Abstract:
A training method and apparatus for improving a physical technique, action, move or routine includes a portable electronic device which may be unobtrusively worn by the user. The portable electronic device includes motion sensor such as an accelerometer and/or gyroscope to determine the orientation and movement of the device. By monitoring the output of the motion sensor and applying the values according to predetermined movements, the user may be immediately provided positive and negative feedback. The device may be worn by the user during exercise or a sporting event without interfering with the user&#39;s movement.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of co-pending application Ser. No. 61/376,096, filed on Aug. 23, 2010, entitled TRAINING AID. 
     
    
     FIELD 
       [0002]    The present invention relates to training aids and, more particularly, to an electronic training aid for physical activity which provides concurrent feedback to the user. 
       BACKGROUND 
       [0003]    Training aids for physical activities such as sports or exercise routines are known in the art. Some of these aids force the user to repetitively follow a particular motion to learn the proper technique. These aids often require normal equipment apart from the training aid equipment used to guide or restrict the user during training. Other training aids are used in place of the normal equipment, such as a baseball bat or golf club. While these aids may be beneficial while practicing, they cannot be used when participating in the activity. Additionally, some training aids are not physically practical and may not be allowed when participating in the activity, resulting in a disconnect between the training session and the session for which the training is directed, such as a round of golf. Further, the training aids are often just that—training aids. They are specialized devices or pieces of equipment that are not particularly useful for anything else. Once a practice or training session is complete, the training equipment or aid must be set aside or stored until used again for training. 
         [0004]    Other training aids require expensive equipment such as video cameras, video manipulation, interpretation and analysis, software and specialized equipment. One such system is a golf swing analyzer utilizing a high speed video recording system. The user is videoed from one or more angles while swinging a golf club. A golf professional or coach may observe a user while recording a series of golf swings. The user and golf professional may then view the recorded video to identify problems, poor techniques and areas for improvement. While this system is useful and effective while in the training studio with the instructor, it provides no feedback to the user in the native environment of the exercise routine or sport. Further, these training aids are costly, require technical expertise to use and require scheduling and planning. 
       SUMMARY 
       [0005]    The present invention provides a training method and apparatus for improving a physical technique, action, move or routine. The training method and apparatus includes a portable electronic device which may be unobtrusively worn by the user. The portable electronic device includes a motion sensor such as an accelerometer and/or gyroscope to determine the orientation and movement of the device. By monitoring the output of the motion sensor and applying the values according to predetermined movements, the user may be immediately provided positive and negative feedback pertaining to the proper physical technique, action, move or routine. The device may be worn by the user during exercise or a sporting event without interfering with the user&#39;s movement. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  illustrates a coordinate system for a portable electronic device. 
           [0007]      FIG. 2  illustrates angular readings for various orientations of the electronic devices of  FIG. 1  in the X-Y plane. 
           [0008]      FIG. 3  illustrates the angular readings for various orientation of the electronic device of  FIG. 1  in the X-Z plane. 
           [0009]      FIG. 4  illustrates the angular readings for various orientations of the electronic device of  FIG. 1  in the Y-Z plane. 
           [0010]      FIG. 5  illustrates the electronic device positioned to measuring a putting movement. 
           [0011]      FIG. 6  illustrates the electronic device positioned to measure a stroke movement. 
           [0012]      FIG. 7  illustrates the electronic device positioned to measure a head movement. 
           [0013]      FIG. 8  illustrates the electronic device positioned to measure hip movement. 
           [0014]      FIG. 9  is a flow chart illustrating the initial function selection. 
           [0015]      FIG. 10  is a flow chart illustrating the putting motion algorithm. 
           [0016]      FIG. 11  is a flow chart illustrating the shoulder turn/rotation algorithm. 
           [0017]      FIG. 12  is a flow chart illustrating the head motion algorithm. 
           [0018]      FIG. 13  is a flow chart illustration the hip turn algorithm. 
           [0019]      FIG. 14  is a flow chart illustrating an initial exercise algorithm. 
           [0020]      FIG. 15  is a flow chart illustrating the sit-ups algorithm. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    As required, detailed embodiments of the present invention are disclosed herein. However, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale, some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for the claims and/or as a representative basis for teaching one skilled in the art to variously employ the present invention. 
