Final answer:
The command that outputs messages from the robot controller to the computer screen is the 'print' command.
Step-by-step explanation:
The command that outputs messages from the robot controller to the computer screen is the print command. In most programming languages, including Python, the print command is used to display text or other information on the screen. Here is an example:
print('Hello, world!')
This will output the message 'Hello, world!' to the computer screen.