U.S. patent application number 15/464083 was filed with the patent office on 2017-08-10 for method and apparatus for analysis of gait and to provide haptic and visual corrective feedback.
This patent application is currently assigned to IPComm LLC. The applicant listed for this patent is Stanislaw Czaja. Invention is credited to Stanislaw Czaja.
Application Number | 20170225033 15/464083 |
Document ID | / |
Family ID | 59496055 |
Filed Date | 2017-08-10 |
United States Patent
Application |
20170225033 |
Kind Code |
A1 |
Czaja; Stanislaw |
August 10, 2017 |
Method and Apparatus for Analysis of Gait and to Provide Haptic and
Visual Corrective Feedback
Abstract
A system for analysis of user gait and to provide correction in
form of haptic and visual feedback. This system comprises a motion
and force sensors and a haptic actuator embedded in the user shoe
insoles in communication with a smart-phone based analysis
application, configured to calculate motion and orientation of the
user feet in relation to the value, location and distribution of
ground reaction forces measured by sensors located in the shoe
insoles and after analysis of said forces and motion, to provide
haptic feedback to the user foot instructing about the location
(and timing) of pressure the user must apply to achieve an optimal
gait.
Inventors: |
Czaja; Stanislaw; (Cardiff,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Czaja; Stanislaw |
Cardiff |
CA |
US |
|
|
Assignee: |
IPComm LLC
Cardiff
CA
|
Family ID: |
59496055 |
Appl. No.: |
15/464083 |
Filed: |
March 20, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14747179 |
Jun 23, 2015 |
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15464083 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A63B 2220/36 20130101;
H04M 1/7253 20130101; A43B 5/0405 20130101; A61B 5/7225 20130101;
A63C 2203/22 20130101; A61B 2562/0247 20130101; A61B 2505/09
20130101; A63C 3/00 20130101; A43B 5/04 20130101; A63B 2225/20
20130101; A63B 2225/54 20130101; G09B 5/02 20130101; A63B 2220/16
20130101; A63B 24/0006 20130101; A43B 3/0005 20130101; A63B 2220/44
20130101; A63B 2220/74 20130101; A43B 5/1616 20130101; A63B
2071/0636 20130101; A63C 11/003 20130101; A43B 17/00 20130101; A63B
2225/50 20130101; A43B 5/16 20130101; A63C 2203/24 20130101; G01S
19/19 20130101; A63B 2225/02 20130101; A61B 5/0024 20130101; G16H
40/67 20180101; A43B 5/00 20130101; A63B 2071/0655 20130101; G16H
40/63 20180101; A63B 2220/40 20130101; G06F 3/011 20130101; A63B
2244/19 20130101; G06K 9/00348 20130101; A63B 2220/12 20130101;
A63B 71/0622 20130101; A63B 2220/62 20130101; G09B 19/0038
20130101; G16H 20/30 20180101; A61B 2562/0219 20130101; G06F 3/016
20130101; A63B 2220/803 20130101; A63C 2203/12 20130101; A61B
5/1124 20130101; A63B 69/18 20130101; A61B 5/6807 20130101; A63C
2203/18 20130101; A61B 2503/10 20130101; A63B 2220/836 20130101;
A63B 2220/56 20130101; A63B 2220/89 20130101 |
International
Class: |
A63B 24/00 20060101
A63B024/00; A43B 3/00 20060101 A43B003/00; A43B 5/00 20060101
A43B005/00; G09B 19/00 20060101 G09B019/00; A43B 5/04 20060101
A43B005/04; A63B 69/18 20060101 A63B069/18; G09B 5/02 20060101
G09B005/02; A43B 17/00 20060101 A43B017/00; A63B 71/06 20060101
A63B071/06 |
Claims
1. A system to analyze and correct gait and balance of a selected
user by estimating vertical ground reaction force vector applied to
the selected user feet and limbs and to provide haptic corrective
feedback comprising: a motion processing element; a force
processing element; and a haptic processing element and wherein
said motion, force and haptic processing elements are embedded in
the selected user shoe insoles, and are in communication with gait
analysis application based in the selected user smart-phone using
wireless radio interface, and wherein the motion processing element
is configured to estimate timing and phase of gait cycle by
analyzing feet motion and to send said estimate as a first
information to the gait analysis application, and wherein the force
processing element comprising one or more force sensors is
configured to estimate value, and location of ground reaction force
transferred to the insoles and send said estimate as a second
information to the gait analysis application, and wherein based on
the first information and the second information the gait analysis
application estimates location of the Center of Pressure (COP)
applied to the selected user feet, then combining said estimates
with the third information containing the selected user physical
characteristics, and the forth information containing the selected
user calibration parameters, estimates location and movement of the
selected user Center of Mass (COM), and wherein after obtaining
said estimation in conjunction with the estimation of selected user
velocity obtained from the Global Position System (GPS) provides
analysis of the selected user gait and the haptic corrective
feedback.
2. The system of claim 1, wherein motion processing elements
comprises of: a three-axis accelerometer; a three-axis gyroscope; a
three-axis magnetometer; and wherein the force processing element
comprises of: a multiplicity of force pressure sensors; and wherein
the haptic corrective feedback element comprises a haptic actuator,
and wherein said motion, force elements are configured to measure
motion of a selected user feet in a three-dimensional (3-D) space
and in relation to reaction force vector transferred from a ground
to a selected user feet and limbs, and to communicate said motion
and forces to gait analysis application, and wherein the haptic
corrective feedback processing element is configured to receive a
control signals from the gait analysis application, convert said
control signals to vibration and to provide said vibration as a
stimulus to user feet.
3. The system of claim 1, wherein third information stored in gait
analysis application contains physical characteristics comprises
selected user: weight and height; distance between tip of grater
trochanter (hip) and the center of rotation of knee; and the
distance between the center of rotation of knee and the ankle.
4. The system of claim 1, wherein forth information stored in gait
analysis application is obtained during static calibration
procedures and comprises values of natural orientation of selected
user position in 3-dimensional space and location, and distribution
of vertical ground reaction force vectors.
5. The system of claim 1, wherein gait analysis application is
configured to retrieve motion and force data from selected user
shoe insoles and combine said motion and force data with third
information containing selected user physical characteristics;
process said data to estimate current phase of gait, location of
COP and COM, and based on said current measurements and the
filtered history of past gait phases, estimate movement of COP and
COM for the subsequent gait cycle, then communicate correct timing
and location of the pressure point required to achieve optimal
balance for the next gait cycle by applying control signal to a
haptic actuator embedded in the selected user shoe insoles.
6. The system of claim 4, wherein calibration procedures comprises:
obtaining three-dimensional orientation of insoles placed in shoes
of a selected user while the shoes, without the selected user are
placed in a reference position; obtaining recording of the insoles
force sensors values without the selected user; obtaining recording
of three-dimensional orientation of insoles and the insoles force
sensors values while the user stands in the shoes in a natural
standing position; and subtracting the insoles three-dimensional
value obtained when insoles and shoes are placed in a reference
position without the user from the values obtained while the
selected stands in the shoes in a natural standing position and
store said values as the user calibrated natural position; and
subtract the insoles force sensors values obtained when insoles and
shoes are placed in a reference position without the user from the
values obtained while the selected stands in the shoes in a natural
standing position and store said values as the user calibrated
force values.
7. The system of claim 5, wherein COP is obtained by performing
weighted average of all pressure points over the surface of a foot
then weighting said averages over both feet.
8. The system of claim 5, wherein the COM is obtained by performing
weighted average of each body segment of selected user in a
3-dimensional space obtained from motion processing element and the
third information stored in gait analysis application.
9. The system of claim 1, wherein three-dimensional motion and
ground reaction force recorded during motion of a selected user and
the GPS coordinates are processed locally by the selected user gait
analysis application to provide visual and numerical representation
of each phase of gait.
10. The system of claim 1, wherein three-dimensional motion and
ground reaction force recorded during the motion of a selected user
and the GPS coordinates are transmitted to a remote server for
storage or analysis by external recipients or to provide visual and
numerical representation of gait.
11. A method providing haptic and visual feedback intended to
improve selected user balance during all phases of gait by
analyzing the selected user motion in a three-dimensional space in
relation to location, distribution and value of ground reaction
forces transmitted to the selected user feet comprising: obtaining
global and local coordinate system; obtaining natural gait stance
parameters; obtaining a three-dimensional vectors of feet motion;
obtaining distribution, location and value of ground reaction
force; processing the distribution and location of ground reaction
force in relation to motion vectors; subtracting the natural gait
stance parameters from the results 3-dimensional motion vectors and
from the location and distribution of ground reaction force
obtained during each phase of gait and use said difference to
calculate the proper location of Center of Pressure (COP) for the
next gait phase and communicate said location to the selected user
feet; obtaining location GPS coordinates; processing
three-dimensional motion vectors to obtain gait timing and phase;
processing of ground reaction forces in relation to gait timing and
phase to obtain rotational moment applied to joints; transmit
result of gait analysis and the location GPS coordinates to a
remote server using smart-phone cellular radio interface; providing
visual and numerical results of gait characteristics, and wherein
the global and local system coordinates, and three dimensional
motion vectors are obtained by analyzing data from: a three-axis
magnetometer sensor; a 3-axis accelerometer sensor; and a 3-axis
gyroscope sensor, a 3-axis magnetometer sensor, and wherein the
value, location and distribution of forces ground reaction force is
obtained from multiplicity of force sensors embedded in the
insoles, and wherein the timing is derived from the gait analyzer
sampling interval, and wherein the instructions of location and
distribution COP intended to modify gait phases or balance.
