Abstract:
An apparatus for measuring the power generated by a person who is performing physical activity and displaying a readout of such measurement to the user. The apparatus senses and measures the motion of a mass that the person is moving and/or working against, derives position, velocity, and acceleration data and calculates power. The person thereby gains benefit of such information in real time.

Description:
This application claims the benefit of Provisional Application 60/107906 filed Nov. 10, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention generally relates to the measurement of the power generated by a person who is performing a physical activity. More specifically, the present invention pertains to the detection, measurement and display, in real time, of the peak power generated by, for example, an athlete or a physical therapy patient. 
     Many physical training professionals favor training regimens that emphasize quick, explosive movements that maximize the recruitment of fast twitch muscle fiber, with either weight training machines or free weights. It is believed that such training would be even more effective it the athlete or patient were to be instantaneously aware of his or her peak power output. 
     It is conceivable that a process that directly measures a person&#39;s neuromuscular activity could be employed to generate such information, but the rather esoteric and expensive medical laboratory devices that would be needed are cost prohibitive. Moreover, the complexity of such systems and the need for a trained technician to operate such systems renders such approach impractical for use in a weight training gym environment. 
     An alternative approach involves the detection and measurement of the motion that is imparted to a mass by an individual and then calculating the peak power that is required to achieve such motion. Use of accelerometers that are attached directly to free weights or machine weight stacks may be employed to generate such data, but such accelerometers are expensive, fragile, and susceptible to offset errors that can quickly accumulate to yield intolerable inaccuracies. 
     An improved power measuring apparatus is therefore needed that is capable of providing a real time measurement of the power generated by a person. Such apparatus must be inexpensive to manufacture, must be simple to use, must provide accurate information, and must be sufficiently durable for use in a gym-type environment. 
     SUMMARY OF THE INVENTION 
     Briefly, and in general terms, the present invention provides a new and improved apparatus for measuring and displaying power generated by a person who is performing a physical activity. More specifically, the apparatus senses and measures the motion of a mass such person is moving and/or working against, by deriving position, velocity, acceleration, calculating power, and displaying one or more such values by means of a display screen. The present invention may be incorporated in any number of physical training devices including free weights and universal gym equipment. 
     The apparatus will be utilized in situations where the power generated by a person performing physical activity is desired to be known. Such situations may include, but are not limited to, athletic weight training, sports medicine, body building, power lifting training, personal physical evaluation, physical rehabilitation, and personal fitness exercise. 
     In general terms, the apparatus of the present invention consists of a sensor/transducer that generates a signal as a function of the position of a weight being lifted by the user. Such signal is then transmitted to a computer where the power needed to achieve a sensed change in position is calculated. The calculated value is then displayed to the user. 
     Examples of a sensor/transducers adaptable to the present invention include but are not limited to cable extension potentiometers, accelerometers, linear velocity transducers (LVT), linear variable differential transformers (LVDT), ultrasonic, microwave, infrared, laser, magnetic, video and/or radio frequency position, velocity, and/or acceleration sensor/transducers. The output may be in the form of analog and/or digital data. 
     Examples of the computer used to convert the sensor/transducer signal into meaningful information may include, but are not limited to, dedicated single purpose digital computers, general multipurpose digital computers, operational amplifier-based analog computers, hybrid analog/digital computational circuits, and/or digital signal processors (DSP). The methodology for deriving and/or computing position, velocity, acceleration, and power data may consist of, but is not limited to, analog differentiation, and/or integration circuitry, and/or computational methods including, but not limited to, digital signal processing, Fourier transform analysis, wavelet theory analysis, least squares, and/or other curve fitting analyses, and/or frequency spectrum analysis. 
     Examples of the display device for communicating the calculated information to the user include, but are not limited to, cathode ray tube (CRT), liquid crystal display (LCD), light emitting diode (LED), oscillograph, printer, and/or video projection devices. The display format utilized by such display device may include, but is not limited to, numerals, bar graphs, oscillographic data, and/or audio output including signal tones and/or recorded voice. 
     More particularly, the apparatus of the present invention may take the form of a cable extension potentiometer that is physically attached to a free weight or a universal weight machine. The potentiometer sends an analog voltage signal to a set of operational amplifiers that function to break down the signal into position, velocity, and acceleration data in the form of analog voltage. The analog voltage is then digitized with a 12 bit analog to digital converter. The digital computer then calculates power which is then be related to the user along with other relevant information such as position, velocity, and acceleration. 
