A force feedback mouse interface device connected to a host computer and
providing realistic force feedback to a user. The mouse interface device
includes a mouse object and a linkage coupled to the mouse that includes
a plurality of members rotatably coupled to each other in a planar
closed-loop linkage and including two members coupled to ground and
rotatable about the same axis. Two actuators, preferably electromagnetic
voice coils, provide forces in the two degrees of freedom of the planar
workspace of the mouse object. Each of the actuators includes a moveable
coil portion integrated with one of the members of the linkage and a
magnet portion coupled to the ground surface through which the coil
portion moves. The grounded magnet portions of the actuators can be
coupled together such that a common flux path between the magnet portions
is shared by both magnets. At least one sensor is coupled to the ground
surface that detects movement of the linkage and provides a sensor signal
including information from which a position of the mouse object in the
planar workspace can be determined.