U.S. patent application number 14/604372 was filed with the patent office on 2015-07-30 for systems and methods for determining selected exercise resistance.
This patent application is currently assigned to STRENGTH COMPANION, LLC. The applicant listed for this patent is Strength Companion, LLC. Invention is credited to DAVID G. OTEMAN.
Application Number | 20150209609 14/604372 |
Document ID | / |
Family ID | 53678086 |
Filed Date | 2015-07-30 |
United States Patent
Application |
20150209609 |
Kind Code |
A1 |
OTEMAN; DAVID G. |
July 30, 2015 |
SYSTEMS AND METHODS FOR DETERMINING SELECTED EXERCISE
RESISTANCE
Abstract
A system and method for determining a selected weight in
exercise equipment (which may include an incremental weight sensor
disposed on a shaft rotatably fastened with an incremental weight
selection dial). The weight stack incremental sensor produces an
electrical signal related to the dial position. A spring element or
plurality of spring elements are disposed between a reference
member and an unused portion of a weight stack results in spring
displacement during an exercise motion. A weight stack sensor
disposed between the reference member and the unused portion of a
weight stack produces an electrical signal related to displacement.
The sensor electrical signals can be used by an electronics unit to
compute the total weight lifted by a user of exercise
equipment.
Inventors: |
OTEMAN; DAVID G.;
(DELAFIELD, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Strength Companion, LLC |
Delafield |
WI |
US |
|
|
Assignee: |
STRENGTH COMPANION, LLC
Delafield
WI
|
Family ID: |
53678086 |
Appl. No.: |
14/604372 |
Filed: |
January 23, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61931679 |
Jan 26, 2014 |
|
|
|
Current U.S.
Class: |
482/8 ;
482/98 |
Current CPC
Class: |
A63B 2071/065 20130101;
A63B 2220/51 20130101; A63B 71/0686 20130101; A63B 21/0628
20151001; A63B 2220/62 20130101; A63B 2225/20 20130101; A63B
2209/00 20130101; A63B 2225/50 20130101; A63B 2220/20 20130101;
A63B 2220/805 20130101; A63B 2024/0093 20130101; A63B 2220/802
20130101; A63B 21/023 20130101; A63B 24/0087 20130101 |
International
Class: |
A63B 21/062 20060101
A63B021/062; A63B 24/00 20060101 A63B024/00 |
Claims
1. An apparatus comprising: a plurality of weight plates including
a bottom weight plate, the weight plates being at least partially
selectively vertically translatable along a translation path from
an at-rest position; and a sensor configured to measure a
displacement of the bottom weight plate from the at-rest
position.
2. An apparatus according to claim 1, wherein the sensor comprises
a stationary component and a moveable component, wherein the
displacement of the bottom weight plate is automatically measured
by sensing two positions of the moveable component with respect to
the stationary component.
3. An apparatus according to claim 2, the sensor further comprising
a biasing member to bias the moveable component in a first
direction into contact with the bottom weight plate.
4. An apparatus according to claim 3, wherein the biasing member is
a biasing spring having a predetermined bias spring constant.
5. An apparatus according to claim 4, wherein when the weight
plates are positioned at the at-rest position, the bottom weight
plate is at least partially supported by a plurality of weight
stack springs, each weight stack spring having a spring constant
that is at least substantially greater than the spring constant of
the biasing spring.
6. An apparatus according to claim 5, wherein the moveable
component makes physical contact with the stationary component.
7. An apparatus according to claim 6, wherein the sensor comprises
a slide potentiometer.
8. An apparatus according to claim 7, wherein the slide
potentiometer comprises a wiper lever biased by a wiper bias force
in a second direction opposite the first direction, the wiper bias
force being substantially less than the predetermined bias spring
constant.
9. An apparatus according to claim 5, wherein the moveable
component is spaced from the stationary component.
10. An apparatus according to claim 9, wherein the sensor comprises
a linear magnetic encoder.
11. An apparatus according to claim 9, wherein the sensor comprises
a linear optical encoder.
12. An apparatus according to claim 9, wherein the sensor comprises
a capacitive encoder.
13. An apparatus according to claim 2, further comprising an
electronics unit electrically coupled to the sensor, the sensor
providing a sense signal to the electronics unit for signal
processing.
14. An apparatus according to claim 13, wherein the sense signal
comprises an analog signal.
15. An apparatus according to claim 13, wherein the sense signal
comprises a digital signal.
16. An apparatus comprising: a plurality of weight plates including
a bottom weight plate, the weight plates being at least partially
selectively vertically translatable along a translation path from
an at-rest position; a plurality of selectable incremental weights,
each weighing less than each weight plate; and a first sensor
configured to sense a selection of the incremental weights.
17. An apparatus according to claim 16, wherein the selection was
made using a dial fixed to a shaft.
18. An apparatus according to claim 17, wherein the first sensor is
configured to sense a rotational position of the shaft.
19. An apparatus according to claim 18, further comprising: a
second sensor configured to measure a displacement of the bottom
weight plate from the at-rest position.
20. An apparatus according to claim 19, further comprising an
electronics unit electrically coupled to the first sensor and the
second sensor.
21. An apparatus according to claim 20, wherein the electronics
unit is configured to: receive a first sense signal from the first
sensor; determine a first amount of selected incremental weight
based on the first sense signal; receive a second sense signal from
the second sensor; and determine an amount of force removed from
the bottom plate based on the second sense signal.
