U.S. patent application number 10/498251 was filed with the patent office on 2005-07-14 for vibration control system and improvements in or relating to skis.
Invention is credited to Watson, Peter.
Application Number | 20050151350 10/498251 |
Document ID | / |
Family ID | 9927384 |
Filed Date | 2005-07-14 |
United States Patent
Application |
20050151350 |
Kind Code |
A1 |
Watson, Peter |
July 14, 2005 |
Vibration control system and improvements in or relating to
skis
Abstract
Vibration control systems are described which provide for the
variation in stiffness and damping in a structure. The systems are
based on the use of rheological fluid, with examples provided of
magnetorheological fluid flex actuators and semi-active damping
systems. An adaptive vibration control system is also described
incorporating sensors, a signal processor and a power supply
together with the fluid flex actuators and semi-active damping
systems. Embodiments are described for use in and with skis.
Inventors: |
Watson, Peter; (Richmond
N.Yorkshire, GB) |
Correspondence
Address: |
Fleshner & Kim
Suite 1100
2325 Dulles Corner Boulevard
Herndon
VA
20171
US
|
Family ID: |
9927384 |
Appl. No.: |
10/498251 |
Filed: |
March 23, 2005 |
PCT Filed: |
December 10, 2002 |
PCT NO: |
PCT/GB02/25551 |
Current U.S.
Class: |
280/602 |
Current CPC
Class: |
A63C 5/075 20130101;
F16F 9/53 20130101; A63C 5/07 20130101 |
Class at
Publication: |
280/602 |
International
Class: |
A63C 005/07 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 11, 2001 |
GB |
0129588.0 |
Claims
1-39. (canceled)
40. A vibration control system, the system comprising a mounting
surface upon which is located a flexible hose, the hose having a
first cross-sectional area filled with a rheological fluid and ends
abutted to the surface.
41. A vibration control system as claimed in claim 40, wherein the
rheological fluid is an electrorheological fluid which undergoes a
change in viscosity proportional to a change in electric field.
42. A vibration control system as claimed in claim 40, wherein the
rheological fluid is a magnetorheological fluid which undergoes a
change in viscosity proportional to a change in applied magnetic
field.
43. A vibration control system as claimed in claim 40, wherein a
plurality of hoses are located on the surface.
44. A vibration control system as claimed in claim 43, wherein the
hoses are located symmetrically on the surface.
45. An adaptive vibration control system, the system comprising
sensing means to determine one or more environmental
characteristics, a signal processor to determine a controlling
response to the characteristics and vibration control means
responsive to the controlling response to counter vibration.
46. An adaptive vibration control system as claimed in claim 45,
wherein the vibration control means comprises a structure including
a chamber and a means for creating a variable applied field within
the chamber, wherein the chamber is substantially filled with a
theological fluid which under the influence of the applied field
causes a variation in the stiffness of the structure.
47. An adaptive vibration control system as claimed in claim 45,
wherein the vibration control means comprises a mounting surface
upon which is located a flexible hose, the hose having a first
cross-sectional area filled with a rheological fluid and ends
abutted to the surface.
48. An adaptive vibration control system as claimed in claim 45,
wherein the sensing means is at least one sensor.
49. An adaptive vibration control system as claimed in claim 45,
wherein the sensing means is a multi-sensor array.
50. An adaptive vibration control system as claimed in claim 45,
wherein the multi-sensor array is a distributed array of PVDF
piezo-sensors.
51. An adaptive vibration control system as claimed in claim 45,
wherein the adaptive vibration control system includes a power
supply located adjacent the system, the power supply including a
piezo material such that movement of the material creates an
electric signal.
52. A ski, the ski including a vibration control system, the system
comprising sensing means to determine one or more environmental
characteristics, a signal processor to determine a controlling
response to the characteristics and vibration control means
responsive to the controlling response to counter vibration.
53. A ski as claimed in claim 52, wherein the vibration control
means comprises a structure including a chamber and a means for
creating a variable applied field within the chamber, wherein the
chamber is substantially filled with a theological fluid which
under the influence of the applied field causes a variation in the
stiffness of the ski.
