U.S. patent application number 14/210469 was filed with the patent office on 2014-10-02 for system and method for detecting golf swing with a ball impact.
The applicant listed for this patent is Tommi Kasma, Tapani Rantakokko, Osmo Voutilainen. Invention is credited to Tommi Kasma, Tapani Rantakokko, Osmo Voutilainen.
Application Number | 20140297007 14/210469 |
Document ID | / |
Family ID | 48444964 |
Filed Date | 2014-10-02 |
United States Patent
Application |
20140297007 |
Kind Code |
A1 |
Voutilainen; Osmo ; et
al. |
October 2, 2014 |
SYSTEM AND METHOD FOR DETECTING GOLF SWING WITH A BALL IMPACT
Abstract
The invention relates to a method, system, detection apparatus
and computer program for recognizing a collision of a golf club
with a golf ball. In the invention the recognition procedure is
configured to be executed partly in a motion sensor (22) of a
detection device (2), party in the processor unit (20) of the
detecting device and a mobile information processing device (6).
The most complex processing and computation steps are executed in
the processor unit (60) of the mobile information processing device
(6). Due to the shared computations the result of the algorithm is
accurate. Also the power consumption of the detecting device (2) is
low which provides for a long operating time and accurate hit
detection at the same time.
Inventors: |
Voutilainen; Osmo; (Oulu,
FI) ; Rantakokko; Tapani; (Oulu, FI) ; Kasma;
Tommi; (Oulu, FI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Voutilainen; Osmo
Rantakokko; Tapani
Kasma; Tommi |
Oulu
Oulu
Oulu |
|
FI
FI
FI |
|
|
Family ID: |
48444964 |
Appl. No.: |
14/210469 |
Filed: |
March 14, 2014 |
Current U.S.
Class: |
700/91 ;
473/221 |
Current CPC
Class: |
A63B 2225/20 20130101;
A63B 69/3608 20130101; A63B 2225/54 20130101; G09B 19/0038
20130101; A63B 24/0003 20130101 |
Class at
Publication: |
700/91 ;
473/221 |
International
Class: |
A63B 69/36 20060101
A63B069/36; A63B 24/00 20060101 A63B024/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2013 |
GB |
1305733.6 |
Claims
1. A golf swing and ball hit recognition system comprising: a swing
detection device (2) configured to be attached to a golf player's
wrist or forearm, the detection device comprising: a battery (29) a
power/energy management circuit (21); a tag reader (23); a motion
sensor (22); a processor unit (20) comprising a memory unit (24)
including a computer program; the memory unit (24) and the computer
program configured to, with the processor unit (20), cause the
swing detection device (2) at least to process motion sensor (22)
data and; a wireless transceiver (28); and a mobile device (6)
comprising computer program to process motion data received from
the swing detection device (2), characterized in that the ball hit
recognition process comprises at least one detection stage in the
swing detection device (2) or in the mobile device (6) where a
particular detection stage (220, 240, 600) comprises a particular
gesture recognizer accomplished by program modules that are
configured to recognize particular golf swing sub-gestures (30, 40,
41) or a collision event (42) between a golf club and a golf ball
(31).
2. The system according to claim 1, characterized in that a
recognizer program module comprises a field-programmable gate array
(FPGA) or a software application.
3. The system according to claim 1, characterized in that the golf
swing and ball hit recognition procedure is divided into a
stillness recognizing phase (80-89), a swing recognizing phase
(112, 113), a collision recognizing phase (90-98, 116-117), and a
follow through recognizing phase (114, 115).
4. The system according to claim 1, characterized in that the
motion sensor (22) is one of the following: an accelerometer, a
combination of accelerometers, a gyroscope, a combination of an
accelerometer and a gyroscope, a magnetometer, or a combination of
a gyroscope and a magnetometer.
5. The system according to claim 1, characterized in that the
mobile device (6) is a dedicated device or a general purpose device
with added processing software.
6. The system according to claim 2, characterized in that the
gesture recognizers comprise at least one of the following program
modules: a first program module to detect a stillness sub-gesture
(30) preceding a swing sub-gesture (40, 41); a second program
module to detect a collision event (42) of the golf club with a
golf ball (31); a third program module to detect a swing gesture
including a combination of a backswing (40) and a downswing
sub-gesture (41), collision event (42), and a follow through
sub-gesture (43).
7. The system according to claim 6, characterized in that the first
program module comprises a stillness (30) recognizer configured to
detect device orientation (81, 82, 85, 86) and device stillness
(83, 87, 88).
8. The system according to claim 7, characterized in that the
orientation and stillness sub-gesture (30) recognizer comprises a
state machine with thresholds and timers configured to be executed
in the motion sensor (22).
9. The system according to claim 6, characterized in that the
second program module comprises a collision event (42) recognizer
configured to: stream data (90, 91) from a 3D motion sensor (22);
filter (92) data of the motion sensor with a bandpass filter;
vectorize (93) the data of X, Y, and Z axis of the 3D motion
sensor; compose (94) an absolute value from the motion sensor
vector data; filter (95) said absolute values with a low pass
filter; detect (96, 97) the collision with the ball from said data
stream of absolute values, and if detected; initialize (98) a data
transfer from the 3D motion sensor (22) to the mobile device
(6).
10. The system according to claim 9, characterized in that the
second program module further comprises a state machine with
thresholds and timers configured to be executed in the MPU (20) of
the swing detection device (2).
11. The system according to claim 6, characterized in that the
third program module comprises a collision event (42) recognizer
configured to: stream data from a 3D motion sensor (22) of the
swing detection device (2); filter data of the motion sensor stream
with a bandpass filter; vectorize said data stream; compose an
absolute value from the motion sensor vector data; filter said
absolute values with a low pass filter; stream the filtered values;
and detect a hit due to a peak found from stream of the filtered
values.
12. The system according to claim 11, characterized in that the
third program module further comprises a backswing recognizer and a
downswing recognizer configured to detect a backswing sub-gesture
(40), a transition between the backswing sub-gesture (40) and a
downswing sub-gesture (41) and to detect the downswing sub-gesture
(41).
13. The system according to claim 11, characterized in that the
third program module comprises a peak detector including a state
machine with thresholds, timers and filters that are configured to
be accomplished by the third computer program module when it is
executed in the CPU of the mobile device (6).
14. The system according to claim 6, characterized in that the
third program module comprising the collision recognizer is
configured to: stream data from the motion sensor; filter data of a
3D motion sensor with a bandpass filter; calculate
cross-correlation between the acquired signal and an example
collision signal, and; detect a hit due to a peak found from said
cross-correlation signal.
