Assessment of intuitiveness and comfort of wearable haptic feedback strategies for assisting level and stair walking

Nowadays, lower-limb prostheses are reaching real-world usability especially on ground-level walking. However, some key tasks such as stair walking are still quite demanding. Providing haptic feedback about the foot placement on the steps might reduce the cognitive load of the task, compensating for increased dependency on vision and lessen the risk of falling. Experiments on intact subjects can be useful to define the feedback strategies prior to clinical trials, but effective methods to assess the efficacy of the strategies are few and usually rely on the emulation of the disability condition. The present study reports on the design and testing of a wearable haptic feedback system in a protocol involving intact subjects to assess candidate strategies to be adopted in clinical trials. The system integrated a sensorized insole wirelessly connected to a textile waist belt equipped with three vibrating motors. Three stimulation strategies for mapping the insole pressure data to vibrotactile feedback were implemented and compared in terms of intuitiveness and comfort perceived during level and stair walking. The strategies were ranked using a relative rating approach, which highlighted the differences between them and suggested guidelines for their improvement. The feedback evaluation procedure proposed could facilitate the selection and improvement of haptic feedback strategies prior to clinical testing

Cardio-respiratory monitoring in archery using a smart textile based on flexible fiber bragg grating sensors

In precision sports, the control of breathing and heart rate is crucial to help the body to remain stable in the shooting position. To improve stability, archers try to adopt similar breathing patterns and to have a low heartbeat during each shot. We proposed an easy-to-use and unobtrusive smart textile (ST) which is able to detect chest wall excursions due to breathing and heart beating. The sensing part is based on two FBGs housed into a soft polymer matrix to optimize the adherence to the chest wall and the system robustness. The ST was assessed on volunteers to figure out its performance in the estimation of respiratory frequency (fR) and heart rate (HR). Then, the system was tested on two archers during four shooting sessions. This is the first study to monitor cardio-respiratory activity on archers during shooting. The good performance of the ST is supported by the low mean absolute percentage error for fR and HR estimation (≤1.97% and ≤5.74%, respectively), calculated with respect to reference signals (flow sensor for fR, photopletismography sensor for HR). Moreover, results showed the capability of the ST to estimate fR and HR during different phases of shooting action. The promising results motivate future investigations to speculate about the influence of fR and HR on archers’ performance

Endoscopic Tactile Capsule for Non-Polypoid Colorectal Tumour Detection

An endoscopic tactile robotic capsule, embedding miniaturized MEMS force sensors, is presented. The capsule is conceived to provide automatic palpation of non-polypoid colorectal tumours during colonoscopy, since it is characterized by high degree of dysplasia, higher invasiveness and lower detection rates with respect to polyps. A first test was performed employing a silicone phantom that embedded inclusions with variable hardness and curvature. A hardness-based classification was implemented, demonstrating detection robustness to curvature variation. By comparing a set of supervised classification algorithms, a weighted 3-nearest neighbor classifier was selected. A bias force normalization model was introduced in order to make different acquisition sets consistent. Parameters of this model were chosen through a particle swarm optimization method. Additionally, an ex-vivo test was performed to assess the capsule detection performance when magnetically-driven along a colonic tissue. Lumps were identified as voltage peaks with a prominence depending on the total magnetic force applied to the capsule. Accuracy of 94 % in hardness classification was achieved, while a 100 % accuracy is obtained for the lump detection within a tolerance of 5 mm from the central path described by the capsule. In real application scenario, we foresee our device aiding physicians to detect tumorous tissues

A multi-parametric wearable system to monitor neck movements and respiratory frequency of computer workers

Musculoskeletal disorders are the most common form of occupational ill-health. Neck pain is one of the most prevalent musculoskeletal disorders experienced by computer workers. Wrong postural habits and non-compliance of the workstation to ergonomics guidelines are the leading causes of neck pain. These factors may also alter respiratory functions. Health and safety interventions can reduce neck pain and, more generally, the symptoms of musculoskeletal disorders and reduce the consequent economic burden. In this work, a multi-parametric wearable system based on two fiber Bragg grating sensors is proposed for monitoring neck movements and breathing activity of computer workers. The sensing elements were positioned on the neck, in the frontal and sagittal planes, to monitor: (i) flexion-extension and axial rotation repetitions, and (ii) respiratory frequency. In this pilot study, five volunteers were enrolled and performed five repetitions of both flexion-extension and axial rotation, and ten breaths of both quite breathing and tachypnea. Results showed the good performances of the proposed system in monitoring the aforementioned parameters when compared to optical reference systems. The wearable system is able to well-match the trend in time of the neck movements (both flexion-extension and axial rotation) and to estimate mean and breath-by-breath respiratory frequency values with percentage errors ≤6.09% and ≤1.90%, during quiet breathing and tachypnea, respectively

A Pneumatic Haptic Display for Collaborative Robotics applications

A pneumatic haptic display for collaborative robotics applications is presented within this paper. The 3x3 tactor array consists of a polymeric parallelepiped with 9 cylindrical chambers (3mm diameter) providing haptic feedback by means of pneumatic actuation. A preliminary study, on four subjects, has been performed to identify the optimal pressure to deliver the tactile stimulation and assess system functionality. Four different spatial stimuli, based on the activation of different chambers of the tactor array, were provided at three different pressure levels (35, 70, 105 kPa). Results suggest that a pressure of 70 kPa leads to a detection accuracy of 96.9% Further studies will focus on a deeper assessment of the tactile display using different configurations

[Intranuclear particles in chronic non-A, non-B hepatitis: what diagnostic significance?].

