U.S. patent application number 10/043374 was filed with the patent office on 2002-05-30 for interface device for sensing position and orientation and outputting force to a user.
This patent application is currently assigned to Immersion Corporation. Invention is credited to Jackson, Bernard G., Rosenberg, Louis B..
Application Number | 20020063685 10/043374 |
Document ID | / |
Family ID | 22236052 |
Filed Date | 2002-05-30 |
United States Patent
Application |
20020063685 |
Kind Code |
A1 |
Rosenberg, Louis B. ; et
al. |
May 30, 2002 |
Interface device for sensing position and orientation and
outputting force to a user
Abstract
An interface device for use with a computer that provides
locative data to a computer for tracking a user manipulatable
physical object and provides feedback to the user through output
forces. The physical object is movable in multiple degrees of
freedom and is tracked by sensors for sensing the location and
orientation of the object. A device processor can be responsive to
the output of the sensors and can provide the host computer with
information derived from the sensors. The host computer can
provides images on a display, where the computer responds to the
provided sensor information and force feedback is correlated with
the displayed images via force feedback commands from the host
computer.
Inventors: |
Rosenberg, Louis B.;
(Pleasanton, CA) ; Jackson, Bernard G.; (Atherton,
CA) |
Correspondence
Address: |
James R. Riegel
IMMERSION CORPORATION
801 Fox Lane
San Jose
CA
95131
US
|
Assignee: |
Immersion Corporation
|
Family ID: |
22236052 |
Appl. No.: |
10/043374 |
Filed: |
January 8, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10043374 |
Jan 8, 2002 |
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09511413 |
Feb 23, 2000 |
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09511413 |
Feb 23, 2000 |
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09248175 |
Feb 9, 1999 |
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09248175 |
Feb 9, 1999 |
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08784198 |
Jan 15, 1997 |
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08784198 |
Jan 15, 1997 |
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08583032 |
Feb 16, 1996 |
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Current U.S.
Class: |
345/156 |
Current CPC
Class: |
G06F 2203/015 20130101;
G06F 3/011 20130101; G01B 21/04 20130101; G05G 9/04737 20130101;
G01B 7/004 20130101; H01H 2003/008 20130101; G06F 3/0346 20130101;
A63F 2300/1037 20130101; G06F 3/03545 20130101; B25J 9/1692
20130101; G06F 3/038 20130101; G06F 3/0383 20130101; G05B 19/4207
20130101; G01B 5/008 20130101; G05G 5/03 20130101; G06F 3/016
20130101 |
Class at
Publication: |
345/156 |
International
Class: |
G09G 005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 12, 1994 |
US |
PCT/US94/07851 |
Claims
What is claimed:
1. A device for use in conjunction with a computer display
apparatus and a fixed surface, comprising: a stylus; means
supportable on a fixed surface and coupled to said stylus for
supporting said stylus while allowing at least a plurality of
degrees of freedom in the motion of said stylus; and means for
producing a stylus locative signal responsive to and corresponding
with the position of the stylus at any point in time during its
normal operation, said stylus locative signal providing information
for use by a computer display apparatus.
2. A device as recited in claim 1 wherein supporting means is a
mechanical linkage.
3. A device as recited in claim 2 wherein said stylus locative
signal means is in communication with said mechanical linkage.
4. A device as recited in claim 1 wherein said stylus locative
signal means is in communication with said stylus.
5. A device as recited in claim 1 further comprising: a remote unit
having switch capable of being in an on state and an off state; and
command means triggered by said switch when said switch is in its
on state for generating a command signal for receipt by a
computer.
6. A device as recited in claim 5 wherein said remote unit is a
foot pedal unit.
7. A device as recited in claim 2 wherein said mechanical linkage
includes three individual components.
8. A device as recited in claim 2 wherein said mechanical linkage
includes at least three joints.
9. A device as recited in claim 1 further comprising means for
providing resistance to the motion of the stylus.
10. A device as recited in claim 1 wherein said stylus has
pencil-like configuration which can be manually manipulated.
11. A device as recited in claim 1 further comprising: feedback
means for generating force by said support means in response to
force signals provided to said device, said force signals
correlated to information displayed on computer display
apparatus.
12. A method for interfacing a user and a computer display
apparatus, comprising the steps of: providing a stylus; coupling to
said stylus a support apparatus supportable on a fixed surface for
supporting said stylus while allowing at least a plurality of
degrees of freedom in the motion of said stylus; and providing
means for producing a stylus locative signal responsive to and
corresponding with the position of the stylus at any point in time
during its normal operation, said stylus locative signal providing
information for use by a computer display apparatus.