15. The system according to claim 14, characterized in that third
program module is configured to be executed in the CPU of the
mobile device (6).
16. A swing detection device (2) configured to be attached to a
golf player's wrist or forearm, the detection device comprising: a
battery (29); a power/energy management circuit (21); a club
identification reader (23); wireless transceiver (28); a motion
sensor (22); a processor unit (20) comprising a memory unit (24)
including a computer program module; the memory unit (24) and the
computer program module configured to, with the processor unit
(20), cause the swing detection device (2) at least to process
motion sensor (22) data, characterized in that a golf ball hit
recognition process comprises at least one detection stage in the
swing detection device (2) and that a first detection stage
comprises a particular gesture recognizer accomplished by program
modules that are configured to recognize at least a first golf
swing sub-gesture (30) and a second golf swing sub-gesture
(42).
17. The swing detection device according to claim 16, characterized
in that the program modules comprise at least a first program
module configured to recognize a stillness sub-gesture (30) when
the first program module is executed in the motion sensor (22).
18. The swing detection device according to claim 17, characterized
in that the program modules comprise also a second program module
configured to recognize a collision (42) of a golf cub (5) with a
golf ball (31) when the second program module is executed in the
processor unit (20) of the swing detection device (2).
19. The swing detection device according to claim 18, characterized
in that the second program module comprises a hit recognizer
configured to: stream data (90, 91) from the 3D motion sensor (22);
filter (92) data of the motion sensor with a bandpass filter;
vectorize (93) the data of the X, Y, and Z axis of the 3D motion
sensor; compose (94) an absolute value from the motion sensor
vector data; filter (95) said absolute values with a low pass
filter; detect (96, 97) the collision event (42) with the ball from
said data stream of filtered values, and if detected; initialize
(98) a data transfer from the 3D motion sensor (22) to the mobile
device (6).
20. A swing detection device substantially as any one embodiment
herein described with reference to the accompanying drawings.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority of corresponding UK
Application No. 1305733 filed Mar. 28, 2013 entitled "A SYSTEM AND
METHOD FOR DETECTING GOLF SWING WITH A BALL IMPACT".
FIELD OF THE INVENTION
[0002] The invention relates to a golf swing detection system, a
golf swing detection device and a computer program utilized in the
golf swing detection system.
BACKGROUND OF THE INVENTION
[0003] Golf assistants, caddies, enable professional players to
focus on their game. Caddies can take care of various game related
tasks during the round. The caddie may carry the bag, suggest club
selection based on player records, keep track on strokes and assist
in reading putting lines. Already before the game, the caddie can
be of help e.g. by supporting planning of the game strategy. In
many cases the player and the caddie form a duo having a long
relationship, so that the caddie becomes eventually almost
irreplaceable.
[0004] Most of the ordinary golf players cannot afford to use
caddie services and if they do, at least the benefit from knowing
the player's skills well enough is missed. Modern technology may be
utilized to overcome the obstacles and there have been some
attempts to do so. But due to only partial implementation the
overall effect has been quite the contrary. An extra device just
disturbs the player, it may provide inadequate information,
distracts the player's attention from the game and does not really
support in developing skills and achieving better results. These
particular issues are addressed by the system and method presented
in this application.
BRIEF SUMMARY OF THE INVENTION
[0005] The object of the present invention is to provide a golf
swing detection system, a golf swing detection device and a
computer program utilized in the golf swing detection system.
[0006] The objects of the present invention are fulfilled by
providing a golf swing detection system comprising: [0007] a swing
detection device configured to be attached to a golf player's
forearm, the detection device comprising: [0008] a battery; [0009]
a power/energy management circuit; [0010] a tag reader; [0011] a
motion sensor; [0012] a processor unit comprising a memory unit
including a computer program; [0013] the memory unit and the
computer program configured to, with the processor unit, cause the
swing detection device at least to process motion sensor data and;
[0014] a wireless transceiver; and [0015] a mobile device
comprising computer program to process motion data received from
the swing detection device,
[0016] characterized in that the ball hit recognition process
comprises at least one detection stage in the swing detection
device or in the mobile device (6) where a particular detection
stage comprises a particular gesture recognizer accomplished by
program modules that are configured to recognize particular golf
swing sub-gestures or a collision event between a golf club and a
golf ball.
[0017] Also the objects of the present invention are fulfilled by
providing a golf swing detection device comprising: [0018] a
battery; [0019] a power/energy management circuit; [0020] a club
identification reader; [0021] a wireless transceiver; [0022] a
motion sensor; [0023] a processor unit comprising a memory unit
including a computer program module; [0024] the memory unit and the
computer program module configured to, with the processor unit,
cause the swing detection device at least to process motion sensor
data,
[0025] characterized in that a golf ball hit recognition process
comprises at least one detection stage in the swing detection
device and that a first detection stage comprises a particular
gesture recognizer accomplished by program modules that are
configured to recognize at least a first golf swing sub-gesture and
a second golf swing sub-gesture.
[0026] Also the objects of the present invention are fulfilled by
providing a computer program comprising at least one of the
following computer program modules: [0027] a first computer program
module including computer readable code for detecting a stillness
sub-gesture preceding swing sub-gestures; [0028] a second computer
program module including computer readable code for detecting a
collision event of the golf club with a golf ball; [0029] a third
computer program module including computer readable code for
detecting swing sub-gestures including a backswing sub-gesture, a
downswing sub-gesture, a collision event, and a follow through
sub-gesture.
[0030] Some advantageous embodiments of the invention are disclosed
in the dependent claims.
[0031] Further scope of applicability of the present invention will
become apparent from the detailed description given hereafter.
