1,720,965 research outputs found
Analysis of bend-over gesture wearing a trunk-support exoskeleton
Full text linkIn the context of industrial tasks, back exoskeletons aim at reducing operator’s muscular effort during the work gesture and prevent professional illnesses. Passive devices have the limitation of providing fixed support based on a single angle of bending kinematics. In this study, a multibody model previously validated was used to evaluate the biomechanical effects of assistance provided by passive exoskeletons in terms of joint actions. Specifically, the model, which involves the DOF allowed by the spine in the waist joint, reproduced experimental kinematics of two subjects realizing stoops and squats at various speeds. Kinematics was measured using an active exoskeleton prototype developed by the authors and inertial sensors (IMUs). Simulations revealed that passive assistance results in joint internal reactions mainly along the sagittal axis, which may lead to discomfort and instability in squat bending. Results underscore the importance of developing flexible laws for active systems able to adjust support dynamically to users’ movements and preferences
Evaluation of the Maneuvering Assistance Effectiveness of Two Wheelchair Powered Assistance Devices
No full textWhile manual wheelchairs are crucial for individuals with reduced mobility, many users encounter challenges due to physical limitations. To address these challenges, various power assistive devices, including rear add-ons, have been developed. However, concerns persist among users regarding safety and control methods, especially during turning and manoeuvring. This study explores the effectiveness of two types of commercial rear add-on power assistive devices in aiding manual wheelchair users during turning manoeuvres. A 3D multibody model was developed to assess the influence of these devices on wheelchair dynamics. The model includes a wheelchair multibody model and two rear add-ons: a drive caster wheel that passively reorients, and a drive omniwheel. The impact of these devices on wheelchair dynamics during turning manoeuvres was evaluated. Results indicate that both devices exert pushing forces opposing the user’s action during turning. The drive caster wheel provides a positive torque to assist the user in the curve, although it is delayed. Conversely, the drive omniwheel offers slight opposing turning torque but do not assist user in performing the manoeuvre
Demonstration of real-time event camera to collaborative robot communication
Full text linkReal-time robot actuation is one of the main challenges to overcome in human-robot interaction. Most visual sensors are either too slow or their data are too complex to provide meaningful information and low latency input to a robotic system. Data output of an event camera is high-frequency and extremely lightweight, with only 8 bytes per event. To evaluate the hypothesis of using event cameras as data source for a real-time robotic system, the position of a waving hand is acquired from the event data and transmitted to a collaborative robot as a movement command. A total time delay of 110 ms was measured between the original movement and the robot movement, where much of the delay is caused by the robot dynamics
Comprehensive Control Strategy Design for a Wheelchair Power-Assist Device
Full text linkRear add-ons are assistive devices developed to assist users who have difficulty propelling wheelchairs. Improving the mobility of wheelchair users and allowing them access to more activities is in line with the objective of the sustainable development goals SDG3, and SDG11. Currently, commercial rear add-on devices implement speed-based controls. The speed-based control consists in setting the reference speed that the device must keep constant which makes rear add-on devices suitable for long journeys but, makes them unsuitable for use in narrow spaces. In this paper an hybrid control is presented. The proposed control law takes into account the thrust exerted by the user (torque-based), the forward speed of the wheelchair (speed-based), as well as the surrounding environmental conditions. The total torque delivered by the device is evaluated as the sum of a contribution proportional to the user’s thrust, a delayed contribution as a function of forward speed, and the gravity compensation contribution. The proportional contribution synchronous with respect to the user’s push at low speeds improves manoeuvrability and controllability of the wheelchair, whereas, at higher speeds, the introduction of the delayed thrust distributes the assistance torque over a longer period, reducing the peak of torque provided by the device. A dynamic multibody model of a wheelchair was also developed and implemented in the Simulink environment to test the proposed control algorithm. As a future step the algorithm will be implemented on a rear add-on device and it will be tested experimentally by wheelchair users
A Dataset of Standard and Abrupt Industrial Gestures Recorded Through MIMUs
Full text linkConsidering the human-centric approach promoted by Industry 5.0, safety becomes a crucial aspect in scenarios of human–robot interaction, especially when abrupt human movements occur due to inattention or unexpected circumstances. To this end, human motion tracking is necessary to promote a safe and efficient human–machine interaction. Literature datasets related to the industrial context generally contain controlled and repetitive gestures tracked with visual systems or magneto-inertial measurement units (MIMUs), without considering the occurrence of unexpected events that might cause operators’ abrupt movements. Accordingly, the aim of this paper is to present the dataset DASIG (Dataset of Standard and Abrupt Industrial Gestures) related to both standard typical industrial movements and abrupt movements registered through MIMUs. Sixty healthy working-age participants were asked to perform standard pick-and-place gestures interspersed with unexpected abrupt movements triggered by visual or acoustic alarms. The dataset contains MIMUs signals collected during the execution of the task, data related to the temporal generation of alarms, anthropometric data of all participants, and a script for demonstrating DASIG usability. All raw data are provided, and the collected dataset is suitable for several analyses related to the industrial context (gesture recognition, motion planning, ergonomics, safety, statistics, etc.)
A Hands-On Platform for Learning Human-Robot Collaboration Using Gesture-Controlled Robotics
No full textIndustry 5.0 wants to place the human being at the centre of the industrial context, structuring technology in such a way that the operators become an integral part of the production cycle. In addition to productivity, the systems must dynamically adapt to the human’s needs, considering the well-being of the operators. Following these aims a human-machine application was developed with an educational purpose. This involves a collaborative robot interaction with an operator through the reading and interpretation of kinematic signals from inertial sensors. The activity was designed to provide students, particularly those with a mechanical background, with both an introduction to collaborative robotics and a straightforward understanding and visualization of the theoretical concepts, along with practical aspects such as ROS programming, and hardware implementation of microcontrollers and sensors. Through a hands-on approach, students will have firsthand interaction with the test bench, putting previously learned theoretical concepts into practice, following the principle of learn-by-doing
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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