Input-to-State Constrained Safety Zeroing Control Barrier Function and Its Application to Time-varying Obstacle Avoidance for Electric Wheelchair

Abstract

The safety guarantee of a control system under input disturbances is challenging. In this paper, we introduce an input-to-state constrained safety zeroing control barrier function (ISCSf-ZCBF) and propose an ISCSf-ZCBF-based human assist controller to ensure the safety of a human-operated system with unknown bounded input disturbances. The proposed human assist controller ensures not only safety but continuity and minimal intervention, which are suitable properties for human assist control. Then, we employ an ISCSf-ZCBF to achieve time-varying obstacle avoidance for an electric wheelchair by regarding an estimation error of obstacle velocity as an input disturbance. Finally, we experimentally confirm the effectiveness of the proposed controller.