Patent ID: 7216006

Claim:
A control system for a plant, including a sliding mode controller for controlling said plant with a sliding mode control, wherein said sliding mode controller includes: switching function value calculating means for calculating a value of a switching function defined as a linear function of a deviation between an output of said plant and a control target value; equivalent control input calculating means for calculating an equivalent control input that contributes to constraining a deviation state quantity which is defined based on the deviation between the output of said plant and the control target value, on a switching straight line on which the value of the switching function becomes zero; reaching law input calculating means for calculating a reaching law input that contributes to placing the deviation state quantity onto the switching straight line; control input calculating means for calculating a control input to said plant by adding at least the equivalent control input and the reaching law input; stability determining means for determining whether or not the sliding mode control is stable; and stabilizing means for reducing an absolute value of the equivalent control input when the sliding mode control is determined to be unstable.