrid pressure-vibration-temperature feedback wearable device. An evaluation of sensation and response has been conducted on forty healthy volunteers to evaluate the ability of the haptic system to stimulate the human nervous system. The results in term of Stimulus Identification Rate (SIR) show that all the volunteers were correctly able to discriminate the sensation of touch, start of touch, end of touch, and grasping objects. While 94%, 96%, 97%, and 95.24% of the entire stimuli were successfully identified by the volunteers during the experiments of slippage, pressure level, surface texture, and temperature, respectively. The position tracking controller system was designed to synchronize the movements of the volunteers’ elbow joints and the prosthetic’s elbow joint to record the withdrawal reflexes. The results verified the ability of the haptic system to excite the human brain at the abnormal noxious stimulus and enable the volunteers to perform a quick withdrawal reflex within 0.32 sec. The test results and the volunteers' response established evidence that amputees are able to recover their sense of the contact pressure, the surface texture, and the object temperature as well as to perform thermal withdrawal reflexes using the solution developed in this work

Slip Prediction for Upper-Limb Prosthetics

Amputees have greatly benefitted from improved prosthetic technologies, increasing dexterity, degrees of freedom, and attachment to the body, however sensory feedback has made comparatively little improvement. Osseointegration has been shown to produce a transcutaneous pathway to allow for long term stable invasive electrical stimulation [1], [2]. The need for useful prosthetic feedback has been pre-existing, however now there is the capability for prosthetics to begin recreating lost sensations through neural stimulation. This thesis investigates the ability to create a slip prediction system, in a currently existing and widely used commercially available prosthetic hand. This slip prediction system is designed to alert the user before slip begins to occur to maximize potential usefulness. Two methods of stimulation are compared to a no-stimulation baseline in execution of a task designed to induce slip. Improvements are indicated through a reduction in number of slips, and improved understanding of grip capabilities, shown by prosthetic movement planning within grasp limits. One stimulation condition delivers a single rapid stimulation “spike” as slip becomes more likely. The other stimulation condition delivers a continuous stimulation, with amplitude proportional to slip likelihood. The predictor is shown to have a prediction accuracy of 69% when used with feedback. Slips across all four participants were shown to be reduced by stimulation, as 53 slips occurred using no stim, 37 slips occurred using the spike feedback, and 31 slips occurred using the amplitude feedback; however this decrease was not shown to be statistically significant. This indicates that the neural stimulation slip prediction delivered in this thesis, provided additional and actionable information even when the participant could see, hear, and freely move the prosthesis