[0001] The present invention relates to ski bindings and more particularly to a method and
apparatus for initiating release within the bindings in order to prevent or minimize
injuries, especially in the lower extremities of the skier.
[0002] In the past, a wide variety of ski bindings has been developed and made commercially
available in view of the greatly increasing popularity of snow skiing. Along with
the increase in popularity and practice of snow skiing, there has been a corresponding
increase in injuries, especially in the lower extremities of the skiers. Generally,
ski injuries have tended to concentrate in the tibia, in the form of mid-length fracture,
as well as in the ankle and knee.
[0003] There has been a substantial effort to improve all types of ski equipment for minimizing
such injuries including improvements in ski boots and skis themselves as well as in
ski bindings. However, much effort directed toward the elimination or prevention of
such injuries has concerned the binding since it has been found that release of the
skier from the ski is one of the most effective means of protecting the skier during
injury-provoking situations such as falls and the like.
[0004] Until approximately 1973, commercially available ski bindings were designed and adjusted
for mechanically initiating release by limiting the magnitude of loading between the
boot and ski. This design approach is generally based upon the theory that deformations,
particularly in components of lower extremities of the skier, are directly related
to loading magnitude. However, it came to be realized that bindings designed according
to this theory did not satisfy the dual requirements of safety and retention. In this
connection, safety requires that the binding release the skier in sufficient time
to prevent predictable injury. However, because of a failure to accurately predict
such injury-provoking situations, bindings adjusted for such safety considerations
have often tended to be subject to premature release during skiing, even under conditions
appearing unlikely to produce injury. On the other hand, with bindings being adjusted
to assure retention under different skiing conditions, there has been found to be
a greater tendency for injury.
[0005] Accordingly, there has developed another theory for injury prevention during skiing
based on the recognition of a dynamic system of the lower skier extremities as a biomechanical
system consisting of inertia, stiffness and dissipative elements. It was hypothesized
that under loading conditions typical in skiing, such a system is excited dynamically
with no direct relationship between applied loading magnitude and deformation. This
hypothesis was confirmed by actual tests and measurements indicating that the frequency
content of lower extremity loading was sufficient to excite the dynamic model. In
order to explain the inability of ski bindings to simultaneously satisfy safety and
retention requirements, it was further hypothesized that binding release levels were
not sufficiently sensitive to load duration. Accordingly, further experimental studies
were conducted for binding release levels under shock loading in order to confirm
this hypothesis, whereupon a general conclusion has developed that such a dynamic
system theory of lower extremity injury is able to simultaneously satisfy both release
and retention requirements.
[0006] However, it has been found that ski bindings presently available do not take advantage
of this theory or otherwise fail to include suitable techniques or apparatus for initiating
release within a binding in order to realize the potential advantages of such a dynamic
system.
[0007] It is therefore an object of the present invention to provide a method and apparatus
for initiating release within ski bindings based on the concept of such a dynamic
system for the lower extremities of a skier. In general, it is possible to base decisions
for initiating release in such a binding on either direct measurement of deformation
in lower extremity components of the skier or to calculate such deformations from
measurements of other physical variables such as loading, velocity or acceleration.
The second possibility has been considered more practical within the present invention
and, accordingly, the method and apparatus of the present invention for initiating
release is based upon the measurement of loading between the ski boot and ski.
[0008] More particularly, it is an object of the present invention to provide a method and
apparatus for initiating release wherein deformation in lower extremity components
of the skier are calculated using a suitable biomechanical model including associated
equations for predicting proximity of injury in one or more components of the skier's
lower extremity under one or more types of skiing conditions.
[0009] It is a related object of the invention to provide computer means which are programmed
with information according to the selected biomechanical model and associated equations,
the method and apparatus for initiating release according to the present invention
further contemplating the measurement of stresses developed between the ski boot and
ski in order to initiate representative signals which are also applied to the computer
means, the computer then being operable for receiving the measured stresses in the
form of electrical signals and driving or exciting the biomechanical model equations
to computer the release variables for properly initiating release to limit injury
to the skier, particularly lower extremity injuries.
[0010] More specifically, it is an object of the present invention to provide strain gage
means or dynamometer means within the binding for producing an electrical signal corresponding
to a predetermined type of actual stress formed by interaction between the ski boot
and ski and communicating that signal to the computer means for determining when the
stresses developed between the boot and the ski are such that loads acting upon the
lower extremity of the skier may tend to be injurious in order to thereupon generate
a release signal for initiating release of the binding.
[0011] It is yet another object of the invention to provide releasable binding means in
a ski binding for rigidly engaging the boot, the binding including dynamometer means
for measuring stress as developed across the substantially rigid binding between the
boot and ski, computer means being responsive to the dynamometer means in order to
determine when the measured stresses may tend to produce injury in order to thereupon
generate a signal for initiating release of the binding. More specifically, the binding
referred to above preferably contemplates that the releasable binding means be centered
about a point located generally along the lower extremity axis of the skier.
[0012] Yet another object of the invention is to provide a ski binding including an integrally
combined dynamometer/releasable binding element adapted for mounting upon the ski
and including dynamometer means for producing a signal representative of a predetermined
type of stress developed within the binding as well as including releasable binding
means for rigidly engaging the ski boot while being responsive to release actuating
means controlled by computer means adapted for processing information from the dynamometer
signals and comparing the processed result with preprogrammed data selected to establish
predetermined conditions for minimizing or preventing lower extremity ski injuries.
[0013] Additional objects and advantages of the invention are made apparent in the following
description having reference to the accompanying drawings.
Figures 1A and 1B represent different modes of release considered in connection with
a single biomechanical model employed for formulation of equations to be used in a
method and apparatus for initiating release in a ski binding according to the present invention;
Figure 2 is a schematic representation of a control circuit adapted for response to
measured stresses in a ski binding and for preprogramming by data and equations from
a biochemical model such as that of Figures 1A and lB in order to initiate release
within a ski binding;
Figure 3A and 3B are similarly different representations for another biomechanical
model similarly employed for formulation of equations to initiate release in a ski
binding according to the present invention;
Figures 4A and 4B are further representations of a dynamic system developed within
the biomechanical models of Figures 3A and 3B;
Figure 5 is a schematic representation of another control circuit adapted for programming
by biomechanical model equations such as for the model illustrated in Figures 3A and
3B in order to initiate a release actuating signal for a ski binding according to
the present invention;
Figure 6 is a similar schematic representation of yet another control circuit including
digital components rather than analog components as used in the circuits of Figures
2 and 5;
Figure 7 is a representation of a ski binding constructed in accordance with the present
invention;
Figure 8 is a schematic representation of a hydraulic unit for actuating and releasing
engagement in a ski binding such as that of Figure 7;
Figure 9 is a multiple representation of reverse surfaces of a single structural dynamometer
or strain gage element;
Figure 10 is a representation, with parts in section, of another embodiment of a ski
binding constructed according to the present invention;
Figure 11 is similarly a representation of a combined dynamometer/releasable binding
element within the ski binding of Figure 10;
Figures 12 and 13 are both representations of the arrangement of strain gages on different
portions of the dynamometer of Figures 10 and 11;
Figure 14 is a plan view, partially broken away, of yet another embodiment of a ski
release binding according to the principles of the present invention;
Figure 15 is a cross-sectional view take along line XV-XV of Figure 14;
Figure 16 is a cross-sectional view taken along line XVI-XVI of Figure 14; and
Figure 17 shows representations of the arrangement of strain gages shown in phantom
in Figure 14.
[0014] within the following description, the method and apparatus for initiating release
in a ski binding according to the present invention is defined by description of various
concepts and components illustrated by the respective drawings. The description is
organized in the following order.
1. First Biomechanical Model
2. First Analog Control Circuit
3. Second Biomechanical Model
4. Second Second Analog Control Circuit
5. Digital Control Circuit
6. First Ski Binding Equipment
7. Second Ski Binding Embodiment
8. Third Ski Binding Embodiment
1. FIRST BIOMECHANICAL MODEL
[0015] One aspect of the present invention relates to the use of computer means for regulating
release of a ski binding according to equations formulated by use of a biomechanical
model for simulating deformations particularly in the lower extremities of a skier.
In this connection, the invention relates to such a dynamic system or biomechanical
model which is used to formulate equations for establishing a release criterion to
minimize or prevent lower extremity injury of one or more types. For example, both
of the specific biomechanical models described in detail below in connection with
the present invention specifically contemplate the prevention of injury in the tibia,
such injury occurring most likely as a break generally at mid-length.
[0016] It will be apparent from the following description that a variation of the biomechanical
model could also be employed for establishing release criteria in order to minimize
or prevent injury in other portions of the skier's leg. In this regard, two other
locations which are particularly susceptible to injury are the ankle and the knee
and it will be obvious that similar equations could be formulated from a similar dynamic
system or biomechanical model in order to assess injury proximity. With equations
available for injuries in various portions of the skier's leg, including for example
the knee, tibia and ankle, any combination of those equations could be applied to
a computer in order to initiate binding release in the event that injurious conditions
are realized.
