Computer graphics processing and selective visual display system – Display peripheral interface input device – Cursor mark position control device
Reexamination Certificate
2000-02-29
2002-08-06
Saras, Steven (Department: 2675)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Cursor mark position control device
C074S4710XY
Reexamination Certificate
active
06429849
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally concerns an input and control device, and more specifically, a control handle gimbal support mechanism for use in a joystick with haptic feedback, which is employed to produce control signals for controlling machinery, computer games, and the like.
BACKGROUND OF THE INVENTION
Joysticks are typically used to provide input control signals for controlling machinery and computer application programs, such as computer games. A typical joystick includes a control handle that is pivotally rotatable relative to a base in response to input forces applied by a user who is grasping the control handle. Movement of the control handle varies an output signal usually corresponding to the angular displacement of the control handle about orthogonal “X” and “Y” axes. It should be noted that movement of the joystick control handle is sometimes referred to in terms of its motion in the direction of planar X and Y axes, rather than a rotation about these axes. The output signal from a joystick is typically input to a receiving device, such as a computer, which processes the signal for controlling hardware or a computer software program. For example, in a computer executing an aircraft simulator software program, a forward or reverse movement of the joystick control handle about the X axis causes an output signal to be generated that is used to simulate control of the elevators of the aircraft and which thus affects the pitch of the aircraft in the simulation, while lateral movement of the joystick control handle about the Y axis produces a corresponding output signal that is used to control the ailerons of the simulated aircraft, and thus affects roll or rotation of the simulated aircraft about its longitudinal axis.
Joysticks are generally designed to function either as on/off devices or as proportional devices. Lower cost joysticks operating as on/off devices only change the state of a positional switch to provide an indication of whether a minimum displacement of the control handle about one of the axes of the joystick has occurred, whereas proportional devices provide output signals having a magnitude varying proportionally with the extent of the displacement of the joystick control handle away from a known point, generally its “center” point. Higher performance software applications, such as flight simulators, require the use of joysticks that provide proportional output signals.
In addition to providing input signals to a computer or other device relative to displacement of the control handle about the X and Y axes, some joysticks provide an input signal corresponding to a third axis, which is commonly referred to as the “Z” axis. The Z axis generally extends longitudinally through the joystick control handle, and the Z-axis output signal typically is indicative of a rotational angular displacement of the joystick control handle about its longitudinally central axis.
In addition to generating control signals in response to user input, some joysticks are designed to provide force or tactile (“haptic”) feedback to the user. Such devices are often used with computer games, and the haptic feedback feature adds to the user experience. For example, by providing various types of feedback forces that are applied to the control handle, a haptic joystick can convey to the user the physical sensation of an object controlled by the user in a game or simulation colliding with a wall, moving through mud, driving over a bumpy road, etc. This haptic feedback makes the game or simulation more realistic and entertaining.
In general, most haptic joysticks employ various gimbal mechanisms that enable the joystick control handle to be simultaneously pivoted about two coplanar axes (i.e., the X and Y axes discussed above). One type of gimbal mechanism used in joysticks is commonly referred to as a “quarter gimbal” mechanism. A prior art quarter gimbal
10
of this type is shown in
FIG. 1. A
quarter gimbal typically includes a control handle shaft
12
, to which a control handle (not shown) is fixedly or rotatably coupled. The control handle is pivotally coupled to an X-axis gimbal arm
14
by a pivot bearing
15
and is pivotally coupled to a Y-axis gimbal arm
16
by a pivot bearing
17
. The pivot bearings are oriented at an angle of 90 degrees, relative to each other. A cantilevered end
18
of X-axis gimbal arm
14
is pivotally mounted to a base member, e.g., a housing or frame (not shown), by a bearing mount
19
having a centerline
20
that is aligned with the “X” axis, while a cantilevered end
22
of Y-axis gimbal arm
16
is pivotally mounted to the base member by a similar bearing mount
23
having a centerline
24
aligned with the Y axis. When control handle shaft
12
is in its normal “center” position (i.e., in the position shown in the Figure), a centerline
25
of pivot bearing
17
is substantially in coaxial alignment with centerline
20
, while a centerline
26
of pivot bearing
15
is substantially in coaxial alignment with centerline
24
. Furthermore, all of the centerlines are co-planar when the control handle shaft is in this configuration.
In most prior art haptic feedback devices, a separate servo motor for each axis is operatively coupled to the joystick control handle via various mechanisms such that a desired force and/or velocity can be applied to the joystick control handle having a magnitude that is a function of the torque and/or velocity of the motor drive shaft. In a quarter gimbal configuration, each servo motor is typically coupled to a respective gimbal arm through a transmission such as a gear train, so that the force generated at the joystick control handle is increased and the velocity is reduced. Such a configuration is shown in FIG.
1
. As illustrated therein, X-axis gimbal arm
14
is operatively coupled to a servo motor
28
by a gear train
29
that includes a pinion gear
30
, a combination gear drive
32
, and a drive gear
34
. Drive gear
34
is mounted on a drive shaft
36
that is fixedly coupled to X-axis gimbal arm
14
. Similarly, Y-axis gimbal arm
16
is operatively coupled to a servo motor
38
by a gear train
39
that includes a pinion gear
40
, a combination gear drive
42
, and a drive gear
44
mounted on a drive shaft
46
, which is fixedly coupled to Y-axis gimbal arm
16
.
In addition to providing input forces to the joystick control handle, the position of the joystick control handle needs to be determined. This function is generally performed by various electromechanical or optical position sensors that are operatively coupled to the joystick control handle. Examples of such sensors include rotary or linear potentiometers, optical encoders, and linear displacement voltage transducers (LDVTs). In the exemplary quarter gimbal mechanism shown in
FIG. 1
, an X-axis potentiometer
48
is coupled to drive shaft
36
via drive gear
34
, and a Y-axis potentiometer
50
is coupled to drive shaft
46
via drive gear
44
.
Quarter gimbal
10
works in the following manner. It will be initially assumed that the servo motors are not powered and are free to rotate. In response to a user input force upon joystick control handle
12
in a forward direction F along the Y axis and perpendicular to the X axis, control handle shaft
12
pivots about pivot bearing
17
, causing X-axis gimbal arm
14
to pivot about centerline
20
(i.e., about the X axis) in a counterclockwise direction. Since forward direction F is along the Y axis (and thus, aligned with centerline
24
), there is no moment applied about centerline
24
to cause a rotation of Y-axis gimbal arm
16
about the Y axis. As X-axis arm
14
pivots about the X axis, drive shaft
36
is rotated, causing the rotor of servo motor
28
to rotate through the action of gear train
29
. At the same time, the amount of rotation imparted to drive shaft
36
is sensed by X-axis potentiometer
48
. A user input force applied in a reverse direction R would produce a substantially similar result, accept that the rotation imparted to drive shaft
36
woul
An Bin
Stiles William P.
Anderson Ronald M.
Kumar Srilakshmi K.
Microsoft Corporation
Saras Steven
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