This note presents two methods to design an single-input/single-output integral variable structure system. Once an overall transfer function is selected, two simple ways are presented to determine the required switching surface and the control function. The proposed methods not only avoid transforming the original plant into a companion form, but also enable the resulting control system to achieve the asymptotic tracking for a step reference signal and disturbance rejection for a bounded disturbance signal simultaneously. Two examples are given to illustrate the effectiveness of the proposed methods.
