Observer Design for Estimating Support Force Applied by a Human Operator of a Biped Robot

The recognition of a robot operator’s intention/command is important in human-robot collaboration systems. This paper presents a novel approach to estimating the human operator’s force applied to a robotic system. In our previous study, we proposed a human-operated biped robot for transporting objects on rough terrain, steps or stairs. In this paper, we consider a new control system for the proposed robot, which enables the estimation of the support force applied by a human operator. The dynamics of the proposed robot are modeled by assuming that a support force applied by an operator is considered as a disturbance to each joint. The observer was designed to estimate the disturbance based on a high-gain observer; it was proven that the observer could estimate the disturbance with sufficient accuracy. Simulation results show that the observer successfully estimated the support force as a disturbance even though the disturbance property was completely unknown. In this study, the proposed biped robot system with the observer was expected to provide support to human operators for the cooperative transportation of objects up the stairs.