10. Safety-related functions and interfaces
MiR600 User Guide (en) 08/2021 - v.1.0 ©Copyright 2021: Mobile Industrial Robots A/S. 122
10.12 Safety stop
There are two pairs of contactors used to stop MiR600: 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 PLCfirst turns off the STOcontactors so power is cut from the motors.
To ensure that the STOcontactors 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 STOcontactors are checked before allowing the robot
to be operated.
2. The safety PLCturns off the dynamic brake contactors to bring the robot to a stop.
3. The safety PLCmonitors 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 page216.
10.13 Light indicators and speakers
The robot uses two types of light indicators to let people in the environment know what the
robot is currently doing or planning to do.
• Status lights
The LED light bands on all four sides of the robot use colors and light motion patterns to
signal the current status of the robot.
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