12. The method of claim 11, wherein numerical and visual results of
gait and value, location and distribution of ground reaction force
transmitted to the feet and joints comprises: an identification of
the gait cycle phase; a motion and rotational vectors applied to
joints; an effective gait rate; an actual location of the COP; a
desired location of the COP; an actual location of the COM; a
desired location of the COM; and a difference in symmetry between
left and right foot,
13. The method of claim 11, wherein instructions of correct
location and distribution of COP intended to modify gait or balance
is obtained by analyzing gait phase, it's timing in relation to
velocity and ground reaction forces and selected user physical
parameters.
14. The method of claim 13, wherein instructions related to change
in location of force intended to modify gait is provided in form of
haptic vibrations to a toes of selected user feet.
15. The method of claim 14, wherein instructions are provided in a
form of varying frequencies and/or vibration amplitudes.
16. The method of claim 12, wherein calibration procedure
comprises: obtaining global and local coordinates from motion
processing element; obtaining selected user weight; obtaining
orientation of feet in natural stand position; obtaining location
of COP in natural standing position; obtaining location of COM in
natural standing position; and performing measurements of
distribution and location of force applied by feet of a selected
user to skiboot insoles in standing position when the selected user
is not in motion and the selected user rests in a natural position
with body mass equally distributed between both feet; leans on an
inner edges of skis as in left and right turn; and performing
measurements of the distribution and the location of force applied
to the skiboot insoles during a test run and storing results as a
reference parameters.
17. A non-transitory computer accessible memory medium for storing
program instructions pertaining to a system providing haptic and
visual feedback of motion and forces transmitted by feet of a
selected user to a skiboot insoles, wherein the program
instructions execute all of the following: maintaining
communication with a motion and force processing elements embedded
in the skiboot insoles and with a remote server; obtaining system's
global and local coordinates by analyzing data obtained from an
accelerometer and magnetometer sensors; obtaining 3D motion of feet
of the selected user by analyzing data obtained from an
accelerometer sensor, gyroscope sensor, magnetometer sensor and an
atmospheric pressure sensor; obtaining distribution and location of
force applied by feet of the selected user to the skiboot insoles
and processing said distribution and location of forces in relation
to a 3D motion vectors of the skiboot insoles to derive timing of
change in distribution and location of force required to perform
successful turn; providing instructions about timing of change in
distribution and location of force required for successful
termination of turn by applying control signals to a haptic
actuators embedded in the skiboot insoles; obtaining location GPS
coordinates; transmitting motion, forces and location GPS
coordinate data to remote server using smart-phone cellular radio
interface; receiving instruction required for successful
termination of turn from a remote terminal and applying said
instructions as control signals to the haptic actuators embedded in
the skiboot insoles; performing calibration procedure to obtain
reference values of force during static and dynamic test
conditions; and providing visual and numerical results of motion
and timing of change in the distribution and location of force
applied by feet of the selected user to the skiboot insoles.
18. The non-transitory computer accessible memory medium of claim
19, wherein results obtained during calibration, dynamic test or a
regular runs are collected independently for a left turn and a
right turn and sorted into a velocity and a radius bins, then said
velocity and radius bins are compared and difference is displayed
as difference in symmetry of force distribution.
Description
[0001] This application is a Continuation in Part application of
non-provisional application Ser. No. 14/747,179 titled "Method and
Apparatus to Provide Haptic and Visual Feedback of Skier Foot
Motion and Forces Transmitted to the Ski Boots" filled on Jun. 23,
2015, hereby incorporated by reference in its entirety as though
fully and completely set forth herein.
FIELD OF THE INVENTION
[0002] The present invention relates to the field of visualization
of motion, weight distribution and forces transferred by the feet
to the insole of the user shoe. Such invention may be used for the
purpose of monitoring forces projected through the foot to the ski
or snowboard to the snow or an athlete shoe to aid in training and
performance evaluation, or to the sole of a shoe to allow analysis
or user gait in order to correct the user walking pattern or aid in
the recovery after physical injuries. Said analysis is achievable
by embedding a gyroscope, accelerometer, magnetometer, pressure and
force sensors into the insole (or sole) of the shoe to provide
measurement of foot rotational and lateral motions in relation to
forces transmitted from the foot. Furthermore, one or more
actuators are embedded in the shoe insole to provide haptic
feedback to the user foot. The motion and weight distribution
vectors are processed by the micro-controller embedded in the
insole, and the resulting motion matrices are transmitted to the
user smart-phone using Bluetooth, or other suitable short range
radio interface. Alternatively, the data from motion sensors may be
transmitted to the user smart-phone for processing of motion fusion
matrices. The results are synchronized to GPS time and coordinates,
then after applying appropriate filtering, transmitted to one or
more actuators embedded in the shoe insole, providing haptic
feedback to the user, indicating timing and direction of force
distribution required to execute turn or to correct running or
walking pattern. The results may also be transmitted to the remote
location ("cloud service") for further processing using user's
smart-phone cellular radio interface. Said processing includes
presenting of the foot motion and force distribution in a form of
animation and superimposition of motion and force data on the 3D
maps obtained from GPS coordinates. The post-processed visual and
numeric data may then be received from the cloud server by the user
smart-phone or by a remote computer terminal. Furthermore, if a
devotion, such as: accident; fall without recovery over certain
period of time is detected, an SMS message informing of such
situation is sent with the corresponding data to the predefined
recipients.
BACKGROUND
[0003] In skiing as well as gait analysis, monitoring of
performance relies on few techniques, such as: user feelings,
instructor/coach observations, etc, and some empirical factors,
such as: time measurements and video analysis, however, most of
those techniques are not practical for the every day training or
improve in diagnostics and recovery of physical injuries, as they
require bulky equipment, large team of highly skilled technicians
while lacking sufficient amount of data and have no ability to
provide corrective, real-time feedback.
[0004] The comfort, safety and pleasure of skiing or running or the
recovery period of motion skills are highly dependent on amount of
data; the quality of said data analysis; and the efficiency of the
corrective feedback. While most athletes relay on advise from a
coach, most recreational athletes relay solely of self-observation.
To analyze gait of individuals recovering from serious injuries or
of an athlete, a trained therapists obtain data in a controlled
laboratory environment employing several video or infrared cameras
placed around a walkway. The subject of analysis (patient or an
athlete) has markers located at various points of reference of the
body and data is collected, analyzed by professional who provides
feedback to the subject and/or therapist. To measure
kinetics--ground reaction forces, lab may have floor-mounted load
transducers. Due to complexity of the said measurement system,
collected data rarely correlates with normal activity of the
subject while the feedback is delayed. In the past, some innovation
in recording the pressure points projected by the foot on the shoe
insole were introduced in an attempt to analyze bio-mechanics of
training and gait. However, those devices record only distribution
of pressure while requiring synchronization with real-time video to
provide meaningful information. And as real-time video
synchronization is rarely available outside of the lab, the benefit
of such devices is very limited.
[0005] In recent years, the use of mobile devices and, in
particular, smart-phones proliferated, all provided by the progress
in electronics circuit integration. Today's smart-phone besides
providing communication over cellular network is equipped with
various input/output capabilities, such as wireless PAN (Personal
Area Network), and provides significant computing resources. Such
computing and communication resources may be integrated with a
motion analyzer embedded into replaceable sole of a ski boot, or a
walking/running shoe, or a skate boot, etc, to provide level and
quality of feedback suitable for all--from an athlete trying to
improve his performance to a patient trying to recover form an
injury. In such system, a motion and force analyzer embedded in the
insole communicating with the user smart-phone or a dedicated
cellular interface modem, provides capability to record, analyze
and visualize all characteristic movement, ground reaction forces
transferred to the user foot and to provide corrective feedback to
the user. The characteristic may be transmitted to the remote
location using smart-phone cellular radio interface and stored in
the "Internet cloud" for post-analysis or displayed in real-time in
a remote location. Such system can be used as an aid in instruction
or in recover, or as a tool in objective determination of athlete
performance--i. e. to determine quality of performance by the
free-style skier. Such system may operate using any of wireless
technology such as: cdma2000, UMTS, WiMax, LTE. LTE-A, etc.
SUMMARY OF THE INVENTION
[0006] This invention describes system which allows visualization
of user's foot motion in relation to the distribution pressure
points inside the shoe and to provide real-time corrective haptic
feedback by embedding miniature micro-mechanical systems (MEMS) and
electronics components into the inner sole of the shoe. The system
comprises of: 3-axis accelerometer, 3-axis gyroscope and a 3-axis
magnetometer, to provide motion vectors in 9-degree of freedom, to
obtain 3-D motion, and a multiplicity of force-pressure sensors--to
record forces transmitted from the foot to the insole or ground
reaction forces transmitted to the foot. In addition, an
atmospheric pressure sensor providing measurement of changes of
atmospheric pressure (to record vertical motion), may be added.
