Time-varying Control Barrier Function and Its Application to Environment-Adaptive Human Assist Control

Abstract

Human assist control for a control system driven by a human operator attracts much attention, and we have proposed a human assist control strategy by using a control barrier function (CBF). However, the method is valid only for time-invariant environments; we cannot apply the method to a moving obstacle avoidance problem of a vehicle. In fact, the time-varying state constraint problem is a difficult problem. In this paper, we consider a time-invariant graph space for a time-varying state space. Then, we propose a time-varying CBF and human assist control based on the time-varying CBF for given time-varying environments. Moreover, we propose environment-adaptive human assist control for unknown environments. Finally, we confirm the effectiveness of the proposed method by computer simulation.