Abstract
A number of unmanned small-size helicopters are widely used for industrial applications in recent years. This study focuses on a sytem of a small-size helicopter with a suspended load. Since vibration of the load have a bad effect on the safety flight, it is necessary to suppress the vibration. Thus purpose of this study is to develop a vibration control method for the system. Additionally, we demonstrate a control system design method. We applied delayed feedback control to the system in order to suppress the vibration by measuring angles of the load without state estimators. A limitation of the control is that the controller is difficult to design because it is the nonlinear control method. We designed the optimum delayed feedback controller by defininf a simple model and describing root loci of the system by using Pade approximation. The effectiveness of the present method was verified by flight tests. The results indicate that the method can be applied regardless of its cable length.
