Nicola Pio Belfiore

Automatic sketching of planar kinematic chains

Abstract In this paper an original method for the fully automatic sketching of planar kinematic chains is described. This procedure may ease the interpretation of the results obtained during the enumeration of complex multi-loop kinematic chains. The designer is supplied with a graphical interface useful to better understand and topological properties of the kinematic chain generated, by a confortable visual inspection. The sketch of a kinematic chain is obtained by first mapping the graph in the plane and then sketching its line-graph, after deletation of extraneous edges. The graph is embedded of the graph directly leads to the deletion of the extraneous edges of the line-graph. Likewise, a straightforward original procedure converts the embedded edges of the graph into embedded vertices of the line-graph. A fully automatic drawing of the complete atlas of 1 d.o.f. planar kinematic chains with eight and ten links was obtained without any occurrence of crossing links. Finally, several examples are illustrated and some further developments discussed.

An atlas of linkage-type robotic grippers

In this paper an atlas of 64 linkage-type grippers is presented. For each mechanism one of the possible functional schematic is provided for a better understanding of its kinematic properties. Some of the linkages herein depicted are believed to be novel. The atlas should be helpful to designers in the field of robotics. Graph theory is involved, as far as the concepts of enumeration and isomorphism. The enumeration methodology adopted is described in detail and an extension of the concept of isomorphism to the class of actuated mechanisms briefly recalled.

An Atlas of Remote Actuated Bevel Gear Wrist Mechanisms of up to Nine Links

An atlas of topological and functional representations of bevel gear-type basic robotic wrists of up to nine links with all the actuators connected to the frame link is presented. Each wrist mechanism is depicted by means of a canonical diagram that can be adopted as a schematic model for the final constructive embodiment. The corresponding graphic representation is also shown, together with a reference number that classifies the structure through the concepts of nonfractionated degree of freedom and equivalent-open-loop chain.An atlas of topological and functional representations of bevel gear-type basic robotic wrists of up to nine links with all the actuators connected to the frame link is presented. Each wrist mechanism is depicted by means of a canonical diagram that can be adopted as a schematic model for the final constructive embodiment. The corresponding graphic representation is also shown, together with a reference number that classifies the structure through the concepts of nonfractionated degree of freedom and equivalent-open-loop chain.

MEMS-Based Conjugate Surfaces Flexure Hinge

This paper presents a new concept flexure hinge for MEMS applications and reveals how to design, construct, and experimentally test. This hinge combines a curved beam, as a flexible element, and a pair of conjugate surfaces, whose contact depends on load conditions. The geometry is conceived in such a way that minimum stress conditions are maintained within the flexible beam. A comparison of the new design with the other kind of revolute and flexible joints is presented. Then, the static behavior of the hinge is analyzed by means of a theoretical approach, based on continuum mechanics, and the results are compared to those obtained by means of finite element analysis (FEA) simulation. A silicon hinge prototype is also presented and the construction process, based on single step lithography and reactive ion etching (RIE) technology, is discussed. Finally, a crucial in–SEM experiment is performed and the experimental results are interpreted through the theoretical models.

Connectivity and Redundancy in Spatial Robots

In this paper, the concepts of connectivity, degrees of control, and redundancy are revisited from a pure topological viewpoint and then applied to robotics. The redundancy matrix is defined to provide designers with a useful support in the first conceptual phase of the project of a new manipulator. An algorithm for building the connectivity and the redundancy matrices for a large class of manipulators is derived and implemented in an algebraic manipulation programming language. Based on some results borrowed from graph theory, the procedure can be used to study open-loop, closed-loop, and hybrid kinematic chains. In particular, it is shown how the biconnected components of the graph corresponding to the manipulator under analysis have to be detected for a correct computation of connectivity and redundancy. Furthermore, the study of the connectivity and of the degrees of control led to the development of a full mobility test that automatically detects the type of mobility of any given robot: total, partial, or fractionated. One of the presented sample cases offers the opportunity to discover some differences between the connectivity matrix obtained by means of the new algorithm and that presented, on the same kinematic chain, in a previous one.

