U.S. patent application number 11/580452 was filed with the patent office on 2007-02-08 for tactile feedback man-machine interface device.
This patent application is currently assigned to IMMERSION CORPORATION, A delaware Corporation. Invention is credited to Mark R. Tremblay, Mark H. Yim.
Application Number | 20070030246 11/580452 |
Document ID | / |
Family ID | 24257222 |
Filed Date | 2007-02-08 |
United States Patent
Application |
20070030246 |
Kind Code |
A1 |
Tremblay; Mark R. ; et
al. |
February 8, 2007 |
Tactile feedback man-machine interface device
Abstract
A man-machine interface which provides tactile feedback to
various sensing body parts is disclosed. The device employs one or
more vibrotactile units, where each unit comprises a mass and a
mass-moving actuator. As the mass is accelerated by the mass-moving
actuator, the entire vibrotactile unit vibrates. Thus, the
vibrotactile unit transmits a vibratory stimulus to the sensing
body part to which it is affixed. The vibrotactile unit may be used
in conjunction with a spatial placement sensing device which
measures the spatial placement of a measured body part. A computing
device uses the spatial placement of the measured body part to
determine the desired vibratory stimulus to be provided by the
vibrotactile unit. In this manner, the computing device may control
the level of vibratory feedback perceived by the corresponding
sensing body part in response to the motion of the measured body
part. The sensing body part and the measured body part may be
separate or the same body part.
Inventors: |
Tremblay; Mark R.; (Mountain
View, CA) ; Yim; Mark H.; (Palo Alto, CA) |
Correspondence
Address: |
IMMERSION - THELEN REID & PRIEST L.L.P;THELEN REID & PRIEST L.L.P
P.O. BOX 640640
SAN JOSE
CA
95164-0640
US
|
Assignee: |
IMMERSION CORPORATION, A delaware
Corporation
|
Family ID: |
24257222 |
Appl. No.: |
11/580452 |
Filed: |
October 13, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10460157 |
Jun 13, 2003 |
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11580452 |
Oct 13, 2006 |
|
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10186342 |
Jun 27, 2002 |
|
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10460157 |
Jun 13, 2003 |
|
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|
09838052 |
Apr 18, 2001 |
6424333 |
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10186342 |
Jun 27, 2002 |
|
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|
09561782 |
May 1, 2000 |
6275213 |
|
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09838052 |
Apr 18, 2001 |
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09066608 |
Apr 24, 1998 |
6088017 |
|
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09561782 |
May 1, 2000 |
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08565102 |
Nov 30, 1995 |
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09066608 |
Apr 24, 1998 |
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Current U.S.
Class: |
345/156 |
Current CPC
Class: |
G10L 2015/225 20130101;
G06F 3/0484 20130101; G10L 15/22 20130101; G06F 3/011 20130101;
G06F 3/014 20130101; G10H 2220/321 20130101; G06F 3/016 20130101;
G10H 1/34 20130101 |
Class at
Publication: |
345/156 |
International
Class: |
G09G 5/00 20060101
G09G005/00 |
Claims
1. An apparatus for providing a tactile sensation to a sensing body
part in relation to a virtual state signal, said apparatus
comprising at least one vibrotactile unit, wherein each unit
comprises: a mass-moving actuator comprising a shaft and an
eccentric mass mounted on said shaft, said mass-moving actuator
rotating said shaft; fastening means for holding said mass-moving
actuator in relation to said sensing body part for transmitting
vibrations to said sensing body part; and wherein said apparatus
further comprises a signal processor for interpreting said virtual
state signal to produce an activating signal and transmitting said
activating signal to said mass-moving actuator for activating said
mass-moving actuator.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of prior application Ser.
No. 10/460,157, filed Jun. 16, 2003, which is a continuation
application of U.S. application Ser. No. 10/186,342, filed on Jun.
27, 2002, abandoned; which is a continuation of prior U.S.
application Ser. No. 09/838,052, filed on Apr. 18, 2001 now U.S.
Pat. No. 6,424,333; which is a continuation of prior U.S.
application Ser. No. 09/561,782, filed on May 1, 2000 now U.S. Pat.
No. 6,275,213; which is a continuation of prior U.S. patent
application Ser. No. 09/066,608, filed on Apr. 24, 1998 now U.S.
Pat. No. 6,088,017; which is a continuation of U.S. patent
application Ser. No. 08/565,102, filed Nov. 30, 1995, abandoned;
and all of which are incorporated herein by reference.
TECHNICAL FIELD
[0002] This invention relates to a man-machine interface and in
particular to an interface that provides tactile sensation to a
user.
BACKGROUND OF THE INVENTION
[0003] Virtual reality (VR) is an immersive environment which is
created by a computer and with which users have real-time,
multisensorial interactions. Typically, these interactions involve
some or all of the human senses through either visual feedback,
sound, force and tactile feedback (i.e. reflection), smell and even
taste. The key to immersive realism is the capacity of the user to
use his/her hand to interactively manipulate virtual objects.
Unfortunately, the majority of existing commercial virtual reality
systems use hand-sensing devices that provide no haptic feedback.
Nevertheless, some efforts have been made to provide means for
presenting force and tactile information to the user's hand. By
force information, it is meant the application of a set force to a
selected part of the hand, for example, a finger. By tactile
information, it is meant the application of a stimuli, e.g., a
vibration, to a selected part of the hand, e.g., a fingertip pad.
This stimulus, could simulate surface texture or dynamic conditions
at the contact, for example. A few examples of existing force
reflecting devices are the EXOS SAFiRE.TM., the Master II Hand
Master device at Rutgers university, the PERCRO Force-Reflecting
Hand Master and the Sarcos TOPS Force-Reflecting Hand Master. Some
tactile feedback devices that have been developed include the
PERCRO Position-Sensing and Tactile Feedback Hand Master and the
EXOS TouchMaster.TM..
[0004] Virtual reality is not the only field where it is desirable
to feed back force and tactile information to a human
user/operator. Another common area is telerobotics. Some of the
devices mentioned above are also often used as telerobotics
interfaces. Some examples in the literature of feedback devices
designed more specifically for telerobotics include the tactile
shape sensing and display system developed by Kontarinis et al.,
the voice-coil based tactile feedback device used by Patrick et al.
and the pin-based tactile display array developed by Kaczmarek and
Bach-y-rita. Other applications for a vibrotactile unit of the
subject invention include, but are not limited to, gesture
recognition, music generation, entertainment and medical
applications.
[0005] In an ideal case, it would be desirable to provide full
force and tactile feedback to a user to make the virtual reality or
telerobotic experience as realistic as possible. Unfortunately,
most force feedback devices are cumbersome, heavy, expensive and
difficult to put on and remove. Many of the tactile feedback
solutions are also cumbersome, complex and fragile. Additionally,
some of the tactile feedback devices described in the literature,
such as small voice coils mounted to directly contact the skin,
tend to numb the skin after only a few seconds of operation and
then become ineffective as feedback devices.
SUMMARY OF THE INVENTION
[0006] An object of the invention is a man-machine interface which
may be employed in such areas as interactive computer applications,
telerobotics, gesture recognition, music generation, entertainment,
medical applications and the like. Another object of the invention
is a mass which is moved by a "mass-moving actuator" which
generates a vibration that a user can feel. Yet another object of
the invention is the generation of an activating signal to produce
the vibrations either as a result of the user's state or as a
result of environmental conditions, whether virtual or physical.