[0017] In the first biomechanical model contemplated by the present invention, emphasis
is placed upon preventing breakage in the tibia as noted above and accordingly, both
the ankle and knee are assumed to be rigid at least in comparison with the hip. The
hip is assumed to be formed by combined factors of yielding stiffness labeled for
use in associated equations as K
H' the other factorial components of the model being set forth below in connection with
the equation derived from this model. The hip in the biomechanical model is represented
as a spring and a damping factor shown as a capacitive element labeled C
H.
[0018] In any event, the first biomechanical model represents the leg of a skier as a single
degree-of-freedom, second order linear oscillator while assuming that damping, inertia
and stiffness factors for the leg remain constant. With inertia and damping.contributions
being assumed negligible, loading in the leg of the first biomechanical model is generally
determined only by stiffness (K
H) times displacement (0). However, with stiffness also being assumed constant in this
model, it then becomes necessary to solve resulting equations only for displacement
data which may be accomplished in a controller circuit comprising analog or digital
computer as described in greater detail below.
[0019] Mathematical treatment of the first biomechanical model in order to formulate an
equation or equations for application to the controller circuit.or computer in order
to define a latent response of the model is described immediately below. Before commencing
with development of the equations, it is further noted that the first biomechanical
model includes the additional assumptions that the binding for securing the skier's
boot to the ski is preferably centered along the axis of the skier's leg with the
binding forming a rigid connection between the boot and ski. Further, it has been
found from data obtained by study of the biomechanical model that the emphasis on
the midpoint of the tibia as the most probable location for breakage is not entirely
accurate but is believed valid for the purposes of equations set forth below.
[0020] The first biomechanical model referred to above and described in detail below is
pictorially represented in Figure lA which relates to medial-lateral rotation of the
lower extremities of the skier about a vertical axis (see the a axis of Figure 3A)
for establishing a release criterion serving to initiate release of the binding and
Figure 1B which relates to flexion about a horizontal axis perpendicular to the ski
(see the Y axis of Figure 3A) for establishing another release criterion for initiating
release in the binding. The medial-lateral rotation of the first biomechanical model
as illustrated at 10 in Figure lA is based on the assumption set forth above, with
a flexible hip joint 11 and rigid knee joint 12, tibia 13 and ankle joint of the skier
between the tibia and rigid ankle joint 14 adjacent the boot 15, the hip 11 being
formed by yielding stiffness components represented by a spring 16 indicated as K
H in the equations and a viscous damping factor represented by a capacitive element
17 and indicated as D
H in the equations. Similarly, the flexion mode of the first biomechanical model as
illustrated at 10' in Figure 1B is based on similar assumptions, a similar spring
18 and capacitive element 19 form the ankle joint 14', the hip joint 11' being rigid.
The other factors are considered in both of the modes of the first biomechanical model
in Figures 1A and 1B and are set forth in the following table of nomenclature for
the first biomechanical model.
[0022] A method for devising a release decision technique may consist of the four following
steps:
a) Selection of specific injuries for prevention.
b) Identification of injury mechanisms.
c) Development of a biomechanical model which permits accurate assessment of injury
proximity.
d) Quantification of model parameters.
[0023] Commercial mechanical bindings have been, and commonly still are, designed and adjusted
to prevent tibia fractures, both spiral and boot-top types of tibia injuries as well.
Based on tibia fracture research which is not set forth herein, it appears that a
lower boundary failure criterion is simply the quasi-static failure load. The upper
boundary failure criterion includes viscoelastic strengthening and any muscle support.
To err conservatively, the failure measure used here is the quasi-static fracture
strength.
[0024] First approximation dynamic system models for deriving release criteria to protect
against tibia fracture are shown in Figure 1, based on a number of assumptions including
the following:
a) Joint stiffness is linear, constant, and uncoupled.
b) Joint damping is viscous and constant.
c) Model response in medial-lateral rotation and flexion may be calculated independently.
d) Inertias are constant.
e) The ankle and knee joints are rigid in medial-lateral rotation.
f) Bones are rigid.
[0025] Under these assumptions, the medial-lateral rotation model inertia I
zz (See Figure lA) becomes
where the superscripts (1), (2), (3) and (4) denote the moments of inertia of the
thigh, shank, foot, and boot, respectively, about the tibial axis. The stiffness K
H and damping C
H are properties solely of the hip joint. The inertia I
yy in the flexion model is
where the superscripts (3) and (4) denote moments of inertia of the foot and boot,
respectively, about the ankle joint flexion axis. Stiffness K
AB and damping C
AB are combined properties of the ankle- boot system.
[0026] To satisfy the lower boundary failure criterion, the binding should release when
the model dynamic shank loading equals the quasi-static tibia fracture load. To compute
the dynamic shank loading in medial-lateral rotation, the equation of motion is
Assuming that
and that
then the loading M
zs carried by the shank is given approximately by
The failure criterion demands that
where M
z crit is the quasi-static tibia fracture strength in torsion. Accordingly, the medial-lateral
model response,
is the release criterion for indicating injury proximity.
[0027] Similarly, the equation of motion in flexion (see Figure 1B) is
Neglecting the contribution of the damping term, the shank loading My
s becomes
Since the failure criterion in flexion requires that
where M
y crit is the quasi-static tibia fracture strength in bending, the model response ø
c- M
y crit
KAB is the release criterion similarly indicating injury proximity as in the medial-lateral
analysis of the model.
[0028] The release variables 9 and ø of the above equations, particularly equation (1-6)
for medial-lateral model response and equation (1-9) for flexion response, may be
computed using generally conventional computer means with measured stress data obtained
from the binding dynamometer as the biomechanical model input. The manner in which
such data is obtained from the binding is described in greater detail below wherein
different sets of strain gages are employed for measuring actual stresses relating
to medial-lateral rotation and for flexion.
2. FIRST ANALOG CONTROL CIRCUIT
[0029] Typical analog computer means are illustrated in Figure 2 for driving the biomechanical
model equations with the loads obtained from the strain gage means and computing the
biomechanical model-derived release variable established by the equations set forth
above, as indicated by appropriate symbols in Figure 2. Referring now to Figure 2,
a control circuit generally indicted at 22 comprises a conventional power source component
24 including batteries 26 for generating full range voltage +V
B and -VB for application where indicated throughout the remainder of the control circuit.
In addition, a first regulator section 28 produces stepped-down voltages +V
S and -V which are also applied throughout the control circuit 22 as indicated. Another
regulator section 30 generates further reduced voltage levels for direct application
to both a flexion moment Wheatstone bridge assembly 34 and a torsional Wheatstone
bridge assembly 32. An output signal from each of the Wheatstone bridge assemblies
32 and 34 is amplified by a signal conditioning amplifier 36 or 38 and applied to
analog computer means 40 or 42.
[0030] The torsional analog computer means 40 is preprogrammed with model data including
equation (1-6) while the flexion analog computer means 42 is also preprogrammed with
data from the biomechanical model of Figures 1A and 1B including equation (1-9). Accordingly,
the torsional analog computer means 40 operates to generate a release signal in an
output line 44 when the stresses measured by one of the Wheatstone bridge assemblies
of strain gages causes the release variable to exceed the release criterion established
by the biomechanical model of Figure l
A. Similarly, the flexion analog computer means 42 serves to generate a release signal
in an output line 46 when the flexion moment My(t) measured by the strain gages in
the Wheatstone bridge assembly 34 causes the release variable to exceed the release
criterion derived from the biomechanical model of Figure 1B and the related equations.
[0031] The output line 44 from the torsional analog computer means 40 feeds two comparators
48 and 50, one of which is adapted to switch to a high mode when the absolute output
value of the computer means 40 exceeds a preset voltage level corresponding to the
release criterion referred to above. This of course corresponds with the output signal
discussed immediately above. The output line 46 also feeds two separate comparators
52 and 54 which function similarly as the comparators 48 and 50 when the absolute
output value for the flexion computer means 42 exceeds a predetermined voltage level
corresponding to the release criterion for flexion. The analog computer circuits 40
and 42 are adjusted to produce equal release output voltages in the output lines 44
and 46. The four comparators 48-54 are preferably contained in a single integrated
circuit 56 which may be programmed separately from the computer means 40 and 42 if
desired. The gate of a silicon controlled rectifier or SCR 58 is connected to the
outputs of all four comparators. Accordingly, when any of the comparators switches
high, the SCR conducts to generate a release signal in a line 60. As illustrated in
Figure 2, the line 60 is interconnected with a solenoid 62 which serves as a preferred
means for initiating release within a ski binding as will be described in greater
detail below.