Intranuclear particles of 23-27 nm diameter have been repeatedly demonstrated in the nuclei of hepatocytes of patients with non-A, non-B hepatitis and of experimentally infected chimpanzees; however, their specificity has been challenged since they have also been observed in other pathological conditions and in healthy volunteers. We have conducted an ultrastructural study of liver biopsies from 10 patients with chronic active non-A, non-B hepatitis. The intranuclear particles, which were observed in all patients, were classified according to the aggregation patterns described by De Vos. Eight patients (80%) had particles of type 2. A reevaluation our proceeding data on Delta hepatitis demonstrated that no particles of type 2 were present. These results support the hypothesis that only type 2 particles are markers of non-A, non-B hepatitis

Soft large area FBG tactile sensors for exteroception and proprioception in a collaborative robotic manipulator

Interest in tactile sensing technologies is advancing due to the growing adoption of robots in daily life activities. Human-machine interaction has thus to be safe, and collaborative robotics is becoming increasingly important. The present work features the design, development and preliminary validation of a soft large area sensor for tactile and proprioceptive sensing in a collaborative robotic manipulator. Such a manipulator is shaped to resemble the human hand and within this paper we focused on the index finger. The finger architecture has a design which allows setting up a structured 3D model, with flexible parametrization and fast prototyping. An optical fiber embedding 12 Fiber Bragg Gratings (FBGs) has been integrated in a soft polymeric matrix to mimic human sense of touch abilities of a whole finger. In order to assess the sensorized robotic manipulator, a mechatronic validation platform has been developed and employed. Preliminary results show a mechanical decoupling between exteroceptive and proprioceptive functions, and among the spatially distributed outputs of the sensor array. These results demonstrate the potential of the proposed approach towards achieving dexterous and fine capabilities in the manipulation of objects

Single-plane neck movements and respiratory frequency monitoring: a smart system for computer workers

Prolonged seated works are responsible of awkward poses (e.g., excessive neck forward flexion) and job stressful conditions. Musculoskeletal disorders in the cervical spine region are common in computer workers who are often affected by neck pain. Neck pain has a high prevalence amongst the general population (from 42% to 69%). Reduction of workers productivity, absence from work and utilization of health care services worsen the socioeconomic burden associated to neck pain. Early evaluation of postural mistakes and changes in vital signs associated to job stress may be beneficial to reduce the incidence of neck pain. To reach this aim, wearable systems based on different sensing technologies have been developed. In the last decades, smart systems based on fiber Bragg grating sensors (FBGs) have been extensively used for instrumenting wearables. The present work aimed at preliminary assessing the capability of an FBG-based smart system in detecting single-plane neck movements associated to poor postural habits and respiratory frequency changes associated to stressful working conditions. Results confirmed the system capability in detecting flexion/extension movements in the sagittal plane and its good accuracy in monitoring respiratory frequency during computer work

Increased symmetry of lower-limb amputees walking with concurrent bilateral vibrotactile feedback

Gait asymmetry in lower-limb amputees can lead to several secondary conditions that can decrease general health and quality of life. Including augmented sensory feedback in rehabilitation programs can effectively mitigate spatiotemporal gait irregularities. Such benefits can be obtained with non-invasive haptic systems representing an advantageous choice for usability in overground training and every-day life. In this study, we tested a wearable tactile feedback device delivering short-lasting (100 ms) vibrations around the waist syncronized to gait events, to improve the temporal gait symmetry of lower-limb amputees. Three above-knee amputees participated in the study. The device provided bilateral stimulations during a training program that involved ground-level gait training. After three training sessions, participants showed higher temporal symmetry when walking with the haptic feedback in comparison to their natural walking (resulting symmetry index increases of +2.8% for Subject IDA, +12.7% for Subject IDB and +2.9% for Subject IDC). One subject retained improved symmetry (Subject IDB, +14.9%) even when walking without the device. Gait analyses revealed that higher temporal symmetry may lead to concurrent compensation strategies in the trunk and pelvis. Overall, the results of this pilot study confirm the potential utility of sensory feedback devices to positively influence gait parameters when used in supervised settings. Future studies shall clarify more precisely the training modalities and the targets of rehabilitation programs with such devices

Design and Development of Large-Area FBG-Based Sensing Skin for Collaborative Robotics

Advancements in the field of collaborative robotics have led to a closer cooperation between humans and machines. Sharing the same environment, safety and adaptive control becomes of paramount importance in human-robot interaction. Thus, tactile feedback technologies are crucial to perceive contacts. This work presents the design and development of a polymeric artificial skin, mimicking the human sense of touch in perceiving and localizing pressure over a large area, and its integration on a custom human-like robotic forearm. The sensing system consisted of a curved soft matrix embedding an optical fiber equipped with 16 distributed Fiber Bragg Gratings (FBGs). To estimate the sensitivity of the tactile sensor array, a preliminary mechanical characterization was performed by means of force-controlled indentations. Results show a high correlation between the applied load and the corresponding output of the sensors. In particular, the median value of the sensitivity resulted in 0.26 nm.N-1, with 0.08 nm.N-1 interquartile range. These promising results call for further investigation on spatial sensitivity and force range, contact localization and calibration of the presented artificial skin