Still another object of the invention is vibrating the bone
structure of a sensing body part, as well as skin mechanoreceptors,
to provide feedback. Yet still another object of the invention is
the complex actuation of vibratory devices.
[0007] The tactile sensation that a user feels is generated by a
vibrotactile unit mounted on, or in functional relation to, a
sensing body part of a user by a fastening means. In one
embodiment, the vibrotactile device comprises a mass connected
eccentrically to a mass-moving actuator shaft (i.e. the center of
mass of the mass is offset from the axis of rotation). Energizing
the mass-moving actuator causes the shaft to turn, which rotates
the eccentric mass. This rotating mass causes a corresponding
rotating force vector. A rapidly rotating force vector feels to the
user as a vibration. A slowly rotating force vector feels like a
series of individual impulses. For a small number of rapid
rotations, the rotating force vector feels like a single impulse.
We will use the term "vibration" to denote a change in force vector
(i.e., direction or magnitude). Examples of vibrations include, but
are not limited to a single impulse, a sinusoidal force magnitude,
and other functions of the force vector. We use the term "tactile
sensation" to refer to the feeling perceived by a user when their
sensing body part experiences vibrations induced by a vibrotactile
unit.
[0008] A signal processor interprets a state signal and produces an
activating signal to drive the mass-moving actuator. The variable
components of the state signal may be physical (e.g., measured), or
virtual (e.g. simulated, or internally generated); they may vary
with time (e.g., the state variables may represent processes); and
they may be integer-valued (e.g., binary or discrete) or
real-valued (e.g., continuous). The signal processor may or may not
comprise a computer which interprets and further processes the
state signal. The signal processor comprises a signal driver which
produces an activating signal supplying power to, or controlling
the power drawn by, the vibrotactile unit. The power may be, but is
not restricted to, electric, pneumatic, hydraulic, and combustive
types. The driver may be, but is not restricted to, an electric
motor controller comprising a current amp and sensor for closed
loop control, a flow valve controlling the amount of a pressurized
fluid or gas, a flow valve controlling the amount of fuel to a
combustion engine and the like. The details of such a signal
processor and mass-moving actuator are common knowledge to someone
skilled in the art.
[0009] The state signal may be generated in response to a variety
of conditions. In one embodiment, one or more sensors measuring
physical conditions of the user and/or the user's environment may
generate one or more components of a physical state signal. In
another embodiment, a computer simulation may determine the one or
more components of a virtual state signal from a simulated (e.g.,
virtual) state or condition. The virtual state may optionally be
influenced by a physical state. The virtual state includes anything
that a computer or timing system can generate including, but not
restricted to, a fixed time from a previous event; the position,
velocity, acceleration (or other dynamic quantity) of one or more
virtual objects in a simulation; the collision of two virtual
objects in a simulation; the start or finishing of a computer job
or process; the setting of a flag by another process or simulation;
combinations of situations; and the like. The virtual state signal
is a machine-readable measurement of the virtual state
variables.
[0010] The physical state signal is measured from physical state
variables. These variables have relevance to the physical state of
a body part of the user or the user's physical environment. The
physical state variables includes any measurable parameter in the
environment or any measurable parameter relating to a body part of
the user. Some examples of measurable physical parameters in an
environment include but are not restricted to, the state of a body
part, the position of objects in the environment, the amount of
energy imparted to an object in the environment, the existence of
an object or objects in the environment, the chemical state of an
object, the temperature in the environment, and the like. The state
of a body part may include the physical position, velocity, or
acceleration of the body part relative to another body part or
relative to a point in the environment. The state of a body part
may also include any bodily function, where the measured state
signal may include the output from an electroencephalograph (EEG),
electrocardiograph (ECG), electromyograph (EMG), electrooptigraph
(EOG) or eye-gaze sensor, and sensors which measure joint angle,
heart rate, dermal or subdermal temperature, blood pressure, blood
oxygen content (or any measurable blood chemical), digestive
action, stress level, voice activation or voice recognition, and
the like. The user's voice may constitute a measured physical state
variable, where his spoken words are sensed and/or recognized to
generate a corresponding activating signal. The physical state
signal is a machine-readable measurement of the physical state
variables.
[0011] The state signal is presented to the signal processor which
interprets the state, and then determines how and when to activate
the vibrotactile units accordingly. The signal processor produces
an activating signal which may be in response to an event it
interprets from the state signal. Examples of events include
contact, gestures, spoken words, onset of panic or unconsciousness,
and the like. The interpretation of the state signal may or may not
be a binary event, i.e. the simple changing of state between two
values. An example of a binary event is contact vs. non-contact
between two virtual or real objects. The process of interpreting
may include any general function of state variable components. The
interpretation function may produce an output control value which
is integer or real-valued. A non-binary-valued interpretation
output typically relates to the signal processor producing a
non-binary activation signal.
[0012] By varying the functional form of the activation signal, the
type of feedback that the vibrotactile device generates may also be
varied. The device may generate a complex tactile sensation, which
is defined to be a non-binary signal from a single or multiple
vibrotactile units. Examples of complex tactile sensations include
(1) varying the amplitude of vibration with a profile which is
non-uniform over time; (2) varying the frequency of vibration; (3)
varying the duration of impulses; (4) varying the combination of
amplitude and frequency; (5) vibrating two or more vibrotactile
units with a uniform or non-uniform amplitude profile; (6)
sequencing multiple vibrotactile units with different amplitude or
frequency profiles; and the like.
[0013] The frequency and amplitude of the vibration or impulse may
be changed by modifying the activating signal to the mass-moving
actuator. The frequency and amplitude may also be controlled by
increasing the mass or by changing the radius of gyration (e.g.
changing its eccentricity). For example, the mass may be changed by
pumping fluid into an eccentrically rotating container. The sense
of frequency that the user perceives may be changed independently
of the amplitude by modulating the power to the vibrotactile unit
at a variable frequency. This technique is called amplitude
modulation, which is common knowledge to those skilled in the art.
This change in frequency and amplitude may be used to convey
complex, compound or other forms of information to the user.
[0014] Sensors may be mounted on the vibrotactile unit or the
sensing body part to determine the frequency and amplitude of
vibration sensed by the user. A feedback control loop may be added
which uses this information to more tightly control the frequency
and amplitude, or to reach peak efficiency at the resonant
frequency of the collective vibrating device-body system.
[0015] Examples of a sensing body part on which the vibrotactile
unit may be mounted, or in functional relation to the vibrotactile
unit, include, but are not limited to: the distal part of a digit,
the dorsal (back) side of a phalanx or metacarpus, palm, forearm,
humerus, underarm, shoulder, back, chest, nipples, abdomen, head,
nose, chin, groin, genitals, thigh, calf, shin, foot, toes, and the
like. A plurality of vibrotactile units may be disposed on or near
different sensing body parts, and may be activated in unison or
independently.
[0016] Each vibrotactile unit may be affixed to the body by a
fastening means. The fastening means is defined to be the means of
attaching the vibrotactile unit to a sensing body part,
transmitting (and possibly modifying) the vibrations created by the
vibrotactile unit. This means may be one that is flexible such as a
strap made of cloth or soft polymer, or rigid, such as metal or
hard polymer which grabs or pinches the flesh, skin or hair. The
fastening means may also include gluing or taping to the skin or
hair, or tying with a string or rope around a limb, or attaching to
clothes with Velcro.RTM. or similarly functional means. A
vibrotactile unit may also be attached to another structure which
is then attached to the body part with the same means just
mentioned. The vibrations generated by the actuator may be
transmitted to the sensing body part by the structure (rigid or
non-rigid), or through a linkage transmission or a fluid
transmission.