13. A method as recited in claim 12 wherein support apparatus is a
mechanical linkage.
14. A method as recited in claim 13 wherein said stylus locative
signal means is in communication with said mechanical linkage.
15. A method as recited in claim 12 wherein said stylus locative
signal means is in communication with said stylus.
16. A method as recited in claim 12 further comprising the steps
of: providing a remote unit having switch capable of being in an on
state and an off state; and providing a command signal generator
triggered by said switch when said switch is in its on state for
generating a command signal for receipt by a computer.
17. A method as recited in claim 16 wherein said remote unit is a
foot pedal unit.
18. A method as recited in claim 13 wherein said mechanical linkage
includes three individual components.
19. A method as recited in claim 13 wherein said mechanical linkage
includes at least three joints.
20. A method as recited in claim 12 further comprising means for
providing resistance to the motion of the stylus.
21. A method as recited in claim 12 wherein said stylus has
pencil-like configuration which can be manually manipulated.
22. A device as recited in claim 11 further comprising the steps
of: providing feedback means for generating force by said support
means in response to force signals provided to said device, said
force signals correlated to information displayed on computer
display apparatus.
23. In a computer system having a main unit and cursor control
functions and command control functions which are triggered
remotely from said main unit, a device for interfacing a user and
computer, comprising: a remote command control unit separate from a
cursor control unit having a switch capable of being in an on state
and an off state; command means triggered by said switch when said
switch is in its on state for generating a command signal
representative of a command from a user to a computer; and
transmission means for transmitting said command signal to said
computer.
24. A device as recited in claim 21 wherein said remote command
control unit is a foot pedal unit.
25. In a computer system having a main unit and cursor control
functions and command control functions which are triggered
remotely from said main unit, a system for interfacing a user and
computer comprising the steps of: providing a remote command
control unit separate from a cursor control unit having a switch
capable of being in an on state and an off state; generating a
command signal representative of a command from a user to a
computer when said switch is in its on state; and transmitting said
command signal to said computer.
26. A system as recited in claim 23 wherein said remote command
control unit is a foot pedal unit.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a computer-human interface
device, and more particularly it relates to a stylus coupled to a
supportable mechanical linkage for providing commands to a
computer.
BACKGROUND OF THE INVENTION
[0002] As the use of Computer Aided Design (CAD) Systems becomes
more widespread, the need for cursor and command control devices
which accurately and easily track three-dimensional position or
motion is also growing. Devices which allow users to control a
cursor with three-dimensional position and/or orientation commands
are available for various applications. Among them are many
hand-held input devices which allow users to interact with a host
processor by controlling the position of a cursor or manipulating
graphic objects on a computer screen. While these devices allow
three-dimensional information to be transmitted to a computer they
do not allow the user to use gestures and motions which are natural
to the user.
[0003] For example, a prior art device of the type which is used
for three-dimensional control involves the use of accelerometers to
transduce the position and orientation of a stylus in space as
described in U.S. Pat. No. 4,839,838. This device makes no
provisions so the stylus can be grasped in a manner which makes use
of finger dexterity nor does it include mechanical support to
reduce fatigue or enhance user control or dexterity.
[0004] Another prior art example is an ultrasonic position-locating
device like the one shown in U.S. Pat. No. 5,142,506. This device
transduces position and orientation by triangulating ultrasonic
signals. As with the prior art previously described, this device
uses a free-floating stylus which includes no provisions for
mechanical support to reduce fatigue or enhance user control or
dexterity. Furthermore, this device is used with a stylus that is
grasped in the palm of the hand. The use of such a stylus precludes
fine positioning with the fingers and greatly reduces the dexterity
of the user to manipulate position and orientation. In addition,
this device is used with digital buttons on the stylus to send to
the computer command signals. A button of this type is commonly
called a "clicker" on a "mouse." Because such buttons are
mechanically coupled to the free-floating stylus, it is difficult
to push the buttons while maintaining the position and orientation
of the stylus. By pushing down on the button, the user will
necessarily move the stylus from its desired position. Accordingly,
these commands are difficult to control under many
circumstances.