54. A ski as claimed in claim 52, wherein the vibration control
means comprises a mounting surface upon which is located a flexible
hose, the hose having a first cross-sectional area filled with a
theological fluid and ends abutted to the surface.
55. A ski as claimed in claim 52, wherein the vibration control
system comprises vibration control means comprising a structure
including a chamber and a means for creating a variable applied
field within the chamber, wherein the chamber is substantially
filled with a theological fluid which under the influence of the
applied field causes a variation in the stiffness of the ski, and
vibration control means comprising a mounting surface upon which is
located a flexible hose, the hose having a first cross-sectional
area filled with a theological fluid and ends abutted to the
surface to vary damping of the ski.
56. A ski as claimed in claim 52, wherein the sensing means is a
multi-sensor array being a distributed array of PVDF
piezo-sensors.
57. A ski as claimed in claim 52, wherein the sensing means is
sensor arrays positioned at modal points on the ski.
58. A ski as claimed in claim 52, wherein the vibration control
means are located a modal points on the ski.
59. A ski as claimed in claim 52, further comprising a power supply
comprising a layered piezo-ceramic, and wherein power generation
comes from a skier's movement over the ski acting on the
piezo-ceramic.
Description
[0001] The present invention relates to vibration control systems
and in particular, though not exclusively, to an adaptive control
system to vary flex and damping in skis during use.
[0002] It is known that vibration of an object can be suppressed in
objects manufactured with a calculated stiffness and damping.
However, when the object is subjected to a range of operating
conditions the frequency of vibration can vary i.e. the bandwidth
increases. Objects having a fixed stiffness and damping cannot
suppress vibration at varying frequencies and as a result the
object is prone to vibration with deleterious effect.
[0003] An area where vibration reduces performance is in skiing.
Vibration causes a ski to `chatter` and so loose edge contact.
Manufacturers have engineered skis by varying geometry, materials
and construction techniques in an effort to suppress vibration, but
such skis tend to be limited to use in certain environments. For
example, male downhill race skiers use skis which have a high
stiffness whereas recreational skiers have more flexible skis. It
is recognised that it would be advantageous to provide a ski in
which the stiffness and damping could be varied during use and so
improve the handling of a ski in a range of environments.
[0004] It is an object of at least one embodiment of the present
invention to provide a vibration control system which includes
active flex control to vary the stiffness of an object during
use.
[0005] It is a further object of at least one embodiment of the
present invention to provide a vibration control system which
includes a semi-active damping system to change the damping level
so as to optimally counteract motion with a controlled resistive
motion.
[0006] It is a yet further object of at least one embodiment of the
present invention to provide a vibration control system which
automatically adapts to surrounding conditions to provide active
vibration control.
[0007] It is an object of at least one embodiment of the present
invention to provide a ski including active flex control.
[0008] It is a further object of at least one embodiment of the
present invention to provide a ski including a semi-active damping
system.
[0009] It is a yet further object of at least one embodiment of the
present invention to provide a ski having automatic adaptive
control of stiffness and damping during use.
[0010] According to a first aspect of the present invention there
is provided a vibration control system, the system comprising a
structure including a chamber and a means for creating a variable
applied field within the chamber, wherein the chamber is
substantially filled with a rheological fluid which under the
influence of the applied field causes a variation in the stiffness
of the structure.
[0011] The rheological fluid may be an electrorheological fluid
which undergoes a change in viscosity proportional to a change in
electric field. Advantageously the rheological fluid is a
magnetorheological fluid which undergoes a change in viscosity
proportional to a change in applied magnetic field.
[0012] Preferably the applied field is a continuously variable
applied field.
[0013] Preferably, the means for creating a variable applied field
comprises an electromagnetic coil. A variable power source may be
applied to the coil.
[0014] The structure may include a first member having a first
surface and a second member having a second surface, the surfaces
being inner walls of the chamber and are arranged to face each
other, wherein the rheological fluid is located therebetween such
that in the presence of the applied field, a shear force is set-up
between the surfaces by virtue of the fluid which varies the
stiffness of the structure.