[0017] The eccentric mass need not be mounted directly onto a motor
shaft. A mechanical transmission may rotate the mass on a different
shaft than the motor shaft. The mass-moving actuator rotates this
shaft. Fluids such as air and liquids may also transmit the motion
from a power source to the rotating eccentric mass. Changing
magnetic fields may also be employed to induce vibration of a
ferrous mass.
[0018] As previously mentioned, state signals may relate to a
physical or virtual state. When the state represents a physical
condition, the subject invention includes a state measurement
sensor which produces a state signal. This state measurement sensor
may measure some property of the sensing body part. Recall that the
body part associated with receiving the vibrotactile stimulation is
called the sensing body part, the body part associated with
producing the activating signal is called the measured body part.
The signal processor may receive signals from this sensor such as a
tactile, position, bend, velocity, acceleration or temperature
sensor and generate an activating signal. In this way, the user may
receive feedback based on his actions or physical state. For
example, the vibrotactile device may be used to train the user to
do some physical motion task. In this case, the position or motion
of the body part which is to do the motion task is measured by the
state measurement sensor and is also the sensing body part. Direct
stimulation to the body part being trained enhances the training of
the task. Complex actuation in the form of a function of different
levels of frequency or amplitude may inform the user whether his
actions are correct or incorrect; the level of correctness may
correspond to the level of frequency or amplitude.
[0019] In addition, the sensing body part (which is also the
measured body part) may have a graphical representation shown to
the user. The user may also be presented with visual, auditory,
taste, smell, force and/or temperature cues to his actions in
combination with the vibrotactile cues provided by the subject
invention. The user may be immersed in a virtual environment. The
user may see a graphical representation of his/her body part
interact with virtual objects and simultaneously feel a
corresponding tactile sensation simulating the interaction. For
example a user may have his/her fingers be the sensing and measured
body parts. The user may then see his/her virtual hand in the
virtual environment contact a virtual object. The user would then
feel an increasing vibratory stimulation on his/her physical
fingertip as he increased the virtual pressure on the virtual
object using the virtual fingertip.
[0020] As previously discussed, using the vibrotactile device of
the subject invention, a user may receive tactile sensations based
on the state of his body parts. In the previous case the state
included the position, and other dynamic quantities, of the body
parts. In certain applications, the measured body part is the same
as the sensing body part (the list of possible sensing body parts
mentioned earlier also applies to measured body parts); in other
applications they are different body parts. When the measured body
part is different than the sensing body part, the subject invention
acts as a coupling device which relates the sensing body part and
the measured body part.
[0021] In another application, the user may receive tactile
feedback as a result of the conditions of a computer simulated
environment, not necessarily related to the user's actions or
state. The vibrotactile units with varying actuation levels may be
used to simulate a variety of contact situations, e.g., contact
with fluids and solids, and contacts which are momentary or
continuous. For example, a user immersed in a computer simulated
virtual environment may feel simulated fluid (like air or water)
across his body. In such a simulation, an array of vibrotactile
units may vibrate in sequence to correspond to a pressure wave
hitting the corresponding parts of the body; the amplitude of the
vibration may vary to correspond to different levels of pressure
being simulated. A user may also feel a virtual object that comes
into contact with a portion of his virtual body. The user may feel
a virtual bug crawl up his virtual arm by sequencing an array of
vibrotactile units. To accompany the tactile sensations received by
the user which are uncorrelated with his actions, the user may be
presented with visual, auditory, taste, smell, force, temperature
and other forms of feedback in order to enhance the realism of the
simulated environment.
[0022] In yet another application of the vibrotactile device, a
group of users may receive tactile sensations. In one example,
users may wear individual vibrotactile units, or they may also
share vibrotactile units as follows. A tactile sensation may be
shared by one or more users making physical contact with the
sensing body part of another user. For example, one user may wear
vibrotactile units on the backs of his fingers. A second user, not
wearing any vibrotactile units, may obtain vibrotactile feedback
transmitted via the first user when the first user places the
palmar side of his fingers on a sensing body part of the second
user. The activating signal for each vibrotactile unit may be
computer controlled via either user's actions or through a computer
simulated event. In a second example, a group of users may each
receive identical tactile feedback through individually mounted
vibrotactile units. The common activating signal may correspond to
measured body parts from a single, optionally separate, user.
Different users may also be responsible for producing the common
activating signal for one or more vibrotactile units. For instance,
the movement of one user's arm may control the vibrotactile unit on
each user's arm; and the voice of a second user may control the
vibrotactile unit on each user's back; the eye-gaze of three other
users may control the vibrotactile unit upon which they stare in
unison. An example application of a single user controlling many
user's vibrotactile sensations is a new form of entertainment where
a performer creates vibrotactile sensations for an audience.
[0023] In a preferred embodiment, the vibrotactile units are
affixed to an instrumented glove, such as the CyberGlove.TM.
manufactured by Virtual Technologies of Palo Alto, Calif., USA. The
CyberGlove has sensors in it which measure the angles of the joints
of the hand. The fingertips of the CyberGlove are open so that the
user may reliably handle physical objects while wearing the glove.
The open fingertips allow the user to feel the sensations of real
objects in conjunction with the generated vibrotactile sensations.
The fingertips need not be open, they may be fully enclosed as in
the 22-sensor model of the CyberGlove. The mass-moving actuator of
each vibrotactile unit is encased in a cylindrical housing and
mounted onto the glove on each of the fingers and thumb, and on the
palmar side of the hand. Each mass-moving actuator is composed of a
small DC motor with an eccentric mass mounted rigidly onto the
shaft of the motor. The casing is made of tubular plastic and
serves to protect the motion of the mass from the user and protect
the user from the rotating mass. The casing may be made of any
rigid or semi-rigid material including but not limited to steel,
aluminum, brass, copper, plastic, rubber, wood, composite,
fiberglass, glass, cardboard, and the like. The casing may form a
solid barrier, a wire-mesh, grid or column-like support capable of
transmitting vibrations from the mass-moving actuator to the
fastening means. The instrumented glove informs a computer of the
position of the user's hand and fingers. The computer, which is
part of the signal processor, then interprets this hand state
signal (and any virtual state signal if the application calls for
it). The computer then generates a control signal, which when
processed by the driver, activates the actuators to create tactile
sensations.
[0024] One feature of the embodiment of the subject invention just
described, which employs an eccentric mass, is that the energy
imparted into the system can be less than the energy required when
using electromagnetic coils (such as the speaker voice coils used
by Patrick et al. and the EXOS TouchMaster). Energy is stored as
rotational inertia in the eccentric mass, whereas the
voice-coil-based systems lose all inertial energy each time the
coil change directions.
[0025] Another feature of the subject invention is that vibrating
the bone structure of a body part, as well as skin
mechanoreceptors, has an advantage over stimulating just the skin
mechanoreceptors (such as Meissner, Merkel, Ruffini and Pacinian
corpuscles) in that the nerves do not get easily overstimulated and
do not become numb. In addition, the form of information to the
user is closer to a physical contact sensation where the muscles
and joints are stimulated, as is done by full force feedback
systems. As a result, the vibrotactile units need not be attached
to a body part which has sensitive skin mechanoreceptors. For
example, a vibrotactile unit may be attached to a fingernail or an
elbow.
