This article investigates practical tracking joint with obstacle‐avoidance for a class of uncertain robotic systems. The remarkable features are revealed from two aspects. First, more serious system uncertainties are allowed than the related literature due to the presence of unknown system matrices and mismatched disturbance in the investigated system. Second, only coarse conditions are required on reference trajectory and obstacles since their time derivatives are not necessarily to be available for feedback but those of the related literature muse be, while the reference trajectory is only required to be first rather than second order continuously differentiable. For this, a secure adaptive control framework is established by incorporating adaptive dynamic compensation mechanism into the backstepping procedure with the smart choice of adaptive law and the skillful injection of a barrier function. Consequently, a state‐feedback controller is explicitly designed which guarantees the obstacle‐avoidance of the robotic system while all the signals of the resulting closed‐loop system are bounded with system output practically tracking the reference trajectory. Finally, simulation results are provided for two specified robot systems to validate the effectiveness of the theoretical results.
This paper is devoted to the tracking control of a class of uncertain surface vessels. The main contributions focus on the considerable relaxation of the severe restrictions on system uncertainties and reference trajectory in the related literature. Specifically, all the system parameters are unknown and the disturbance is not necessarily to be differentiable in the paper, but either unknown parameters or disturbance is considered but the other one is excluded in the related literature, or both of them are considered but the disturbance must be continuously differentiable. Moreover, the reference trajectories in the related literature must be at least twice continuously differentiable and themselves as well as their time derivatives must be known for feedback, which are generalized to a more broad class ones that are unknown and only one time continuously differentiable in the paper. To solve the control problem, a novel practical tracking control scheme is presented by using backstepping scheme and adaptive technique, and in turn to derive an adaptive state-feedback controller which guarantees that all the states of the resulting
This paper is devoted to the tracking control of a class of uncertain surface vessels. The main contributions focus on the considerable relaxation of the severe restrictions on system uncertainties and reference trajectory in the related literature. Specifically, all the system parameters are unknown and the disturbance is not necessarily to be differentiable in the paper, but either unknown parameters or disturbance is considered but the other one is excluded in the related literature, or both of them are considered but the disturbance must be continuously differentiable. Moreover, the reference trajectories in the related literature must be at least twice continuously differentiable and themselves as well as their time derivatives must be known for feedback, which are generalized to a more broad class ones that are unknown and only one time continuously differentiable in the paper. To solve the control problem, a novel practical tracking control scheme is presented by using backstepping scheme and adaptive technique, and in turn to derive an adaptive state-feedback controller which guarantees that all the states of the resulting closed-loop system are bounded while the tracking error arrives at and then stay within an arbitrary neighborhood of the origin. Finally, simulation is provided to validate the effectiveness of the proposed theoretical results.
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