         [0022]    Moreover, except where otherwise expressly indicated, all numerical quantities in this description and in the claims are to be understood as modified by the word “about” in describing the broader scope of this invention. Practice within the numerical limits stated is generally preferred. Also, unless expressly stated to the contrary, the description of a group or class of materials as suitable or preferred for a given purpose in connection with the invention implies that mixtures or combinations of any two or more members of the group or class may be equally suitable or preferred. 
         [0023]    Referring initially to  FIGS. 1-4 , a training aid is generally indicated by reference numeral  20 . Training aid  20  is a portable, electronic device which includes one or more motion sensors such as a three-axis accelerometer  22  such as a LIS302DL MEMS (micromechanical system) motion sensor available from STMicroelectronics NV, and/or a gyroscope  23  such as a L3GD20 MEMS gyroscope also available from STMicroelectronics, for example. The LIS302DL is an ultra-compact, low-power, three-axis linear accelerometer which is integrated in portable electronic devices such as the iPhone and iPod Touch available from Apple Inc. for example. Other portable electronic devices utilizing the LIS302DL accelerometer, or utilizing another accelerometer may be used with the training aid  20 . The LIS302DL accelerometer operates in a range of +/−2 g in the iPhone and iPod Touch with a nominal resolution of 0.018 g. The L3GD20 gyroscope offers a wide set of user-programmable full-scale ranges from ±250 dps (degrees per second) up to ±2000 dps, with the low full-scale values for high accuracy of slow-motion sensing and the high range to detect and measure very fast gestures and movements. The device provides a 16-bit data output, together with additional embedded digital features, such as configurable low- and high-pass filters. 
         [0024]    The training aid  20  includes a case  24  and a touch screen  26 . For illustration purposes only, the training aid  20  will be described with a touch screen  26 . However, it should be understood that devices utilizing other displays, input and selection configurations, such as a key pad, may be used. 
         [0025]    The training aid  20  includes three axes of orientation—the X-axis  28 , Y-axis  30  and Z-axis  32 . The X-axis  28  is an imaginary line running laterally through the center of the accelerometer  22 . As illustrated, the accelerometer  22  is mounted behind the touch screen  26  within the case  24  at the center of the training aid  20 . The X-axis  28  is perpendicular to the Y-axis  30  and Z-axis  32  in a horizontal plane parallel to the touch screen  26  running through the left and right sides of the training aid  20  case  24 . The Y-axis  30  is an imaginary line running vertically through the center of the accelerometer  22 . The Y-axis  30  is perpendicular to the X-axis  28  and Z-axis  32  in a vertical plane parallel to the touch screen  26  running through the top and bottom sides of the training aid  20  case  24 . The Z-axis  32  is an imaginary line running perpendicularly through the center of the accelerometer  22 . The Z-axis  32  is perpendicular to the X-axis  28  and Y-axis  30  in a horizontal plane running perpendicularly through the touch screen  26  and back of the case  24 . 
         [0026]    As the training aid  20  is moved or rotated, the accelerometer  22  outputs three values, one for each axis. For example, the X-value output of the accelerometer as the training aid is rotated in the X-Y plane is illustrated in  FIG. 2 . When the training aid  20  is in a landscape right orientation  34 , the X-output from the accelerometer  22  is 0.0. As the training aid  20  is rotated clockwise, the X-output from the accelerometer  22  increases. At an orientation of 45°  36  from the landscape right orientation  34 , the X-output of the accelerometer  22  is 0.75. At an orientation of 90°  38  from the landscape right orientation  34  the X-output of the accelerometer  22  is 1.5. At an orientation of 135°  40  from the landscape right orientation  34 , the X-output of the accelerometer  22  is 2.25. At an orientation of 180°  42  from the landscape right orientation  34 , the X-output of the accelerometer  22  is 3.0. Rotating the opposite way at an orientation of −45°  44  from the landscape right orientation  34 , the X-output of the accelerometer is −0.75. At an orientation of −90°  46  from the landscape right orientation  34  the X-output of the accelerometer  22  is −1.5. At an orientation of 135°  48  from the landscape right orientation  34 , the X-output of the accelerometer  22  is −2.25. The outputs shown in  FIGS. 2-4  are scaled examples not the raw output from the accelerometer  22 . The specific output from the accelerometer  22  is a function of the particular device and is available from the manufacturer and technical specifications. 