However, it should be understood that the detailed description and
specific examples, while indicating preferred embodiments of the
invention, are given by way of illustration only, since various
changes and modifications within the spirit and scope of the
invention will become apparent to those skilled in the art from
this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The present invention will become more fully understood from
the detailed description given herein below and accompanying
drawings which are given by way of illustration only, and thus are
not limitative of the present invention and wherein
[0033] FIG. 1 shows an exemplary representation of an electronic
caddie arrangement where the golf swing detection device according
to the invention is utilized;
[0034] FIG. 2 shows an example where a golfer identifies a golf
club with the golf swing detecting device according to the
invention;
[0035] FIG. 3 shows an example where a golfer wearing the golf
swing detecting device according to the invention is concentrating
on a stroke (in a stillness sub-gesture);
[0036] FIG. 4 shows an example of a trajectory of the golf club
head during a golfer performing an example of a typical full
swing;
[0037] FIG. 5 shows an example of a trajectory of a detection
device during a full swing;
[0038] FIG. 6A shows an example of an acceleration signal captured
with a detection device during a full swing with a driver;
[0039] FIG. 6B shows an example of an acceleration signal when it
is divided into separate swing phases according to the
invention;
[0040] FIG. 7A shows main electrical components of the swing
detection device according to the invention;
[0041] FIG. 7B shows an exemplary layer diagram of the division of
the recognition algorithm according to the invention between the
processing units of the swing detection device and a mobile
device;
[0042] FIG. 8 shows as a flow chart an example of a stillness
recognizing procedure in the swing detection system according to
the invention;
[0043] FIG. 9 shows as a flow chart an example of a hit recognizing
procedure in the swing detection system according to the
invention;
[0044] FIG.10 shows as a flow chart an example of a peak
recognizing procedure in the swing detection system according to
the invention, and;
[0045] FIG.11 shows as a flow chart an exemplary overview of a
complex recognizing procedure in a system according to the
invention
DETAILED DESCRIPTION OF THE INVENTION
[0046] In the following description, considered embodiments are
merely exemplary, and one skilled in the art may find other ways to
implement the invention. Although the specification may refer to
"an", "one" or "some" embodiment(s) in several locations, this does
not necessarily mean that each such reference is made to the same
embodiment(s), or that the feature only applies to a single
embodiment or all embodiments. Single feature of different
embodiments may also be combined to provide other embodiments.
[0047] An exemplary embodiment of an advanced electronic caddie
system, CaddieON.TM., is shown in FIG. 1. The electronic caddie
system comprises golf club identifier tags (reference 3 in FIG. 2)
on the golf clubs, advantageously a wrist-borne golf swing
detection device 2, a mobile device 6 (for example a smartphone)
and a backend server 4. The golf club identifier tags 3, the golf
swing detection device 2, the mobile device 6, and the backend
server 4 are connected together wirelessly; references w4, w2, and
w3 in FIG. 1.
[0048] The player installs the computer program accomplishing the
procedure according to the invention on his or her mobile device 6
and marks his or her golf set with the club identifier tags 3. The
mobile device 6 may be for example a smartphone, a tablet or a
laptop. The golfer has activated a wireless connection between the
swing detection device 2 and the mobile device 6, reference w4. The
golfer wears the swing detection device 2 on his or her wrist or
forearm during the game. The swing detection device 2 reads the
club information from the tag 3 before a stroke is taken, records
the stroke and transfers data to the mobile device 6. The mobile
device 6 advantageously combines stroke data with the available
location information, for example satellite 7 based location
information (GPS, Glonass, etc.) (reference w1).
[0049] By utilizing the swing detection device 2 according to the
invention the golfer can focus on his or her game to the maximum.
The mobile device 6 keeps track of all the strokes that the swing
detection device 2 has indicated during the game. Advantageously it
offers a review and manual editing options for the player as well.
Game data 8 is stored to and made available 4a simultaneously on
the backend server 4, reference w2. The player can choose to get
quick feedback about the status of his or her game on the display
of the mobile device 6 at any time during the round through
application views such as scorecard, rangefinder or course map.
Advantageously also other relevant information is available, for
example a ball lie can be recorded and information about weather
conditions is available. This adds value to analysing the round and
thus improving the skills more comprehensively.
[0050] The electronic caddie system can also suggest suitable game
strategy like a stroke plan and clubs based on the golfer's former
statistics and course information available online from the backend
server 4. The backend server 4 offers a personal portal for
accessing and analysing the game afterwards. There can be a
separate portal for golf instructors so they can get more detailed
information about their group. The server collects also versatile
course and game data for the golf course operators 9 to improve the
playing experience and thus the attractiveness of the course.
[0051] There are thirteen clubs and a putter in a typical golf bag.
The player attaches a tag 3 to each of the clubs so that the clubs
can be identified when a stroke is about to be taken. Tags 3 can
advantageously be based on any wireless technology like RFID (Radio
Frequency IDentification) or NFC (Near Field Communication). The
tag may also be an entity including optically readable code that
can be attached to the golf club. An individual code, club ID, is
written to the tags 3 when it is manufactured. The swing detection
device 2 includes advantageously an integrated reader antenna that
is brought to a close proximity of tag 3 so that tag ID can be read
either wirelessly or optically. An advantageous position of the tag
3 is on the grip or at the end of the club or on the shaft. That
way the reading experience of the club ID from the tag 3 is most
convenient. Antenna of the swing detection device 2 is designed so
that reading performance is optimal for the tag 3. In one
advantageous embodiment the antenna is embedded into the wrist band
of the swing detection device 2.
[0052] A 3-axis accelerometer records swing and stroke related data
enabling reliable detection of the very moment when the club hits
the ball. The hit detection algorithm according to the invention
runs advantageously on the microprocessor in the swing detection
device 2 or alternatively in the mobile device 6. Naturally, the
algorithm can also be partitioned between the existing processors
as seen feasible in the chosen embodiment. The complete algorithm
comprises several algorithms in which sub-gestures characteristic
to a particular stroke gesture or event are utilized. In this
context a gesture means a physical movement of the golfer that is
visible to the human eye. A sub-gesture is a part of a longer,
continuous gesture made by the golfer. One part of the algorithm
according to the invention is simple enough to be implemented for
example with a state machine that can be found in the prior art
accelerometers.
[0053] Different hardware (for example field-programmable gate
array (FPGA)) and software implementations for all algorithms
according to the invention are possible. The swing detection
procedure according to the invention provides improved power
efficiency that means a longer overall usage time. The swing
detection system according to the invention allows utilizing
multiple algorithms for different types of strokes and clubs. The
algorithms can be executed simultaneously in different entities of
the electronic caddie system or one at the time. Club ID or golfer
position on the golf course can advantageously be used as a
parameter for selecting the best detection algorithm. One may also
choose to apply auto-adaptive algorithms in the future so that
player specific gestures are recognized better.
[0054] One part of the personal electronic caddie system according
to the invention is an application that runs on the mobile device
6. It can be used as a stand-alone golf application but
advantageously it may be used in conjunction with a backend server
4 (reference w2). The mobile device 6 can be based on any platform
providing needed software tools for 3.sup.rd party developers,
methods for installation of downloadable application, access to
satellite 7 positioning, (for example GPS or Glonass, reference
w1), and wireless data connectivity sub-systems (for example
Bluetooth, WLAN or a cellular connection, references w2 and w4).