[0026] In an embodiment in which a user is immersed in a computer
simulated environment, actuation of vibrotactile units can
approximate the sensation of touching physical objects as full
force feedback devices do. The deep impulsive sensation in the
muscles and joints generated by the vibrotactile units simulates
the change in proprioceptive state as the user touches a virtual
object. The subject invention provides numerous advantages over a
sustained force feedback device. For example, because of its
simplicity, the vibrotactile device of the subject invention can be
made smaller, lighter, less encumbering, more robustly and
cheaper.
[0027] The subject invention may be used in combination with a
sustained force feedback device as provided by Kramer in U.S. Pat.
No. 5,184,319, Kramer in U.S. patent application Ser. No.
08/373,531 (allowed), Zarudiansky in U.S. Pat. No. 4,302,138,
Burdea in U.S. Pat. No. 5,354,162, and Jacobus in U.S. Pat. No.
5,389,865. These patents and patent applications are incorporated
herein by reference. Such a combination can give a higher frequency
response than that capable of being generated by the sustained
force feedback device and/or to reduce the cost and/or size of the
full system. The subject invention may also be used in combination
with other tactile feedback devices such as heating or cooling
devices, bladder devices or voice coils.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1a is a perspective view of an electric mass-moving
actuator with an eccentric mass attached to its shaft.
[0029] FIG. 1b is a perspective view of a mass-moving linear
actuator with a mass attached to its shaft.
[0030] FIGS. 2a and 2b are a cross-sectional side view and a
perspective view respectively of an example of a vibrotactile
unit.
[0031] FIG. 3 is a perspective view of the vibrotactile unit shown
in FIG. 2b where the vibrotactile unit is attached to the palmar
side of the fingertip.
[0032] FIG. 4 is another perspective view of a vibrotactile unit
attached to the dorsal side of the fingertip, where it makes
contact with the nail.
[0033] FIG. 5 is a perspective view of a vibrotactile unit attached
to the dorsal side of the proximal phalanx.
[0034] FIG. 6 is a perspective view of a vibrotactile unit attached
to the palm of the hand
[0035] FIG. 7 is a perspective view of a vibrotactile unit attached
to the dorsal side of the metacarpus (the back of the hand).
[0036] FIG. 8 is a perspective view of a vibrotactile unit attached
to the top of the foot.
[0037] FIG. 9 is a side view of a multitude of vibrotactile units
attached to a variety of places on the head.
[0038] FIGS. 10a and 10b are front and back views respectively, of
a multitude of vibrotactile units attached to a variety of places
on the body.
[0039] FIGS. 11a and 11b are perspective and front views
respectively of a fastening means where the palmar side of the
fingertip receives greater stimulation without the vibrotactile
unit getting in the way of manipulation.
[0040] FIGS. 12a and 12b are perspective and front views
respectively of a fastening means where the palmar side of the
fingertip receives greater stimulation without the vibrotactile
unit getting in the way of manipulation.
[0041] FIG. 13 is a perspective view of a fastening means where no
casing is required for the vibrotactile unit because the moving
mass is mounted away from the finger thus reducing the possibility
of interference.
[0042] FIG. 14 is a side view of an another fastening means where
no casing is required for the vibrotactile unit because the moving
mass is mounted away from the finger thus reducing the possibility
of interference.
[0043] FIG. 15 is a perspective view of a fastening means where the
vibrotactile unit is attached to the body via a spring that is used
to alter the amplitude and frequency of the sensed
oscillations.
[0044] FIGS. 16a, 16b and 16c are front schematic views and 16d is
a perspective view of a vibrotactile unit where the radius of the
gyration of the eccentric mass increases as the angular velocity of
the shaft increases. FIGS. 16a, 16b, and 16c illustrate the
principle, where w.sub.2>w.sub.1>0.
[0045] FIG. 17 is a schematic electrical-mechanical signal
propagation diagram.
[0046] FIGS. 18a and 18b show an instrumented glove, in this case
the Virtual Technologies CyberGlove.TM., with both position sensors
and vibrotactile units.
[0047] FIGS. 19a and 19b show schematically two applications using
a sensing glove with vibrotactile units attached to the fingers and
back of the hand. FIG. 19a shows a virtual reality application.
FIG. 19b shows a telerobotic application.
[0048] FIG. 20 illustrates schematically an example of a virtual
environment with separate sensing and measured body parts.
[0049] FIGS. 21a and 21b are perspective drawings showing two
applications of the invention for gesture recognition. In FIG. 21a,
the gesture is static and in FIG. 21b, the gesture is dynamic (the
index finger is moving in a pre-determined fashion).
[0050] FIG. 22 is a schematic drawing showing a musical
application.
[0051] FIG. 23 is a schematic drawing showing an entertainment or
relaxation application.
[0052] FIG. 24 is a schematic drawing showing a medical
application.
[0053] FIGS. 25a, 25b and 25c are a schematic drawings illustrating
an amplitude decoupling method.
[0054] FIG. 26a is a perspective drawing and FIG. 26b is a side
view of a vibrotactile unit with a controllable eccentricity. FIG.
26c is an alternative transmission method that can be used to
control the eccentricity of the mass.
[0055] FIG. 27 is an exemplary diagrammatic view of an application
comprising the vibrotactile device, a virtual simulation and a
physical simulation.
DETAILED DESCRIPTION
[0056] FIG. 1a shows one embodiment of a vibrotactile unit obtained
by attaching an eccentric mass (101) to the shaft (102) of a small
d.c. electric motor (100) which serves as the mass-moving actuator.
Here the mass is pie-shaped, however any other shape which offsets
the center of gravity from the axis of rotation, and thus provides
eccentricity, may be used. This eccentricity causes the force
vector to change directions during rotation and thus induces
vibrations in the unit. The mass may be made of any material like
steel, aluminium, plastic or fluid encased in a container, to name
a few.
[0057] FIG. 1b shows another embodiment of a vibrotactile unit
obtained by attaching a mass (103) to the shaft (104) of a linear
mass-moving actuator (105). Here the mass is disk-shaped, however
any other shape may be used. The linear actuator moves the mass
back and forth and thus induces vibrations in the unit by suddenly
accelerating and decelerating it. The mass may be made of any
material like steel, aluminium, plastic or fluid encased in a
container, to name a few.
[0058] FIG. 2a and FIG. 2b are cross-sectional and perspective
drawings respectively of an example of a casing (200) in which a
mass-moving actuator (202) and a mass (201) are contained. Again,
the eccentric mass (201) is attached to the shaft (204) of the
electric motor. The casing has a hole for the motor leads (203) to
escape. The casing protects the moving mass from being disturbed by
the user. It also protects the user from being hit by the mass. The
casing may be made from any rigid material, or variety of
materials, such as aluminum, steel, plastic, glass, glass fiber
composite etc. It is typically desirable to have a small light
weight mass-moving actuator, mass, casing and fastening means so
that the device may be as unencumbering as possible. From here on,
this embodiment of the invention will serve as the sample
vibrotactile unit used in many of the subsequent figures.
[0059] FIG. 3 illustrates one fastening means for attaching the
vibrotactile unit to a finger. In this example, the vibrotactile
unit (300) is attached directly to the palmar side of the fingertip
using a fastening means (301). The fastening means may be made of
either flexible material, such as cloth, fabric, tape, Velcro.RTM.
or a soft polymer, or it may be made of a rigid material such as a
metal, hard polymer or wood, to name a few. The fastening means
need not encircle the finger entirely, it may grab the finger by
clamping or pinching, or by sticking to it such as with glue or
tape. Also, if the user is wearing a glove, the vibrotactile unit
may also be sewn onto the glove or bonded to it and need not be
affixed directly to the hand. This will also be the case in the
following figures which illustrate various ways to position the
vibrotactile unit on the human body.
