Spherical wrist dimensional synthesis adapted for tool-guidance medical robots

The objective of this article is to present the dimensional synthesis of serial or parallel spherical wrists, an important step in the design process of medical robots. This step is carried out to obtain optimal dimensions of tool-guidance medical robots. In this goal, we have first studied the specifications of two robots with different medical applications: one for minimally invasive surgery and one for tele-echography examination. Then, we have established that the medical needs expressed by the doctor were very different but the specifications in robotic terms have a lot of common points (kinematics, workspace, bulkiness). Both types of robots need a mobility of three rotations around a fixed point (trocar incision or probe contact point on patient’s skin). So a spherical wrist structure is adapted to their needs. An important constraint related to medical applications is that the robot must be compact to not obstruct the robot environment (medical personnel or patient). We perform dimensional synthesis allowing determination of dimensions of the mechanism for a spherical wrist, serial and parallel for a tele-echography robot, and serial for the minimally invasive surgery robot. We used multi-criteria optimization methods minimising a cost function to obtain both good kinematic performance and compactness for the structure. The difficulty and the difference between the presented studies are in the choice of design criteria describing the performance and the constraints of the robot. These parameters must faithfully represent the specifications of the robot so that its performance can respond to the medical requirements. We show, here, the different methods used for the chosen kinematic structure and the medical application. These studies lead to prototypes which are validated by medical experiments. This process of dimensional synthesis will be applied to other medical applications with different sets of specified constraints

Optimal dimensional synthesis of force feedback lower arm exoskeletons

This paper presents multi-criteria design optimization of parallel mechanism based force feedback exoskeletons for human forearm and wrist. The optimized devices are aimed to be employed as a high fidelity haptic interfaces. Multiple design objectives are discussed and classified for the devices and the optimization problem to study the trade-offs between these criteria is formulated. Dimensional syntheses are performed for optimal global kinematic and dynamic performance, utilizing a Pareto front based framework, for two spherical parallel mechanisms that satisfy the ergonomic necessities of a human forearm and wrist. Two optimized mechanisms are compared and discussed in the light of multiple design criteria. Finally, kinematic structure and dimensions of an optimal exoskeleton are decided

Multiobjective Optimum Design of a 3-RRR Spherical Parallel Manipulator with Kinematic and Dynamic Dexterities

This paper deals with the kinematic synthesis problem of a 3-underlineRRR spherical parallel manipulator, based on the evaluation criteria of the kinematic, kinetostatic and dynamic performances of the manipulator. A multiobjective optimization problem is formulated to optimize the structural and geometric parameters of the spherical parallel manipulator. The proposed approach is illustrated with the optimum design of a special spherical parallel manipulator with unlimited rolling motion. The corresponding optimization problem aims to maximize the kinematic and dynamic dexterities over its regular shaped workspace

Parallel manipulators: practical applications and kinematic design criteria. Towards the modular reconfigurable robots

Post-PrintModern robotic manipulators play an essential role in industry, developing several tasks in an easy way, enhancing the accuracy of the final product and reducing the executing time. Also they can be found in other fields as aerospace industry, several medical applications, gaming industry, and so on. In particular, the parallel manipulators have acquired a great relevance in the last years. Indeed, many research activities and projects deal with the study and develop-ment of this type of robots. Nevertheless, usually, a bilateral communication between industry and research does not exist, even among the different existing research areas. This causes a lack of knowledge regarding works that have been carried out, the ones that are under devel-opment and the possible future investigations. Hence, once a specific field of knowledge has acquired a certain level of maturity, it is convenient to reflect its current state of the art. In this sense, the authors of this paper present a review of the different fields in which parallel ma-nipulators have a significant participation, and also the most active research topics in the anal-ysis and design of these robots. Besides, several contributions of the authors to this field are cited.The authors wish to acknowledge the financial support received from the Spanish Government through the "Ministerio de Economía y Competitividad" (Project DPI2015-67626-P (MINECO/FEDER, UE)), the financial support from the Uni-versity of the Basque Country (UPV/EHU) under the program UFI 11/29 and the support to the research group, through the project with ref. IT949-16, given by the "Departamento de Educación, Política Lingüística y Cultura" of the Regional Government of the Basque Country

Progress on the preparation of nanocrystalline apatites and surface characterization: Overview of fundamental and applied aspects

