A robot (4) to bolt down a series of nut bolts (5) in a joint circular flange connection (18) of a wind turbine (1), which robot (4) comprises at least two wheels (12) and a drive (8) to transport the robot (4) along the series of nut bolts (5) and a tool (7) to bolt down a nut bolt (5) with a predefined torque and a position sensor (11) to position the tool (7) above the nut bolt (5) to be bolted down and a robot control system (17) to control the tightening process and document parameters relevant for the stability of each bolted down nut bolt (5).
