Abstract:
Disclosed is an improved method of golf swing analysis. Data gathered from an optical swing pad is processed using various methods. The data is digitally sampled from an array of photo sensors, gathered into multiple frames and sent to a computer processor. Calculations are made from each combination of the frames. Regression analysis is performed on the calculations to determine the clubhead face angle. Using these analytical methods results are often obtained that rival those of more expensive golf swing analyzers such as launch monitors.

Description:
[0001]    This application claims priority to Provisional Application Ser. No. 60/946,846, filed Jun. 28, 2007. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    With the popularity of golf growing from year to year, so has the popularity of various golf simulator games. On the major game counsels these golf simulator games included models of world famous golf courses and thus attempted to place the user at the courses playing in major professional tournaments and often against famous professional golfers. One limitation to the simulation, however, was the use of the game counsel&#39;s hand held data input device. These devices were the same ones used in the other games and very unlike the preferred method of entering a data for a golf simulator game, swinging a golf club. 
         [0003]    There also existed golf simulators that input data by way of a golf club swing. One common version was a device that consisted of two components (1) an “optical swing pad” that collected data and (2) a computer that analyzed the data and predicted the results of the golf swing. 
         [0004]    The optical swing pad consisted of a centrally located golf tee flanked by an array of photo sensors. Typically at least sensor array was located just behind the ball. When a user swings the sensors detect the passage of the club above the sensors. In one common mode, light reflected from the bottom of the golf club is detected. The sensors are monitored by a microcontroller also located in the swing pad. The microcontroller detects which sensors in the array detected reflected light and the time that these sensors detected the light. These data are packaged together and sent to a computer which runs an appropriate mathematical algorithm. Typical algorithms calculate club speed, club face angle and the path of the swing. The results are then displayed to the user. 
         [0005]    While this design has the advantage of being a more realistic than manipulating hand held devices, there were, nevertheless problems with the design. The results were displayed on a generic golf course, not one of the world famous venues featured in counsel games. Also, the quality of the simulation was poor. When a knowledgeable golfer swung a club using one of these devices the golfer has certain expectations of what the real world results should be in terms of ball flight direction and distance. The simulator often produced results that were no match for these expectations. Also some of these devices were very expensive-two to three times that of the counsel games. These simulators were fairly popular and it was generally assumed that these shortcoming were a result of the manner of gathering data. The only means of substantially improving the quality of the simulation would be to use a more elaborate, and expensive, means of gathering data. 
         [0006]    One example is the set of devices known as launch monitors. These devices gather data on ball motion using expensive equipment. Some launch monitors use high speed video equipment, others use Doppler radar. Typically these devices monitor ball flight at a high frequency, for example 100,000 measurements per second. The ball flight data is then used, rather than the golf club motion data, to generate the results of the golf swing. 
         [0007]    Surprisingly, the inventor of the subject matter disclosed herein discovered a problem with the prior art optical swing pad devices. Moreover, the inventor realized the problem could be resolved without recourse to more expensive monitoring equipment or by gathering data on the ball flight rather than the golf club motion. Rather, the problem could be solved by mathematics, specifically a careful use of various statistical algorithms. Using these algorithms, the golf swing simulator described herein is more accurate than a launch monitor in many cases. 
       SUMMARY OF THE INVENTION 
       [0008]    The inventor has created various systems, products and methods, for improving the detecting the speed, face angle and path of a golf club that uses sensors before and after the golf ball. The sensors collect information about the objects that pass over them. From this raw data, the products and methods then perform a regression analysis of every combination of the data sampled. The products and methods look at the leading edge information for the golf club; and, with every sensor change they receive a new ‘frame’ of data. From these data, products and methods use every combination of frames to calculate the face angle, speed and path. The products and methods then discard any values that are out of a predetermined statistical range. This successfully overcame problems with bad data regarding club motion right before and after impact. With this data and data processing, the products and methods are able to calculate the ball flight path and distance. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  illustrates the swing pad, computer and cable connecting the two. 
           [0010]      FIG. 2  illustrates a reflective tape attached to the bottom of a golf club that can be used to aid in detection of passage of the leading edge. 
           [0011]      FIG. 3  illustrates the algorithm used to calculate various aspects of a golf swing such as club speed, face angle, swing path, ball speed and distance traveled. 
           [0012]      FIG. 4  illustrates the algorithm used to calculate the face angle. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    The device gathers using prior art devices as illustrated in  FIGS. 1 and 2 .  FIG. 1  illustrates an optical swing pad  100  which houses: a golf ball tee  130 , a row of sensors (a sensor array) located in the path of the golf club before the golf ball  110 , and, typically, another sensor array behind the golf ball  115 . Located within the swing pad is a microcontroller. When a golf club is swung over the sensors  110 ,  115  the microcontroller can detect which sensors detect the passage of the club over the sensors and the time that the club passes over. 
         [0014]    For some clubs, such as drivers, the shape of the leading edge is irregular and does not generate usable data. In these cases a strip of straight reflective tape can be applied to the club, as shown in  FIG. 3 . The reflective tape  210  is attached to the underside of a golf clubhead  200  such that the leading edge of the tape  215  is parallel to the face of the club. The leading edge of the reflective tape can be accurately detected by the optical swing pad  100  and will generate usable data when sent to the computer  170  by way of the connecting cable  150 . 
         [0015]    In order to improve the results, the inventor of the methods and systems disclosed herein began a trail and error method of analyzing the data gathered by the prior art devices such as diagramed in  FIGS. 1 and 2 . Various sets of golf swings were performed and the results were compared to actual range data and to the state of the art launch monitors. 