SUMMARY OF THE INVENTION
[0005] In the present invention, the user holds a stylus which is
supported by a support apparatus on a fixed surface so that the
user can easily manipulate the stylus in free space to interact
with a computer. The three-dimensional motion of the user is
translated through the stylus and mechanical linkage to a processor
which communicates with the computer, thus allowing commands to be
sent to the computer which track the three-dimensional motion of
the user. Therefore, cursor control in three-dimensions on the
two-dimensional computer screen is possible.
[0006] In one embodiment, the stylus is supportable on a fixed
surface by a set of mechanical linkages which include individual
components joined together by a sufficient number of joints to
allow several degrees of freedom in the motion of the stylus. These
mechanical linkages provide mechanical leverage, friction,
counter-weighing, and/or spring resistance in order to reduce
fatigue of the user and to provide support to enhance the stability
and dexterity of user manipulation of the stylus,
[0007] In the aforementioned embodiment of the present invention,
the joints of the mechanical linkages are coupled to sensors which
provide information about their position. Such information is
transmitted to a microprocessor so that position and orientation of
the stylus can be computed using kinematic equations associated
with or related to the particular linkage system. In another
embodiment, position and orientation of the stylus is sensed
through the use of ultrasonic, magnetic, or optical position and
orientation sensors mounted on the stylus.
[0008] Another aspect of the present invention includes a remote
control unit which is used in place of a command clicker on the
stylus. For example, a foot pedal or hand-held unit for the user's
opposite hand is included to provide command control to the
computer. Accordingly, manual dexterity of stylus manipulation is
not compromised.
DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a perspective view of an embodiment of the present
invention;
[0010] FIGS. 2A and 2B are block diagrams over-viewing two
different electronic hardware configurations of the present
invention;
[0011] FIG. 3 is a flow chart describing the main software loops
for two different electronic hardware configurations shown in FIG.
2;
[0012] FIGS. 4A and 4B are flow charts describing two different
interrupt service routines for serial output to host computer;
[0013] FIG. 5 is a perspective representation of another embodiment
of the present invention;
[0014] FIG. 6 is a perspective view of still another embodiment of
the present invention;
[0015] FIG. 7 is a perspective representation of another
embodiment;
[0016] FIG. 8 is a perspective view of another embodiment;
[0017] FIG. 9 shows an embodiment of the resistance mechanism of
the present invention;
[0018] FIG. 10 shows another embodiment of the resistance
mechanism; and
[0019] FIG. 11 shows yet another embodiment of the resistance
mechanism.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0020] Referring to FIG. 1, a stylus 11 is shown attached to a
support apparatus which is, in turn, supported on a fixed surface.
By electrical and electronic configurations described below, the
stylus 11 is adapted to provide data from which a computer or other
computing means such as a microprocessor can ascertain the position
and orientation of the stylus as it moves in three-dimensional
space. This information is then translated to an image on a
computer display apparatus. The stylus 11 may be used, for example,
by an operator to change the position of a cursor on a computer
controlled display screen by changing the position and/or
orientation of the stylus, the computer being programmed to change
the position of the cursor in proportion to the change in position
and/or orientation of the stylus. In other words, the stylus 11 is
moved through space by the user to designate to the computer how or
where to move the cursor on a computer display apparatus.
[0021] The stylus 11 is a pen-like stick which can be manipulated
between the fingers, allowing for much better control and fine
dexterity as compared to full hand grips or palm-supported styluses
used by some prior art inventions. While the stylus 11 is described
in terms of manual manipulation, other stylus configurations are
envisioned by the present invention. in particular, this invention
includes manipulation by those unable to manually manipulate a pen.
A stylus of the present invention, need not be linear, but may be
curved or angled so that it may be held, for example, by the foot
or the mouth of a person.
[0022] Because the stylus is supported by a support apparatus which
is in turn supported by a fixed surface or other stabilizing
configuration, the user can manipulate the stylus with a minimum of
effort. Also, if the user chooses to discontinue using the stylus,
it is capable of maintaining its position in space, unattended.
While FIG. 1 shows that preferred embodiment of the present
invention, FIGS. 5-8 show alternative embodiments, such which are
also contemplated under the present invention. It is preferable
that the stylus have enough degrees of freedom to enable it to move
through the mechanical linkage to give the user the amount of
flexibility needed to move the cursor as desired. In FIG. 1, six
degrees of freedom are shown and are labeled as Axis' 16. This, of
course, provides maximum flexibility. Fewer degrees of freedom,
such as a plurality of degrees of freedom, may also be sufficient
depending on the application.