Such system provides measurement of linear acceleration, rotational
vectors and orientation (attitude) in three-dimensional space does
provides representation of motion in relation to ground reaction
forces. This motion and force vectors, synchronized with GPS time
and coordinates are sent to a remote location for processing and
presentation in visual and numerical form. Such presentation may be
used to understand the precise cause--in relation to time/position
to aid in training or to provide corrective feedback or provide
explanation of the nature of error and to suggest remedy. Such
corrective feedback may be in form of a feedback by a haptic
actuator located under the user's toe(s) to provide haptic
instructions how/when to change distribution of the forces in the
shoe. This feedback is based on the analysis of the: current phase
of the motion; information about the user and equipment and his
physical parameters: current distribution of force inside shoe; and
the knowledge of proper timing and the distribution of force
required to achieve smooth transition of the desired motion. In
addition, visual presentation of motion in 3D space and/or the
topological information is added, providing objective assessment of
the performance or rehabilitation.
[0007] The motion and force processing system of the present
invention comprises motion capture sub-system consisting of: a
multi-axis accelerometer; a gyroscope; a magnetometer (compass); a
barometric pressure; a multiplicity of force sensors; a
microprocessor; and a personal area network (PAN) radio interface
to communicate motion vectors to the smart-phone based
application.
[0008] According to first embodiment of this invention, the motion
and force processing system is embedded in a replaceable insole of
the ski boot inner-lining or directly embedded in the ski boot to
analyze the motion of skis in relation to the location and value of
force transferred by the skier feet to the insoles of the ski boot
and the timing such force is applied.
[0009] It is well understood how ski or snowboard turns when
moments are applied to the ski edge by skier's body through the
forces applied to the skier's foot, and how the turning performance
is determined by said forces and the reactions introduced by
ski-snow contact. Understanding of skiing bio-mechanics allows
determination of proper pressure distribution on the skier's foot
in order to make the foot pronate to control the external forces
that disturb equilibrium of balance. To establish balance platform,
skier must place the center of pressure on the outside (of the
turn) foot, and only in specific conditions during the turn. In the
foot/skiboot system, the center of pressure (COP), lays at the
point where the resulting force (F.sub.R) of interaction between
the ski and snow acting on a skier at ski between the turns (flat
phase of turn), pulls his center of mass (COM) downward towards the
snow and is opposed by muscles preventing a fall. Said knowledge
may be augmented with real-time tracking of ski boot motion and the
distribution of pressure points inside the ski boot during
difference phases of turn.
[0010] Analyzing motion, one may determine the current phase of the
turn and knowing the skier and equipment physical parameters may
predict (extrapolate) the desired rate of ski rotation, then
provide haptic stimulus indicating time the COP must be transferred
form one part of the foot to another part. Such system, comprising
motion and pressure sensors embedded in the ski boots and a
smart-phone based application may provide real-time feedback to the
skier and visual post-run analysis does provide tool in
training.
[0011] According to second embodiment of this invention, the motion
and force processing system is embedded in a replaceable insole of
the walking or running shoe to analyze gait and balance of user by
estimating vertical ground reaction force vector applied trough the
shoe insoles to user's feet and limbs in relation to feet motion,
then after said analysis provide haptic corrective feedback.
[0012] As the gait analysis is a function of modification of many
movement factors, the gait patterns can be transient or permanent.
As such the gait analysis system of this embodiment can aid both to
provide information of natural abnormalities and help selection of
suitable prosthetics, as well as in rehabilitation of a temporary
gait abnormalities during the recover from physical injuries, such
as cerebral palsy or recover of stroke patient, or add in training
in order to optimize athlete performance.
[0013] This embodiment of the invention, allow for the assessment
of gait disorders and effects of corrective orthopedic surgery, as
well as to help in selection of options for treatment and
correction of distorted bony anatomy such as a misaligned pelvis or
sacrum.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] A better understanding of the present invention can be
obtained when the following detailed description of the preferred
embodiment is considered in conjunction with the following
drawings, in which:
[0015] FIG. 1A, is an exemplary skiboot haptic feedback system;
[0016] FIG. 1B, is an exemplary gait analysis haptic feedback
system;
[0017] FIG. 2, depicts an innersole and the components of the
exemplary haptic feedback system;
[0018] FIG. 3, presents a cross-section of the innersole;
[0019] FIG. 4, presents relation between the skier's foot and the
components of the skiboot innersole;
[0020] FIG. 5, depicts an exemplary architecture of the haptic
system controller;
[0021] FIG. 6A, presents skier foot bio-mechanical pressure
points;
[0022] FIG. 6B, presents the center of force (COF) point under the
heel and it's forward transition to become center of pressure (COP)
in the phase between two consecutive turns;
[0023] FIG. 6C, presents the COP position at the end of the turn
when it lays over the top of the inside ski edge and on the same
axis as the center of mass (COM) resulting force (F.sub.R);
[0024] FIG. 7A, presents the incorrect migration of the COF during
turn from the foot heel to the head of the second toe;
[0025] FIG. 7B, presents the migration of the COF back from the
incorrectly placed COF to the center of the foot and back to the
heel;
[0026] FIG. 8, presents the orientation of the motion sensors
(accelerometer, gyroscope, magnetometer), and their transformation
matrixes;
[0027] FIG. 9, presents the view of global coordinate system in
relation to ski slope;
[0028] FIG. 10, presents the view of local (skiboot) coordinate
system in relation to the ski slope;
[0029] FIG. 11, presents transformation of local coordinate system
during turn;
[0030] FIG. 12, presents a control process of the haptic feedback
system;
[0031] FIG. 13 presents the flow of the haptic system initial
calibration;
[0032] FIG. 14, presents graphical and numerical representation of
motion and pressure points transmitted to the skiboot insole by the
foot during a successful turn.
[0033] FIG. 15, presents graphical and numerical representation of
motion and pressure points transmitted to the skiboot insole by the
foot during an unsuccessful turn.
[0034] FIG. 16, presents another version of graphical
representation of motion in relation to the pressure points on the
skiboot insole.
[0035] FIG. 17, presents operation of haptic feedback actuator on
the outside foot during the transition into left turn;
[0036] FIG. 18, presents typical cycle of the gait in relation to
timing of cycle phases;
[0037] FIG. 19A, presents model used to analyze moments and forces
applied to joints'
[0038] FIG. 19B, presents an example of an analysis of ankle during
the stride with numerical data and in graphical form during
sampling time of the averaged gait cycle;
[0039] While the invention is susceptible to various modifications
and alternative forms, specific embodiments thereof are shown by
way of example in the drawings and are herein described in detail.
It should be understood, however, that the drawings and detailed
descriptions are not intended to limit the invention to the
particular form disclosed, but on the contrary, the intention is to
cover all modifications, equivalents and alternatives falling
within the spirit and scope of the present invention as defined by
the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
[0040] The following is a glossary of terms used in the present
application:
[0041] Haptic Feedback System--in the context of this invention is
a system able to collect and analyze motion and forces applied by
the user foot to the insole of the shoe, then after determination
of the phase of motion, apply a haptic feedback to the user's foot
indicating optimal distribution of the pressure points.
[0042] Application--the term "application" is intended to have the
full breadth of its ordinary meaning. The term "application"
includes 1) a software program, which may be stored in a memory and
is executable by a processor or 2) a hardware configuration program
useable for configuring a programmable hardware element.
[0043] Computer System--any of various types of computing or
processing systems, including mobile terminal, personal computer
system (PC), mainframe computer system, workstation, network
appliance, Internet appliance, personal digital assistant (PDA),
television system, grid computing system, or other device or
combinations of devices. In general, the term "computer system" can
be broadly defined to encompass any device (or combination of
devices) having at least one processor that executes instructions
from a memory medium.
[0044] Mobile Terminal--in the scope of this invention any wireless
terminal such as cell-phone, smart-phone, etc. provisioned to
operate in the cellular network.
[0045] Memory Medium--Any of various types of memory devices or
storage devices. The term "memory medium" is intended to include an
installation medium, e.g., a CD-ROM, floppy disks 104, or tape
device; a computer system memory or random access memory such as
DRAM, DDR RAM, SRAM, EDO RAM, etc.; or a non-volatile memory such
as a magnetic media, e.g., a hard drive, or optical storage. The
memory medium may comprise other types of memory as well, or
combinations thereof. In addition, the memory medium may be located
in a first processor in which the programs are executed, or may be
located in a second different processor which connects to the first
processor over a network, such as wireless PAN or WMAN network or
the Internet. In the latter instance, the second processor may
provide program instructions to the first processor for execution.
The term "memory medium" may include two or more memory mediums
which may reside in different locations, e.g., in different
processors that are connected over a network.
[0046] Near Field Communication (NFC)--in the scope of this
invention is a type of radio interface for near communication.
[0047] Personal Area Network (PAN)--in the scope of this invention,
is a personal are network radio interface such as: Bluetooth,
ZigBee, Body Area Network, etc.
[0048] Body Area Network (BAN)--in the scope of this invention is a
network of sensors attached to the user body communicating over
wireless interface.
[0049] Motion Monitoring System--in the scope of this invention is
a system able to collect various instantaneous vectors such as:
acceleration, angular orientation, geo-location and orientation,
then using various mathematical operations to provide visual
representation of the user's motion.
[0050] Ski Equipment--in the context of this invention, is any part
of equipment used by the skier, such as: skis, ski boots, ski
poles, ski clothing, ski glows, etc.
[0051] Equipment Parameters--in the context of this invention, is
ski or snowboard design and manufacturing parameters, such as:
length, weight, toe/center/tail, stiffness, etc. are extracted
after manufacturing and entered into application.
[0052] Turn Symmetry--in the context of this invention the level of
correlation between pressure levels and locations of the COF
applied during the left and right turn.
