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Several different setups may be introduced as candidate options in a process plan for manufacturing a workpiece. It is required to employ an efficient optimization method to decide on the most competent setups. In the existing methods for optimizing the process plan, the main problem is the large search space size, which reduces the speed of finding the optimal solution or causes getting caught in the local minima. To remedy this problem, an optimization method has been developed in the present study based on a combined approach by employing the simulated annealing and the permutation-based setup planning algorithms. A new cost function has been introduced in this approach. The proposed method also has other advantages and capabilities in line with minimizing the manufacturing error and obtaining a uniquely optimized solution. A comparative study has been conducted to illustrate the capability of the proposed method. The results indicate that the rate of convergence to the optimal solution increases and the performance in finding the solution improves by using the method described in this paper. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to study the workspace and dexterity of a microhexapod which is a 6-degrees of freedom (DOF) parallel compliant manipulator, and also to investigate its dimensional synthesis to maximize the workspace and the global dexterity index at the same time. Microassembly is so essential in the current industry for manufacturing complicated structures. Most of the micromanipulators suffer from their restricted workspace because of using flexure joints compared to the conventional ones. In addition, the controllability of micromanipulators inside the whole workspace is very vital. Thus, it is very important to select the design parameters in a way that not only maximize the workspace but also its global dexterity index. Design/methodology/approach – Microassembly is so essential in the current industry for manufacturing complicated structures. Most of the micromanipulators suffer from their restricted workspace because of using flexure joints compared to the conventional ones. In addition, the controllability of micromanipulators inside the whole workspace is very vital. Thus, it is very important to select the design parameters in a way that not only maximize the workspace but also its global dexterity index. Findings – It has been shown that the proposed procedure for the workspace calculation can considerably speed the required calculations. The optimization results show that a converged-diverged configuration of pods and an increase in the difference between the moving and the stationary platforms’ radii cause the global dexterity index to increase and the workspace to decrease. Originality/value – The proposed algorithm for the workspace analysis is very important, especially when it is an objective function of an optimization problem based on the search method. In addition, using screw theory can simply construct the homogeneous Jacobian matrix. The proposed methodology can be used for any other micromanipulator. [ABSTRACT FROM AUTHOR]

Parallel mechanisms have found new applications in machine tool’s as the end effector carrying the spindle or used as the table of the machine. Investigations on the dynamics and especially the vibration behavior of these mechanisms are in the initial stage. The authors developed a vibration model for the hexapod table of milling machines and machining centers and derived the relevant explicit equations. The eigenvalue problem of the upper platform of hexapod was solved to obtain the natural frequencies of the platform. The results have been verified with FEM simulation. The distinguishing features of the hexapod tables from the view point of dynamic behavior have also been concluded. [ABSTRACT FROM AUTHOR]