     These and other features and advantages of the present invention will become apparent from the following detailed description of a preferred embodiment which, taken in conjunction with the accompanying drawings, illustrates by way of example the principles of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates the various components of a preferred embodiment of the present invention; 
     FIG. 2 is an enlarged cross-sectional view taken along lines  2 — 2  of FIG. 1; 
     FIG. 3 is a cross-sectional view taken along lines  3 — 3  of FIG. 2; 
     FIG. 4 is a circuit diagram showing a preferred manner of processing the raw signal generated by the sensor; 
     FIG. 5 is a chart illustrating the data handling capability of the computer of the present invention; 
     FIG. 6 is an elevation of the computer and display screen of the present invention; 
     FIG. 7 illustrates the preferred format of a data card employed in the operation of the system of the present invention; 
     FIG. 8 illustrates a portion of a split screen display showing peak power in a numerical format; 
     FIG. 9 illustrates a portion of a split screen display showing power generation in an oscillographic format; 
     FIG. 10 illustrates a screen showing power output in a graphic format; 
     FIG. 11 illustrates an alternative embodiment of the present invention in use on a weight machine; and 
     FIG. 12 illustrates another alternative embodiment of the present invention in use on a weight machine. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The figures generally illustrate preferred embodiments of the present invention. The apparatus interfaces with weights being manipulated by a user and calculates the power being generated. Such feedback can assist a user in maximizing or optimizing his efforts. 
     FIG. 1 illustrates the general layout of a preferred embodiment of the present invention. In the example illustrated, the apparatus is associated with a free weight that the user is lifting. The apparatus includes a sensor  12  that senses the position of the weight  14  and generates corresponding electrical signals. A physical interconnection between the weight and the sensor may take the form of a cable  16  that is hooked to the weight. The signals generated by the sensor are transmitted via signal cable  18  to a computer  20  that calculates various parameters of interest. A display screen  22  presents the relevant information to the user. 
     FIG. 2 is a cross-sectional view of the sensor  12  shown in FIG.  1 . The cable  16  extends into a housing  24  through eyelet  25  where it is wound about a receiving spool  26 . The spool is fitted about an axle  28  which in turn is rotatably supported by support elements  30  and  32 . The distal end of the axle has an external thread  34  formed thereon which cooperates with an internal thread formed within support element  32  to axially shift the drum slightly as it is rotated. At its proximal end, the axle is coupled to a transducer in the form of a potentiometer  36 . A fixed vane  37  extends from the potentiometer that is slidably received in a grooved block  39  so as to prevent any rotation of the potentiometer yet allow for the slight axial displacement induced by rotation of the threaded axle in the threaded support. Alternatively, the coupling  38  may be configured to accommodate such axial movement. The potentiometer generates an analog signal as a function of its rotational position. 
     FIG. 3 is another cross-sectional view showing the internal configuration of the sensor  12  and more particularly illustrates the position of a tension reel  40  by which a slight amount of tension is maintained on cable  16  to cause it to be properly wound onto the receiving spool  26  as the weight  14  is lowered. The tension reel is rotatably supported by a pair of support elements  42  and is operatively interconnected with the receiving spool by a tension cable  44 . The tension reel is spring loaded so as to provide sufficient tension to ensure the proper paying out and take-up of cable  16  yet not interfere with the manipulation of the weight  14  in any way. 
     FIG. 4 is a basic circuit diagram illustrating how the output from potentiometer  36  may be processed within the computer  20  to provide an analog signal corresponding to the position  46 , velocity  48 , and acceleration  50  of the weight  14 . The diagram shows the use of seven operational amplifiers to differentiate position, velocity, and acceleration data from the voltage signal received via conduit  18 . FIG. 5 illustrates the flow of the analog data into the data processor  52  where it is digitized by a 12 bit analog to digital converter. The resulting data is then used by the computer in conjunction with preprogrammed data to calculate power by the formula P=M(1+A)(V) wherein M=the mass being lifted, A=acceleration of the mass in g&#39;s and V=velocity. 
     As is illustrated in FIG. 5, the computer  20  may be configured to provide versatility beyond merely displaying the calculated power on the display screen  22 . Information can be displayed on a CRT monitor  22  or an alphanumeric display  54  and/or any such information can be printed  56  or stored on either a floppy disk  58  or hard disk  60 . The storage disks may also be accessed to retrieve prerecorded data or an audio/visual record. Alternatively, an audio signal may be conducted to a speaker via port  62 . The system can additionally be networked through port  64  and an RF/IR data link  66  is provided for alternative data transmission capability. 
     FIG. 6 illustrates a preferred embodiment of the control panel for the computer  20  shown in FIG.  1 . Such illustration demonstrates the capabilities of a computer that may advantageously be employed in practicing the present invention. The control panel includes a plurality of pushbuttons, displays, a keypad, card readers and access to a floppy disk drive, which greatly enhances the overall utility of the system in a user friendly manner. 
