Abstract
The low stiffness due to air compressibilty makes it difficult to control a pneumatic robot accurately. In order to improve its control performance, we propose a robust control scheme using the disturbance observer comprising the plant reference model. The disturbance observer estimates both the variations of plant parameters and disturbances based on the control input and the joint angular velocity. The proposed control scheme can decrease the influence of disturbances by means of the feedback of estimated disturbance. Its availability is investigated through simulations and experiments for the robot arms with two joints.
The obtained results can be summarized as follows: 1) To construct the disturbance compensation circuit, the static compensator is used to avoid the nonproper problem. As results, the control system can be easily designed. Further, it can attain the nearly equivalent control performance to which from the dynamic compensator. 2) The proposed control scheme can decrease the influence of not only external force and friction but also interaction force between joints. 3) The positioning perfrmance of robot arms can be improved owing to the effect of disturbance observer.