[0032] The first biomechanical model and the associated controls of Figure 2 illustrate
the possibility of initiating binding release in response to more than one mode of
stress. As was indicated above, the first biomechanical model of Figures lA and lB
was responsive to both flexion and torsional modes of stress. The association of the
biomechanical model of Figures 1A and 1B with the control circuit of Figure 2 illustrates
the application of data from the model including equations developed in connection
therewith to computer means within the control circuit for generating a release signal
when the release variable exceeds the release criterion.
3. SECOND BIOMECHANICAL MODEL
[0033] A second biomechanical model is also adapted for specifically computing tibial loading.
As in the first biomechanical model of Figures 1A and 1B, the second biomechanical
model may also be adapted or expanded to be responsive to stresses in other parts
of the model, for example in the ankle and knee in particular. However, even other
injury modes could be separately emphasized in the model for initiating a release
signal in suitable computer means for preventing another selected type of injury.
[0034] In any event, the second biomechanical model is specifically directed only toward
torsional stress in the tibia rather than both flexion stress and torsional stress
as with the first biomechanical model. However, the second biomechanical model includes
a first variation indicated at 110 in Figure 3A and a second variation indicated at
110' in Figure 3B for respectively assessing tibial loading in two different types
of situations, namely, during normal cruising skiing when the skier is moving in a
generally stable configuration and during falls when the skier tends to be unstable
and to have his weight concentrated on a single ski. Further in connection with the
second biomechanical model of Figures 3A and 3B, a more detailed model of one of the
lower skier extremities of legs is represented in Figures 4A and 4B. Referring initially
to Figure 4A, the skier's leg is represented with a single moveable joint at the hip,
the knee and ankle being fixed or rigid, the other components of the leg and loading
components applied thereto being self-apparent in connection with the nomenclature
for the second biomechanical model as set forth below. Referring also to Figure 4B,
the leg is merely shown in a free body diagram of inertias in order to better represent
the basis for the following equations developed in connection with the second biomechanical
model.
[0035] Initially, the nomenclature of terms employed in connection with the equations developed
for the second biomechanical model of Figures 3A and 3B are set forth in the following
Table.
[0037] The equations corresponding to the second biomechanical model of Figures 3A and 3B
were developed in a generally similar manner as the equations relating to the biomechanical
model of Figures lA and 1B. However, further research has indicated that the failure
analysis in torsion and bending may be treated independently. Accordingly, unlike
the first biomechanical model, the equations for the second biomechanical model deal
only with torsion stress. However, it will be immediately apparent that bending stress
may also be taken into account for the second model under generally similar parameters
as set forth below for torsion stress. In the second biomechanical model, the lower
boundary of acceptable applied loads is the quasi-static fracture level as with the
first biomechanical model. Following the conservative design approach, the failure
measure used herein is the quasi-static fracture strength.
[0038] It is also important to formulate the second biomechanical model for accurate calculation
of impending injury. Careful consideration of the skiing process leads to the observation
that different biomechanical models are appropriate for controlled skiing and twisting
type falls. To illustrate this point, consider Figures 3A and 3B which depict degenerate
three degree-of-freedom models for the skier-ski system. The three inertias in each
model are the torso inertia
and the leg inertias I
ZZ. The stiffness K and dissipative element C
H are properties of the hip joint. The principal difference between the two models is
that during controlled skiing (Figure 3A), the skier's torso is spatially fixed about
the z axis, whereas during falls, for example (Figure 3B), the ski is spatially fixed
about the z axis. Even though the majority of the skier's weight is then on one ski,
the spatial fixation in controlled skiing occurs because the unweighted ski is used
for balance purposes. Accordingly, torsional shock loads measured between the boot
and ski tend to excite the leg system exclusive of the torso. During twisting type
falls, on the other hand, all the skier's weight is initially on one ski and the torso
rotates relative to the fixed ski. In falls, it is the torso motion relative to the
ski that loads the leg system.
[0039] Different equations describe the motion of each system in Figures 3A and 3B. Assuming
that a dynamometer with stiffness K
D measures the torsion loading between boot and ski, then the equations of motion for
the ski-leg system in Figure 1A become
where I is the ski moment of inertia about the zz tibia axis, T(t) is the torque between
the snow and ski, and θ
1 and θ
2 are absolute rotations of the ski and leg, respectively. Neglecting the contribution
of the unweighted leg in Figure 3B, the equations of motion for the fixed ski system
are
where θ
3 is the absolute torso rotation. Because the ski is fixed and the dynamometer is stiff,
the leg rotation θ
2 will be quite small so that 9
2, θ
2 and 9
2 all approach zero. Equations (2-3) and (2-4) reduce to
[0040] The loading carried by the tibia depends on which biomechanical model is operative.
During falls, the tibia loading M
zs/2 is indicated directly by
where M (t) is the measured dynamometer load. During stable skiing, however, the tibia
loading has a more complex relationship to the dynamometer load. The leg moment of
inertia I
ZZ is given by
where the superscripts (1), (2), (3) and (4) denote the moments of inertia of the
thigh, shank, foot, and ski boot, respectively. From Figures 4A and 4B, the dynamic
tibia loading M
zs/2 at the center of the shank is given by either
or
From Equation (2-8), it is apparent that only when
does the dynamometer load accurately reflect the tibia load. This result is expected
because Equation (2-10) is essentially the criterion for quasi-static loading. In
controlled skiing, Equation (2-10) is not generally valid and Equation (2-8) or (2-9)
must serve for injury proximity calculation if the retention requirement is to be
satisfied
[0041] The use of two different equations for tibia loading depending on the skiing situation
is potentially enigmatic for the binding design problem. If the dynamometer load is
the only measured variable, then the binding cannot differentiate between the loads
of falling and the loads of controlled skiing. This problem may be reconciled only
if the loads of falling satisfy the condition of Equation (2-10). Previous work has
shown that the loads of falling do, in fact, satisfy Equation (2-10). Accordingly,
the loads of falling are quasi-static and Equation (2-8) or (2-9) accurately reflects
model tibia loading in both controlled skiing and falls.
[0042] In pure medial-lateral or torsion rotation, the most obvious discretized dynamic
system model for the lower extremity consists of three degrees-of-freedom with the
boot-foot, shank, and thigh as the three inertias. To facilitate designing and building
of a controller which embodies the injury prevention technique, it is desirable to
reduce the model complexity. Model complexity is reduced by assuming the second model
to be a single degree-of-freedom model with the ankle and knee joints assumed rigid,
the ankle joint being the softer of the two. However, modern plastic ski boots offer
significant support to the ankle in medial-lateral rotation and the rigid assumption
is reasonable. Under these assumptions, the model reduces to that shown in Figures
4A and 4B. Accordingly, either Equation (2-8) or (2-9) may be used to compute the
release variable M
zs/2. M
zs/2 =M
z crit is the release criterion.
[0043] The data from the second biomechanical model of Figures 3A, 3B and 4A, 4B as well
as in the equations set forth above may be applied to computer means of a control
circuit for a binding release mechanism in generally the same manner described above
in connection with the first biomechanical model. Specifically, either Equation (2-8)
or (2-9) may be applied to the computer component of the control circuit. In this
regard, it may be seen that Equation (2-8) requires solution for leg angular acceleration
G
2 which is then subtracted from the measured moment M
z(t). On the other hand, Equation (2-9) requires computation of leg angular acceleration
θ
2, angular velocity of the leg θ
2, and leg medial-lateral rotation, e
2. Accordingly, it is believed that Equation (2-8) offers the simplest approach for
programming of the computer component in the control circuit.
[0044] Two effective control circuits for use with the second biomechanical model of Figure
3 are illustrated respectively in Figures 5 and 6. The control circuit 122 of Figure
5 may be seen as comprising an analog computer generally similar to that of Figure
2. However, internal components of a computer portion of the control circuit 122 as
well as other portions of the circuit have been modified relative to the control circuit
of Figure 2 in order to better adapt it for operation with data from the second biomechanical
model. At the same time, another control circuit is indicated at 122' and includes
a microcomputer adapted for operation in digital form for solving the same differential
equations using numerical intergration techniques. Advantages of microcomputer in
the control circuit 122 of Figure 6 compared to analog type computer as illustrated
in Figures 2 and 5 are described in greater detail below.
4. SECOND ANALOG CONTROL CIRCUIT
[0045] In addition, it may be seen that the control circuit 122 is adapted to receive actual
stress data from a similar arrangement of stress gages formed into a Wheatstone bridge
assembly 124 which is the same as the Wheatstone assembly 32 of Figure 2. In this
connection, it is again noted that the control circuit 122 is adapted for monitoring
only torsional stress which is of course also the function of the Wheatstone bridge
assembly 32 in Figure 2. It will also be discussed in greater detail below that the
actual stress data input for the control circuit 122 of Figure 6 is applied from a
different arrangement of strain gages which will be described below in connection
with yet another embodiment of a ski binding construction in accordance with the present
invention.