[0023] In one embodiment, the stylus is connected to rigid
individual components which are joined together by joints. While
not shown, other types of support apparatus' are included in the
present invention. For example, other configurations include a
semi-flexible rod or any other moveable while supportive
configuration which can support the stylus in the manner described
herein.
[0024] In FIG. 1, a mechanical linkage pursuant to the present
invention is depicted. The stylus 11 is coupled to supportable
mechanical linkages via joint 12 which, in the shown embodiment,
houses sensors 13A and 13B. Linkage 14, is connected, via joint 15
having position sensors 16A and 16B, to linkage 17. Joint 18 in
turn connects linkage 17 with the vertical base protrusion 20 which
emanates from the base 21. The sensors are used to produce a stylus
locative signal which is responsive to and corresponds with the
position of the stylus at any point in time during its normal
operation. The stylus locative signal is used to provide
information for use by a computer display apparatus of a computer.
The term "joint" as used herein is intended to mean the connection
mechanism between individual linkage components. In fact, two
separate moveable members can be joined; such together forming a
joint.
[0025] The base 21, if necessarily, can be immobilized by securing
it onto the fixed surface 23 by way of bolt, screw or other
attachment mechanism 22. Moreover, the present invention implements
mechanical leverage and rubbing friction (not shown) between the
supportable mechanical linkages 14 and 17 and the joints 12, 15 and
18 in order to provide resistance and support so as to allow better
dexterity than can be achieved with free-floating stylus trackers.
This support and leverage aids in reducing the fatigue associated
with manipulating the free-floating stylus 11.
[0026] As mentioned above, attached to each joint 12, 15 and 18 are
sensors 13A, 13B, 16A, 16B, 19A, and 19B, respectively. These
sensors sense the angle differential before and after motion of the
two segments connected by that joint. The sensors can be, for
example, optical incremental encoders, optical absolute encoders
and potentiometers. Because the three-dimensional position and/or
orientation tracking is achieved mechanically, this preferred
embodiment avoids problems that magnetic and ultrasonic sensors,
such as those shown in the prior art, encounter with metal and
shadowing. However, as shown in FIG. 1, if desired, sensing means
can be used to track the position and/or orientation of the stylus
by mounting a single or several orientation sensors in the stylus
11 itself, such referred to as a stylus mounted sensor 11. An
ultrasound, magnetic, optical or position and orientation sensor
can be used as the stylus mounted sensor 11.
[0027] FIG. 1 also shows a clicker button 24 on stylus 11. The
button is connected to a switch which when in the on state, sends a
signal to the computer giving it a command. In order to provide for
accuracy when sending commands, this invention also includes a
remote clicker unit. Therefore, since the clicking motion occurs at
a distant location from the cursor control, there is little or no
opportunity to accidently move the cursor while making a command.
FIG. 1 shows two configurations for implementing this aspect of the
present invention. The first is identified as an alternate
hand-clicker 25, the second as foot pedal 26.
[0028] Digital buttons 27 and 28 which are connected to switches
(not shown) on the remote attached peripherals such as a hand-held
clicker unit 25 or a foot pedal 26, respectively, can generate
additional digital input such transmitted through lines 25' and 26'
respectively. Either of the shown ancillary remote command units,
such including the hand unit 25 and the foot pedal 26
configurations, are favorable methods of inputting digital commands
by command hardware or software (not shown) because pressing the
button 27 or 28 does not compromise a user's ability to hold the
stylus steady whereas pressing any button 24 on the stylus does
compromise stylus stability.
[0029] Referring to FIG. 2A, the sensors 13A, 13B, 16A, 16B, 19A
and 19B, along with any peripherals 24, 25 or 26, can send their
digital signals directly to a versatile floating-point processor or
microprocessor 32A which is controlled by software stored in a
digital ROM (Read-Only Memory) via transmission line 32' or another
form of transmission, i.e., radio signals. As shown in FIG. 2B, an
alternative embodiment can be used to lessen the demands on the
floating-point processor or microprocessor 32B. The digital inputs
of the sensors 13A, 13B, 16A, 16B, 19A and 19B can be sent
indirectly to the floating-point processor or microprocessor 32B by
way of dedicated chips 13C, 13D, 16C, 16D, 19C and 19D, which
pre-process the angle sensors' signals before sending them via bus
31 to the floating-point processor or microprocessor 32B which
would combine these signals with those from the peripherals 24, 25
or 26. An 8-bit data bus plus chip-enable lines allow any of the
angle determining chips to communicate with the microprocessor.