         [0016]    Finally, the inventor began combining the data according to statistical principles, a preferred embodiment of which is illustrated in  FIG. 3 . To implement these algorithms the data is first collected. 
         [0017]    One preferred method of data collection is as follows. An optical swing pad is supplied that has two sensor arrays. One array is behind the golf ball, where the club will pass just prior to striking the ball, is called the “strike row.” Another array in front of the ball, where the club will pass as the golfer begins his follow-through, is called the “follow-through row.” The microcontroller is directed to enter “standby” mode when no sensors detect the passage of a golf swing. At some point one or more sensors detect the passage of a golf club. After one or more sensors detect the presence of the golf club, the microcontroller enters and “active” mode and performs the following data collection activities. The sensors detect an increase in light reflected off of the golf club as the leading edge of the golf club begins passing over the sensor. The more light detected by the sensor, the greater the sensor output. Typically, sensor output is a voltage increase but a current increase can also be used. 
         [0018]    While analog sensor data can be gathered (the precise value of the analog output versus time) a preferred method is to gather “sampled digital data” as follows. A threshold level of analog sensor output is defined. Any output below this threshold is considered “OFF” or “0.” When the output exceeds the threshold the sensor is said to “change state” and the value changes from “OFF” to “ON” or from “0” to “1.” When a sensor changes state, the microcontroller records the then current state of every sensor, called a “frame” of data, and adds a “time stamp” which indicates the current time in which the sensors were found in that state. Technically, the microcontroller does not continuously monitor the sensor states. Rather it “samples” the states as discrete time points. A preferred sampling rate is approximately once every 16 microseconds. 
         [0019]    The exact sampling rate can vary. It is believed that smaller sampling rates can be used, even values less than one microsecond. The only limit is the expense. Faster sampling typically requires more expensive microcontrollers, more expensive power sources and sometimes expensive methods to dissipate the extra heat generated. Surprisingly, the inventor has discovered that approximately  16  microseconds is sufficient. 
         [0020]    The microcontroller continues to sample the sensor state and, upon detecting a state change, again records a “frame” of data-the state of every sensor-and adds a time stamp to the frame. This continues either until a certain time limit or a certain limit in frame number is achieved. The entire set of data “frames” is then sent from the optical swing pad  100  to the computer  170 . 
         [0021]    Surprisingly, it is common for only four frames of data to be sufficient to generate a good estimate of the golf swing as judged by comparing the prediction of the computer to the results of a launch monitor or actual data from a driving range. While four frames of data is a preferred embodiment, 2-3 and 5-12 frames are other preferred numbers of frames analyzed. 
         [0022]    After gathering the data, the data is analyzed. A preferred method of analysis is illustrated in  FIG. 3 . After input is detected, the system is activated to calculate a swing. Clubhead speed is calculated from all valid frame combinations. The system then calculates a regressive face angle using strike rows and the follow-through rows. See below. Finally, path angle, ball speed, distance traveled and the amount the ball was “offline” (the amount the golfer missed his target left or right) is calculated 
         [0023]    In general the data are analyzed as follows: In preferred embodiments of the various systems, the sensors are behind the golf ball a specified distance. In order to determine the proper face angle at the exact moment of impact the various systems apply a rotation adjustment that accounts for the natural rotation that occurs in a golf swing. This adjustment is based on the arc created by the club. 
         [0024]    In preferred embodiments of the various systems, the calculation of face angle also has to take into account the shape of the club in question. The inventor adds the concept of club set calibration. This allows a golfer to specify the “offset” of the golf club they are currently swinging. The offset of a golf club (if any) introduces an artifact, making a golf club which is nearing impact appear more open than is actually the case. By adjusting for offset the inventors were are able to get very accurate actual face angle calculations at the point of impact. 
         [0025]    All of the above was done for irons without modifications. Another preferred embodiment is modified with Driver/Wood support. These modifications can include affixing a reflective strip to the leading edge of the club as explained above. The system can use the leading edge data as described above to calculate speed, face, angle and path. In a preferred embodiment, the inventor has modified the reflective strip to have varying widths and an irregular trailing edges to demonstrate that only leading edge data is used. 
         [0026]    The systems use unique algorithms for calculating the speed of the club head. Because the ball may trigger the sensors before the club, the speed calculation needs to be able to filter out ball detection. The systems use a “speed delta plus (+) ‘x’ frames” algorithm that yields improved quality data. When calculating the speed, the systems measure the time delta between each pair of frames. These products and methods then determine the largest delta. Then, depending on the ball type (for example, foam or real), the systems look x frames beyond the delta. (Where x is typically between 2 and 6.) This variation can significantly increase accuracy of speed calculations. 
         [0027]    Another preferred embodiment includes, as a piece of logic, the “club orientation method.” The club orientation method is called for each face angle calculation. The systems analyze all possible combinations of data using regressive analysis of all the available frames. If the results are not conclusive then the systems assume the most statistically probable orientation (open) prior to impact. 
         [0028]    A preferred embodiment of face angle calculation is illustrated in  FIG. 4 . All possible combinations of frames are combined as illustrated, face angles are calculated, those angles that are out of range are discarded until an “end face angle” results. 
         [0029]    Included as an appendix is source code for a preferred embodiment of the invention and is not meant to limit the scope of the invention in any way. This embodiment includes the above implementations which have been completed as of the filing date.