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Mechanical Design (mechanical + design)
Selected AbstractsHydrogels for Soft MachinesADVANCED MATERIALS, Issue 7 2009Paul Calvert Abstract Hydrogels have applications in surgery and drug delivery, but are never considered alongside polymers and composites as materials for mechanical design. This is because synthetic hydrogels are in general very weak. In contrast, many biological gel composites, such as cartilage, are quite strong, and function as tough, shock-absorbing structural solids. The recent development of strong hydrogels suggests that it may be possible to design new families of strong gels that would allow the design of soft biomimetic machines, which have not previously been possible. [source] Experimental validation and field performance metrics of a hybrid mobile robot mechanismJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 3 2010Pinhas Ben-Tzvi This paper presents the experimental validation and field testing of a novel hybrid mobile robot (HMR) system using a complete physical prototype. The mobile robot system consists of a hybrid mechanism whereby the locomotion platform and manipulator arm are designed as one entity to support both locomotion and manipulation symbiotically and interchangeably. The mechanical design is briefly described along with the related control hardware architecture based on an embedded onboard wireless communication network between the robot's subsystems, including distributed onboard power using Li-ion batteries. The paper focuses on demonstrating through extensive experimental results the qualitative and quantitative field performance improvements of the mechanical design and how it significantly enhances mobile robot functionality in terms of the new operative locomotion and manipulation capabilities that it provides. In terms of traversing challenging obstacles, the robot was able to surmount cylindrical obstacles up to 0.6-m diameter; cross ditches with at least 0.635-m width; climb and descend step obstacles up to 0.7-m height; and climb and descend stairs of different materials (wood, metal, concrete, plastic plaster, etc.), different stair riser and run sizes, and inclinations up to 60 deg. The robot also demonstrated the ability to manipulate objects up to 61 kg before and after flipping over, including pushing capacity of up to 61 kg when lifting objects from underneath. The above-mentioned functions are critical in various challenging applications, such as search and rescue missions, military and police operations, and hazardous site inspections. © 2010 Wiley Periodicals, Inc. [source] Dynamic performance of the beam position monitor support at the SSRFJOURNAL OF SYNCHROTRON RADIATION, Issue 1 2009Xiao Wang Electron beam stability is very important for third-generation light sources, especially for the Shanghai Synchrotron Radiation Facility whose ground vibrations are much larger than those for other light sources. Beam position monitors (BPMs), used to monitor the position of the electron beam, require a greater stability than other mechanical structures. This paper concentrates on an investigation of the dynamic performance of the BPM support prototype. Modal and response analyses have been carried out by finite-element (FE) calculations and vibration measurements. Inconsistent results between calculation and measurement have motivated a change in the soft connections between the support and the ground from a ground bolt in the initial design to full grout. As a result the mechanical stability of the BPM support is greatly improved, showing an increase in the first eigenfrequency from 20.2,Hz to 50.2,Hz and a decrease in the ratio of the root-mean-square displacement (4,50,Hz) between the ground and the top of the support from 4.36 to 1.23 in the lateral direction. An example is given to show how FE analysis can guide the mechanical design and dynamic measurements (i.e. it is not just used as a verification method). Similar ideas can be applied to improve the stability of other mechanical structures. [source] Nanoindentation response of compound semiconductorsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2007E. Le Bourhis Abstract The paper reviews the nanoindentation behaviour of III-V semiconductors under concentrated load and its implication for optoelectronic-device design. We consider first, fundamental aspects involved into the mechanical resistance to contact loading of semiconductor single crystals (elastic-plastic transition, indentation strain, hardness-yield relationship). The paper then describes recent applicative studies aimed at improving the heterostructure quality used in optoelectronic applications and emphasizes the so-called mechanical design (alloying and compliant substructure). (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Modelling and application of the self-locking phenomenon in the context of a non-discrete impact clutchPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2005Tobias Welge-Luessen This paper describes an application of the self locking phenomenon in order to realize a non-discrete impact clutch. It is used to generate velocity jumps in an underactuated robot manipulator. Due to control reasons the impacts have to be made possible at arbitrary times, which calls for a non-discrete device. Different design alternatives are listed and a numerical simulation as well as a possible mechanical design of the self-locking mechanism are presented. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A robotic assistant for stereotactic neurosurgery on small animalsTHE INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY, Issue 4 2008L. Ramrath Abstract Background This work presents the development and performance analysis of a robotic system for stereotactic neurosurgery on small animals. The system is dedicated to the precise placement of probes in the small animal brain, thus providing an improved framework for brain research. Methods Based on an analysis of small animal stereotaxy, the mechanical design of the robotic system is presented. Details of the structure and mechanical components and a kinematic description are outlined. The calibration process of the system for arbitrary probes is described. To analyse the mechanical positioning accuracy of the system, a testbed is presented. Results Positioning performance results show that the system features a mean mechanical positioning accuracy of 32 µm and a mean positioning repeatability of 11 µm. Conclusion The system meets the requirements of targeting small functional areas within the brain of small animals and thus offers a new tool for small animal brain research. Copyright © 2008 John Wiley & Sons, Ltd. [source] Study of the Different Types of Actuators and Mechanisms for Upper Limb ProsthesesARTIFICIAL ORGANS, Issue 6 2003Vanderlei O. Del Cura Abstract: Research in the area of actuators and mechanisms has shown steadily growing technological advances in externally activated upper limb prostheses. From among the actuators, advances include the use of piezoelectric materials, special metal alloys, polymers, and new motor applications, while the advances in mechanisms include mechanical designs based on the anatomy of the human hand and improvements in the way these components are combined. These efforts are aimed at meeting the need for anthropomorphic and functional prosthetic devices that enable patients to carry out basic daily tasks more easily and reduce the rejection rate of prostheses. This article technically discusses the several types of actuators and mechanisms, listing their main characteristics, applications, and advantages and disadvantages, and the current state of research in the area of rehabilitation of upper limb functions through the use of active prostheses. Comparisons of these devices are made with regard to the main criteria of construction and operation required to achieve optimal prosthetic performance. [source] | |||||||||||||