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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Turning now to the Figures,
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
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
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.
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.
In one embodiment of the present invention, the weight stack spring 114 has a known characteristic, ks, that relates the spring displacement, x, and the spring force, Fs, according to the following equation:
F
s
=k
s
x (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 ks 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, ks, 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 ks 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.
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
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
Referring now also to
k
c
=n*k
s (EQ 2)
The position sensor 200 produces a first sense voltage SV0, representing a first position WS0 of the sensor moving member 250, relative to the position sensor stationary member 210. Referring to
The sense voltage SV may be used to determine the amount of weight lifted off of the stack 110. Referring to
F=k
c
*x
e (EQ 3)
M
wsl
=M
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/s2 at the surface of the earth. In EQ 4 the weight stack mass Mws is the mass supported by the springs 114. Depending on the design of the incremental weight selector assembly 150, the weight stack mass Mws may also include the mass of the incremental weights 152 and or the assembly 150. To reiterate, the combined spring constant, kc, 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.
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 kc and the corresponding sensor displacement (WS1−WS0) is calculated by the electronics unit 300. In
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.
Referring to
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.
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
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.
Referring to
Referring again to
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.
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.
In an alternative embodiment 500′ of an incremental sensor according to the present invention, referring to
In
Referring to
Referring now to
M
tot
=M
wsl
M
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.
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.
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.
Number | Date | Country | |
---|---|---|---|
61931679 | Jan 2014 | US |