A submersible robot developed by Planys, a start up nurtured by IIT Madras Incubation Cell is solving challenges in inspection of marine structures around the world including bridges, dams, ports, ships and submarines. Valuated at 15 million dollars, NDTV's Sam Daniel spoke to Prof Prabhu Rajagopal, a co-founder on their innovation and on Chennai becoming a hub for deeptech start ups.