Nanocrystalline calcium phosphate apatites constitute the main inorganic part of hard tissues, and a growing focus is devoted to prepare synthetic analogs, so-called “biomimetic”, able to precisely mimic the morphological and physico-chemical features of biological apatite compounds. Both from fundamental and applied viewpoints, an accurate characterization of nanocrystalline apatites, including their peculiar surface features, and a deep knowledge of crystallization aspects are prerequisites to attempt understanding mineralization phenomena in vivo as well as for designing innovative bioactive materials that may then find applications in bone tissue engineering, either as self-supported scaffolds and fillers or in the form of coatings, but also in other domains such as drug delivery or else medical imaging. Also,interfacial phenomena are of prime importance for getting a better insight of biomineralization and for following the behavior of biomaterials in or close to their final conditions of use. In this view,both adsorption and ion exchange represent essential processes involving the surface of apatite nanocrystals, possibly doped with foreign elements or functionalized with organic molecules of interest. In this review paper, we will address these various points in details based on a large literature survey. We will also underline the fundamental physico-chemical and behavioral differences that exist between nanocrystalline apatites (whether of biological origin or their synthetic biomimetic analogs) and stoichiometric hydroxyapatite

Encapsulating and representing the knowledge on the evaluation of an engineering system

This paper proposes a cross-disciplinary methodology for a fundamental question in product development: How can the innovation patterns during the evolution of an engineering system (ES) be encapsulated, so that it can later be mined through data mining analysis methods? Reverse engineering answers the question of which components a developed engineering system consists of, and how the components interact to make the working product. TRIZ answers the question of which problem-solving principles can be, or have been employed in developing that system, in comparison to its earlier versions, or with respect to similar systems. While these two methodologies have been very popular, to the best of our knowledge, there does not yet exist a methodology that reverseengineers and encapsulates and represents the information regarding the complete product development process in abstract terms. This paper suggests such a methodology, that consists of mathematical formalism, graph visualization, and database representation. The proposed approach is demonstrated by analyzing the design and development process for a prototype wrist-rehabilitation robot

Using Singularities of Parallel Manipulators for Enhancing the Rigid-body Replacement Design Method of Compliant Mechanisms

International audienceThe rigid-body replacement method is often used when designing a compliant mechanism. The stiffness of the compliant mechanism, one of its main properties, is then highly dependent on the initial choice of a rigid-body architecture. In this paper, we propose to enhance the efficiency of the synthesis method by focusing on the architecture selection. This selection is done by considering the required mobilities and parallel manipulators in singularity to achieve them. Kinematic singularities of parallel structures are indeed advantageously used to propose compliant mechanisms with interesting stiffness properties. The approach is first illustrated by an example, the design of a one degree of freedom compliant architecture. Then the method is used to design a medical device where a compliant mechanism with three degrees of freedom is needed. The interest of the approach is outlined after application of the method

How toxic are gold nanoparticles? The state-of-the-art.

With the growing interest in biotechnological applications of gold nanoparticles and their effects exerted on the body, the possible toxicity is becoming an increasingly important issue. Numerous investigations carried out, in the last few years, under different experimental conditions, following different protocols, have produced in part conflicting results which have leaded to different views about the effective gold nanoparticle safety in human applications. This work is intended to provide an overview on the most recent experimental results in order to summarize the current state-of-the-art. However, rather than to present a comprehensive review of the available literature in this field, that, among other things, is really huge, we have selected some representative examples of both in vivo and in vitro investigations, with the aim of offering a scenario from which clearly emerges the need of an urgent and impelling standardization of the experimental protocols. To date, despite the great potential, the safety of gold nanoparticles is highly controversial and important concerns have been raised with the need to be properly addressed. Factors such as shape, size, surface charge, surface coating and surface functionalization are expected to influence interactions with biological systems at different extents, with different outcomes, as far as gold nanoparticle potentiality in biomedical applications is concerned. Moreover, despite the continuous attempt to establish a correlation between structure and interactions with biological systems, we are still far from assessing the toxicological profile of gold nanoparticles in an unquestionable manner. This review is intended to provide a contribution in this direction, offering some suggestions in order to reach the systematization of data over the most relevant physico-chemical parameters, which govern and control toxicity, at different cellular and organismal levels