A Technique Based on Adaptive Extended Jacobians for Improving the Robustness of the Inverse Numerical Kinematics of Redundant Robots

The extended Jacobian is a technique for solving the redundancy of redundant robots. It is based on the definition of secondary tasks, through constraint functions that are added to the mapping between joint rates and end-effector's twist. Several approaches showed its potential, applications, and limitations. In general, the constraint functions are a linear combination of basic functions with constant coefficients. This paper proposes the use of adaptive coefficients in such functions by using the conditioning index of the extended Jacobian as a quality measure. A good conditioning index of the extended Jacobian keeps the robot far from singularities and contributes to the solution of the inverse kinematics. In this paper, initially, the extended Jacobian and the proposed algorithm are discussed, and then, two tests in different circumstances are presented in order to validate the proposal.

Adaptive Extended Jacobian Can Improve the Global Conditioning Index of Redundant Robots

The extended Jacobian is a solution technique of redundant robot’s instantaneous kinematics. It is based on the definition of secondary tasks through constraint functions that are added to the mapping between joint rates and end-effector’s twist. Several approaches showed its potential, its applications and limitations. In general, the constraint functions are a linear combination of basic functions with constant coefficients. This paper proposes the use of adaptive coefficients in such equations by using the conditioning index of the extended Jacobian as a quality measure. A good conditioning of the extended Jacobian keeps the robot far from singularities and contributes to the solution of the inverse kinematics. In this paper, initially the extended Jacobian and the proposed algorithm are discussed, then two tests in different circumstances are presented to validate the proposal.

Subspace Identification of Hammerstein Model with Unified Discontinuous Nonlinearity

The main aim of this study is to handle the case where the structures of nonlinear systems are unknown. In the many works, the parametric identification of nonlinear systems represented by Hammerstein model, with discontinuous and asymmetric nonlinearity, considers the structures of the nonlinear and linear blocks are known, especially the nonlinear bloc. To solve this problem, a unified form of nonlinearity representing eight cases of nonlinearities can be used. The parameters of both blocks, linear and nonlinear, are estimated using an iterative subspace approach. More importantly, in an attempt to show the extent to which this method is efficient, we apply it to experimental data obtained from the electropneumatic system. As a result, the numerical and experimental examples confirm a good conditioning and computational efficiency.

Morphological Analysis of Dentin Surface after Conditioning with Two Different methods: Chemical and Mechanical

ABSTRACT Background Alternative pretreatment strategies of dentin and adhesionare constantly being developed and studied with the goal of improving the adhesion of resin restorative materials with this tissue. The objectives of the present study were to evaluate the ability of airborne-particle abrasion (APA) with aluminum oxide on dentin to remove the smear layer and the effects produced on the dentin microstructure. Materials and methods The phosphoric acid (PA) was used for a comparison. For that, 20 human third molars were randomly allocated into two experimental groups, according to the dentin pretreatment method used: G1 (N = 10) – PA, G2 (N = 10) – APA. For dentin surface analyses, an environmental scanning electron microscope (ESEM) was employed to observe dentin surfaces before and after the procedures. Before pretreatment, the specimens of both groups were smear covered. Results After pretreatment, the G1 images revealed dentin tubule orifices opened, enlarged and some erosive effects. (G2) exposed tubule orifices without enlargement, but crack-like alterations were observed on the surfaces. In this way, APA with aluminum oxide was able to remove the smear layer. Conclusion The influences of the dentin roughness on adhesion and the consequences on dentin integrity and hardness need further investigations. Clinical significance A good conditioning of the dentin before cementation is necessary in order to obtain a satisfactory rehabilitation in adhesive dentistry. So, it is necessary to know all methods to do it. How to cite this article Rafael CF, Quinelato V, Morsch CS, DeDeus G, Reis CM. Morphological Analysis of Dentin Surface after Conditioning with Two Different methods: Chemical and Mechanical. J Contemp Dent Pract 2016;17(1):58-62.

Investigation of the impact using neuroanatomy specimens prepared using new anatomical techniques on students' learning

Introduction: Neuroanatomy specimens have greater fragility than other anatomy specimens and their useful life depends on good conditioning and protection. The difficulty in obtaining human specimens has increased the demand for preparations that might make such specimens more durable. Objective: transform the collection of neuroanatomy specimens in the anatomy laboratory into specimens that were more instructive for students, through more refined anatomical techniques, thereby improving the appearance and preservation of these specimens, and also to develop a scientific study on the importance of this type of didactic-pedagogical tool. Material and Methods: After preparing the specimens and using them in the classroom, we applied a questionnaire to evaluate the learning process, with regard to ease of handling the specimens, improvement of instruction and construction of knowledge. We gathered responses from 53 students in their fourth teaching semester of the biomedicine course at the Methodist University of São Paulo. Results: after the treatment to clarify and demarcate anatomical structures in the neuroanatomical specimens that was put forward in this study, an effective improvement in the students' study method was demonstrated (100%). Conclusions: The objectives proposed by the discipline were achieved in terms of yield (92.5%) and understanding of theory during practical classes (98%), thus generating student behavior that was more positive. In relation to handling and discomfort relating to the smell of the old specimens, there was an improvement of 88.7% through using the current specimens. There was also an improvement in learning outside of the classroom hours (86.4%).

A Closed-Form Optimal Kinematic Design of the PRRRP Parallel Manipulator

This paper addresses the optimal kinematic design of the PRRRP parallel manipulator that is actuated horizontally by linear actuators. Kinematically, the symmetrical PRRRP parallel manipulator has only one geometric parameter, i.e., the link length of each of the two legs. Here, we propose a design approach utilizing the performance chart and local performance specification. The key problem in the design of the manipulator is the determination of not the link length but the workspace that the manipulator can reach satisfying the design specification. Such a kind of workspace when the link length is unit is defined as the basic good-conditioning workspace (GCW). For the manipulator studied here, the link length is actually the ratio of the desired task workspace to the basic GCW. This paper gives an effective method to obtain the basic GCW with respect to indices in closed form. One of the advantages of the method is that the basic GCW is achieved by taking into account both the global and local indices.

E-Expectancy and the Role of Awareness in Verbal Conditioning

Different groups of Es were led to expect that verbal conditioning either could or could not occur without awareness. Both groups tested independent sets of 19 Ss who constructed 100 sentences beginning with one of six pronouns and containing a past tense verb. For experimental Ss sentences beginning with I or We were reinforced by the word “good.” Conditioning effects were as predicted by the expectancies of Es. Ss who were unaware of the correct contingency conditioned only in the group tested by Es who were led to expect that result.