22. An apparatus according to claim 21, wherein the electronics
unit is further configured to calculate a total lifted weight as
the sum of the first amount of selected incremental weight and the
amount of force.
23. An apparatus according to claim 22, wherein the electronics
unit is further configured to display at least one of the first
amount of selected incremental weight, the amount of force, and the
total lifted weight.
24. An apparatus according to claim 21, wherein the electronics
unit is further configured to: start a timer at a start time upon
detection of a first change in the second sense signal; stop the
timer at a stop time upon detection of a second change in the
second sense signal; and calculate an exercise duration by
subtracting the start time from the stop time.
25. An apparatus according to claim 16, wherein the translation
path is at least partially defined by one or more longitudinal
guide rods extending through the plurality of weight plates, the
apparatus further comprising an electronics unit electrically
connected to the first sensor through an electrically conductive
path comprising at least a portion of the guide rods.
26. A method comprising the step of: conducting electricity along a
conductor, the conductor comprising a portion of a first guide rod,
wherein the guide rod comprises a longitudinal rod on an exercise
machine, the rod extending through a plurality of weight plates,
the weight plates being at least partially selectively translatable
along a translation path from an at-rest position.
27. A method according to claim 26, further comprising the step of
sensing a first voltage across a first resistor in electrical
communication with the conductor, the second voltage being caused
by the conducting step.
28. A method according to claim 27, further comprising the step of
sensing a second voltage across a second resistor in electrical
communication with the conductor at a different time than the first
resistor, the second voltage being caused by the conducting
step.
29. A method according to claim 28, wherein the exercise machine
further comprises a plurality of selectable incremental weights,
each weighing less than each weight plate, and further wherein the
first voltage corresponds to a first selection of the incremental
weights and the second voltage corresponds to a second selection of
the incremental weights.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of co-pending U.S.
Provisional Patent Application Ser. No. 61/931,679, filed 26 Jan.
2014, and entitled "System and method for determining weight
selected in exercise equipment," which is incorporated herein by
reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] This invention relates generally to the field of exercise
equipment, and more specifically, systems and methods to enable
monitoring selectively variable attributes of such equipment during
an exercise motion.
[0003] Methods to detect weight lifted by a user of an exercise
machine have been disclosed in prior patents and demonstrated in
commercially available exercise equipment. Electronic detection of
an amount of weight lifted or selected on or in connection with an
exercise machine is known to be beneficial to a user of the
exercise equipment; for example, the detected weight can be used in
an electronic display of real-time fitness feedback to a user (e.g.
number of repetitions, number of calories burned per repetition or
over a predetermined time, etc.), or for electronically storing a
workout history of a user, so that the user is able to conveniently
track progress of a specific fitness or therapeutic goal. Specific
workout tracking features that combine other sensor information,
along with the detected value of selected weight have been
demonstrated in commercial products and cited in prior patents.
These features include and are not limited to computing work
exerted on the weight stack and power exerted on the weight stack
by the user of the exercise equipment.
[0004] For example, load cells have been used to detect an amount
of weight lifted. The load cell is mechanically connected on one
end to the weight stack and on the other end to the mechanical
cable or belt. The load cell detects both the static value of the
selected weight as well as the forces that arise due to motion of
the weight stack. Because the load cell is rigidly attached to the
mechanical cable of the exercise equipment the electrical wire
connection of the load cell must be designed to tolerate the motion
of the weight stack, without being damaged, for example, by
fatigue. This represents a significant drawback because it is
costly to make an electrical wire connection that can reliably
tolerate such motions. In addition, accurate load cells are
generally expensive transducers, especially load cell types that
rely on a strain gage element.
[0005] As another example, proximity sensors have been used to
detect motion of a weight stack and, with a priori knowledge of the
dimensions of the weight stack plates, the weight could be
estimated. These techniques exhibit significant delay to compute
the weight lifted because often substantial motion must occur
before the profile of the selected weight stack is known. These
techniques also must be calibrated for every different weight stack
attribute, such as a varied dimension of the weight plate. For
these reasons, this prior method has significant practical
drawbacks.
[0006] Non-contact methods of weight detection have also been
disclosed. In one embodiment of such arrangement, an
electromagnetic wave emitter and receiver are located on a
stationary member of the machine and an electromagnetic wave
reflecting device is located on the weight selector pin. An
electronics unit generates the transmitted signals and processes
the received signals to determine the distance of the weight
selector pin. Since the weight plates have a known dimension the
electronics unit is able to compute the weight selected based upon
the distance measurement. An alternative embodiment may use an
infrared sensor instead of the electromagnetic sensor. This prior
technique may have certain drawbacks, such as use of a unique
selector pin. Accordingly, if the weight stack selector pin is
lost, which is common, and a generic replacement pin is used the
system cannot function properly. Also, the weight stack selector
pin provides only a small reflective surface which is difficult to
accurately target with a transmitter, resulting in inaccurate
measurements of position, especially for pin locations that
correspond to a longer distance between the pin and the
transmitter.
[0007] Another non-contact method uses an optical, or light-based
sensor for detecting motion of the weight stack. A light reflector
is used on the quasi-stationary (i.e., unused during exercise)
portion of the weight stack, which may decrease sensitivity to
weight plate dimensions. However, the use of optical sensors can
result in sensitivity to dust and dirt build-up, which can cause
degraded performance, such as a loss of accuracy, within the
lifetime of the exercise equipment. Further, a light emitter and
light detector arrangement may have a non-linear characteristic in
function of position. This non-linear characteristic depends on
many factors such as the light transmitter manufacturing tolerance,
the degradation of the photo transmitter with time, and the exact
mounting arrangement of the components, thus the technique requires
extensive and precise calibration procedure for each sensor
installation. Prior optical systems may also require significant
electrical power. Increased power consumption is undesirable, for
example, if the system is required to function from a source of
battery power, solar power, or a source of power other than power
mains. Still another drawback of the technique is that very short
distance sensing is not well-suited to optical techniques.
