Preface of the “Symposium on numerical optimization and applications”

[Excerpt] Numerical Optimization and Applications Symposium emphasizes modeling, theory and study of numerical algorithms for optimization. Optimization is an important tool in decision science and in the analysis of physical systems. Furthermore the Optimization plays central role in a tremendous variety of application in the natural sciences, in the sectors of economy, finance, and industry operational research and in the engineering. Because of the wide and growing use of optimization, it is important to develop an understanding of optimization algorithms. Knowledge of the capabilities and limitations of these algorithms leads to a better understanding of their impact on various applications, and points the way to future research on improving and extending optimization algorithms and software. [...](undefined

Global vs. local nonlinear optimization techniques for human-like movement of an anthropomorphic robot

In this paper a comparison between using global and local optimization techniques for solving the problem of generating human-like arm and hand movements for an anthropomorphic dual arm robot is made. Although the objective function involved in each optimization problem is convex, there is no evidence that the admissible regions of these problems are convex sets. For the sequence of movements for which the numerical tests were done there were no significant differences between the optimal solutions obtained using the global and the local techniques. This suggests that the optimal solution obtained using the local solver is indeed a global solution

Parameter estimation of viscoelastic materials : a test case with different optimization strategies

In this work, and based on numerical optimization techniques, constitutive parameters for viscoelastic materials are determined using a inverse problem formulation. The optimization methodology is based on experimental results obtained in the frequency domain, for a CFRP-Carbon Fibre Reinforced Polymer, through DMA-Dynamic Mechanical Analysis. The relaxation modulus of viscoelastic materials is given by a summation of decaying exponentiating functions, known as Prony series. Prony series, in time domain, are normally used to determine constitutive parameters for viscoelastic materials. In this paper, using the Fourier transform of the time domain Prony series, a nonlinear constrained least square problem based on Prony series representations of storage and loss modulus, for the considered material, is analyzed. A case study considering the estimation of 2N viscoelastic parameters, N = 1,2, ···11, is taken as a benchmark. The nonlinear constrained least square problems are solved using global and local optimization solvers. The computational results as well as the main conclusion are shown

A modified fractional zener model to describe the behaviour of a carbon fibre reinforced polymer

In this work a modified conventional Fractional Zener Model is deduced and applied to estimate the viscoelastic constitutive parameters of a Carbon Fibre Reinforced Polymer. The accuracy of this modified model was studied against conventional Fractional Zener model and Fractional Maxwell model, considering experimental data in the frequency domain. The set of parameters was found by solving a nonlinear constrained least square problem based on the variation of the storage and loss moduli with frequency.This work was financed by FEDER funds through COMPETE (Operational Programme Thematic Factors of Competitiveness) and by portuguese funds through FCT (Foundation for Science and Technology) within the project PEst-C/MAT/UI0013/ 2011

Practical implementation of an interior point nonmonotone line search filter method

Versão não definitiva do artigoHere we present a primal-dual interior point nonmonotone line search filter method for nonlinear programming. The filter relies on three measures, the feasibility, the centrality and the optimality presented in the optimality conditions, considers relaxed acceptability criteria for the step size and includes a feasibility restoration phase. The evaluation of the method is until now made on small problems and a comparison is provided with a merit function approach

Comparison of filter line search algorithms in the primal-dual barrier approach for nonlinear programming

In this paper, we present a new filter line search method based on two measures that is integrated into the primal-dual barrier method developed by Wachter and Biegler [Mathematical Programming 106 (2006), pp. 25--57] for nonlinear programming. One measure arises directly from the first order optimality conditions of the problem and the other is the barrier function. Primary assessment of the method has been done with a well-known collection of problems and compared with the solver IPOPT.Fundação para a Ciência e a Tecnologia (FCT

Nonlinear optimization for human-like movements of a high degree of freedom robotics arm-hand system

The design of autonomous robots, able to closely cooperate with human users in shared tasks, provides many new challenges for robotics research. Compared to industrial applications, robots working in human environments will need to have human-like abilities in their cognitive and motor behaviors. Here we present a model for generating trajectories of a high degree of freedom robotics arm-hand system that reflects optimality principles of human motor control. The process of finding a human-like trajectory among all possible solutions is formalized as a large-scale nonlinear optimization problem. We compare numerically three existing solvers, IPOPT, KNITRO and SNOPT, in terms of their real-time performance in different reach-to-grasp problems that are part of a human-robot interaction task. The results show that the SQP methods obtain better results than the IP methods. SNOPT finds optimal solutions for all tested problems in competitive computational times, thus being the one that best serves our purpose.Eliana Costa e Silva was supported by FCT (grant: SFRH/BD/23821/2005). The resources and equipment were financed by FCT and UM through project "Anthropomorphic robotic systems: control based on the processing principles of the human and other primates motor system and potential applications in service robotics and biomedical engineering" (Ref. CONC-REEQ/17/2001) and by EC through project "JAST: Joint-Action Science and Technology" (Ref. IST- 2-003747-IP).We thank the Mobile and Anthropomorphic Robotics Laboratory at University of Minho for constant good work environment. Finally, we would like to thank Carl Laird and Andreas Wachter for making available IPOPT, and AMPL for making available an unrestricted 30 days trial version of AMPL, KNITRO and SNOPT executables

A three-D filter line search method within an interior point framework

Here we present a primal-dual interior point three-dimensional filter line search method for nonlinear programming. The three components of the filter aim to measure adequacy of feasibility, centrality and optimality of trial iterates. The algorithm also relies on a monotonic barrier parameter reduction and it includes a feasibility/centrality restoration phase. Numerical experiments with a set of well-known problems are carried out and a comparison with a previous implementation that differs on the optimality measure is presented

Human-like movement of an anthropomorphic robot: problem revisited

Human-like movement is fundamental for natural human-robot interaction and collaboration. We have developed in a model for generating arm and hand movements an anthropomorphic robot. This model was inspired by the Posture-Based Motion-Planning Model of human reaching and grasping movements. In this paper we present some changes to the model we have proposed in [4] and test and compare different nonlinear constrained optimization techniques for solving the large-scale nonlinear constrained optimization problem that rises from the discretization of our time-continuous model. Furthermore, we test different time discretization steps.Eliana Costa e Silva was supported by FCT (grant: SFRH/BD/23821/2005)