Some smartphone platforms of this kind are for example Android, iOS
and Windows Phone, but there are proprietary platforms to which the
electronic caddie system according to the invention can be
implemented.
[0055] The swing detection application implements a user interface
having several informative display views to be utilized during a
round of golf. The main ones are as follows.
[0056] The main view is utilized for making golfer and game related
basic settings, selections and preferences. The golfer can
advantageously use the view to choose to enter player data; basic
application settings; swing detection device 2 and club 5 set
settings; selection of course to be played; and to start the game.
Extra information of the local weather, golf course operators'
events etc. can be offered to the players through news feed.
[0057] The score card view is an electronic version of golf score
card indicating basic data of on-going game such as the number of
the played hole, its par value and number of strokes the player has
taken. Score card data is based on individual course data that is
collected automatically and confirmed by the golfer. The score card
is transferred to the player portal on the backend server 4 after
the hole has been played or the round completed. Besides by the
player himself, the results could be utilized by different golf
information systems for example for tournaments, competitions and
calculating handicaps.
[0058] The course strokes view presents stroke information for an
individual hole as a chronological list, i.e. a stroke number, club
used, ball lie, and distance per stroke. Data collection is
automated by the electronic caddie system according to the
invention but before storing the data a golfer reviews and confirms
the list. To add penalty strokes or, in a case where there are
errors in the collected data, an option to edit each line as well
as delete and add strokes are advantageously offered. The final
list is utilized by the score card view and synched to the backend
server 4.
[0059] The range finder view is a summary presentation showing
distances to points of interest on the current course. Specifically
the distance from the golfer to the hole and known hazards are
calculated based on the measured location and the electronic map
information. This information helps planning the remaining strokes
and selection of the suitable clubs. The location is measured with
the positioning sub-system on mobile device 6 and information about
hazards is fetched from the course database on the backend server
4.
[0060] The map view is a graphical map view of the golf course. It
combines relevant parts of the course review and the range finder
views with free online map data such as Google Earth. Positions of
each taken stroke, the current position of the ball, the game plan
to the green, the position of the hole and locations of hazards are
overlaid on the map. On golfer's choice also stroke positions and
their end results from the previous rounds can advantageously be
overlaid on the map by making a simple database query. An actual
distance of taken strokes and a distance of the planned strokes and
from the ball to the hazards can be shown. A projected ball landing
area for planned strokes can be calculated and made visual on the
map. They are based on the golfer's history data of the stroke
accuracy.
[0061] Planned strokes can advantageously be edited on a touch
screen of the mobile device 6. Also a suggested club for the next
stroke or other relevant information may be shown. The map can be
zoomed and panned on the touch display with fingers or
automatically when the game proceeds and the player is for example
approaching the green and requires a more detailed view. Measuring
a distance between arbitrary points of interest is also possible.
Also the position of other players using the electronic caddie
system according to the invention can be overlaid on the map. In
that way it is possible to warn a player from taking a shot if
other groups are within the reach of the striking distance of the
player. This feature improves the safety on the golf course
especially when the player has no visibility to the projected ball
landing area.
[0062] The electronic caddie system according to the invention also
offers many other possibilities to provide useful information to
the player. Highlights after the game (the best/longest strokes for
example), notification of other players' performance after storing
the score card and a history view (for example a summary of the
player's previous scores on the current course), to mention a
few.
[0063] According to the invention, the electronic caddie system is
also able to detect the ball lie automatically. Different surfaces
on each hole of the golf course (i.e. tee boxes, fairways, greens,
sand hazards) are mapped defining a set of coordinate points from
the boundary of each object. The coordinates may form a polygon and
each polygon is advantageously identified for a type of surface
they represent. The coordinate set of each object (or polygon) is
uploaded to the application before the golfer starts to play. When
the swing detection device 2 detects a stroke, it sends the
information to the mobile device 6. The golfer's coordinates given
by the GPS receiver of the mobile device 6 are checked against the
coordinate data of the polygons. When the golfer's coordinates fall
inside a defined polygon, the type of surface of the polygon is
given to the stroke. These method steps can advantageously be
implemented on the mobile device 6 or on the backend server 4.
[0064] The backend systems of the electronic caddie system
according to the invention comprise advantageously the following
main parts: a web server 4 and a database connected to it, portals
for players and the golf course operator 9, and communication
interface.
[0065] Users can access the web server 4 at any time with a browser
running on the mobile device 6 or on a personal computer. They are
for example able to study information about golf course operators
9, available courses and personal game history before the game. The
electronic caddie system application utilizes a specific
application programming interface (API) to communicate with the
backend server 4.
[0066] The database contains information about the registered
golfers and golf course operators 9. The information, reference 8,
may also comprise player profiles, score cards and detailed game
history, contact information of golf course operators and course
details (number of holes, course rating, scorecard, flag position,
etc.). Also player and game related information may be collected
and uploaded online during the game by the mobile device 6.
Information related to the golf course operator 9 is maintained by
a service provider.
[0067] The backend server 4 advantageously analyses the stored data
and provides versatile statistic and graphic views for players and
golf course operators 9 (reference 8a) through dedicated portals.
Scheduled calculation routines calculate aggregated statistics for
various sizes of geographical areas or entities (i.e. global,
country, and golf course specific) from all played golf rounds of
all players.
[0068] The player portal shows measures and development of golfer's
own game. It also gives possibilities to share information about
played games in social media or directly to other registered users
and portal visitors 10 (reference 8b). Individual golfers can
compare their statistics with other golfers according to different
geographical areas or entities like global, country, or golf
course. The golfer can also compare his or her statistics with the
average values of all golfers in different categories, based on the
total number of strokes. For example, a golfer can choose to
compare his or her statistics against the average of all golfers,
whose round score is between 11 and 20 strokes over par or with
golfers whose score is between 21 and 30, and so on. Moreover, the
system enables handicap calculation and statistics down to
individual club.
[0069] The golf course portal is the view for the operator 9. It
shows current positions of all players using the electronic caddie
system according to the invention. History data shows how the
course has been played: the route players have taken on the course,
where they have stroke the ball from. This information can be used
to proactively identify wearing on the course or monitor round
durations. Aggregated data from the golfers can be provided back to
them through course specific web pages showing for example an
average playing time on the course, the difficulty of each hole,
daily highlights from the field, etc. These types of views can be
easily generated on need basis.
[0070] Communication between the electronic caddie application in
the mobile device 6 and the backend server 4 is advantageously done
through representational state transfer (REST) API, which has the
following functions: uploading game results (scorecards), searching
golf courses and downloading course information, and logging a
player position during a game. Actions can be initiated from the
mobile device 6 side against the backend server 4 or alternatively
two-way messaging via mobile push notifications can be used.
