Michael A. Saliba

Neutron-induced peaks in Ge detectors from evaporation neutrons

Abstract We have studied the peak shapes at 596 and 691 keV resulting from fast neutron interactions inside germanium detectors. We have used neutrons from a 252 Cf source, as well as from the 28 Si(μ − , nv), and 209 Bi(π − , xn) reactions to compare the peaks and to check for a dependence of peak shape on the incoming neutron energy. In our investigation, no difference between these three measurements has been observed. In a comparison of these peak shapes with other studies, we found similar results to ours except for those measurements using monoenergetic neutrons in which a significant variation with neutron energy has been observed.

Design of a compact, dexterous robot hand with remotely located actuators and sensors

In this work, we report on our progress in the development of a new anthropomorphic robot hand at the University of Malta. Following a brief overview of the work carried out in our laboratory so far, we discuss in some detail and through a fresh perspective a number of important lessons that can be learned from the human hand, and that can be very useful in the development of an artificial hand that can ultimately match the human counterpart in the execution of many tasks. We present a new design for a robot hand with joint position and grasping force sensing, based on the specific approaches brought up in this discussion, and targeted to reproduce many of the capabilities of the human hand. In particular, all of the actuation and sensing devices of the hand are located remotely from the device, therefore facilitating the development of a compact and lightweight hand design. A prototype of the new hand has been constructed and is presented herein. Finally, we present the initial results of our analysis to demonstrate how the magnitude and location of grasping forces can be inferred from the sensor readings.

An innovative robotic gripper for grasping and handling research

A planar robotic gripper suitable for research in the grasping and handling of a wide variety of objects has been developed. The design has two fingers, four links, and two actuators but can be directly extended to more links while keeping the number of actuators unchanged. This robotic end effector exhibits two distinctive features. First, it utilizes a fewer number of actuators than it has degrees of freedom, thus providing quantifiable savings in weight, size, complexity and cost. Second, it is capable of conforming to different shapes and sizes of objects through autonomous, sequential switching of the actuator drives between links. The design, construction and research applications of the hand are described. Experimental results with the robotic hand show close agreement with computer simulations.<<ETX>>

TOWARDS THE RATIONALIZATION OF ANTHROPOMORPHIC ROBOT HAND DESIGN: EXTRACTING KNOWLEDGE FROM CONSTRAINED HUMAN MANUAL DEXTERITY TESTING

In this work, we take a new approach to the determination of the quantified contribution of various attributes of the human hand to its dexterity, with the aim of transposing this knowledge into supportive guidelines for the design of anthropomorphic robotic and prosthetic hands. We have carried out a number of standard dexterity tests on normal human subjects with various physical constraints applied to selected attributes of their hands, and have analyzed the results of the tests to extract knowledge on the quantified contribution of each attribute to overall manual dexterity. This knowledge is particularly significant in cases where it is important to optimize the trade-off between dexterity and complexity in the design of artificial hands. The data collection was made over 35 h of direct experimentation involving 40 volunteers during two separate runs, and the results represent empirically-derived upper limits on the achievable performance of humanoid robot hands having the specified deficiencies. We discuss the implications of our results in the context of a minimal anthropomorphic dexterous hand, which would incorporate the lowest possible number of degrees of freedom and other attributes while still retaining an acceptable level of dexterity. We end the paper with a suggestion on how the general approach presented herein could be extended to provide a platform for the quantification of the dexterity of anthropomorphic artificial hands.

A modular, reconfigurable end effector for the plastics industry

Purpose – The purpose of this paper is to address a problem that is commonly faced by manufacturing companies in the plastics industry, where large and different batches of freshly produced units need to be unloaded from the injection‐moulding machines and relocated, using automation.Design/methodology/approach – The new solution is reached through a formal design approach, including a function analysis, a product design specification, a quality function deployment exercise, the generation of a number of conceptual solutions, and concept evaluation using morphological charts, failure mode and effect analysis and a decision matrix.Findings – A single modular end effector that can be easily reconfigured for a large variety of moulds has been developed. The results are also extrapolated to more general applications where an end effector is required to carry out simultaneously several different but well‐defined functions in the presence of high variety.Research limitations/implications – The critical decision...

