  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 low-complexity funnel-based feedback controller is designed
employing the prescribed performance control method. Finally, a simulation
example clarifies and verifies the proposed approach.