[0046] Returning again to Figure 5, it includes a simplified circuit 126 adapted for powering
the entire control system 122 from a single battery 128. Unregulated voltage output
at a nominal ten volts supplied from the battery 128 is applied to a single regulator
section 130 comprising a standard linear integrated circuit device 132 for producing
a regulated voltage output of approximately 5 Volts as indicated at V which is applied
to various portions of the control circuit 122 as indicated throughout Figure 5. In
order to enable operation of the complete control circuit 122 from the single battery
128, a circuit reference voltage of 2 Volts is generated by an operational amplifier
134. The power circuit 126 is similarly connected with the Wheatstone bridge assembly
124 in order to provide excitation similarly as with the Wheatstone bridge assemblies
32 and 34 of Figure 2.
[0047] As with the embodiment of Figure 2, the output from the Wheatstone bridge assembly
124 is applied to a single signal conditioning amplifier 136 which conforms to the
signal conditioning amplifier 36 of Figure 2. The output from the signal conditioning
amplifier 136 is applied to analog computer means 138 comprising four operational
amplifiers 140, 142, 144 and 146 arranged within a single quad amplifier device and
a fifth operational amplifier 148 formed as a second device within the embodiment
of Figure 5. However, the specific arrangement of the operational amplifiers is not
a feature of the present invention. In fact, the computer components for both the
control circuits of Figures 2 and 5 are merely presented as examples of means for
processing data from biomechanical models such as those illustrated in Figures 1A-1B
and Figures 3A-3B. It will be apparent that a number of different computer components
could be employed for achieving this purpose.
[0048] Returning again to Figure 5, each of the operational amplifiers 140-148 includes
programmable bias means for controlling its respective supply current similarly as
in the embodiment of Figure 2. Within the arrangement of the analog computer means
138 for the control circuit 122, low input offset voltage and low input bias current
are not critical specifications for assuring integrating accuracy in the computer
means 138. Integrator voltages are fed back and subtracted for respective operational
amplifiers in order to achieve self-equilibration within the computer means and within
the control circuit 122. Initial offset developed by the strain gages to be discussed
below is removed with the balance potentiometer configuration for the Wheatstone bridge
assembly 124. However, it is to be noted that low input offset voltage drift and input
bias current drift are important to maintain circuit stability under varying temperatures.
The operational amplifiers 140-148 are quite stable in this regard since their input
bias currents are temperature- compensated.
[0049] Finally, within the computer component 138 of the control circuit 122, it may be
seen that the first four operational amplifiers 140-146 of the differential equation
portion of Equation (2-2) function much as the three operational amplifiers function
in the computer means 40 of Figure 2. The fifth operational amplifier 148 performs
the function of subtracting the acceleration e
2 value obtained by the four operational amplifiers 140-146 from the measured applied
load M
z (t) in order to solve Equation (2-8). In this connection, it may be seen that the
output from the signal conditioning amplifier 136 is also applied directly to the
fifth operational amplifier 148.
[0050] The output from the fifth operational amplifer 148 is the release variable which
is compared to the release criterion established by the data from the second biomechanical
model. The signal from the fifth operational amplifier 148 including that data is
applied to a pair of comparators 150 and 152 which function in the same manner as
the comparators 48 and 50 of Figure 2 in order to initiate a release signal by actuating
a silicon controlled rectifier of SCR 154. Within the embodiment of Figure 5, actuation
of the SCR 154 fires a solenoid 156 which for example may be coupled with release
means within a binding. Here again, it is to be noted that the solenoid 156 is merely
one example of release means which may be actuated within. a binding by the control
circuit 122. The function of the solenoid 156 for initiating release is also descibed
in greater detail below in connection with one embodiment of a binding according to
the present invention. In order to reset the circuit, a switch 158 is provided in
connection with the SCR 154 and may be manually operated to momentarily break a current
for the SCR 154 in order to deactuate the solenoid 156.
5. DIGITAL CONTROL CIRCUIT
[0051] Referring now to Figure 6, the control circuit 122' is illustrated in generally schematic
form and described briefly below in order to indicate the possibility of using digital
computer means for solving the equations relating to second biomechanical model of
Figures 3A and 3B similarly as the control circuit 122 of Figure 5. Before describing
the basic components of the control circuit 122', which components in themselves are
generally conventional, it is again noted that the actual stresses applied to the
control circuit 122' are somewhat more complex and are obtained from strain gages
arranged in a ski binding as will be described in greater detail below. In any event,
five Wheatstone bridge assemblies 160, 162, 164, 166 and 168 are illustrated as including
separate strain gage means for monitoring various load components. The specific arrangement
of the various strain gages will also be described in greater detail below. In any
event, the output from the respective Wheatstone bridge assemblies are processed by
separate signal conditioning amplifiers 160A etc., and associated anti-aliasing or
low-pass filters 160F, etc. The signal conditioning amplifiers and filters together
with a sixth signal conditioning amplifier 170A and associated anti-aliasing or low
pass filters 170F form a signal conditioning section 172, the combined output of which
is applied to a digital data acquisition section 174 for converting analog data received
from the Wheatstone bridges into digital form for use within the digital computer
means referred to below.
[0052] The digital data acquisition section 174 includes a time division multiplexer sampling
device 176 interconnected to a sample/hold amplifier 178 and to an analog-to-digital
converter 182 for supplying the measured stress data in digital form. That information
provided as an output from the analog digital converter 182 is applied to a parallel
I/O input assembly 184 in order to apply the data to a computer bus 186 interconnected
with a counter-timer 188, a digital processor 190 and memory means 192. A power source
194 is generally indicated at 194 and is interconnected with the entire control circuit
122' through the digital processor 190.
[0053] The power source 194 may include a number of different batteries for supplying power
to different portions of the control circuit in generally conventional fashion. The
important feature in connection with the power source 194 of the present invention
is its interconnection with the entire control circuit 122' and with the digital processor
190 to permit monitoring of all voltage levels by the digital processor 190. The control
circuit 122' also includes external connector means 196 coupled with the computer
bus 186 for a purpose to be described immediately below.
[0054] The control circuit 122' operates digitally to perform the same function descibed
in greater detail above for the control include circuit 122 of Figure 5 and the control
circuit 22 of Figure 2. Accordingly, the control circuit 122' could also include actuating
means responsive to the computer processor 190 for initiating a release signal to
operate release means within an associated ski binding.
[0055] Numerous advantages are obtainable with use of the microcomputer control circuit
122' of Figure 6. Initially, use of the microcomputer could enhance ski safety even
in comparison with the analog control circuits of Figures 2 and 5. Release accuracy
is improved in the control circuit 122' since the effects of offset voltage, etc.,
being nullified by auto-zeroing of the microcomputer signals or the dynamometer signals
from the Wheatstone bridges 160-168 prior to actual solution of the differential equation
for the second biomechanical model within the circuit. In addition, a microcomputer
may also be employed to check functionality of various components in the circuit such
as the power source, the dynamometer or strain gage signals themselves as well as
the dynamometer channels in order to assure that the binding as well as the control
circuit components are working properly. If not, the microcomputer could provide a
signal as a warning to the skier which would also provide an important safety feature
within the binding assembly. Yet another advantage possible from the use of a microcomputer
is that the differential equations are solved in softward. Accordingly, any refinement
of the control algorithm employed within the processor 190 and/or the differential
equations themselves could be easily implemented within the binding assembly without
the need to resort to hardware changes simply by using external programming means
(not shown) which could be coupled into the processor 190 through the connector 196.
[0056] Still another advantage for the microcomputer control circuit 122' is that the differential
equations applied to the processor 190 would likely vary for different individuals
depending upon the physiological characteristics, skiing ability, skiing conditions
and the like. Here again, different parameters adapted for different individuals or
conditions could be readily entered into the processor 190 again through the external
connector means 196. Generally, analog computer, on the other hand, would require
adjustment in some of its circuit components which would be a relatively complicated
procedure. An external communication link for supplying such data to the connector
196 is generally indicated at 198 and could take a number of forms, the specific nature
of which is not an essential feature of the present invention. For example, the communication
link 198 could comprise a hand-held terminal (not shown) consisting of a keyboard,
monitoring light emitting diodes to indicated conditions within the computer and erasable
programmable read-only memory means containing program and/or instructions to the
processor. However, the communication link 198 could take a number of different forms.
For example, the hand-held terminal might also include connector means for a teletype
or cathode ray terminal in order to permit application of data in that manner. In
that event, the possible use of such external communication link 198 for making adjustments
within the control circuit 122' is believed clearly apparent.
6. FIRST SKI BINDING EMBODIMENT
[0057] As was indicated above, the two biomechanical models and the associated control circuits
described with reference to-Figures 1-6 are subject to sutstantial modification with
features of the two biomechanical models and three control circuits being interchangeable.
