Automatic spotter lift force calculator and display device and method of use

A system for measuring actual weight lifted by a user when a spotting force is applied and calculating a spotting force. The system is comprised of a display device and sensors having strain gauges attached to a weight lifting bar. The system will determine and display the actual weight lifted by a user with or without a spotting force, and a spotting force applied.

FIELD OF THE INVENTION

The present invention relates to the measurement of variable forces acting on a weight machine during exercise.

BACKGROUND OF THE INVENTION

Free weights, such as dumbbells and barbells, are frequently used in training programs to increase strength and endurance. However, traditional weight lifting techniques using free weights often require a spotter to assist when muscle fatigue occurs. The need for a spotter presents a significant problem for weightlifters because it limits the ability to work out alone. The need for a spotter also creates a problem for weightlifters because the amount of weight lifted by the spotter is largely unknown during a workout.

To address these problems, many different types of exercise machines have been developed which use cable or pulley systems coupled with a weight slack. Such exercise machines provide the ability to perform various exercises without requiring a spotter.

For example, the invention disclosed in U.S. Pat. No. 9,138,612 to Breaux describes a multi-station exercise machine which includes a slack adjuster or “spotter” mechanism. The invention disclosed allows a user experiencing muscle fatigue to engage a different set of muscles to relieve the weight being lifted, or “self-spot”.

Referring then toFIG.1, multi-mode exercise machine100as known in the prior art is shown in the incline press configuration.

In the incline press configuration, upper support beam102is connected to vertical frame post101which is connected to lower support beam104. Seat103is supported by vertical frame post101and post135. Spotter extension106is connected to the seat at axis107. Spotter extension106includes padded cross bar108.

Lower support beam104is further connected to vertical post105. Vertical post105includes free weight cradle112. The cradle supports a barbell when it is not being lifted by a user.

Pulley116is operatively connected to upper support beam102. Spotter cable111extends through a series of pulleys, such as pulley116, connected to the support frame. Spotter cable111connects to spotter extension106via pin connector109. Spotter cable111includes bar clamp110which attaches to the center of a barbell.

In use, when muscle fatigue is felt by a user, spotter extension106is rotated away from the user along axis107by exerting force on padded cross bar108. Spotter cable111is retracted thereby lifting a barbell attached via bar clamp110and relieving the weight supported by the user.

Referring then toFIG.2, an alternate multi-mode exercise machine101as known in the prior art is shown in the preacher curl configuration.

In the preacher curl configuration, upper support beam102is connected to vertical frame post101which is connected to lower support beam164. Upper support beam102is supported by support brace115connected to vertical frame post101. Seat103is supported by vertical frame post101and “U”-shaped post105. Post105includes free weight cradle112. Angled post217is connected to post105. Angled post217includes padding151.

Spotter extension106is connected to the seat at axis107. Spotter extension106includes padded cross bar108.

Pulley116is operatively connected to upper support beam102. Pulley123is operatively connected to lower support beam164. Spotter cable111extends through a series of pulleys, such as pulley116and pulley123, connected to the support frame. Spotter cable111connects to spotter extension106via pin connector109. Spotter cable111includes bar clamp110which attaches to the center of a barbell.

In use, when muscle fatigue is felt by a user, spotter extension106is rotated away from the user along axis107by exerting force on padded cross bar108. Spotter cable111is retracted thereby lifting a barbell attached via bar clamp110and relieving the weight supported by the user.

However, the prior art fails to address the problems of measuring the weight lifted by the spotter. Thus, both the actual weight lifted and the spotter force applied by the weightlifter are unknown. This creates a problem because competitive weightlifters need to know the exact amount of weight lifted and the exact amount of the spotter force.

The prior art has attempted to provide a solution to the existing problems. But all have fallen short.

For example, WO Publication No. 2021/0745615 to Hollier discloses an exercise system which displays an upward force exerted on an anchored resistance device. The exercise system described in '615 to Hollier measures the tension force. No external variable force, such as a spotter, is used to relieve muscle fatigue with resistance training. When muscle fatigue occurs, the user simple exerts less force on the resistance device. Therefore, the device does not measure an external and variable spotter force.

As another example, U.S. Pat. No. 4,647,038 to Noffsinger discloses a system for measuring forces exerted between a handgrip and a barbell. The handles are enclosed around the bar and include strain gauges on opposite sides of the bar. Thus, the system will display only one force exerted on the bar, the force downwards, but will not measure an external and variable spotter force.

Thus, there is a need for a weight measuring device that determines and displays the original weight, the spotter force and the resulting weight lifted.

