MIR 1350 - Safety Stop Procedures

10. Safety-related functions and interfaces
MiR1350 User Guide (en) 05/2022 - v.1.2 ©Copyright 2021-2022: Mobile Industrial Robots A/S. 134
10.12 Safety stop
There are two pairs of contactors used to stop MiR1350: the STO (Safe Torque
Off) contactors and the dynamic brake contactors. These are controlled by the
safety PLC and are used when the robot goes into Protective or Emergency stop.
The following processes occur to stop the robot safely:
1. The safety PLCfirst turns off the STOcontactors so power is cut from the
motors.
To ensure that the STOcontactors switch states as expected,
there is a feedback circuit that connects to the safety PLC to verify
that the contactors switch to the correct state. When the robot is
starting up, the feedback circuit and STOcontactors are checked
before allowing the robot to be operated.
2. The safety PLCturns off the dynamic brake contactors to bring the robot to a
stop.
3. The safety PLCmonitors data from the motor encoders to determine whether
the robot has stopped within the expected amount of time.
4. Once the robot has stopped, the mechanical brakes are engaged to keep the
robot in place, similar to the parking brake in a car.
The mechanical brakes are only intended to engage when the robot has stopped.
Only when the dynamic brake function does not stop the robot within the
expected amount of time are the mechanical brakes engaged to stop the robot
while it is in motion. This is considered an emergency situation where the
dynamic brakes have failed, and an error is reported in the robot interface. This
can occur, for example, if the robot drives on surfaces that are not within
specifications or the load on the robot does not fulfill the payload
specifications—see Payload distribution on page239.