Moreover, reporting the status of peripherals 24, 25 or 26 includes
reading the appropriate digital switch and placing its status in
the output sequence array. Some examples of specific electronic
hardware usable for sensor pre-processing include quadrature
counters, which are common dedicated chips that continually read
the output of an optical incremental encoder and determine an angle
from it, Gray decoders, filters, and ROM look-up tables.
[0030] The single-chip configuration of FIG. 2A is most applicable
where the angle sensors 13A, 13B, 16A, 16B, 19A and 19B are
absolute sensors, which have output signals directly indicating the
angles without any further processing, thereby requiring less
computation for the microprocessor 32A and thus little if any
pre-processing. The multi-chip configuration of FIG. 2B is most
applicable if the sensors 13A, 13B, 16A, 16B, 19A and 19B are
relative sensors, which indicate only the change in an angle and
which require further processing for complete determination of the
angle.
[0031] In either configuration, if the microprocessor 32A or 32B is
fast enough, it will compute stylus 11 position and/or orientation
(or motion, if desired) on board the embodiment and send this final
data through any standard communications interface such as an
RS-232 serial interface 33 on to the host computer system 34 and to
computer display apparatus 34" through transmission line 34' or
another form of transmission. If the microprocessor 32A or 32B is
not fast enough, then the angles will be sent to the host computer
34 which will perform these calculations on its own.
[0032] In addition to the single-chip and multi-chip
configurations, a variation may consist of a single microprocessor
which reads the peripherals, obtains the angles, possibly computes
coordinates and orientation of the stylus 11, and supervises
communication with the host computer 34. Another variation may
consist of dedicated sub-circuits and specialized or off-the-shelf
chips which reads the peripherals, monitors the angle sensors 13A,
13B, 16A, 16B, 19A and 19B, determine the joint angles, and handle
communications with the host computer 34, all without software or a
microprocessor 32A or 32B.
[0033] Software is only included in the two microprocessor-based
configurations shown in FIGS. 2A and 2B. The more dedicated
hardware a given configuration includes, the less software it
requires. The software consists of a main loop (FIG. 3) and an
output interrupt (FIGS. 4A and 4B).
[0034] Referring to FIG. 3, the main command loop responds to the
host computer 34 and runs repeatedly in an endless cycle. With each
cycle, incoming commands from the host computer are monitored 36
and decoded 37, and the corresponding command subroutines for
reporting angles, thus stylus position and/or orientation (see
FIGS. 4A and 4B), are then executed 38. Two possible subroutines
are shown in FIGS. 4A and 4B. When a subroutine terminates, the
main command loop resumes 39. Available command will include but
are not limited to: reporting the value of any single angle,
reporting the angles of all six angles at one time, reporting the
values of all six angles repeatedly until a command is given to
cease aforementioned repeated reporting, reporting the status of
peripheral buttons, and setting communications parameters. If the
angle sensors require preprocessing, these commands will also
include resetting the angle value of any single angle or otherwise
modifying preprocessing parameters in other applicable ways.
Resetting pre-processed angle values or preprocessing parameters
does not require output data from the device. The microprocessor
32A or 32B simply sends appropriate control signals to the
preprocessing hardware 13C, 13D, 16C, 16D, 19C, and 19D. If the
microprocessor or floating-point processor is fast enough to
computer stylus coordinates and orientation, these commands will
also include reporting the stylus coordinates once reporting the
stylus coordinates repeatedly until a command is given to cease,
ceasing aforementioned repeated reporting, reporting the stylus
coordinates and orientation once, reporting the stylus coordinates
and orientation repeatedly until a command is given to cease,
ceasing aforementioned repeated reporting. If force reflection is
supported, these commands will also include reporting the forces
felt by any single joint, setting the resistance of any single
joint, and locking or unlocking a joint.
[0035] Any report by the subroutines of FIGS. 4A and 4B of a single
angle value requires determining 41 the given joint angle. For the
single-chip configuration shown in FIG. 2A, this subroutine
directly reads the appropriate angle sensor 42 from among sensors
13A, 13B, 16A, 16B, 19A, and 19B. For the multi-chip configuration
shown in FIG. 2B, this subroutine reads the outputs 43 of
pre-processing hardware 13C, 13D, 16C, 16D, 19C, and 19D which have
already determined the joint angles from the outputs of the sensors
13A, 13B, 16A, 16B, 19A, and 19B. Any report of multiple angles is
accomplished by repeatedly executing the subroutine for reporting a
single angle. The subroutine is executed once per angle, and the
values of all angles are then included in the output sequence
array. If the optional parts of the subroutines 45 are included,
then these subroutines become the coordinate reporting subroutines.
