Disturbance Observer-based Control for Raymond Mill Grinding Process

In the raymond mill grinding processes, high-accuracy control for the current of raymond mill is the key point to enhance the product quality and production efficiency. However, strong external disturbances, such as variations of ore hardness and ore size, always exist. It is not easy to make the current of raymond mill constant. Several control strategies have been proposed to control the grinding processes. However, most of them (such as PID and MPC) reject disturbances merely through feedback regulation and do not deal with the disturbances directly, which may lead to poor control performance when strong disturbances occur. To improve disturbance rejection, a control scheme based on PID and disturbance observer is put forward in this paper. The scheme combines a feedforward compensation part based on disturbance observer and a feedback regulation part using PID. The test results illustrate that the proposed method can obtain remarkable superiority in disturbance rejection compared with PID method in the raymond mill grinding processes.