抄録
Many kinds of electro-hydraulic servo systems are applied to rolling mills such as a hot strip mill, a cold strip mill and a seamless tube mill because of quick response, high power and high positioning accuracy. However when applying an electro-hydraulic servo system to a hot strip downcoiler, it was found that the controlled object has low natural frequency and is lightly damped so that stable control is very difficult. Optimal control theory has been recognized as a powerful tool for system synthesis in such a case. This paper first shows that the existing design method of optimal control is effective for designing an electro-hydraulic servo controller, in which the proper weighting matrices in the quadratic performance function can be determined directly from a physical model. A new design method is then proposed by which the state feedback gains can be obtained directly based on the characteristics of the controlled object. The effectiveness of the controller is demonstrated experimentally.