Time-of-flight measurement techniques are the most robust and
common optical distance measurement techniques used, for example in
laser distance meters, and are not practical in this arrangement
due to the time of flight of the light being too short to measure
with sufficient precision.
[0008] Accordingly, the art of determining and recording and/or
displaying a selective resistance to an exercise motion may benefit
from systems and methods that address one or more drawbacks
experienced by prior systems and/or methods, or that advance
information gathering, tracking, computation and/or display as it
relates to exercise machines.
SUMMARY OF THE INVENTION
[0009] According to an aspect of an embodiment of an apparatus
according to the present invention, such apparatus may include a
plurality of weight plates including a bottom weight plate. The
weight plates may be at least partially selectively vertically
translatable along a translation path from an at-rest position. The
apparatus may also include a sensor configured to measure a
displacement of the bottom weight plate from the at-rest position.
The sensor may include a stationary component and a moveable
component, wherein the displacement of the bottom weight plate is
automatically measured by sensing two positions of the moveable
component with respect to the stationary component. The moveable
component may be in physical contact with the stationary component
(e.g., if the sensor includes a slide potentiometer) or may be
spaced therefrom (e.g., if the sensor includes a magnetic, optical
or capacitive encoder). A biasing member (e.g., a spring having a
predetermined bias spring constant) may be included as a part of
the sensor to bias the moveable component in a first direction into
contact with the bottom weight plate. When the weight plates are
positioned at the at-rest position, the bottom weight plate may be
at least partially supported by a plurality of weight stack
springs, each weight stack spring having a spring constant that is
at least substantially greater than the spring constant of the
biasing spring. If the sensor includes a slide potentiometer, it
may include a wiper lever biased by a wiper bias force in a second
direction opposite the bias direction of the moveable component,
the wiper bias force being substantially less than the
predetermined bias spring constant. An electronics unit may be
electrically coupled to the sensor, the sensor providing a sense
signal to the electronics unit for signal processing. The sense
signal may be an analog signal or a digital signal.
[0010] According to an additional or alternative aspect of an
embodiment of an apparatus according to the present invention, such
apparatus may include a plurality of weight plates including a
bottom weight plate. The weight plates may be at least partially
selectively vertically translatable along a translation path from
an at-rest position. The apparatus may further include a plurality
of selectable incremental weights, each weighing less than each
weight plate. A first sensor may be configured to sense a selection
of the incremental weights. The selection of incremental weights
may be made using a dial fixed to a shaft. The sensor may be
configured to sense a rotational position of the shaft. A second
sensor may be configured to measure a displacement of the bottom
weight plate from the at-rest position. An electronics unit may be
electrically coupled to the first sensor and the second sensor.
[0011] The electronics unit may be configured to receive a first
sense signal from the first sensor and determine a first amount of
selected incremental weight based on the first sense signal. The
electronics unit may additionally or alternatively receive a second
sense signal from the second sensor and determine an amount of
force removed from the bottom plate based on the second sense
signal. The electronics unit may be either or further configured to
calculate a total lifted weight as the sum of the first amount of
selected incremental weight and the amount of force. The
electronics unit may be either or further configured to display at
least one of the first amount of selected incremental weight, the
amount of force, and the total lifted weight. The electronics unit
may be either or further configured to start a timer at a start
time upon detection of a first change in the second sense signal
and stop the timer at a stop time upon detection of a second change
in the second sense signal. A calculation may then be made of an
exercise duration by subtracting the start time from the stop time.
the translation path is at least partially defined by one or more
longitudinal guide rods extending through the plurality of weight
plates, the apparatus further comprising an electronics unit
electrically connected to the first sensor through an electrically
conductive path comprising at least a portion of the guide
rods.
[0012] According to an aspect of an embodiment of a method
according to the present invention, the method includes the step of
conducting electricity along a conductor, the conductor comprising
a portion of a first guide rod, wherein the guide rod comprises a
longitudinal rod on an exercise machine, the rod extending through
a plurality of weight plates, the weight plates being at least
partially selectively translatable along a translation path from an
at-rest position. The method may further include the step of
sensing a first voltage across a first resistor in electrical
communication with the conductor, the second voltage being caused
by the conducting step. The method may further include the step of
sensing a second voltage across a second resistor in electrical
communication with the conductor at a different time than the first
resistor, the second voltage being caused by the conducting step.
The exercise machine may further include a plurality of selectable
incremental weights, each weighing less than each weight plate, the
first voltage corresponding to a first selection of the incremental
weights and the second voltage corresponding to a second selection
of the incremental weights.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a first elevation view of an exemplary exercise
machine incorporating embodiments according to the present
invention.
[0014] FIG. 2 is a second, partial elevation view of the machine of
FIG. 1, opposite the view of FIG. 1.
[0015] FIG. 3A is a partial assembly elevation view of a first
embodiment of a weight stack position sensor according to the
present invention.
[0016] FIG. 3B is a partial assembly elevation view of a second
embodiment of a weight stack position sensor according to the
present invention.
[0017] FIG. 4 is a schematic view of a first embodiment of a weight
stack position sensor according to the present invention.
