scholarly journals The application of the finite rotation and displacement method for a manipulator of a sequential structure with kinematic pairs of the fifth class

2018 ◽  
pp. 1-16
Author(s):  
Alexander Vladimirovich Danilov ◽  
Alexander Nicolayevich Kropotov ◽  
Oleg Vsevolodovich Trifonov
Author(s):  
А. Данилов ◽  
A. Danilov

The article consider the test simulation of the «finite rotation and displacement» method (FRDM) when the European Robotic Arm (ERA) manipulator is passing through the singular points. The test simulation confirms the method’s efficiency when passing through singular points and shows how to control the manipulator with various manifestations of the singularity. Depending on the type of singularities manifestation the manipulator is controlled in the vicinity of the singular point by means of small changes in its configuration or by limiting and setting specific values to generalized coordinates at the software and hardware level. The FRDM method is designed to solve the inverse kinematics (IK) for sequential-structure manipulators with an arbitrary number of links connected by fifth-class kinematic pairs. The method is based on determining the exact and optimal iterative steps that provide the maximum approximation to the given parameters of the final link for each degree of mobility. The software has been developed that consists of subprograms for organizing a general solution of the IK and a particular one for a particular manipulator in the form of source data according to the algorithm of the method. The initial data are the vector model of the manipulator, the values of the structural constraints of the generalized coordinates and signs of kinematic pairs by type and class.


Author(s):  
A. Danilov

The article deals with the application of the "finite rotation and displacement" method (FRDM) which can find the desired values of the generalized coordinates for the control system of a parabolic antenna. The special manipulator of a sequential structure with sufficient rigidity is used to control the parabolic antenna. The rigidity of this manipulator is ensured by use of links in the form of spherical shells and bearings located along the perimeter of each shell in the rotation plane of each link. It allows to optimally place the material of the manipulator's design and to obtain sufficient rigidity with minimal weight. The manipulator consists of four links connected by fifth class kinematic pairs with an arbitrary inclination of the axes. For this task the antenna's orientation is important without taking into account the small displacement of its position during the process of its orientation. The FRDM method provides both orientation and position. It is based on determining the precise and optimal iterative steps for each degree of mobility, providing maximum approximation to the specified orientation parameters of the parabolic antenna. According to the method's algorithm, the software is developed consisting of subprograms for organizing a general solution of the inverse kinematics for an arbitrary number of links and a particular one for a manipulator in the form of source data. The initial data are the vector model of the manipulator, the values of the structural constraints of the generalized coordinates, and the characteristics of kinematic pairs by type and class


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abdulkadir Tasdelen ◽  
Baha Sen

AbstractmiRNAs (or microRNAs) are small, endogenous, and noncoding RNAs construct of about 22 nucleotides. Cumulative evidence from biological experiments shows that miRNAs play a fundamental and important role in various biological processes. Therefore, the classification of miRNA is a critical problem in computational biology. Due to the short length of mature miRNAs, many researchers are working on precursor miRNAs (pre-miRNAs) with longer sequences and more structural features. Pre-miRNAs can be divided into two groups as mirtrons and canonical miRNAs in terms of biogenesis differences. Compared to mirtrons, canonical miRNAs are more conserved and easier to be identified. Many existing pre-miRNA classification methods rely on manual feature extraction. Moreover, these methods focus on either sequential structure or spatial structure of pre-miRNAs. To overcome the limitations of previous models, we propose a nucleotide-level hybrid deep learning method based on a CNN and LSTM network together. The prediction resulted in 0.943 (%95 CI ± 0.014) accuracy, 0.935 (%95 CI ± 0.016) sensitivity, 0.948 (%95 CI ± 0.029) specificity, 0.925 (%95 CI ± 0.016) F1 Score and 0.880 (%95 CI ± 0.028) Matthews Correlation Coefficient. When compared to the closest results, our proposed method revealed the best results for Acc., F1 Score, MCC. These were 2.51%, 1.00%, and 2.43% higher than the closest ones, respectively. The mean of sensitivity ranked first like Linear Discriminant Analysis. The results indicate that the hybrid CNN and LSTM networks can be employed to achieve better performance for pre-miRNA classification. In future work, we study on investigation of new classification models that deliver better performance in terms of all the evaluation criteria.


RSC Advances ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 2226-2234
Author(s):  
Ana María Pineda-Reyes ◽  
Mauricio Hernández Delgado ◽  
María de la Luz Zambrano-Zaragoza ◽  
Gerardo Leyva-Gómez ◽  
Nestor Mendoza-Muñoz ◽  
...  

A novel solvent emulsification-displacement method for obtaining polystyrene nanoparticles is reported. This process has an added value and can be an alternative for the recycling of expanded polystyrene.


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