A robotic catheter manipulator assembly may include a support member including a catheter manipulation base and a sheath manipulation base movable relative to each other and to the support member. Each respective manipulation base may be releasably connectable to a catheter cartridge and a sheath cartridge. A drive mechanism may be provided for moving the catheter and sheath manipulation bases relative to each other and to the support member. The manipulation base or the cartridge may include a first element engageable with a complementary second element slidably engaged with the other one of the manipulation base or the cartridge for controlling movement of a component connected to the cartridge. The cartridge, for example, may be a transseptal cartridge, a catheter cartridge or a sheath cartridge, and the component may respectively be a surgically insertable device such as a transseptal needle, a catheter or a sheath.