bluuebunny/crossref_metadata_2025 huggingface dataset:
Standard Koszul self-injective special biserial algebras
Authors: Magyar András
Published: March 2015

The aim of this paper is to establish a connection between the standard Koszul and the quasi-Koszul property in the class of self-injective special biserial algebras. Furthermore, we give a characterization of standard Koszul symmetric special biserial algebras in terms of quivers and relations.
Finite groups with each non-normal subgroup having maximal normal cores
Authors: Lv Heng , Shao Zhibo , Zhou Wei
Published: March 2015

In this paper, we study a finite group [Formula: see text] such that [Formula: see text] is a prime for each non-normal subgroup [Formula: see text] of [Formula: see text]. We prove that such a group must contain a big abelian subgroup. More specifically, if such a group [Formula: see text] is not supersoluble, then there is an abelian subgroup [Formula: see text] such that [Formula: see text], and if [Formula: see text] is supersoluble, then there is an abelian subgroup [Formula: see text] such that [Formula: see text] or [Formula: see text], where [Formula: see text] and [Formula: see text] are primes.
Some sufficient conditions on solvability of finite groups
Authors: Meng Wei , Lu Jiakuan , Ma Li , Ma Wanqing
Published: March 2015

For a finite group [Formula: see text], the symbol [Formula: see text] denotes the set of the prime divisors of [Formula: see text] denotes the number of conjugacy classes of maximal subgroups of [Formula: see text]. Let [Formula: see text] denote the number of conjugacy classes of non-abelian subgroups of [Formula: see text] and [Formula: see text] denote the number of conjugacy classes of all non-normal non-abelian subgroups of [Formula: see text]. In this paper, we consider the finite groups with [Formula: see text] or [Formula: see text]. We show these groups are solvable.
EVOLUTIONARY DYNAMICS IN OPINION FORMATION MODEL WITH COUPLING OF SOCIAL COMMUNITIES
Authors: XU WEN-JUAN , ZHONG LI-XIN , HUANG PING , QIU TIAN , SHI YONG-DONG , ZHONG CHEN-YANG
Published: March 2015

By incorporating multi-community attachments into the continuous opinion formation model, we investigate the driving force for reaching consensus in networked systems. A phase transition from fragmentation to consensus is determined by the multiplex network structures and the coupling of different communities. A moderate number of layers and weak coupling are beneficial for consensus. The evolutionary dynamics in the present model is governed by the prolonged evolutionary time, which results from the disparities of individual opinions in different communities. Increasing the multiple layers is similar to promoting coupling between different communities. A functional relation between the convergence time and the coupling coefficient is found.
RANKING DEVELOPER CANDIDATES BY SOCIAL LINKS
Authors: XUAN QI , FU CHENBO , YU LI
Published: March 2015

In open source software (OSS) projects, participants initially communicate with others and then may become developers if they are deemed worthy by the community. Recent studies indicate that the abundance of established social links of a participant is the strongest predictor to his/her promotion. Having reliable rankings of the candidates is key to recruiting and maintaining a successful operation of an OSS project. This paper adopts degree-based, PageRank, and Hits ranking algorithms to rank developer candidates in OSS projects based on their social links. We construct several types of social networks based on the communications between the participants in Apache OSS projects, then train and test the ranking algorithms in these networks. We find that, for all the ranking algorithms under study, the rankings of emergent developers in temporal networks are higher than those in cumulative ones, indicating that the more recent communications of a developer in a project are more important to predict his/her first commit in the project. By comparison, the simple degree-based and the PageRank ranking algorithms in temporal undirected weighted networks behave better than the others in identifying emergent developers based on four performance indicators, and are thus recommended to be applied in the future.
CUMULATIVE EFFECTS RESEARCH: ACHIEVEMENTS, STATUS, DIRECTIONS AND CHALLENGES IN THE CANADIAN CONTEXT
Authors: NOBLE BRAM
Published: March 2015

This paper reflects on the state of cumulative effects research in Canada and future directions and challenges. The assessment and management of cumulative effects has been an enduring theme in the impact assessment literature, and scholars have consistently identified the challenges to assessing and managing cumulative effects under regulatory, project-based impact assessment. Current research on cumulative effects is focused largely on the development of frameworks and methodologies to advance cumulative effects assessment and management from individual projects to broader regional scales, and on developing the science and tools for assessing and monitoring cumulative effects. Ensuring that scholarly research continues to shape cumulative effects practice in the future requires that scholars not only attempt to improve practice under current existing regulatory processes, but also push the boundaries to ensure that decision processes also evolve so as to be accommodating of new and innovative approaches to cumulative effects at regional scales. This requires interdisciplinary approaches and sustained research funding, both of which present practical challenges to scholars, and research programmes that are developed in collaboration with industry, governments and communities.
Online Updates on Data Warehouses via Judicious Use of Solid-State Storage
Authors: Athanassoulis Manos , Chen Shimin , Ailamaki Anastasia , Gibbons Philip B. , Stoica Radu
Published: March 2015

Data warehouses have been traditionally optimized for read-only query performance, allowing only offline updates at night, essentially trading off data freshness for performance. The need for 24x7 operations in global markets and the rise of online and other quickly reacting businesses make concurrent online updates increasingly desirable. Unfortunately, state-of-the-art approaches fall short of supporting fast analysis queries over fresh data. The conventional approach of performing updates in place can dramatically slow down query performance, while prior proposals using differential updates either require large in-memory buffers or may incur significant update migration cost.