Many other commend subroutines exist and are simpler yet in their
high-level structure.
[0036] After determining the given joint angle, the microprocessor
32A or 32B creates an output sequence 44A or 44B by assembling an
array in a designated area of processor memory which will be output
by the microprocessor's communications system at a given regular
communications rate. The sequence will contain enough information
for the host computer 34 to deduce which command is being responded
to, as well as the actual angle value that was requested. Returning
to FIG. 3, a query 36 in the main command loop asks whether the
previous command requested repeated reports. If so, the main
command loop is initiated accordingly. The communications output
process (not shown) may be as simple as storing the output data in
a designated output buffer, or it may involve a standard set of
communications interrupts that are an additional part of the
software. Setting communications parameters does not require output
data from the device. The microprocessor 32A or 32B simply resets
some of its own internal registers or sends control signals to its
communications sub-unit.
[0037] To report the stylus' 11 coordinates, three of the five or
six angle values pre-read and knowledge of link lengths and device
kinematics are incorporated to compute stylus 11 coordinates. These
coordinates are then assembled in the output sequence array.
[0038] To report the stylus' 11 orientation, at least five angle
values are read and knowledge of link lengths and device kinematics
are incorporated to computer stylus 11 orientation. The orientation
consists of three angles (not necessarily identical to any joint
angles) which are included in the output sequence array.
[0039] Forces felt by a joint, setting a joint's resistance, and
locking or unlocking a joint are reported by using interaction of
the microprocessor 32A or 32B with forced-reflecting hardware (not
shown). Reporting forces felt by a joint uses a force sensor
mounted on the joint and then places the resulting value in the
output sequence array. To set a joint's resistance and locking or
unlocking a joint control signals reading from a force sensor to
force-reflection hardware but do not require any output data of the
device.
[0040] Also contemplated in the present invention is computer
software and hardware which will provide feedback information from
the computer to the stylus (not shown). This type of implementation
is known in robotics and thus is easily incorporated into a system
including the present invention. When a surface is generated on the
computer screen, the computer will send feedback signals to the
mechanical linkage which has force generators for generating force
in response to the cursor position on the surface depicted on the
computer screen. Force is applied for example, by added tension in
the joints which is in proportion to the force being applied by the
user and in conjunction with the image on the screen.
[0041] The various configurations of the mechanical linkages shown
in FIG. 5, FIG. 6, FIG. 7 and FIG. 8 which have different numbers
of individual components and joints than shown in FIG. 1 are
illustrative of the numerous possible configurations which can
provide varying degrees of freedom inherent in the present
invention. Referring to FIG. 5, FIG. 6 and FIG. 8, note that a
rounded object such as a ball can act as a joint having motion in
three degrees of freedom. In conjunction with other mechanical
linkages and attachments, this permits sufficient degrees of
freedom for the purposes of the present invention. In each figure,
the orientation of the degrees of freedom of each joint is depicted
by curved lines, numbered consecutively.
[0042] Briefly, FIG. 5 shows a rounded joint 46 at the base such
that three degrees of motion are available at that joint. FIG. 6
shows a three-dimensionally rotatable rounded joint 47 at the base
through which one mechanical linkage can slide linearly and where
the base is attached to a fixed surface 48 such that the surface
does not prohibitively impede the movement of the device. FIG. 7
shows an embodiment where the basal connection can slide about the
base in a two-dimensional plane in the cross configuration 49 on
base 51. FIG. 8 shows a three-dimensionally rotatable rounded joint
52 at a perpendicular projection from the base 53 through which one
mechanical linkage 54 can slide linearly through the joint 52.
[0043] While any of the above discussed configurations or others
can be used in accordance with the present invention, FIGS. 9-11
show different mechanisms for providing resistance to the manual
manipulation of the stylus by the user. FIG. 9, for example, shows
return or tension springs 56 on each joint of the embodiment shown
in FIG. 1. In an alternative embodiment, FIG. 10, shows
counter-weights 57 on each joint. Moreover, FIG. 11, shows a
combination of a return or tension spring 56, a counter-wight 57
and a compression spring 58. The arrangement of the resistance
mechanism used should depend upon the configuration stylus
mechanical linkage combination, such arrangement preferably chosen
to maximize the ease with which the user can manipulate the stylus
11 in free space in accordance with the present invention.
* * * * *