Str Function (Torque Monitoring Function) - Mitsubishi Electric MELFA CR750 Series Instruction Manual

4 Safety monitoring function
4.3.6

STR function (Torque monitoring function)

(1) Overview
The function calculates a presumed torque based on the robot movement, defines an allowable torque width
around the presumed torque, and monitors whether the actual torque (torque feedback) is within the
allowable width. If the torque feedback exceeds the allowable torque width, error H221n (n is a joint axis
number) occurs and the robot turns the servo OFF to stop.
(2) Starting the STR function
The STR function is started when the monitoring mode is switched from Mode1 to Mode 2/3/M.
For example, when the DSI1 signal is turned OFF in Mode 1 and the mode is switched to Mode 2 after the
reaction time passes, the torque width monitoring is started. During the torque width monitoring, the function
monitors the difference between the presumed torque and the torque feedback to see if it is within the
allowable torque width. When the DSI1 signal is turned ON, the mode is returned to Mode 1 after the reaction
time passes and the torque width monitoring is ended.
(3) Switching the allowable toque width
An allowable torque width can be set for each monitoring mode. When the monitoring mode is switched, the
allowable width
STRTRQ2/STRTRQ3/STRTRQM.
Monitoring mode
Mode 2
Mode 3
Mode M
The allowable torque width monitoring is performed by switching the monitoring mode as follows.
When the DSI1 signal is turned OFF in Mode 1 and the mode is switched to Mode 2, the allowable torque
4-40 Safety monitoring function
is switched accordingly.
Parameter for the setting of
the allowable torque width
STRTRQ2
STRTRQ3
STRTRQM
Set the allowable width in the parameter