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Thank you for your purchasing of our Mitsubishi Electric industrial robots.
This document describes additional precautions relating to the specification in the
RH-6SH/12SH/18SH Series Standard Specification manual (BFP-A8416).
Please be sure to read this document before using the robot for thorough understanding of the
contents.
1. Overview
The RH-6SH/12SH/18SH series robots (below as "RH-SH") has improved the resolution of the
encoder that is attached to the motor, compared to the conventional RH-5AH/10AH/15AH series
robots (below as "RH-A").
Therefore, if the RH-A's robot programs you are currently using are applied to the RH-SH series
without any modification, the positioning time may prolong.
・If the FINE instruction is used in RH-A's robot program, and FINE setting values are used in
RH-SH's program without any modification.
* Since the setting values of the FINE instruction varies depending on the application and robot
program you are using, please adjust them according to the actual machine in use.
2. Description
(1) Improvement of Encoder's Resolution
To achieve higher accuracy and higher response control, the encoder resolution of the RH-SH
series has been changed from 8,192 pulses to 131,072 pulses, compared with the RH-A robots.
(2) Characteristics of the FINE Instruction
The FINE instruction specifies the completion of the positioning of an operation instruction by the
number of the feedback pulses. Therefore, if the pulse specification value of the FINE instruction is
reduced, positioning accuracy will improve but, on the contrary, there is a tendency that the time
it takes for positioning will prolong. (See Figure 1.)
(3) Will Using RH-A's Programs in RH-SH Without Any Modification Delay the Processing Speed?
If the robot programs used in the RH-A robots (especially ones that use the FINE instruction) are
applied to the RH-SH robots without any modification, there is a case where the time it takes to
complete positioning prolong excessively.
This delay is caused by the improvement of the encoder resolution and the characteristics of the
FINE instruction described above.
For example, assuming that if the FINE is used with setting value 1 in the RH-A robot, its physical
angle have a difference of 16 times, compared to the RH-SH robots. (*1)
(*1): The RH-A's accuracy is 16 times rougher.
Suppose if the response performance is the same, RH-SH robots will take longer until the
completion of positioning. However, because RH-SH robots have improved tracking
characteristic, it does not always mean delay.
It is necessary to make adjustments based on the FINE setting value (required positioning
accuracy) and positioning time (required tact) you are using.
Therefore, to utilize any robot program used in the RH-A series, adjust the FINE setting value by
checking the positioning accuracy and positioning time.
Precautions for Using the FINE Instruction
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