[0053] User Parameters--in the context of this invention, is user's
physical parameters, such as: weight, height, skiing competence
level, etc. entered by the user into the application using mobile
terminal user (UI) interface.
[0054] Software Program--the term "software program" is intended to
have the full breadth of its ordinary meaning, and includes any
type of program instructions, code, script and/or data, or
combinations thereof, that may be stored in a memory medium and
executed by a processor. Exemplary software programs include
programs written in text-based programming languages, such as C,
C++, Visual C, Java, assembly language, etc.; graphical programs
(programs written in graphical programming languages); assembly
language programs; programs that have been compiled to machine
language; scripts; and other types of executable software. A
software program may comprise two or more software programs that
interoperate in some manner.
[0055] Topological Information--in the context of this invention,
information about the topology of the ski slop obtained through any
combination of techniques such as: topography maps, GPS,
Radio-Telemetry, barometric pressure monitoring, etc.
[0056] User--in the context of this invention, person actively
using haptic feedback system.
[0057] Center of Pressure (COP)--in the context of this invention
is a point location of the vertical ground reaction force vector.
It presents a weighted average of all pressures over the surface of
the foot that is in contact with the ground.
[0058] Center of Mass (COM)--in the context of this invention is a
point equivalent of the total body mass in the global reference
system and weighted average of the COM of each body segment in
3Dimensional space.
[0059] Center of Force (COF)--in the context of this invention a
point location of a force applied by skier's foot to the insole
surface when the whole ski lies flat and in contact with the snow
surface reaction force. Said force location is calculated from
pressure data obtained from sensors located inside the skiboot
insole and reflect neutral control of ankle muscle.
[0060] Cloud Server--in the context of this invention is a
computing equipment allowing a client application software to be
operated using Internet enable devices.
[0061] Accelerometer--in the context of this invention is an
inertia based device measuring acceleration component based on
device motion and gravity.
[0062] Gyroscope--in the context of this invention is a sensor to
measure an angular rate of change in device orientation
irrespective to gravity.
[0063] Magnetometer--in the context of this invention is a sensor
to measure magnetic field by computing the angle of the Earth
magnetic field and comparing that measurement to the gravity
measured by an accelerometer.
[0064] Pressure Sensor--Atmospheric--in the context of this
invention is a sensor measuring the differential or absolute
atmospheric pressure and used to track vertical motion.
[0065] Force Sensor--in the context of this invention is a sensor
(resistive, capacitive, etc.), used to measure pressure (in
Netwons) of a foot on the insole of the skiboot.
[0066] Rotation Vector--Angular Velocity--in the context of this
invention is a vector quantity whose magnitude is proportional to
the amount or speed of a rotation, and whose direction is
perpendicular to the plane of that rotation.
[0067] Rotation Matrix--in the context of this invention is a
matrix that is used to represent rotation in Euclidean space and to
describe device orientation.
[0068] Gravity--in the context of this invention is Earth's gravity
measured in m/s.sup.2 and excluding acceleration caused by the user
and consisting of a relative angle between device and gravity
vector.
[0069] Orientation (attitude)--in the context of this invention is
an orientation of the device expressed in Euler angles, rotation
matrix or quaternion.
[0070] Motion Sensor Fusion--in the context of this invention is a
method to derive a single estimate of device orientation and
position by combining data from multiplicity of sensors.
[0071] Global Coordinate System--in the context of this invention
is a x/y/z coordination system referenced to the earth magnetic
field and in angle of inclination dependent on geographical
location.
[0072] Local Coordinate System--in the context of this invention is
a x/y/z coordinate of the motion sensor located skiboot, where the
x-axis is a horizontal and points to the toe of the skiboot, the
y-axis is a horizontal and points to the left and the z-axis is
vertical and points up.
[0073] Euler Angles--in the context of this invention is a three
angles introduced by Loenard Euler to describe orientation of a
rigid object using sequence of three consecutive rotations.
[0074] Quaternion--in the context of this invention is a
mathematical expression used to calculate rotation state of the
device using the axis and angle of rotation.
DESCRIPTION OF PREFERRED EMBODIMENT
[0075] This embodiment comprises a skiboot (or ice-skate boot)
insole configured to measure distribution of forces transmitted to
the skiboot insole during downhill run, a 3D motion processing
element, a linear resonant actuator to provide feedback to the
skier's foot and a wireless personal are network (PAN)
transceiver--such as: Bluetooth, ANT, etc., communicating force and
motion data to the smart-phone based application. Based on the
knowledge of skiing bio-mechanics, and the information received
from the skiboot insole, the smart-phone based application predicts
the intended ski trajectory, then provides haptic feedback to the
foot of the skier, suggesting proper distribution of pressure
points on the insole. Furthermore, the smart-phone application
transmits the pressure and motion data obtained form the skiboot
insole together with the GPS timing and coordinates to the remote
location for post-processing using wireless cellular network.
During post-processing, a 3D map based on GPS coordinates is
retrieved and superimposed on the motion/pressure data, which may
be provided in real-time on a remote computer or a smart-phone.
Alternatively, post-processed data may be stored on the remote
server and retrieved later by the user.
[0076] The insole of the present invention comprises several
Microelectromechanical (MEMS) motion processor, providing
capability of measuring motion in 10-degree of freedom. Said
capabilities are enabled by integrating a 3-axis accelerometer, a
3-axis gyroscope, a 3-axis magnetometer (compass), and a barometric
pressure sensor, then process the vectors obtained from said
sensors by one of well known motion fusion algorithms. In addition,
to motion processing, two or more force pressure sensors are also
embedded in the sole, said pressure sensors record the force
applied to the pressure point on the insole. When the change in
distribution--migration of the center of force (COF), is combined
with the motion data, we can obtain the phase of the turn the skis
are in, then scaling such results by user and equipment information
(weight, height, ski side-cut radius, etc.), provide feedback to
the skier's foot indicating timing of change and the amount of
pressure necessary to obtain desired turn, while recording said
pressure, motion and errors.
[0077] Most skiers have an intuitive understanding of skiing,
gained from practice and understanding some of the physics behind
skiing. Such understanding is useful to skiers of all levels, as it
identifies key principles, enabling to properly execute certain
movements to improve performance. In general, skiing (downhill),
involves high speed run down the sloped terrain using quick turns.
The skier gains speed by converting gravitational potential energy
into kinetic energy of motion, so the more a skier descends down a
heel, the faster he goes. A skier maximizes his speed by minimizing
resistance to motion, both from air resistance and snow resistance.
While the skier minimizes his air resistance (drag) by reducing his
projected frontal area, the reduction of snow resistance requires
combination of balance and subtle technique of turn. While the turn
is essential to go around objects of gates and arrive safely at the
bottom of the slope, the turn itself introduces resistance and as
such slows the skier. This is particularly pronounced by less
experienced skiers, as they skid around their turns and the skis
are tilted on their edge and skis plow into the snow. Also, in some
cases, a degree of skidding is unavoidable, more advanced skier,
will attempt to carve around the turn using skis natural shape
(side-cut), and flexibility. To help in "carving the turn", skier
will tilt the skis on the inner edge of the turn, and in general,
the larger is the angle between the snow and the ski surface, the
tighter the turn is. When the ski is flat on the snow, the radius
of the carved turn R.sub.T equals the side-cut radius R.sub.SC, and
the ski turns without skid as it travels in the same direction as
its velocity.
[0078] However, skid is an important technique used to suddenly
change direction, slow the speed or even stop. And unlike carving
where a skier eases into the turn, a skidded turn is initiated by
simultaneously tilting the edge of skis into the snow and pivoting
in the direction of the turn. This results in turning in that
direction, due to the plowing effect, since the skis are pointed in
a direction that is different from the initial velocity. The
steering angle determines sharp is the turn, and the loss of
velocity. A steering angle of zero results in the skier moving in a
straight line with no turning and no slowing down. A steering angle
of 90.degree. results in the skier slowing down with no turning,
since the force of the snow plowing into skis without sideway
component necessary for turn.
[0079] By measuring motion of the foot with 9-degree or 10-degree
of freedom, one can monitor motion in 3D, then using knowledge of
skier and ski physical parameters predict the progress of motion by
extrapolation.
[0080] In general, downhill skiing comprise straight skiing with a
flat skis between two consecutive turns, and the intrinsic skill
necessary for skiing is the maintenance of balance. Balance is
maintained by the skier's foot, which through numerous joints,
tendons, muscles provides receptive field for two main balance
metrics--Center of Mass (COM) and Center of Pressure (COP). In this
context, the process of skiing may be divided into three phases:
1.sup.st--initiate transition of balance (initiate turn);
2.sup.nd--ski flat (flat ski between turns); 3.sup.rd--rotate
pelvic (start next turn). All these phases are initiated and
maintained through changes in the distribution of foot COP and
application of said pressure to the skiboot through the skiboot
insole.
[0081] Without much generalization, it is possible to say that the
COP during the turn is located on the outside foot of the turn,
while during the flat ski phase (between turns), it is distributed
evenly between both feet and the net COP lies somewhere between the
two feet depending on the relative weight taken by each foot.
Furthermore, we may say that the location of COP under each foot is
a direct reflection of the neural control of the ankle muscles. The
location of COP under each foot is a direct reflection of the
neural control of the ankle muscles. Any movement that flexes the
foot or toes downward toward the sole (plantar flexion), will move
the COP toward back of the foot, while movement of the foot in
upward direction (dorsiflaxion), will move COP toward the front of
the foot, the movement of foot inward (invertor), moves COP towards
the outside of the foot.