[0018] FIG. 5A is a graphical representation of an exemplary
relationship of a weight stack sensor electrical signal and
associated mechanical displacement.
[0019] FIG. 5B is a graphical representation, in the time domain,
of the weight stack sensor electrical signal during an exercise
motion.
[0020] FIG. 6 is a partial cross-section view taken along line 6-6
in FIG. 2.
[0021] FIG. 7A is a first partial cross-section view taken along
line 7-7 of FIG. 6.
[0022] FIG. 7B is a second partial cross-section view taken along
line 7-7 of FIG. 6.
[0023] FIG. 8A is an electrical schematic for a first embodiment of
an incremental weight sensor according to the present
invention.
[0024] FIG. 8B is an electrical schematic for a second embodiment
of an incremental weight sensor according to the present
invention.
[0025] FIG. 8C is an electrical schematic for a third embodiment of
an incremental weight sensor according to the present
invention.
[0026] FIG. 8D is a graphical representation of the incremental
weight stack sensor electrical signal relative to a rotary position
of an incremental selector dial.
[0027] FIG. 9 is a block diagram electrical schematic
representation of a signal processing arrangement of a weight stack
sensor and incremental weight sensor according to the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0028] Although the disclosure hereof is detailed and exact to
enable those skilled in the art to practice the invention, the
physical embodiments herein disclosed merely exemplify the
invention which may be embodied in other specific structures. While
the preferred embodiment has been described, the details may be
changed without departing from the invention, which is defined by
the claims.
[0029] Turning now to the Figures, FIGS. 1 and 2 present an
embodiment 100 of an exercise machine, or piece of exercise
equipment, which may include embodiments of systems according to
the present invention. The exercise equipment 100 preferably
includes a selective resistance, such as a weight stack 110 having
a plurality of weight plates 112, including a top weight plate 112t
and a bottom weight plate 112b. Unselected or at-rest weight plates
112 rest on a plurality of springs 114 disposed vertically beneath
the weight stack 110, such as between the bottom weight plate 112b
and a lower frame member 116 of the exercise equipment 100. The
selected load plates 112 of the weight stack 110 translate along a
path defined at least partially by one or more guide rods 118,
which in one embodiment may include a first guide rod 118a and a
second guide rod 118b. The guide rods 118 typically have a
substantially circular cross sectional shape. The weight stack 110
may interface to the guide rods 118 through a plurality of bearings
120 which may be fastened on the top weight plate 112t and at least
partially circumferentially disposed around guide rods 118. The
guide rods 118 typically extend vertically between the lower frame
member 116, located below the weight stack 110, and an upper frame
member 117 located above the weight stack 110. Generally, each
guide rod 118 is preferably constructed from a conductive guide rod
member 119, e.g., a first guide rod conducting member shown in FIG.
2A, having a low electrical resistivity material property, which
may include a common steel or steel alloy. Each guide rod 118 may
further include or support an insulating guide rod member 121,
having a high electrical resistivity material property, for
example, a high strength plastic. The insulating member 121 may be
adapted to prevent electrically conductive contact between the rod
118 and any of the weight stack plates 112. Each end of each guide
rod 118 may be mechanically secured to each of the lower frame
member 116 and the upper frame member 117 by a guide rod seat 123
The guide rod seat 123 is preferably constructed of a material
having a substantially insulative electrical property, for example
a plastic polymer, PVC, or rubber.
[0030] The exercise machine 100 may further include an incremental
weight stack assembly 150, which may be fastened to the top weight
plate 112t of the weight stack 110. The incremental weight stack
assembly 150, as is generally known in the art, preferably
comprises a plurality of incremental weights 152, the incremental
weights 152 having a weight measurement that is typically less than
the weight of a single weight plate 112. For example a weight plate
112 may have a nominal weight of about twenty pounds, whereas each
incremental weight 152 may have a lower nominal weight, such as a
factor of the nominal weight of the weight plate 112 (e.g., one
pound, two pounds, two-and-a-half pounds, four pounds, five pounds,
or ten pounds). The incremental weights 152 are guided by an
incremental weight guide track 154 and are typically not supported
by the weight stack springs 114. The incremental weight stack
assembly 150 further comprises a weight selector dial 156 rotatably
supported by a shaft 158, the shaft 158 rotatably fastened to a
selector mechanism 160 (see FIG. 6). The selector mechanism 160 is
mechanically coupled to a plurality of selector rods 162, which
engage the proper incremental weight plates 152, according to the
position of the incremental weight selection dial 156. Incremental
weight selection apparatus are utilized by several manufacturers
and are pervasive in modern exercise equipment. A variety of
incremental weight stack apparatus 150 are employed in the industry
to accomplish the similar function. The incremental weight
selection assembly 150 provided in FIGS. 2A, 2B, 2C, and 2D of the
present disclosure are intended for exemplary purposes only and
should not be viewed as a limitation of the present invention. The
incremental weight selection assembly 150 is intentionally depicted
in a simplified form to better illustrate the function and
advantages of embodiments of systems and methods according to the
present invention.
[0031] According an embodiment of the present invention, a weight
stack sensor 200 may be coupled to or form a portion of the
exercise machine 100. Referring more particularly to FIG. 3A, the
weight stack sensor 200 may be in electrical communication with an
electronics unit 300, such as by a weight stack sensor electrical
cord 302, comprising a plurality of signal and supply wires.
