Application of discrete-time quantized data controllers to systems with disturbances

In a recent paper, a new method for the digital control of a continuous-time system based on a table look-up technique was presented. This digital controller is called a discrete-time quantized data (DTQD) controller. In order to minimize the number of table entries, a grid embedding process is proposed. This control technique proved successful when applied to the regulator problem. However, when a DTQD controller using the grid embedding process is applied to a continuous-time system with additive disturbances, the performance of the DTQD controller degraded, causing oscillations and possible limit cycle phenomena. In this paper, the grid embedding process is replaced with a continuous scaling process. The continuous scaling process retains the advantages of the grid embedding process in reducing the number of table entries. In addition, it reduces the amount of oscillation in the system response when disturbances are present.