Computer graphics processing and selective visual display system – Display peripheral interface input device – Cursor mark position control device
Reexamination Certificate
1999-10-06
2002-01-29
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Cursor mark position control device
C345S163000, C345S167000, C345S168000, C345S156000, C463S030000, C463S037000, C463S038000
Reexamination Certificate
active
06342880
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to interface devices for allowing humans to interface with computer systems, and more particularly to computer interface devices that allow the user to provide input to computer systems and provide force feedback to the user.
Computer systems are used extensively in many different industries to implement computer controlled applications and tasks, and are also very popular with the mass market of home consumers. A computer system typically displays a visual environment to a user on a display screen or other visual output device. Users can interact with the displayed environment to perform functions and tasks on the computer, such as playing a game, experiencing a simulation or virtual reality environment, using a computer aided design system, operating a graphical user interface (GUI), performing file manipulation, or otherwise influencing events or images depicted on the screen. Such user interaction can be implemented through the use of a human-computer interface device, such as a joystick, mouse, trackball, stylus, tablet, pressure-sensitive ball, or the like, that is connected to the computer system controlling the displayed environment. Typically, the computer updates the environment in response to the user's manipulation of a user-manipulatable physical object such as a joystick or mouse, and provides feedback to the user utilizing the display screen and, typically, audio speakers. The computer senses the user's manipulation of the object through sensors provided on the interface device.
In some interface devices, tactile and/or haptic feedback is also provided to the user, more generally known as “force feedback.” These types of interface devices can provide physical sensations to the user manipulating a user manipulable object of the interface device. For example, the Force-FX controller from CH Products, Inc. and Immersion Corporation may be connected to a computer and provides forces to a user of the controller. Typically, motors or other actuators are coupled to the user object and are connected to the controlling computer system. The computer system can provide forces on the object in conjunction with application program events by sending control signals to the actuators. The computer system can thus convey physical force sensations to the user in conjunction with other supplied feedback as the user is grasping or contacting the object of the interface device.
In most of the prior art force feedback interface devices, the host computer directly controls forces output by the actuators of the interface device, i.e., a host computer closes a control loop around the system to generate sensations and maintain stability through direct host control.
FIG. 1
illustrates a block diagram of a control system
10
having a typical host controlled loop architecture. A user manipulated object
12
, such as a joystick, of an interface device
13
is moved by a user to interface with a host computer
14
having a host CPU (or microprocessor)
16
, memory
17
, a display device
18
, and I/O circuitry
19
. Sensors
20
detect the position of the user object in provided degrees of freedom and buttons or other controls may also be provided to detect user actions. The sensor data including position data is sent to host computer
14
over a bi-directional communication bus
21
that is typically connected to an interface card
22
plugged into the host computer. To complete the control loop, host computer
14
sends force commands over bus
20
to actuators
24
, and the actuators output forces to the user via user object
12
.
The configuration of
FIG. 1
has disadvantages in the inexpensive mass market, since the functions of reading sensor data and outputting force values to actuators
24
can be a computational burden on the host processor which detracts from the performance of the host in other host tasks and application program execution. In addition, low bandwidth interfaces
22
are often used in mass market computer systems, which reduces the ability of the host computer to control realistic forces requiring high frequency signals.
Some prior art force feedback devices employ a more sophisticated computational architecture having a dedicated microprocessor local to the interface device that communicates with the host computer through a high-level command language. As shown in
FIG. 2
, a local microprocessor
26
reads sensors and control actuators in response to commands from the host computer. The local microprocessor reports data and creates force feedback sensations as a result of parsing host commands. Such an architecture is disclosed, for example, in issued U.S. Pat. No. 5,576,727, and is used in the abovementioned Force-FX joystick from CH Products and Immersion Corp. The advantage of this architecture is that the local microprocessor can reduce the computational burden on the host computer associated with generating force feedback sensations. This is particularly important for “closed loop” force feedback sensations such as simulated springs, dampers, and inertias which are generated as a function of motion of the user manipulatable object as reported by the sensors. These “closed loop” sensations, referred to herein as “condition forces” or “conditions” are computationally intensive because sensors must be read and actuators must be controlled in a very rapid control loop. Such a loop of reading sensors, performing computations on sensor data, and controlling actuators must be performed on the order of 1000 times per second to achieve high fidelity force feedback functionality. Having a local microprocessor perform these closed loop condition forces in response to high level commands from the host computer allows the host application to maintain control over the sensations without being burdened with actually performing the rapid control loops. This enables the use of force feedback with host applications such that the performance of the host application is not significantly degraded when implementing force feedback functionality.
While the above dual-processor architecture is a significant improvement over traditional force feedback architectures, cost constraints on the local microprocessor limit the speed/performance of that processor and thus limit the fidelity of local “closed loop” force sensations. There is a need to develop low-cost methods of reducing the computational burden of the local microprocessor associated with high-fidelity closed loop “conditions” such as springs, dampers, and inertias. This is because low-cost local microprocessors lack the processing speed to perform the force feedback computations of closed-loop conditions while at the same time perform other tasks such as controlling communication with the host computer, decoding commands, reporting sensor data, and creating “open loop” force feedback “effects,” such as jolts, vibrations, etc. The local microprocessor, however, must be kept low-cost and simple to manufacture for mass market force feedback interface devices so that the interface device is competitively priced in the high volume, aggressive home computer and home video game markets.
SUMMARY OF THE INVENTION
The present invention is directed to a new computer architecture for use in a force feedback interface device that further distributes the computational burden associated with force feedback generation by providing a haptic accelerator chip. The accelerator chip performs support functionality so as to relieve the computational burden on the local microprocessor of the interface device and increase performance and fidelity of forces at a low cost.
More specifically, the force feedback interface device is used with a host computer which displays and updates an application program such as a graphical simulation on a display device in response to user manipulation of the interface device. The host computer commands force feedback sensations in response to the user manipulation and in coordination with events within the graphical simulation. The inter
Hasser Christopher J.
Levin Mike D.
Rosenberg Louis B.
Schena Bruce M.
Immersion Corporation
Nguyen Jimmy H.
Riegel James R.
Shalwala Bipin
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