Publications by authors named "Roberto Furfaro"

2 Publications

  • Page 1 of 1

Fuel-Efficient Powered Descent Guidance on Large Planetary Bodies via Theory of Functional Connections.

J Astronaut Sci 2020 25;67(4). Epub 2020 Sep 25.

Aerospace Engineering, Texas A&M University, College Station, TX, 77843, USA.

In this paper we present a new approach to solve the fuel-efficient powered descent guidance problem on large planetary bodies with no atmosphere (e.g., Moon or Mars) using the recently developed Theory of Functional Connections. The problem is formulated using the indirect method which casts the optimal guidance problem as a system of nonlinear two-point boundary value problems. Using the Theory of Functional Connections, the problem's linear constraints are analytically embedded into a functional, which maintains a free-function that is expanded using orthogonal polynomials with unknown coefficients. The constraints are always analytically satisfied regardless of the values of the unknown coefficients (e.g., the coefficients of the free-function) which converts the two-point boundary value problem into an unconstrained optimization problem. This process reduces the whole solution space into the admissible solution subspace satisfying the constraints and, therefore, simpler, more accurate, and faster numerical techniques can be used to solve it. In this paper a nonlinear least-squares method is used. In addition to the derivation of this technique, the method is validated in two scenarios and the results are compared to those obtained by the general purpose optimal control software, GPOPS-II. In general, the proposed technique produces solutions of accuracy. Additionally, for the proposed test cases, it is reported that each individual TFC-based inner-loop iteration converges within 6 iterations, each iteration exhibiting a computational time between 72 and 81 milliseconds, with a total execution time of 2.1 to 2.6 seconds using MATLAB. Consequently, the proposed methodology is potentially suitable for real-time computation of optimal trajectories.
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http://dx.doi.org/10.1007/s40295-020-00228-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7553110PMC
September 2020

Solving radiative transfer problems in highly heterogeneous media via domain decomposition and convergence acceleration techniques.

Appl Radiat Isot 2011 Aug 25;69(8):1146-50. Epub 2010 Nov 25.

Aerospace and Mechanical Engineering Department, The University of Arizona, 1130 N Mountain Ave, Tucson, AZ 85721, USA.

This paper deals with finding accurate solutions for photon transport problems in highly heterogeneous media fastly, efficiently and with modest memory resources. We propose an extended version of the analytical discrete ordinates method, coupled with domain decomposition-derived algorithms and non-linear convergence acceleration techniques. Numerical performances are evaluated using a challenging case study available in the literature. A study of accuracy versus computational time and memory requirements is reported for transport calculations that are relevant for remote sensing applications.
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http://dx.doi.org/10.1016/j.apradiso.2010.11.016DOI Listing
August 2011