Generally, the weight stack sensor 200 is disposed between the
bottom plate 112b of the weight stack 110 and a reference member,
such as the lower frame member 116. The weight stack position
sensor 200 has two members that move with respect to one another,
which may include a stationary member 210 and a moving member
250.
[0032] The stationary member 210 preferably includes a housing 211
affixed to the reference member, such as the lower frame member
116. The housing 211 may be substantially closed to assist in
maintaining a clean sensor arrangement, or it may be provided in an
open frame or truss structure. The housing 211 generally provides
structural support for the sensor 200.
[0033] The moving member 250, such as a plunger 252, preferably
extends through the housing 211 and is biased longitudinally
outward therefrom by a biasing member 254, such as a coil spring
256. The biasing member 254 may be compressed between the plunger
252 and the housing 211, or the biasing member 254 may extend
through the housing 211 and be compressed between the plunger 252
and the reference member (e.g., bottom frame member 116). The
plunger 252 has a distal end 252a, which is adapted to contact a
portion of the weight stack 110, such as the bottom plate 112b.
Alternatively, the plunger 252 distal end 252a may be affixed to
the weight stack 110. The weight stack position sensor stationary
member 210 includes a guide bearing 212 to direct a sliding
movement of the moving member 250.
[0034] In one embodiment of the present invention, the weight stack
spring 114 has a known characteristic, k.sub.s, that relates the
spring displacement, x, and the spring force, F.sub.s, according to
the following equation:
F.sub.s=k.sub.sx (EQ 1)
While the bias spring 256 could be the same as the weight stack
springs 114, it is preferred to utilize a bias spring 256 that has
a spring constant that is significantly less than the spring
constant k.sub.s of the weight stack springs 114, such that the
function of the spring 256 is primarily to maintain the plunger 252
biased vertically upward and to overcome any opposing bias of a
sensing element 220, as described below. Herein, the spring
characteristic of a weight stack spring 114 is referred to as the
spring constant, k.sub.s, and is assumed to be constant for
convenience in clearly describing the present invention. Those who
are skilled in the art will recognize that the spring constant
k.sub.s may also be a non-linear coefficient, having a
characteristic that changes as a function of spring displacement,
without departing from the scope and intent of the present
invention. Those who are skilled in the art will also recognize
that any variety of spring types and springs constructed of various
materials may be applied without departing from the scope and
intent of the present invention. Spring types that may be used for
the weight stack springs 114 or the plunger bias member 254 include
but are not limited to coil springs, conical coil springs,
elastomer springs, air springs, gas-filled springs, and/or rubber
or polymer springs.
[0035] The position sensor 200 has a means of accurately detecting
a position of the moving member 250 relative to the stationary
member 210. Detection may be accomplished with a sensing element
220 and a means of producing an electrical signal, which is
deterministically related to the position of the moving member 250,
relative to the stationary member 210. In one embodiment (see FIG.
4) of the present invention the weight stack position sensor
sensing element 220 incorporates an electrical potentiometer 222,
comprising a three terminal resistive element, a first terminal 224
connected to a voltage supply 325, a second terminal 226 connected
to a voltage supply return. A third, wiper terminal 228, is
electrically connected to a wiper 230 (moveable by a wiper lever
232, which is preferably biased downwardly against a wiper lever
seat 253 provided on the plunger 252), which creates a voltage
divider, providing a position indication, such as a sense voltage
SV, to the electronics unit 300. The sense voltage SV is typically
less than or equal to the voltage of the voltage supply 325, and is
generally proportional to the displacement of the sensor plunger
252. The weight stack sensor 200 is electrically connected to the
electronics unit 300 via the weight stack sensor electrical cord
302 comprising a plurality of wires. The electronics unit 300 is
capable of computing parameters, including, e.g., an amount of
weight lifted and/or a time of a weight lifting exercise, based
upon the sense voltage SV. While the position indication is
preferably a voltage, it may also be a current, or a digital
communication message if the sensor 200 is equipped with an
appropriate apparatus. The position sensor moving member 250 is
firmly attached to the wiper lever 232, which moves responsive to
and preferably in direct proportion to the movement of the position
sensor moving member 250.
[0036] Those who are skilled in the art will recognize that a
variety of techniques may be used as the position sensing element
220, without departing from the scope and intent of the present
invention. Referring to FIG. 3B, for example, an exemplary
alternative position sensor 400 is shown, where like reference
numerals refer to at least substantially similar or identical
structure having similar function as those elements of the
embodiment of FIG. 3A, except where otherwise indicated. Rather
than contact the plunger 452, however, this embodiment 400 includes
a non-contact sensor element 420, including a magnetic encoder
strip 458 disposed on the plunger 452 and a magnetic sensor read
head 460 disposed substantially orthogonally to, and spaced by a
suitable read gap 462 from, the strip 458. Other sensing element
types include both contact types and non-contact types and include
but are not limited to ultrasonic sensors, magnetic sensors and
encoders, capacitive sensors and encoders, and optical sensors and
encoders.
[0037] Referring now also to FIG. 5A and FIG. 5B, the function of
the weight stack position sensor 200 may be more fully explored.
Prior to a user initiating an exercise motion, a weight stack 110
comprising a plurality of weight plates 112 rests on a plurality of
springs 114. The springs 114 are compressed according to a combined
spring constant of the plurality of springs 114, for example, for
the case of n springs with a spring constant k.sub.s, the combined
spring constant k.sub.c can be computed according to the following
equation:
k.sub.c=n*k.sub.s (EQ 2)
The position sensor 200 produces a first sense voltage SV.sub.0,
representing a first position WS.sub.0 of the sensor moving member
250, relative to the position sensor stationary member 210.