Three embodiments of ski bindings particularly adapted for combination with the above-noted
control circuits are described below. A first embodiment of such a ski binding is
illustrated in Figures 7 and 8 with an arrangement of strain gages being illustrated
in Figure 9. Because of the specific configuration of strain gages in Figure 9, the
first ski binding embodiment of Figures 7-9 is adapted for use with the control circuit
of Figure 2. However, it will be apparent from the preceding description and the following
description of the three ski binding embodiments that the ski binding embodiment of
Figures 7-9 could also be employed in combination with a control circuit of the type
in either Figure 5 or Figure 6. Similarly, a second ski binding embodiment is illustrated
in Figures 10 and 11 with an arrangement of strain gages thereupon being illustrated
by Figures 12 and 13. Here again, because of the specific configuration and number
of strain gages, it will be apparent that the embodiment of Figures 10-13 is adapted
for use with the control circuit of Figure 6. However, again, it will be apparent
that upon suitable modification as is made clearly apparent herein, the ski binding
embodiment of Figures 10-13 could also be adapted for use with a control circuit of
the type shown in Figure 2 or in Figure 5. A third ski binding embodiment, illustrated
in Figures 14-16, is adaptable to any of the control circuits when strain gage arrangement
of Figure 17 is considered.
[0058] Referring now to Figures 7 and 8, a ski binding assembly 210 is illustrated for selectively
and releasably securing a ski boot 212 to a ski such as that indicated at 214. The
ski 214 is of a generally standard configuration while the boot 212 is also of conventional
design capable of substantially rigidizing the skier's ankle in accordance with the
assumption made in connection with the two biomechanical models described above.
[0059] The binding assembly 210 includes a binding platform 216 secured to the ski 214 and
a mating mounting plate 218 secured to the bottom of the ski boot 212.
[0060] A releasable clamp unit for securing the mounting plate 218 in place upon the platform
216 is generally indicated at 220 and includes a pair of levers 222 and 224. The clamping
ends 226 of each lever include recesses 228 for mating with similarly shaped projections
230 on the mounting plate 218. Thus, with the mounting plate arranged in abutting
and aligned position upon the binding platform 216, the mounting plate and accordingly
the boot 212 may be secured and placed thereupon by engagement of the clamping ends
226 with the projections 230.
[0061] The levers are operated through a force multiplication linkage 232 by a hydraulic
234 which is also illustrated in Figure 8 and includes manually operated means 236
operable for causing a plunger 238 to act through the force multiplication linkage
232 for engaging the levers 222 and 224 with the mounting plate of the boot. The hydraulic
234 also includes release actuating means preferably in the form of the solenoid indicated
at 62 (also see Figure 2). As indicated in Figure 8, the solenoid 62 may be operated
by a release initiating signal from the control circuit 22 which is also illustrated
in Figure 2.
[0062] These components of the ski binding assembly 210 are described below in greater detail.
Initially, the levers 222 and 224 are commonly pivoted at 242 under a retainer element
241 and bearing-plate 243. The ends of the levers opposite the clamping ends 226 are
respectively and pivotably coupled at 244 and 246 with respective wedging levers 248
and 250 which are pivotably interconnected with each other and with the plunger 238
and 252. The combined length of the two wedging levers 248 and 250 is slightly greater
than the distance between the pivot connections 244 and 246 when the levers are clamped
upon the boot to prevent over-center movement of the wedging lever. Through this arrangement,
as the plunger 238 is shifted rightwardly as viewed in Figure 7, it acts upon the
intermediate lever 208 which in turn acts upon the two wedging levers 248 and 250
in order to apply substantially multiplied force to the levers 222 and 224 in order
to maintain them in rigid clamping engagement with the mounting plate 218 upon the
ski boot 212. The purpose of the intermediate lever which pivots about its base is
to reduce travel of plunger 238.
[0063] Referring now to Figure 8, the hydraulic unit 234 includes a main chamber or cylinder
254 containing a piston 256 arranged for reciprocable movement therein, the plunger
238 penetrating one end wall of the chamber or cylinder 254 for connection with the
piston 256. A reserve chamber or cylinder 258 similarly contains a reciprocable piston
260, a rod 262 for the piston 260 penetrating one end of the reserve chamber 258 for
connection with the manually operated handle 236. The reserve chamber 258 is in communication
with the main chamber 254 by means of a conduit 264 containing a one-way check valve
266 permitting pressurization of the main chamber by manipulation of the lever 236.
The main chamber 254 is also in communication with the reserve chamber 258 by means
of a second conduit 268 which is normally closed by the solenoid 240. However, as
noted above, when the solenoid receives a release initiating signal from the control
circuit 22, it opens in order to release fluid under pressure from the main chamber
254. Immediately thereupon, a spring load acting upon the plunger 238 immediately
causes the plunger 238 and the piston 256 to retract which permits the levers 222
and 224 to completely disengage from the mounting plate 218 upon the ski boot.
[0064] Returning again to the manner of engagement between the boot 212 and the binding
210, both the mounting plate 218 and the platform 216 are especially configured so
that horizontal movement or rotation of the boot is not entirely resisted by the levers
222 and 224. For this purpose, the platform 216 includes a plurality of hemispherical
projections 270 preferably arranged at each corner of that platform 216. Mating hemispherical
recesses 272 are formed upon the corners of the mounting plate 218 in order to receive
the hemispherical projections 270. Because of the mating engagement of the hemispherical
projections 270 within the recesses 272, horizontal movement and more specifically
lateral rotation of the boot tends to produce torsional forces which are applied directly
to the platform 216. In order to even more completely transfer all reaction forces
of the boot 212 to the platform 216, the platform 216 is formed with projections 274
which are in alignment with the projections 230 on the mounting plate 218 and are
adapted for similar engagement with the recesses 228 in the clamping levers 222 and
224. Accordingly, both rotational and bending reaction forces arising in the boot
212 relative to the ski 214 are transferred through the platform 216.
[0065] This arrangement described above for the platform 216 permits the mounting of strain
gages for monitoring both torsional and bending moments upon a structural strain gage
element between the platform 216 and the ski 214. The structural strain gage element
which is thus arranged directly beneath the platform 216 is indicated at 275 in Figure
9. Referring to Figure 9, the structural strain gage element 275 is a simple cylinder
adapted for engagement at its upper end with the platform 216 and at its lower end
with a portion of binding attached to the ski 214. A forwardly facing surface of the
strain gage element or cylinder 275, facing toward the forward tip (not shown) of
the ski 214, as indicated by the arrow X, provides a mounting surface for four strain
gages. A reverse surface of the strain gage element of cylinder is represented by
a reverse representation of the cylinder 275' which is rotated 180° from the position
illustrated for the element or cylinder 275 in order to illustrate the mounting of
four additional strain gages on the opposite surface of the cylinder.
[0066] The strain gages mounted upon the cylinder 275 include four strain gages Gl, G2,
G3 and G4 adapted for monitoring bending moments experienced by the structural strain
gage cylinder 275. Accordingly, strain gages Gl and G2 are arranged in parallel and
vertically extending configurations on the rear surface of the strain gage cylinder
as illustrated at 275'. The other two bending strain gages G3 and G4 are similarly
arranged on the opposite or forward surface of the strain gage cyliner 275. Similarly,
for torsion measurement, two strain gages G5 and G6 are arranged upon the rearward
surface of the strain gage cylinder 275 in perpendicularly overlapping relation with
each other, each of the strain gages being arranged at an angle of 45° from horizontal.
The two remaining strain gages G7 and G8 are similarly disposed upon the forward surface
of the strain gage cylinder 275.
[0067] Referring now also to the control circuit 22 of Figure 2, the strain gages Gl, G2,
G3 and G4 are arranged as indicated within the Wheatstone bridge assembly 34 in order
to supply suitable data regarding actual bending stresses to that portion of the control
circuit 22 concerned with flexion. The other four strain gages G5, G6, G7 and G8 are
similarly arranged within the other Wheatstone bridge assembly 32 which is concerned
with the monitoring of torsional stresses as was also described above in connection
with the control circuit 22. At the same time, a similar arrangement of the strain
gages G5-G8 could also be employed to form the Wheatstone bridge assembly 124 within
the control circuit 122 of Figure 5 which, as was noted above, is concerned only with
torsion moments and not with bending moments.
[0068] In order to briefly summarize the mode of operation for the binding assembly 210
in combination with the control circuit 22 of Figure 2, the boot 212 is rigidly attached
to the ski 214 by the clamping levers 222 and 224 as well as the other related components
of the binding assembly 210. In that configuration , both torsional and bending stresses
arising between the boot and the ski, representative of the first biomechanical model
illustrated in Figures 1A and lB, are monitored by the strain gages of Figure 9 and
supplied to the control circuit 22. Upon the release criterion being satisfied, the
control circuit 22 functions as described above to generate an initiating signal to
the solenoid 62 which appears in each of Figures 2, 7 and 8. Thereupon, the solenoid
62 acts through the hydraulic unit 234 to disengage the clamping levers 222 and 224
from the mounting plate on the ski boot 212. It may be seen that the hemispherical
configuration for the projections 270 and recesses 272 serve to facilitate disengagement
between the ski boot and the-ski upon release in order to further prevent the possibility
of injury to the skier. The skier may reattach the boot 212 to the ski by placing
the mounting plate 218 in alignment with the binding platform 216 and manipulating
the lever 236 in order to pressurize the main chamber 254, thereby causing the plunger
238 to move the clamping levers 222 and 224 into rigid clamping engagement with the
mounting plate 218 on the boot 212.
