Abstract: There is provided a servo system for controlling position of a sensor assembly (30) in a data readout and/or writing device (10, 500). The device (10, 500) includes: (a) two actuators (28, 36) for spatially actuating a structural assembly (22) and its associated sensor assembly (30, 530), the system further comprising: (b) a servo control unit (34, 600) in communication with the two actuators (28, 36) for controlling spatial movement of the structural assembly (22) and the sensor assembly (30, 530). The controlling means (34) is operable: (c) to apply substantially velocity feedback control to the actuators (28, 36) when the sensor assembly (30, 530) is substantially remote from a desired target position; and (d) to apply substantially position feedback control to the actuators (28, 36) when the sensor assembly (30, 530) is substantially spatially proximate to said target position.