         [0027]    As the training aid  20  is rotated in the Y-Z plane, the Y-value output of the accelerometer is illustrated in  FIG. 3 . When the training aid  20  is in a landscape right face-up orientation  50 , the Y-output from the accelerometer is 0.0. As the training aid  20  is rotated clockwise in the Y-Z plane, the Y-output from the accelerometer  22  increases. At an orientation of 45°  52  from the landscape right face-up orientation  50 , the Y-output of the accelerometer  22  is 0.75. At an orientation of 90°  54  from the landscape right face-up orientation  50 , the Y-output of the accelerometer  22  is 1.5. At an orientation of 135°  56  from the landscape right face-up orientation  50 , the Y-output of the accelerometer  22  is 2.25. At an orientation of 180°  58  from the landscape right face-up orientation  50 , the Y-output of the accelerometer  22  is 3.0. Rotating the training aid  20  in the opposite direction at an orientation of −45°  60  from the landscape right face-up orientation  50 , the Y-output of the accelerometer  22  is −0.75. At an orientation of −90°  62  from the landscape right face-up orientation  50 , the Y-output of the accelerometer  22  is −1.5. At an orientation of −135°  64  from the landscape right face-up orientation  50 , the Y-output of the accelerometer  22  is −2.25. 
         [0028]    As the training aid  20  is rotated in the X-Z plane, the Z-value output of the accelerometer is illustrated in  FIG. 4 . When the training aid is in a landscape right face-left orientation  66 , the Z-output of the accelerometer  22  is 0.0. At an orientation of 45°  68  from the landscape right face-left orientation  66 , the Z-output of the accelerometer  22  is 0.75. At an orientation of 90°  70  from the landscape right face-left orientation  66 , the Z-output of the accelerometer  22  is 1.5. At an orientation of 135°  72  from the landscape right face-left orientation  66 , the Z-output of the accelerometer  22  is 2.25. At an orientation of 180°  74  from the landscape right face-left orientation  66 , the Z-output of the accelerometer  22  is 30. Rotating the opposite way, at an orientation of −45°  76  from the landscape right face-left orientation  66 , the Z-output of the accelerometer  22  is −0.75. At an orientation of −90°  78  from the landscape right face-left orientation  66 , the Z-output of the accelerometer  22  is −1.5. At an orientation of −135°  80  from the landscape right face-left orientation  66 , the Z-output of the accelerometer  22  is −2.25. 
         [0029]    The gyroscope  23  outputs 8- or 16-bit data at a rate of ±250 dps to ±2000 dps in each axis corresponding to pitch  29 , roll  31  and yaw  33 . From the raw data, the angular rate or velocity of the training aid  20  may be determined. 
         [0030]    Referring to  FIGS. 5-9 , use of the training aid  20  is disclosed herein by reference to movements related to golf as an example and for illustrative purposes only. The training aid  20  is not limited to detecting and providing feedback for golf movements only. One of ordinary skill in the art will readily recognize other applications for the present invention which are within the scope of this disclosure, such as exercise routines, baseball, tennis, dance, basketball, bowling, or any physical activity that includes repetitious moves for the activity or in practice or training. 
         [0031]    A user initially selects the training aid application  100  loaded on the training aid  20 . The training aid  20  includes a microprocessor or computer and computer-readable media such as RAM. The training aid application  100  includes computer-executable instructions on the computer-readable media for interpretation by the microprocessor or computer. When the training aid application  100  is executed by the microprocessor, the training aid  20  provides instructions to the user by way of the display or touch screen  26 , and feedback to the user by way of an audio or tactile output. 
         [0032]    When the training aid application  100  is initially selected by the user, the microprocessor begins execution of the application  102 , and an initial screen is displayed  104 . For purposes of providing a disclosure of the present invention, an exemplary application is described, but is not so limited. The exemplary application is related to a training aid application for golf. For this example application, the user is presented a choice of three modes of operation  106 . The user may select a putting motion mode  108 , a shoulder turn/rotation mode  110 , a head motion mode  112 , and a hip turn mode  113 . 
         [0033]    Referring to  FIGS. 5 and 10 , if the putting motion mode  108  is selected, the user  90  places the training aid  20  on his or her forearm  91  by way of a strap or other means to secure the training aid  20  to his or her forearm  91 . Once the training aid  20  is positioned on his or her forearm  91 , the user  90  taps the touch screen  26  to start the putting motion mode  114 . At this point the accelerometer  22  is started  116  and a countdown timer is started  118 . The countdown timer gives the user  90  time to get his or her hands and arms in position to practice a putting motion. While the countdown timer is running  118 , the X, Y and Z values output from the accelerometer  22  are collected  120 . If the countdown timer has not expired  122 , processing continues  124  to block  126  where it is determined if the X, Y and Z values have been stabilized, if they have not stabilized the system continues to calibrate  127  and reads another set of X, Y and Z values  120 . The X, Y and Z values are read approximately 50 times per second. 
