[0001] The present invention relates to a method and a system for detecting an offside situation
during a game of football (soccer).
[0002] In football usually at least two referee's (a referee and a linesman) are to referee
the play. An important rule to be observed and refereed is offside. Offside may occur
if a first player, usually an offensive player, of a first team is located between
the goalkeeper and all the other players of the second team. If another player of
the first team passes the ball to the first player at the moment that the first player
is between the goalkeeper and the other players, the first player is deemed to be
offside. The linesman is to detect such a situation and to raise the flag to indicate
to the referee that the first player is offside.
[0003] In order to determine whether the first player is offside, the linesman needs to
determine a position of the first player of the first team with respect to a position
of the players of the second team exactly at the moment when another player of the
first team kicks the ball towards the first player.
[0004] However, usually, the ball is not near the first player and therefore, the linesman
cannot see the first player and the ball at a single glance. Therefore, the linesman
commonly keeps the ball in sight and as soon as the ball is kicked, he changes his
sight towards the first player. Although the change of sight occurs in a very short
period, e.g. several milliseconds, the position of the first player and/or a number
of the players of the second team may have changed considerably. Further, other players
may obstruct the sight of the kick of the ball. Also, depending on the position of
the referee with respect to the first player of the first team and some of the players
of the second team, it may be that the linesman misjudges the relative position of
the players. As a consequence of the aforementioned reasons and possibly other reasons,
the linesman often misjudges and, when in doubt, calls for offside, although the first
player was actually not offside.
[0005] It is an object of the present invention to provide a method and system for assisting
the referee and linesman in correctly judging offside.
[0006] The object is achieved in a method for detecting an offside situation during a soccer
game. The method comprises generating a detection signal when a ball is kicked by
a first player and supplying the detection signal to a signaling system. The signaling
system generates an observable signal to be observed by a referee, in response to
receipt of the detection signal.
[0007] The above method allows the referee to detect a position of a second player at the
moment of observation of the observable signal. As used herein, a referee may be the
actual referee or may be a linesman or may be any other person observing the game.
[0008] As a detection signal is generated and converted to an observable signal, the referee
may keep primarily a possibly offside player in sight, instead of the ball. There
is no need for the referee to observe the (kick of the) ball. As used herein, the
term 'kick of the ball' is intended to refer to any kind of contact with the ball
by a player that may or will lead to offside. At the moment that a player kicks the
ball, the observable signal is generated. When perceiving the observable signal, the
referee keeping the possibly offside player in sight can immediately determine whether
the player is at that moment, i.e. the moment of the kick of the ball, actually offside.
[0009] In an embodiment a further referee may observe the ball and, using a suitable system,
the further referee may activate a detection signal generator, e.g. by pushing a button,
for generating the detection signal.
[0010] In an advantageous embodiment of the method, the method further comprises sensing
a sound signal produced by the ball; processing the sound signal in order to determine
whether the ball is kicked; and if it is determined that the ball is kicked, generating
the detection signal. When a player kicks the ball, a sound vibration is generated
in the ball. The sound vibration may be sensed. However, also other events may generate
a sound vibration in the ball. Therefore, any sensed sound signal is processed, e.g.
a comparison with a predetermined sound signal of a kick of the ball or spectral analysis.
Then, if it is determined that a sensed sound is the sound of a kick of the ball,
the detection signal is generated. Thus, the moment of determination of kicking the
ball is not dependent on the subjective observation of a person, but is objectively
determined by electronic means.
[0011] In an embodiment of the method generating a detection signal comprises compiling
the detection signal, a content of the detection signal comprising at least one element
of the group comprising detected sound information data and a ball identification
code. Thus, the detection signal may be compiled from a number of kinds of information.
For example, if a number of balls may be used, each ball may comprise its own identification
number in order to prevent that a false or erroneous observable signal is generated
as a consequence of a detection signal generated in another ball. The detected sound
information may be used to control a level of the observable signal thereby providing
information to the referee how hard the ball was kicked. If only a soft kick was given,
the referee may determine that the ball was not intended to be kicked towards the
possibly offside player presuming that the distance between the ball and the offside
player is large.
[0012] In an embodiment of the method the detection signal is generated in the ball. In
this embodiment, the method comprises wirelessly transmitting the detection signal
from the ball to the signaling system.
[0013] In an embodiment of the method the observable signal comprises a signal selected
from the group comprising an audible signal, a visual signal, and a tangible signal.
