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Direct-adaptive fuzzy path following control for an autonomous airship

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Abstract

A direct-adaptive fuzzy path following control method for an autonomous airship is presented, which comprises path following control and adaptive fuzzy control. Firstly, based on the planar dynamic model of the airship, the path following control is designed consisting of guidance law, yaw tracking and velocity control. Then, a direct-adaptive fuzzy controller is constructed to approximate the unknown terms caused by system model uncertainties and external disturbances. It is proved that the proposed controller can make the airship track the desired path and force the tracking error to converge to a small neighborhood of the origin. Simulation results show the effectiveness of the proposed method.

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... Path following is one of the typical control scenarios for marine surface vehicles (MSVs) and it pertains to follow a geometrical path, which only involves a spatial constraint. There have been a number of results focused on the subject of designing path following strategies [1][2][3][4][5][6][7][8][9][10][11][12]. A complete path following strategy consists of three parts: the path planing, the guidance, and the velocity controller. ...
... In addition to the path-planning problem, it is of great importance to design a guidance system that steer the vehicle toward or stay on a path. A popular and effective guidance algorithm adopted in path following is the LOS guidance [4][5][6][7][8][9]. In [5], an LOS based path following design is presented for pipe surveying using a low cost autonomous vehicle. ...
... In fact, although the sideslip is relatively small, it largely affects the performance of the path following. In [7,8], this problem is solved by calculating the sideslip angle using the measurements of velocities in surge and sway. The main drawback of this approach is the fact that the measurements from sensors are noisy and include errors, resulting in significant error during along-term path following. ...
Article
This paper addresses three interrelated problems concerning the path following of marine surface vehicles, namely, the path planning, the guidance, and the velocity controller design. A modified cubic spline interpolation technique is employed to design a path that is connected by a series of way-points. The line-of-sight (LOS) algorithm is applied in guidance system design, where the drift force due to the vehicle sideslip is compensated by an integral term. The velocity controller is designed by combining the dynamic surface control (DSC) design and a novel predictor based iterative neural network (PINN) control method. Specifically, neural network (NN) with iterative updating laws based on prediction errors are proposed to identify the dynamical uncertainty and time-varying ocean disturbances. Using a Lyapunov-Krasovskii functional, it is proven that all error signals in the system are uniformly ultimately bounded. Comparison studies are given to show the effectiveness of the proposed method.
... Airship autonomous control mainly includes the fixed point hovering [3]- [5], the trajectory tracking [6]- [9] and the path following [10]- [12]. Compared with the trajectory tracking, the path following is carried out without the requirement of the tracking time, and tracking the desired path under the designed velocity. ...
... Based on the results in [10] and [11], the adaptive fuzzy path following controllers ere redesigned to ensure the global bounded stability of the closed-loop systems. Since the flight velocity of the airship and the wind velocity are similar, then the unknown wind were considered as the unknown disturbances in [12]. Thus the stability of the closedloop systems is guaranteed based on the robustness of the controllers, so that the results are very conservative. ...
... The O g x g axis points to the north, the O g z g axis points to the earth core and the O g y g axis points to east. From [4][7][8] [12], the planar model of the airship in the wind can be derived as follows. ...
... Zheng utilizes sensors of velocities to measure the sideslip angle, and the effect of sideslip is compensated simultaneously. 11 In fact, the sensors are expensive and they are easily polluted by noise, which may generate large tracking error and oscillations during path following. Aiming at eliminating the effect of sideslip, an integral LOS guidance is proposed originally, 12 and the system dynamics are presented with absolute velocities, which requires an additional adaptive scheme to compensate unknown disturbances. ...
... However, only straight line is considered as the desired path of those studies. [10][11][12][13][14] An integral LOS path following approach is developed 15 for continuous curved path, which is locally interpolated by cubic hermite spline method through all predefined waypoints (WPs) and it is able to expand with new added WPs. The issue of compensating for sideslip angle is emphasised and the stability of the integral LOS method is illustrated explicitly. ...
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