[0060] FIG. 4 illustrates another way of mounting the vibrotactile
unit (400) onto the finger using a fastening means (401). In this
case the unit is positioned directly above the fingernail on the
dorsal side of the fingertip (the sensing body part) in order to
provide a distinctive tactile sensation, or vibratory stimulus. The
unit may vibrate the nail, the flesh underneath and the bone with
sufficient amplitude that the sensation is felt throughout the
finger, not just locally at the skin.
[0061] FIG. 5 illustrates another way of mounting the vibrotactile
unit (500) onto the finger using a fastening means (501). In this
case the unit is positioned on the dorsal side of the proximal
phalanx. Since the unit gives sensation throughout the entire
finger, touching virtual objects with the palmar side of the hand
will still give sensations to that side even though it is mounted
on the back. When used in conjunction with manipulating physical
objects with the palmar side, the vibrational sensation on the
palmar side is enhanced. These features are not limited to the
proximal phalanx. Mounting to the dorsal side of any phalanx or
limb will produce the same effect.
[0062] FIG. 6 illustrates another way of mounting the vibrotactile
unit (600) onto the user using a fastening means (601). In this
case the unit is positioned in the palm of the user's hand. If a
glove (instrumented or not) is worn, then the unit may also be
mounted inside or outside of the glove in a pocket-like cavity, and
need not be explicitly affixed to the hand.
[0063] FIG. 7 illustrates another way of mounting the vibrotactile
unit (700) onto the user using a fastening means (701). In this
case the unit is positioned on the dorsal side of the metacarpus,
or the back of the hand. Again, if a glove (instrumented or not) is
worn, then the unit may also be mounted inside or outside of the
glove in a pocket-like cavity, and need not be explicitly affixed
to the hand.
[0064] FIG. 8 illustrates another way of mounting the vibrotactile
unit (800) onto the user using a fastening means (801). In this
case the unit is positioned on the top of the user's foot. If a
sock-like garment (instrumented or not) is worn, then the unit may
also be mounted inside or outside of the garment in a pocket-like
cavity, and need not be explicitly affixed to the foot.
[0065] FIG. 9 illustrates another way of mounting vibrotactile
units (900) onto the user. In this example, the units are
positioned on the user's head. If a hat-like garment (instrumented
or not) is worn, then the units may also be mounted inside or
outside of the suit in pocket-like cavities, and need not be
explicitly affixed to the body. Examples of locations include, but
are not limited to, the temples (900), the forehead (901), the top
of the head (902) and the back of the head (903).
[0066] FIG. 10a illustrates another way of fastening vibrotactile
units (1000-1012) onto the user. In these examples the units are
positioned all over the front and the side of the user's body. If a
body suit (instrumented or not) is worn, then the units may also be
mounted inside or outside of the suit in pocket-like cavities, and
need not be explicitly affixed to the body. By actuating a
combination of actuators, the perception of the localization of the
tactile sensation may be controlled. For example, if the actuators
on the forearm (1007) and on the humerus (1005) actuate with equal
intensity, the user may have the perception that there is a single
source of sensation originating in-between the two. This may apply
to any combination of vibrotactile units located anywhere on the
body. This effect is also apparent when multiple vibrotactile units
are activated in sequence. There is a perception that a single
vibration has "moved" between the activating vibrotactile units.
The vibrotactile units displayed in the figure show examples of a
variety of candidate positions for attaching the units. Some of
these positions include, but are not limited to, the forehead
(1000), the shoulders (1001), the side of the arm (1003), the
humerus (1005), the chest (1002), the nipples (1004), the abdomen
(1006), the forearm (1007), the groin (1008), the hips (1009), the
thighs (1010), the knees (1011) and the shins (1012).
[0067] FIG. 10b illustrates another way of fastening vibrotactile
units (1020-1028) onto the user. In these examples the vibrotactile
units are positioned all over the back of the user's body. If a
body suit (instrumented or not) is worn, then the vibrotactile
units may also be mounted inside or outside the body suit in
pocket-like cavities, and need not be explicitly affixed to the
body. The vibrotactile units displayed in the figure show examples
of a variety of candidate positions for attaching the units to the
body. Some of these positions include, but are not limited to, the
back of the head (1020), the base of the neck (1021), between the
shoulder blades (1022), the back of the humerus (1023), the back of
the forearm (1025), the lower back (1024), the buttocks (1026), the
back of the thighs (1027) and the calves (1028). The vibrotactile
units in FIG. 10b may be combined with those in FIG. 10a as well.
This plurality of vibrotactile units shows one way that complex
tactile sensations may be generated with multiple vibrotactile
units.
[0068] FIGS. 11a and 11b show a vibrotactile unit mounted in such a
way that the fingertip may be stimulated without the unit getting
in the way of manipulation with the fingers. FIG. 11a shows a
perspective view of the invention and FIG. 11b shows a frontal
view. A structure (1102), which may be opened or closed at the end,
surrounds the fingertip. The fastening means is comprised of three
parts: part one affixing the finger to the structure; part two
affixing the vibrotactile unit to the structure; part three is the
structure (1102). Part one of the fastening means (1103), which can
be a flexible or rigid membrane, holds the finger against the
structure on the palmar side of the fingertip. This part can be
adjustable, fixed, flexible or stretchable. In part two, the
vibrotactile unit (1100) is mounted atop the structure, away from
the palmar side of the fingertip, using a means (1101) which can be
a flexible or rigid membrane. In this manner, the vibrations from
the vibrotactile unit may be transmitted through the structure
directly to the palmar side of the finger to provide a greater
stimulation of the nerves local to the palmar side. In another
embodiment, the structure (1102) and the vibrotactile unit casing
(1100) can be made of one part, thus eliminating the need for a
part two of the fastening means (1101).
[0069] FIGS. 12a and 12b show the vibrotactile unit mounted such
that the fingertip can be stimulated without the unit getting in
the way of manipulation with the fingers. FIG. 12a shows a
perspective view of the invention and FIG. 12b shows a side view. A
structure (1202) is attached to the palmar side of the fingertip.
The fastening means is comprised of three parts: part one, affixing
the finger to the structure; part two, affixing the vibrotactile
unit to the structure; part three which is the structure (1202).
Part one (1203) may be a flexible or rigid membrane. This part may
be adjustable, fixed, flexible or stretchable. In part two, the
vibrotactile unit (1200) is mounted atop the structure, away from
the palmar side of the fingertip, using a means (1201) which can be
a flexible or rigid membrane. In another embodiment, the structure
(1202) and the vibrotactile unit casing (1200) can be made of one
part, thus eliminating the need for part two of the fastening means
(1201).
[0070] FIG. 13 shows a vibrotactile unit and fastening means where
no casing is required for the mass-moving actuator/mass assembly. A
small rigid or semi-rigid structure (1302) elevates the
vibrotactile unit above the fingertip in such a way that the finger
cannot interfere with the rotation of the eccentric mass (1301)
about the main axis of the shaft (1304) of the mass-moving motor
(1300). The structure (1302) is attached to the fingertip using a
strap (1303) which can be rigid or flexible and which can be either
an integral or separate part of the structure.
