Method and apparatus for providing damping force feedback

A method for interfacing motion of an object with a host computer, said host computer updating a graphical environment in response to user manipulation of said object and commanding said apparatus to generate force feedback sensations in coordination with events within said graphical environment, the method comprising

• providing an object having a degree of freedom with respect to a ground surface, said object being grasped by a user;
• sensing positions of said object along said degree of freedom with respect to said ground surface using a sensor and producing electrical sensor signals therefrom, said electrical sensor signals being received by said host computer;
• and
• creating a passive damping resistance to movement of said object along said degree of freedom, said passive damping resistance being created by the passive flow of a fluid through an orifice caused by said user's manipulation of said object, wherein said passive damping resistance is changed by adjusting an amount of said passive flow of said fluid through said orifice in response to signals received from said host computer.

A computer interface device for use with a host computer updating a graphical simulation in response to user manipulation of said interface device, said host computer commanding said computer interface device to generate force feedback sensations in coordination with events within said graphical simulation, said interface device comprising:

• a user object grasped by a user;
• a support mechanism which supports said user object while allowing a degree of freedom of motion of said object with respect to a grounding surface;
• an actuator for providing resistance to motion of said user object along said degree of freedom of said user object, said actuator including a grounded portion and a non-grounded portion, wherein said grounded portion of said actuator remains stationary with respect to said grounding surface, and wherein said resistance to motion is varied by said actuator in response to commands from said host computer;
• a coupling mechanism provided between said actuator and said user object, said coupling mechanism allowing play between said user object and said non-grounded portion of said actuator;
• and
• a sensor system, said sensor system being grounded wherein a portion of said sensor system remains stationary with respect to said grounding surface, and wherein a different portion of said sensor system is coupled to said user object and moves with respect to said grounding surface when said user object moves along said degree of freedom, wherein no substantial play is allowed between said user object and said portion of said grounded sensor system coupled to said user object, said motion of said coupled sensor portion resulting in signals representing a position of said user object along said degree of freedom.

A joystick interface device for use with a host computer updating a graphical simulation in response to user manipulation of said interface device, said host computer commanding said interface device to generate force feedback sensations in coordination with events within said graphical simulation, said interface device comprising:

• a joystick handle grasped by a user;
• a support mechanism which supports said joystick handle while allowing at least two degrees of freedom of motion of said joystick handle with respect to a grounding surface;
• two actuators coupled to said joystick handle, said actuators providing resistance to motion of said joystick handle along each of said two degrees of freedom, wherein a portion of each of said actuators remains stationary with respect to said grounding surface, wherein a coupling between said joystick handle and each of said actuators introduces play between said joystick handle and each of said actuators, and wherein said resistance to motion is varied by said actuators in response to commands from said host computer;
• and
• a grounded sensor system in which a portion of said sensor system remains stationary with respect to said grounding surface and a different portion of said sensor system is coupled to said joystick handle such that no substantial play is allowed between said joystick handle and said different portion of said sensor system, said lack of substantial play allowing said sensor to accurately track the position of said joystick handle along at least one of said degrees of freedom, regardless of said resistance provided by said actuator.

An interface apparatus for interfacing the motion of a user object with a host computer system, said host computer system updating a graphical simulation in response to user manipulation of said interface apparatus, said host computer commanding said interface apparatus to generate force feedback sensations in coordination with events within said graphical simulation, comprising:

• a user object grasped by a user and manipulable by said user in at least one degree of freedom;
• a sensor coupled to said user object such that substantially no play exists between said sensor and said user object, allowing said sensor to accurately track a position of said user object in said at least one of said degree of freedom;
• and
• an actuator coupled to said user object and coupled to said sensor, said actuator outputting a damping resistance on said user object, wherein an amount of play exists between said actuator and said user object and between said actuator and said sensor allowing movement of said user object to be detected by said sensor regardless of an amount of damping resistance output by said actuator.

