AbstractA novel approach for the design of a discrete‐time sliding mode controller is presented showing that the dynamics of a sliding‐mode state‐feedback controller can be designed using a singular LQR approach. The weighting of the control signal is set to zero and dead‐beat behaviour for the sliding mode reaching dynamics is achieved. The reaching dynamics are modified when the states are a significant distance away from the sliding surface to avoid any high magnitude control action due to the partial dead‐beat approach. The control law also takes into account the constraints on the actuator amplitudes and a stability analysis is presented using a discrete‐time version of the Popov criterion.The control approach is demonstrated in conjunction with a recently developed large‐span track‐seeking and track‐following method for dual‐stage actuator systems in a hard disk drive (HDD). It is shown how the discrete‐time sliding mode control scheme can be incorporated into the observer‐based control system for the secondary actuator. Superior performance for the track‐seeking and track‐settling process is demonstrated using an existing practical set‐up of a dual‐stage HDD servo system. Copyright © 2007 John Wiley & Sons, Ltd.