[0071] FIG. 14 shows another vibrotactile unit and fastening means
where no casing is required for the mass-moving actuator/mass
assembly. A small rigid or semi-rigid structure (1404) elevates the
vibrotactile unit above the middle phalanx in such a way that the
finger cannot interfere with the rotation of the eccentric mass
(1402) about the main axis of the shaft (1403) of the mass-moving
actuator (1401). The structure (1404) is attached to the middle
phalanx using a strap (1405) which can be rigid or flexible and
which can be either an integral or separate part of the
structure.
[0072] FIG. 15 shows yet another vibrotactile unit (1500) and
fastening means such that the vibrotactile unit is connected to the
fingertip via a form of spring (1501) in order to alter the
amplitude and frequency of the perceived vibrations. A strap (1502)
which can be a flexible or rigid membrane holds the spring against
the fingertip. The spring changes the natural frequency of the
vibrotactile unit. Alternatively, the vibrotactile unit/spring
apparatus could be attached below the finger instead of above it.
The spring may also be replaced by some form of actuator to again
control the amplitude and frequency and/or to extend the range of
amplitude and frequency. In addition a damper may be introduced in
combination with the spring or actuation system to further control
and/or extend the amplitude and frequency of the perceived
vibrations. An electro-rheological fluid may used in the damper to
control the damping term in the mechanical system.
[0073] FIGS. 16a, 16b, 16c, and 16d illustrate a modification to
the way the eccentric mass is mounted to a shaft. The radius of the
gyration K of the eccentric mass increases as the angular velocity
of the shaft increases. The top three drawings (FIGS. 16a, 16b,
16c) illustrate the principle, where w.sub.2>w.sub.1>0, and
the bottom perspective drawing (FIG. 16d) provides an
implementation. In FIG. 16d, a structure (1601) is attached the
shaft (1602) of the mass-moving actuator (1600). The structure
comprises a spring (1604) and mass (1603) assembly. At one end, the
spring is attached to the inside of the structure and at the other
end it is attached to the mass. The mass is free to move towards
and away from the shaft inside a guide in the structure. The radius
of gyration K is the distance between the center of gravity of the
mass (1603) and the main axis of the mass-moving actuator shaft
(1602). As the angular velocity of the shaft increases, the
centrifugal forces felt by the mass increase, causing it to stretch
the spring further and increase the radius of gyration. This
apparatus minimizes the angular inertia of the device at start-up
and then gradually increases the eccentricity of the mass so that
larger vibrations can be obtained at higher angular velocities.
This relieves the stress on the bearings that hold the shaft and
reduces the larger initial torque required to initiate rotation (as
opposed to the torque required to maintain rotation).
Alternatively, the passive spring may be replaced by an active
device which controls or sets the radius of gyration of the mass.
The active device may comprise a shape memory alloy actuator or any
other mechanism capable of controlling the position of the
mass.
[0074] FIG. 17 shows how the electrical and mechanical signals
propagate through the tactile feedback control system in a
preferred embodiment of the invention. The embodiment shown employs
a d.c. servo motor (1701) as the mass-moving actuator of a
vibrotactile unit. A computer (1707), or other signal processing
means, sends a digital value representing the desired actuation
level control signal to the digital-to-analog convert, D/A (1703).
The analog output of the D/A is then amplified by a variable gain
amplifier (1704) to produce an analog voltage activation signal.
This voltage is placed across the servo motor, driving the motor at
a desired angular velocity. The voltage signal may alternately be
converted to a current activation signal for driving the motor at a
desired torque. Velocity damping of the servo control loop may be
performed by tachometer feedback (not shown). The computer (1707),
digital-to-analog converter (1703), analog-to-digital converter,
A/D (1702), bus (1709) and variable gain amplifier (1704) may be
elements of a signal processor. Digitized values from A/D (1702)
from analog joint angle sensors (1705) provide the position
information of the fingers (measured body parts) to the computer as
a physical state signal. In a virtual environment application, the
physical state signal may cause motion in a corresponding virtual
hand. If one of the digits of the virtual hand is found to be
intersecting a virtual object, the computer calculates the virtual
force to be applied to the virtual digit using knowledge of the
virtual object's shape and compliance. The computer then causes an
activation signal to be sent to the vibrotactile units mounted on
the user's fingers (sensing body part) to convey tactile
information about that virtual force. Strain gage, fiber optic,
potentiometric, or other angle sensors may be used as analog joint
angle sensors (1705). Strain gage angle sensors are disclosed in
the Kramer et al. U.S. Pat. Nos. Nos. 5,047,952 and 5,280,265,
which patents are incorporated herein by reference.
[0075] FIG. 18a and FIG. 18b illustrate a preferred embodiment of
the invention. An instrumented glove (1820) such as the
CyberGlove.TM. manufactured by Virtual Technologies of Palo Alto
Calif., USA, has sensors (1807-1819) on it which measure the angles
of the joints of the hand (the measured body parts). In the
figures, the fingertips of the glove are open so that the user may
handle physical objects while using the glove. This allows the user
to feel the tactile sensations of real objects which may then be
used in conjunction with tactile sensations generated from the
subject invention. The vibrotactile units (1801-1806) are encased
in cylindrical housings and fastened to the glove on each of the
fingers (1801-1804), the thumb (1805) and on the palmar (1806) side
of the hand. The vibrotactile units are composed of a d.c. motor
(item 202 in FIG. 2) with an eccentric mass (item 201 in FIG. 2)
mounted onto its shaft (item 204 in FIG. 2). The casing is made of
tubular plastic and serves to protect the motion of the mass from
the user and protect the user from the rotating mass.
[0076] FIG. 19a shows a user wearing a sensing glove (1900) which
can measure hand formations as well as the spatial placement of the
hand. The sensing glove has vibrotactile units (1901) fastened to
the fingers and to the back of the hand. The user receives visual
feedback through a graphical representation of his hand on the
computer monitor (1908). The computer (1904) receives the state
signal (information about the spatial placement of the user's hand)
through the sensors mounted on the glove via a glove sensor
interface (1902). When the virtual graphical hand (1906) touches
(1907) a virtual object (1905) on the monitor, the computer sends a
control signal to the vibrotactile unit driver (1903) which then
sends the activation signal to the vibrotactile units (1901).
[0077] In a similar setup, FIG. 19b shows the same glove (1900) and
computer interface remotely controlling a robotic arm (1911)
instead of a graphic display. The robot has contact sensors on its
gripper (1912) that detect when the robot touches physical objects
(1913). The user controls the robot arm through the sensors on the
glove which produce position readings of the fingers (measured body
parts) which are sent to the glove interface device (1902) and then
outputted to the computer (1904) which in turn sends the
appropriate commands to the robot. Robot position and contact
information (1910) is then fed back to the computer as the state
signal. The computer interprets this signal and decides what kind
of vibrational feedback should be sent to the vibrotactile unit
(1901) (other vibrotactile units not shown) on the user via the
vibrotactile unit driver (1903). Force or pressure sensors may be
mounted on the gripper instead of contact sensors. The user then
receives vibrational feedback of varying levels depending on the
force or pressure on the object. This allows a teleoperator to
perform tasks more efficiently and safely, especially in handling
delicate objects that would break under certain grip forces. The
user does not necessarily need to control the robot or the objects
of contact in order to use the tactile feedback. The vibrotactile
device may act simply to inform the user of contact with the object
whether or not as a result of the user's actions.
