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Traffic issue is an international challenge in the sophisticated countries in which over population is considered as an important factor in creating this problem. Studies show that the accidents’ report during the minimum time is the best way to control the traffics. For this purpose, this paper has been done in such a way that after modeling the flying robot using Newton-Euler equations, a three-dimensional constrained optimal trajectory has been generated through Direct Collocation Approach. In other words, the proposed problem in this paper is first formulated as an optimal control problem. Afterwards, the optimal control problem is discretized through Direct Collocation Technique, which is one of the numerical solving methods of the optimal control problems, and it is transformed into a Nonlinear Programing Problem (NLP). Eventually, the aforementioned nonlinear programming problem is solved via SNOPT which works based on the gradient algorithm like SQP. It should be noted that since the main objective of motion planning in this paper is controlling the urban traffic, the urban constrains are utilized during the trajectory optimization. In other words, all of the high-rise buildings located during the course are modeled by the various cylinders. The efficacy of the aforementioned method is demonstrated by extensive simulations, and in particular it is verified that this method is capable of producing a suitable solution for three-dimensional constrained optimal motion planning for a six-degree-of-freedom quadrotor helicopter for urban traffic purposes.

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In this paper, simulation and time-optimal control of an electro-dynamic tether system as a new and inexpensive form of space propulsion system are investigated. The EDT, can provide desired acceleration by interaction between a current in the tether wire and earth’s magnetic field, without any fuel consumption, for any orbital maneuvering. For this reason, it is an appropriate choice for space debris mitigation missions. In this work, firstly, dynamics of the EDT, together with the earth’s magnetic field are simulated. Secondly, exploiting the developed simulation tool-set, variations of classical orbital elements are observed and then feasibility studies of non-impulsive orbital maneuvers are conducted. In this manuscript, distinctly, relative motion and rendezvous by means of the EDT, adoption of appropriate coordinate system, problem conditions and also the method of solution are discussed. Simulation results demonstrate that the EDT can perform a wide range of in-plane and out-of-plane orbital maneuvers in low-earth-orbits (LEO). Eventually, an in-plane rendezvous problem with space debris, is solved by implementation of Direct Collocation method in Matlab by developing a solver program and resolving its limitations with respect to optimal rendezvous problem using electrodynamic tether, and then optimal control in a minimum-time condition, and also optimal trajectory are obtained.

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In this paper, using both linear and nonlinear identification methods based on iterative and recursive least-square, the performance of a backstepping control system of a quadrotor in the presence of uncertainties is improved. At first, the dynamic model of a quadrotor is introduced and descriptive equations are presented in an appropriate state-space in order to design a controller based on backstepping method. Then the backstepping controller is designed using virtual controller for trajectory tracking. In this control system, the control performance is not satisfying because of the physical uncertainties existed in quadrotor. Consequently, an online identification method is introduced and used to improve the performance of the controller. In this regard, some parameters, which are linear in the model structure, are identified by least square error technique and iterative least square method is used for identifying other parameters.The results indicate that the steady-state error is decreased and the ability of tracking of a desired trajectory in the presence of uncertainties is increased. Furthermore, the result demonstrate the stabilization of roll and pitch angles, while, the method prevents the vibration of control forces.