A robotic drive system (110) is operable to actuate robotic joints and other robotic applications. The drive system includes an arm carrier (140) having a central shaft and two or more arms (145a, b). The arms (145a, b) extend radially from the arm carrier (140), where each of the arms (145a, b) includes an arm shaft (142a, b) at a distal end of the arm. A ground gear train (150, 155a, 155b) is located at a ground side of the arms, and an output gear train (165a, 165b, 160) is located at an output side of the arms. The arm carrier may be driven by a motor input (120), driving the gear trains to generate a torque at an output coupling at the output gear train. The robotic drive system provides compact, high-gear, high-stiffness features for use in, for example, prosthetics, rehabilitation, and mobile robots.