A sound signal may be provided to the referee. Likewise, a light signal may be provided.
Further, likewise, a tangible signal may be provided to the referee. In an embodiment
two or more of these signals are provided to the referee.
[0014] In an embodiment, wherein the observable signal comprises a tangible signal, the
step of generating an observable signal comprises generating a vibration in an object
to be held by the referee, the object in particular being a flag handle. Also other
signal generators may be arranged in the flag handle, such as an audible signal generator
and/or a visible signal generator.
[0015] The present invention further provides a system for performing the method. The system
for detecting an offside situation during a soccer game comprises a detection signal
generator for generating a detection signal when a ball is kicked by a player; a detection
signal transmission system for supplying the detection signal from the detection signal
generator to a signaling system; and an observable signal generator comprised in the
signaling system for generating, in response to receipt of the detection signal, an
observable signal to be observed by a referee.
[0016] In an embodiment, the detection signal generator is arranged in the ball.
[0017] In an embodiment the detection signal generator comprises a sound sensing means,
in particular a microphone; and a sound processing means coupled to the sound sensing
means for processing a sound signal received from the sound sensing means in order
to determine whether the ball is kicked.
[0018] In an embodiment, the detection signal transmission system is a wireless transmission
system, in particular operating at a frequency that is suitable to transmit over a
distance of at least the distance of a diagonal of a play field. Considering that
the diagonal is the largest possible distance between the ball and a referee, a wireless
signal transmitted from the ball should at least be carried over such a distance.
In practice, a frequency of 433 MHz appeared to be suitable. A transmission frequency
may also be selected upon consideration of a requirement of a license to use such
a frequency.
[0019] In an embodiment the signaling system comprises a flag, the observable signal generator
being arranged in a part of the flag, in particular in a flag handle.
[0020] In an embodiment the signaling system comprises as an observable signal generator
at least one of an audible signal generator, a visible signal generator and a tangible
signal generator.
[0021] It is noted that the method and system according to the present invention may as
well be employed in determining a handball, i.e. a foul by touching the ball with
a hand. The method and system may also be employed for assisting a referee in determining
which player was the last player to touch the ball before the ball went outside the
play field.
[0022] Further, the method and system may be employed for assisting a referee in determining
whether a ball passed a goal line
[0023] Hereinafter, the invention is elucidated with reference to the appended drawings
showing non-limiting embodiments and wherein:
- Fig. 1A
- illustrates an embodiment of a method for generating a detection signal in accordance
with the present invention;
- Fig. 1B
- illustrates an embodiment of a method for generating an observable signal in accordance
with the present invention;
- Fig. 2A
- schematically shows a ball for use in an embodiment of a system according to the present
invention;
- Fig. 2B
- schematically shows a signaling system for use in an embodiment of a system according
to the present invention;
- Fig. 3
- shows a graph of a sound signal produced by a ball when kicked;
- Fig. 4
- schematically illustrates a ball in accordance with an embodiment of the present invention;
and
- Fig. 5
- schematically shows a handle of a flag for use in an embodiment of the present invention.
[0024] In the drawings, same reference numerals refer to same elements.
[0025] In Fig. 1A, a method is illustrated as a block diagram comprising a number of method
steps. Initially, a system for performing the method may be in a power safe mode 101
in order to prevent a low energy level, when the system is to be used.
[0026] Then, the system is started in step 102. The system may be started by switching the
system on using a suitable means, such as a start button or a remote controller. In
an embodiment, the system may be automatically started, when it is detected that apart
of the system, e.g. a ball, is moved.
[0027] In the method according to the present invention, a kick against a ball is to be
detected and to be signaled to a referee, in practice usually a linesman of a football
(soccer) game. When the ball is kicked, a sound is produced by the ball. In an embodiment
of the method, the sound may be sensed by a suitable sensor, such as a microphone,
as shown by step 103 in Fig. 1A. Of course, in other embodiments, the kick of the
ball may be detected by other suitable systems, such as a button to be activated by
a further referee, or by image processing.
[0028] The sound sensing means, e.g. the microphone, may be located at any suitable location.
In an embodiment, the sound sensing means is arranged in the ball. In such an embodiment,
a sound level of the sound produced by the ball is much higher than the sound level
of a sound produced in the surroundings, e.g. by the players and/or spectators. Hence,
the sound produced by the ball is easily distinguishable.