[0015] Alternatively, the structure may include a piston moveable
within the chamber. Preferably the piston is an electromagnet such
that the magnetic field strength may be varied within the chamber.
More preferably, the piston is hollow providing a fluid flow path
therethrough. Thus as the magnetic field strength is increased, the
fluid particles in the piston align. This results in an apparent
increase in viscosity that reduces the ability of the fluid to flow
through the piston. Therefore by increasing the magnetic field,
resistance to flow reduces the flex and hence increases the
stiffness of the structure. The converse is also true. This
vibration control system may be referred to as a resistive flow
active flex system.
[0016] According to a second aspect of the present invention there
is provided a vibration control system, the system comprises a
mounting surface upon which is located a flexible hose, the hose
having a first cross-sectional area filled with a rheological fluid
and ends abutted to the surface.
[0017] The system provides semi-active damping as any flexing of
the mounting surface will create a change in the cross-sectional
area of the hose and cause the hose to act as a pump, while
application of an applied field will cause the fluid to act as a
valve. Consequently, an increase in field increases the fluid
viscosity, the valve makes it more difficult to pump the fluid and
thus more force is required to flex the hose, providing a damping
effect.
[0018] The rheological fluid may be an electrorheological fluid
which undergoes a change in viscosity proportional to a change in
electric field. Advantageously the rheological fluid is a
magnetorheological fluid which undergoes a change in viscosity
proportional to a change in applied magnetic field.
[0019] Preferably the rheological fluid is `Rheonetic Fluid` as
produced by Lord Corporation, USA.
[0020] Preferably a plurality of hoses are located on the surface.
More preferably the hoses are located symmetrically on the
surface.
[0021] According to a third aspect of the present invention there
is provided an adaptive vibration control system, the system
comprising sensing means to determine one or more environmental
characteristics, a signal processor to determine a controlling
response to the characteristics and vibration control means
responsive to the controlling response to counter vibration.
[0022] Preferably the sensing means is at least one sensor. More
preferably the sensing means is a multi-sensor array.
Advantageously the sensor array is a distributed array of PVDF
piezo-sensors.
[0023] Preferably the signal processor identifies characteristic
vibration patterns from the sensors. The signal processor may also
include a control algorithm to identify the patterns. Preferably
also the signal processor includes a feedback loop from the
vibration control means to regulate the response.
[0024] Advantageously, the signal processor is a microprocessor.
More preferably, the microprocessor is a
proportional-differential-integral processor. Advantageously, the
control algorithm is a fuzzy logic control algorithm to provide an
intelligent control unit. Such an intelligent control unit with a
fuzzy logic control algorithm programmed into the microprocessor
may grade the vibration being monitored and control a graded
response from the vibration control means.
[0025] Preferably the vibration control means comprises a vibration
control system according to the first aspect. Preferably also the
vibration control means comprises a vibration control system
according to the second aspect. Advantageously the controlling
response will determine the applied field.
[0026] Alternatively, the vibration control means comprises the
vibration control system of the first aspect in combination with a
direct shear mode semi-active damping system.
[0027] The direct shear mode semi-active damping system may
comprise a fluid filled chamber which is acted upon by a piston to
vary the characteristics of the fluid. More preferably, the fluid
is a magneto-rheological fluid.
[0028] Advantageously, the piston is an electromagnet having a
variable magnetic field strength. Thus in use, movement of the
piston varies the magnetic field strength which in turn influences
the alignment of iron particles in the fluid, the aligned particles
being sheared as the piston moves.
[0029] Advantageously the adaptive vibration control system may be
automatic. Alternatively the adaptive vibration control system may
operate from a switch.
[0030] Preferably also the adaptive vibration control system
includes a power supply located adjacent the system. More
preferably the power supply is driven from vibration experienced by
the structure. The power supply may include piezo material such
that movement of the structure creates an electric signal.
[0031] Further, the adaptive vibration control system may include a
user interface. The user interface may allow a user to provide the
signal processor with data on one or more environmental
characteristics. The user interface may comprise a wire or wireless
connection to a remote device. The remote device may be a handheld
device. More preferably, the remote device is a mobile
PDA/phone.