7. SECOND SKI BINDING EMBODIMENT
[0069] Another embodiment of a ski binding assembly constructed in accordance with the present
invention is generally indicated at 310 in Figure 10 and operates in generally the
same manner as the ski binding assembly 210 of Figure 7. However, the dynamometer
or strain gage component of Figure 7 embodiment as well as its binding components
including the clamping assembly and hydraulic unit are replaced by a combined dynamometer/releasable
binding component 312 which mounts directly upon the ski 314 for binding engagement
with the ski boot 316. The binding assembly 310 also includes a release actuating
means preferably in the form of a pyrotechnic squib 318 which is responsive to a release
actuating signal from the control circuit 122' of Figure 6.
[0070] The combined dynamometer/releasable binding component 312 includes a structural dynamometer
or strain gage element 320 which has slotted portions 322 and 324 arranged at opposite
ends thereof in order to form four half-strain rings upon which strain gages are to
be mounted in accordance with the following description. The dynamometer element 320
may be attached to the ski for example by screws 3.26 which secure the bottom half
of slotted portions 322 and 324 to the ski.
[0071] The integral releasable binding portion of the combined dynamometer/releasable binding
component 312 includes a pair of annular rings 328 and 330 both arranged horizontally
above the ski 314. The ring 328 is integrally formed with the slotted dynamometer
portions 322 and 324 and includes a plurality of radially extending, shaped ports
332 for respectively capturing ball bearings 334. The other ring 330 is attached to
the boot 316, preferably within a recess 336 formed in the sole of the boot, the ring
330 being of annular configuration with a tapered central cavity 338 adapted for nesting
arrangement of the rings 328 and 330 as may be best seen in Figure 10. The tapered
central cavity 338 also includes spherical depressions 340 adapted for detent engagement
with the ball bearings 334 in a manner described in greater detail below. A locking
piston 342 is arranged within the ring 328, the ski binding assembly 310 also including
a spring means 344 arranged for interaction between the boot 316 and the locking piston
342 in order to urge the locking piston downwardly whereupon the ball bearings 334
are forced outwardly into detent engagement with the spherical depressions 340. The
various components in the configuration illustrated in Figure 10, the boot 316 is
then secured rigidly to the ski 314. At the same time, all reaction forces are transmitted
between the boot 316 and the ski 314 through the structural dynamometer or strain
gage element 320. Accordingly, strain gages may be disposed directly upon the structural
dynamometer element 320 in order to monitor those reaction forces.
[0072] Referring also to Figures 12 and 13, four sets of strain gages are arranged at the
four corners of the structural dynamometer element as indicated by the letters A,
B, C and D. At each of those locations, the slotted portions 322 and 324 of the structural
dynamometer element 320 form a vertical wall 346 and an adjacent wall portion arranged
at an angle of 45° to the adjacent wall portion 346. Each of the wall portions arranged
in a 45° inclination are indicated at 348. A combination of five strain gages is arranged
in each of the locations A-D in order to permit a compensated arrangement of the strain
gages within a plurality of Wheatstone bridges such as those indicated at 160-168
in Figure 6.
[0073] The arrangement of the strain gages in the locations A and C is illustrated in Figure
12 while the arrangement of strain gages at the locations B and D is illustrated in
Figure 13. Furthermore, as noted above, each of the slotted portions 322 and 324 includes
a laterally extending slot 350 with a circular opening 352 adjacent each of the strain
gage locations A-D. In the strain gage arrangement for each of the locations A and
B, strain gages A3 and B3 are arranged upon the cylindrical surface of the opening
352 in the alignment indicated respectively in Figures 12 and 13. The strain gage
combinations for each of the locations C and D includes an externally mounted strain
gage C5 or D5 respectively. This arrangement of the strain gages A3, B3 and C5, D5
permits a more balanced or compensated arrangement for the Wheatstone assemblies of
Figure 6 as will be described in greater detail below. The mounting of the numerically
identified strain gages in each assembly are illustrated in Figures 12 and 13. For
the strain gage assemblies A and B, strain gages A4, A6 and B4, B6 are mounted upon
the vertical wall portion 346. In the strain gage assemblies C and D, the strain gages
C4, C5, C6 and D4, D5, D6 are all similarly arranged upon one of the vertical wall
portions 346. In all of the strain gage assemblies A, B, C and D, the first and second
strain gages are mounted upon the inclined wall portions 348. Accordingly, it may
be seen that all of the strain gages in the four assemblies are arranged perpendicular
to the longitudinal axis of the ski. This configuration for the strain gages results
in a compact and rugged dynamometer which is sensitive to all load components between
the ski and boot with the exception of the force component along the longitudinal
axis of the ski. It has been determined experimentally that loading in this direction
is not of particular significance in predicting release for avoiding ski injuries.
[0074] Referring also to Figure 6, the twenty strain gages at locations A, B, C and D are-arranged
in the five Wheatstone Bridges 160-168 in order to supply compensated data to the
control circuit 122' in the manner described above. Upon a release criterion being
satisfied, the control circuit 122' functions in the manner described above to generate
a release initiating signal in an output line 354 which is connected with the pyrotechnic
squib 318. Detonation of the squib 318 immediately forces the locking position 342
upqardly against the spring 344 allowing the ball bearings 334 to move radially inwardly
and thereupon release the boot and outer annular ring 330 from the inner ring 328.
Use of the two nested, annular rings 328 and 330 is of particular advantage within
the binding assembly 310 because it permits movement of the boot in effectively any
direction after release is accomplished. The tapered annular configuration for the
central cavity 338 further contributes to facilitating release between the rings 328
and 330.
[0075] Thereafter, the skier at his option may reactivate the binding 310 by replacing the
squib 318 and engaging the ring 330 on the boot with the ring 328 and at the same
time urging the locking piston 342 downwardly into the locked configuration illustrated
in Figure 10. The openings or ports 332 which hold the ball bearings 334 are of course
shaped in order to prevent escape of the ball bearings even when the boot is separated
from the ski.
[0076] Also referring to Figures 10 and 11, the skier may selectively release the binding
by rotating a lever 360 secured to a shaft 362 extending into the cavity 338 beneath
the piston 342. The inner end of the shaft is formed with a cam surface 364 for shifting
the piston 342 upwardly against the spring 344 to release the binding upon rotation
of the shaft 362 by the lever 360.
[0077] In both the embodiment of Figures 7-9 and the embodiment of Figures 10-13, the thickness
of the binding may be minimized between the ski boot and the ski as may be best seen
in Figures 7 and 10. At the same time, it is again noted that the two ski binding
embodiments may be adapted for use with any of the control circuits illustrated respectively
in Figures 2, 5 and 6.
8. THIRD SKI BINDING EMBODIMENT
[0078] Referring now to Figures 14-16, there are shown a ski binding 410, a ski boot 412
having a boot plate 414, and a ski 416. Ski binding 410 releasably secures ski boot
412 to ski 416.
[0079] Ski binding 410 includes a housing 418, a pair of clamps 420, bias means 422, dynamometer
means 424, and control means 426.
[0080] Housing 418 defines a generally elongated platform 428. Platform 428 has an upper
side 430, a lower side 432, a forward portion 434, a middle portion 436 and a rearward
portion 438. Middle portion 436 has a pair of lateral edges 440.
[0081] Each clamp 420 includes an upper end portion 442 and a lower end portion 444. Housing
418 further includes first mounting means 446.for rotationally mounting each clamp
420 in a facing relationship to a different one of each lateral edge 440. As best
shown in Figure 16, each clamp 420 is rotatable between a first position as illustrated
therein and a second position shown in phantom.
[0082] Upper end portion 442 of each clamp 420 is adapted to secure boot plate 414 to upper
side 430 of elongated platform 428. As best shown in Figure 16, boot plate 414 may
include a rib 448 extending outwardly from the lateral periphery thereof. An upper
surface 450 of rib 448 is angled downwardly from the horizontal plant. Upper end portion
442 of clamp 420 may include a notch 452, dimensioned to engage rib 448. When each
clamp 420 is in the first position, boot plate 414 is secured to upper side 430 of
elongated platform 428. When each clamp 420 is rotated to the second position, boot
plate 414 (as well as ski boot 412) is free to separate from ski binding 410. The
angled upper surface of rib 448 eliminates frictional resistance between rib 448 and
notch 452 when clamp 420 is being rotated to the second position under force of boot
plate 414 urging against each clamp 420.
