A branch and bound approach for minimizing the energy consumption of an electrical vehicle

National audienceIn this paper we discuss about the way to approximate the solution of an optimal control problem with a switched command. Our Method is based on a discretization technique associated with a Branch and Bound algorithm. The problem that we focus on is the minimization of the consumption of the energy of an electrical vehicle during some imposed displacements

Hybridizing direct and indirect optimal control approaches for aircraft conflict avoidance

Aircraft conflict avoidance is a crucial issue arising in air traffic management. The problem is to keep a given separation distance for aircraft along their trajectories. We focus on an optimal control model based on speed regulation to achieve aircraft separation. We propose a solution strategy based on the decomposition of the problem and on the hybridization of a direct and an indirect method applied on the obtained subproblems. Numerical results show that the proposed approach is promising in terms of reduction of computing time for conflict avoidance

A decomposition-based optimal control approach for aircraft conflict avoidance performed by velocity regulation

International audienceOne of the decisive tasks within the air traffic management is the resolution of aircraft conflict avoidance problems. To avoid conflict, aircraft have to preserve a minimal safety distance between them. In this paper, we present optimal control models and approaches based on speed regulation to perform aircraft conflict avoidance. We consider some aircraft configurations with separable trajectories, i.e., such that trajectories of aircraft pairs exhibit conflict zones which are each other separated in terms of time and/or space. We propose a decomposition of the problem in such a way to solve independently subproblems of the original one

Frequency assignment in a SDMA satellite communication system with beam decentring feature

International audienceIn satellite communication, Spatial Division Multiple Access (SDMA) has become one of the most promising techniques that can accommodate continuing increase in the number of users and traffic demands. The technology is based on radio resource sharing that separates communication channels in space. It relies on adaptive and dynamic beam-forming technology and well-designed algorithms for resource allocation among which frequency assignment is considered. This paper studies static Frequency Assignment Problem (FAP) in a satellite communication system involving a satellite and a number of users located in a service area. The objective is to maximize the number of users that the system can serve while maintaining the signal to interference plus noise ratio of each user under a predefined threshold. Traditionally, interference is treated as fixed (binary interferences or fixed minimal required separation between frequencies) . In this paper, the interference is cumulative and variable. To solve the problem, we work on both discrete and continuous optimizations. Integer linear programming formulations and greedy algorithms are proposed for solving the discrete frequency assignment problem. The solution is further improved by beam decentring algorithm which involves continuous adjustment of satellite beams and deals with non-linear change of interference

Optimal time control to swing-up the inverted pendulum-cart in open-loop form

National audienceThis work deals with simulation on an Inverted Pendulum (IP). The control strategy of an IP is split into two main control phases: (i) swing-up control to bring back the pendulum from the downward position to the upward one, and (ii) upright stabilization control to maintain the pendulum to the upright vertical position. In the case (ii), a feedback or a neuro-fuzzy controller is used to stabilize the pendulum cart, while in the first case (i), a non-linear controller based on the energy of the pendulum is used in order to reach the desired performance with a minimum number of swings. Our contribution is to present a simulation using MatLab of time-optimal control system for swinging-up the pendulum, with a single control law in an open-loop form. From the bang-bang structure of the time-optimal control resulting from the necessary condition of the Pontryagin Maximum Principle, the solution obtained from direct discretization method is adjusted by using Newton based method

Optimization of the control of a doubly fed induction machine

National audienceThis paper focuses on finding an optimal control for a doubly fed induction machine (DFIM) in motor mode. Our purpose is not to improve the quality of the DFIM functioning but to find a method to improve it. Thus we will start with a fixed system made by a DFIM and two ideal 3 phases voltage inverter with an open loop static V/f control. A method will demonstrate its efficiency to improve that control for the copper loss. This method is based on direct shooting techniques associated with a MATLAB optimization solver:fmincon

HEURISTICS AND LOWER BOUND FOR ENERGY MANAGEMENT IN HYBRID-ELECTRIC VEHICLES

International audienc

A better alternative to dynamic programming for offline energy optimization in hybrid-electric vehicles

International audienceThis article focusses on the well-known problem of energy management for hybrid-electric vehicles. Although researches on this problem have recently intensified. Dynamic programming (DP) is still considered as the reference method because it obtains the best solutions of the literature so far, even though it requires a significant computational time. This article however, describes two heuristic-global-optimization-based algorithms that not only require less computational time than DP, but also produce better solutions, with significantly lower fuel consumption cost

Reduced RLT constraints for polynomial programming

International audienceAn extension of the reduced Reformulation-Linearization Technique constraints from quadratic to general polynomial programming problems with linear equality constraints is presented and a strategy to improve the associated convex relaxation is proposed

Design of slotless permanent magnet machines by a semi-infinite global optimization method

An efficient way to design slotless permanent magnet machines is to associate analytical models with deterministic global optimization algorithms. In this paper, we propose to extend these design approaches in order to take into account the torque ripples. This involves the study of a semi-infinite optimization problem. To solve it, a discretization method associated with an exact Branch and Bound global optimization solver is developed. This new approach is validated on some numerical tests showing that efficient global optimal solutions with torque ripples about 5 % (instead of 30 %) can be so-obtained