Note: Descriptions are shown in the official language in which they were submitted.
CA 02916488 2015-12-30
Description
Method for detecting when a snowmobile falls through ice
The present invention relates to a method for detecting
when a snowmobile falls through ice and to a computing
unit, a snowmobile and a computer program for carrying
out said method.
Prior art
Tracked vehicles for movement in snow are usually
referred to as snowmobiles. Snowmobiles can also be moved
on frozen water covered by a layer of ice. In this case,
there is the risk of this layer of ice breaking, the
snowmobile falling through the ice and sinking in the
water underneath. If the snowmobile falls through ice,
this may result in a mortal danger for the driver of the
snowmobile. This danger is increased, in particular, at
times of the year at which the weather slowly becomes
warmer and the outside temperatures increase and layers
of ice therefore become thinner.
Properties of the terrain on which the snowmobile is
moved can often change quickly. It proves to be extremely
difficult, even for experienced drivers, to always be
aware of the substrate on which the snowmobile is
operated. Even experienced drivers often do not notice
that they are moving the snowmobile over frozen water and
that there is possibly the risk of the snowmobile falling
through.
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It is therefore desirable to provide a possible way of
detecting when a snowmobile falls through ice in order to
be able to initiate corresponding measures.
Disclosure of the invention
The invention proposes a method for detecting when a
snowmobile falls through ice having the features of the
disclosure. The disclosure and the following description
relate to advantageous configurations.
A snowmobile is in the form of a tracked vehicle, in
particular, and also has, in particular, an expedient
drive which provides a drive torque. Such a drive may be
in the form of an internal combustion engine or an
electric motor, for example. This drive torque is
transmitted to a track drive shaft, in particular, via a
transmission, for example a continuously variable
transmission (CVT). A snowmobile is operated, in
particular, in snow, on snow-covered terrain or else on
frozen water covered by a layer of ice. In particular, a
snowmobile is operated on unprepared terrain, also on
alpine, hilly or mountainous terrain, in particular.
During ongoing operation of the snowmobile, at least one
inertial sensor determines measured values of at least
one movement variable of the snowmobile. An inertial
sensor can be understood as meaning, in particular,
sensors which determine an acceleration and/or a rotation
rate of the snowmobile. In particular, the inertial
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Date Recue/Date Received 2023-01-16
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sensor may be in the form of an acceleration sensor or a
translation sensor and/or in the form of a rotation rate
sensor or a gyroscopic sensor. In particular, the
measured values are metrologically recorded directly as
sensor values by the inertial sensor or are determined or
calculated from metrologically recorded sensor values.
The determined measured values are monitored in order to
determine whether the result is a pattern which indicates
that the snowmobile has fallen through ice. For this
purpose, the determined measured values are assessed or
monitored, in particular, using assessment criteria. In
particular, scalar measured values and/or a temporal
profile of the measured values is/are monitored for this
purpose. Such a pattern can be understood as meaning, in
particular, that specific measured values which are
typical or characteristic of the snowmobile falling
through ice are determined for the at least one movement
variable. If these specific measured values are
determined for the at least one movement variable, it can
be inferred that the snowmobile has fallen through. In
particular, the measured values of a specific combination
of movement variables are monitored.
If such a pattern is detected, it may possibly not yet be
inferred with absolute certainty that the snowmobile has
fallen through. For example, the snowmobile may only have
been abruptly stopped, the snowmobile may only have
overturned, for example, or may have jumped over a hill
or a ski jump. In order to be able to nevertheless
determine with certainty whether the snowmobile has
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fallen through ice if such a pattern is detected, a
second evaluation is also carried out.
If the result is such a pattern which indicates that the
snowmobile has fallen through ice, a current movement of
the snowmobile is compared with a movement of the
snowmobile predicted from a previous movement of the
snowmobile. A previous movement should be understood as
meaning, in particular, a movement which was carried out
by the snowmobile in a defined interval of time before
detecting the pattern, in particular in an interval of
time of one second, five seconds or ten seconds, for
example.
As the predicted movement, a movement, according to which
the snowmobile is moved along with substantially
identical or similar movement parameters or values of
movement variables of the previous movement, is
extrapolated, in particular. Alternatively
Or
additionally, a movement, according to which the
snowmobile comes to a standstill or is moved along at a
reduced, lower speed, is determined as the predicted
movement, in particular.
If the current movement of the snowmobile does not differ
from the predicted movement of the snowmobile or differs
only marginally or only up to a certain degree, this
means that the snowmobile has not fallen through the ice.