[0071] FIG. 2 shows an exemplary situation where a golfer 1
identifies wirelessly a golf club 5 by his or her swing detection
device 2 before a stroke. Each golf club includes an individual tag
3 that is connected to a golf club 5. Advantageously the tag 3 is
fastened to the grip end of the club 5. Reference 5a depicts the
head of the golf club. When the swing detection device 2 has read
the tag 3 of the present club, it advantageously transmits club
identification information wirelessly to the mobile device 6 of the
golfer 1 (reference w4).
[0072] FIG. 3 shows an exemplary golfer 1 wearing a wristband type
swing detection device 2 that contains a motion sensor 22, for
example an accelerometer. As can be seen in FIG. 3, the swing
detection device 2 will be near the grip of the golf club 5 during
a golf stroke. In FIG. 3 the golfer 1 is concentrating the head of
the golf club beside the golf ball 31 before a stroke attempt. This
concentration phase is hereafter called as a stillness sub-gesture
30.
[0073] FIG. 4 shows a golfer 1 performing a full swing (full wave)
with a driver club as an example of a typical golf swing. Let us
consider a trajectory that the golf club's head 5a moves during the
swing gesture. Said trajectory is typically divided advantageously
into several sub-gestures. In this context a phase advantageously
depicts an electric signal representing a sub-gesture and an event
depicts a short incident during a gesture, for example a hit.
[0074] After `stillness` 30 follows a `backswing` 40 that is a
sub-gesture where the golfer 1 brings the club head 5a back and up.
The next sub-gesture is `downswing` 41 where the golfer brings the
club head 5a rapidly down to the ball. `The collision` 42 is an
event where the club head 5a collides with the golf ball. This may
also be called as `a hit sub-gesture` later on. The golf stroke
ends up to `a follow through` 43 sub-gesture where the golfer 1
brings the club head 5a forward and then to the pelvis level. While
different kinds of clubs and swing types exist in the golf game, it
is notable that all swings contain these same logical
sub-gestures.
[0075] In order to detect said sequence of sub-gestures or motions,
the swing detection device 2 with a motion sensor 22 can be
attached either to the golf club 5 or to the golfer's hand. From a
detection point of view an advantageous position for the motion
sensor 22 would be inside the head 5a of the golf club 5. A more
feasible approach may be to firmly attach a separate detection
device to the shaft of the golf club. However, from the golfer's
point of view the most practical and economical solution is to use
a single swing detection device that can be attached to the
golfer's wrist for the duration of a golf game.
[0076] In FIG. 5 is shown an exemplary trajectory depicting
movements of the swing detection device 2 during a full swing. The
motion starts with a `backswing` sub-gesture 50 where the hand of
the golfer 1 moves back and up. A `downswing` 51 sub-gesture
follows the `back swing` sub-gesture. In the `down swing`
sub-gesture 51 the hand moves rapidly down and forward drawing a
half circle in the air. After the collision 42 with the ball 31 the
stroke ends up to a `follow through` 53 sub-gesture where the hand
of the golfer 1 moves forward and up almost completing a
circle.
[0077] In a case where the head of the club 5a collides with the
ball during the swing the forces due to the collision with the ball
make the club 5 to vibrate. This vibration travels through the
shaft of the club 5 all the way to the golfer's hand and to the
swing detection device 2.
[0078] Series of motions of the hand clearly resemble the motions
of a golf club's head as shown in FIG. 4. However, there are the
following exceptions. An overall scale of the trajectory of the
swing detection device 2 is smaller than the trajectory of the golf
club head 5a. Therefore, also the speed of change and magnitude of
the acceleration are smaller. Also the trajectory in the transition
phase from `backswing` to `downswing` is simpler and shorter. The
collision with the ball is experienced only indirectly via the golf
club shaft and the golfer's hand. Also the trajectory in the
`follow through` sub-gesture is shorter. These exceptions
complicate making a reliable decision when a stroke has been
detected.
[0079] FIG. 6A shows an example of an acceleration signal 60
captured with the swing detection device 2 according to the
invention during a full swing with a driver club. The signal is an
example of a typical acceleration signal in the golf game. The
signal is captured with a 3-axis accelerometer sensor. For the sake
of clarity only one axis is visualized in FIG. 6A. The acceleration
sensor was firmly installed into a wrist-band type swing detection
device 2. The swing detection device 2 was attached to the golfer's
top hand holding the golf club 5.
[0080] The signal graph shows that an accelerometer 22 attached to
the golfer's wrist can be used for producing a meaningful input
signal for a golf swing recognizer algorithm because the signal 60
clearly responds to hand motions during a swing. When the amplitude
62 of the detected signal 60 changes, it reveals the collision 42
between the club head 5a and the golf ball 31. The collision can be
seen as multiple sharp, high amplitude spikes 64. It is noteworthy
that this oscillation due to collision is yet easily
distinguishable despite of an indirect measurement via the club
shaft, grip, glove, golfer's hand and the swing detection device
body 2.
[0081] FIG. 6B shows as an example the acceleration signal 60 of
FIG. 6A when the signal 60 is divided according to the invention to
four main phases of a golf swing. The main phases are `stillness`
610, `swing` 620, `hit` or `miss` 640, and `follow through`
660.
[0082] During `stillness` 610 the golfer concentrates. He or she
stands straight holding the club 5 with both hands so that the club
head 5a nearly touches the ball on the ground. As the golfer tries
not to move, the measured acceleration signal is typically very
steady for a while and hence this phase is called `stillness`.
[0083] During `swing` 620 the golfer slowly raises the club head
(`backswing`) and then rapidly swings it towards the ball
(`downswing`). The measured acceleration signal 60 contains first a
gentle ramp to one direction (due to `backswing`) and then a
steeper ramp to the opposite direction (due to `downswing`).
Naturally the direction depends on the accelerometer polarity.
[0084] During `hit` 640 (i.e. collision) the collision between the
club head 5a and the golf ball 31 makes the club 5 to vibrate for a
short period of time. This vibration travels via the club shaft to
the golfer's hand and to the swing detection device 2. The `hit`
generates multiple declining sharp peaks of opposite directions in
the acceleration signal. In the case of `miss`, this oscillating
pattern is not present in the acceleration signal 60. During
`follow through` phase 660 the golfer gently decelerates the motion
of the club while the club head continues to follow its trajectory
and finally returns the club to the initial position. The measured
acceleration signal 60 contains a gentle ramp to one direction and
after a moment another gentle ramp to the opposite direction.