[0078] FIG. 20 illustrates an embodiment in a virtual reality
context where the measured body part (2003) is the foot, however,
the vibrotactile unit (2001) is mounted on the finger which acts as
the sensing body part (2002). The foot has a graphical object
(2004) associated with it in the computer simulation. In this case,
the graphical object looks like a foot as well. Motions of the foot
are sent to the computer (2008) via the body sensor interface
(2006) and are reflected on the computer monitor (2009). When the
computer (2008) determines that the graphical foot (2004) contacts
a virtual object (2010), the computer interprets this state signal
and sends a control signal to the vibrotactile unit driver (2007)
to activate the vibrotactile unit (2001) on the finger. This may be
due to the user moving his foot so that the graphical foot contacts
(2005) the virtual object, or the virtual object moving into the
graphical foot independent of the user's actions. The user then
needs to correlate the contact of the virtual object with the
sensation at the fingertip. While this does not seem as natural as
vibrating the foot as it makes contact, this illustrates the
sensing body part separate from the measured body part. This is
necessary if the measuring body part cannot coincide with the
sensing body part, for example if the measured body part is the
eye-ball or if the measured body part is on another user.
[0079] FIG. 21a and FIG. 21b illustrate a glove (2101) which
contains both position sensors and vibrotactile units (2100). The
Virtual Technologies CyberGlove.TM. is an example of a glove with
appropriate position sensors. The sensors measure the spacial
placement of the hand and fingers. A computer uses gesture
recognition software to determine if a pre-specified hand formation
or motion has been gesticulated. In FIG. 21a, the vibrotactile unit
signals the user that a particular static pose has been detected. A
different vibrotactile sensation can be generated in response to a
recognized moving hand or arm gesture that includes dynamic motions
(FIG. 21b). This may also be useful in training the gesture
recognition software for the gestures to be recognized. In training
the software, a user must repeatedly make the same gesture to
obtain some sort of average position since humans cannot repeat
gestures exactly. With the vibrotactile feedback, the user may be
trained to better repeat his gestures while at the same time
training the recognition software to recognize his gestures. Better
repetition of the gestures reduces the statistical distribution of
the sensor readings for a given hand gesture which in turn may
improve the performance of the recognition system.
[0080] FIG. 22 illustrates vibrotactile units in a musical
application. The units are attached to a body suit or mounted
directly onto the user's clothing. Different regions on the body
(2200-2210), which contain groupings of vibrotactile units (2211),
may correspond to different musical instruments in an orchestra and
serve to enhance the musical experience. For example, music
produced by a cello produces proportional vibrations on the user's
thigh (2204) through the vibrotactile units located in that body
region. Similarly, the drums induce vibrations in the units that
stimulate the chest area (2201) and so on. Sections of the body
containing multiple vibrotactile units corresponding to one
instrument type may have individual vibrotactile units
corresponding to individual instruments. For example, the cello
section of the body is shown to have the first chair cello on the
upper thigh, and the second chair cello on the lower thigh. The
user may either be a passive listener "feeling" the instruments as
well, or he may be an active participant in creating the music,
receiving the vibrotactile sensations as feedback.
[0081] FIG. 23 illustrates an entertainment application. In this
case an array of vibrotactile units simulates water flow or wind.
In this illustration a user is lying on a couch (2300) and is
immersed in a virtual beach scene and sees the beach through a
head-mounted display (2302). The user hears ocean sounds through
head-mounted earphones (2301) and feels warmth from the sun through
heat lamps (2303). The user then feels wind simulated by the
vibrotactile units as they are pulsed in sequence creating "waves"
of sensation. For example, the wind could flow from head to toes by
alternatively pulsing the vibrotactile units starting with the ones
on the head (2304) and ending with the ones on the toes (2305).
Similarly, water is felt as pulsed waves (although perhaps of
larger amplitude), as the user swims through the virtual water. In
this fashion, the user may be relaxed or entertained.
[0082] FIG. 24a and FIG. 24b illustrate a medical application
where, for example, a user has injured a knee. A vibrotactile unit
(2401) is used in conjunction with bend sensors (2400) mounted on
the knee during physical therapy sessions as shown in FIG. 24a. The
vibrotactile unit notifies the user when the knee is exercised
appropriately and alerts the user if the knee is flexed further
than a safe limit prescribed by a doctor and thus improve recovery
as is illustrated in FIG. 24b. Furthermore, the vibrotactile units,
in conjunction with other sensors, may be used in any biofeedback
application.
[0083] FIGS. 25a, 25b and 25c illustrate an approach for decoupling
the amplitude and frequency components of the vibrations generated
by an eccentric mass-based vibrotactile unit. In this embodiment,
the vibrotactile unit comprises a rotary electric motor (2501), a
mass mounted eccentrically (2500), a sensor (2503) mounted on the
shaft (2502) to determine the angular position of the shaft and a
closed-loop control system. Any other control law may be used that
achieves a single rotation of the shaft. One example is shown in
FIG. 25a. The vertical axis of the graph represents a normalized
current, the horizontal axis represents the rotation of the axis in
radians. This corresponds to the following non-linear control law:
I=1, (.delta..gtoreq..theta.>.pi.) I=-1,
(.pi..gtoreq..theta.>2.pi.-.delta.) I=0,
(-.delta.>.theta.>.delta.)
[0084] With the initial conditions set so that the velocity is zero
and rotational position of the mass, .theta., (in radians) is equal
to a small value, .delta., (FIG. 25b) sending current, I, to the
motor in this manner would cause the mass to accelerate for half of
a full rotation, up to .theta.+.delta. (FIG. 25c), and decelerate
for the other half of the rotation coming to a stop between the
-.delta. and +.delta. position in the ideal case. The actual
position of the -.delta. and the +.delta. position may have to vary
depending on the bandwidth of the control loop and the friction and
damping of the system. The magnitude of vibration or impulse is set
by the amplitude of the current, the frequency is set by repeating
the above control at the desired frequency. A simple feedback
control loop (PID for example) could ensure the initial conditions
are correct before each pulse. The details of this are common
knowledge to those skilled in the art.
[0085] FIG. 26a is a perspective drawing and FIG. 26b is a side
view of a vibrotactile unit with controllable eccentricity. A
structure, such as a slip-disk (2602), is mounted on the shaft
(2601) and is free to slide back and forth along the shaft. The
slip-disk is attached to a linkage (2605) which connects it to the
eccentric mass (2604). A positioning device (2603) controls the
position of the slip-disk on the shaft, which in turn affects the
position of the mass (via the linkage) and thus its eccentricity.
FIG. 26c is an alternative transmission method that can be used to
control the eccentricity of the mass. In FIG. 26c, the transmission
comprises element (2606), which may be a flexible membrane or fluid
inside a hollow shaft (2601) that is connected to the eccentric
mass (2604) at one end and the sliding slip-disk (2602) at the
other. Again, controlling the position of the disk along the shaft
using the positioning device (2603) affects the eccentricity of the
mass. Element 2606 may also be a fluid and 2604 a hollow container.
As the fluid is forced through the tube (2601) by the slip-disk
(2602), or by some other pressure generating means, the container
(2604) is filled with the fluid, thus, increasing the effective
radius of gyration of the center of mass of the fluid. By
increasing the radius of gyration, by whichever means, it is
possible to independently control the amplitude and frequency of
vibration of the vibrotactile unit.
[0086] FIG. 27 provides an exemplary block diagram of the
components and functional relationship between the components
comprising the vibrotactile device when used in an application.
