Low-complexity tracking control for high-order uncertain nonlinear systems with hard and soft constraints

This paper investigates the tracking problem under hard and soft output constraints for high-order uncertain nonlinear systems with unknown rational powers. In practical use, safety specifications are often seen as hard constraints which always appears in the form of constant constraints and soft constraints can be regarded as prescribed performance for tracking. First, we introduce an online funnel planning method which can generate a constraint consistent funnel (CCF) which usually gives hard constraints top priority, and soft constraints are fulfilled only when they don’t conflict with the hard constraints. Moreover, through the avoidance of employing fuzzy adaptive technology and tackling the problem of differential explosion, a control scheme with low-complexity has been implemented, maintaining the tracking error within the CCF. Ultimately, simulation results are offered to demonstrate the validity of the proposed scheme.