Unmanned Aerial Vehicles (UAVs) are aircraft that can be autonomously operated and doesn't need a pilot aboard. Consequently, the autopilot is one of the main parts of an UAV, being responsible for stabilising the...
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ISBN:
(纸本)9781728129990
Unmanned Aerial Vehicles (UAVs) are aircraft that can be autonomously operated and doesn't need a pilot aboard. Consequently, the autopilot is one of the main parts of an UAV, being responsible for stabilising the aircraft during the flight, executing navigation tasks and sensing the environment. Several path-following simulations for loiter paths are described in the literature, but most of them only consider the kinematics model of an aircraft. Therefore, this paper compares path-following algorithms for loiter paths in a more realistic scenario, using Software-in-the-Loop simulations and considering the dynamic model of the aircraft in the flight simulator X-Plane. The algorithms compared are: Carrot-Chasing, Pure Pursuit and Line-of-Sight (PLOS) and Non-Linear Guidance Law (NLGL). Lastly, a new algorithm (NLGL+) is proposed with a modification from the original algorithm and its results show smaller errors and less effort than all path-following algorithms.
Unmanned Aerial Vehicle (UAV) is a growing research topic due to its wide range of applications. One of its major challenges is the development of the autopilot, responsible for keeping the aircraft in desired flight ...
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ISBN:
(数字)9783319614038
ISBN:
(纸本)9783319614038;9783319614021
Unmanned Aerial Vehicle (UAV) is a growing research topic due to its wide range of applications. One of its major challenges is the development of the autopilot, responsible for keeping the aircraft in desired flight conditions and for executing navigation tasks. A navigation task that is usually necessary is the path-following, which guarantees that the aircraft follows a predefined trajectory. It is possible to find several approaches for this function, based in geometric and control techniques;however, compared only for the 2D scenario. Therefore, this paper objective is to present new extended path-following algorithms for the 3D scenario, based in the well-known path-following algorithms Lookahead, Non-Linear Guidance Law (NLGL), Pure Pursuit and Line-of-Sight (PLOS) and Vector Field. The algorithms parameters are obtained with Genetic Algorithm optimisation and a comparison between all of them is performed in an environment with and without wind. The results from the simulations show that Vector Field has the best performance and PLOS has the worse one due to a high effort demanded.
We establish an equivalence between the ℓ2-regularized solution path for a convex loss function, and the solution of an ordinary differentiable equation (ODE). Importantly, this equivalence reveals that the solution p...
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We establish an equivalence between the ℓ2-regularized solution path for a convex loss function, and the solution of an ordinary differentiable equation (ODE). Importantly, this equivalence reveals that the solution path can be viewed as the flow of a hybrid of gradient descent and Newton method applying to the empirical loss, which is similar to a widely used optimization technique called trust region method. This provides an interesting algorithmic view of ℓ2 regularization, and is in contrast to the conventional view that the ℓ2 regularization solution path is similar to the gradient flow of the empirical loss. New path-following algorithms based on homotopy methods and numerical ODE solvers are proposed to numerically approximate the solution path. In particular, we consider respectively Newton method and gradient descent method as the basis algorithm for the homotopy method, and establish their approximation error rates over the solution path. Importantly, our theory suggests novel schemes to choose grid points that guarantee an arbitrarily small suboptimality for the solution path. In terms of computational cost, we prove that in order to achieve an ε-suboptimality for the entire solution path, the number of Newton steps required for the Newton method is O(ε-1/2), while the number of gradient steps required for the gradient descent method is O(ε-1 ln(ε-1)). Finally, we use ℓ2-regularized logistic regression as an illustrating example to demonstrate the effectiveness of the proposed path-following algorithms.
In this paper a unified treatment of algorithms is described for linear programming methods based on the central path. This path is a curve along which the cost decreases, and that stays always far from the boundary o...
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In this paper a unified treatment of algorithms is described for linear programming methods based on the central path. This path is a curve along which the cost decreases, and that stays always far from the boundary of the feasible set. Several parameterizations of this curve are described in primal and primal-dual problems, and it is shown how different algorithms are obtained by following the curve using different parameterizations. Polynomial algorithms are obtained by following the curve approximately, and this concept becomes precise by using explicit rules for measuring the proximity of a point in relation to the central path.
Based on the recent theoretical results of Zhao and Li [Math. Oper. Res., 26 (2001), pp. 119-146], we present in this paper a new path-following method for nonlinear P* complementarity problems. Different from most ex...
