517 research outputs found
Sensors for Robotic Hands: A Survey of State of the Art
Recent decades have seen significant progress in the field of artificial hands. Most of the
surveys, which try to capture the latest developments in this field, focused on actuation and control systems of these devices. In this paper, our goal is to provide a comprehensive survey of the sensors for artificial hands. In order to present the evolution of the field, we cover five year periods starting at the turn of the millennium. At each period, we present the robot hands with a focus on their sensor systems dividing them into categories, such as prosthetics, research devices, and industrial end-effectors.We also cover the sensors developed for robot hand usage in each era. Finally, the period between 2010 and 2015 introduces the reader to the state of the art and also hints to the future directions in the sensor development for artificial hands
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A novel design process of low cost 3D printed ambidextrous finger designed for an ambidextrous robotic hand
This paper presents the novel mechanical design of an ambidextrous finger specifically designed for an ambidextrous anthropomorphic robotic hand actuated by pneumatic artificial muscles. The ambidextrous nature of design allows fingers to perform both left and right hand movements. The aim of our design is to reduce the number of actuators, increase the range of movements with best possible range ideally greater than a common human finger. Four prototypes are discussed in this paper; first prototype is focused on the choice of material and to consider the possible ways to reduce friction. Second prototype is designed to investigate the tendons routing configurations. Aim of third and fourth prototype is to improve the overall performance and to maximize the grasping force. Finally, a unified design (Final design) is presented in great detail. Comparison of all prototypes is done from different angles to evaluate the best design. The kinematic features of intermediate mode have been analysed to optimize both the flexibility and the robustness of the system, as well as to minimize the number of pneumatic muscles. The final design of an ambidextrous finger has developed, tested and 3D printed
Segmented capacitance tomography electrodes: a design and experimental verifications
A segmented capacitance tomography system for real-time imaging of multiphase flows is developed and pre-sented in this work. The earlier research shows that the electrical tomography (ECT) system is applicable in flow visualization (image reconstruction). The acquired concentration profile ob-tained from capacitance measurements able to imaged liquid and gas mixture in pipelines meanwhile the system development is designed to attach on a vessel. The electrode plates which act as the sensor previously has been assembled and fixed on the pipeline, thus it causes obscurity for the production to have any new process installation in the future. Therefore, a segmented electrode sensor offers a new design and idea on ECT system which is portable to be assembled in different diameter sizes of pipeline, and it is flexible to apply in any number due to different size of pipeline without the need of redesigning the sensing module. The new ap-proach of this sensing module contains the integration intelligent electrode sensing circuit on every each of electrode sensors. A microcontroller unit and data acquisition (DAQ) system has been integrated on the electrode sensing circuit and USB technology was applied into the data acquisition system making the sensor able to work independently. Other than that the driven guard that usually placed between adjacent measuring electrodes and earth screen has been embedded on the segmented electrode sensor plates. This eliminates the cable noise and the electrode, so the signal conditioning board can be expanded according to pipe diameter
Hubungan di antara pengaturan kerja fleksibel dan prestasi pekerja dalam kalangan ejen insurans wanita
Ejen insurans merupakan jurujual pertengahan bagi syarikat insurans di mana mereka memainkan peranan penting dalam memberi khidmat nasihat kewangan (Hannah, 2011). Ejen insurans bekerja berdasarkan persekitaran pengaturan kerja yang fleksibel di mana mereka boleh menyediakan jadual waktu bekerja sendiri. Sebahagian daripada mereka bertemu dengan pelanggan pada waktu perniagaan siang hari, sementara yang lain pula membuat kertas kerja dan menyediakan konsultasi untuk pelanggan pada waktu petang. Kebanyakan mereka bekerja selama 40 jam seminggu dan ada juga beberapa ejen yang bekerja lebih lama daripada 40 jam (Hannah, 2011). Prestasi ejen insurans sangat penting untuk mengekalkan jenama produk insurans. Penilaian terhadap prestasi di kalangan ejen insurans biasanya bergantung kepada kejayaan atau kegagalan mencapai sasaran penjualan (Insurance Agent Job Overview, 2019). Proses menjual produk insurans memerlukan masa kerana mereka perlu mendekati pelanggan sebanyak mungkin dan ketersediaan waktu bekerja yang tidak tetap
Data-Driven Grasp Synthesis - A Survey
We review the work on data-driven grasp synthesis and the methodologies for
sampling and ranking candidate grasps. We divide the approaches into three
groups based on whether they synthesize grasps for known, familiar or unknown
objects. This structure allows us to identify common object representations and
perceptual processes that facilitate the employed data-driven grasp synthesis
technique. In the case of known objects, we concentrate on the approaches that
are based on object recognition and pose estimation. In the case of familiar
objects, the techniques use some form of a similarity matching to a set of
previously encountered objects. Finally for the approaches dealing with unknown
objects, the core part is the extraction of specific features that are
indicative of good grasps. Our survey provides an overview of the different
methodologies and discusses open problems in the area of robot grasping. We
also draw a parallel to the classical approaches that rely on analytic
formulations.Comment: 20 pages, 30 Figures, submitted to IEEE Transactions on Robotic
A Grasp Pose is All You Need: Learning Multi-fingered Grasping with Deep Reinforcement Learning from Vision and Touch
Multi-fingered robotic hands could enable robots to perform sophisticated
