fig4 shows how steering commands are generated in a down hole closed loop control system according to some embodiments of the invention in particular fig4 shows the down hole closed loop control system 10 according to some embodiments of the invention initial surface input data 11 which comprise start co ordinates and planned bore hole trajectory may be input into target position means 12 together with continuous measured bore path length updates 13 surface to rotary steerable system the target position means may generate target direction and or position information as a function of bore hole path length this information may then be input into a difference means 14 together with ins direction and or position estimate information from the ins 15 the difference between the planned direction and or position and actual direction and or position may then be input into well bore axes resolution means 16 the well bore axes resolution means may then resolve the direction and or position differences into well bore axes this information may then be fed into steering command generation means 17 which generates steering commands to pass to the rotary steerable tool bend unit 18 in the rotary steerable tool 19 the rotary steerable tool may incorporate an inertial measurement unit 20 and is connected to a drill bit 21 fig5 shows how steering commands are generated in a surface control system with possible manual intervention according to some embodiments of the invention fig5 shows a system in some embodiments of the invention in which the closed loop control system is located.