Funnel Control Under Hard and Soft Output Constraints (extended version)

TL;DR

This paper introduces a novel funnel control approach that manages time-varying hard and soft output constraints, ensuring safety and performance in uncertain nonlinear systems through an online planning scheme and robust control design.

Contribution

It presents an innovative online funnel planning method combined with a robust funnel-based controller for uncertain nonlinear systems with dynamic constraints.

Findings

Successfully maintains safety constraints in simulations.

Ensures output performance within planned funnels.

Demonstrates robustness against system uncertainties.

Abstract

This paper proposes a funnel control method under time-varying hard and soft output constraints. First, an online funnel planning scheme is designed that generates a constraint consistent funnel, which always respects hard (safety) constraints, and soft (performance) constraints are met only when they are not conflicting with the hard constraints. Next, the prescribed performance control method is employed for designing a robust low-complexity funnel-based controller for uncertain nonlinear Euler-Lagrangian systems such that the outputs always remain within the planned constraint consistent funnels. Finally, the results are verified with a simulation example of a mobile robot tracking a moving object while staying in a box-constrained safe space.