Eres Söylemez

Transmission optimization of spatial 4-link mechanisms

Abstract The design of plane crank-and-rocker linkages with given rocker swing angle, corresponding crank rotation and optimum force transmission are well known problems in kinematic synthesis. This investigation is concerned with the transmission optimization of the skew crank-and-rocker linkage and the skew slider-crank mechanism. The algebraic loci of the moving joints are used to express the lengths of the moving links as a function of a single parameter, the optimum value of which is obtainable as a constrained minimization problem involving 1-parameter scanning. The results are presented in tables as well as in design charts.

Deployable space structures

Deployable structures are mobile assemblies which do not aim motion but to attain different configurations depending on the service requirements. These structures are widely used in space applications due to storage limitations of the launch vehicles. The large diversity of design alternatives should be evaluated in design of deployable parts of spacecrafts. This study aims to present design alternatives of antennas, masts and solar panels of space devices. Also use of spatial linkages in deployable structure designs is discussed.

Classical transmission-angle problem for slider–crank mechanisms

Abstract The classical transmission-angle problem for slider–crank mechanisms is the determination of the dimensions of planar slider–crank mechanisms with optimum transmission angle for given values of the slider stroke and corresponding crank rotation. In this study complex algebra is used to solve this classical problem. The solution is obtained as the root of a cubic equation within a defined range, which can be easily implemented on a computer.

Transmission optimization of right-angled four-bar mechanisms

Abstract Design of spatial four-bar mechanisms in which the skew crank axes are at right angles is investigated. Using an algebraic approach, the lengths of the moving links are expressed as functions of a single parameter. Transmission optimization of right-angled four-bar mechanisms can then be determined from the solution of a single parameter constrained optimization problem. When the motion is symmetric, mechanism proportions which yield constant force trasmission characteristics can be obtained.

Regular Polygonal and Regular Spherical Polyhedral Linkages Comprising Bennett Loops

In this study, assemblies of Bennett loops constructing regular polygonal linkages and regular polyhedral linkages are presented. The regular polyhedral linkages, necessarily, depend on spherical polyhedral shapes. Most of the resulting linkages have single degree of freedom, but there are exceptions such as a cubic linkage.

Using Computer Spreadsheets in Teaching Mechanisms

In this paper the use of widely available user friendly spreadsheet programs such, as, Microsoft® Excel in teaching mechanisms is explained and its advantages over off-the-shelf programs are shown. Instead of using specific costly programs for the analysis and synthesis of different mechanisms, the students are first thought certain features of Excel and later starting with the analysis of single loop mechanisms, the solution of more complex problems in the analysis and synthesis of mechanisms are attempted. The simulation of mechanisms can be achieved by using the Chart and control toolbox features of Excel. Students are able to prepare their own spreadsheets for the solution of different mechanism problems. In this article different examples using spreadsheet program will be explained and its benefits as an educational tool will be demonstrated.

Kinematic Design of a Reconfigurable Deployable Canopy

A reconfigurable and deployable mechanism is proposed for a canopy which can also be used as a tent or a semi-open structure. The proposed single degree-of-freedom mechanism has four assembly modes. The conditions for deployment and reconfiguration of the mechanism are derived. These conditions impose three equality and two inequality constraints on the 11 design parameters of the mechanism. A virtual model of the mechanism is constructed in Excel for design and simulation purposes. A computational case study is presented.

The generalized yale lock-a versatile logical element☆

Abstract The logical function and design has been described of a versatile, mechanical logical element, which may be regarded as a generalization of the Yale lock. It is a displacement-sensitive device, which can perform many logical functions involved in mechanical systems.

On the Accuracy Analyses of a Class of 2-DOF Planar Parallel Manipulators

This study is about the accuracy analysis of two degrees of freedom planar parallel manipulators consisting of five links (one of which is fixed) that are connected to each other with five revolute (R) or prismatic (P) joints. Among these manipulators, topologically RRRRR, PRRRP, RPRPR planar parallel manipulators are selected. Accuracy analysis is a common method to evaluate the performance of parallel manipulators. In this study, accuracy analysis of these planar parallel manipulators is presented by using local conditioning index and maximum positional error methods. For each of the manipulators, mathematical expressions for the local conditioning index and maximum positional errors are derived. These expressions are implemented using Matlab© environment and examples are presented to show the accuracy distributions over the workspace. The consistency between local conditioning index and maximum positional error is discussed.

Homohedral and Tangential Polyhedral Linkages

The study aims to devise means of obtaining polyhedral linkages for homothetic deployment of polyhedral shapes by embedding planar link groups in faces of the polyhedral shape of interest. The questions of which polyhedral shapes may be suitable for such a purpose and what are the compatibility conditions for spatially assembling planar link groups are addressed. Homohedral and tangential polyhedral shapes are found to be suitable for the task and some examples of linkages are worked out.