Gun-launched rolling projectile actuator

An actuator system for controlling the external fins on a gun-launched projectile to control the flight path of the projectile. These actuator systems include an electric motor having a rotor and output shaft which is driven between travel limits that are less than 180 apart (less than 90 in either direction from a central rest position). Coupling from the motor shaft to the control shaft for the external fins is via a coupling between an eccentric ball on the motor shaft and an eccentric receptacle member on the fin shaft. As the angle of the motor shaft varies, the eccentric ball slides in a slot in the fin coupling member, causing the fin shaft angle to vary correspondingly. In another embodiment, the eccentric ball for controlling the fin shaft angle is mounted on a link arm that is coupled to the motor shaft, thereby permitting the motor to be mounted off the projectile axis and thus accommodating a shortened space in the projectile required for the actuator system and associated power supply.