This article presents a novel approach for supporting online updates in data warehouses that overcomes the limitations of prior approaches by making judicious use of available SSDs to cache incoming updates. We model the problem of query processing with differential updates as a type of outer join between the data residing on disks and the updates residing on SSDs. We present
MaSM
algorithms for performing such joins and periodic migrations, with small memory footprints, low query overhead, low SSD writes, efficient in-place migration of updates, and correct ACID support. We present detailed modeling of the proposed approach, and provide proofs regarding the fundamental properties of the
MaSM
algorithms. Our experimentation shows that MaSM incurs only up to 7% overhead both on synthetic range scans (varying range size from 4KB to 100GB) and in a TPC-H query replay study, while also increasing the update throughput by orders of magnitude.
Using Weightless Neural Networks for Vergence Control in an Artificial Vision System
Authors: Komati Karin S. , De Souza Alberto F.
Published: March 2015

This paper presents a methodology we have developed and used to implement an artificial binocular vision system capable of emulating the vergence of eye movements. This methodology involves using weightless neural networks (WNNs) as building blocks of artificial vision systems. Using the proposed methodology, we have designed several architectures of WNN-based artificial vision systems, in which images captured by virtual cameras are used for controlling the position of the ‘foveae’ of these cameras (high-resolution region of the images captured). Our best architecture is able to control the foveae vergence movements with average error of only 3.58 image pixels, which is equivalent to an angular error of approximately 0.629°.
Why the Left Ventricle Is Not a Sphere
Authors: Blyakhman Felix A. , Shklyar Tatyana F. , Pavlov Ivan A. , Sokolov Sergey Yu , Grinko Alexey A.
Published: March 2015

In this study, we have tried to understand why the left ventricle (LV) is not a homogeneous sphere. An experimental model of a spherical ventricle was developed. The chamber was configured as a mathematical model, and the wall properties were represented by isolated cardiac muscles. The stroke work of the spherical LV when modelling different types of inhomogeneity in the wall structure was investigated. It was found that the emergence of even slight inhomogeneity in a spherical ventricle inevitably results in a diminution of pump function. It was concluded that at a given level of the myocardial contractility, a homogeneous spherical LV would not have any functional reserve, ie no ability to maintain pump function in case of additional load. Functional reserve can be achieved only with a certain degree of inhomogeneity. Thus, inhomogeneity in the normal left ventricular wall structure constitutes a strategic functional reserve that is absent in a homogeneous spherical ventricle.
Smart Structures and Intelligent Systems for Health Monitoring and Diagnostics
Authors: El-Sherif M. A.
Published: March 2015

“Smart and intelligent” structures are defined as structures capable of monitoring their own “health” condition and structural behavior, such structures are capable of sensing external environmental conditions, making decisions, and sending the information to other locations. Available conventional devices and systems are not technologically mature for such applications. New classes of miniature devices and networking systems are urgently needed for such applications. In this paper, two examples of the successful work achieved so far, in biomedical application of smart structures, are presented. The first one is based on the development of a smart bone fixation device for rehabilitation and treatment. This device includes a smart composite bar that can sense physical stress applied to the fractured bones, and send the information to the patient's physician remotely. The second is on the development of smart fabrics for many applications including health monitoring and diagnostics. Successful development of such smart fabrics with embedded fiber optic sensors and networks is mainly dependent on the development of the proper miniature sensor technology, and on the integration of these sensors into textile structures. The developed smart structures will be discussed and samples of the results will be presented.
Homogenization of Heterogeneous Tissue Scaffold: A Comparison of Mechanics, Asymptotic Homogenization, and Finite Element Approach
Authors: Fang Z. , Yan C. , Sun W. , Shokoufandeh A. , Regli W.
Published: March 2015

