Robotics has many applications in many fields. It is not just electronics. Robotics integrates many fields such as Mechanical, Computer science and Electrical. (Mechatronics too)
E&I (Subbranch of EEE), is the answer to your question because instrumentation refers to industrial processes and techniques for industrial automation. Is ECE inclusive of more communication parts like satellite communication and mobile communication? Communication is also important in data transfer.
Another thing is that Robotics will not be included in any one branch’s curriculum. Although Robotics and Automation may be included in one of the above branches, such as EEE, EIE, CSE,Mech, it will not be a subject that a layman would consider robotics. It is industrial robots.
Robotics is a field that you may be interested in. You can pursue it as a Masters degree after you have completed your B.Tech/B.E in one of the above-mentioned branches.
Another thing you can do is learn robotics through projects.