DETAILED DESCRIPTION OF THE INVENTION

In the description that follows, like parts are marked throughout the specification and figures with the same numerals, respectively. The figures are not necessarily drawn to scale and may be shown in exaggerated or generalized form in the interest of clarity and conciseness.

Referring then toFIG.3, the configuration of a barbell with a preferred embodiment of a weight display device attached will be described.

Barbell300is comprised of steel shaft302. Steel shaft302is typically about 5 to 7 feet long having a diameter of approximately 1 inch. The steel shaft includes grip308and grip310. Grips308and310are typically knurled sections of the bar.

Barbell300is further comprised of sleeve304and sleeve305. Sleeve304is connected to end301of steel shaft302. Sleeve305is connected to end303of steel shaft302. The sleeves are chrome cylinders coaxial with the steel shaft having a diameter of about 2 inches. Sleeve304includes integrally formed collar309. Sleeve305includes integrally formed collar311.

In a preferred embodiment, sleeves304and305include bearings321and bearings322. The bearings allow rotation of the sleeves around steel shaft302to reduce friction on the users hands as the bar is rotated about its longitudinal axis. Sleeve304and sleeve305support weight plate306and weight plate307, respectively.

Connected to barbell300are sensor312, sensor314, and display device316. Display device316is comprised of a screen and microcontroller, as will be further described. The display device is positioned off-center on the barbell. In a preferred embodiment, the display device is removably attached to the steel shaft via clip317. Alternative methods of attaching the display device may be utilized.

Sensor312and sensor314each include a strain gauge and are electrically connected to display device316, as will be further described. In a preferred embodiment, the sensors are removably attached to the steel shaft along grip lines using a suitable industrial adhesive. In alternate embodiments, a single strain gauge may be employed, at either position.

Barbell300may be used with the multi-mode exercise machine disclosed in '612 Patent to Breaux. In this configuration, bar clamp318attaches spotter cable320to barbell300at center line350.

It should be noted that while the invention is shown in use with a barbell, it may also be used with other lifting bars or a multi-mode weight lifting machines, such as a trap bar, a log bar, a Swiss bar, a safety squat bar, a cambered bar, a curl bar, or a tricep bar.

Referring then toFIG.4A, an example free body diagram400representing the forces exerted on barbell300during use will be further described.

In any static situation, the sum of the forces on the free body must equal zero. In this example, lift forces LF1and LF2are directed upwards on sensors312and314. LF1+LF2is equivalent in magnitude, but opposite in direction to the weight of the bar and weights which acts with a downward force W. When a central spotting force, SF, is applied, the free body diagram must still be in equilibrium. Therefore, the sum of forces exerted may be represented by the following equation:
LF1+LF2+SF−W=0

In this example it is assumed that LF1=LF2. However, it should be appreciated that while the spotting force is depicted as central to the barbell, a spotting force may be applied at one or more positions, such as at either end of the bar. Further, these spotting forces may not be equal. In this case, LF1may not be equal to LF2and so the sensors will measure different force values.

Those of skill in the art will recognize that the forces described may be reversed, such as in the case where the lift force is directed downward, such as in a typical trap exercise on a trap machine.

Referring then toFIG.4B, an example of free body diagram401, representing different forces exerted on barbell300during use, will be further described.

In this example, lift forces LFL and LFR are directed upwards on sensors312and314. Spotting forces SFL and SFR are directed upward. Weight force W, as a result of gravity, is directed downward.

Force LFL acts at distance d1from force SFL. Weight force W acts at distance d2from SFL. Force LFR acts at distance d3from SFL. Likewise, force SFR acts at distance d4from force SFL.

Forces W, LFL and LFR are known. Force W is the total weight of the free weights and the bar combined. Force LFL and LFR are available from force sensors312and314, as will be further described.

Assuming the known variables, the following equations of motion apply.
ΣF: SFL+LFL+LFR+SFR+W=0
ΣM: SFL(0)+LFL(d1)−W(d2)+LFR(d3)+SFR(d4)=0
Where:d1=the distance between the application point of SFL and LFL;d2=the distance between the application point of SFL and bar center;d3=the distance between the application point of SFL and LFR; and,d4=the distance between the application point of SFL and SFR.

Referring then toFIG.5A, a schematic of a preferred embodiment of display device500will be further described.

Display device500is comprised of strain gauge518and strain gauge520electrically connected to analog amplifier516. Strain gauges518and520are located in sensors312and314. In a preferred embodiment, analog amplifier516is a high precision load cell weight sensor having two channel input and capable of providing a digital output, such as the HX711 by Avia Semiconductor of China.