[0029] The sensed sound may be the sound produced due to a kick of the ball, including a
header or a contact by a knee or any other contact of a player with the ball, i.e.
any contact with a player that may lead to offside. However, the sensed sound may
as well be produced due to any other occurrence that may not lead to offside, such
as a sound when the ball hits the ground. Therefore, in step 104, the sensed sound
is processed in order to determine whether the sound was due to a kick. For example,
the sensed sound may be digitized using a suitable analog-to-digital (A/D) converter
and processed by a suitable microcontroller. The processing may include comparing
the sensed signal with a predetermined signal, which predetermined signal is the signal
of a kick of the ball. The processing may include, instead or additionally, spectral
analysis of the sensed sound signal. Also other processing techniques may be employed.
[0030] Based on the processing results, in step 105, it is determined whether the ball was
kicked, or not. If it is determined that the ball was kicked, a detection signal is
generated in step 106. If it is determined, in step 105, that the ball was not kicked,
the method returns to step 103.
[0031] Referring to Fig. 1B a signaling system for use in an embodiment of the method according
to the present invention may be in a power safe mode as indicated by method step 111.
In step 112, the signaling system may be activated from the power safe mode by pushing
a button or by any other suitable means.
[0032] Once activated, the signaling system is configured to receive a detection signal
as generated in accordance with the present invention, for example in accordance with
embodiment as illustrated by Fig. 1A.
[0033] Thus, in steps 113 and 114, the signaling system is sensing whether a detection signal
is received. If it is determined that the detection signal is received, an observable
signal is generated. Such an observable signal may be an audible signal, a visible
signal or a tangible signal, or a combination thereof. If it is determined that no
detection signal is received (step 114), the method returns to step 113.
[0034] Fig. 2A shows an embodiment of a system for generating a detection signal. The system
is comprised in a ball Ba. The system comprises an energy source ES
3a, a sensing means SM, a processing means PM and a transmission means TM.
[0035] The energy source ES
3a is configured to supply power to the other components. The energy source ES
3a may be any kind of suitable energy source, for example a battery, possibly a rechargeable
battery. As the system is comprised in a ball Ba, the battery may advantageously be
a small battery, e.g. a coin-shaped battery.
[0036] The sensing means SM may comprise a microphone for sensing a sound signal produced
by the ball Ba, when it is kicked. Instead or additionally, the sensing means SM may
comprise an acceleration sensor for measuring an acceleration of the ball Ba. Other
suitable sensing means SM may as well be employed, possibly in combination. The sensing
means SM outputs a sensed signal, e.g. a sound signal, and the sensed signal is supplied
to the processing means PM.
[0037] The processing means PM may process the sensed signal for determining from the sensed
signal whether the ball Ba was kicked. In an embodiment, the processing means PM solely
processes the sensed signal to prepare the sensed signal for transmission, thereby
lowering power consumption of the processing means PM. The processed sensed signal
is output by the processing means PM and is supplied to the transmission means TM.
[0038] The transmission means TM receives the output of the processing means PM and transmits
the output, for example through a wireless transmission channel. If the processing
means PM solely prepare the sensed signal for transmission, the transmission means
TM continuously transmits the output of the processing means PM. In such an embodiment,
the sensed signal is further processed at the receiver side, e.g. the signaling system,
as is explained hereinafter. In an embodiment, wherein the processing means PM solely
o,utputs, a detection signal, when it is determined that the ball Ba was kicked, the
transmission means TM only transmits now and then, i.e. at times that a detection
signal is output by the processing means PM. Thus, in such an embodiment, the power
consumption of the transmission means TM may be relatively low.
[0039] Referring to Fig. 2B, a signaling system may be comprised in a flag F1 of a linesman.
The signaling system may comprise a receiver means RM, a controller means CM, an actuator
Ac and an energy source ES
F1 for supplying power to the aforementioned components of the signaling system.
[0040] The receiver means RM is configured to receive a signal transmitted by the system
of Fig. 2A. The signal may be a signal comprising a sensed signal and/or a detection
signal as above described.
[0041] The controller means CM is configured to receive the received signal from the receiver
means RM. The controller means CM determines from the received signal whether the
ball Ba (Fig. 2A) was kicked. In case the received signal comprises a detection signal,
the controller means CM may directly determine that the ball Ba was kicked. If the
received signal does not comprise a detection signal, but does comprise the sensed
signal, the controller means CM may comprise a processor for processing the sensed
signal in order to determine whether the ball Ba was kicked based on the sensed signal.