[0082] The position of COP can be obtained by placing two or more
pressure sensors in the skiboot sole, then synchronizing the
changes in COP with the motion vectors obtained from the 3D motion
monitor. The knowledge of place the COP is at the present time
combined with the knowledge of past trajectory, present orientation
in 3D space, motion vectors and the location of COP allows
prediction of the future ski trajectory. Such trajectory may be
changed or influenced by the change in pressure applied to the
foot--thus influencing change of COP and in turn change of turn
parameters. Such "advise" about the timing and need to change
location of COP can be provided through feedback to the skier
foot.
[0083] This invention describes a system capable of monitoring
motion of the skier foot in relation to the snow, measuring the
location and distribution of force--pressure point(s), inside the
ski boot and provide haptic feedback to the skier's foot,
instructing on the time and direction the center of force (COF)
must be moved for the optimal execution of the current turn. Such
system comprises a skiboot insole for processing of motion and to
provide haptic feedback, a smart-phone based monitoring application
communicating with the insole using Bluetooth (or other suitable),
personal area network (PAN) wireless technology, and with the cloud
based server using cellular wireless technology.
[0084] The exemplary system is presented in FIG. 1A. Here an insole
100, of a ski boot 110, with an insole 100, communicates with a
monitoring application 300, hosted in a smart-phone 200. The
monitoring application 300 pre-processes the motion and pressure
data, retrieves a GPS time and coordinates from the smart-phone and
sends said data using smart-phone cellular radio interface 221, to
the cloud service 500, for further post-processing, while the
pre-processed motion and pressure data are used to provide haptic
feedback to the actuator located in the insole. Based on GPS
coordinates extracted from data, the cloud server retrieves 3D map
of the area, then superimposes the graphical and numerical
parameters of the run on said 3D map. This map, together with the
graphical and numerical parameters of the run may be displayed on
the remote computer or viewed on the user smart-phone.
[0085] Skiboot insole 100, presented on FIG. 2 and FIG. 3,
comprises of a lower 101, and upper 102, insole surfaces and a
motion processing and feedback sub-system 103, sandwiched in
between insole surfaces. The motion and feedback sub-system consist
of a motion processing element 1031, two or more pressure/force
sensors 1032, and a haptic actuator 1033. The motion processing
element 1031, is configured for analysis of motion with 10-degree
of freedom comprising several inertial MEMS sensors: a 3D
gyroscope; a 3D accelerometer; a 3D magnetometer (compass); and an
atmospheric pressure sensor.
[0086] The 3D gyroscope is used to measure angular rate change by
the insole in degrees per second, thus allowing measurement of
angle, travel and as such, track changes in the insole orientation
(pitch, roll and yaw angles). The accelerometer is used to measure
acceleration of the insole caused by motion due to gravity in an X,
Y, Z coordinate system by computing the measured angle of the
device, compared to gravitational force and the results are
expressed in m/s'. By integrating acceleration vector a(t) over
period of time, we obtain velocity function v(t). The 3D
magnetometer measures the earth magnetic field at specific
location. By computing the angle of the magnetic field, and
comparing that angle to gravity obtained from accelerometer, we are
able to determine the orientation of the insole with respect to
magnetic North. Beside, sensing the direction of earth magnetic
field, magnetometer is used to eliminate drift of gyroscope.
Furthermore, the insole motion processing element employs an
atmospheric pressure sensor to obtain changes in the altitude and
rate of descent by detecting ambient air pressure (P.sub.amb)
according to equation:
h.sub.alt=(1-(P.sub.amb/10132).sup.0.190284)*145366.45
to track vertical motion.
[0087] By observing three-dimensional vector of gravity measured by
the accelerometer along with measurements provided by gyroscope, we
can determine orientation of the ski (pitch, roll, yaw), while the
skier is in motion. Also by subtracting gravity vector form
acceleration, we obtain linear acceleration of the ski. The
orientation angles describe motion, and are used to provide
graphical representation of motion. Furthermore, we derive a
rotation vector from results provided by accelerometer, gyroscope
and magnetometer. This vector represents a rotation around a
specific axis and corresponds to the components of a unit
quaternion, which represents yaw, pitch and roll and is used to
graphically represent motion of the insole.
[0088] The quaternion of the insole (and skiboot), is calculated
by, first converting gyroscope angular rate to a quaternion
representation:
dq(t)/dt=1/2.omega.(t)*q(t),
where .omega.(t) is the angular rate of motion and q(t) represents
normalized quaternion. Then, we convert the accelerometer results
from local coordinate system, represented as A.sub.L to global
coordinate system, represented as A.sub.G, by using previously
obtained quaternion as:
A.sub.G(t)=q(t)*A.sub.L(t)+q(t)'.
[0089] Then calculate acceleration quaternion as:
qf(t)=[0A.sub.Gy(t)-A.sub.Gz(t)0]*gain
which is added as a feedback term to quaternion from gyroscope,
then add magnetometer data to the azimuth (yaw) component of the
quaternion.
[0090] The exemplary skiboot insole motion processing and feedback
sub-system 103, is presented in FIG. 4, and comprises of: a motion
processing element 1031, comprising a 3-axis accelerometer, a
3-axis gyroscope, a 3-axis magnetometer and a barometric pressure
sensor. In addition, the motion processing and feedback sub-system
consist of several force pressure sensors 1032, a haptic feedback
actuator 1033, a Bluetooth RF interface 1036, and microprocessor
1034 with it's program memory 1035. The sensors within the motion
processing element 1031, are connected to the microprocessor 1034
using one of appropriate digital interfaces, such as I2C, or an
appropriate analog interface. Similarly, the force pressure sensors
may be connected to the microprocessor analog-to-digital (ADC)
converter using appropriate analog interface or directly to the
microprocessor digital interface, while the haptic feedback
actuator may be connected to the microprocessor digital-to-analog
(DAC) converter.
[0091] The relation between skier's foot 710, and the skiboot
insole 100, is presented in FIG. 5. During the run, the location of
the pressure points to the skiboot/ski and the distribution of
pressure (force) between both feet provides the kinetic mechanism
necessary to initiate and end a turn. While between
turn--frequently referred a `flat ski`, the force is distributed
equally between both feet and equally between front and back of the
foot, the location of the pressure points between the feet and
inside the skiboot changes during the turn. From FIG. 5, one may
observe two main location of the force--at the front of the foot
(F.sub.Toe) 104, and the back of the foot (F.sub.Heel) 105. The
actual location of those pressure points and consequently the
location of center-of-force (COF) may be measured by two or more
force sensors 1032. The haptic feedback 106, to the skier foot is
provided by actuator 1033.
[0092] Each turn in skiing may be separated into three phases: 1)
ski flat phase; 2) start of transition phase; 3) pelvic leg
rotation phase. During the ski flat phase, the skier COF is
distributed evenly between both skis and located in a neutral point
(evenly distributed between toe and heel of the insole). The skier
selects inner ski--effectively selecting direction of the turn, and
start the transition phase. At this moment, the COF of the inner
foot migrates toward the pinky toe and initiated forward movement
on the "new" outer ski, this moves the COF of the outer foot toward
the big toe. Then enters the third phase by rotating his leg pelvic
moving the COF firmly on the outer ski which places the resulting
force F.sub.R on the edge of the outer ski.
[0093] For the outer ski, this process is presented in FIGS. 6A, 6B
and 6C and described below. In FIG. 6A, the foot 710, during the
flat ski phase between edge change, the pressure is distributed
evenly between two main mechanical points 720 located at the heel
on the centered axis 711, and on the center of head of the 1.sup.st
metatestral (MT) bone 730, of a foot and centered along the inside
edge 712.
[0094] The start of transition is presented in FIG. 6B, here, when
the COF 740 is located under the skier heel and progresses forward
to position 742,--the head of the 1.sup.st MT. The COF essentially
"rolls" inwards, the ankle is plantar flexed and the foot is
inverted, the leg rotates while COF moves forward along arc 741,
towards the head of the first MT. When the head of the first MT is
maximally loaded (FIG. 6C), the COF and the skier fully rest on the
outer foot (monopedal stance), while the resulting force F.sub.R
760 align with the COF above the edge of the outer ski 750. At this
moment, the rolling of the foot inwards generates torque, which is
directed into turn.
[0095] When the distribution of pressure between skis or the
transition of COF from the heel of the outer foot to the head of
1.sup.st MT fails, the turn is unsuccessful and skier looses his
balance. The graphical representation of such turn is presented in
FIGS. 7A and 7B. At some point between the edge change but before
the new outside ski attains significant edge angle (without
necessary plantar flex of an ankle), a moment develops between the
inside edge of the ski and the COF resulting in inversion moment of
force. Torque associated with vertical axial rotation of the leg,
FIG. 7B, will reverse the movement of the COF 745, to the point of
origin 720 as it is aligned with the heel and lower limb. Such
reverse can't be stopped and skier looses his balance.
[0096] An exemplary orientation of motion sensors within the insole
and it's relation to their respective matrix is presented in FIG.
8. This relation is important to establish local coordinate system,
as the matrix obtained from different sensors will rotate depending
on insole orientation in reference to the global coordinate system.