Referring to FIG. 5A, when a user performs an exercise motion
(e.g., at least some of the weight stack 110 is displaced), the
bottom weight plate 112.sub.b displaces by an amount determined by
the combined spring constant, k.sub.c, and the position sensor
produces a second sense voltage S.sub.1, representing a second
position WS.sub.1 of the position sensor moving member 250,
relative to the sensor stationary member 210. Herein, the change in
position of the position sensor moving member 250, relative to the
stationary member 210, due to an exercise motion will be referred
to as the sensor displacement. In one embodiment of the present
invention, referring to FIG. 5A, the sense voltage SV changes in
direct proportion with the sensor displacement, and therefore
changes in direct proportion to the weight lifted by the user.
[0038] The sense voltage SV may be used to determine the amount of
weight lifted off of the stack 110. Referring to FIG. 9, an
electronics unit 300, comprising an analog-to-digital converter, a
microcontroller, and memory is able to store in non-volatile memory
a previously calibrated value of the combined spring constant,
k.sub.c. The memory may also be used to store calculated parameters
and log usage of the exercise machine 100. The electronics unit
300, having monitored a scaled electrical signal x.sub.e
proportional to the sensed voltage SV, is able to use the signal
x.sub.e as received from the sensor 200 or convert the scaled
electrical signal x.sub.e to a digital word for signal processing,
typically by a microcontroller. The electronics unit 300 is able to
compute the weight, F, defined in units of force (for example,
Lbs-Force in English units or Newtons in SI units), according to
Equation 3 (EQ 3). The electronics unit 300 can also compute the
mass of the weight lifted from the stack, M.sub.wsl, according to
Equations 3 (EQ 3) and 4 (EQ 4):
F=k.sub.c*x.sub.e (EQ 3)
M.sub.wsl=M.sub.ws-F/g (EQ 4)
In EQ 4 the constant, g, represents the acceleration due to gravity
and has a typical value of g=9.81 m/s.sup.2 at the surface of the
earth. In EQ 4 the weight stack mass M.sub.ws is the mass supported
by the springs 114. Depending on the design of the incremental
weight selector assembly 150, the weight stack mass M.sub.ws may
also include the mass of the incremental weights 152 and or the
assembly 150. To reiterate, the combined spring constant, k.sub.c,
may also be a non-linear coefficient, having a characteristic that
changes as a function of spring displacement. Those who are skilled
in the art will appreciate that a non-linear characteristic can be
processed by the electronics unit 300, typically within a
microcontroller and can still be effective for determining the
weight and/or mass lifted by the user.
[0039] When a user completes an exercise motion, sometimes referred
to as an exercise set, the entire weight stack 110 is resting on
the springs 114. The springs 114 are compressed, according to the
combined spring constant k.sub.c and the corresponding sensor
displacement (WS.sub.1-WS.sub.0) is calculated by the electronics
unit 300. In FIG. 5B, an exemplary waveform of the sense voltage SV
during an exercise motion is provided. The sense voltage SV has a
first electrical signal value SV.sub.0, associated with the
position of the weight stack 110 when it is in a rest position, and
a second electrical signal value SV.sub.1, associated with an
exercise motion (e.g., at time period during which a portion of the
weight stack 110 has been removed from contact with the remainder
of the weight stack 110, the remainder including the bottom weight
plate 112.sub.b, or during which the entire weight stack 110 has
been removed from contact with the springs 114). The waveform in
FIG. 5B is representative of an exercise in which a portion of the
weight stack 110 is lifted and the weight thereof is not
transferred back to the springs 114 until the exercise is complete.
In an alternative exercise, at least a portion of the amount of
weight of a lifted portion of the weight stack 110 may be
transferred to the springs 114, in which case oscillations may
occur in the sensed voltage SV throughout a set of exercise
repetitions. In one embodiment of the present invention, the weight
stack sensor displacement detected by the electronics unit 300 is
used to determine the occurrence of initial exercise motion, the
occurrence of a completed exercise motion, and the duration of the
exercise motion.
[0040] In another embodiment, alone or in combination with the
weight stack sensor 100, an incremental weight sensor 500 may be
connected to the electronics unit 300 and scaled electrical signals
associated therewith may be created in the electronics unit 300.
The incremental weight sensor 500 is preferably electrically
connected to the electronics unit 300, at least in part, by the
guide rods 118. A first guide rod conducting member 502 is
electrically connected in series with an incremental sensor
electrical cord 504, comprising one or a plurality of signal and
supply wires. The first guide rod conducting member 502 may be
electrically connected with the cord 504 through the bearing, as
later described. A second guide rod conducting member 506 is
electrically connected in series with an incremental sensor supply
cord 508, comprising one or a plurality of signal and supply
wires.