[0032] According to a fourth aspect of the present invention there
is provided a ski, the ski including a vibration control system
according to the first aspect to vary stiffness in the ski.
[0033] Preferably the vibration control system is arranged fore and
aft on the ski body. Advantageously the vibration control system is
arranged longitudinally on the ski, on either side of a
binding.
[0034] According to a fifth aspect of the present invention there
is provided a ski, the ski including a vibration control system
according to the second aspect to vary damping in the ski.
[0035] Preferably the vibration control system is arranged fore and
aft on the ski body.
[0036] According to a sixth aspect of the present invention there
is provided a ski, the ski including a vibration control system
according to the first and second aspects to vary both stiffness
and damping in the ski.
[0037] Preferably the vibration control systems are arranged fore
and aft on the ski body. Advantageously the vibration control
system according to the first aspect is arranged longitudinally on
the ski, on either side of a binding.
[0038] According to a seventh aspect of the present invention there
is provided a ski, the ski including an adaptive vibration control
system according to the third aspect to provide adaptive control of
vibration in the ski.
[0039] Preferably the sensor arrays are positioned at modal points
on the ski. More preferably the sensor arrays are located at a fore
and aft location in a body of the ski.
[0040] Preferably also the vibration control means are located a
modal points on the ski. More preferably the vibration control
means are located at fore and aft locations on a body of the ski.
Advantageously the vibration control means according to the first
aspect is arranged longitudinally on the ski, on either side of a
binding.
[0041] Preferably the power supply powers the microprocessor and
the variable magnetic field. More preferably the power supply
comprises a layered piezo-ceramic. The piezo-ceramic may be located
on the ski at a position where a skier's boot will rest. Thus the
layered piezo-ceramic is configured at the point of maximum weight
concentration to ensure it flexes as the skier moves. In this
embodiment, power generation comes from the skier's movement over
the ski, rather than the vibrating ski.
[0042] According to an eighth aspect of the present invention there
is provided a chassis for mounting on a ski, the chassis including
a vibration control system to control vibration of the ski in
use.
[0043] By mounting the vibration control system on a chassis, the
ski geometry can be varied as required.
[0044] Embodiments of the present invention will now be described,
by way of example only, with reference to the following drawings in
which:
[0045] FIG. 1 is a schematic diagram of a ski according to an
embodiment of the present invention;
[0046] FIG. 2 to is an exploded view of a portion of FIG. 1
illustrating a vibration control system for varying stiffness
according to an embodiment of the present invention;
[0047] FIG. 3(a) is an illustration of an alternative embodiment of
a vibration control system for varying stiffness and FIG. 3(b)
shows this embodiment mounted on a ski;
[0048] FIG. 4 is an exploded view of a portion of FIG. 1
illustrating a vibration control system for varying damping
according to an embodiment of the present invention;
[0049] FIG. 5(a) is an illustration of an alternative embodiment of
a vibration control system for varying damping and FIG. 5(b) shows
this embodiment mounted on a ski;
[0050] FIG. 6 is a schematic diagram of an adaptive vibration
control system according to an embodiment of the present
invention;
[0051] FIGS. 7(a) and 7(b) are illustrations of an adaptive
vibration control system mounted on a ski, according to an
embodiment of the present invention;
[0052] FIGS. 8(a) and (b) are illustrations of a power supply for
use on a ski according to an embodiment of the present invention;
and
[0053] FIGS. 9(a) and (b) are schematic diagrams of a ski chassis,
according to an embodiment of the present invention, mounted on a
ski.
[0054] Reference is initially made to FIG. 1 of the drawings which
depicts a ski, generally indicated by reference numeral 10,
according to an embodiment of the present invention. Ski 10 has a
conventional composite structure 12 providing a tip 14, tail 16,
upper surface 18 and edges 20a,b. Mounted upon the upper surface
18, towards the edges 20a,b are four symmetrically positioned
damping support bars 24a,b. The bindings (not shown) will be
attached to the ski at the support bars 24a,b. This position will
therefore bear the weight of the skier. Over the damping bars 22
and the support bars 24 are control rails 26a,b. The bars 22,24 and
rails 26 are all arranged longitudinally on the ski 10.
