An active user interface system (100) includes a gimbal assembly that is configured as a dual-input/single-output differential mechanism. The differential mechanism implements a speed reduction from the inputs of the differential mechanism (132, 134) to the output of the differential mechanism. Speed reduction enables the maximum drive torque that is supplied to the user interface about one rotational axis to be N times greater than the maximum drive torque that is supplied to the user interface about another, perpendicular axis.