Development of Micro-Grippers for Tissue and Cell Manipulation with Direct Morphological Comparison

Although tissue and cell manipulation nowadays is a common task in biomedical analysis, there are still many different ways to accomplish it, most of which are still not sufficiently general, inexpensive, accurate, efficient or effective. Several problems arise both for in vivo or in vitro analysis, such as the maximum overall size of the device and the gripper jaws (like in minimally-invasive open biopsy) or very limited manipulating capability, degrees of freedom or dexterity (like in tissues or cell-handling operations). This paper presents a new approach to tissue and cell manipulation, which employs a conceptually new conjugate surfaces flexure hinge (CSFH) silicon MEMS-based technology micro-gripper that solves most of the above-mentioned problems. The article describes all of the phases of the development, including topology conception, structural design, simulation, construction, actuation testing and in vitro observation. The latter phase deals with the assessment of the function capability, which consists of taking a series of in vitro images by optical microscopy. They offer a direct morphological comparison between the gripper and a variety of tissues.

Fabrication of Novel MEMS Microgrippers by Deep Reactive Ion Etching With Metal Hard Mask

The fabrication of a novel class of microgrippers is demonstrated by means of bulk microelectromechanical systems (MEMS) technology using silicon on insulator wafer substrates and deep reactive ion etching. Hard masking is implemented to maximize the selectivity of the bulk etching using sputtered aluminum and aluminum–titanium thin films. The micro-roughness problem related to the use of metal mask is addressed by testing different mask combinations and etching parameters. The O2 flow, SF6 pressure, wafer temperature, and bias power are examined, and the effect of each parameter on micro-masking is assessed. Sidewall damage associated with the use of a metal mask is eliminated by interposing a dielectric layer between silicon substrate and metal mask. Dedicated comb-drive anchors are implemented to etch safely both silicon sides down to the buried oxide, and to preserve the wafer integrity until the final wet release of the completed structures. A first set of complete devices is realized and tested under electrical actuation. [2017-0039]

The development of a MEMS/NEMS-based 3 D.O.F. compliant micro robot

Microrobots are used nowadays in several fields of application, specially in mini invasive surgery. However, they are rather difficult to be constructed, and the traditional micro machining tools are not adequate yet to built the smaller parts. The construction of the microrobots is even harder if more than one D.O.F. are required for the mechanism, because these systems are more complicated. This paper deals with the development of a 3 D.O.F. planar micro platform with remote system of actuation. The new approach of design and manufacturing is based on two innovative solutions: a) the adoption of the technologies used to built MEMS, Micro Electro Mechanical Systems; b) the introduction of new flexural hinge to develop compliant micro mechanisms. The new concept of flexural hinge is described in the paper, also from a theoretical point of view. Several example of possible structures are proposed and analyzed, together with their remote wire actuation systems. Finite Element Analysis (FEA) has been also adopted to analyze the system performance under small deformations. The principle of fabrication is, then, described. The process consists of a sequence of single steps which have allowed to achieved an overall maximum size down to 3–4 mm and the minimum thickness of the smaller components down to 50µm.

Distributed Databases for the development of Mechanisms Topology

Abstract In this paper different types of data structures for database modeling are reviewed in order to suggest the one which most suits the needs of a database management system dedicated to the study of the mechanical systems. Topology is proposed as the classification criterion, this inspiration being due to the separation of the concepts of structure and function, as proposed for the first time by Freudenstein and Maki [Environ. Planning B 6 (1979) 375–391]. An example of a local database is herein presented and, finally, the adopted codes are briefly commented upon which, on the base of the evaluation of the power of the adjacency matrices, identify the kinematic chains (KCs) and mechanisms.

A brief note on the concept of planarity for kinematic chains

In this note the concept of planarity is briefly reviewed with the aim of suggesting a unified interpretation of this word as an attribute of the concept of kinematic chain. The lack of a correct and unambiguous meaning of the concept of planar kinematic chain may cause serious misunderstandings nowadays, as in the reported example.