If the current movement differs from the predicted
movement by more than a certain degree, this indicates
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that the snowmobile has fallen through and a fall is
detected.
The invention is an effective and low-cost possible way
of reliably detecting when a snowmobile falls through in
good time and of distinguishing said fall from other
similar movement patterns, in particular. The safety for
a driver can therefore be increased. The risk of a life-
threatening situation for the driver can be detected as
quickly as possible. Expedient measures can be carried
out as quickly as possible in order to prevent sinking of
the snowmobile and in order to ensure that the driver
survives. The additional evaluation in order to determine
whether the snowmobile has actually fallen through makes
it possible to prevent it from being incorrectly detected
that the snowmobile has fallen through.
The invention can be implemented in a simple manner in
conventional snowmobiles. In particular, no additional
components are usually needed to implement the invention.
Components implemented in a conventional snowmobile, for
example conventional inertial sensors, can also be used
to carry out the invention.
The method according to the invention can preferably be
carried out by a control device of the snowmobile.
Snowmobiles can therefore be easily retrofitted.
Furthermore, a special computing unit can also be
provided for the purpose of carrying out the method
according to the invention. Such a computing unit is in
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the form of a microcontroller or an ASIC (application-
specific integrated circuit), in particular.
The measured values of the movement variables are usually
determined during ongoing operation of the snowmobile
anyway and are usually present in control devices of the
snowmobile. For this purpose, sensor values from sensors
or microsystems (microelectromechanical system, MEMS), in
particular, are recorded in the snowmobile and are
transmitted to control devices of the snowmobile via a
suitable communication system (for example a field bus
system, in particular a CAN bus system).
It is noted at this juncture that the invention is
equally suitable for other vehicles, in particular for
vehicles which are operated on rough, unprepared terrain.
For example, the invention is similarly suitable for ATVs
(all terrain vehicle) or quads.
A safety measure is advantageously carried out when it is
detected that the snowmobile has fallen through ice. Such
safety measures are automatically carried out. There is
therefore no need for a driver of the snowmobile himself
to have to manually initiate corresponding safety
measures, which he may possibly not be able to do at all
on account of stress or shock.
An inflatable float or an airbag, which prevents the
snowmobile from sinking in the water, is preferably
inflated as a safety measure. This float may be arranged,
for example, under a seat or in a nose of the snowmobile
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or at another expedient location in the snowmobile. For
example, a lifejacket and/or a lifebelt may also be
inflated for the driver. Alternatively or additionally,
an emergency signal may also be emitted as a safety
measure. During this emergency signal, it is possible to
transmit, in particular, coordinates at which the
snowmobile has fallen through. These coordinates can be
determined using a GPS system, for example.
Measured values of at least one movement-specific
measurement variable are preferably determined as the
measured values of the at least one movement variable.
Such movement-specific measurement variables describe a
movement of the snowmobile or driving parameters of the
snowmobile. In particular, such movement-specific
measurement variables are a speed of the snowmobile, a
drive torque provided by a drive of the snowmobile, a
rotational speed of the drive (for example an internal
combustion engine or an electric motor), a voltage
applied to an electric motor or a drive current, a
steering direction and/or a bend radius.
An acceleration, in particular a linear acceleration in
one of the three spatial directions or along one of the
three axes of extent of the snowmobile (longitudinal,
transverse, vertical axis), is preferably determined as
the measured value. In particular, measured values for a
direction of movement or for the movement of the
snowmobile can also be determined. In particular, this
direction of movement or movement can describe how the
snowmobile moves, for example along an incline or a
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slope, uphill, downhill, transversely with respect to a
slope, along a plane, straight ahead, along a bend, etc.
Alternatively or additionally, measured values of at
least one orientation-specific measurement variable are
preferably determined as the measured values of the at
least one movement variable. Such orientation-specific
measurement variables describe, in particular, a spatial
orientation of the snowmobile, also in particular how the
snowmobile is oriented with respect to the substrate.
An inclination angle of the snowmobile with respect to a
defined axis and/or a rotation rate, that is to say a
roll, pitch and yaw rate, also in particular
corresponding roll, pitch and yaw angles, is/are
preferably determined as the measured value. An angular
velocity of a rotational movement about one of the three
spatial directions or about one of the three axes of
extent of the snowmobile (longitudinal, transverse,
vertical axis), in particular, is determined as the
rotation rate.
