INTERNATIONAL JOURNAL OF ADVANCED DESIGN AND MANUFACTURING TECHNOLOGY
Year:2010 | Volume:3 | Issue:2 (10) (AN INTERNATIONAL QUARTERLY)|Papers Count:8

This paper presents optimal control method to path planning of mobile robots with flexible joints. Dynamic equations are derived and additional kinematic constraints are used to solve the extra Dofs arose from base mobility. Then with modeling the elasticity at each joint as a linear torsinal spring, the set of equations are formed. The Hamiltonian function is formed and the necessary conditions for optimality are derived from the Pontryagin's minimum principle. The obtained equations established a two point boundary value problem solved by numerical techniques. This problem is known to be complex in particular when combined motion of the base and manipulator, non-holonomic constraint of base and non-linear and complicated dynamic equations as a result of flexible nature of joints are taken into account. The study emphasizes on modeling of the complete optimal control problem by remaining all nonlinear state and costate variables as well as control constraints to establish accompanying boundary value problem. Another advantage of this method is obtaining various optimal trajectories with different characteristics by changing the penalty matrices values which enables the designer to choose the best trajectory. A mobile flexible joint manipulator is studied to verify the feasibility of the proposed approach.

Recently, as the result of development in modern imaging, computerized three dimensional data processing and advanced engineering techniques, a prosthesis that match the skeletal anatomy can be accurately designed using computer aided design (CAD) where the physical model of prosthesis or skull replica can be produced through rapid prototyping (RP), rapid tooling (RT), and computer aided manufacturing (CAM) technology. This paper aims to describe CAD, CAM, RP systems and technologies for design and fabrication of custom-made hip prostheses. A novel methodology based on RP technology is applied to design and manufactures custom-made hip prostheses. Results show that the RP models provide an accurate and useful tool for preoperative, surgical simulation and fabrication of such prostheses. Concerning the disadvantages such as time and cost for the hip prostheses design and need for surgical robot to perform the bone resection and preparing proper femoral canal, RP technologies fabricate the custom-made prostheses quickly, accurately and economically. 

Shape error due to elastic recovery of formed part in unloading known as springback, is one of the most important problems of tool design in sheet metal forming processes. Many researches have been performed for proposing an efficient method to decrease or compensate springback error in sheet forming processes. These methods are usually based on iterative finite element algorithms. In this paper an analytical approach is presented for one step modification of the tooling shape in channel forming process to compensate the springback error. With the help of this approach, the optimum die shape for producing the target shape can be obtained in a few seconds. The algorithm of spring back compensation by inverse FE modelling is also presented. By balancing the contact forces in this algorithm, symmetric and asymmetric sheet forming processes can be analyzed. The results of the analytical approach coincide with those of FE approach. The accuracy of the obtained results is verified by the experimental results. Asymmetric channel forming tests are performed on steel and aluminum sheets. The test results coincide to the analytical results with high precision. 

Several approaches are available to reduce pulsating torque components in permanent magnet motors. One of the known techniques is stator tooth shape modifications. This paper presents an integrated algorithm applicable for tooth shape optimization of permanent magnet motors. This method focuses on the reduced basis technique, finite element analysis and Taguchi method and is conducted on tooth shape optimization of a 3-phases radial flux PMSM motor.

Zn-Co electrodeposits have attracted interest because of their significantly higher corrosion resistance in comparison with pure zinc. In this research the influence of bath temperature and electrolyte’s Co2+ concentration on the morphology and composition of the Zn-Co coatings, electrodeposited on an AISI1018 steel substrate from a weakly alkaline glycine solutions, has been studied. SEM and EDS analysis were used to study surface morphology and composition of Zn-Co alloy coatings. It was shown that by increasing the bath temperature and Co2+ concentration in electrolyte, the cobalt concentration in the coating was increased. By increasing the cobalt concentration in the bath favoring the formation of smaller grains; however further increase of cobalt in the bath resulted in coarsens the morphology of the coating.

A truly meshless local Petrov-Galerkin (MLPG) method is developed for solving 3D elasto-static problems. Using the general MLPG concept, this method is derived through the local weak forms of the equilibrium equations, by using test functions, namely, the Heaviside function. The moving least squares (MLS) are chosen to construct the shape functions, for the MLPG method. The penalty approximation is used to impose essential boundary condition. Several numerical examples are included to demonstrate that the present method is very promising for solving the elastic problems.

Rapid thermal processing (RTP) has become a key technology for semiconductor device manufacturing in a variety of applications, such as thermal oxidation, annealing, and thin-film growth. Hence, understanding the radiative properties of silicon and other relevant materials is essential for the analysis of the thermal transport processes. We have analyzed and calculated the spectral, directional and temperature dependency of radiative properties of a three layers material using transfer-matrix method. In the present work empirical expressions for calculating the optical constants of materials are carefully selected. The studied examples using silicon wafer and either silicon dioxide or silicon nitride coating demonstrate the strong influence of coating and coating thickness on the radiative properties. This study helps to gain a better understanding of the radiative properties of semitransparent wafers with different coatings and will have an impact not only on semiconductor processing but also on thin film solar cells. Results showed that silicon dioxide coating has higher reflectance than silicon nitride coating for visible wavelengths. Therefore coatings act as wavelength selective emitters for radiative energy conversion and thermal radiation detection. In visible wavelengths the reflectance increases as the temperature increases, because of decreasing emittance but in infrared wavelengths the reflectance and transmittance decrease as the temperature increases. The layer thicknesses need to be optimized to achieve maximum transmittance for the given materials. Maximum transmittance also depends on the type of materials and its temperature.

This paper defines how a meta heuristic search engine called P.S.O can be used to maximize the objective function of a logistic regression model, describing the relationship between the response variable (product designs' score) and a set of explanatory variables (product design factors). At the first phase the processed data, classified and categorized, by Kansie Engineering is used as input to the logistic regression model. The PSO optimization algorithm, maximizes the likelihood function, thus the parameters of the model, being the coefficients of the independent factors are estimated. After post hoc tests, the validated model, defines the relation between consumer semantic and physical product selection factors and the response variable which is a dichotomous dependent ordered variable representing product design scores.