[0083] Dynamometer means 424 secures forward portion 434 and rearward portion 438 in a spaced
apart relationship to ski 416. As hereinafter described, dynamometer means 424 further
measures dynamic forces induced between elongated platform 428 and ski 416 and develops
a plurality of signals, each of the signals being associated with a measurement of
a different one of components of the dynamic forces.
[0084] The details of control means 426 have been fully described in Figures 1 through 6
herein.
[0085] Bias means 422 includes a generally elongated rod 454, a generally cylindrical member
456, and a pair of roller structures 458.
[0086] Elongated rod 454 has a first end portion 460 and a second end portion 62. Housing
418 further includes second mounting means 464 for longitudinally mounting in a spaced
apart relation first end portion 460 and second end portion 462 underneath middle
portion 436.
[0087] Cylindrical member 456 has an axial bore 466 dimensioned to receive rod 454. Cylindrical
member 456 is mounted in axially slidable engagement on rod 454.
[0088] Each roller structure 458 has an outer end 468 adapted for mounting to lower end
portion 444 of clamp 420 in rotationally slidable engagement, a generally U-shaped
inner end 470 defining a pair of free ends 472, an elongated member 474 connecting
outer end 468 and inner end 470, an axle 476 mounted to free end 472, a roller 478
rotatably mounted on axle 476, and a bias element 480 arranged for normally biasing
roller structure 458 to loosely maintain each clamp 420 in the first position, providing
a sensation of engagement when a user wearing boot 412 steps into binding 410. Axle
476 is arranged generally perpendicular to elongated platform 428. Housing 418 further
includes third mounting means 482 for supporting elongated member 474 in linear slidable
engagement.
[0089] Cylindrical member 456 is positionable between roller 478 of each roller structure
458 defining a locked position for biasing each roller structure 458 to maintain each
clamp 420 in the first position, as best shown in Figures 14 and 16.
[0090] Bias means 422 further includes a solenoid 484 having a plunger 486. Cylindrical
member 456 when in the locked position is positioned proximate plunger 486.
[0091] Control means 426, as described hereinabove, develops a release signal when any component
of the forces measured by dynamometer means 424 exceeds a predetermined limit. Solenoid
484 in response to the release signal projects plunger 486 toward cylindrical member
456. Plunger 486 urges cylindrical member 456 towards one end portion, such as second
end portion 462, of elongated rod 454 defining an unlocked position. Cylindrical member
456 after being displaced from the locked position allows roller structures 458 to
translate inwardly to move each clamp 420 to the second position.
[0092] Dynamometer means 424 includes first strain gage means 488 associated with forward
portion 484 and second strain gage means 490 associated with rearward portion 438.
First and second strain gage means 488 and 490 develop the electrical signals as hereinabove
described in response to the forces developed between elongated platform 428 and ski
416.
[0093] First and second strain gage means 488 and 490 include four half strain rings, shown
herein as A, B, C and D (Figures 14-16). Each half strain ring has thereon four strain
gage elements, strain ring B in Figure 15 being representative thereof showing Bl,
B2, B3 and B4. Referring now also to Figure 17, the inner connections between all
strain gages of strain rings A, B, C and D are shown as bridge circuits which measure
the axial components of force F
x, Fy, and F
z, and the moments about the axial components, M , M , and M . The bridge innerconnections,
as shown in Figure 17, develop the electrical signals to which the control means is
responsive to, as explained hereinabove with reference to Figures 1-6. A different
plate 491 is positionable between each strain ring A, B, C and D and ski 416.
[0094] Returning now to Figures 14-16, ski binding 410 further includes manually operable
locking means 492 for selectively engaging bias means 422 to position clamps 420 in
either the first position or the second position.
[0095] Locking means 492 includes the generally U-shaped harness 494, a generally elongated
rod 496 rotatably connected to harness 494 at one end portion thereof, a handle 498
mounted to another end portion of rod 496, and a bias spring 500. Housing 418 further
includes fourth mounting means 502 for supporting locking means 492 in linear slidable
engagement.
[0096] Harness 494 includes a pair of arcuate fingers 504. Cylindrical member 456 further
includes a reduced diameter portion 506 defining a first and second shoulder 508 and
510. Arcuate fingers 504 are in axially slidable engagement with reduced portion 506
between shoulders 508 and 510. In the locked position as shown in Figure 14, arcuate
fingers 504 are adjacent first shoulder 508. Should solenoid 484 displace cylindrical
member 456 in response to the release signal as hereinabove described, cylindrical
member 422 is axially displaced until arcuate fingers 504 contact second shoulder
510. Depression of handle 498 causes arcuate fingers 504 to push against second shoulder
510 to replace cylindrical member 456 to the locked position of Figure 14. Bias spring
500 will return locking means 492 to its normal position as shown in Figure 14.
[0097] In order to place cylindrical member 456 in the unlocked position by using locking
means 492, handle 498 is rotated until a projection 512 radially extending from rod
496 is alinged with an axial slot 514 of fourth mounting means 502. Bias spring 500
will urge locking means 492 outward, arcuate fingers 504 exerting a pull on first
shoulder 508 to remove cylindrical member 456 from the locked position.
[0098] First mounting means 446 includes two pairs of arms 516 and a plurality of pins 518.
Each pin 518 is mounted generally perpendicular to a different one of each arm 516.
On each pair of arms 516, pins 518 define an axis of rotation for clamp 420. Each
clamp 420 includes an aperture 520 at each end thereof to receive pin 518 in rotationally
slidable engagement.
[0099] Second mounting means 464 includes two pairs of mounting blocks 520, and an elastomeric
bushing 522 associated with each pair of blocks 520. Fasteners 524 secure blocks 520
to housing 418. First and second end portion 460 and 462 are secured within each pair
of blocks 520 by bushings 522. Bushings 522 absorb impact forces when plunger 486
strikes cylindrical member 456 to minimize friction between cylindrical member 456
and rod 454.
[0100] Third mounting means 482 includes a pair of walls 526 extending downwardly from lower
side 432, each wall being adjacent a different lateral edge 440 of middle portion
436. Each wall 526 has a hearing element 528 dimensioned commensurate with elongated
member 474 for minimizing friction therebetween.
[0101] Fourth mounting means 502 includes a wall 530 extending downwardly from an edge 438a
of rearward portion 438, a first tube 532 extending rearwardly of wall 530 and a second
tube 534 extending forwardly of wall 530 and being coaxial with first tube 532. First
tube 530 is dimensioned to receive handle 498 in linear slidable engagement spring
500 being disposed coaxially around rod 496 to exert against handle 498 and wall 530.
Second tube 532 is dimensioned to receive rod 496 and also has axial slot 514 as hereinabove
described.
[0102] It is also noted again that numerous modifications and variations are believed apparent
within the biomechanical models, the associated control circuits and the three ski
binding embodiments. Accordingly, the scope of the present invention is defined only
by the following appended claims.
1. In a method for generating a release signal in a ski binding according to predetermined
parameters for minimizing lower extremity ski injuries, the steps comprising:
formulating a biomechanical model including equations for predicting proximity of
injury to prevent one or more types of lower extremity ski injuries;
providing means in the ski binding for measuring stresses formed by interaction between
a skier and a ski through the binding and for producing electrical signals corresponding
thereto;
programming said biomechanical model equations into a computer means;
communicating said stress signals to said computer means; and,
operating said computer means to predict proximity of injury and thereupon generating
a release signal to initiate release in the binding.
2. The method of claim 1 further comprising the step of formulating the biomechanical
model and equations for assessing proximity of injury relative to any of a combination
of lower extremity components comprising the tibia, ankle and knee.
3. The method of claim 2 wherein the biomechanical model and included equations are
formulated to assess proximity of injury under combinations of different conditions.
4. The method of claim 1 wherein the biomechanical model and included equations are
formulated to assess proximity of injury under combinations of different conditions.
5. The method of claim 1 further comprising the step of formulating the biomechanical
model and included equations relative to torsional and/or bending modes of stress
in assessing proximity of injury.
6. The method of claim 5 wherein said biomechanical model and included equations are
formulated to include inertia, damping, and yieldable stiffness factors.
7. The method of claim 1 wherein said biomechanical model and included equations are
formulated to include inertia, damping and yieldable stiffness factors.
8. The method of claim 1 further comprising the step of including said programmed
computer means as a portion of the ski binding.
9. The method of claim 8 wherein said computer means are adapted for external programming
in order to selectively vary conditions of injury proximity according to any of a
combination of factors including skier physiology, skier ability and skiing conditions.
10. The method of claim 9 wherein said computer means includes digital means adapted
for solving biomechanical model equations by numerical integration techniques.
