We will first move the wheels of the robot.

In URBI, all the motor's speed and the sensor's value in a robot are associated with variables. You can set the motor's speed or get the sensor's value by assigning or reading the values of the corresponding variables.

In the default server layout for the TriBot model, the left wheel is assigned to variable wheelL and the right wheel is assigned to wheelR ^[1]. The values of these variables control the corresponding wheel speed. First put the TriBot upside-down to avoid any accident, then you can move the left wheel just doing:

  wheelL.speed = 50;

Don't omit the semicolon at the end of the line, or the command will not be executed. You can also move the right wheel (a negative value is a move backward) :

  wheelR.speed = -50;

A group is also defined so that you can give orders to several motors at the same time. In our case, the group wheels contains both robot wheels. Setting wheels to a value will set both wheels to this value :

  wheels.speed = 0;

will stop both wheels.

The third motor of the TriBot is associated with the claw variable.