A high density actuator , comprising: a housing assembly composed of: a first housing element containing a motor stator ; and a second housing element containing a gear reduction mechanism in the form of a circular spline positioned inside the second housing element ; a rotational core being composed of: a motor rotor ; a transmission input in the form of a wave generator operatively connected to the motor rotor ; a transmission output in the form of a flex spline connected to the transmission input , the transmission output being positioned at the center of the gear reduction mechanism ; a torque transfer output operatively connected to the actuator transmission output ; characterized in that the motor rotor is configured to rotate freely around a center shaft via conical roller bearings positioned between the center shaft and the first housing element ; and in that the torque transfer output is furthermore operatively connected to the center shaft , which passes through the transmission output , rotational core and second housing element ; wherein the center shaft ensures proper radial and axial alignment between the housing assembly and the torque transfer output . a housing assembly composed of: a first housing element containing a motor stator ; and a second housing element containing a gear reduction mechanism in the form of a circular spline positioned inside the second housing element ; a rotational core being composed of: a motor rotor ; a transmission input in the form of a wave generator operatively connected to the motor rotor ; a transmission output in the form of a flex spline connected to the transmission input , the transmission output being positioned at the center of the gear reduction mechanism ; a torque transfer output operatively connected to the actuator transmission output ; characterized in that the motor rotor is configured to rotate freely around a center shaft via conical roller bearings positioned between the center shaft and the first housing element ; and in that the torque transfer output is furthermore operatively connected to the center shaft , which passes through the transmission output , rotational core and second housing element ; a first housing element containing a motor stator ; and a second housing element containing a gear reduction mechanism in the form of a circular spline positioned inside the second housing element ; a rotational core being composed of: a motor rotor ; a transmission input in the form of a wave generator operatively connected to the motor rotor ; a motor rotor ; a transmission input in the form of a wave generator operatively connected to the motor rotor ; a transmission output in the form of a flex spline connected to the transmission input , the transmission output being positioned at the center of the gear reduction mechanism ; a torque transfer output operatively connected to the actuator transmission output ; characterized in that the motor rotor is configured to rotate freely around a center shaft via conical roller bearings positioned between the center shaft and the first housing element ; and in that the torque transfer output is furthermore operatively connected to the center shaft , which passes through the transmission output , rotational core and second housing element ; wherein the center shaft ensures proper radial and axial alignment between the housing assembly and the torque transfer output . <EOS>