Patent ID: 7991486

Claim:
A process control apparatus comprising: a controller that generates a first manipulated value based on a setting value and a measured value; a plug-in disturbance-rejection controller that is designed by using parameters as in the following equation: { J ⁡ ( z - 1 ) = J x ⁡ ( z - 1 ) + J y ⁡ ( z - 1 ) ⁢ Q ⁡ ( z - 1 ) K ⁡ ( z - 1 ) = K x ⁡ ( z - 1 ) + K y ⁡ ( z - 1 ) ⁢ Q ⁡ ( z - 1 ) wherein J x ( z −1 )=1 , K x ( z −1 )=0, J y ( z −1 )= z −d B ( z −1 ) S ( z −1 ), K y ( z −1 )=−( S ( z −1 ) Ā ( z −1 )+ z −d R ( z −1 ) B ( z −1 )) and Q(z −1 ) is a solution of the equation: D p ( z −1 ) J ′( z −1 )− z −d B ( z −1 ) S ( z −1 ) Q ( z −1 )=1, wherein z −1 is a complex variable, d is a dead-time that is represented by a discrete time, J is a denominator polynomial of a discrete time model for the plug-in disturbance-rejection controller, J x is a design component of J, J y is another design component of J, K is a numerator polynomial of the discrete time model for the plug-in disturbance-rejection controller, is a design component of K, K y is another design component of K, O is a parameter polynomial that is to be computed, S is denominator polynomial of the discrete time model for a controller, R is a numerator polynomial of the discrete time model for the controller, D p is a denominator polynomial of the discrete time model for a disturbance generator, B is a numerator polynomial of the discrete time model combining a control target with a primary filter, Ā is a denominator polynomial of the discrete time model combining the control target with the primary filter, and J′ is a polynomial excluding D p from the denominator polynomial of the plug-in disturbance-rejection controller; the plug-in disturbance-rejection controller generating a second manipulated value; a machine as a control object that receives the first manipulated value and the second manipulated value, the machine measuring a value of a tangible object and generating the measured value; and a primary filter that establishes a feedback loop, the primary filter receiving the measured value from the machine, the primary filter compensating for a frequency band in which a gain is increased due to waterbed effects that are caused by the plug-in disturbance-rejection controller, the primary filter feeding an output back to the controller, the primary filter supplying the output to the plug-in disturbance-rejection controller.