manipulation tasks. However, teaching a robot to grasp objects with an
anthropomorphic hand is an arduous problem due to the high dimensionality of
state and action spaces. Deep Reinforcement Learning (DRL) offers techniques to
design control policies for this kind of problems without explicit environment
or hand modeling. However, training these policies with state-of-the-art
model-free algorithms is greatly challenging for multi-fingered hands. The main
problem is that an efficient exploration of the environment is not possible for
such high-dimensional problems, thus causing issues in the initial phases of
policy optimization. One possibility to address this is to rely on off-line
task demonstrations. However, oftentimes this is incredibly demanding in terms
of time and computational resources. In this work, we overcome these
requirements and propose the A Grasp Pose is All You Need (G-PAYN) method for
the anthropomorphic hand of the iCub humanoid. We develop an approach to
automatically collect task demonstrations to initialize the training of the
policy. The proposed grasping pipeline starts from a grasp pose generated by an
external algorithm, used to initiate the movement. Then a control policy
(previously trained with the proposed G-PAYN) is used to reach and grab the
object. We deployed the iCub into the MuJoCo simulator and use it to test our
approach with objects from the YCB-Video dataset. The results show that G-PAYN
outperforms current DRL techniques in the considered setting, in terms of
success rate and execution time with respect to the baselines. The code to
reproduce the experiments will be released upon acceptance.Comment: Submitted to IROS 202
The role of morphology of the thumb in anthropomorphic grasping : a review
The unique musculoskeletal structure of the human hand brings in wider dexterous capabilities to grasp and manipulate a repertoire of objects than the non-human primates. It has been widely accepted that the orientation and the position of the thumb plays an important role in this characteristic behavior. There have been numerous attempts to develop anthropomorphic robotic hands with varying levels of success. Nevertheless, manipulation ability in those hands is to be ameliorated even though they can grasp objects successfully. An appropriate model of the thumb is important to manipulate the objects against the fingers and to maintain the stability. Modeling these complex interactions about the mechanical axes of the joints and how to incorporate these joints in robotic thumbs is a challenging task. This article presents a review of the biomechanics of the human thumb and the robotic thumb designs to identify opportunities for future anthropomorphic robotic hands
Graphite immobilisation in glass composite materials
Irradiated graphite is a problematic nuclear waste stream and currently raises significant concern
worldwide in identifying its long-term disposal route. This thesis describes the use of glass
materials for the immobilisation of irradiated graphite prepared by microwave, conventional and
sparks plasma sintering methods. Several potential glass compositions namely iron phosphate,
aluminoborosilicate, calcium aluminosilicate, alkali borosilicate and obsidian were considered
for the immobilisation of various loadings of graphite simulating irradiated graphite. The
properties of the samples produced using different processing methods are compared selectively.
An investigation of microwave processing using an iron phosphate glass composition revealed
that full reaction of the raw materials and formation of a glass melt occurs with consequent
removal of porosity at 8 minutes microwave processing. When graphite is present, iron
phosphate crystalline phases are formed with much higher levels of residual porosity of up to 43
% than in the samples prepared using conventional sintering under argon. It is found that
graphite reacts with the microwave field when in powder form but this reaction is minimised
when the graphite is incorporated into a pellet, and that the graphite also impedes sintering of the
glass. Mössbauer spectroscopy indicates that reduction of iron occurs with concomitant graphite
oxidation. The production of graphite-glass samples using various powdered glass compositions
by conventional sintering method still resulted in high porosity with an average of 6-17 % for
graphite loadings of 20-25 wt%. Due to the use of pre-made glasses and controlled sintering
parameters, the loss of graphite from the total mass is reduced compared to the microwaved
samples; the average mass loss is < 0.8 %. The complication of iron oxidation and reduction is
present in all the iron containing base glasses considered and this increases the total porosity of
the graphite-glass samples. It is concluded that the presence of iron in the raw materials or base
glasses as an encapsulation media for the immobilisation of the irradiated graphite waste is not
advisable. The production of glass and graphite-glass samples based calcium aluminosilicate
composition by spark plasma sintering method is found highly suitable for the immobilisation of
irradiated graphite wastes. The advantages of the method includes short processing time i.e. < 40
minutes, improved sintering transport mechanisms, limited graphite oxidation, low porosity (1-4
%) and acceptable tensile strength (2-7 MPa). The most promising samples prepared using spark
plasma sintering method were loaded with 30-50 wt% graphite
A Methodology for the Design of Robotic Hands with Multiple Fingers
This paper presents a methodology that has been applied for a design process of anthropomorphic hands with multiple fingers. Biomechanical characteristics of human hand have been analysed so that ergonomic and anthropometric aspects have been used as fundamental references for obtaining grasping mechanisms. A kinematic analysis has been proposed to define the requirements for designing grasping functions. Selection of materials and actuators has been discussed too. This topic has been based on previous experiences with prototypes that have been developed at the Laboratory of Robotics and Mechatronics (LARM) of the University of Cassino. An example of the application of the proposed method has been presented for the design of a first prototype of LARM Hand
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