There are various wireless communication technologies used in building IoT applications and RF (Radio Frequency) is one of them. nRF24L01 is a single-chip radio transceiver module that operates on 2.4 - 2.5 GHz (ISM band).
Robots are used in many sectors like construction, military, manufacturing, assembling, etc. Robots can be autonomous or semi-autonomous. Autonomous robots do not require any human intervention and can act on their own according to the situation.