[0055] Between the damping bars 22 and the control rails 26 is
located a rheological fluid 28. Rheological fluids are well known
and operate by increasing the viscosity of the fluid in response to
an applied field. In the embodiment shown the fluid 28 is a
magnetorheological fluid which undergoes a change in viscosity in
response to a changing magnetic field. This arrangement of bars 22,
rails 26 and fluid 28 provides a vibration control system in the
form of an active flex control which can vary stiffness in the ski
10.
[0056] A first embodiment of the flex control system is illustrated
with the aid of FIG. 2. FIG. 2 shows the interface between the
damping bars 22 and the control rails 26. A magnetic field is
applied between the bars 22 and rails 26 in the direction of arrow
A. The magnetic field is applied via coils 30 (only one shown in
FIG. 1) mounted on the rails 26. The consequent increase in
viscosity of fluid 28 creates a shear force in direction BB'. The
control rails 26 mechanically amplify the direct-shear mode and
thus control the stiffness matrix (the inverse of side flex) of the
composite 12 making up the ski 10. The direct-shear mode when
applied reduces the movement of the bars 22 with respect to the
rails 26. Vibration is thus controlled as the resultant change in
stiffness alters the deflection of the ski 10 in response to
impulses. Control can be varied by varying the amount of fluid 28
and the applied field. Thus at a high magnetic field the bars 22,24
and rails 26 will effectively `lock` providing the ski 10 with a
high stiffness. The arrangement shown in FIG. 2 provides active
flex control to the ski 10 when the magnetic field is applied. The
field is switched on via a switch 32 located on the upper surface
18 of the ski 10 or via an adaptive vibration control system,
described hereinafter with reference to FIG. 6.
[0057] In the preferred embodiment small volumes of fluid 28 are
used which require small field strengths so that the ski 10 can be
both lightweight and cheap to produce.
[0058] An alternative embodiment of the active flex control is
shown in FIG. 3. In this arrangement actuators, generally indicated
by reference numeral 50, provide the active flex control by a
resistive flow concept. Each actuator 50, comprises a chamber 52
which is filled with a magnetorheological fluid 54. Within the
chamber 52 is arranged an electromagnetic coil 56, in which passes
a piston or slider head 58. The piston 58 includes a plastic sleeve
60, acting as a plunger. Further the piston has a hollow bore (not
shown). In use the steel piston head 58 acts as an electromagnet
and varies the magnetic field strength within the fluid filled
chamber 52. Fluid 54 flows through the hollow bore. As the magnetic
field strength is increased, the fluid particles in the piston
align in the direction shown by broken line C by virtue of the
magnetic flux path shown by arrow D. This results in an apparent
increase in viscosity that reduces the ability of the fluid 54 to
pass through the piston 58. Therefore, by increasing the magnetic
field, resistance to flow reduces the flex, and hence increases the
stiffness, of the ski to which the actuator is attached. The
stiffness can be decreased by decreasing the magnetic field
strength also. As the ski flexes, resistive flow reduces
displacement of the piston sleeve 60.
[0059] FIG. 3(b) illustrates four active flex actuators 53a-d,
located on a ski 62. The actuators are longitudinally arranged on
the ski, in pairs, symmetrically about the binding position 64.
[0060] As the ski 10, 62 can vary its stiffness as described
hereinbefore, conventional passive-damping techniques would be
insufficient as the damping requirements will need to vary. Ski 10
incorporates a semi-active damping system, best illustrated in FIG.
4, to change the damping level and optimally counteract motion with
a controlled resistive motion. This is achieved by applying the
pressure driven flow mode of operation for controllable fluids.
[0061] Reference is now made to FIG. 4 of the drawings which
illustrates a damping bar 22 as a vibration control system
according to an embodiment of the present invention. The damping
bar 22 has ends 34a,b which abut the upper surface 18 of the ski
10. Each bar 22 is made of a flexible hose. The hose is filled with
fluid 28. The fluid 28 is sealed in the hose. When mounted on the
ski 10, the hose has a uniform cross-section. The hose acts as a
pump when flexed. Flexing creates a change in the cross-sectional
area and the resulting restriction produces a pressure change which
drives the fluid 28. When the magnetic field, described
hereinbefore, is applied the viscosity of the fluid 28 increases.
