Measurement of human rotation behavior for psychological and neuropsychological investigations

The investigation of rotation behavior in human beings enjoys a longstanding and enduring interest in laterality research. While in animal studies the issue of accurately measuring the number of rotations has been solved and is widely applied in practice, it is still challenging to assess the rotation behavior of humans in daily life. We propose a robust method to assess human rotation behavior based on recordings from a miniature inertial measurement unit that can be worn unobtrusively on a belt. We investigate the effect of different combinations of low-cost sensors—including accelerometers, gyroscopes, and magnetometers—on rotation measurement accuracy, propose a simple calibration procedure, and validate the method on data from a predefined path through and around buildings. Results suggest that a rotation estimation based on the fusion of accelerometer, gyroscope, and magnetometer measurements outperforms methods based solely on earth magnetic field measurements, as proposed in previous studies, by a drop in error rate of up to 32 %. We further show that magnetometer signals do not significantly contribute to measurement accuracy in short-term measurements, and could thus be omitted for improved robustness in environments with magnetic field disturbances. Results also suggest that our simple calibration procedure can compete with more complex approaches and reduce the error rate of the proposed algorithm by up to 38 %

Measurement of Human Rotation Behavior for Psychological and Neuropsychological Investigations

ISSN:1554-351XISSN:1554-352

ARAKNES haptic interface: user-centered design approach

Minimally Invasive Surgery (MIS) methods have revolutionized surgical care, considerably improving the results of many surgical procedures. Technological advances, in particular in robotic surgical systems, have reduced the complexity of this surgical method enhancing a surgeon's dexterity, precision and visualization. Despite all these advantages, the progress in this field is constrained by an unsolved issue: the introduction of MIS has eliminated the possibility of direct organ manipulation and palpation. Nowadays, the majority of the robotic surgical systems do not provide suitable haptic feedback integrating both kinaesthetic (force and position) and tactile information. Although, haptics is a very active field of research due to its potential application in robotic surgical systems, most of the commercially available devices provide only kinesthetic feedback. Within ARAKNES project, we are developing a bimanual haptic workstation to teleoperate surgical micro-robots located in the abdominal cavity of the patient. Our final goal is to develop a haptic interface that provides to the surgeon the kinesthetic and tactile feedback that he/she is missing because of the indirect manipulation of the distal organs. In this abstract, we described the user-centered design approach chosen for the compilation of both the functional and ergonomic specifications of the device. Two examples of design iteration are presented to illustrate the proposed

A method to qualitatively assess arm use in stroke survivors in the home environment

Wearable sensor technology has enabled unobtrusive monitoring of arm movements of stroke survivors in the home environment. However, the most widely established method, based on activity counts, provides quantitative rather than qualitative information on arm without functional insights, and is sensitive to passive arm movements during ambulatory activities. We propose a method to quantify functionally relevant arm use in stroke survivors relying on a single wrist-worn inertial measurement unit. Orientation of the forearm during movements is measured in order identify gross arm movements. The method is validated in 10 subacute/chronic stroke survivors wearing inertial sensors at 5 anatomical locations for 48 h. Measurements are compared to conventional activity counts and to a test for gross manual dexterity. Duration of gross arm movements of the paretic arm correlated significantly better with the Box and Block Test (r=0.95) than conventional activity counts when walking phases were included (r=0.69), and similar results were found when comparing ratios of paretic and non-paretic arms for gross movements and activity counts. The proposed gross arm movement metric is robust against passive arm movements during ambulatory activities and requires only a single-sensor module placed at the paretic wrist for the assessment of functionally relevant arm use.ISSN:1741-0444ISSN:0140-011

Activity classification based on inertial and barometric pressure sensors at different anatomical locations

