  This work provides formal safety guarantees for control systems with
disturbance. A disturbance observer-based robust safety-critical controller is
proposed, that estimates the effect of the disturbance on safety and utilizes
this estimate with control barrier functions to attain provably safe dynamic
behavior. The observer error bound - which consists of transient and
steady-state parts - is quantified, and the system is endowed with robustness
against this error via the proposed controller. An adaptive cruise control
problem is used as illustrative example through simulations including real
disturbance data.
