Patent ID: 7366576

Claim:
A device for controlling the position of a driven member of a machine tool in accordance with full closed loop control, the device comprising: a position control portion which generates a speed instruction in correspondence with a position instruction; a speed control portion which generates a thrust instruction in correspondence with the speed instruction in accordance with a proportional integral control; a driving member which drives the driven member in correspondence with the thrust instruction; a first detecting device which detects a driving state amount of the driving member; a second detecting device which detects a driven state amount of the driven member; a computing portion which computes an integrated feedback value in accordance with a function in which the speed and position of the driving member and the speed and position of the driven member are independent variables, wherein the speed and position of the driving member are obtained based on the detected driving state amount and the speed and position of the driven member are obtained based on the detected driven state amount; and a compensating portion which compensates the thrust instruction with the integrated feedback value, wherein the computing portion determines the integrated feedback value by multiplying each of the speed of the driving member, the position of the driving member, the speed of the driven member, and the position of the driven member by a predetermined feedback coefficient and adding the multiplied values together.