IAI America ERC - Manual (Page 121)

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Example) If the start signal for movement to position 2 is input while the actuator is moving to position 1
in the push & hold mode, the actuator will move to the position 10 mm from where it was when
the input signal was input.
No. Position Speed
0 * *
1 50 100
2
10 100
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(3) Cumulative errors due to repeated incremental moves
Position data is recognized only as a multiple of the minimum resolution. The minimum resolution is
determined by the lead and the number of encoder pulses. Therefore, a margin of error may occur
between the entered position value and the actual movement of the actuator. If an incremental move is
repeated, this error will accumulate.
The maximum error range for each actuator type is shown below:
ERC model Speed type Lead [mm] Maximum error range [mm]
Low speed 3 0.00375
Medium speed 6 0.0075
ERC -SA6
-RA54
-RA54GS
-RA54GD
High speed 12 0.015
Low speed 4 0.005
Medium speed 8 0.01
ERC -SA7
-RA64
-RA64GS
-RA64GD
High speed 16 0.02
Example) If an incremental move is repeated 10 times on an ERC-SA7/RA64 high-speed actuator, a
maximum error of 0.02 x 10 = 0.2 [mm] may generate with respect to the final position.
To eliminate these cumulative errors, an absolute command must be executed before the error tolerance is
exceeded.
(4) Ball screw accuracy
The accuracy of the ball screw used in the ERC conforms to C10 under the JIS standard.
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Command position
Start
Position complete
Speed
Actuator movement
Position 1 Position 2
Distance
10 mm