The motion processing element 1031, embedded in the skiboot insole
100, and comprises of: 1) an accelerometer 800, which Y axis points
to the left side of the insole, the X axis points to the front of
the insole and the Z axis points up; 2) a gyroscope 810, which Y
axis points to the left side of the insole, the X axis points to
the front of the insole and the Z axis points up; and a
magnetometer 820, which Y axis points to the back of the insole,
the X axis points to the right of the insole and the Z axis points
down. Related to this orientation of sensors are respective
matrixes: 801, 811 and 812.
[0097] The insole global coordinate system is established in
reference to the earth magnetic field at the specific geographical
location obtained from the magnetometer 820, by comparing it's
angle to gravity measured by accelerometer. The orientation of the
global coordinate system 900, to the slope 910, with an incline a
911, is presented in the FIG. 9. Here, the Z axis is perpendicular
to the ground and the negative Z points in direction of earth
gravity. The X axis points to East and the Y axis points to
magnetic North. After the global coordinate system is established,
the local coordinate system 901 in FIG. 10, a coordinate system of
the insole in relation to the global coordinate system may be
calculated by reading measurement form accelerometer and
gyroscope.
[0098] The method of presenting motion and orientation of the
insole and by extension ski in the 3D space can be explained based
on FIG. 11 and the processing allowing visualization of said motion
described in the following sections. Here at time t.sub.0, the ski
is flat and with the X axis pointing horizontally in the direction
of slope line. The Y axis points to the left, while the Z axis
point upward. After start of transition, at time t.sub.1, ski
rotates along the Z axis by angle .PSI. (yaw), 905, and along the X
axis by angle .theta. (pitch), 903, and along the Y axis by angle
.PHI. (roll), 904, into left turn. This motion may be described in
terms of Euler Angles using Euler motion theorem as three
consecutive rotations of coordinate system
xyzx'''y'''z'''x''y''z''x'y'z', where the 1.sup.st rotation is
along the z-axis, 2.sup.nd rotation is along the former x-axis and
3.sup.rd rotation is along the former y-axis.
[0099] The insole orientation may also be described in terms of
matrix rotation. For a 3D matrix the rotation .theta. (pitch), may
be described as:
R .theta. = [ cos .theta. - sin .theta. 0 sin .theta. cos .theta. 0
0 0 1 ] ##EQU00001##
[0100] so the vector V.sub.0=[1,2,0].sup.r will become v'-[cos
.theta., sin .theta., 0].sup.r. As the rotation matrix are
orthogonal with detriment 1 and with own transpose and an inverse,
the rotation matrix will reverse its rotation when multiplied with
the rotation inverse. We can also use the matrix rotation to obtain
direction of earth gravity in relation to orientation of the
insole. When the insole change orientation, its Z axis moves from z
to z' by rotation matrix A, according to: z'=A*z. As for the local
(insole) coordinate system the z' vector is [0, 0, 1].sup.r, the
vector z is obtained by the inverse of rotation matrix.
[0101] Rather then use computationally intensive matrix rotation to
obtain insole orientation, we may use mathematical expression of
quaternion to calculate insole rotation state according to Euler's
rotation theorem stating that device orientation may be expressed
as rotation about one or more axis. This axis representing unit
vector magnitude and angle remains unchanged--except for the sign,
which is determined by the sign of the rotation axis represented as
three-dimensional unit vector =[e.sub.x e.sub.y e.sub.z].sup.T, and
the angle by a scalar a.
[0102] Calculation of quaternion requires only four terms when the
axis and angle of rotation is provided. Quaternion extends complex
numbers from two-dimensions to four-dimensions by introducing two
more roots of -1 as:
i.sup.2=j.sup.2=k.sup.2=ijk=-1
which are then multiplied with real components as:
r+ix+jy+kz
then conjugate and normalize to arrive with unity |u|=1, or
quaternion.
[0103] Operations and procedures of said system is presented in
FIGS. 12 and 13 and described in details in the following sections.
In FIG. 12, upon initial power-up and association of the insole
Bluetooth transceivers with the application, the system control
program checks if this is 1.sup.st run 1200, indicating the initial
calibration procedure was executed. Depending on user parameters,
such calibration may be performed during the first run of the day,
or at the request by the user, to allow for adjustments to the
changing snow conditions, etc. If this is the 1.sup.st run,
application enters the initial calibration routine of FIG. 13,
otherwise, user is given an option to update through the
smart-phone user interface (UI), to update one or all system
parameters. If said option is rejected, application enters the main
control loop, otherwise, the user is prompted to select which
information--first (user parameters), second (equipment
parameters), or third (snow condition parameters).
[0104] The First information 1201, comprises of user parameters
consisting among the others: body weight; height; and skiing
proficiency level--"beginner", "intermediate", "advanced",
"professional".
[0105] The Second information 1202, comprises technical parameters
of the user equipment, consisting among the others: length of the
ski; ski natural turn radius (side-cut); etc.
[0106] The Third information 1203, comprises the snow conditions
present during the calibration run, such as: "groomed slope",
"icy", "powder". This information is used to derive two
coefficients--first, to scale the time between the start of
transition and when the COF reaches position 742 (FIG. 6B); second,
to scale the distribution of COF between inner and outer ski.
[0107] The second and third information may be entered by the user
manually or scanned to the application from the QR-code or NFC
parameter tag attached to the equipment.
[0108] The initial calibration procedures comprises of 8 steps
which are described in FIG. 13, and in the following
paragraphs.
[0109] In Step 1, user is instructed to enter his physical
parameters, such as weight, which is used to calculate the
distribution of force between both skis using Newton's Second Law
as well as calculating distribution of force inside the
skiboot.
[0110] In Step 2, user enters equipment parameters by either
scanning a QR-code or a NFC tag attached to the equipment or
manually using smart-phone UI. Among the others, some of parameters
like the length and the turning radius or, side-cat of the ski are
important factors used in conjunction with motion vectors to
calculate the ski effective turning and derive an optimal turning
radius during turns.
[0111] In Step 3, user enters the current snow condition of the
slope. This is used to appropriate scale the pressure point
(weight) distribution and timing of COF change in different
condition of the slope, for example change of technique between
powder skiing and skiing on icy snow.
[0112] In Step 4, application instructs the user to step into the
skis and reads data from motion sensors for the purpose of
establishing global and local coordinate system, then in Step 5
instructs the user to perform several exercises: [0113] 1) Stand in
normal, relaxed bi-pedal position with body weight equally
distributed between both skis, then record the force [N], measured
by each pressure force sensor; [0114] 2) Stand in a crouching
position, leaning forward and elbows resting on the knees, then
record the force [N], measured by each pressure force sensor;
[0115] 3) With both skis parallel and without support of the ski
poll, bend knees and push inward (as during sharp turn with both
skis on the edge), then record the force [N], measured by each
pressure force sensor; [0116] 4) Instruct user to make a run
consisting at least four carved turns. Allow for the ski to
accelerate by ignoring first two turn, then record motion
parameters during two consecutive turns; [0117] 5) End calibration
procedure.
[0118] After power ON, the MCU 1034, enters standby mode and
remains in said mode until an interrupt from the insole pressure
sensor is above threshold pTh_1, indicating both of user feet are
in the skiboot and on the ground. If new calibration is not
required, system enters normal operation, FIG. 12, Step 1, obtains
global and local coordinate system, then enters Step 2. In Step 2,
system starts monitoring motion, and if the velocity exceeds
threshold vTh_1, indicating start of the run, enters into Step 3,
then start sending motion and forces data to the smart-phone
application over radio interface 211. System remains in State 3,
until velocity of the system is above threshold vTh_2 and the
pressure force measurement is above threshold pTh_2. When the
velocity is below threshold vTh_2 and pressure forces is below
threshold pTh_2, indicating end of day (skiboot off), or time-brake
in skiing (lift, rest, etc.), system enters Step 4, stops
processing of motion and forces, forces radio interface transceiver
1036, into power OFF mode and MCU 1034, into a standby mode--thus
conserving power consumption of the system. After exiting Step 4,
system remains in the sleep mode until condition of Step
2--pressure force above pTh_1 and velocity above vTh_1 conditions
are not satisfied.
[0119] The motion and pressure force data received from the insole
100, by the smart-phone 200, is processed by application 300 to
provide user with the haptic feedback. Based on signal from
sensors, using inertia navigation algorithms, application
calculates kinematics of the ski trajectory. Then using user
parameters, creates biomechanical model of foot/ski interface, and
the sensor kinematics is translated to segments kinematics by
measuring the position (and timing) of COF. Such calculation
provides two results: one, current ski trajectory; two, prediction
of future trajectory in relation to the local coordinate system and
location of COF. The first set of results are sent to the cloud
based server 500 for further processing using smart-phone cellular
radio interface 221, while the second sets of results is used to
provide corrective feedback to the user foot.
[0120] This corrective feedback is in form of haptic pulses applied
by the haptic actuator to the big toe of the foot. This feedback
provides information of timing, direction and destination of the
COF necessary to successfully start and finish turn. This feedback
may be coded in various ways, for example, different frequency
and/or force during different phases on turn, etc.
[0121] Operation of said haptic feedback is presented in FIG. 17.
Here we see the outside (of the turn) foot 710, right after start
of transition, which the haptic feedback actuator 800, vibrating at
high frequency (or force), when the COF is still located under
skier heel, indicating time to transition on the outside ski and
move COF to the base of 1.sup.st MT. The vibration frequency may
decrease while COF moves forward to new position 741, and
completely stop when the COF reaches the desired position 742,
while never stop vibrating at high frequency when the COF fails to
reach the base of 1.sup.st MT.
