A second order discrete sliding mode observer for the variable structure control of a semi-batch reactor

This paper concerns the chattering elimination from discrete sliding mode observers. The dilemma chattering-precision, that characterizes the first order sliding mode observer in case of relatively large parameter variations and/or external disturbances, is discussed and the influence of the discontinuous term amplitude on the estimation performance is shown by a simulation example. The proposed second order discrete sliding mode observer is, then, introduced. The stability of a closed loop control system based on the proposed observer is analyzed. A real time application of the proposed observer incorporated into a 2-DSMC control loop of a chemical reactor is presented.

► The first order discrete sliding mode observer is characterized by a chattering-precision dilemma.
► The proposed second order discrete sliding mode observer resolves this problem.
► The stability of a closed loop control system based on the proposed observer is analyzed.
► A real time experimentation on a chemical reactor is presented.