The adaptive control for a retrofit traditional milling machine

In this paper, the control plant is a traditional lead screw actuated milling machine table which has been retrofitted with DC servomotor control. This old-fashioned machining table has nonlinear time-varying behavior owing to the effects of irregular Coulomb friction of the sliding surface and obvious backlash. Traditional digital controllers are difficult to implement in this plant. It also cannot assure the stability problem of the closed loop system. Here, a stably convergent one-step ahead adaptive control method is proposed for this machining table. Experimental results show that this control method has reasonable performance of stability, transient response, tracking accuracy and robustness under the influence of time delay of the simple motor driver and 1 mm backlash of each axis.