An end effector is removably connected to a robot arm under sterile conditions with an arm mount module configured to be connected to the robot arm, and an arm drape module configured to be removably connected to the arm mount module by a first locking mechanism. A third module may be configured to be removably connected to the arm drape module by a second locking mechanism. A sterile hand drape module may be configured to be removably connected to the arm drape module by the second locking mechanism; and a hand mount module may be configured to be removably connected to the hand drape module by a third locking mechanism, and to be connected to the end effector or the hand mount module is the end effector itself. A transmission pathway for signals, electrical energy, or mechanical energy is provided between the robot arm and the end effector.