A design method of digital robust speed servo system considering output saturation

When a robust servo system having an integral element has a large error input, it often reveals windup phenomena caused by output saturation. It is very difficult for a strictly proper and high-order controller to avoid having windup phenomena caused by output saturation. This paper newly proposes the digital robust speed servo system with a complete algorithm for consideration of output saturation. The proposed algorithm completely considers the output saturation of a robust speed controller connected to a PI current controller in series. Moreover, this method can be applied to both a PI speed controller and an H-infinity speed controller. The experimental results show that a robust speed servo system using the proposed algorithm has a good and stable response for a large step speed command. (C) 2000 Scripta Technica.