Panasonic MINAS A4P Series - Manual (Page 140)

140
Outline of Full-Closed Control
What Is Full-Closed Control ?
In this full-closed control, you can make a position control by using a external scale mounted externally
which detects the machine position directly and feeds it back.. With this control, you can control without
being affected by the positional variation due to the ball screw error or temperature and you can expect to
achieve a very high precision positioning in sub-micron order.
Preparation for full-closed control
1) Wire the external scale referring to “Wiring to CN X7” in “System Configuration and Wiring” on page 40.
2) Set SV.Pr02 (control mode setting) to “6” (full-closed control). (Change becomes enabled after turning the
power supply on again.)
3) Specify each parameter according to “Cautions on Full-Closed Control” below.
Controller
Position
command
(Speed detection)
Position detection
External scale
Cautions on Full-Closed Control
A4P-series supports the external scale of a communication type. Execute the initial setup of parameters per
the following procedures, then write into EEPROM and turn on the power again before using this function.
1) Turn on the power after checking the wiring.
2) Check the values (initial) feedback pulse sum and external scale feedback pulse sum with the
console or with the setup support software, PANATERM ® .
3) Move the work and check the travel from the initial values of the above 2).
4) If the travel of the feedback sum and the external scale feedback pulse sum are reversed in positive
and negative, set up the reversal of external scale direction (SV.Pr7C) to 1.
5) Set up the external scale division ratio (SV.Pr78-7A) using the formula below,
We recommend 1/20 < = external scale division ratio < = 20.
If the external scale division ratio is set to a value smaller than 50/position loop gain (SV.Pr10,
18), control per pulse may not be performed. If the external scale division ratio is set to a larger
value, an operating noise may become large.
* If the design value of the external scale division ratio is obtained, set up this value.
6) Set up appropriate value of hybrid deviation excess (SV.Pr7B) in 16 pulse unit of the external scale
resolution, in order to avoid the damage to the machine.
* A4P-series driver calculates the difference between the encoder position and the external scale
position as hybrid deviation, and is used to prevent the machine runaway or damage in case of
the external scale breakdown or when the motor and the load is disconnected.
If the hybrid deviation excess range is too wide, detection of the breakdown or the disconnection
will be delayed and error detection effect will be lost. If this is too narrow, it may detect the normal
distortion between the motor and the machine under normal operation as an error.
* When the external scale division ration is not correct, hybrid deviation excess error (Err25) may
occur especially when the work travels long distance, even though the external scale and the
motor position matches.
In this case, widen the hybrid deviation excess range by matching the external scale division ratio
to the closest value.
External scale division ratio =
Total variation of external scale feedback pulse sum
Total variation of feedback pulse sum
=
SV.Pr78 x 2 SV.Pr79
SV.Pr7A