A wheelchair type mobile robot taking environmental disturbance into account

Both human and robot will carry out a task which is not realizable by only each of them. In particular, human recognizes environment and reflects to trajectory planning well. On the other hand, robot generates the controlled force more than human. In this paper, the best combination of human ability and robot capacity is considered. Based on the force commands from human, robot supports it. Reaction force estimation observer is implemented in 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. DC component of external disturbance is steady state force from environment such as friction. High frequency of external disturbance might be a collision with 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 robot. This force control is realized in each mode. The proposed method is applied to wheelchair. As a result, operationality and ride quality are improved. The numerical and experimental results show viability of the proposed method.