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Based on the recent theoretical results of Zhao and Li [Math. Oper. Res., 26 (2001), pp. 119-146], we present in this paper a new path-following method for nonlinear P* complementarity problems. Different from most existing interior-point algorithms that are based on the central path, this algorithm tracks the "regularized central path" which exists for any continuous P* problem. It turns out that the algorithm is globally convergent for any P* problem provided that its solution set is nonempty. By different choices of the parameters in the algorithm, the iterative sequence can approach to different types of points of the solution set. Moreover, local superlinear convergence of this algorithm can also be achieved under certain conditions.
We prove the superlinear convergence of the primal-dual infeasible interior-point path-following algorithm proposed recently by Kojima, Shida, and Shindoh and by the present authors, under two conditions: (i) the semi...
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We prove the superlinear convergence of the primal-dual infeasible interior-point path-following algorithm proposed recently by Kojima, Shida, and Shindoh and by the present authors, under two conditions: (i) the semidefinite programming problem has a strictly complementary solution;(ii) the size of the central path neighborhood approaches zero. The nondegeneracy condition suggested by Kojima, Shida, and Shindoh is not used in our analysis. Our result implies that the modified algorithm of Kojima, Shida, and Shindoh, which enforces condition (ii) by using additional corrector steps, has superlinear convergence under the standard assumption of strict complementarity. Finally, we point out that condition (ii) can be made weaker and show the superlinear convergence under the strict complementarity assumption and a weaker condition than (ii).
This paper considers the joint design of user power allocation and relay beamforming in relaying communications, in which multiple pairs of single-antenna users exchange information with each other via multiple-antenn...
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This paper considers the joint design of user power allocation and relay beamforming in relaying communications, in which multiple pairs of single-antenna users exchange information with each other via multiple-antenna relays in two time slots. All users transmit their signals to the relays in the first time slot while the relays broadcast the beamformed signals to all users in the second time slot. The aim is to maximize the system's energy efficiency (EE) subject to quality-of-service (QoS) constraints in terms of exchange throughput requirements. The QoS constraints are nonconvex with many nonlinear cross-terms, so finding a feasible point is already computationally challenging. The sum throughput appears in the numerator while the total consumption power appears in the denominator of the EE objective function. The former is a nonconcave function and the latter is a nonconvex function, making fractional programming useless for EE optimization. Nevertheless, efficient iterations of low complexity to obtain its optimized solutions are developed. The performance of the multiple-user and multiple-relay networks under various scenarios is evaluated to show the merit of the proposed method.
A wireless network of multiple transmitter-user pairs overheard by an eavesdropper, where the transmitters are equippedwith multiple antennas, while the users and eavesdropper are equipped with a single antenna, is co...
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A wireless network of multiple transmitter-user pairs overheard by an eavesdropper, where the transmitters are equippedwith multiple antennas, while the users and eavesdropper are equipped with a single antenna, is considered. At different levels of wireless channel knowledge, the problem of interest is beamforming to optimize the users' quality-of-service (QoS) in terms of their secrecy throughputs or maximize the network's energy efficiency under users' QoS. All these problems are seen as very difficult optimization problems with many nonconvex constraints and nonlinear equality constraints in beamforming vectors. The paper develops path-following computational procedures of low complexity and rapid convergence for the optimal beamforming solution. Their practicability is demonstrated through numerical examples.
This paper provides a theoretical foundation for efficient interior-point algorithms for convex programming problems expressed in conic form, when the cone and its associated barrier are self-scaled. For such problems...
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This paper provides a theoretical foundation for efficient interior-point algorithms for convex programming problems expressed in conic form, when the cone and its associated barrier are self-scaled. For such problems we devise long-step and symmetric primal-dual methods. Because of the special properties of these cones and barriers, our algorithms can take steps that go typically a large fraction of the way to the boundary of the feasible region, rather than being confined to a ball of unit radius in the local norm defined by the Hessian of the barrier.
An infinite-dimensional convex optimization problem with the linear-quadratic cost function and linear-quadratic constraints is considered, We generalize the interior-point techniques of Nesterov-Nemirovsky to this in...
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An infinite-dimensional convex optimization problem with the linear-quadratic cost function and linear-quadratic constraints is considered, We generalize the interior-point techniques of Nesterov-Nemirovsky to this infinite-dimensional situation. The complexity estimates obtained are similar to finite-dimensional ones. We apply our results to the linear-quadratic control problem with quadratic constraints. It is shown that for this problem the Newton step is basically reduced to the standard LQ problem.
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