The fluid then acts like a valve making it more difficult to pump
the fluid and therefore requiring more force to flex the hose. This
damping arrangement of fluid filled hoses or fibres can be arranged
along the length of the ski 10 to act against vibration.
[0062] Like the active flex control, the semi-active damping system
can be constructed using small amounts of fluid 28 placed in fibres
to reduce weight and cost of the ski 10.
[0063] A further embodiment of a semi-active damping system is
shown in FIG. 5. The system comprises a damper, generally indicated
by reference numeral 70, which acts in the direct shear mode of
magnetorheological fluid to achieve semi-active damping. Damper 70
comprises magnetorheological fluid 72 filled chamber 74. A piston
76 is arranged within the chamber onto which is located an
electromagnetic coil 78. The piston 76 thus acts as an
electromagnet. The piston has a plastic sleeve 80 and is arranged
within a steel sleeve 82. In use, vibration causes the plastic
sleeve 80, to act as a plunger and force the piston 76 to move
inside the sleeve 82. This increases the magnetic field strength in
the magnetic flux path E and causes iron particles in the fluid 72
to align, F, between the ends 84,86 of the piston 76 and the steel
sleeve 82. The aligned particles are sheared as the piston 76
moves. As the magnetic field increases the damping is
increased.
[0064] Reference is now made to FIG. 5(b) which illustrates the
dampers 70 mounted on a ski 90, in pairs. Fore-body damping occurs
at a position 92 near the tip of the ski 90 while aft-body damping
occurs at a position 94 towards the tail of the ski. Positions 92
and 94 are selected to be those regions of significant vibration on
the ski when in use.
[0065] It will be appreciated by those skilled in the art that the
active flex systems and the semi-active damping systems described
hereinbefore can be used independently on a ski.
[0066] Reference is now made to FIG. 6 of the drawings which
illustrates an automatic adaptive vibration control system for ski
10,62,90. A multi-sensor array 36 is located on a ski. The array 36
is made up of a distributed array of PVDF piezo-sensors. Though
only one location for the array 36 is shown in FIG. 1 for ski 10,
it will be appreciated that the sensors could be located across the
entire structure of a ski 10. In a preferred embodiment the sensors
are concentrated about regions of significant vibration i.e. modal
points on the ski. The typical modal points are located in the fore
and aft body structure of the ski, see FIG. 7(b) to be described
hereinafter.
[0067] Signals from the sensors in the array 36 are input to a
signal processing unit 38 which, using a stored algorithm,
identifies a characteristic vibration pattern dependent on the
environmental conditions and the handling of the ski 10. Unit 38
then determines a response proportional to the amplitude of the
vibration which is transmitted to the coils 30 controlling the
magnetic field strength. Thus the stiffness and damping can be
controlled as described hereinbefore. A feedback loop 40 is also
provided to enable the amount of actuator response to be
regulated.
[0068] Reference is now made to FIG. 7 of the drawings which
illustrates a ski, generally indicated by reference numeral 100,
including an adaptive vibration control system to provide active
flex control and semi-active damping, according to an embodiment of
the present invention. Ski 100 includes a matrix structure into
which is arranged a pattern of adaptive flex actuators 110a-d and
semi-active dampers 120a-d. This may be termed a smart material
130. The smart material 130 is arranged longitudinally on the ski
100. At a point near the tip 112 is located a fore-body control
point (FCP) 114 and at a point near the tail 116 is located an
aft-body control point (ACP) 118.
[0069] Further on the ski 100 are arranged arrays of vibration
sensors 140a-e. These sensors 140a-e are PVDF piezo-sensors which
convert vibrational movement to an electrical signal indicative of
the amount of vibration experienced. These sensors 140a-e are
positioned at positions, or modal points, where significant
vibration is experienced by the ski 100. Thus they are located fore
and aft on the ski towards each side.