Analog amplifier516is further connected to microcontroller508. Battery502is connected to display506, microcontroller508and analog amplifier516through voltage regulator504. In a preferred embodiment, display506is a low power LCD, or a super twisted nematic LCD, such as part no. NHD-0208AZ-RN-YBW-33 available from Newhaven Display Intl of Elgin, Illinois. However, alternative screen types may be used, such as LED or OLED.

Microcontroller508is comprised of processor510, memory512, and communication interface514. Memory512includes an operating system for the micro controller and a set of program instructions, which, when executed by the microcontroller, carry out the functions of the invention. In one embodiment, communication interface514includes Bluetooth capabilities to connect with a wireless device, such as a smartphone, as will be further described.

Microcontroller508is also operatively connected to keypad513. In a preferred embodiment, keypad513is a compact alphanumeric keypad, such as keypad switch GS120203 by Storm Interface of Maldon, England.

Referring then toFIG.5B, a network diagram for an alternate embodiment of a system incorporating the display device will be further described.

Display device500is wirelessly connected to client device530. Client device530is a smart device such as a smartphone or tablet. In a preferred embodiment, client device530includes application532which when activated connects the client device to display device500via Bluetooth. Client device530further comprises onboard display533which is controlled by application532. In this embodiment, data indicating the actual weight, the spotter force and the resultant weight lifted are sent to the client device wirelessly where they are stored and displayed.

Referring toFIG.6A, preferred a mode selection state chart will be further described.

At system start-up, microcontroller508enters wait state605. During wait state605, microcontroller508monitors keypad513for entry of a state selection.

In a preferred embodiment, two-state selections are available, system startup state601and run state603.

Upon selection of system startup state601, the processor polls the keypad for data entry, as will be further described. On completion of system startup state601, the processor returns to wait state605.

Upon selection of run state603, the processor loads and executes a set of instructions that carry out the functions of the device, as will be further described. Upon completion of run state603, the microcontroller returns to wait state605.

Referring toFIG.6B, run state603will be further described.

At step602, a force is applied to the bar on each of the left and right sensors.

Steps604through608are optional, and are carried out only if, during setup, no total weight amount is entered.

At optional step604, the processor reads sensor activity.

At optional step606, the processor delays for about five seconds, in order to allow sufficient time for the force on the bar to stabilize between the right and left sensors. Other delay times may be used.

At optional step607, the processor reads both right and left sensors from the analog amplifier and converts them to a digital weight measurement value.

At optional step608, the processor stores the original weight values for each of the right and left sensors.

At step610, a spotter force or spotter forces are applied to the bar.

At step611, the processor then again reads the sensor activity.

At step612, the processor again delays about five seconds in order to allow the spotter forces to stabilize. Other delay times may be used.

At step614, the processor again reads the right and left sensors from the analog amplifier and converts them to a digital weight measurement value.

At step615, the processor stores resultant weight values for each of the left and right sensors.

At step616, the processor calculates the spotter forces and the left and right lifting forces as may be required. In a preferred embodiment, the following equations are computed to determine the amount of weight lifted with no spotter forces applied.
LFL1+LFR1=LFTOTAL
Where:LFL1=left sensor value as weight is lifted with no spotter forces applied;LFR1=right sensor value as weight is lifted with no spotter forces applied; and,LFTOTAL=original weight lifted.

The following equations are computed to determine the spotter force applied.
LFL2+LFR2=LFRESULTANT
Where:LFL2=left sensor value after spotter force is applied;LFR2=right sensor value after spotter force is applied; and,LFRESULTANT=the resulting weight lifted after application of the spotter force.
LFSPOTTER=LFTOTAL−LFRESULTANT
Where:LFSPOTTER=spotting force.

In situations where there are more than one spotting force is applied and the lifting and spotting forces at the sensors differ, the following equations are computed:

The following equations are computed to determine the spotter forces applied:

At step620, the processor sends a signal to the display to indicate the original weight lifted.

At step622, the processor sends a signal to the display to indicate the total spotter force. In another embodiment, spotter force for each of the left and right sensors is displayed.

At step624, the processor sends a signal to the display to indicate the resultant weight lifted. In another embodiment, the resultant weight lifted at each of the left and right sensors is displayed.

At step626, optionally, the processor transmits the display data to the smartphone via communication interface514.

At step628, the smartphone receives the display data through its own communication interface and displays it via application532.

At step630, the processor returns to mode selection.

Referring then toFIG.6C, system startup state601will be further described.

At step650, processor510polls keypad513for an entry of the total weight of the bar and the weight plate to be lifted by the user.

At step654, the processor returns to wait state605.