When monitoring the determined measured values, a check
is advantageously carried out in order to determine
whether the determined measured values reach a threshold
value. In particular, a threshold value specific to the
respective movement variable is used for measured values
of each different movement variable. These threshold
values are values typical of a fall.
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A check is preferably carried out in order to determine
whether an acceleration in the z direction, in particular
an acceleration in the direction of the earth's center,
exceeds a limit value. This indicates, in particular,
that the snowmobile is sinking in the water.
Alternatively or additionally, a check is preferably
carried out in order to determine whether a negative
acceleration or deceleration in the x and/or y direction,
that is to say within the plane in which the snowmobile
moves during a regular movement, respectively exceeds a
limit value. A check is therefore carried out in order to
determine whether the snowmobile is decelerated sharply
within this plane.
For example, a check can also be carried out in order to
determine whether one of the rotation rates reaches a
threshold value. A check is preferably carried out in
order to determine whether the roll rate about the
longitudinal axis of the snowmobile and/or the pitch rate
about the transverse axis of the snowmobile respectively
reach(es) a limit value.
Alternatively or additionally, a check is advantageously
carried out in order to determine whether the determined
measured values change within a defined interval of time
by more than a permissible tolerance threshold, for
example by more than a defined percentage, for example by
more than 25%, more than 50% or more than 75%. For
example, a check is carried out in order to determine
whether the speed in the x and/or y direction changes
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comparatively greatly within a comparatively short
interval of time (for example half a second or one
second), which indicates unwanted, abrupt deceleration
and not a desired braking process.
In order to compare the current movement with the
predicted movement, current measured values of the at
least one movement variable are advantageously compared
with previous measured values of the at least one
movement variable. It is possible to monitor the same
movement variables as those which are also monitored for
the pattern. However, other expedient movement variables
can also be monitored in order to compare the movements.
It is detected that the snowmobile has fallen through ice
when the current measured values differ from the previous
measured values by more than a permissible tolerance
threshold, for example a defined percentage, for example
by more than 25%, by more than 50% or by more than 75%.
It is therefore assessed, in particular, whether the
snowmobile, during the current movement, is moved along
in a substantially identical or similar manner to the
previous movement. If the current and previous measured
values differ from one another by more than the
permissible tolerance threshold, this indicates, in
particular, that the movement or the direction of
movement of the snowmobile has changed considerably. It
is therefore verified or detected, in particular, that
the snowmobile has fallen through ice.
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The previous measured values were preferably determined
within a defined interval of time before detecting the
pattern, in particular in an interval of time of one
second, five seconds or ten seconds.
In order to compare the current movement with the
predicted movement, current measured values of an
acceleration in the z direction are advantageously
compared with previous measured values of the
acceleration in the z direction. A comparatively high
acceleration in the z direction of the current movement,
which differs from the corresponding acceleration of the
previous movement by the defined percentage, indicates,
in particular, that the snowmobile has fallen through and
is sinking in the water.
According to one advantageous embodiment of the
invention, during ongoing operation of the snowmobile,
measured values of at least one terrain-specific
measurement variable are determined in addition to the
measured values of the at least one movement variable of
the snowmobile.
Such terrain-specific measurement variables describe a
terrain on which the snowmobile is operated. Such
measurement variables are, in particular, a terrain slope
and/or a nature of the substrate, for example whether the
substrate of the snowmobile is snow or ice. In
particular, this terrain-specific measurement variable
indicates whether or not the terrain is frozen water.
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In order to determine measured values of such measurement
variables, GPS information, in particular, can be
evaluated. Furthermore, topographical map information or
map data, in particular, can be evaluated using such GPS
information. Such map information or map data can be
stored in a control device of the snowmobile, for
example.
The measured values of the terrain-specific measurement
variable and of the movement variable are monitored
together in order to determine whether the result is a
pattern which indicates that the snowmobile has fallen
through ice. Monitoring the terrain-specific measurement
variable also makes it possible to carry out a
preliminary selection, in particular. For example, as
soon as the measured values of the terrain-specific
measurement variable indicate that the snowmobile is
being moved on frozen water, the determined measured
values of the at least one movement variable can be
monitored in order to determine whether a corresponding
pattern results.
