Generating dynamically feasible trajectory for fixed-wing Unmanned Aerial Vehicles(UAVs)in dense obstacle environments remains computationally *** paper proposes a Safe Flight Corridor constrained sequentialconvex Pr...
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Generating dynamically feasible trajectory for fixed-wing Unmanned Aerial Vehicles(UAVs)in dense obstacle environments remains computationally *** paper proposes a Safe Flight Corridor constrained sequential convex programming(SFC-SCP)to improve the computation efficiency and reliability of trajectory ***-SCP combines the front-end convex polyhedron SFC construction and back-end SCP-based trajectory optimization.A Sparse A^(*)Search(SAS)driven SFC construction method is designed to efficiently generate polyhedron SFC according to the geometric relation among obstacles and collision-free *** transforming the nonconvex obstacle-avoidance constraints to linear inequality constraints,SFC can mitigate infeasibility of trajectory planning and reduce computation ***,SCP casts the nonlinear trajectory optimization subject to SFC into convexprogramming subproblems to decrease the problem *** addition,a convex optimizer based on interior point method is customized,where the search direction is calculated via successive elimination to further improve *** experiments on dense obstacle scenarios show that SFC-SCP can generate dynamically feasible safe trajectory *** studies with state-of-the-art SCP-based methods demonstrate the efficiency and reliability merits of ***,the customized convex optimizer outperforms off-the-shelf optimizers in terms of computation time.
This paper introduces an integrated approach for time-coordinated motion planning of multiple unmanned vehicles using distributed model predictive control (DMPC) and sequential convex programming (SCP). This approach ...
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This paper introduces an integrated approach for time-coordinated motion planning of multiple unmanned vehicles using distributed model predictive control (DMPC) and sequential convex programming (SCP). This approach employs a unified framework that integrates trajectory planning and tracking into a single optimization problem, effectively expanding the domain of attraction for the MPC controller and addressing the challenge of time-coordination among multiple vehicles. Non-uniform discrete time scales are introduced to mitigate the dimensionality of the optimization problem, thereby enhancing computational efficiency. By combining the ability of DMPC to distribute computational efforts across multiple vehicles with the iterative convexification method of SCP, our approach efficiently handles the complexities of non-linear optimization. Theoretical analysis has confirmed the feasibility and stability of the proposed method. Based on this approach, the time-coordinated sequential convex programming-based distributed model predictive control (TC-SCP-DMPC) algorithm is proposed. Numerical simulations are conducted to validate the effectiveness and efficiency of the proposed algorithm in achieving time-coordinated control of multiple unmanned vehicles.
This article tackles the complex challenge of multi-vehicle motion planning by presenting the novel sequential convex programming-based Distributed Model Predictive Control (SCP-DMPC) algorithm. Existing methods often...
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This article tackles the complex challenge of multi-vehicle motion planning by presenting the novel sequential convex programming-based Distributed Model Predictive Control (SCP-DMPC) algorithm. Existing methods often struggle with the nonconvex nature of optimization in multi-vehicle motion planning, frequently compromising on computational efficiency. SCP-DMPC innovatively combines the predictive control of DMPC with the optimization prowess of SCP to address these issues efficiently, while adhering to both physical and operational constraints. To ensure precise attainment of target poses, a three-stage control strategy is introduced, with theoretical analysis on its recursive feasibility and asymptotic stability, enhancing the reliability of the algorithm. Moreover, a heuristic-based deadlock resolution scheme is devised to prevent vehicle stalling, a common issue in cooperative motion. Validated through simulations in challenging scenarios, including symmetric position swapping and obstacle-laden formation transition, SCP-DMPC demonstrates superior adaptability, precision, and efficiency. These results underscore its potential for robust, real-time unmanned vehicle applications, suggesting new directions for future research and development in the field.
sequential convex programming (SCP) has been gaining popularity for space trajectory optimization. However, application of SCP for solar-sail trajectory optimization has suffered from the nonlinear coupling between th...
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sequential convex programming (SCP) has been gaining popularity for space trajectory optimization. However, application of SCP for solar-sail trajectory optimization has suffered from the nonlinear coupling between the magnitude and direction of solar radiation pressure acceleration, which renders the optimal control problem highly nonconvex in the control variables. To address this issue, this paper proposes a formulation that transforms the solar-sail optimal control problem into a problem that is convex with respect to control (called control-convex). This convexification is achieved by introducing a slack variable and applying a change of variable. This paper mathematically shows the lossless property of the proposed control-convex formulation by using Pontryagin's minimum principle, and develops an SCP-based trajectory optimization algorithm for solar sails. We then apply the developed trajectory optimization algorithm to two interplanetary-transfer scenarios, demonstrating its effectiveness in solving complex sail optimal control problems efficiently and robustly, with better optimality compared to a conventional formulation.
This paper proposes an enhanced sequential convex programming-based model predictive control (ESCPMPC) scheme for formation tracking control problems. Considering coupled input constraints, a tracking error dynamic eq...