An interface device for use with a host computer, said host computer commanding said interface device to generate force feedback sensations in coordination with events within a host application, said interface device comprising:

• a user object engaged by a user;
• a support mechanism which supports said user object while allowing at least two degrees of freedoms of motion of said user object with respect to a base;
• two grounded actuators coupled to said user object wherein rotary backlash between said object and each of said actuators introduces play between said object and each of said grounded actuators, said grounded actuators providing resistance to motion of said object along each of said two degree of freedom, wherein a portion of each of said actuators remains stationary with respect to said base, and wherein said resistance to motion is varied by said actuators in response to commands from said host computer;
• and
• a sensor system grounded such that a portion of said sensor system remains stationary with respect to said grounding surface, and wherein a different portion of said sensor system is coupled to said user object such that substantially no play exists between said object and said coupled portion of said sensor system, said lack of play allowing said sensor system to accurately track a position of said user object along at least one of said degrees of freedom regardless of said resistance provided by said actuators.

An interface device for use with a host computer system displaying a graphical object within a graphical environment, said host computer system updating the location of said graphical object in response to user manipulation of said interface device, said host computer system commanding force resistance to said interface device in coordination with interactions between said graphical object and said graphical environment, said interface device comprising:

• a user object grasped by a user and movable in a plurality of degrees of freedom with respect to said fixed surface;
• a tranducer system coupled to said user manipulatable object, said transducer system including an actuator and a sensor, said actuator providing damping resistance to motion of said user manipulatable object, and said sensor detecting movement of said user manipulatable object along a degree of freedom and generating a sensor signal;
• a local microprocessor separate from said computer system and coupled to said transducer system for executing a process in parallel with said host computer system, said microprocessor reporting data to said computer system representative of said sensor signal, said microprocessor receiving a command from said host computer system and causing said transducer system to provide said damping resistance to motion of said object in accordance with said host command, wherein said microprocessor decodes said host command and determines a magnitude of a damping resistance to be applied on said user object that is coordinated with said host computer system updating said graphical environment, wherein said damping resistance produced by said transducer system upon said user object simulates a feel of at least one of a plurality of feel sensations, said feel sensations including moving through a fluid, moving over a textured surface, and colliding with a simulated obstruction.

An interface device for use with a host computer, said host computer commanding said interface device to generate force feedback sensations in coordination with events within a host application, said interface device comprising:

• a user object engaged by a user;
• a support mechanism which supports said user object while allowing two degrees of freedoms of motion of said user object with respect to a base wherein said two degrees of freedom allow said user object to move in a plane;
• two linear actuators coupled to said user object for providing resistance to motion of said object along each of said two degree of freedom, wherein said linear actuators are grounded such that a portion of each of said linear actuators remains stationary with respect to said base, and wherein said resistance to motion is varied by said linear actuators in response to commands from said host computer;
• and
• a grounded sensor system including a portion that remains stationary with respect to said grounding surface, and wherein a different portion of said sensor system is coupled to said user object such that substantially no play is allowed between said object and said different portion of said sensor along one of said degrees of freedom, said substantial lack of play allowing said sensor to accurately track the position of said user object along said degrees of freedom.

An apparatus for interfacing the motion of a user object with a host computer system comprising:

• a sensor for detecting movement of said user object along a degree of freedom, said sensor being operative to develop a sensor signal, wherein a representation of said sensor signal is reported to said host computer system over a communication interface;
• an actuator coupled to said object for imparting resistance to movement of said user object in response to a command from said host computer sent over a communication interface;
• a local microprocessor separate from said host computer and executing routines in parallel with host execution of a graphical simulation, said local microprocessor reading said sensor signal and reporting a representation of said sensor signal to said host computer, said local microprocessor receiving a host command from said host computer and controlling said actuator in response to said host command, said host command specifying the magnitude of a damping resistance to be generated by said actuator for movement of said object along a particular direction of said degree of freedom;
• and
• a local routine executing on said local microprocessor for controlling said actuator to produce a damping resistance of said specified magnitude, said local routine monitoring said sensor signal, determining a direction of motion of said user object along said degree of freedom, and modifying the magnitude of damping resistance to be generated by said actuator in response to said direction.