This study is concerned with flexible pneumatic cylinder. The cylinder can be used in the various fields such as life support, medical, welfare systems which require lightweight, high flexibility, and high cleanliness. However, the control of the cylinder is insufficient and then it is needed to improve its control performance for widening of applications of the cylinder. Therefore, we propose combination of disturbance observer, which has a function of model matching, and Smith compensator, which compensates time delay of the system, with conventional PI control. To evaluate the control performance of the proposed control, some experiments are carried out. As a result, it is confirmed that the control performance of the proposed control can be drastically improved. In particular, it can be seen that the proposed control is effective for time delay of the system. The flexible cylinder with the proposed control scheme will be used in rehabilitation devices in practice