         [0034]    Once the countdown timer expires  123 , the initial X, Y and Z values are set  128 . The values are checked to determine if they are stable  126 . If the values are not stable, the process continues to calibrate  127  and reads another set of values  120 , which are then set  128 . Once calibration is completed  129 , a motion sensor  130  monitors movement of the training aid  20 . As long as the motion is not sensed  132 , another set of values is read  120  and stored  128 . 
         [0035]    Once motion is sensed  133 , a check is made to determine if a beep timer has completed  134 . The beep timer gives the user time to complete his or her putting motion within a predetermined period of time. If the beep timer has expired  135 , then the training aid  20  outputs a negative indication in the form of an audio or tactile negative feedback and processing returns to the beginning  108 . 
         [0036]    If the beep timer is not complete  137 , the X value is compared to a lower bound X value  136 . If the X value is less than the lower bound X value  138 , then the measured acceleration was within the proper range  140 . If the X value is greater than the lower bound X value  142 , then the measured acceleration was not within the proper range  144 . This lower bound comparison may be use for right-handed putting. 
         [0037]    For left-handed putting, the X value is compared to an upper bound X value. If the X value is greater than the upper bound X value, then the measured acceleration was within the proper range. If the X value is lower than the upper bound X value, then the measured acceleration was not within the proper range. 
         [0038]    If the X value is within the proper acceleration range  140 , then the user  90  accelerated through the putt within an acceptable range of X values, and the training aid  20  outputs a positive indication in the form of an audio or tactile positive feedback. If the X value is not within the proper range  144 , then the user  90  did not accelerate through the putt within an acceptable range of X values and the training aid  20  outputs a negative indication in the form of an audio or tactile negative feedback. Processing then returns to the beginning of the putting motion mode  108 . 
         [0039]    Referring to  FIGS. 6 and 11 , if the shoulder turn/rotation mode  110  is selected, the user  92  places the training aid  20  on his or her upper arm  93  or shoulder by way of a strap or other means to secure the training aid  20  to his or her shoulder. Once the training aid  20  is positioned on his or her upper arm or shoulder  93 , the user  92  taps the touch screen  26  to start the shoulder turn/rotation mode  200 . The accelerometer  202  and countdown timer  204  are started. While the countdown timer  204  has not expired  206 , the output of the accelerometer is filtered  208 . The output of the filter is as follows: 
         [0000]        X =Accel  X *filter constant+ X *(1.0−filter constant)
 
         [0000]        Y =Accel  Y *filter constant+ Y *(1.0−filter constant)
 
         [0000]        Z =Accel  Z *filter constant+ Z *(1.0−filter constant)
 
       Where: 
       [0040]    Accel X, Accel Y and Accel Z are the X, Y, Z values output by the accelerometer  22 . 
         [0041]    Filter const=dt/(dt+RC) 
         [0042]    dt=1.0/50.0 
         [0043]    RC=1/5 
         [0044]    The filter  208  smoothes the values output by the accelerometer  22 . The new X, Y and Z values from the filter  208  are read  210 . If the countdown timer  204  has not expired  212 , processing continues  214  to block  216  where it is determined if the X, Y and Z values have stabilized. If the X, Y and Z values have not stabilized, the system continues to calibrate  216  and returns  218  to read another set of X, Y and Z values  210 . 
         [0045]    The countdown timer  204  is checked  212 , and if it has expired  213 , the initial X, Y and Z values are set  220 . If the values are not stable, the process continues to calibrate  218  and reads another set of values  210 , which are then set  220 . Once calibration is completed  222 , a motion sensor  224  monitors movement of the training aid  20 . As long as the motion is not sensed  226 , another set of values is read  210  and stored  220 . 
         [0046]    Once motion is sensed  228 , a beep timer is checked  229 . The beep timer gives the user time to complete his or her shoulder turn motion within a predetermined period of time. If the beep timer has expired  231 , then the training aid  20  outputs a negative indication in the form of an audio or tactile negative feedback and processing returns to the beginning  110 . 
