Robust Non-Fragile Fault Tolerant Control for Ensuring the Safety of the Intended Functionality of Cooperative Adaptive Cruise Control

Abstract

Cooperative adaptive cruise control (CACC) has the potential to significantly improve road safety, highway throughput and reduce fuel consumption. However, the safety of the intended functionality (SOTIF) of CACC that focuses on unreasonable risks related to performance limitations has not been addressed. Moreover, various unknown uncertainties, disturbances, and controller perturbations present in the road environment make the guarantee of SOTIF for CACC a more challenging problem. This study presents a robust non-fragile fault tolerant control (RNFTC) strategy as a quantitative risk reduction method for ensuring SOTIF of CACC with system uncertainty, multisource disturbances, and controller perturbations. First, an intermediate based robust estimation method is proposed to estimate the performance limitations of perception and actuation, system states, and matched disturbances, simultaneously. Second, a robust non-fragile <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{H}_{\infty }$ </tex-math></inline-formula> FTC method is proposed to accommodate the simultaneous presence of performance limitations and disturbances. Third, theorems for solving optimal estimator and controller gains of the proposed RNFTC are derived in terms of linear matrix inequalities (LMIs). The requirements for CACC system stability, robustness, non-fragile and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{H}_{\infty }$ </tex-math></inline-formula> performances under the proposed RNFTC are analyzed using Lyapunov theory. Finally, a series of comparative simulations with the CACC system are conducted to demonstrate the effectiveness and superiority of the proposed RNFTC method on ensuring SOTIF of CACC under unknown uncertainties, disturbances, and perturbations.