Abstract
This paper presents a dual mode high speed position control, with high accuracy, of a Linear DC Motor (LDM). In our research, a linear encoder using magneto resistive effect element is used as the position detector and the dual mode control consists of seek and analogue controls. The seek control is a bang-bang control switched on a line in the phase plane, the gradient of which line is adaptively changed according to an initial position error of the LDM, so that the position error approaches zero in the shortest time. However, a sliding mode occurs owing to modelling errors of the LDM, so the true time optimal control can not be obtained.
This paper considers the condition under which a sliding mode occurs by our control and proposes a method of correcting the gradient of the switching line by repeating trial experiments to minimize the interval of the sliding mode, consequently our control has the control performance very near to the time optimal one. In a neighborhood of the origin in the phase plane, an analogue feedback control system is constructed to keep the LDM at the origin. Finally, experimental results prove that the proposed method is very effective to a high speed position control.