         [0047]    If the beep timer is not complete  233 , a check is made to determine if the user previously selected a 60° motion or a 90° motion  230 . If the user selected a 60° motion  232 , the Y value is compared to the Z value  234 . If the Y value is greater than the Z value  236 , then a 60° turn has been measured  238  and the user  92  is given an audio or tactile positive feedback and processing returns  240  to the beginning  110 . It should be understood that the 60° turn or a 90° turn are approximate values and may be set to a range or to other values as desired such as approximately 45° for example. 
         [0048]    If the Y value is less than or equal to the Z value  242 , then at least a 60° turn has not been measured  244  and the user  92  is given an audio or tactile negative feedback. Processing then returns  240  to the beginning  110 . 
         [0049]    If the user selected a 90° motion  246 , the change in the value X is calculated as Dx=X−Y  248 . Dx is then compared to a constant  250 . If Dx is less than or equal to the constant  252 , then a 90° turn has been measured  254  and the user  92  is given an audio or tactile positive feedback. Processing returns  240  to the beginning  110 . 
         [0050]    If Dx is greater than a constant  256 , then at least a 90° turn has not been measured  258  and the user  92  is given an audio or tactile negative feed back. Processing then returns  240  to the beginning  110 . 
         [0051]    Referring to  FIGS. 7 and 12 , if the head motion mode  112  is selected, the user  94  places the training aid  20  on the side of his or her head by way of a strap, pocket  95  on his or her cap  96  or other means to secure the training aid  20  to the side of his or her head. Once the training aid  20  is positioned on the side of his or her head, the user  94  taps the touch screen  26  to start the head motion mode  300 . The accelerometer  302  and countdown timer  304  are started. While the countdown timer  304  has not expired  306 , the output of the accelerometer is filtered  308 . The output of the filter  308  is as follows: 
         [0000]        X =Accel  X *filter constant+ X *(1.0−filter constant)
 
         [0000]        Y =Accel  Y *filter constant+ Y *(1.0−filter constant)
 
         [0000]        Z =Accel  Z *filter constant+ Z *(1.0−filter constant)
 
       Where: 
       [0052]    Accel X, Accel Y and Accel Z are the X, Y, Z values output by the accelerometer  22 . 
         [0053]    Filter const=dt/(dt+RC) 
         [0054]    dt=1.0/50.0 
         [0055]    RC=1/5 
         [0056]    The filter  308  smoothes the values output by the accelerometer  22 . The new X, Y and Z values from the filter  308  are read  310 . If the countdown timer  304  has not expired  312 , processing continues  314  to block  316  where it is determined if the X, Y and Z values have stabilized. If the X, Y and Z values have not stabilized, the system continues to calibrate  316  and returns  318  to read another set of X, Y and Z values  310 . Once calibration is completed  322 , a motion sensor  324  monitors movement of the training aid  20 . As long as the motion is not sensed  326 , another set of values is read and stored  310 . 
         [0057]    Once the motion timer expires  328 , the Z value is compared to the upper bound  330 . If the Z value is greater than or equal to the upper bound  332 , then the user&#39;s head motion is acceptable. The user  94  is given an audio or tactile positive feedback  334  and processing returns  336  to the beginning  112 . 
         [0058]    If the Z value is not greater than the upper bound  338 , it is checked against a lower bound  340 . If the Z value is less than or equal to the lower bound  342  then the Y value is checked to determine if it is out of range  344 . If the Y value is not out of range  346 , then processing returns to block  310 . If the Y value is out of range  348 , then the user&#39;s head motion is not accepted  350  and the training aid  20  outputs a negative feedback to the user  94  in the form of an audio or tactile signal. Processing then returns  352  to the beginning  112 . 
         [0059]    If the Z value is not less than the lower bound  354 , then the X value is checked to determine if it is out of range  356 . If the X value is not out of range  358 , then processing returns to block  310 . If the X value is out of range  360 , then the user&#39;s head motion is not accepted  350  and the training aid outputs a negative feedback to the user  94  in the form of an audio or tactile signal. Processing then returns  352  to the beginning  112 . 
         [0060]    Referring to  FIGS. 8 and 13 , if the hip turn/rotation mode  113  is selected, the user  97  places the training aid  20  on his or her waist  99  by way of a belt or other means to secure the training aid  20  to his or her waist  99 . The system checks for a start signal  500 . If no start signal is received,  502 , the system continues to wait. Once the training aid  20  is positioned, the user  97  taps the touch screen  26  to start the hip turn/rotation mode  504 . The gyroscope is started  506  and the initial gyroscope values, pitch  29 , roll  31 , and yaw  33  are stored  508 . 