Miniature, wearable sensor modules are a promising technology to monitor activities of daily living (ADL) over extended periods of time. To assure both user compliance and meaningful results, the selection and placement site of sensors requires careful consideration. We investigated these aspects for the classification of 16 ADL in 6 healthy subjects under laboratory conditions using ReSense, our custom-made inertial measurement unit enhanced with a barometric pressure sensor used to capture activity-related altitude changes. Subjects wore a module on each wrist and ankle, and one on the trunk. Activities comprised whole body movements as well as gross and dextrous upper-limb activities. Wrist-module data outperformed the other locations for the three activity groups. Specifically, overall classification accuracy rates of almost 93% and more than 95% were achieved for the repeated holdout and user-specific validation methods, respectively, for all 16 activities. Including the altitude profile resulted in a considerable improvement of up to 20% in the classification accuracy for stair ascent and descent. The gyroscopes provided no useful information for activity classification under this scheme. The proposed sensor setting could allow for robust long-term activity monitoring with high compliance in different patient populations.ISSN:0967-3334ISSN:1361-657

Tactile Feedback Improves Performance in a Palpation Task: Results in a VR-Based Testbed

Robotic surgery provides many benefits such as reduced invasiveness and increased dexterity. This comes at the cost of no direct contact between surgeon and patient This physical separation prevents surgeons from performing direct haptic exploration of tissues and organs, imposing exclusive reliance on visual cues. Current technology is not yet able to both measure and reproduce a realistic and complete sense of touch (interaction force, temperature, roughness, etc.). In this paper, we put forward a concept based on multimodal feedback consisting of the integration of different kinds of visual and tactile cues with force feedback that can potentially improve both the surgeon's performance and the patient's safety. We present a cost-effective tactile display simulating a pulsating artery that has been integrated into a haptic work-station to combine both tactile and force-feedback information. Furthermore, we investigate the effect of different feedback types, including tactile and/or visual cues, on the performance of subjects carrying out two typical palpation tasks: (1) exploring a tissue to find a hidden artery and (2) identifying the orientation of a hidden artery. The results show that adding tactile feedback significantly reduces task completion time. Moreover, for high difficulty levels, subjects perform better with the feedback condition combining tactile and visual cues. As a matter of fact, the majority of the subjects in the study preferred this combined feedback because redundant feedback reassures subjects in their actions. Based on this work, we can infer that multimodal haptic feedback improves subjects' performance and confidence during exploratory procedures

A novel algorithm for detecting active propulsion in wheelchair users following spinal cord injury

Physical activity in wheelchair-bound individuals can be assessed by monitoring their mobility as this is one of the most intense upper extremity activities they perform. Current accelerometer-based approaches for describing wheelchair mobility do not distinguish between self- and attendant-propulsion and hence may overestimate total physical activity. The aim of this study was to develop and validate an inertial measurement unit based algorithm to monitor wheel kinematics and the type of wheelchair propulsion (self- or attendant-) within a "real-world" situation. Different sensor set-ups were investigated, ranging from a high precision set-up including four sensor modules with a relatively short measurement duration of 24 h, to a less precise set-up with only one module attached at the wheel exceeding one week of measurement because the gyroscope of the sensor was turned off. The "high-precision" algorithm distinguished self- and attendant-propulsion with accuracy greater than 93% whilst the long-term measurement set-up showed an accuracy of 82%. The estimation accuracy of kinematic parameters was greater than 97% for both set-ups. The possibility of having different sensor set-ups allows the use of the inertial measurement units as high precision tools for researchers as well as unobtrusive and simple tools for manual wheelchair users

Dopamine-responsive pattern in tremor patients

BACKGROUND Diagnosis and treatment of tremor are largely based on clinical assessment. Whereas in some patients tremor may respond to dopaminergic treatment, in general l-Dopa response to tremor varies considerably. The aim of this study was to predict l-Dopa response by accelerometry. METHODS We included 60 tremor patients and measured harmonic oscillations by accelerometry. In addition to neurological assessment, we performed l-Dopa challenge tests and the individual tremor response was compared to the amount of harmonic oscillations. RESULTS We found a strong correlation between harmonic oscillations and clinical l-Dopa response. Similarly, harmonic oscillations were significantly greater in patients with subjective tremor reduction upon l-Dopa administration. CONCLUSIONS We conclude that harmonic oscillations are a measure for l-Dopa response to tremor irrespective of the underlying disease. Because of the observational character of the study, any causal relation remains speculative. Nevertheless, we propose a novel, non-invasive approach to predict l-Dopa response in tremor patients