Three-degree-of-freedom control and its application to motion control systems

This paper proposes a Three-degree-of-freedom (Three-DoF) control that is extended from a Two-degree-of-freedom (Two-DoF) control. In a classical Two-DoF control, the command input response and the disturbance suppression characteristics can be determined independently. However, the disturbance suppression characteristic and the noise suppression characteristic have a trade-off relation. Thus, if the disturbance suppression property sets high, the noise suppression property becomes low, and vice versa. In Three-DoF control scheme, command input response, disturbance suppression, and noise suppression property can be determined independently. To realize above capability, the controlled plant is divided by utilizing its linearity and an additional controller is used. In this paper, the control system architecture and the controller design methodology are shown and its effectiveness are validated by position control simulations of a 1DoF DC motor model.