Positioning control system for moving element and laser drilling machine

A positioning control system for positioning a moving element on a basis of position command data, said positioning control system being provided with a feedback loop, comprising:

• a loop gain modifier for changing an existing coefficient α of loop gain at a discrete time in a constant sampling cycle, wherein first a new correction value Mn is obtained from the following formula:
• Mn=M+(Omax−NOv−Umax+NUv)·KP
• where M is a stored correction value, Omax is a measured maximum overshoot, Umax is a measured maximum undershoot, NOv is a predetermined nominal overshoot, NUv is a predetermined nominal undershoot, and KP is a coefficient;
• and then
• the existing coefficient α of the loop gain is replaced changed by calculating a new coefficient α with the new correction value Mn from the following formula:
• α=1+Mn;
• wherein said loop gain modifier changes the existing coefficient α of the loop gain when an absolute value s of the position command data is H≧s≧h, where h is a predetermined first acceptance value, and H is a predetermined second acceptance value, but not when the absolute value s of the position command data is not in said range.