         [0061]    Output from the gyroscope  23  is monitored to detect motion indicating that the user  97  has begun his or her swing  510 . If no motion is detected  512 , the system continues to wait. Once motion is detected  514 , a yaw rate timer is started  516 . Expiration of the yaw rate timer is checked  518 . If the yaw rate timer has not expired  520 , then the yaw value is calculated  522  based on the yaw output  33  of the gyroscope  23 . The yaw value is compared to a range  524 . If the yaw value is not greater than a predetermined yaw range  526 , then processing returns to block  518 . If the yaw value is greater than the predetermined yaw range  528 , then a proper hip turn has been accomplished  530 , the training aid  20  outputs a positive indication in the form of an audio or tactile positive feedback and processing returns  532  to the beginning  113 . 
         [0062]    If the yaw timer expires  534 , then a proper hip turn has not been accomplished  536 . The training aid  20  outputs a negative indication in the form of an audio or tactile negative feedback and processing returns  532  to the beginning  113 . 
         [0063]    Referring to  FIGS. 14 and 15 , use of the training aid  20  is disclosed herein by reference to movements related to a sit-up exercise as an example and for illustrative purposes only. The training aid  20  is not limited to detecting and providing feedback for sit-up exercises movements only. One of ordinary skill in the art will readily recognize other applications for the present invention which are within the scope of this disclosure. 
         [0064]    Referring to  FIG. 14 , a flow chart for selection of an exercise training movement is generally indicated by reference numeral  400 . The exercise training mode is selected  402  and an initial screen is displayed  404 . The user is presented with a number of options to select  406 , including a sit-up exercise mode  408 , a push-ups exercise mode  410 , a bicep curls exercise mode  412 , a lunges exercise mode  414 , a triceps curls exercise mode  416 , and leg lifts exercise mode  418 . Other functions such as play/pause music  420 , show/add music  422  and a settings mode  424  may also be displayed for selection. In the settings mode  424 , options may be entered or selected for the number of sit-ups, the time to complete the selected number of sit-ups, a time interval for each sit-up, a countdown timer, and music to play while exercising, for example. 
         [0065]    Referring to  FIGS. 1 and 15 , if the sit-up mode  408  is selected, the training aid  20  is secured to the middle of the user&#39;s upper arm or chest and the user taps the touch screen  26  to start the sit-ups mode  426 . At this point the accelerometer  22  and countdown timer are started  428 . The output of the accelerometer is filtered  430 . The output of the filter is as follows: 
         [0000]        X =Accel  X *filter constant+ X *(1.0−filter constant)
 
         [0000]        Y =Accel  Y *filter constant+ Y *(1.0−filter constant)
 
         [0000]        Z =Accel  Z *filter constant+ Z *(1.0−filter constant)
 
       Where: 
       [0066]    Accel X, Accel Y and Accel Z are the X, Y, Z values output by the accelerometer  22 . 
         [0067]    Filter const=dt/(dt+RC) 
         [0068]    dt=1.0/50.0 
         [0069]    RC=1/5 
         [0070]    The filter  430  smoothes the values output by the accelerometer  22 . The new X, Y and Z values from the filter  430  are read  432 . If the countdown timer  434  has not expired  436 , processing returns to block  432  to read another set of X, Y and Z values. 
         [0071]    If the countdown timer  434  has expired  438 , the initial X, Y and Z values are checked to determine if the values are stable and indicate a valid starting position  440 . If the values are not stable or are not indicative of a valid sit-up starting position  442 , such as lying on one&#39;s back, then processing returns to the start  426 . If a valid starting position is detected  444 , then the initial values are set  446 . The processor monitors the X, Y and Z values to determine if a sit-up is accomplished  448 . If a sit-up has been accomplished  450 , the repetition count is incremented  452 , and compared to the total repetitions  454 . If the total repetition count has been reached  456 , then the exercise session ends and returns to the start  426 . If the total repetition count has not been reached,  458 , then processing returns for the next sit-up  448 . If a sit-up has not been accomplished  460 , the sit-up encouragement timer is checked  462 . If the sit-up encouragement timer has not expired  464  then processing returns to determine if the sit-up has been completed  448 . If the sit-up timer has expired  466 , then an encouragement sound  468  may be played to encourage the user to keep going or try harder, for example. 
         [0072]    It is to be understood that while certain forms of this invention have been illustrated and described, it is not limited thereto, except in so far as such limitations are included in the following claims and allowable equivalents thereof.