[0041] Referring to FIG. 6, in one embodiment of the present
invention, a position sensing means, preferably a multi-position
electrical switch 510 is rotatably coupled to the incremental
weight selector assembly 150, preferably being mounted to the
rotating shaft 158. In this arrangement, a rotary position of the
switch 510 generally relates directly to the rotary position of the
incremental selector dial 156, as depicted in FIG. 8D. For example,
a first incremental dial rotary position D.sub.1 corresponds to a
first rotary position of the multi-position electrical switch 510,
and a second incremental dial rotary position D.sub.2 corresponds
to a second rotary position of the multi-position electrical switch
510, and so on. Referring again to FIG. 6, a sensor supply wire 550
is electrically connected to a first bearing 552 and the
multi-position electrical switch 510, preferably the pole 512 of
the switch 510. A plurality of throw terminals 514 of the
multi-position electrical switch 510 may be connected electrically
to a plurality of passive impedance elements 516, for example,
resistors, by a plurality of electrical wires 518. The resistors
may be mounted to a resistor PCB assembly 520, in turn, the
resistor PCB assembly 520 is fastened to a translating member of
the exercise equipment 100, for example, the incremental weight
selector assembly 150 or the top weight plate 112t. A incremental
sensor signal wire 554 is electrically connected to an electrically
a second bearing 556 and may further be connected to the plurality
of passive impedance elements 516, for example resistors, that may
be mounted to the resistor PCB assembly 520. The amount of
electrical current flowing in the incremental sensor supply wire
550 is preferably substantially the same as the electrical current
flowing in the incremental sensor signal wire 554.
[0042] Pertaining to the incremental weight sensor 500, other
sensing means may be applied and fall within the scope of the
present invention. For example, an electrical potentiometer
rotatably coupled to the shaft 158 may be used in place of the
multi-position electrical switch 510 and a portion of or all of the
impedance elements. Other incremental weight sensing means are
generally contemplated and include and are not limited to
potentiometers, encoders, and proximity sensors. Other sensor
arrangements disposed on other mechanical members of the
incremental weight stack assembly 150, for example, the incremental
selector rods 162 are also contemplated in the present
disclosure.
[0043] As previously indicated, the switch 510 is preferably
electrically coupled to the electronics unit 300 through the guide
rods 118, preferably through a conductive bearing disposed on each
guide rod 118. Referring now to FIG. 7A, a first embodiment 600 of
a conductive bearing is shown. The bearing 600 preferably includes
a number of elements commonly known to bearings and in particular
linear bearings, including a plurality of ball bearings 602, one or
more ball bearing tracks 604, sometimes referred to as bearing
raceways or channels, a dust cover or wiper 606 or plurality of
wipers 606 (which may be electrically conductive), and a bearing
housing 608. The elements of the bearing are preferably constructed
of an electrically conductive material, such as a metallic
material. The plurality of ball bearings 602 are in mechanical
contact (i.e. rolling frictional contact) with the guide rod
conducting member 502 or 506, and may form an electrically
conductive path, preferably having low electrical impedance,
through which an electrical current may flow. For example, an
impedance of less than 1,000 Ohms (1 k.OMEGA.) between a bearing
housing 608 and a guide rod conducting member 502 or 506. The
electrically conductive path may have a substantially resistive,
capacitive, or inductive impedance characteristic, or some
combination thereof. The bearing 600 is mounted to the top weight
plate 112t via a bearing insulator 610. The bearing insulator 610
forms a substantially high electrical impedance between the bearing
housing 608 and the top weight plate 112t, for example, an
impedance greater than 10 M.OMEGA. of resistance between the
bearing housing 608 and the top weight plate 112t. As indicated
above, the guide rod 118 may have or support an additional guide
rod insulating member 121 that comprises an electrically insulating
material, for example a high strength polymer, that has a large
electrical resistivity property. The interface between the guide
rod insulating member 121 and the guide rod conductive member 502
or 506 can be located anywhere along the length of the guide rod
118; as one example, the interface may be located substantially at
the center of the thickness of top weight plate 112t when the
weight stack 110 is in the at-rest position as depicted in FIG. 2C
and FIG. 2D. In an alternative embodiment of the present invention,
the guide rod 118 may only comprise a guide rod conductive member
502 or 506, without the insulating member 121. As already described
in the present disclosure, the guide rod ends are mechanically
located via guide rod seats 123 that have an electrically
insulating material property.
[0044] Those who are skilled in the art will recognize that a
variety of bearing types may be used without departing from the
scope and intent of the present invention. Bearing types include
and are not limited to linear bearings, sleeve bearings, slide
bearings, and various arrangements of these and other bearings.
FIG. 7B illustrates an alternative embodiment 700 of the present
invention wherein a sleeve bearing 702 is utilized instead of ball
bearings 602. Regardless of the bearings used, an electrically
conductive path is established preferably from a power supply 570,
through the supply cord 504, through the first rod 118a, through a
first bearing frictional member (e.g. ball bearings 602), through a
first bearing housing (e.g. 608), through the supply wire 550
(which may be secured to the housing with a screw), through the
switch 510 and PCB 520 (or other sensor and/or related circuit),
through the signal wire 554, through a second bearing housing (e.g.
608), a second bearing frictional member (e.g. ball bearings 602),
through the second rod 118b, and through the signal cord 508.
[0045] Referring to FIG. 8A, an electrical schematic of a preferred
embodiment of the incremental weight sensor 500 is illustrated,
also depicting the equivalent electrical attributes of the bearings
602. An incremental sensor electrical supply 570 is established,
typically by the electronics unit 300. The supply 570 is typically
a DC (FIG. 8A) or AC (FIG. 8B) voltage source supply, but may
alternatively be an AC or DC current source supply. A complete
electrical circuit network is formed by the incremental sensor
supply 570, the multi-position electrical switch 510, a first
resistor 516a connected to a first switch throw 514a, a second
resistor 516b connected to a second switch throw 514b, and a third
resistor 516c connected to a third switch throw 514c, and a
termination resistor 572. A fourth switch throw 514d may be left as
open circuit. Circuitry within the electronics unit 300 measures
the signal, typically a voltage, across the termination resistor
572. In FIG. 8A the electrical effect of the bearings 602 are
represented by an equivalent bearing contact resistance 530. The
value of the sensor resistors 516 and termination resistor 572 and
other impedances that may be employed are preferably selected to be
much greater than the value of the bearing contact resistance
530.