If it is determined that the ball Ba was kicked, an actuation signal is transmitted
to the actuator Ac, which in response generates an observable signal. The actuator
Ac may be a light output device, e.g. a lamp or LED, a sound generating device or
a vibration generating device for generating a tangible signal, for example. A vibration
generating device may be an eccentric motor means, for example.
[0042] Fig. 3 shows a graph of a sound signal produced by a ball when the ball is kicked.
The horizontal axis represents time in milliseconds; the vertical axis represents
a sound level (amplitude) on a logarithmic scale. Based on the amplitude and/or frequency
content of the sound signal, e.g. using spectral analysis, it may be determined what
caused the signal, in particular whether the sound signal was due to a kick against
the ball.
[0043] Fig. 4 shows a cross-section of a ball Ba in accordance with an embodiment of the
present invention. The ball Ba comprises an inner ball IB and an outer ball OB. Between
the inner ball IB and the outer ball OB a detection system circuit DSC is positioned.
The detection system circuit DSC may comprise the components as shown in Fig. 2A,
i.e. an energy source ES
Ba, a sensing means SM, a processing means PM and a transmission means TM.
[0044] The detection system circuit DSC may be arranged on a flexible printed circuit board
(PCB) such that the PCB may assume a rounded/spherical shape in accordance with the
round/spherical shape of the ball. In an embodiment, the PCB is not flexible, but
is preshaped in accordance with the shape of the ball Ba. The energy source, e.g.
a coin shaped battery, may be arranged on a first side of the PCB and preferably positioned
between the outer ball OB and the PCB. The electronic components, e.g. a sensing means,
a processing means and/or a transmission means, are preferably arranged at a second,
side of the PCB, the second side being opposite to the first side, i.e. between the
inner ball IB and the PCB. Thus, the battery may protect the electronic components
against damage due to a kick at the ball Ba.
[0045] The transmission means of the detection system circuit DSC may comprise an antenna,
in particular a loop antenna, for transmitting a detection signal or a detected signal.
The loop antenna may be substantially two-dimensionally shaped and arranged on the
PCB. The dimensions of the loop antenna may be, for example, 35 x 20 mm or 50 x 30
mm. The smaller antenna having dimensions 35 x 20 mm has a suitable transmission range
and may be preferred due to its dimensions. The larger antenna having dimensions 50
x 30 mm is relatively large, but may be preferred due to its relatively low energy
consumption.
[0046] A motion detection element may also be comprised in the detection system circuit
DSC. For example, a piezo element may be arranged between the inner ball IB and the
PCB. When the ball Ba starts to move, pressure is applied to the piezo element, which
in response outputs an electrical signal. The electrical signal may be employed to
indicate that the ball Ba is moving and the detection system is to leave a power safe
mode (Fig. 1A) and to start.
[0047] It is noted that regulations may limit a weight of the ball Ba. Further, a relatively
large weight at one side of the ball Ba may influence the behaviour of the ball Ba.
Therefore, suitable lightweight components may be used. For example, the electronic
components may be made from SMD components. In such a practical embodiment, the weight
of the DSC may be about 10 g.
[0048] Fig. 5 shows a flag handle FH of a flag to be used by a linesman, i.e. one of the
referee's, during a football (soccer) match. The flag handle FH comprises a signaling
system in accordance with the present invention and may, for example, be used in combination
with the ball Ba as illustrated in Fig. 4.
[0049] Referring to Fig. 5, the flag handle FH comprises a battery level indicator LI indicating
an energy level of a battery comprised in the flag handle FH and/or a energy level
of the battery comprised in the ball Ba in order to prevent that either battery energy
level will become too low for operation during a match.
[0050] The flag handle FH may further comprise a switch SW for switching the signaling system
on or off. The switch SW may be a push button, for example. Thus, the linesman may
push the switch SW, when a possible offside situation occurs such that the signaling
system only provides the observable signal in such a situation instead of during the
whole match.
[0051] The flag handle FH may further comprise a ball selector switch BS. Presuming that
the flag handle FH is to operate with the ball Ba as shown in Fig. 4, each ball Ba
may have an identification code. The identification code may be transmitted with the
transmitted signals. The use of an identification code prevents that signals from
any other ball, not used in the match, are received and interpreted, which could lead
to misjudgments. The ball selector switch BS allows to use the flag and flag handle
FH in combination with a number of balls.