     Operations Manual: Pressing button  72  causes sound and video to be heard and displayed on the computer monitor  22  that explains the operation of the system. Topics include (A) Setting up the system and the position transducer, (B) Function of each item on the front and back panels, (C) Proper maintenance and storage of the apparatus. This video is stored on the hard disk drive  60  in a compression format. This button is disabled if a numeric-only output display is being used instead of the computer monitor. 
     Training Manual: Pressing button  74  causes sound and video to be heard and displayed on the computer monitor  22 , that explains the proper method to perform a particular weight lifting exercise. The exercise to be demonstrated and explained is chosen by inserting the appropriate Exercise Identification Card, an example of which is illustrated in FIG. 7, into the Exercise ID card Slot  106 . This video is stored on the hard disk drive in a compression format. The button is disabled if a numeric-only output display is being used instead of the computer monitor. 
     System Display Screen: Alphanumeric screen  76  displays pertinent information regarding the status of the computer system&#39;s operations. The primary use of this screen however is to display and verify the name of the exercise selected when the Exercise Identification Card is inserted into the Exercise ID Card Slot  106 . The display can be LED, LCD or fluorescent screen of one to three rows with eight to 40 characters per row. 
     Numeral and Power/Time Graph: Pressing button  78  causes a split screen display on the computer monitor  22 . The upper half of the screen displays peak power, being generated by the person performing a weight lifting exercise in four digit numeric format. An example of such displayed information is shown in FIG.  8 . The lower half of the screen displays power, being generated by the performing a weight lifting exercise in a continuous, real time oscillographic line-graph format. An example of such displayed information is shown in FIG.  9 . The Y axis of this graph is relative power being generated, while the X axis of this graph is elapsed time. Only the numeric peak power data, displayed on the upper half of the screen, is available if a numeric-only display is being used instead of the computer monitor. 
     Power/Position Graph: Pressing button  80  causes an X-Y graph to be displayed on the computer monitor. An example of such display is shown in FIG.  10 . The Y axis of this graph is relative power being generated, while the X axis of this graph is the vertical position of the weight being lifted by the person performing a weight lifting exercise. This graph reveals the power being generated, by the person, over his/her range of motion. The X and Y axes can be switched to display vertical position of the weight on the Y axis, while relative power output is displayed on the X axis. This button is disabled if a numeric-only output display is being used instead of the computer monitor. 
     Numeral Reset: Pressing button  82  causes the numeric peak power value, of the computer monitor and/or the numeric-only display, to be set to zero. 
     Graph Reset: Pressing button  84  causes a blank screen in both the Power/Time Graph and the Power/Position Graph displays. (The X-Y coordinate lines and associated labels remain intact, but the data lines are erased.) This button is disabled if a numeric-only output display is being used instead of the computer monitor. 
     History: Pressing button  86  causes a bar chart and/or line graph to be displayed on the computer monitor. The X axis of this chart displays dates in month/day format, while the Y axis displays peak power achieved, by a person, for a particular weight lifting exercise on the date shown on the X axis. The data required to create this chart is obtained from the following sources: (A) Month/day data is obtained by the computer&#39;s internal system clock, (B) The particular weight lifting exercise is recognized and obtained by the data encoded on the Exercise Identification Card when inserted into the Exercise ID Card Slot  106 , (C) Data regarding historical peak power achieved is obtained from the person&#39;s Personal Data Disk that has been inserted into the floppy disk drive  108 . This button is disabled if a numeric-only output display is being used instead of the computer monitor. 
     Pause: Pressing button  88  causes the computer program to suspend processing. Specifically, this stops the progression of the X axis, showing elapsed time in the Power/Time Graph, enabling easier inspection of the graphed data line for analysis purposes. Pressing this button an additional time, causes the computer program to resume processing. 
     Save: Pressing button  90  causes the current peak power data, generated by the person performing a weight lifting exercise, to be copied to the person&#39;s Personal Data Disk that has been inserted into the floppy disk drive  108 . Specifically, the person&#39;s current peak power, weight lifting exercise being performed, and date are copied to a unique file that is identified by these three data inputs. This file system architecture is necessary to enable creation of a historical performance chart when the History button is pressed  86 . 
     Power Output: Switch  92  allows Horsepower, Foot Pounds Per Second, or Watts to be selected as the unit of measurement of peak power, generated by the person performing a weight lifting exercise, to be shown on the numeric displays. As a reference, one horsepower is equal to 550 foot pounds per second and approximately equal to 746 watts. 
     Weight: Switch  94  allows Pounds or Kilograms to be selected as the measurement of weight used by the computer, to calculate peak power generated by the person performing a weight lifting exercise. As a reference, one kilogram is approximately equal to 2.2046 pounds. 
     Graph Gain: Switch  96  allows a scaling factor to be selected for the power data displayed in graphical form. The lower range reduces the height of the displayed data and the upper range increases the height. This in turn, allows the graph to be tailored to individual differences in power-output. For example, a lower gain would be selected for persons generating high levels of peak-power, while a higher gain would be selected for those generating lower levels of peak power. 