Although some components are shown interrelated with a
unidirectional arrow, the arrows may be bidirectional to provide
bidirectional flow of information. Additional arrows may be added
between blocks to provide for communication between components. An
application may include presenting vibrotactile sensation to a body
part of a user, where the vibrotactile sensation is associated with
a virtual environment simulation (virtual simulation) and/or the
physical state of a body (physical simulation), which may be the
user's body, or another person's body. One or more virtual
simulations may co-exist with one or more physical simulations, and
may be combined with further types of simulations to yield a
vibrotactile sensation.
[0087] The exemplary virtual simulation (2722) of FIG. 27 comprises
a computer (2706) with computer monitor (2709). To produce the
virtual simulation, the computer typically generates, processes,
executes or runs a computer simulation (2705) which is typically in
the form of a computer software program. In the exemplary virtual
simulation, the computer produces a graphical display of a virtual
measured body part on the monitor, where the body part is shown to
be a fingertip (2707) on a virtual hand (2708). The virtual
simulation may internally generate an internal state with a variety
of state variables which comprise a virtual state signal (2703) to
provide to a signal processor (2700). Exemplary virtual state
variables include position, velocity, acceleration, mass,
compliance, size, applying force or torque, composition,
temperature, moisture, smell, taste and other dynamical,
structural, physical, electrical metabolical, moodal, cognitive,
biological and chemical properties of various portions internal to,
and on the surface of, a virtual measured body part. States
variables may also denote functions of state variables, such as
contact of various parts of the virtual hand.
[0088] FIG. 27 also provides an exemplary physical simulation
(2723) comprising a state sensor (2718) and a physical measured
body part (2717). In this example, the physical measured body part
is depicted as a fingertip (2717) on a physical hand (2716). The
state sensor measures the physical state (2719) of the physical
measured body part and produces a physical state signal (2720) to
provide to the signal processor (2700). The physical state signal
(2720) is optionally provided to the computer (2706) and/or
computer simulation (2705) of a virtual simulation (2722).
Exemplary physical state variables include position, velocity,
acceleration, mass, compliance, size, applying force or torque,
composition, temperature, moisture, smell, taste and other
dynamical, structural, physical, electrical, metabolical, moodal,
cognitive, biological and chemical properties of various portions
internal to, and on the surface of, a physical measured body part.
States variables may also denote functions of state variables, such
as contact of various parts of the physical hand.
[0089] As shown in FIG. 27, for both the virtual simulation and the
physical simulation, the signal processor (2700) receives a state
signal and produces an activating signal (2704). For the virtual
simulation, the state signal is the virtual state signal (2703);
for the physical simulation, the state signal is the physical state
signal (2720). When the application comprises both a virtual
simulation and a physical simulation, both a virtual state signal
and a physical state signal may be presented to the signal
processor.
[0090] The signal processor may employ a digital or analog computer
(2701) to interpret one or more input state signals (e.g., a
virtual or physical state signal) and produce a control signal
(2721) which becomes the input signal to a driver (2702). Using the
control signal, the driver produces the activating signal (2704).
When the computer is absent from the signal processor, the driver
determines the activating signal from the state signal or signals.
Whether or not the computer is present in the signal processor, the
activating signal is provided in a form for use by the mass-moving
actuator (2710). For example, the driver may comprise a motion
control module, an operational amplifier, a transistor, a fluidic
valve, a pump, a governor, carburetor, and the like. In the case
where the mass-moving actuator is an electric motor, the activating
signal may be a voltage or current with sufficient electrical power
or current drive to cause the motor to turn.
[0091] In FIG. 27, the mass-moving actuator (2710) is shown to be
an electric motor which turns a shaft (2712) and an eccentric mass
(2711). As the mass is rotated, the entire assembly of 2710, 2711
and 2712 vibrates, producing vibrations (2713). Such vibrations are
transmitted to a sensing body part of a user who perceives a
tactile sensation. In the figure, the sensing body part is
exemplified as the fingertip (2715) of a hand (2714).
[0092] An exemplary application which comprises a virtual
simulation and a physical simulation is summarized as follows:
[0093] A fingertip of a physical hand corresponds to both the
sensing body part (2715) and the physical measured body part
(2717). An instrumented glove, optionally comprising a joint angle
sensor and spatial position sensor, produces a physical state
signal (2720) corresponding to the position of the physical
fingertip. The fingertip position is provided via a wire (e.g.,
electrical or optical), computer bus or other electrical or optical
connecting means to a computer (2706) running a computer simulation
(2705) in software. The fingertip position is often provided in the
form of digital values, typically as joint angles and/or values
corresponding to the six possible spatial degrees of freedom. The
fingertip position may also be in the form of an analog
voltage.
[0094] The computer simulation uses the physical state signal
(2720) corresponding to the physical fingertip position (2719) to
simulate the position and motion of a virtual hand (2708) and
fingertip (2707). The computer simulation displays the virtual hand
on a computer monitor (2709), in addition to displaying a second
virtual object whose attributes may correspond to a second physical
measured object, such as a block, ball, car interior, engineering
part, or other object. The computer monitor may be a desk-top
monitor, head-mounted monitor, projection monitor, holographic
monitor, or any other computer generated display means. The second
physical measured object may also be a body part of the user or a
second user.
[0095] When the user moves his hand, producing a movement of the
virtual hand, the computer simulation detects a level of virtual
contact between the virtual fingertip (2707) and the second virtual
object. The computer simulation then produces a virtual state
signal (2703) where one state variable denotes the level (e.g.,
amount of force) of the virtual contact of the virtual fingertip.
The virtual state signal is transmitted to the signal processor
(2721) via a wire (e.g., electrical or optical), computer bus or
other electrical or optical connecting means. The signal processor
may exist in the computer (2706), in which case the virtual state
signal is typically transmitted via the computer bus. When the
signal processor exists in a separate enclosure from the computer,
the virtual state signal is typically transmitted via a wire.
[0096] The signal processor may convert the state variable level of
virtual contact into an activating signal voltage proportional to
the level of virtual contact force using a digital-to-analog
converter followed by an operational amplifier. The voltage is
presented to the mass-moving actuator (2710) typically by a wire
(e.g., electrical or optical) or other electrical or optical
connecting means. The mass-moving actuator may be a variable speed
electric motor which spins eccentric mass (2711) on its shaft
(2712). The electric motor with eccentric mass are housed in a
plastic housing or casing which is affixed to the dorsal portion of
the instrumented glove surrounding the fingertip, which fingertip
corresponds to both the physical measured body part and the sensing
body part. The affixing is typically done with straps, sewing,
gluing and the like. As the eccentric mass rotates, the electric
motor, mass, casing and sensing body part all vibrate, typically at
a common frequency. Ideally, there is little vibrational
attenuation between the mass and the sensing body part such that as
the eccentric mass rotates, the electric motor, mass, casing and
sensing body part all vibrate with the same amplitude.
[0097] In the application just described, the user may perceive a
cause-and-effect relationship between motion of his fingertip and
the level of vibration he feels. Thus, the position, compliance,
mass, shape and other attributes of a virtual object may be
detected by movement of the user's fingertip, or by movement of the
virtual object, inducing various vibrotactile responses. The
vibrotactile device of the subject invention promotes a sensation
of immersion in a virtual environment where the user is able to
interact with virtual objects as if he were interacting with
physical objects in a physical environment.
[0098] Any publication or patent described in the specification is
hereby included by reference as if completely set forth in the
specification.
[0099] While the invention has been described with reference to
specific embodiments, the description is illustrative of the
invention and is not to be construed as limiting the invention.
Thus, various modifications and amplifications may occur to those
skilled in the art without departing from the true spirit and scope
of the invention as defined by the appended claims.
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