781 research outputs found
Conversazione con Marco Petreschi
No full textColloquio sulle idee e sulle opere architettoniche di Marco Petreschi, all'interno d'una collana che comprende volumi dedicati a Portoghesi, Purini e Fuksas
An Atlas of Remote Actuated Bevel-Gear Type Wrist Mechanisms of up to 9 Links
No full textAn 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
Micromanipulation: A Challenge for Actuation
No full textManipulating micro objects has become an important task in several applications. Actuation is a crucial aspect of micromanipulation because there are physical restrictions which affect actuators’ performances at the micro or nano scale. One way of getting rid of these limitations is the use of an appropriate mechanical structure which enhances the elasticity of the material or provides mechanical advantage. This Special Issue of Actuators, which is dedicated to micromanipulation, offers a contribution to the development of some promising methods to actuate a microsystem for micromanipulation
On the numerical computation of generalized burmester points
No full textThis note describes a procedure for plane higher-curvature path analysis and synthesis. All coefficients have been written in terms of elementary instantaneous invariants. This facilitates the numerical computation of Generalized Burmester Points for a moving link of a planar mechanism in a non-symmetric position. FORTRAN subroutines have been written and a numerical example is provided
An atlas of linkage-type robotic grippers
No full textIn 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
On Crossley's contribution to the development of graph based algorithms for the analysis of mechanisms and gear trains
No full textThis paper celebrates a particular branch of Crossley's early work dedicated to Mechanism Science, which deals with a rigorous introduction of Graph Theory to the study of some fundamental and intrinsic properties of kinematic chains and mechanisms. Although such idea gave its main outcome in Type and Number Synthesis (which has been much better and extensively described in another paper of the present special issue) some other intriguing side effects appeared, later in Mechanism Science, which yielded several results, and are still in the center of research and industrial world interest, such as, to name but a few, the automatic generation of the equations governing kinematic, static force and dynamic analysis of mechanisms and geared trains, the power flow analysis, the computation of the efficiency and, finally, the never fully explored structure-to-function mapping, which the present contribution points out to be still a challenge in the field
Kinematic Design and Optimization of Automatic Drive Transmissions
No full textThe paper describes a systematic approach to the dimensional synthesis of multiple-speed automatic transmissions for prescribed velocity ratios and minimum circulating power. For a given displacement graph, the method starts exploiting all the feasible clutching sequences and then computes the gear ratios to achieve the prescribed input-output velocity ratios. In order to detect the gear drive with the lowest circulating power, a power flow analysis has been completed for each component of the solution set. A singular feature of this work is the simultaneous optimization of kinematic structure, gear ratios and clutching sequence to achieve minimum circulating power. A numerical example details all the phases of the suggested method
On Crossley's contribution to the development of graph based algorithms for the analysis of mechanisms and gear trains
No full textThis paper celebrates a particular branch of Crossley's early work dedicated to Mechanism Science, which deals with a rigorous introduction of Graph Theory to the study of some fundamental and intrinsic properties of kinematic chains and mechanisms. Although such idea gave its main outcome in Type and Number Synthesis (which has been much better and extensively described in another paper of the present special issue) some other intriguing side effects appeared, later in Mechanism Science, which yielded several results, and are still in the center of research and industrial world interest, such as, to name but a few, the automatic generation of the equations governing kinematic, static force and dynamic analysis of mechanisms and geared trains, the power flow analysis, the computation of the efficiency and, finally, the never fully explored structure-to-function mapping, which the present contribution points out to be still a challenge in the field
Automatic sketching of planar kinematic chains
No full textIn 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. © 1993
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