     Weight Selection Display: Three digit display  98  shows the weight selected by the numeric keypad  100 . This display is an LED, LCD or fluorescent 7-segment type. 
     Data Entry: Keypad  100  allows the entering of weight data. The value entered would correspond with the amount of weight being lifted by the person performing an exercise. Shown in the front panel diagram is a 10 key numeric entry pad. However, three 10 position rotary switches may be used to enter the weight data in place of the 10 key entry pad. 
     Clear: Pressing button  102  causes the weight value shown on the Weight Selection Display  98  to be set to zero. Any changes in the weight being lifted by the person performing an exercise, will result in first clearing the old weight value by pressing this button and second, entering the new weight value with the keypad  100 . 
     Enter: Pressing button  104  causes the weight value, entered via keypad  100  and shown by the display  98 , to be entered into system memory. This weight value is one of several parameters necessary for the computer to calculate the power being generated by the person performing a weight lifting exercise. 
     Exercise ID Card: Inserting an Exercise Identification Card (shown in FIG. 7) into this slot  106  causes the unique code for a particular weight lifting exercise to be entered into system memory. In addition, the name of the exercise will be shown on the System Display Screen  76 . Each exercise in a weight lifting facility will have an associated Exercise Identification Card. Identification of the exercise will enable the system computer to: A: Select and display the appropriate training video segment when the Training Manual button  74  is pressed, B: Select the appropriate data files, from a person&#39;s Personal Data Disk, to create a history graph when the History button  86  is pressed, C: Along with date information, create appropriate data files, on the person&#39;s Personal Data Disk when the Save button  90  is pressed. 
     Floppy Disk Drive: The disk drive  108  is primarily used to read data from and write data to a person&#39;s Personal Data Disk. The Personal Data Disk contains peak power data for each day a person performs particular weight lifting exercises. For example, if a person performs 12 different weight lifting exercises on each of 60 different days, the Personal Data Disk will contain 360 peak power data points (12 exercises×60 days=360). Additionally, this drive is used to update the computer system with new software releases. 
     FIG. 11 illustrates the present invention adapted for use in a commonly used weight machine. The cable  16  extending from sensor  12  is attached to the pin  110  by which the stack of weights  112  to be lifted is engaged. When a user lifts the selected weight by pulling down on handles  114 , the cable  16  is pulled out of sensor  12 . The position of the weight is thereby sensed by sensor  12  which generates an electrical signal that is transmitted to computer  20  via cable  18 . The signal is processed to provide a measure of the power being generated by the user which is displayed to the user on display screen  22 . 
     FIG. 12 illustrates the present invention adapted for use in another commonly used weight machine. The cable extending from the sensor  12  is attached to weight  114  and the signal generated by the sensor is transmitted to the computer  20  via cable  18 . This particular embodiment shows a small display screen  22   a  attached to a flexible support arm  116  positioned where the user can readily see it. Such screen may take the form of an alphanumeric display showing only a read out of the power figures. 
     While a particular form of the present invention has been illustrated and described, it will also be apparent to those skilled in the art that various modifications can be made without departing from the spirit and the scope of the present invention. More particularly, the present invention may be adapted to measure the power generated in manipulating substantially any of the multitude of weight training devices currently in use. Additionally, the sensor need not be limited to a cable extension potentiometer but may take the form of other sensor/transducers including, but not limited to an accelerometer, linear velocity transducer (LVT), linear variable differential transformer (LVDT), ultrasonic, microwave, infrared, laser, magnetic, video and/or radio frequency position, velocity, and/or acceleration sensor/transducers. The output of such devices may be analog or digital. The signal generated by such devices may be transmitted to the computer via wire, optic fiber, or via RF, IR, or microwave transmission or by ultrasonic methods. The computer may take the form of any of a number known devices, not just limited to dedicated single purpose digital computers, but may take the form of general purpose digital computers, operational amplifier-based analog computers, hybrid analog/digital computational circuits, and/or digital processors (DSP). The methodology for deriving and/or computing position, velocity, acceleration, and power data consists of one or more various known technologies including, but not limited to, analog differentiation and/or integration circuitry and/or digital computational methods including, but not limited to, digital signal processing, Fourier transform analysis, wavelet theory analysis, least squares and/or other curve fitting analyses and/or frequency spectrum analysis. The display need not be limited to a CRT device, but may include LCD, LED oscillograph, printer, and/or video projection devices. The display format utilized by such device may include numerals, bar graphs, oscillographic data, seven segment and/or other LEDs and /or audio output including signal tones, and/or recorded voice. Accordingly, it is not intended that the invention be limited except by the appended claims.