[0122] Together with the first set of results, application sends to
the cloud server GPS coordinates and timing. The first set of data
is then used to generate a numerical and graphical presentation of
the run. An exemplary representation of run data is presented in
FIGS. 14, 15 and 16. Such run data may be retrieved form the cloud
server later by the user and displayed on the user smart-phone (for
example during the travel on the lift), or in real-time on a remote
computer. Furthermore, using the GPS coordinates, cloud server may
superimpose said data on 3D map of the terrain, giving additional
reference and meaning to the data.
[0123] After the post-processing of first set of results by the
remote cloud server, visual and numerical representation of the run
can be displayed on a remote computer or on a smart-phone. Among
the others visual presentation possible, some of the visual options
are presented in FIGS. 14, 15 a 16. FIG. 14, shows left and right
foot with a graphical representation of the location of COF and 3D
motion parameters in relation to the GPS time. Here we see the
movement of the COF 740 from the start of transition into the left
turn, the location of the COF 742 after the initial phase of the
turn and the time (in milliseconds), of the transition 770.
Furthermore, the calculated location of the resulting force F.sub.R
760, a point where the skier center of mass (COM) is acting on the
ski and snow.
[0124] The graphical and numerical results, representing
unsuccessful turn is presented in FIG. 15. Here we see the mistake
user makes during the start of transition (flat ski=>select new
ski=>COF of inner foot to head of 5.sup.th MT), inner foot COF
forward to the center of foot 744. In order to maintain balance the
COF of the outer foot was placed between 2.sup.nd 3.sup.rd MT 745,
and the resulting force moved to the outer edge of the outer foot.
In this position the body kinematics does not allow for pelvic
rotation and in effect, the COF return to the heels of the
feet--balance is lost, turn can't be finished until balance is
recovered during next flat ski.
[0125] Data are analyzed in relation to velocity, pitch and roll
and effective radius of the turn and other numerical results 780
and 790 for left/right foot respectively, and may be used by both
the amateurs to improve their skills, professionals during
training, judges in analyzing performance of a free style or figure
skating competition or even commentators during televised sports
events. Furthermore, those results may be sorted and presented in
various statistical formats selected by the viewer. An example of
such statistical analysis may be use in training and evaluation of
turn symmetry--one of most important parameter of measuring
progress of a professional skier. Turn symmetry, is term used to
describe a pressure applied during the left and right turn. The
closer is the distribution of pressures between inner/outer ski
during the left and right turns, the better will the skier perform.
Such analysis is currently limited to visual observation by the
coach of the racer during a run over a specific part of the slope
where the transversal angle of the slope maintains relatively
constant angle to the line of the slope. Such observation is
subjective, prone to errors and of limited value--as it's
impossible to evaluate the symmetry of pressure visually and
specifically on the slope with changing topographical
parameters.
[0126] Turn symmetry statistics can be performed as follows:
[0127] Log all left turns into LEFT SET, and all right turns into
RIGHT SET;
[0128] FOR each turn with .PHI..sub.L=.phi..sub.R OR
-.PHI..sub.L=+.PHI..sub.R OR ++.PHI..sub.L=-.PHI..sub.R (roll);
[0129] Extract pressure points and force data;
[0130] Sort pressure points and force data in the descending order
of difference.
Similar method may be used for numerous other parameters of the
run.
[0131] Different view of the data presented in FIG. 16, where both
feet are shown in relation to the global coordinate 900, the angle
.beta., 902 to the local coordinate X, pitch .THETA., 903, of the
ski (angle between X and X)', the roll inside the turn .PHI., 904,
the effective turning radius .omega., 960, and velocity V 970. The
location of resulting force F.sub.R in relation to the ski edge 750
is also presented.
[0132] Another embodiment of skiing analyzer feedback system may
employ direct control by an instructor of coach. Here, motion and
force sensors data is relayed by the smart-phone 200, to the remote
device 700, operated by instructor or coach, who maintains visual
contact with the user. On the device 700, data is processed by
application 300, enhanced with a user interface (UI), allowing to
manually control the haptic feedback actuator embedded in the user
skiboot insole. The input from the terminal 700, UI operated by
instructor, is send back over wireless cellular interface 400 and
221, to the user smart-phone 200 and then using the PAN wireless
interface 210 to the haptic feedback actuator 1033, located in
insole 100. Such embodiment allows the couch to directly influence
the user actions and tailor his training/progress according to
predefined plan or changing slope conditions.
DESCRIPTION OF ANOTHER EMBODIMENT
[0133] This embodiment comprises a motion and force processing
element and an haptic actuator element embedded in the user shoe
insoles configured to analyze gait and balance by estimating
vertical ground reaction force vector applied to the user feet and
limbs in relation to feet motion and to provide haptic corrective
feedback. In addition to motion, force and haptic elements, said
embodiment comprises a wireless personal area network (PAN)
transceiver--such as: Bluetooth, ANT, etc., used for transmission
of force and motion data to the smart-phone based application and
for reception of control signals intended for haptic feedback
actuators. Based on the knowledge of gait bio-mechanics, and
information received from the insoles, smart-phone based
application provides haptic feedback to the user feet, suggesting
proper timing and distribution of pressure points. Furthermore, the
smart-phone application transmits gait data and the user GPS
location coordinates to a remote location for post-processing using
wireless cellular network.
[0134] In general, gait cycle comprises of two phases: 1) Stance
Phase; and 2) Swing Phase, with the respective duration of those
two phases of 60% and 40% of the user gait cycle. Furthermore, each
phase of the cycle can be further divided into portions consisting
of double or single limb support. It is those portion of each phase
of the gait cycle, when the heel strikes the ground, limb swings or
terminates the swing which are analyzed providing location of user
Center of Mass (COM), and in conjunction with the location of
Center of Pressure (COP), present picture of user balance and gait
characteristics.
[0135] The position of COP can be obtained by placing several
pressure sensors in shoe sole, then synchronizing the changes in
COP with 3-dimensional motion vectors obtained from motion
processing element. Knowledge COP location in the past combined
with COP current location in relation to the movement of user in
3-dimensional space allows for prediction of movement of user feet
during the next gait phase or even next gait cycle. Such knowledge
may be used to provide a "advise"--in form of haptic feedback to
the user foot, instructing of location of pressure and the timing
said pressure must be applied in order to correct abnormal gait or
to improve it's efficiency.
[0136] The exemplary system is presented in FIG. 1B. Here an insole
100, of a shoe 111, communicates with a monitoring application 300,
hosted in a smart-phone 200. The monitoring application 300
pre-processes the motion and pressure data, retrieves a GPS time
and coordinates from the smart-phone and sends said data using
smart-phone cellular radio interface 221, to the cloud service 500,
for further post-processing, while the pre-processed motion and
pressure data are used to provide haptic feedback to the actuator
located in the insole. Based on GPS coordinates extracted from
data, a 3D map of the area may be superimposes on result graphical
and numerical parameters displayed on remote computer on user
smart-phone.
[0137] Gait analysis insole 100, presented on FIG. 2 and FIG. 3,
comprises of a lower 101, and upper 102, insole surfaces and a
motion processing and feedback sub-system 103, sandwiched in
between insole surfaces. The processing sub-system, presented in
FIG. 4, consist a motion processing element 1031, two or more force
sensors 1032, and a haptic actuator 1033 and a Bluetooth RF
transceiver 1036, a microprocessor 1034 and microprocessor program
memory 1035. The motion processing element 1031, is configured for
analysis of 3-dimensional motion comprises inertial MEMS sensors: a
3-axis gyroscope; a 3-axis accelerometer; a 3-axis magnetometer
(compass); and an atmospheric pressure sensor, with sensors
connected to the microprocessor 1034 using one of appropriate
digital interfaces--such as I2C, or an appropriate analog
interface. Similarly, the force pressure sensors are connected to
the microprocessor analog-to-digital (ADC) converter inputs using
appropriate analog interface or can be directly connected to the
microprocessor digital interface, while the haptic feedback
actuator may be connected to the microprocessor digital-to-analog
(DAC) converter.
[0138] By observing three-dimensional vectors of gravity,
orientation and azimuth one can determine current orientation of
user feet motion. Motion of user foot, is calculated by, first
converting gyroscope angular rate to a quaternion
representation:
dq(t)/dt=1/2.omega.(t)*q(t),
where .omega.(t) is the angular rate of motion and q(t) represents
normalized quaternion. Then, converting the accelerometer results
from local coordinate system, represented as A.sub.L to global
coordinate system, represented as A.sub.G, by using previously
obtained quaternion as:
A.sub.G(t)=q(t)*A.sub.L(t)+q(t)'.
and calculating acceleration quaternion as:
qf(t)=[0A.sub.Gy(t)A.sub.Gz(t)0]*gain
which is added as a feedback term to quaternion from gyroscope, and
follow with adding magnetometer data to the azimuth component.
[0139] Relation between ground force and user foot 710, is
presented in FIG. 5. Here the insole 100, comprising motion
processing element 1031, and force sensing elements 1032 and 1033
records the force F.sub.TOE, 104 and F.sub.HEEL, 105 applied by the
user toes and heel in reaction to ground force while recording also
the timing and location of the force in relation to 3-dimensional
motion of the foot--those obtaining the location of the
center-of-force (COF), and distribution of forces between feet.
