Mitsubishi Electronics QD75P, QD75D Refer to the term Operation Pattern, Loop gain, Droop pulses

APPENDICES

MELSEC-Q

POSITION CONTROL POSITION LOOP MODE

This is mainly the control of position and dimension, such as in fixed-feed, positioning, numerical control, etc. This is always controlled with feed pulses. There is also speed control.

Drive units may differ, even when the same motor is used.

POSITION DETECTION MODULE

This is an abridged version of positioning. There are two types on MELSEC, the A1S62LS. This module has positioning and limit switch functions, and can use a total of 16 channels. The following drawing shows an example for 5 channels. A resolver is used in the positioning detection.

	0		4095
Positioning	High speed		ON
				ON
Positioning	Low speed
		ON			ON
Limit switch	LS1
				ON
Limit switch	LS2
				ON
Limit switch	LS3

This is one servo control mode used in positioning. It is a mode for carrying out position control. The other servo control modes are the speed loop mode for carrying out speed control, and the torque loop mode for carrying out torque control (current control).

	Servo amplifier			Servomotor
Droop pulses
Pulse train
Posi-	Speed	Cur-		M
tion		rent	Inverter
	control
control		control
		Current feedback
	Speed feedback
Position feedback			Interface	PLG

POSITIONING

Accurately moving the machine from a point to a determined point. The distance, direction, speed, etc., for that movement are designated by the user. Positioning is used in operations such as cutting sheets, drilling holes in plates, mounting parts on a PCB, and welding. Positioning is also used with robots.

POSITION LOOP GAIN

This is the ratio of the deviation counter droop pulses to the command pulse frequency.

Position	=	Command pulse frequency	(1/s)
loop gain		Droop pulses

The position loop gain can be set with the drive unit. Raise the gain to improve the stopping accuracy. However, overshooting will occur if the position loop gain is raised too far, and the operation will become unstable.

If the position loop gain is lowered too far, the machine will stop more smoothly but the stopping error will increase.

POSITIONING COMPLETE

Refer to the term "OPERATION PATTERN".

POSITIONING COMPLETE SIGNAL

This is a signal that occurs when the positioning is complete. A timer set beforehand starts when this signal is output, and the machine movement stops for that time.

When this signal turns ON, the positioning start signal turns OFF.

Dwell time

Positioning complete signal

Positioning Different type of work

Time

Appendix - 84