For a control system operated by a human, human assist control to avoid accidents attracts much attention in recent years. In this paper, we propose a novel definition of a control barrier function and a human assist control law with the proposed control barrier function. This paper proves that the proposed human assist control guarantees the safety of the control system under the human operation. Moreover, the paper shows that the control is the minimum of all safe inputs and a continuous function of both state and human inputs. The effectiveness of the proposed method is confirmed by computer simulation and experiments of a four-wheeled mobile robot.
In a modern aging society, electric wheelchairs are an essential means of transportation for the elderly. However, human operation errors of the electric wheelchair cause some accidents. For a control system operated by a human, human assist control to avoid accidents attracts much attention in recent years. For this problem, Nakamura et al. have proposed a relaxed control barrier function and a human assist control law. However, considering the operability and safety, it was difficult to apply the proposed human assist control to an electric wheelchair. In this paper, we propose a novel human assist control law that can consider an assist profile function based on a relaxed CBF. We aim to design human assist control law that can be applied to electric wheelchairs. The effectiveness of the proposed control method is confirmed by simulations and actual experiments using an electric wheelchair.
Human assist control of a control system driven by a human operator attracts much attention, and we have proposed a human assist control strategy has been proposed 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 this paper, we introduce a time-invariant graph space as 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. Finally, we confirm the effectiveness of the proposed method by computer simulation.