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Feed provided by ADMT Journal. Click to visit.A New Optimal Method for Calculating the Null Space of a Robot using NOC Algorithm; Application ...
http://admt.iaumajlesi.ac.ir/article_672075_1134007.html
In this paper, a new optimal method for modelling of a 3PRS robot is proposed according to NOC algorithm. An optimal method of selecting the generalized coordinate is presented and a new algorithm of extracting the null space of over and under constrained robots is proposed through which a lower amount of mathematical calculations is required. In this method, using the principal of derivatives of implicit functions, the null space of constraint matrix will be extracted. Afterwards the null space matrix is calculated with orthogonal columns. The proposed method is implemented on a 3PRS robot which is an under constrained robot. This robot is a kind of parallel spatial robot with 6 DOFs which can be controlled using 3 active prismatic joints and 3 passive rotary ones. This robot similar to other parallel robots has heavy, complicated and nonlinear model which needs heavy and time consuming mathematical calculations. The proposed strategy of extracting the null space of the robot, extremely and heavily decreases the volume of required mathematical calculations for modelling the robot and consequently decreases the inevitable consumed time of processing and numerical errors and increases the accuracy of simulations.Sat, 29 Feb 2020 20:30:00 +0100High-Velocity Compaction of Aluminum Powder by Gas Detonation Forming Technique
http://admt.iaumajlesi.ac.ir/article_672098_1134007.html
In this paper, a large-scale experimental study has been conducted in order to evaluate the high-velocity compaction of aluminum powder using Gas Detonation Forming (GDF) processing technique. In this series of experiments, the effect of the distribution of grain particle size, initial powder mass, and loading conditions on green density and strength of compacted products were thoroughly studied. The maximum relative green density and green strength of 97.6% and 17.9% were achieved. Group Method of Data Handling (GMDH)-type neural network in conjunction with Singular Value Decomposition (SVD) method was exerted to model the high-velocity compaction process of aluminum powder. The main objective of this idea is to demonstrate how two characteristics of the high-velocity compaction, namely, the relative green density and strength of products vary with the changing of significant parameters, involved in GDF processing technique.Sat, 29 Feb 2020 20:30:00 +0100