Abstract-This letter presents a new notion of input-tostate safe control barrier functions (ISSf-CBFs), which ensure safety of nonlinear dynamical systems under input disturbances. Similar to how safety conditions are specified in terms of forward invariance of a set, input-to-state safety (ISSf) conditions are specified in terms of forward invariance of a slightly larger set. In this context, invariance of the larger set implies that the states stay either inside or very close to the smaller safe set; and this closeness is bounded by the magnitude of the disturbances. The main contribution of the letter is the methodology used for obtaining a valid ISSf-CBF, given a control barrier function (CBF). The associated universal control law will also be provided. Towards the end, we will study unified quadratic programs (QPs) that combine control Lyapunov functions (CLFs) and ISSf-CBFs in order to obtain a single control law that ensures both safety and stability in systems with input disturbances. Index Terms-Safety critical control, barrier functions, input-to-state safety, autonomous systems.
The notion of input-to-state CBFs that ensured the safety of nonlinear systems under arbitrary input disturbances was introduced in REF , and safety was characterized in terms of the invariance of a set whose computation depended on the magnitude of the disturbance.
Input-to-State Safety With Control Barrier Functions
IEEE Control Systems Letters 3.1 (2019), pp. 108-113. ISSN: 2475-1456
Mathematics Computer Science