Force feedback in large, immersive environments is provided by device
which a gyro- stabilization to generate a fixed point of leverage for the
requisite forces and/or torques. In one embodiment, one or more
orthogonally oriented rotating gyroscopes are used to provide a stable
platform to which a force-reflecting device can be mounted, thereby
coupling reaction forces to a user without the need for connection to a
fixed frame. In one physical realization, a rigid handle or joystick is
directly connected to the three-axis stabilized platform and using an
inventive control scheme to modulate motor torques so that only the
desired forces are felt. In an alternative embodiment, a reaction sphere
is used to produce the requisite inertial stabilization. Since the sphere
is capable of providing controlled torques about three arbitrary,
linearly independent axes, it can be used in place of three reaction
wheels to provide three-axis stabilization for a variety of space-based
and terrestrial applications.