[0140] Location of the pressure points is measured by force sensors
1032 placed inside the insoles. Said measurements end their
relation to motion vectors are used to obtain location of the
center-of-force (COF) and consequently the actual gait and are used
to derive correction feedback 106, through the use of haptic
actuator 1033.
[0141] Process of walking or running is presented in FIG. 18. As
the body moves forward one limb typically provides support while
the other limb is advanced in preparation for its role as the
support limb. The gait cycle 1800, is comprised of stance phase
1821, and swing phase 1811. The stance phase further is subdivided
into 3 segments: 1) initial double stance 1830; 2) single limb
stance; and 3) terminal double limb stance 1831. Each of double
stance phases accounts for approximately 10% of the gait cycle,
while the single stance typically represents about 60% of the total
gait cycle, and the swing phase the remaining of the gait cycle.
During double stance period, the two limbs do not typically share
the load of the user and slight variations occur in the percentage
of stance and swing in relation to velocity--with each aspect of
stance decreasing as walking velocity increases. The transition
from walking to running is marked by elimination of double support
periods. In a normal gait cycle, the two steps comprising the cycle
are roughly symmetric.
[0142] During walk or run, each stride contains eight relevant
phases, a single cycle of such stride or gait cycle 1800, is
presented in FIG. 18. Of those eight phases, five are allocated to
a stance (i.e. initial contact, loading response, mid stance,
terminal stance, pre-swing), 1820 and 1821 for the left and the
right foot respectively, with the remaining 3 phases allocated to a
swing 1810 and 1811 for the left and the right foot respectively.
The first two gait phases occur during initial double support 1830,
and include the initial contact with the ground and the ground
loading response. In the normal gait, the initial contact is
referred as a heel strike 1801 and 1802 for the right and the left
foot respectively, also, many patients recovering from injuries, or
with the gait pathology, achieve heel contact later in the cycle,
or not at all. Two phases located between the double support phases
are referred as a single support phase 1840 and 1841, for the left
and right foot respectively. The joint motion during the double
support phase allows transfer of weight from one to anther leg
while attenuating shock, preserving gait velocity, and maintaining
balance.
[0143] The swing phase corresponding to single support of the limb
currently supporting body weight consisting of first half with a
single support and termed mid-stance which is responsible
progression of the center of mass over the support foot and
includes heel rise of the support foot and terminates with ground
contact of the other foot. The final stance element--pre-swing, is
related functionally to the swing phase that follows and begins
with terminal double support and ends with toe-off of the limb.
[0144] Many user specific parameters, must be considered in gait
analysis. Some of those parameters, for example: the user weight of
sex, may be entered through the application User Interface (UI),
others, such as: the user's gait pathological conditions, may be
obtained during self-calibration procedures; while yet another--for
example: configuration of the terrain, speed of movement,
atmospheric conditions, etc. may be collected in real time from the
smart-phone GPS receiver and sensors.
[0145] User specific parameters comprise several information, such
as: 1) physical and physiological information; 2) physiological
information; 3) pathological information; and 4) static gait
information.
[0146] The first information comprises description of user physical
characteristics--sex (male/female); weight; height and a body-type.
The second information comprising description of user physiological
characteristics--distance from hip to knee, and knee to ankle. The
third information comprising description user pathological
characteristics--trauma/injuries, muscular abnormalities. The forth
information comprising description of normal, abnormal or
pathological gait is obtained by the system during calibration
procedures.
[0147] The first and the second information can entered through the
smart-phone user interface (UI). The third information can be
entered through the smart-phone UI, or downloaded from the remote
medical facility. The forth information is obtained by the analyzer
during initial calibration procedures.
[0148] During dynamic (walk, run) gait analysis the third
information obtained during static calibration which provides
empirical information of user posture, foot orientation, natural
distribution of pressure inside the shoe is used as a coefficient
in a filter (may be of an interpolating, or an extrapolating of a
Kalman form), which in turn may be used as an input to the haptic
stimulus function intended to modify the abnormality of gait--for
example: abnormal gait is due to an injury and needs to be
corrected.
[0149] The results of dynamic gait analysis provides values and
distribution of ground reaction force experienced by the user foot
in relation to feet motion in time, does providing full picture of
the user gait. Those results can provide an estimate of rotation
moments in each individual joint and used by the analyzer to
calculate--and communicate in form of haptic feedback, the proper
location of pressure the use must applied during the next gait
cycle. An exemplary presentation of the location and the
distribution of COF were discussed in detail in previous paragraphs
and are presented FIGS. 6A, 6B, 6C; 7A, 7B, 14 and 15, and the
model of joints (hip 1910; knee 1920, heel 1930, and toe 1940) used
to analyze moments and forces applied to joints is presented in
FIG. 19A. Assuming the knowledge of the user physical
characteristics (sex, weight, height, body type contained in the
first information), and his physiological characteristics (distance
from hip to knee 1912, and knee to ankle 1923), one knowing the
location, value and distribution of ground reaction force on the
user feet obtained from the force sensors; plus the phase of the
gait and timing obtained from the motion processing element; plus
the location and terrain characteristics obtained from the
smart-phone GPS receiver--may estimate forces and rotation vectors
present in each joint.
[0150] The results obtained in said analysis of gait may be
presented in various formats, for example: numerical; graphical or
statistical. An exemplary representation of said results is
presented in FIG. 19A and FIG. 1B. In this example, an analysis of
ankle 1930, during the stride with statistical numerical data 1931
is presented in graphical form, providing picture of load (force)
to the right ankle 1932, and the right ankle 1033 at each sampling
time of the averaged gait cycle.
[0151] When the gait analyzer residing in the user smart-phone is
enabled, the phone Bluetooth establishes wireless communication
with the left and the right shoe insoles. At this time analyzer
associates left and right insoles Bluetooth devices ID (such as the
device UUID identification), with the left/right foot and prompts
the user may to enter (or download): first; second; and third user
information. Then, prompts the user to perform calibration of his
natural stance--forth information.
[0152] This calibration is performed in two separate phases: first
phase--the insoles orientation within the specific user shoes is
calibrated to accommodate for a different type of shoes (walking,
running shoes, different inclination, tilt, etc.); second
phase--the user is instructed to step inside the shoes and retain
several predefined positions designed to obtain the distribution
weight between user feet, distribution of pressure pints within the
shoes, does obtaining the user natural posture as well as
verification of user's actual weight versus the weight recorded in
the first information. The results of this calibration are used to
define the difference between the user actual gait and the desired
gait. Such difference is entered as a coefficient into the Least
Mean Squares (LMS), or a Gradient algorithm or another appropriate
filter--such as Kalman filter, designed to minimize the difference
between the current gait and the optimal gate by stimulating
feedback function applied to the haptic actuators locate in the
insoles. Such feedback function may be delivered in form of haptic
pulses of various amplitudes and frequencies using vibrating
actuator located in a specific place inside the shoe insole--for
example under the user big toe, or by a multiplicity of such
actuators located in a designated areas of the insoles.
[0153] The motion and ground reaction force is processed against
the user body model obtained from the second information (user
physiological characteristics), using inertia navigation algorithms
and geometrical triangulation, translating sensors kinematics to
user body segments kinematics by measuring position (and timing) of
center of force (COF), and a biomechanical model of foot/surface
interface during gait cycle. The results may be uploaded to the
remote computer server for further processing or display using the
smart-phone cellular radio interface.
[0154] The numerical results may be stored in CSV or XLS file
formats and made available for visualization of the moments and
forces superimposed over graphical representation of human body
and/or over terrain or 3-D maps generated from collected GPS,
atmospheric pressure or other sensors data. Additionally, said
stored data can be viewed in wide range of statistical analysis
tools in form of graphs, distribution functions, etc.
[0155] What has been described above includes examples of aspects
of the claimed subject matter. It is, of course, not possible to
describe every conceivable combination of components or
methodologies for purposes of describing the claimed subject
matter, but one of ordinary skill in the art may recognize that
many further combinations and permutations of the disclosed subject
matter are possible. Accordingly, the disclosed subject matter is
intended to embrace all such alterations, modifications and
variations that fall within the spirit and scope of the appended
claims. Furthermore, to the extent that the terms "includes", "has"
or "having" are used in either the detailed description or the
claims, such terms are intended to be inclusive in a manner similar
to the term "comprising" as "comprising" is interpreted when
employed as a transitional word in a claim.
[0156] It is understood that the specific order or hierarchy of
steps in the processes disclosed is an example of exemplary
approaches. Based upon design preferences, it is understood that
the specific order or hierarchy of steps in the processes may be
rearranged while remaining within the scope of the present
disclosure. The accompanying method claims present elements of the
various steps in a sample order, and are not meant to be limited to
the specific order or hierarchy presented
[0157] Those of skill in the art would understand that information
and signals may be represented using any of a variety of different
technologies and techniques. For example, data, instructions,
commands, information, signals, symbols, etc. may be referenced
throughout the above description by other means.
[0158] Those of skill would further appreciate that the various
illustrative logical blocks, modules, and algorithmic steps
described in connection with the embodiments disclosed herein may
be implemented as electronic hardware, computer software, or
combinations of both. To clearly illustrate this interchangeability
of hardware and software, various illustrative components, blocks,
modules, circuits, and steps have been described above generally in
terms of their functionality. Whether such functionality is
implemented as hardware or software depends upon the particular
application and design constraints imposed on the overall system.
Skilled artisans may implement the described functionality in
varying ways for each particular application, but such
implementation decisions should not be interpreted as causing a
departure from the scope of the present disclosure.
* * * * *