EP0042762A2

EP0042762A2 - Apparatus for programmed release in ski bindings

Info

Publication number: EP0042762A2
Application number: EP81302824A
Authority: EP
Inventors: Maury L. Hull; Lee Dorius
Original assignee: University of California
Current assignee: University of California
Priority date: 1980-06-24
Filing date: 1981-06-23
Publication date: 1981-12-30
Also published as: EP0042762A3

Abstract

A method and apparatus for achieving programmed. release ski bindings is described including formulation of biomechanical models and associated equations for determining release cirteria in order to minimize selected types of lower extremity ski injuries. Analog and digital (122') control circuits are also disclosed for computing the release variables from the biomechanical model equations and comparing the variable values to the release criteria in order to precisely generate a release initiating signal. Loads measured in the ski binding drive the biomechanical model equations. Three embodiments of ski binding assemblies are also disclosed including releasable binding means (310) for rigidly securing the ski boot (316) to the ski (314) with a release actuating element (318, 342, 334) for releasing the ski from the binding upon occurrence of a release condition as determined by the associated control circuit (122').

Description

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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.

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

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.
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.
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.
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.
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.
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.
Nomenclature for First Biomechanical Model
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.

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.
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.

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.
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.
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 ^K _AB is the release criterion similarly indicating injury proximity as in the medial-lateral analysis of the model.
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

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.
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.
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.
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

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.
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.
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.
Nomenclature for Second Biomechanical Model
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.
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_Hare 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.
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 θ₁ and θ₂ 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 θ₃ is the absolute torso rotation. Because the ski is fixed and the dynamometer is stiff, the leg rotation θ₂ will be quite small so that 9₂, θ₂ and 9₂ all approach zero. Equations (2-3) and (2-4) reduce to
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
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.
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.
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 G₂ which is then subtracted from the measured moment M_z(t). On the other hand, Equation (2-9) requires computation of leg angular acceleration θ₂, angular velocity of the leg θ₂, and leg medial-lateral rotation, e₂. Accordingly, it is believed that Equation (2-8) offers the simplest approach for programming of the computer component in the control circuit.
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

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.
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.
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.
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.
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 e₂ 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.
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

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.
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.
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.
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.
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.
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

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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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

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.
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.
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.
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.
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.
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.
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.
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.
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

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.
Ski binding 410 includes a housing 418, a pair of clamps 420, bias means 422, dynamometer means 424, and control means 426.
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.
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.
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.
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.
The details of control means 426 have been fully described in Figures 1 through 6 herein.
Bias means 422 includes a generally elongated rod 454, a generally cylindrical member 456, and a pair of roller structures 458.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.

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.