A steel plant control device includes a subtractor, a PI controller, a first-order lag controller, and an adder. In a band that is lower than a first frequency f1, a gain of the PI controller is higher than a gain of the first-order lag controller; in a band from the first frequency f1 to a second frequency f2, the gain of the first-order lag controller is higher than the gain of the PI controller; and in a band that is higher than the second frequency f2, the gain of the PI controller is higher than the gain of the first-order lag controller.

A steel plant control device includes a subtractor, a PI controller, a first-order lag controller, and an adder. In a band that is lower than a first frequency f1, a gain of the PI controller is higher than a gain of the first-order lag controller; in a band from the first frequency f1 to a second frequency f2, the gain of the first-order lag controller is higher than the gain of the PI controller; and in a band that is higher than the second frequency f2, the gain of the PI controller is higher than the gain of the first-order lag controller.

A feedback control apparatus includes: a detector configured to detect an output value based on a controlled object; a P control circuit including a differential amplifier circuit and an analog circuit, the differential amplifier circuit being configured to receive a detection value of the detector and a target value, the analog circuit being configured to output a P control component V.sub.P to an output of the differential amplifier circuit; an I control unit configured to output an I control component V.sub.I by integrating a deviation of the detection value from the target value by digital processing; and a driver element configured to be driven based on the P control component V.sub.P from the P control circuit and the I control component V.sub.I from the I control unit to control the controlled object.

An end effector can be removed to a target position and calibration loads can be reduced, even if there is an error in a kinematic operation in a robot main body and/or cameras. A positional deviation integral torque obtained by integrating a value corresponding to a positional deviation is applied to joints while being superimposed with torques based on angular deviations. If movements of the joints stop or are about to stop before the end effector reaches a target position due to an error in a kinematic operation, the positional deviation integral torque increases with time, to move said joints and move the end effector to the target position. Thus, the end effector can be reliably moved to the target position by the positional deviation integral torque, and calibration loads can be reduced.

A feedback control apparatus includes: a detector configured to detect an output value based on a controlled object; a P control circuit including a differential amplifier circuit and an analog circuit, the differential amplifier circuit being configured to receive a detection value of the detector and a target value, the analog circuit being configured to output a P control component V.sub.P to an output of the differential amplifier circuit; an I control unit configured to output an I control component V.sub.I by integrating a deviation of the detection value from the target value by digital processing; and a driver element configured to be driven based on the P control component V.sub.P from the P control circuit and the I control component V.sub.I from the I control unit to control the controlled object.