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This paper proposes a novel control framework for handling (potentially coupled) multiple time-varying output constraints for uncertain nonlinear systems. First, it is shown that the satisfaction of multiple output constraints boils down to ensuring the positiveness of a scalar variable (the signed distance from the time-varying output-constrained set's boundary). Next, a single funnel constraint is designed properly, whose satisfaction ensures convergence to and invariance of the time-varying output-constrained set. Then a robust and lowcomplexity funnel-based feedback controller is designed employing the prescribed performance control method. Finally, a simulation example clarifies and verifies the proposed approach.

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The trajectory tracking problem of a free-floating manipulator with dynamical uncertainties and stochastic input disturbances is solved in this study. First, the free-floating manipulator is mapped to a conventional fixed base dynamically equivalent manipulator. Then, by using the well-known properties of a revolute joint manipulator and taking into account the random disturbances with unknown power spectral density in control inputs, an adaptive controller scheme is developed. The proposed technique uses the exponential practical stability concept which guarantees that the tracking error and its derivative converge to an arbitrarily small neighborhood of zero by appropriate tuning of the controller’s parameters. It is noteworthy that the proposed controller does not need any physical parameters of the robot. Simulation studies demonstrate the effectiveness and capability of the proposed method for trajectory tracking in the presence of unknown stochastic input disturbances and dynamical uncertainties.