Alternatively or additionally, measured values of at
least one terrain-specific measurement variable are
advantageously taken into account in order to compare the
current movement of the snowmobile with the predicted
movement of the snowmobile. In particular, it is possible
to take into account or assess in this case whether the
snowmobile, during the current movement, moves along on
the terrain and, in particular, moves away from the
frozen water. In particular, if the measured values of
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the terrain-specific measurement variable and therefore
the terrain no longer change, it can be concluded that
the snowmobile no longer moves along and has fallen
through ice.
A computing unit according to the invention, for example
a control device of a snowmobile, is set up, in
particular in terms of programming, to carry out a method
according to the invention. A snowmobile according to the
invention has such a computing unit.
The implementation of the method in the form of software
is also advantageous since this gives rise to
particularly low costs, in particular if an executing
control device is also used for further tasks and is
therefore present anyway. Suitable data storage media for
providing the computer program are, in particular, floppy
disks, hard disks, flash memories, EEPROMs, CD-ROMs, DVDs
and so on. It is also possible to download a program via
computer networks (Internet, intranet etc.).
Further advantages and configurations of the invention
emerge from the description and the accompanying drawing.
It goes without saying that the features mentioned above
and the features yet to be explained below can be used
not only in the respectively stated combination but also
in other combinations or alone without departing from the
scope of the present invention.
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The invention is schematically illustrated in the drawing
using exemplary embodiments and is described below with
reference to the drawing.
Brief description of the drawings
Figure 1 schematically shows a preferred configuration of
a snowmobile which is set up to carry out a
preferred embodiment of a method according to
the invention.
Figure 2 schematically shows a preferred embodiment of a
method according to the invention in the form of
a block diagram.
Embodiment(s) of the invention
A preferred configuration of a snowmobile is
schematically illustrated in figure 1 and is denoted by
100. In this case, figure la schematically illustrates
the snowmobile 100 in a perspective view, and figure lb
illustrates the snowmobile in a side view.
The snowmobile has two runners 101 and 103. Each of the
runners 101 and 103 is connected to a frame or housing
106 of the snowmobile 100 via a respective suspension 102
and 104. The runners 101 and 103 can be oriented using a
steering system 105 and a steering direction can
therefore be predefined.
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The snowmobile also has a drive 110. In this example, the
drive is in the form of an internal combustion engine
110. The internal combustion engine 110 provides a drive
torque which is transmitted to a track drive shaft via a
transmission 111, for example a continuously variable
transmission. The drive torque is therefore transmitted
to a track 112 of the snowmobile 100.
The snowmobile 100 also has a control device 120. A
communication system, for example a CAN bus 121, is also
implemented in the snowmobile 100. The control device 120
is connected to different sensors and actuators via this
CAN bus 121.
In particular, inertial sensors in the form of an
acceleration sensor 131 and a rotation rate sensor 132
are provided. The acceleration sensor 131 can be used to
determine measured values for an acceleration of the
snowmobile 100 along the three spatial directions or axes
of extent 150 of the snowmobile 100 (longitudinal axis
151, transverse axis 152, vertical axis 153). The
rotation rate sensor 132 can be used to determine
measured values for a rotation rate or angular velocity
of the snowmobile 100 about the three axes of extent 150.
A GPS sensor 133 is also present in the embodiment shown
and is used to determine measured values for a terrain-
specific measurement variable. These measured values
describe, in particular, the terrain on which the
snowmobile 100 is operated and indicate, in particular,
whether the snowmobile 100 is being moved on (frozen)
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water. In particular, GPS information from the GPS sensor
133 is used to evaluate topographical map information or
map data in order to determine these measured values.
Such map information or map data may be stored in the
control device 120, for example.
A float 140 or an airbag is arranged in a seat 107. This
float 140 is inflated if the snowmobile has fallen
through ice and is in the water. The float 140 may also
be arranged, for example, in a nose of the snowmobile or
at another expedient location in the snowmobile or on the
driver (for example vest).
In order to detect whether the snowmobile 100 has fallen
through ice if it is moved over frozen water, for
example, the snowmobile is set up to carry out a
preferred embodiment of a method according to the
invention. In particular, the control device 120 is set
up to carry out this preferred embodiment of the method
according to the invention which is schematically
illustrated in figure 2 as a block diagram.
In a step 201, measured values for the terrain-specific
measurement variable are determined by the GPS sensor
133. At the same time, in a step 202, measured values for
the accelerations of the snowmobile 100 along the three
axes of extent 150 are determined by the acceleration
sensor 131. The rotation rate sensor 132 determines
measured values for the rotation rates of the snowmobile
100 about the three axes of extent 150.
