Electromagnetic guidance control by use of Kalman filter state estimation

A new type of linear motor for railways has been developed. This linear motor is supported by iron wheels, and its horizontal motion is controlled by the attractive force of electromagnets. It is difficult to achieve control of this motor by classical control theory. There are three reasons for this: (1) the attractive force is nonlinear for variation of air gap; (2) there is indefinite friction between rail and wheels; (3) the detecting signals of position, velocity and acceleration contain much noise The authors applied a disturbance observer and a feedforward method to compensate for nonlinearity and modeling errors of friction, etc. Also, a Kalman filter which estimates state variables was used with LQI control. This paper presents the system configuration and experimental results.<>