Actual prediction of the effective mechanical properties of tissue scaffolds is very important for tissue engineering applications. Currently common homogenization methods are based on three available approaches: standard mechanics modeling, homogenization theory, and finite element methods. Each of these methods has advantages and limitations. This paper presents comparisons and applications of these approaches for the prediction of the effective properties of a tissue scaffold. Derivations and formulations of mechanics, homogenization, and finite element approach as they relate to tissue engineering are described. The process for the development of a computational algorithm, finite element implementation, and numerical solution for calculating the effective mechanical properties of porous tissue scaffolds are also given. A comparison of the results based upon these different approaches is presented. Parametric analyses using the homogenization approach to study the effects of different scaffold materials and pore shapes on the properties of the scaffold are conducted, and the results of the analyses are also presented.
Serpentine Locomotion Articulated Chain: ANA II
Authors: Cardona A. M. , Barrero J. I. , Otálora C. , Parra C.
Published: March 2015

When humanity faces challenges in solving problems beyond their technical resources, and has no foundation to solve a problem, engineering must search for an answer developing new concepts and innovative frameworks to excel these limitations and travel beyond our capabilities. This project “Serpentine locomotion articulated chain: ANA II” is a self-contained robot built to evaluate the behavior of the platform being capable of serpentine movements, in a modular chain mechanical design, based on a master/slave architecture.
A Vision-Based Approach for Estimating Contact Forces: Applications to Robot-Assisted Surgery
Authors: Kennedy C. W. , Desai J. P.
Published: March 2015

The primary goal of this paper is to provide force feedback to the user using vision-based techniques. The approach presented in this paper can be used to provide force feedback to the surgeon for robot-assisted procedures. As proof of concept, we have developed a linear elastic finite element model (FEM) of a rubber membrane whereby the nodal displacements of the membrane points are measured using vision. These nodal displacements are the input into our finite element model. In the first experiment, we track the deformation of the membrane in real-time through stereovision and compare it with the actual deformation computed through forward kinematics of the robot arm. On the basis of accurate deformation estimation through vision, we test the physical model of a membrane developed through finite element techniques. The FEM model accurately reflects the interaction forces on the user console when the interaction forces of the robot arm with the membrane are compared with those experienced by the surgeon on the console through the force feedback device. In the second experiment, the PHANToM haptic interface device is used to control the Mitsubishi PA-10 robot arm and interact with the membrane in real-time. Image data obtained through vision of the deformation of the membrane is used as the displacement input for the FEM model to compute the local interaction forces which are then displayed on the user console for providing force feedback and hence closing the loop.
Visual Warning Signals Optimized for Human Perception: What the Eye Sees Fastest
Authors: Gros B. L. , Greenhouse D. S. , Cohn T. E.
Published: March 2015

This study aimed to answer the question of how to design a visual warning signal that is most easily seen and produces the quickest reaction time. This is a classic problem of bionic optimization—if one knows the properties of the receiver one can most easily find a suitable solution. Because the peak of the spatio-temporal contrast sensitivity function of the human visual system occurs at non-zero spatial and temporal frequencies, it is likely that movement enhances the detectability of threshold visual signals. Earlier studies employing extended drifting sinewave gratings bear out this prediction. We have studied the ability of human observers to detect threshold visual signals for both moving and stationary stimuli. We used discrete, localized signals such as might be employed in aerospace or automotive warning signal displays. Moving stimuli show a superior detectability to non-moving stimuli of the same integrated energy. Moving stimuli at threshold detectability are seen faster than non-moving threshold stimuli. Under some conditions the speed advantage is over 0.25 seconds. Similar advantages have also been shown to occur for suprathreshold signals.
Development of a Micro Swimming Robot Using Optimised Giant Magnetostrictive Thin Films
Authors: Zhang Y. , Liu G. , Li H.
Published: March 2015

A fish-like swimming micro robot is developed using an optimised fin actuator made of giant magnetostrictive films (GMFs). The force oscillation dynamic model of a GMF cantilever with variable cross-section area is derived, and the propulsive model of the fish robot in liquid is established. A discrete variate method for optimising caudal fin configuration is proposed to optimise its propulsive force and drive efficiency under the constraints of fixed surface area and sufficient fin end strength. Both theoretical analysis and experimental results have confirmed that the optimised caudal fin configuration can generate more powerful propulsion and improved efficiency.
Haptic Manipulation of Deformable Objects in Hybrid Bilateral Teleoperation System
Authors: Ibarra-Zannatha Juan Manuel , Marmolejo-Rivas Claudia , Ferre-Pérez Manuel , Aracil-Santonja Rafael , Cobos-Guzmán Salvador
Published: March 2015

The aim of this work is the integration of a virtual environment containing a deformable object, manipulated by an open kinematical chain virtual slave robot, to a bilateral teleoperation scheme based on a real haptic device. The virtual environment of this hybrid bilateral teleoperation system combines collision detection algorithms, dynamical, kinematical and geometrical models with a position–position and/or force–position bilateral control algorithm, to produce on the operator side the reflected forces corresponding to the virtual mechanical interactions, through a haptic device. Contact teleoperation task over the virtual environment with a flexible object is implemented and analysed.
Operation Strategy for a Low-Cost Easy-Operation Cassino Hexapod
Authors: Carbone Giuseppe , Shrot Aviral , Ceccarelli Marco
Published: March 2015