[0085] According to the invention, the phases of the golf swing
(i.e. `backswing`, `downswing`, `collision`, `follow through`) and
related sensor signal parts ('stillness', `swing`, `hit` or `miss`,
and `follow through`) are essential to such golf swing recognition
algorithm. Therefore, the golf swing recognition algorithm
according to the invention is based on phases depicted in FIG. 6B.
The purpose of the golf swing algorithm according to the invention
is to detect and notify when a golfer hits a ball. Therefore, the
primary requirements for such algorithm include capability to
detect a golf swing from other motions and when recognizing said
golf swing, capability reliably to separate between `hit` and
`miss`.
[0086] Secondary requirements may be a reasonably fast response
time to notify about a `hit` soon after swing gesture. Also low
power consumption makes possible a mobile, battery powered swing
detection device that has a long operating time. Also efficiency in
terms of processing power and memory consumption facilitates a
commercially feasible consumer class product.
[0087] When a captured acceleration sensor signal 60 is fed into
the algorithm according to the invention, it will output a result
that is either positive (i.e. `hit`) or negative (i.e. `miss`). In
the case of a positive output the algorithm brings out that the
acceleration signal 60 contains a golf swing with a ball hit. In
the case of a negative output the algorithm brings out that the
acceleration signal 60 does not contain a golf swing at all or that
the player missed the ball.
[0088] An output of a stroke detection algorithm can be correct or
incorrect depending on the algorithm's capability to accurately
classify different kinds of signals. By giving a label `true` to
depict correct output and `false` to depict incorrect output the
algorithm's outputs can be further classified to four groups based
on their correctness. The output can be true positives (TP), false
positives (FP), true negatives (TN), and false negatives (FN). An
ideal recognition algorithm outputs only true positives and true
negatives. Detection algorithms known in the art more or less
frequently fail in this classification and output also false
positives and false negatives.
[0089] The definition given above contains dualities. For each
appearance of a false negative detection there will be one true
positive detection that is missing. Both illustrate an error where
the utilized detection algorithm failed to recognize a golf swing
with a ball hit. Likewise, for each appearance of a false positive
detection there will be a true negative detection that is missing.
Both illustrate an error where the utilized detection algorithm
notified about recognition of a hit when the signal actually did
not contain a golf swing with a ball hit. Hence, if the test
signals are known, the performance of the detection algorithm in
terms of a correct classification of input signals can be fully
understood with using either the terms true positive (TP) and false
positive (NP) or true negative (TN) and false negative (FN).
[0090] During a game of golf most of the playing time is spent in
activities other than hitting the ball such as moving to a new
location, waiting for own turn, or practicing swings without
hitting a ball. As a consequence, negative output from the
detection algorithm is far more expected than a positive output.
This makes the positive outputs more interesting and convenient to
focus on in analysing the detection in the algorithm. In the
following description true positives (TP) and false positives (FP)
are used in the description to depict detection algorithm's
decision making capability instead of their negative
counterparts.
[0091] Any recognition or detection algorithm tries to maximize the
amount of true positives and minimize the amount of false
positives. A common consequence of an attempt to increase the
classification accuracy of the recognition algorithm is that the
recognition algorithm becomes more complex. This added complexity
usually means spending more CPU cycles and memory and hence also
more power, which is a limited reserve in a battery-powered mobile
device.
[0092] According to the invention power can be saved remarkably by
dividing the recognition algorithm into multiple stages where each
stage has its own computer program module. In an exemplary case an
acceleration signal of a golf swing may contain a ball hit. The
original, complete signal is advantageously given to the lowest
stage for execution. The lowest stage has the least accurate
recognition algorithm but also the lowest power consumption. In a
case where the recognition algorithm generates a positive output
from the complete signal relevant parts of the complete signal are
propagated for examination to the next higher stage that includes a
more capable recognition algorithm. The highest stage with the most
accurate recognition algorithm (with also the highest power
consumption) makes the final decision about the `hit` or `miss`.
The decision can take place only if the complete signal reaches the
highest stage of the recognition algorithm. However, a negative
decision can be made already before that. With the recognition
algorithm according to the invention high momentary power
consumption is minimized by limiting running time.
[0093] By utilizing the recognition algorithm according to the
invention most power consuming components can be kept in sleep mode
most of the time. However, a full processing capacity is available
when needed. Therefore, maximum recognition accuracy can be
achieved. A basic rule of the recognition algorithm according to
the invention is that any stage of the recognition algorithm must
not reject any true positive indication. However, any single stage
does not need to reject all false positives but any source for
false positives should be blocked by at least one stage of the
recognition algorithm. In the recognition algorithm according to
the invention all true positives (TP) pass all stages and all false
positives (FP) get blocked at some stage of the recognition
algorithm according to the invention.
[0094] FIG. 7A shows, by way of example, main functional parts of
the swing detection device 2 according to the invention. The swing
detection device 2 advantageously comprise a microprocessor unit 20
(MPU) with a memory unit 24 (RAM/ROM), an RFID reader 23 with an
integrated antenna, a motion sensor, for example a 3-axis
accelerometer 22 (ACC), a gyroscope, or a magnetometer, a Bluetooth
connectivity module 28 (BT), a led (LED) 25 and a vibrator (VIBRA)
26 for user feedback. The swing detection device 2 comprises also a
battery 29 and a power/energy management circuit 21 (EM/PM).
[0095] The swing detection device 2 may be connected to the mobile
device 6 via a wireless connectivity link w4 such as Bluetooth. The
link is mainly used for transferring raw or processed acceleration
data of the stroke events, parameters and control messages.
Communication periods are advantageously optimized in order to
achieve better power efficiency and longer operation times. Other
functionalities like updating the firmware of the swing detection
device 2 over-the-air are also possible.
[0096] The vibrator 26 and led 25 are used for giving necessary
indications and feedback to the golfer. Golfer disturbance should
be minimized in all cases. Blinking and different colours of the
led 25 are used for informing about the modes of the swing
detection device 2 (i.e. power on indication, battery status and
charging state) as well as possible fault situations. The vibrator
26 can advantageously be used for giving discreet notes of some key
events such as successful tag reading, `hit` detection and if the
mobile device needs attention. The golfers can advantageously also
opt for not using the vibrator 26 by configuration options.
[0097] The accelerometer 22 may be utilized also for detecting some
simple user commands. A user command may be defined for example by
a number of taps or any other detectable gesture like hand shaking.
