A wheelchair type mobile robot taking environmental disturbance into account

Abstract

Both human and robot will carry out a task which is not realizable by only each of them. In particular, a human recognizes environment and reflects to trajectory planning well. On the other hand, the robot generates the controlled force more than a human. In this paper, the best combination of human ability and robot capacity is considered. Based on the force commands from a human, a robot supports it. A reaction force estimation observer is implemented in the robot to detect environmental disturbance. Environmental disturbance is classified into the mode of translational direction and rotational direction. As a result, the adaptive force control in every mode is realized. External force is classified into the mode in frequency. The DC component of the external disturbance is a steady state force from the environment such as friction. High frequency of external disturbance might be a collision with an obstacle. This high frequency component will be relaxed by compliance control. Cooperation of human and robot is realized through force control. Three components including force command by human, DC component of external disturbance and high frequency of external disturbance are integrated to generate a force command to a robot. This force control is realized in each mode. The proposed method is applied to a wheelchair. As a result, operation and ride quality are improved. The numerical and experimental results show the viability of the proposed method.