This paper presents operation strategies for a hexapod walking machine that has been designed and built at the Laboratory of Robotics and Mechatronics (LARM) at the University of Cassino. Special care has been addressed in proposing and describing a suitable mechanical design and architecture that can be easily operated by a PLC with on–off logic. Experimental tests are reported in order to show feasibility and operational capability of the proposed design.
Minimizing Human Intervention in the Development of Basal Ganglia-Inspired Robot Control
Authors: Montes-Gonzalez F. , Prescott T. J. , Negrete-Martinez J.
Published: March 2015

A biologically inspired mechanism for robot action selection, based on the vertebrate basal ganglia, has been previously presented (Prescottet al. 2006, Montes Gonzalezet al. 2000). In this model the task confronting the robot is decomposed into distinct behavioural modules that integrate information from multiple sensors and internal state to form ‘salience’ signals. These signals are provided as inputs to a computational model of the basal ganglia whose intrinsic processes cause the selection by disinhibition of a winning behaviour. This winner is then allowed access to the motor plant whilst losing behaviours are suppressed. In previous research we have focused on the development of this biomimetic selection architecture, and have therefore used behavioural modules that were hand-coded as algorithmic procedures. In the current article, we demonstrate the use of genetic algorithms and gradient–descent learning to automatically generate/tune some of the modules that generate the model behaviour.
The SAHR Setup-Controlling Hopping Speed and Height Using a Single Actuator
Authors: Cherouvim N. , Papadopoulos E.
Published: March 2015

In this paper we present and experimentally validate a control method for regulating both the forward speed and the apex height of a one-legged hopping robot, using only a single actuator. The control method is based on a dynamic model of the hopping robot and makes use of the dynamic coupling of the vertical and forward motions of the robot. The control is applied first to a simulated model of the robot and shown to track a desired forward robot speed and a desired apex height. Then the SAHR (single actuator hopping robot) hardware is introduced and is used as an experimental platform with which to evaluate the performance of the control method. The control method is applied to the physical setup and is shown to lead to a stable hopping gait with a desired forward speed and apex height, despite the unmodelled disturbances met on the laboratory floor.
Behaviour Generation in Humanoids by Learning Potential-Based Policies from Constrained Motion
Authors: Howard Matthew , Klanke Stefan , Gienger Michael , Goerick Christian , Vijayakumar Sethu
Published: March 2015

Movement generation that is consistent with observed or demonstrated behaviour is an efficient way to seed movement planning in complex, high-dimensional movement systems like humanoid robots. We present a method for learning potential-based policies from constrained motion data. In contrast to previous approaches to direct policy learning, our method can combine observations from a variety of contexts where different constraints are in force, to learn the underlying unconstrained policy in form of its potential function. This allows us to generalise and predict behaviour where novel constraints apply. We demonstrate our approach on systems of varying complexity, including kinematic data from the ASIMO humanoid robot with 22 degrees of freedom.
Peristaltic Transport of a Particle–Fluid Suspension through a Uniform and Non-Uniform Annulus
Authors: Mekheimer K. S. , Abd Elmaboud Y.
Published: March 2015

This study looks at the influence of an endoscope on the peristaltic flow of a particle–fluid suspension (as blood model) through tubes. A long wavelength approximation through a uniform and non-uniform infinite annulus filled with an incompressible viscous and Newtonian fluid mixed with rigid spherical particles of identical size is investigated theoretically. The inner tube is uniform, rigid and moving with a constant velocity V0, whereas the outer non-uniform tube has a sinusoidal wave travelling down its wall. The axial velocity of the fluid phase uf, particulate phase upand the pressure gradients have been obtained in terms of the dimensionless flow rateQ, the amplitude ratioɸ, particle concentrationC, the velocity constant V0and the radius ratio ϵ (the ratio between the radius of the inner tube and the radius of the outer one at the inlet). Numerical calculations for various values of the physical parameters of interest are carried out for the pressure rise and the friction force on the inner and the outer tubes.
Soft Robotics: Biological Inspiration, State of the Art, and Future Research
Authors: Trivedi Deepak , Rahn Christopher D. , Kier William M. , Walker Ian D.
Published: March 2015