11. The method of claim 1 wherein said computer means are adapted for external programming
in order to selectively vary conditions of injury proximity according to any of a
combination of factors including skier physiology, skier ability and skiing conditions.
12. The method of claim 11 wherein said computer means includes digital means adapted
for solving biomechanical model equations by numerical integration techniques.
13. The method of claim 1 wherein the biomechanical model is formulated based on a
selected combination of the terms of inertia, damping and stiffness in any combination
of flexible joints of the lower skier extremity.
14. The method of claim 13 wherein the biomechanical model is formulated with the
assumption that the ankle and knee joints of the lower skier extremity are rigid.
15. The method of claim 14 wherein the biomechanical model is formulated using the
term of stiffness alone, loading in the tibia of the lower skier extremity being determined
by displacement transmitted through a hip joint of the lower extremity.
16. The method of claim 14 wherein the biomechanical model is formulated using the
terms of inertia, damping and stiffness with loading in the tibia of the lower skier
extremity being determined by displacement, velocity and acceleration transmission
through a hip joint of the lower skier extremity.
17. A release actuating mechanism for a ski binding including means for releasably
securing a ski boot of a skier to a ski, comprising:
means responsive to an electrical signal for initiating release of the binding;
strain gage means arranged in the binding for producing electrical signals corresponding
to preselected stresses formed by interaction between the skier and ski through the
binding; and,
computer means being in communication with said strain gage means for receiving said
electrical signals, said computer means including means programmed with equations
formulated in a biomechanical model to predict conditions of injury proximity and
thereupon generating a release signal to the release initiating means.
18. The release actuating mechanism of claim 17 further comprising the step of formulating
the biomechanical model and equations for assessing proximity of injury relative to
any of a combination of lower extremity components comprising the tibia, ankle and
knee.
19. The release actuating mechanism of claim 18 wherein the biomechanical model and
included equations are formulated to assess proximity of injury under combinations
of different . conditions.
20. The release actuating mechanism of claim 19 further comprising the step of formulating
the biomechanical model and included equations relative to torsional and/or bending
modes of stress in assessing proximity of injury.
21. The release actuating mechanism of claim 19 wherein said biomechanical model and
included equations are formulated to recognize inertia, damping, and yieldable stiffness
factors.
22. The release actuating mechanism of claim 17 wherein said computer means are adapted
for external programming in order to selectively vary conditions of injury proximity
according to any of a combination of factors including skier physiology, skier ability
and skiing conditions.
23. The release actuating mechanism of claim 22 wherein said computer means includes
digital means adapted for solving the biomechanical model equations by numerical integration
techniques.
24. The release actuating mechanism of claim 17 wherein the ski binding includes releasable
binding means for rigidly engaging the ski boot, said means for initiating release
of the binding being operatively coupled with said releasable binding means.
25. The release actuating mechanism of claim 24 wherein said releasable binding means
is centered about a point located generally along a lower extremity axis of the skier.
26. The release actuating mechanism of claim 17 wherein said strain gage means are
embodied in a dynamometer for accomplishing direct load measurement.
27. A ski binding for releasably securing a ski boot of a skier to a ski, comprising:
releasable binding means for rigidly engaging the ski boot,
a structural strain gage element .interconnected between the rigid binding means and
the ski;
strain gage means arranged on said structural strain gage element for detecting predetermined
modes of stress produced by interaction between the ski boot and ski; and,
computer means in communication with said strain gage means and said releasable binding
means, said computer means including means for determining when the detected stresses
produced by interaction between the ski boot and ski indicate injury proximity and
thereupon generating a signal to initiate release of the ski boot by said binding
means in order to minimize or prevent lower extremity ski injuries.
28. The ski binding of claim 27 wherein the releasable binding means is centered about
a point located generally along extremity axis of the skier.
29. The ski binding of claim 128 wherein said strain gage means are arranged on said
structural strain gage element for detecting both torsional and bending stresses.
30. The ski binding of claim 29 wherein said strain gage means are also arranged upon
said structure in compensating relation to each other.
31. The ski binding of claim 27 wherein the strain gage means are arranged on said
structural strain gage element for detecting both torsional and bending stresses.
32. The ski binding of claim 27 wherein said computer means include means programmed
with equations formulated in a biomechanical model to predict conditions of injury
proximity.
33. The ski binding of claim 27 further comprising the step of formulating the biomechanical
model and equations for assessing proximity of injury relative to any of a combination
of lower extremity components comprising the tibia, ankle and knee.
34. A ski binding for releasably securing a ski boot of a skier to a ski comprising:
an integrally combined dynamometer/releasable binding element adapted for mounting
on the ski, said integrally combined element including releasable binding means for
rigidly engaging the ski boot and dynamometer means for producing a signal representaive
of a predetermined type of stress developed by interaction between said releasable
binding means and the ski;
release actuating means for initiating release of the ski boot by said releasable
binding element, and
computer means in communication with said dynamometer and said release actuating means
for causing release initiation by said release actuating means upon approaching injury
proximity in order to minimize or prevent lower extremity ski injuries.
35. The ski binding of claim 34 wherein the release binding means is centered about
a point located generally along a lower extremity axis of the skier.
36. The ski binding of claim 34 wherein a plurality of strain gage means are arranged
in compensating relation to each other upon said dynamometer means.
37. The ski binding of claim 36 wherein said dynamometer means is formed as a structural
element secured to the ski and including multiple strain rings for mounting said strain
gages.
38. The ski binding of claim 37 wherein each strain ring is formed with a vertical
surface and a relatively inclined surface both disposed perpendicularly to a longitudinal
axis of the ski for supporting said strain gages in compensating relation with each
other.
39. The ski binding of claim 35 wherein said computer means includes means programmed
with equations formulated in a biomechanical model to predict injury proximity.
40. The ski binding of claim 39 further comprising the step of formulating the biomechanical
model and equations for assessing injury proximity relative to any of a combination
of lower extremity components comprising the tibia, ankle and knee.
41. A ski binding for releasably securing a ski boot having a boot plate to a ski,
said ski binding comprising:
a housing defining a generally elongated platform having an upper side, a lower side,
a forward portion, a middle portion and a rearward portion, said middle portion having
a pair of lateral edges;
a pair of clamps, each of said clamps including an upper end portion and a lower end
portion, said housing further including first mounting means for rotationally mounting
each of said clamps in a facing relationship to a different one of each of said lateral
edges, each of said clamps being rotatable between a first position and a second position;
bias means for maintaining each of said clamps in said first position, said upper
end portion of each of said clamps being adapted for securing said boot plate to said
upper side when each of said clamps are in said first position;
dynamometer means for securing each of all forward portions and said rearwad portions
in a spaced apart relationship to said ski and further for measuring dynamic forces
induced beteeen said platform and said ski and operative to develop a plurality of
electrical signals, each of said signals being assocated with a measurement of a different
one of components of said forces; and
control means responsive to said signals for analyzing said signals and operative
to develop a release signal upon one of said components exceeding a predetermined
limit, said bias means being further responsive to said release signal and operative
to rotate each of said clamps to said second positions.
42. A ski binding according to claim 41 wherein said bias means includes:
a generally elongated rod having a first end portion and a second end portion, said
housing further including second mounting means for longitudinally mounting in a spaced
apart * relation each of said end portion and said second end portion underneath said
middle portion;
a generally cylindrical member having an axial bore dimensioned to receive said rod,
said member being mounted in axially slidable engagement on said rod; and
a pair of roller structures, each of said roller structures having an outer end adapted
for mounting to said lower end portion of a different one of each of said clamps in
rotationally slidable engagement, a generally U-shaped inner end defining a pair of
free ends, an elongated member connecting said outer end and said inner end, an axle
mounted to said free ends, a roller rotatably mounted on said axle, and a bias element
arranged for normally biasing each of said roller structures to loosely maintain each
of said clamps in said first position, said axle being arranged generally perpendicular
to said platform, said housing further including third mounting means for supporting
said elongated member of each of said roller structures in linear . slidable engagement.
43. A ski binding according to claim 42 wherein said cylindrical member is positionable
between said roller of each of said roller structures defining a locked position for
biasing each of said roller structures to maintain each of said clamps in said first
position.
44. A ski binding according to claim 43 wherein said bias means further includes:
a solenoid having a plunger, said cylindrical member in said locked position being
axially positioned proximate said plunger.
45. A ski binding according to claim 44 in which said solenoid in response to said
release signal projects said plunger towards said cylindrical member, said plunger
sliding said cylindrical member towards one of said end portions of said rod defining
an unlocked position.
46. The ski binding according to claim 41 wherein said dynamometer means includes:
first strain gage means associated with said forward portion; and
second strain gage means associated with said rearward portion, said first and said
second strain gage means developing said electrical signal in response to said forces.
47. A ski binding according to claim 41 further comprising:
manually operable locking means for selectively engaging said bias means and operative
to selectively position each of said clamps in one of said first position and said
second position.