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In a step 203, these determined measured values are
monitored in order to determine whether the result is a
pattern which indicates that the snowmobile 100 has
fallen through ice.
During this monitoring 203, the determined measured
values for the terrain-specific measurement variable are
monitored in a step 204. In particular, it is monitored
in this case whether the snowmobile 100 is being moved on
(frozen) water.
At the same time, the measured values determined by the
inertial sensors 131 and 132 are monitored in a step 205.
In this case, it is monitored whether the measured values
of the deceleration (that is to say the negative
acceleration) along the longitudinal and transverse axes
151 and 152 each exceed a limit value. It is also
monitored whether the measured values for the
acceleration along the vertical axis 153 in the direction
of the earth's center exceed a limit value. It is also
monitored whether a roll rate (that is to say the
rotation rate about the longitudinal axis 151) and a
pitch rate (the rotation rate about the transverse axis
152) respectively exceed a limit value.
As soon as the measured values of at least one of these
movement variables exceed the respective limit value and
if the measured values of the terrain-specific
measurement variable reveal that the snowmobile 100 is
being moved on water, a pattern which indicates that the
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snowmobile has fallen through ice is detected in step
206.
In this case, an evaluation is carried out in a step 207
in order to determine whether the snowmobile 100 has
actually fallen through ice. For this purpose, a
predicted movement of the snowmobile 100 is determined
from a previous movement of the snowmobile 100 in a step
208.
For this purpose, previous measured values for the
acceleration of the snowmobile 100 along the axes of
extent 150 are read in from a memory area of the control
device 120, which measured values were determined in an
interval of time of one second, for example, before
detecting the pattern according to step 206 (indicated by
reference symbol 209). In addition, previous measured
values for the orientation-specific measurement variable
of the snowmobile 100 are read in (likewise indicated by
reference symbol 209). The terrain on which the
snowmobile 100 was moved within the interval of time of
one second before detecting the pattern according to step
206 is therefore determined, in particular.
A movement which is still continued with these previous
measured values for the acceleration of the snowmobile
100 along the axes of extent 150 on the determined
terrain is determined as the predicted movement of the
snowmobile 100.
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In a step 210, the acceleration sensor 131 determines
current measured values for the acceleration of the
snowmobile 100 along the axes of extent 150 and the GPS
sensor 133 determines current measured values for the
terrain-specific measurement variable.
In a step 211, the previous measured values and the
current measured values are compared with one another.
For example, it is monitored whether the measured values
of each of the three accelerations along the axes of
extent 150 differ from one another at least by 25% as the
permissible tolerance threshold. In this case, the
current movement of the snowmobile 100 differs from the
predicted movement of the snowmobile 100 to such an
extent that it can be assumed that the snowmobile 100 has
fallen through ice.
In particular, it is monitored whether the current
acceleration along the longitudinal axis 151 and along
the transverse axis 152 has decreased in comparison with
the corresponding previous accelerations by at least 25%
in each case as the tolerance threshold, which indicates
sharp deceleration of the snowmobile 100 within the plane
in which the snowmobile 100 is moved during the regular
movement.
It is also monitored whether the current acceleration
along the vertical axis 153 has increased in comparison
with the corresponding previous acceleration by at least
25% as the permissible tolerance threshold, for example,
which signifies sharp acceleration of the snowmobile 100
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in this direction. This indicates that the snowmobile 100
has fallen into water.
A check is also advantageously carried out in order to
determine whether the current and previous measured
values of the terrain-specific measurement variable
differ and whether the snowmobile is therefore moved
along in the terrain. If these measured values do not
change or scarcely change, the snowmobile is not moved
along, which indicates that the snowmobile 100 has fallen
through ice.
If these comparisons according to step 211 reveal that
the current and previous measured values of the
individual accelerations differ from one another by more
than the permissible tolerance threshold and that the
measured values of the terrain-specific measurement
variable do not change or scarcely change, the current
movement of the snowmobile differs from the predicted
movement of the snowmobile. It is therefore detected that
the snowmobile 100 has fallen through ice in step 212.
In this case, the float 140 is inflated as a safety
measure in step 213. Alternatively or additionally, a
lifejacket and/or a lifebelt can also be inflated for the
driver. Sinking of the snowmobile 100 is therefore
prevented. Furthermore, the control device 120 emits an
emergency signal via an expedient radio connection.
During this emergency signal, the current GPS coordinates
of the snowmobile 100 which are determined by the GPS
sensor 133 are likewise transmitted.