A double tap may advantageously mean `end of course` and hand
shaking `start of course`, for example. The exact meaning is
implementation dependent.
[0098] FIG. 7B shows an example how the recognition algorithm may
be divided into computer program modules between the swing
detection device 2 and mobile device 6. A natural extension to the
previous is that different recognition algorithm stages do not need
to be run on the same physical component inside the swing detection
device 2. On the contrary, dividing recognition algorithm stages
according to the invention to different processing units a
remarkable power saving is acquired as a technical effect.
[0099] FIG. 7B shows an example of an algorithm division into
multiple processing units in a caddie system according to the
invention. The swing detection device 2 is a physical entity that
contains the motion sensor 22, for example an accelerometer, and
hence must be attached to the golfer's hand or the golf club in
order to capture the motions. The accelerometer component 22 may
comprise a programmable logic and therefore it can advantageously
execute the first stage of the algorithm 220 (i.e. a first program
module) while the rest of the caddie system is in sleep mode. A
positive recognition from the first stage of the recognition
algorithm wakes up the microprocessor unit 20 (MPU) with an
interrupt.
[0100] Thereafter streaming raw accelerometer signal to the MPU 20
begins after updating the accelerometer settings to this new
operation mode. The second stage of the recognition algorithm 240
(i.e. a second program module) now runs on the MPU 20 of the swing
detection device 2. A positive recognition from the second stage of
the recognition algorithm triggers advantageously a wireless
communication with an external mobile device 6.
[0101] After this relevant parts of the raw accelerometer signal
are then streamed to mobile device's CPU 60 after updating the
accelerometer settings. The third stage of the recognition
algorithm 600 (i.e. a third program module) now runs on the
powerful central processing unit 60 (CPU) of the mobile device 6.
If necessary, more stages may be added, for example wireless
communication to a backend service that is running on a remote
backend server cluster 4 (not illustrated in FIG. 7B). After the
last stage of the recognition algorithm according to the invention
the signal for the final output of the algorithm is given (i.e. `a
hit`).
[0102] The above-depicted division of the algorithm into multiple
hosts provides another remarkable technical effect. The MPU 20 of
the swing detection device 2 can be a light-weight component
because it does not need to perform complex analysis on the
acceleration signals in real time. Instead, the MPU 20 of the swing
detection device 2 can advantageously send a signal capture
containing potential data for a hit recognition to the mobile
device 6 for a more complex analysis. After that the MPU 20 can
continue to execute a less complex second stage of the recognition
algorithm for finding another potential signal. Hence, the
recognition algorithm division into multiple hosts according to the
invention also provides the technical effect of running different
recognition algorithm stages in parallel, which in turn allows one
or more stages to process the signal non-real time and thus even
more complex signal analysis.
[0103] It is obvious to a person skilled in the art that also other
kinds of divisions are possible. The decision about the needed
recognition algorithm stages depends for example on a system
architecture, communication bandwidth and cost, as well as
capabilities of the available hardware components. For example, if
enough bandwidth is available from the swing detection device 2 to
remote server cluster 4, then in that case all processing could be
performed in the cloud. It is also possible that an accelerometer
sensor 22 may contain enough processing power to process the
complete stillness, swing and hit detection recognition algorithm
alone.
[0104] FIG. 8 shows an example of a stillness sub-gesture 30
recognizing procedure utilized in the algorithm according to the
invention. The purpose of this stage of the recognition algorithm
is to recognize the moment when the golfer concentrates on the
upcoming swing. In this context some parts of the algorithm
according to the invention may be called as a recognizer. A
recognizer is a particular algorithm module configured to detect a
particular swing sub-gesture or collision event. It may be hardware
or a software based solution or a combination of them.
[0105] The stillness recognizer is best suited for the first stage
of the recognition algorithm 220 because it is simple enough to be
executed on the accelerometer's 22 logic part. Moreover, it removes
the need to buffer data on the accelerometer 22 as all the other
interesting signal parts come after it. This stage of the
recognition procedure may advantageously be accomplished by a first
program module executed in the accelerometer 22. The first program
module may advantageously be implemented as a FPGA hardware
implementation.
[0106] The features to be observed from the acceleration signal
include detection of an orientation and stillness of the swing
detection device 2, which can be observed either in parallel or in
sequence. FIG. 8 shows an example of the latter where a state
machine re-evaluates each acceleration signal sample. The procedure
begins from start state 80 where variables are initialized. An
orientation check state 81 determines the orientation of the swing
detection device 2 from one or more samples, for example by
comparing the three signals from the 3-axis accelerometer 22 to
pre-defined threshold levels. If the swing detection device 2 is
held still as assumed, only 1 g acceleration due to gravity is
present. When the detected gravity vector is divided into three
orthogonal signals, the current orientation of the accelerometer 22
can be detected.
[0107] Next, in state 82 a decision is made based on the
orientation. The procedure will proceed to the next state 83 only
if orientation resembles the golfer's posture in the concentration
phase before a swing.
[0108] `Stillness` is then detected in a separate state 83, for
example by requiring that the first difference of the vector form
of the acceleration signal stays between two thresholds for a
certain period of time. If this requirement holds long enough, then
after state 84 the procedure proceed to the next state 85.
[0109] At this state 85 the orientation is checked again and the
golfer's posture gets confirmed in state 86. In order to adapt to
different concentration times, `stillness` detection is performed
again in state 87, but this time the procedure waits until
stillness is over in state 88, i.e. until motion is detected. This
motion is assumed to be due to the golfer beginning the `backswing`
and hence the sleeping MPU 20 of the swing detection device 2 is
now woken up with an interrupt in state 89.
[0110] Following the acceleration signal time-wise, after the
stillness phase 610 comes the swing phase 620 and after that the
hit or miss phase 640. In golf there are multiple different types
of swings such as full swing, half swing, duff, pitch, and putt.
Moreover, a golfer's personal style and experience is most visible
in this phase 620. Hence, the recognition algorithm for swing phase
620 must tolerate much variation, which adds complexity to it.
[0111] On the other hand the next phase 640, `hit` or `miss`, is
much simpler to recognize partially due to very distinctive high
amplitude peaks, partially due to a fairly limited pass band for
frequencies that come from the club oscillation. Moreover, if a
potential hit is not present in the acceleration signal 60,
analysis can be stopped immediately and the more complex swing
analysis 620 can be skipped altogether. Therefore, the `hit` or
`miss` phase 640 is more suitable to be executed in the second
stage of the recognition algorithm 240 than the swing phase
620.
