Output-Positive Adaptive Control of Hyperbolic PDE-ODE Cascades

In this paper, we propose a new adaptive Control Barrier Function (aCBF) method to design the output-positive adaptive control law for a hyperbolic PDE-ODE cascade with parametric uncertainties. This method employs the recent adaptive control approach with batch least-squares identification (BaLSI, pronounced "ballsy") that completes perfect parameter identification in finite time and offers a previously unforeseen advantage in safe control design with aCBF, which we elucidate in this paper. Since the true challenge is exhibited for CBF of a high relative degree, we undertake a control design in this paper for a class of systems that possess a particularly extreme relative degree: $2\times2$ hyperbolic PDEs sandwiched by a strict-feedback nonlinear ODE and a linear ODE, where the unknown coefficients are associated with the PDE in-domain coupling terms and with the input signal of the distal ODE. The designed output-positive adaptive controller guarantees the positivity of the output signal that is the furthermost state from the control input as well as the exponential regulation of the overall plant state to zero. The effectiveness of the proposed method is illustrated by numerical simulation.