Abstract: In a position control system having force as a manipulated variable and position as a controlled variable, negative feedback of position and velocity is performed. Positive feedback of acceleration is performed through a first order lag circuit. Alternatively positive feedback of velocity is performed through a quasidifferential circuit. By the combination of negative and positive feedback, it is possible to stabilize vibration characteristics of the mechanism, which tends to make the control system stable, and to achieve position control with high gain, high response and high accuracy.

Abstract: A first servo system (31) which feeds back at least position and speed and a second servo system (32) which effects integral control by feeding back position are connected in series. A first signal obtained by multiplying the output of the integral controller of the second servo system by a first gain is added to the position feedback signal of the first servo system, while a second signal obtained by multiplying the input of the integral controller of the second servo system by a second gain is added to the speed feedback signal of the first servo system. In this way, feedback control is effected using one mutual position detector, thereby eliminating the dynamic interference between the first and second servo systems, and thus enabling the two servo systems to be activated simultaneously.