A control system may perform functions including (i) storing data indicating an association between an optical identifier and a first robot, (ii) sending, to the first robot, data encoding the optical identifier for display by the first robot, and (iii) after sending the data encoding the optical identifier, sending, to a second robot, the data indicating the association between the optical identifier and the first robot. In some examples, the first robot may receive, from the control system, data encoding a second optical identifier of the first robot so that the first robot may display the second optical identifier instead of the first optical identifier. In some examples, a first robot may capture an image of an indication of a priority status of a second robot and perform an action based on comparing a first priority status of the first robot to the second priority status of the second robot.