| 摘要 |
PURPOSE:To reduce the size of a control part and to improve the precision of the positioning of a controlled system, by positioning the controlled system at a stop position with prescribed precision by performing inverting operation in a short time when the controlled system has the extent of movement close to an expected stop position. CONSTITUTION:A microcomputer 21 compares position data in an up/down counter 28 with expected-stop-position data in a preset memory 30 to control the rotation of a servomotor 2. For forward rotation control, an FF22 is set by a motor ON signal, and an FF23 is set by a forward-rotation signal; and a motor driver 26 turns the servomotor 2 forward to move a welding electrode. When the welding electrode approaches an expected stop position, it is discriminated to reach where inversion should be done, and the FF23 is reset in a short time by an inversion signal on the basis of inversion time data to reverse the motor 2. Whether count data indicating the current position of the short-time control is within the range of the stop-position-precision data in the memory 30 or not is checked, and when so, the movement of the welding electrode is stopped. |