[0112] FIG. 9 shows an example of a hit recognizing procedure. The
MPU 20 of the swing detection device 2 has been woken up by an
interrupt signal 89 from the stillness recognition procedure. The
hit recognizing procedure is intended for the second stage of the
recognition algorithm 240 and aims to recognize the moment when the
club collides with the ball (i.e. impact). This stage of the
recognition procedure may advantageously be accomplished by a
second program module executed in the MPU 20 of the swing detection
device 2.
[0113] The hit sub-gesture recognizing procedure starts with
initialization state 90. Next, a new acceleration signal sample is
acquired from the accelerometer sensor 22, state 91. The
acceleration signal comprises values from the accelerometer's X, Y,
and Z axis. The sample is processed in state 92 with a bandpass
filter to attenuate all other than club oscillation frequencies.
Next, the three values representing the 3-axis of the accelerometer
22 are combined to form a vector representation of the acceleration
in state 93. The negative side of the acceleration signal is
advantageously reflected to the positive side (i.e. compose an
absolute value), state 94. The absolute value vector representation
is then low pass filtered to smoothen the signal, state 95. As a
result of these pre-processing steps, a ball hit appears as a
single peak on the positive side, which can be detected with a
fairly simple peak detector, state 96.
[0114] However, this recognition procedure may not distinguish for
example a club hitting a ball from tapping the detection device 2
with a finger. Hence, if a potential hit is found, state 97, the
mobile device 6 is notified, state 98, and relevant parts of the
acceleration signal 60 are transferred from a local buffer of the
swing detection device 2 to the mobile device 6 for further
analysis, i.e. to stage three of the recognition algorithm 600.
[0115] FIG. 10 shows an example of the peak recognizing procedure
that is executed in states 96 and 97 of FIG. 9. While the bandpass
and low pass filters can be implemented for example with a classic
FIR filter (Final Impulse Response), a peak detector design is not
so obvious. The peak recognizing procedure is a part of the second
stage of the algorithm 240 and it aims to recognize a peak that
passes a pre-defined threshold level. In addition, the peak length
is limited to minimum and maximum length.
[0116] The peak detection procedure starts with initialization,
state 100, and then keeps on reading in new samples until one that
passes a set threshold level is found, state 101. A potential peak
has now begun and a first timer is initialized for measuring peak
minimum duration, state 102. Samples are then compared against the
set threshold, state 103, to ensure that the peak does not end
prematurely before a minimum duration timer triggers in state
104.
[0117] If the found peak is long enough, state 104, a second timer
is initialized in state 105 for measuring maximum duration of the
detected peak. The second timer is advantageously not triggered in
state 106 before the signal drops below a predefined threshold
level, state 107.
[0118] When the signal has dropped below said threshold, a peak is
notified in state 108 (i.e. state 98 in FIG. 9).
[0119] FIG. 11 shows an overview of a recognition procedure based
on the last stage algorithm 600 that advantageously may be executed
in the CPU 60 of the mobile device 6. A moment of stillness (state
89 in FIG. 8) and a potential hit (state 98 in FIG. 9) have already
been detected by lower algorithm stages 220 and 240 that
advantageously have been executed in the accelerometer 22 and/or in
the MPU 20 of the swing detection device 2.
[0120] The `follow through` procedure will check from the buffered
signal parts whether or not enough relevant features for a `swing`,
`hit` and `follow through` are present. This procedure will output
the final decision of the swing detection system according to the
invention. This stage of the recognition procedure may
advantageously be accomplished by a third program module executed
in the CPU of the mobile device 6.
[0121] The last stage procedure starts from initialization, state
111, and proceeds to analyse `swing` features, state 112. In this
state 112 the procedure must take into account different kinds of
swing types in golf for example with multiple parameter sets. The
implementation is advantageously a state machine that tracks the
signal form with thresholds and timers.
[0122] Alternatively the implementation may be a tester for the
signal's rate of change such as a ramp detector. Or the
implementation may be based on cross-correlation with a known swing
signal coupled with a peak detector. Even a trained Hidden Markov
model (HMM) may be utilized as a gesture recognizer.
[0123] If a `swing` cannot be detected in state 113, the procedure
immediately outputs a negative decision, state 119.
[0124] If a `swing` is present in the signal, then a `follow
through` will be analysed, state 114, and tested, state 115, in a
similar manner using similar techniques as in state 112.
[0125] If a `follow through` cannot be detected, state 115, the
procedure immediately outputs a negative decision, state 119.
[0126] If decisions in states 113 and 115 are both positive, the
procedure moves to state 116.
[0127] At the end a more careful `hit` analysis will be performed
in state 116. In state 116 the goal is to reveal the signal pattern
due to oscillating club and distinguish it from other high
amplitude spikes such as tapping the detection device with a
finger, clapping hands together, turning the detection device very
rapidly or shaking the detection device.
[0128] There are at least three methods to reveal a `hit` in
decision making in state 117. In the first method an oscillation
pattern of the golf club is searched for. If it is found, a
positive result is outputted, state 118.
[0129] In a second possible method to reveal a `hit` all known
sources for false positive signals are rejected by explicitly
looking for their features from the signal (for example via
cross-correlation with a known bad signal). In that method a
negative result is outputted, state 119, if any of the false
positive signals are present.
[0130] In a third method a hybrid approach utilizing features of
both the above-mentioned methods may be utilized.
[0131] Naturally, a recognition algorithm may give more weight on
some features over the others, up to the point that some parts of
the signal (such as `swing` or `follow through`) may be omitted
completely. Especially, if a club type can be detected, an
algorithm tailored for the particular club type can be used. This
approach can assist in acquiring good detection accuracy when very
different kinds of swings need to be supported. For example the
recognition algorithm version for a driver club might be different
than the recognition algorithm version for a putter club as these
clubs are typically used for different kinds of swings.
[0132] Any of the recognition method steps or recognition procedure
phases or states described and illustrated in FIG. 8-11 may be
implemented by program modules including computer program
instructions that are executable in a general-purpose or
special-purpose processor and that are stored in a
computer-readable storage medium (for example a disk, memory or the
like). The program module may also be implemented by a FPGA
circuit. References to `computer-readable storage medium` and
`computer` should be understood to encompass specialized circuits
such as field-programmable gate arrays, application-specific
integrated circuits (ASICs), USB flash drives, signal processing
devices, and other devices.
[0133] Some advantageous embodiments according to the invention
were described above. The invention is not limited to the
embodiments described. The inventional idea can be applied in
numerous ways within the scope defined by the claims attached
hereto.
* * * * *