Disturbance Observer-Parameterized Control Barrier Function with Adaptive Safety Bounds

TL;DR

This paper introduces a disturbance observer-parameterized control barrier function that dynamically adjusts safety bounds based on external disturbances, enhancing robustness and safety in control systems.

Contribution

It proposes a novel adaptive safety bound mechanism using a disturbance observer, ensuring safety and robustness without relying on worst-case disturbance assumptions.

Findings

Demonstrated improved safety performance in cruise control simulations

Effectively managed safety bounds under varying road conditions

Maintained forward invariance despite observer errors

Abstract

This letter presents a nonlinear disturbance observer-parameterized control barrier function (DOp-CBF) designed for a robust safety control system under external disturbances. This framework emphasizes that the safety bounds are relevant to the disturbances, acknowledging the critical impact of disturbances on system safety. This work incorporates a disturbance observer (DO) as an adaptive mechanism of the safety bounds design. Instead of considering the worst-case scenario, the safety bounds are dynamically adjusted using DO. The forward invariance of the proposed method regardless of the observer error is ensured, and the corresponding optimal control formulation is presented. The performance of the proposed method is demonstrated through simulations of a cruise control problem under varying road grades. The influence of road grade on the safe distance between vehicles is analyzed and managed using a DO. The results demonstrate the advantages of this approach in maintaining safety and improving system performance under disturbances.