[0052] In order to enable the signaling system of the flag handle FH to be used in combination
with a further number of balls, the flag handle FH may comprise a memory reader MR
e.g. comprising a subscriber identity module (SIM) card reader. The memory reader
MR may receive and read a memory card SIM. On the memory card one or more identification
codes of a number of corresponding balls is stored. In combination with the ball selector
switch SW, for example, the identification code of the ball to be used in the match
may be selected from the memory card.
[0053] The method and system according to the present invention may as well be advantageously
used for assisting a referee to determine which player had the last contact with the
ball. The method and system allow determining whether an apparent contact with the
ball was an actual contact with the ball, since the method and system may indicate
when there is a contact with the ball. Similarly, the method and system may assist
in detecting a handball, i.e. a contact of a hand with the ball. Such a contact detection
method and system may as well be employed for assisting a referee in other games and
sports, such as volleyball.
[0054] Although detailed embodiments of the present invention are disclosed herein, it is
to be understood that the disclosed embodiments are merely exemplary of the invention,
which can be embodied in various forms. Therefore, specific structural and functional
details disclosed herein are not to be interpreted as limiting, but merely as a basis
for the claims and as a representative basis for teaching one skilled in the art to
variously employ the present invention in virtually any appropriately detailed structure.
Further, the mere fact that certain measures are recited in mutually different dependent
claims does not indicate that a combination of these measures cannot be used to advantage.
[0055] Further, the terms and phrases used herein are not intended to be limiting; but rather,
to provide an understandable description of the invention. The terms "a" or "an",
as used herein, are defined as one or more than one. The term another, as used herein,
is defined as at least a second or more. The terms including and/or having, as used
herein, are defined as comprising (i.e., open language). The term coupled, as used
herein, is defined as connected, although not necessarily directly.
1. Method for detecting an offside situation during a soccer game, the method comprising:
- generating a detection signal when a ball is kicked by a first player;
- supplying the detection signal to a signaling system; and
- generating by the signaling system an observable signal to be observed by a referee,
in response to receipt of the detection signal.
2. Method according to claim 1, wherein the method further comprises:
- detecting a position of a second player by the referee at the moment of observation
of the observable signal.
3. Method according to claim 1 or 2, wherein the method further comprises:
- sensing a sound signal produced by the ball;
- processing the sound signal in order to determine whether the ball is kicked;
- if it is determined that the ball is kicked, generating the detection signal.
4. Method according to any of the preceding claims, wherein generating a detection signal
comprises:
- compiling a content signal of the detection signal, the content signal of the detection
signal comprising at least one element of the group comprising detected sound information
data and a ball identification code.
5. Method according to any one of the preceding claims, wherein the method further comprises:
generating the detection signal in the ball; and
wirelessly transmitting the detection signal from the ball to the signaling system.
6. Method according to any one of the preceding claims, wherein the observable signal
comprises a signal selected from the group comprising an audible signal, a visual
signal, and a tangible signal.
7. Method according to claim 6, wherein the observable signal comprises a tangible signal,
and the step of generating an observable signal comprises:
- generating a vibration in an object to be in contact with a body part of the referee,
the object e.g. being a flag handle or a wrist device.
8. System for detecting an offside situation during a soccer game, the system comprising:
- a detection signal generator for generating a detection signal when a ball is kicked
by a player;
- a detection signal transmission system for supplying the detection signal from the
detection signal generator to a signaling system;
- an observable signal generator comprised in the signaling system for generating,
in response to receipt of the detection signal, an observable signal to be observed
by a referee.
9. System according to claim 8, wherein the detection signal generator is arranged in
the ball.
10. System according to claim 8 or 9, wherein the detection signal generator comprises:
- a sound sensing means, in particular a microphone; and
- a sound processing means coupled to the sound sensing means for processing a sound
signal received from the sound sensing means in order to determine whether the ball
is kicked.
11. System according to any one of the claims 8 - 10, wherein the detection signal transmission
system is a wireless transmission system, in particular operating at a frequency that
is suitable to transmit over a distance of at least the distance of a diagonal of
a play field.
12. System according to any one of the claims 8-11, wherein the signaling system comprises
a flag, the observable signal generator being arranged in a part of the flag, in particular
in a flag handle.
13. System according to claim 12, wherein the signaling system comprises as an observable
signal generator at least one of an audible signal generator, a visible signal generator
and a tangible signal generator.