Traditional robots have rigid underlying structures that limit their ability to interact with their environment. For example, conventional robot manipulators have rigid links and can manipulate objects using only their specialised end effectors. These robots often encounter difficulties operating in unstructured and highly congested environments. A variety of animals and plants exhibit complex movement with soft structures devoid of rigid components. Muscular hydrostats (e.g. octopus arms and elephant trunks) are almost entirely composed of muscle and connective tissue and plant cells can change shape when pressurised by osmosis. Researchers have been inspired by biology to design and build soft robots. With a soft structure and redundant degrees of freedom, these robots can be used for delicate tasks in cluttered and/or unstructured environments. This paper discusses the novel capabilities of soft robots, describes examples from nature that provide biological inspiration, surveys the state of the art and outlines existing challenges in soft robot design, modelling, fabrication and control.
Finite-Element-Based Design Optimisation of a Novel High Flexion Knee Used in Total Knee Arthroplasty
Authors: Sivarasu Sudesh , Mathew Lazar
Published: March 2015

The application of finite-element modelling in medical applications has been evolving as a field of high importance in recent times. Total knee arthroplasty (TKA) has been in existence for over 6 decades. The generic artificial knee implants used in the TKA have a restricted range of motion of around 90 degrees. A new design allowing a flexion extension range of over 120 degrees was designed and is used for analysis. Loading conditions of 10 times the body weight are considered. The finite-element analyses of the designs were carried out based on standard biomaterials used in orthopaedic implants. The results of the analyses were used in identifying areas of extreme stress within the design and the spots prone to higher deformation. On the basis of these results slight modification of the designs was carried out. The results are also verified whether the body is within the linear deformation levels. The results obtained were very satisfactory and based on these results the models have been recommended for prototyping.
Forward Models Applied in Visual Servoing for a Reaching Task in the iCub Humanoid Robot
Authors: Gamarra Daniel Fernando Tello , Pinpin Lord Kenneth , Laschi Cecilia , Dario Paolo
Published: March 2015

This paper details the application of a forward model to improve a reaching task. The reaching task must be accomplished by a humanoid robot with 53 degrees of freedom (d.o.f.) and a stereo-vision system. We have explored via simulations a new way of constructing and utilizing a forward model that encodes eye–hand relationships. We constructed a forward model using the data obtained from only a single reaching attempt. ANFIS neural networks are used to construct the forward model, but the forward model is updated online with new information that comes from each reaching attempt. Using the obtained forward model, an initial image Jacobian is estimated and is used with a visual servoing controller. Simulation results demonstrate that errors are lower when the initial image Jacobian is derived from the forward model. This paper is one of the few attempts at applying visual servoing in a complete humanoid robot.
Construction of Gait Adaptation Model in Human Splitbelt Treadmill Walking
Authors: Otoda Yuji , Kimura Hiroshi , Takase Kunikatsu
Published: March 2015

There are a huge number of studies that measure kinematics, dynamics, the oxygen uptake and so on in human walking on the treadmill. Especially in walking on the splitbelt treadmill where the speed of the right and left belt is different, remarkable differences in kinematics are seen between normal and cerebellar disease subjects. In order to construct the gait adaptation model of such human splitbelt treadmill walking, we proposed a simple control model and made a newly developed 2D biped robot walk on the splitbelt treadmill. We combined the conventional limit-cycle based control consisting of joint PD-control, cyclic motion trajectory planning and a stepping reflex with a newly proposed adjustment of P-gain at the hip joint of the stance leg. We showed that the data of robot (normal subject model and cerebellum disease subject model) experiments had high similarities with the data of normal subjects and cerebellum disease subjects experiments carried out by Reisman et al. (2005) and Morton and Bastian (2006) in ratios and patterns. We also showed that P-gain at the hip joint of the stance leg was the control parameter of adaptation for symmetric gaits in splitbelt walking and P-gain adjustment corresponded to muscle stiffness adjustment by the cerebellum. Consequently, we successfully proposed the gait adaptation model in human splitbelt treadmill walking and confirmed the validity of our hypotheses and the proposed model using the biped robot.
AAU-BOT1: A Platform for Studying Dynamic, Life-Like Walking
Authors: Svendsen Mads Sølver , Helbo Jan , Hansen Michael Rygaard , Popovic Dejan B. , Stoustrup Jakob , Pedersen Mikkel Melters
Published: March 2015

This paper describes the development of the humanoid robot AAU-BOT1. The purpose of the robot is to investigate human-like walking and in this connection, test prosthetic limbs. AAU-BOT1 has been designed with modularity in mind making it possible to replace, e.g. the lower leg to test transfemoral or transtibial prosthesis or orthosis. Recorded motion data from a male test person, along with approximated inertial and mass properties, were used to determine necessary joint torques in human walking which was used as design parameters for the robot. The robot has 19 degrees of freedom (DoF), 17 actuated and 2 unactuated acting as passive toe joints. The project was granted 60,000 Euro, and to keep development costs below this, the development and instrumentation was carried out by three groups of master students from the Department of Mechanical Engineering (ME) and the Department of Electronic Systems at Aalborg University and supported by the Department of Health Sciences and Technology (HST). To further reduce the cost, the robot uses off-the-shelf hardware which also reduced the time from idea to practical implementation. The result is a low-cost humanoid robot fully assembled and equipped with sensors ready to take its first steps.
New Joint Design to Create a More Natural and Efficient Biped
Authors: Gini Giuseppina , Scarfogliero Umberto , Folgheraiter Michele
Published: March 2015

