An apparatus which comprises a manipulandum that is configured as a surgical instrument; a closed loop linkage system which includes a first central member fixedly coupled to a first object coupling and a second central member fixedly coupled to a second object coupling, wherein the first and second object couplings are separately coupled to the manipulandum to allow the manipulandum to be moveable in a plurality of rotary degrees of freedom and an axial degree of freedom; a force feedback system is coupled to the linkage system, wherein the force feedback system selectively applies resistive forces to the manipulandum based on the position of the manipulandum with respect to one or more reference coordinates. In an embodiment, the force feedback system includes an actuator to provide a force to the manipulandum in at least one degree of freedom in response to signals received from a computer system.

Controlling haptic sensations from a vibrotactile feedback device connected to a computer. The vibrotactile device includes an actuator having a rotatable mass, and receives information, which causes a periodic control signal to be produced. The control signal controls the actuator to rotate the mass to induce a vibration in the device, where a magnitude and a frequency of the vibration can be adjusted independently of each other by adjusting the control signal. Vibration magnitude is based on control signal duty cycle, and vibration frequency is based on control signal frequency. Kinesthetic haptic effects can be output on the vibrotactile device by mapping the kinesthetic effect to a vibrotactile effect that causes vibrotactile forces to be output. The kinesthetic haptic effect can be a periodic or nonperiodic effect.

The invention is an apparatus for physically exchanging a force with a user in an environment local to the user. A connection element connects to a user's body member and a linkage between the connection element and ground. The linkage includes means for powering at least three independent freedoms of the connection element relative to ground and means for maintaining at least one independent freedom of the connection element relative to ground free of power. Up to three independent freedoms of the connection element may be maintained free of power, and up to five independent freedoms may be powered. Other aspects of the invention include a two actuator counter-balance for controlling a point on a link. The invention also includes apparatus for establishing a virtual, switch, which presents to the user the force and displacement relationship of a spring switch. Another embodiment is a virtual bristled brush, again which presents to the user the force and displacement relationship of such a brush, while also changing the virtual environment to reflect the user's changes in location.

A method and apparatus for controlling and providing force feedback using an interface device manipulated by a user. A microprocessor is provided local to the interface device and reads sensor data from sensors that describes the position and/or other information about an object grasped and moved by the user, such as a joystick. The microprocessor provides the sensor data to a host computer that is coupled to the interface device by a communication bus that preferably includes a serial interface. In a "host-controlled" embodiment, the host computer calculates force values using the sensor data and other parameters of a host application program and sends the force values to the local microprocessor, which directly provides the force values to actuators to apply forces to the user object. In a "reflex" embodiment, the host computer sends high level supervisory commands to the local microprocessor, and the microprocessor independently implements a local process based on the high level command for reading sensor data and providing force values to the actuators using sensor data and other parameters.