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This paper proposes an enhanced sequential convex programming-based model predictive control (ESCPMPC) scheme for formation tracking control problems. Considering coupled input constraints, a tracking error dynamic equation is established based on the position error between the leader and the follower, and a model predictive controller (MPC) is formulated for formation tracking. To improve the real-time control capability, we integrate MPC with sequential convex programming (SCP) by linearizing kinematics and convexifying obstacle avoidance constraints, thereby transforming the nonconvex optimization into a series of convex subproblems. While this approach efficiently approximates the solution to the original nonconvex problem, the linearization errors introduced during each SCP iteration can accumulate and potentially make the optimization problem infeasible. To address this issue, we propose an enhanced SCP (ESCP) method, which corrects these linearization errors. To ensure system stability, a terminal controller and a corresponding terminal set are computed. The recursive feasibility and stability of the proposed method are theoretically demonstrated. Finally, numerical simulations validate the effectiveness and computational efficiency of the proposed method in achieving formation tracking control for unmanned vehicles.
This paper proposes a new smoothing-homotopy-based sequential convex programming (SCP) method for general trajectory optimization problems. The surrogates, derived from convolving the smoothing kernel with the termina...
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This paper proposes a new smoothing-homotopy-based sequential convex programming (SCP) method for general trajectory optimization problems. The surrogates, derived from convolving the smoothing kernel with the terminal states, are firstly incorporated into the terminal constraints as replacements of the original ones. The smoothing parameter, taken as the homotopic parameter, decreases from a larger value to zero, with which the corresponding optimization problem gradually transitions from an easier and smoothed counterpart to the original one. Both the modified Chebyshev-Picard iteration (MCPI) approach and the trapezoidal rule are employed to transcribe the continuous-time optimization problem into a series of finite-dimensional subproblems, respectively, which are then solved by the primal-dual interior-point solver with the aid of convexity techniques. Numerical simulations for an ascent trajectory optimization problem are provided to demonstrate the performance of the proposed method, showcasing its superior convergence compared to the standard SCP methods.
This paper introduces an improved method for imposing trust-region constraints within the sequential convex programming framework, particularly aiming to reduce unnecessary iterations in applications for the entry gui...
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This paper introduces an improved method for imposing trust-region constraints within the sequential convex programming framework, particularly aiming to reduce unnecessary iterations in applications for the entry guidance problem. The proposed method leverages the dual solution to detect oscillations in the solution across iterations and to determine whether the solution is near optimal. Subsequently, a penalized form of the trust-region constraint is applied to enhance convergence and accurately satisfy the nonlinear constraints. Numerical simulations on the entry guidance problem are presented to validate the performance of the proposed method. The results demonstrate a significant reduction in the number of iterations, with only a minimal trade-off in cost functional value and convergence success rate.
Usually, an UAV (Unmanned Aerial Vehicle) path planning problem can be modeled as a nonlinear optimal control problem with non-convex constraints in practical applications. However, it is quite difficult to obtain sta...
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Usually, an UAV (Unmanned Aerial Vehicle) path planning problem can be modeled as a nonlinear optimal control problem with non-convex constraints in practical applications. However, it is quite difficult to obtain stable solutions quickly for this kind of non-convex optimization with certain convergence and optimality. In this paper, an algorithm is proposed to solve the problem through approximating the non-convex parts by a series of sequential convex programming problems. Under mild conditions, the sequence generated by the proposed algorithm is globally convergent to a KKT (Karush-Kuhn-Tucker) point of the original nonlinear problem, which is verified by a rigorous theoretical proof. Compared with other methods, the convergence and effectiveness of the proposed algorithm is demonstrated by trajectory planning applications. (C) 2018 Elsevier Masson SAS. All rights reserved.
An on-board guidance generation approach for Mars pinpoint landing has been developed based on sequential convex programming. To optimize the flight time in the formulation, a discretized form of the landing problem w...
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An on-board guidance generation approach for Mars pinpoint landing has been developed based on sequential convex programming. To optimize the flight time in the formulation, a discretized form of the landing problem was constructed under the conditions of linearized states, controls, and time increment between consecutive time steps. To implement this strategy in real time, on-board demonstrations were conducted with the GR740, which is the next-generation on-board processor of choice for the European Space Agency. The total number of time steps was determined based on the results of these demonstrations. The numerically simulated results also indicate that the solution obtained via the proposed strategy is close to the optimized GPOPS-II solution under the condition of no disturbance. Even under disturbances such as navigation errors, initial prediction errors, and perturbation forces, the proposed strategy ensures that the spacecraft reaches its target position with near-optimal fuel consumption. (C) 2021 COSPAR. Published by Elsevier B.V. All rights reserved.
sequential convex programming (SCP) has been extensively utilized in reentry trajectory optimization due to its high computational efficiency. However, the current SCP approaches primarily rely on penalty function, wh...
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sequential convex programming (SCP) has been extensively utilized in reentry trajectory optimization due to its high computational efficiency. However, the current SCP approaches primarily rely on penalty function, where the selection of the penalty function weight presents a significant challenge. In this paper, an improved trust region shrinking SCP algorithm is proposed that separates the treatment of the objective function and constraint violation without the need for selecting penalty function weight and introduction of slack variables. Firstly, from the perspective of multi-objective optimization, the filter and acceptance condition are introduced to ensure that the proposed algorithm converges to feasible solutions and then to the optimal solution based on switching condition and sufficient condition. Then an effective feasibility restoration phase is proposed to address infeasibility of subproblems without introducing slack variables, while ensuring the robustness of the proposed algorithm. Additionally, a theoretical analysis is provided to guarantee the convergence of the algorithm. Finally, simulations are conducted to verify that the proposed algorithm demonstrates a 69.54% improvement in average solution time and stronger robustness compared to basic trust region shrinking SCP algorithm. Simultaneously, the proposed algorithm also demonstrates an advantage in solving speed compared to a particular advanced penalty function-based SCP algorithm.
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