This paper presents a human-oriented approach to design the mechanical architecture and the joint controller for a biped robot. Starting from the analysis of the human lower limbs, we figured out which features of the human legs are fundamental for a correct walking motion, and can be adopted in the mechanical design of a humanoid robot. We focus here on the knee, designed as a compliant human-like knee instead of a classical pin-joint, and on the foot, characterised by the mobility and lightness of the human foot. We implemented an elastic actuator, with a simple position control paradigm that sets the joint stiffness in real time, and developed the basic controller. Results in simulation are discussed. In our approach the robot gains in adaptability and energetic efficiency, which are the most challenging issues for a biped robot.
Analysis of the Human Interaction with a Wearable Lower-Limb Exoskeleton
Authors: Moreno Juan C. , Brunetti Fernando , Navarro Enrique , Forner-Cordero Arturo , Pons José L.
Published: March 2015

The design of a wearable robotic exoskeleton needs to consider the interaction, either physical or cognitive, between the human user and the robotic device. This paper presents a method to analyse the interaction between the human user and a unilateral, wearable lower-limb exoskeleton. The lower-limb exoskeleton function was to compensate for muscle weakness around the knee joint. It is shown that the cognitive interaction is bidirectional; on the one hand, the robot gathered information from the sensors in order to detect human actions, such as the gait phases, but the subjects also modified their gait patterns to obtain the desired responses from the exoskeleton. The results of the two-phase evaluation of learning with healthy subjects and experiments with a patient case are presented, regarding the analysis of the interaction, assessed in terms of kinematics, kinetics and/or muscle recruitment. Human-driven response of the exoskeleton after training revealed the improvements in the use of the device, while particular modifications of motion patterns were observed in healthy subjects. Also, endurance (mechanical) tests provided criteria to perform experiments with one post-polio patient. The results with the post-polio patient demonstrate the feasibility of providing gait compensation by means of the presented wearable exoskeleton, designed with a testing procedure that involves the human users to assess the human-robot interaction.
Biology-Inspired Robust Dive Plane Control of Non-Linear AUV Using Pectoral-Like Fins
Authors: Ramasamy Subramanian , Singh Sahjendra N.
Published: March 2015

The development of a control system for the dive plane control of non-linear biorobotic autonomous underwater vehicles, equipped with pectoral-like fins, is the subject of this paper. Marine animals use pectoral fins for swimming smoothly. The fins are assumed to be oscillating with a combined pitch and heave motion and therefore produce unsteady control forces. The objective is to control the depth of the vehicle. The mean angle of pitch motion of the fin is used as a control variable. A computational-fluid-dynamics-based parameterisation of the fin forces is used for control system design. A robust servo regulator for the control of the depth of the vehicle, based on the non-linear internal model principle, is derived. For the control law derivation, an exosystem of third order is introduced, and the non-linear time-varying biorobotic autonomous underwater vehicle model, including the fin forces, is represented as a non-linear autonomous system in an extended state space. The control system includes the internal model of ak-fold exosystem, wherekis a positive integer chosen by the designer. It is shown that in the closed-loop system, all the harmonic components of order up tokof the tracking error are suppressed. Simulation results are presented which show that the servo regulator accomplishes accurate depth control despite uncertainties in the model parameters.
Impact of a Chest Support on Lower Back Muscles Activity During Forward Bending
Authors: Albayrak Armaĝan , Goossens Richard H. M. , Snijders Chris J. , de Ridder Huib , Kazemier Geert
Published: March 2015

The present study is based on previous research on the poor body posture of surgeons and their experienced discomfort during surgical procedures. Since surgeons have head-bent and back-bent posture during open surgical procedures, a chest support is a viable supporting principle. This support is meant to reduce lower back pain by minimising lower back muscle activity. The aim of this study is to investigate the impact of a chest support on lower back muscle activity during forward bending and to establish a possible relation between supporting force and the kind of balancing strategy a person adopts. Use of the chest support shows a significant reduction of muscle activity in the lower back and leg muscles. Within the participants three user groups are identified as “sceptical users”, “non-trusters” and “fully trusters”, each following a different balancing strategy. Since there are different kinds of users, the designed body support should offer the possibility for altering the posture and should not constrain the user to take a certain body posture.
Biomechanical Assessment of Reaching Movements in Post-Stroke Patients During a Robot-Aided Rehabilitation
Authors: Mazzoleni S. , Posteraro F. , Filippi M. , Forte F. , Micera S. , Dario P. , Carrozza M. C.
Published: March 2015