[0070] Located centrally on the ski 100, at the position of the
binding is an intelligent control unit 150. Control unit 150 is an
advanced version of the adaptive control unit illustrated in FIG.
6. The unit includes a proportional-differential-integral (PID)
microprocessor 152 on a microchip as the signal processor. A fuzzy
logic control algorithm is programmed into the microprocessor 152,
to grade the vibration being monitored by sensors 140 and control a
graded response from the controls 110,120. This ensures the system
operates within bandwidths of vibration and does not become
unstable.
[0071] Also included with the intelligent control unit 150 is a
control panel 152 which allows a user to input values
representative of environmental characteristics into the
microprocessor 152. For instance these may be the skiers weight,
style, ability and snow condition. The control panel 152 may also
include a main switch to enable and disable the unit 150. It will
be understood that the control panel 152 may be remote from the
unit 150. A cable to a switch located with the skier may, for
example, be used. Alternatively the control panel may be a mobile
telephone or a PDA (Personal Digital Assistant), providing the user
with a wireless connection to the unit 150.
[0072] FIG. 6 also shows a power supply 42 used to drive the
stiffness and damping vibration control systems. A similar power
supply will be incorporated in the intelligent control unit 150
also. In the embodiments described hereinbefore this supply 40
would be the coils. Alternatively electromagnets could be used. The
power supply 42 could also be replaced by a system such as
piezoelectrics which are powered from the movement of the skis.
FIG. 8 illustrates such a power generation system.
[0073] Referring initially to FIG. 8(a), mounted on a ski 160, at a
point between the binding toe and heel piece, is a layered
piezo-ceramic (PZT) 162. The layers 164,166,168 are parallel to an
upper surface 170 of the ski 160 as illustrated in FIG. 8(b).
Between the PZT 162 and the surface 170 is a raised section 172.
The raised section 172 provides a small contact area with the PZT
162 compared to a large contact area on the ski 160. In use, a
skiers weight is concentrated on the ski at the point shown by
arrow G. This is directly on the PZT 162 and provides a point
loading to increase strain through the layers of the PZT 162 to
increase the output from the PZT 162 as the power supply 40. Thus
the power is generated by the skiers movement on the ski.
[0074] A further embodiment of the present invention is shown in
FIG. 9. FIG. 9 illustrates a ski chassis, generally indicated by
reference numeral 180, which includes an adaptive vibration control
system according to the present invention. The chassis 180 can be
mounted on a ski 182 at the binding 184. Indeed the binding 184 may
be mounted upon the chassis 180 via a binding mount provided as
part of the chassis 180. The chassis comprises flex actuators
186,188 located at either side of the binding mount 184,
semi-active dampers 190,192 at modal points towards the ends of the
chassis, a power supply mounted centrally with the control unit.
These components are all as described hereinbefore with reference
to FIG. 1 to 8. By locating the components on a chassis, this
raised superstructure moves the rheological fluid away from the
ski's neutral axis and thus mechanically amplifies any change
occurring in the control elements. A further advantage to using a
chassis is that it raises the binding off the ski and increases the
swing weight or torque to put the ski onto its edge. This is
regulated in competition and also has health implications in terms
of knee damage. In using a chassis this can be designed to conform
with regulations. A yet further advantage of incorporating a
vibration control system on a chassis is that a single chassis can
be interchanged between skis of varying geometry as required.
[0075] The principal advantage of the present invention is that it
provides a vibration control system which, when incorporated into a
ski, allows control of vibration and improves handling and skier
performance by adapting physical properties of the ski.
[0076] A further advantage of the present invention is that it
allows a single ski to be used for a variety of environmental
conditions by varying the stiffness of the ski.
[0077] A yet further advantage of the present invention is that it
provides a simple pump for semi-active damping control through use
of a fluid filled flexed hose.
[0078] It will be appreciated by those skilled in the art that
various modifications may be made to the invention hereindescribed
without departing from the scope thereof. For example, while the
embodiment shown is a ski, any object subjected to vibration over a
wide bandwidth could be fitted with the vibration control system of
the present invention. Additionally, the number of damping bars and
shear-mode interfaces could be varied on an object.
* * * * *