Undergraduate Mechatronics Research Case Study: Contributing towards a Dexterous Robot Hand:

The importance of implementing a strong project-based approach to undergraduate mechatronics education and the enhancement obtained through the introduction of a research aspect to these projects have been emphasized in the literature. This paper describes the immersion of final-year undergraduate mechanical engineering students into the research programme of the Department of Industrial and Manufacturing Engineering of the University of Malta, through supervised undergraduate projects that build upon each other from year to year, eventually leading to publications in the international research literature. We focus on the area of robot hands and present an extended project as a case study. We first describe briefly a selection of research-oriented undergraduate projects in this area carried out over the last decade. The paper then focuses on one particular project among those described, involving the development of an anthropomorphic robot hand with eight degrees of freedom that is based on observations of the attributes and the limitations of the human hand. The robot hand is intended to be used as a teleoperated slave device and a particular objective is to reduce its size and weight through the remote location of all of the actuators and sensors. The paper gives a detailed rationale for the design, followed by descriptions of the kinematic, mechanical, actuation, sensing and control systems of the constructed prototype. This is followed by a description of sensor calibration procedures and results. The paper concludes with a brief discussion of the significance of this work, addressing both the educational and research aspects, and of future directions to be taken.

Towards the development of a minimal anthropomorphic robot hand

Many robot hands in the literature try to achieve full kinematic anthropomorphism, and as such are often very complex and difficult/expensive to produce. This paper follows recent work that predicts that high dexterity can also be achieved through a minimal (reduced) anthropomorphic design. New experimental and simulation results that optimize grasping performance for a minimal hand are presented. A first prototype of the hand, incorporating the optimized kinematics as well as innovative endoskeletal mechanical and actuation architectures, has been designed. The robot hand prototype has been fabricated using fused deposition modelling technology, and is evaluated with respect to its grasping performance.

Addressing simplicity, dexterity and usability of compact, multi-degree-of-freedom mechatronic devices

Many modern multi-degree-of-freedom mechatronic devices are characterized by considerable and often severe size and weight constraints, and it is therefore desirable to address the design of such devices in a systematic and effective manner. The design evaluation and improvement technique being investigated in this work revolves around three desirable yet often conflicting attributes of devices of this type, being simplicity, dexterity and usability. Detailed qualitative definitions of these terms are proposed. Furthermore, a method that quantifies these design attributes in an arbitrary device of this type is presented. This method is aimed at providing objective measures of the strengths and weaknesses of the design, and the mathematical tool can assist designers and engineers in evaluating, comparing and improving device designs. Towards the end of the paper the methodology is applied to a case study to augment the design process of a minimal anthropomorphic robot hand.

The university of Malta minimal anthropomorphic robot (UM-MAR) Hand II

A minimal anthropomorphic robot hand is under development in the Faculty of Engineering at the University of Malta. The basic design is based on previous work in the faculty that has shown quantitatively that acceptable dexterity can potentially be achieved using a ten joint, eight degree-of-freedom hand that incorporates a thumb, two fingers, and effective touch sensing and hand control systems. The second test version of this hand, UM-MAR Hand II, has been built and is presented in this work. The approach taken in the development of this second prototype focusses on enhancing three fundamental and often conflicting attributes of compact multi-degree-of-freedom systems, identified as the simplicity, dexterity and usability of the device. In particular, extensive simulation work is carried out to optimize the fixed Denavit-Hartenberg parameters of the hand, as well as the joint ranges, in order to achieve human-like grasping dexterity with the reduced kinematic configuration. The design, development, construction and early evaluation of the UM-MAR Hand II are described in detail.

Experimental extraction of tactile sensor specifications for a minimal anthropomorphic robot hand

In this work a new approach is taken towards determining the quantified contribution of tactile acuity to human manual dexterity, and the implications of this approach when applied to the development of artificial fingertip touch sensors for humanoid robots or for prosthetic hands. The interdependence between several dimensions of both tactile acuity and dexterity is investigated. An experimental study was performed on a carefully chosen sample of 30 human subjects, with data acquisition taking place over a total period of 35 hours of testing in a controlled environment. The data were analyzed to extract minimum levels of tactile acuity that would result in manual dexterity performance at 80% of normal. These extracted levels are interpreted to represent minimum specifications for the design of an artificial tactile sensor that would endow a robot hand with acceptable dexterity, and are used in a case study to drive the conceptual design process for a new tactile sensor based on quantum tunneling composite material.