The main goal of this paper is to describe a method for the assessment of the motor performance in post-stroke subjects who have been undergone a robot-aided upper limb rehabilitation treatment. The motivation for adopting such methodology relies on the need of quantitative methods for the evaluation of the effects of robot-aided rehabilitation treatments, which assumes great importance from the clinical point of view. The method is based on the analysis of biomechanical parameters computed from force data recorded during the execution of planar reaching movements. Data from 17 chronic post-stroke patients and 5 healthy subjects were analysed. The results show the effectiveness of the proposed method, which can contribute to quantitatively evaluate the effects of a robot-mediated therapy on the upper limb of chronic post-stroke subjects.
Secure Microprocessor-Controlled Prosthetic Leg for Elderly Amputees: Preliminary Results
Authors: Krut S. , Coste Ch. Azevedo , Chabloz P.
Published: March 2015

We introduce a new prosthetic leg design, adapted to elderly trans-femoral amputees. Technical progress in prosthesis design mainly concerns active individuals. An important number of elderly amputees are not very mobile, tire easily, present reduced muscle strength, and have difficulties managing their balance. Therefore, the needs and characteristics of this specific population are very different from those of younger ones and the prosthetic solutions are not adapted. Our artificial knee has been designed to fulfill the specific requirements of this population in terms of capabilities, transfer assistance, security, intuitiveness, simplicity of use, and types of physical activity to be performed. We particularly focused our efforts on ensuring safe and secure stand-to-sit transfers. We developed an approach to control the different states of the prosthetic joint (blocked, free, resistant), associated with different physical activities. Amputee posture and motion are observed through a single multi-axis force sensor embedded in the prosthesis. The patient behaves naturally, while the controller analyses his movements in order to detect his intention to sit down. The detection algorithm is based on a reference pattern, calibrated individually, to which the sensor data are compared, and submitted to a set of tests allowing the discrimination of the intention to sit down from other activities. Preliminary validation of the system has been performed in order to verify the applicability of the prosthesis to different tasks: walking, standing, sitting down, standing up, picking up an object from a chair, slope and stair climbing.
In vivoUltrasonographic Evaluation of Patellar Tendon Stiffness after Anterior Cruciate Ligament Reconstruction with Patellar Tendon Autograft
Authors: Liu Hsin-Yi , Blackburn Troy , Padua Darin , Creighton R. Alexander , Weinhold Paul
Published: March 2015

Background:Tendon mechanical properties have been used to evaluate the effects of therapies on the healing of animal tendons, but these measures have not been convenient to record in vivo in humans due to their invasive nature. The aims of this study were to assess the capability of an ultrasonography technique to track the change in stiffness of the healing human patellar tendon and to assess the correlation between stiffness parameters and clinical recovery measurements.

Method:Ten subjects undergoing anterior cruciate ligament reconstruction with a patellar tendon autograft were recruited for the study as well as 10 healthy control subjects. The surgical tendons' mechanical properties were evaluated at 2 and 6 months after surgery with a two-scan ultrasonography technique. A paired sign-rank test was performed to compare the change in biomechanical parameters and clinical recovery measurements across time between surgical and control groups.

Results:Tendon stiffness of the surgical group increased from ~71% to ~94% when compared to the stiffness of the contralateral tendons at the first visit; however, the difference was not significant (P= 0.18). Significant improvements were shown in all the clinical recovery outcomes. Poor correlation was found between the clinical recovery measurements and tendon stiffness.

Conclusions:No significant change in patellar tendon stiffness with healing was detected over the 2–6 month period after surgery, suggesting the tendon stiffness recovery in humans proceeds more slowly than other clinical measures.
Development of an Active Ankle Foot Orthosis to Prevent Foot Drop and Toe Drag in Hemiplegic Patients: A Preliminary Study
Authors: Kim Jungyoon , Hwang Sungjae , Sohn Ryanghee , Lee Younghee , Kim Youngho
Published: March 2015

We developed an active ankle-foot orthosis (AAFO) that controls dorsiflexion/plantarflexion of the ankle joint to prevent foot drop and toe drag during hemiplegic walking. To prevent foot slap after initial contact, the ankle joint must remain active to minimize forefoot collision against the ground. During late stance, the ankle joint must also remain active to provide toe clearance and to aid with push-off. We implemented a series elastic actuator in our AAFO to induce ankle dorsiflexion/plantarflexion. The activator was controlled by signals from force sensing register (FSR) sensors that detected gait events. Three dimensional gait analyses were performed for three hemiplegic patients under three different gait conditions: gait without AFO (NAFO), gait with a conventional hinged AFO that did not control the ankle joint (HAFO), and gait with the newly-developed AFO (AAFO). Our results demonstrate that our newly-developed AAFO not only prevents foot drop by inducing plantarflexion during loading response, but also prevents toe drag by facilitating plantarflexion during pre-swing and dorsiflexion during swing phase, leading to improvement in most temporal-spatial parameters. However, only three hemiplegic patients were included in this gait analysis. Studies including more subjects will be required to evaluate the functionality of our newly developed AAFO.
Mechanical Impedance Control in the Human Arm While Manually Transporting an Open-Top Fluid Filled Dish
Authors: Roth Navit , Seliktar Rami , Mizrahi Joseph
Published: March 2015

