Image Number 7 for United States Patent #5195028.
A PI type 2DOF controller comprises setpoint filter for receiving a setpoint value, and outputting a control setpoint value, the setpoint filter having a transfer function which follows the setpoint value, and is expressed by the following formula: ##EQU1## where T.sub.I : an integral time, S: a Laplace operator, .alpha.: a constant which can be set between 0 and 1, and .beta.: a constant which can be set between 0 and about 10, deviationcalculating portion for calculating a deviation between the control setpoint value and a control value fed back from a controlled system, control operation portion for receiving the deviation, executing at least a PI (P: proportional, I: integral) control operation, and outputting a manipulative variable, and applying portion for applying the manipulative variable to the controlled system.