[0046] Referring again to FIG. 8A, the electrical connection of the
first sensor resistor 516a connected to the switch pole 512 by the
first switch throw 514a corresponds to a first mechanical position
of the multi-position electrical switch 510. As previously
described in the present disclosure, a first mechanical position of
the multi-position electrical switch 510 corresponds to a first
mechanical position of the incremental weight selector dial 156.
Referring now to the graph of FIG. 8D, a resulting deterministic
relationship exists between the rotary position of the incremental
weight selector dial 156 and an incremental sensor scaled
electrical signal created in the electronics unit 300 from the
voltage developed across the termination resistor 572. A first
incremental sensor electrical signal level SL.sub.1 is created for
a first rotary position D.sub.1 of the incremental weight selector
dial 156, a second incremental sensor electrical signal level
SL.sub.2 is created for a second rotary dial position D.sub.2, a
third incremental sensor electrical signal level SL.sub.3 is
created for a third rotary dial position D.sub.3, and finally a
fourth incremental sensor electrical signal level SL.sub.4 is
created for a fourth rotary dial position D.sub.4. The sensor
resistors 516 are preferably selected such that the first
incremental sensor electrical signal level SL.sub.1, a second
incremental sensor electrical signal level SL.sub.2, a third
incremental sensor electrical signal level SL.sub.3, and a fourth
incremental sensor electrical signal level SL.sub.4 have
substantially different values. The electronics unit 300 can
readily measure and compute the incremental weight selected by
employing well-known ADC circuits and digital signal processing
techniques.
[0047] In one embodiment of the present invention, the
multi-position electrical switch 510 comprises a single pole 512,
four throw 514 type switch. As previously stated in the present
disclosure, and reiterated now, the switch type should not be
considered as a limitation of the present invention. Those skilled
in the art will readily recognize that there are a variety of
switch types and switch arrangements that may be applied and remain
within the scope and intent of the present invention. For example,
in an exercise machine 100 comprising only two incremental weights
(and therefore a selection dial with three positions), a single
pole, triple throw switch may be a more appropriate switch
type.
[0048] The incremental weight sensor 500 may comprise a variety of
alternative sensing elements and arrangements without departing
from the scope and intent of the present invention. These include
and are not limited to rotary and linear potentiometers, rotary and
linear proximity sensors, rotary and linear encoders, and
accelerometers employing a variety of sensing technologies.
[0049] In an alternative embodiment 500' of an incremental sensor
according to the present invention, referring to FIG. 8B, the
electrical effect of the bearing 600 or 700 may be better
represented by a bearing capacitance 540, and the incremental
sensor supply 570 is preferably an AC supply having a substantially
high frequency characteristic, for example, a frequency greater
than 10 kHz. Lower frequency supplies may also be used.
[0050] In FIG. 8C, an alternative embodiment 500'' of the present
invention is depicted, wherein the incremental weight sensor
comprises a plurality of proximity sensors 510'' preferably coupled
to the shaft 158.
[0051] Referring to FIG. 9, the electronics unit 300 is capable of
computing parameters as discussed herein, based upon the weight
stack sensor sense voltage SV and/or the incremental electrical
signal level SL. Generally, the electronics unit 300 comprises
circuits for processing sensor signals, and typically includes
analog and digital gain circuits, analog-to-digital conversion
circuits, microprocessors or DSP's, memory, displays including but
not limited to LCD and LED displays, wireless communication
devices, and other digital and analog circuitry. The electronics
unit 300 may be dedicated to the function of determining weight
lifted and, more generally, the electronics unit 300 referred to in
this invention pertains to an electronic feedback system, and can
be used for multiple functions in addition to processing the sensor
electrical signals and computing the incremental weight selected
and/or the amount of weight of the portion of the weight stack 110
lifted by the user.
[0052] Referring now to FIG. 9, the electronics unit 300 preferably
computes each of the incremental weight selected and/or the weight
stack lifted weight, and further computes the mass of the total
weight lifted, M.sub.tot, by computing the sum of the computed mass
of the weight stack lifted, M.sub.wsl, (previously described in the
present disclosure) and the computed mass of the incremental
weight, M.sub.inc, according to Equation 5 (EQ 5).
M.sub.tot=M.sub.wslM.sub.inc (EQ 5)
With the total mass of the weight lifted known, the total weight or
force (e.g., in units of Lbs) can also be computed by the
electronics unit by simply multiplying the total mass by the
gravitational constant, g, discussed above. In an alternative
embodiment of the present disclosure, sensing elements generally
known for motion sensing, for example, accelerometers, and
electronic circuits located on the weight stack members are powered
from the electronics unit 300. Electronic circuits on the weight
stack 110 (such as in the incremental weight selector 150) or in
the electronics unit 300 may generally further comprise wireless
communication devices for transmitting data wirelessly to one or a
plurality of receiving devices or network nodes, such as local area
network (LAN) nodes.
[0053] The foregoing is considered as illustrative only of the
principles of the invention. Furthermore, since numerous
modifications and changes will readily occur to those skilled in
the art, it is not desired to limit the invention to the exact
construction and operation shown and described. While the preferred
embodiment has been described, the details may be changed without
departing from the invention, which is defined by the claims.
* * * * *