The present study deals with stabilizing aspects of a hand-held dish filled with liquid while walking steadily. This is an attempt to decipher the neuro-muscular strategies employed and the mechanical responses of the arm during certain tasks of manual materials handling. The experimental configuration included a cup and the test-subject’s hand as an ‘end-effector’ of a serial three-link system representing the upper limb. These links are connected together by the wrist, elbow and shoulder joints. The tested subjects walked at constant speed on a treadmill while aiming to minimize liquid spillage from the cup. The motion of the limb and shoulder girdle served as inputs to a model to reveal the impedance adjustments during the simultaneous control of grasping and walking under ordinary conditions, and when one of the joints is affected. A regressive function used to express stiffness, included first-order dependence on angle and on angular velocity. The function used for damping included first-order dependence on angular velocity. Redundancies in the numerical solution were eliminated using multicollinearity diagnostic algorithms. The results revealed that the wrist joint was found to have constant stiffness and damping and no regulation of these coefficients was necessary during gait. Both in the elbow and shoulder joints stiffness included a constant coefficient as well as an angular velocity-dependent coefficient. Although all tested subjects demonstrated ability to prevent spillage of liquid, there was a considerable variability among the results obtained, indicating that the compensatory mechanisms employed by each subject to regulate the mechanical impedance were subjective. These results can help in the optimization of manual materials handeling tasks in industrial settings as well as future design of prosthetic arms, robotic appliances and man machine interfacing devices.
Cognitive Optimization in Assistive Living System Development
Authors: Bowling Alan , Makedon Fillia
Published: March 2015

This paper presents an exploration of the characteristics and structure of a cognitive architecture for control of assisted living systems. The aspects of cognition considered are self-organization, communication, and inherited knowledge. A cognitive solution for a related problem, function optimization, is developed because of the complexity and size of the assistive living problem. Support for this approach stems from the artificial intelligence field where optimization is considered to be a critical aspect of cognition, and from the similarity between the performance metrics for the two problem domains. A search algorithm is developed using the bracketing and gradient methods as inherited knowledge. A key finding is that using a cognitive structure caused the search to display aspects of the characteristics, behavior, and performance of human cognition. In terms of performance, the cognitive search converges faster than either the bracketing or gradient searches alone, and its feasible problem set is larger than the intersection of their individual sets. Similarly, human cognition acts quickly and can address a large set of dissimilar problems. This gives confidence that the guidelines distilled from the development of the cognitive search can produce a similar level of performance when applied to an assistive living system. However, this paper does not address the details involved in actually implementing these guidelines on an assistive living system.
A Review of fMRI as a Tool for Enhancing Eeg-Based Brain-Machine Interfaces
Authors: Barrios Luis J. , del Castillo Maria D. , Serrano José I. , Pons José L.
Published: March 2015

Human-robot interaction has been going stronger and stronger, up to find a notorious level on brain-machines interfaces. This assistive technology offers a great hope for patients suffering severe neuromuscular disorders. Starting from the current limitations hindering its extensive application outside the research laboratories, this paper reviews findings and prospects on functional magnetic resonance imaging showing how fMRI can help to overcome those limitations, while playing a key role on improving the development of brain-machine interfaces based on electroencephalography. The different types of derived benefits for this interfaces, as well as the different kinds of impact on their components, are presented under a field classification that reveals the distinctive roles that fMRI can play on the present context. The review concludes that fMRI provides complementary knowledge of immediate application, and that a greater profit could be obtained from the own EEG signal by integrating both neuroimaging modalities.
Scattered Data Processing Approach Based on Optical Facial Motion Capture
Authors: Zhang Qiang , Liang Xiaoying , Wei Xiaopeng
Published: March 2015

In recent years, animation reconstruction of facial expressions has become a popular research field in computer science and motion capture-based facial expression reconstruction is now emerging in this field. Based on the facial motion data obtained using a passive optical motion capture system, we propose a scattered data processing approach, which aims to solve the common problems of missing data and noise. To recover missing data, given the nonlinear relationships among neighbors with the current missing marker, we propose an improved version of a previous method, where we use the motion of three muscles rather than one to recover the missing data. To reduce the noise, we initially apply preprocessing to eliminate impulsive noise, before our proposed three-order quasi-uniform B-spline-based fitting method is used to reduce the remaining noise. Our experiments showed that the principles that underlie this method are simple and straightforward, and it delivered acceptable precision during reconstruction.