Patent Publication Number: US-9409074-B2

Title: Recommending sports instructional content based on motion sensor data

Description:
BACKGROUND 
     This invention relates generally to digital content processing and particularly to sports video content ranking and recommendation based on analysis of captured sports motions. 
     Motion detection and recognition of a moving object, such as a golf swing, are widely used to enhance athletes&#39; performance. The techniques for path and stance recognition for spatial accelerated motion can be used in combination with human body actions for detection of human body actions in the field of sports. Taking golf as an example, golf is a sport that often requires good control of motions of a golf club, and an accurate analysis of the golf swing motions detected by a motion sensor can enhance golf players&#39; performances. One way to enhance a player&#39;s sports performance is to analyze the motion data captured during game play and then to study highly relevant instructional content, e.g., videos, regarding various aspects of the player&#39;s performance. 
     The development of digital media content sharing and Internet social networking has enabled sports players to post, view and share instructional videos illustrating various aspects of a sport. However, it may be difficult and/or time consuming for sports players to find and select appropriate sports instructional content among a large amount of available sports instructional content of varying quality and relevance. Existing solutions of sports instructional content selection and recommendation related to sport performance enhancement face challenges to provide highly relevant sports instructional content tailored according to individual players&#39; needs with enhanced user experiences. 
     SUMMARY 
     Embodiments of the invention provide a solution to enhance sports performance of users of a recommendation service. The recommendation service ranks sports instructional content based on motion data associated sports playing and provides highly relevant sports instructional content based the ranking to the users. 
     A computer-implemented method for recommending a sports video content sample related to a user&#39;s sports motion is disclosed. Embodiments of the method comprise generating voting scores for sports video content samples, golf video clips, according to a voting method, and selecting from among the sports content samples according to the voting scores for the sports video content samples. The voting method is based on in part on motion data for the user&#39;s sports motion and the motion data is captured by a motion data device. The sports video content samples, e.g., golf videos, can be classified into multiple classes, e.g., golf swing power related videos, and each class is related to a different aspect of the sports motion. 
     Embodiments of the method further comprise generating multiple voting scores for the sports video content samples according to multiple voting methods, generating aggregated voting scores for the sports video content samples based on combining the voting scores generated for each voting method and selecting from among the sports content samples according to the aggregated voting scores for the sports video content samples. 
     Another aspect provides a non-transitory computer-readable storage medium storing executable computer program instructions for recommending a sports video content sample related to a user&#39;s sports motion as described above. The features and advantages described in the specification are not all inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the disclosed subject matter 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a computing environment for recommending sports instructional content according to one embodiment. 
         FIG. 2  is a block diagram illustrating an example of a computer for acting as a client device and/or recommendation server according to one embodiment. 
         FIG. 3  is a block diagram of a sports instructional content recommendation engine according to one embodiment. 
         FIG. 4  is an exemplary flowchart illustrating a process of ranking sports instructional content according to one embodiment. 
         FIG. 5  illustrates steps of ranking and selecting sports instructional content according to one embodiment. 
         FIG. 6  shows examples of golf instructional videos for improving various aspects of golf playing performance of a player. 
         FIG. 7  shows examples of recommended videos for improving golf playing performance in terms of handling a golf club. 
         FIG. 8  shows an example of presenting golf club path aspect of a golf swing by a user of the recommendation service. 
         FIG. 9  shows an example of presenting golf club plane aspect of the golf swing illustrated in  FIG. 8 . 
         FIG. 10  shows an example of various motion parameters related to a golf swing by a user of the recommendation service. 
         FIG. 11  shows an example of presenting impact of a golf swing on a golf ball and a trend of club speed during the whole process of a golf swing. 
         FIG. 12  illustrates a graphical user interface for users to customize their golf swinging goals. 
         FIG. 13A  shows a graphical user interface for presenting three recommended videos for improving performance on club speed. 
         FIG. 13B  shows a graphical user interface for presenting a user&#39;s performance on golf club speed. 
     
    
    
     The figures depict various embodiments of the present invention for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the invention described herein. 
     DETAILED DESCRIPTION 
     System Overview 
     A solution is provided to enhance sports performance of users of a recommendation service. The recommendation service ranks sports instructional content based on motion data associated with sports playing and provides to the users highly relevant sports instructional content based on the ranking  FIG. 1  is a block diagram of a computing environment  100  for recommending sports instructional content according to one embodiment. The embodiment illustrated in  FIG. 1  includes a client device  110 , a content provider  120 , a motion data device  130  and a recommendation service  140  connected to each other by a network  150 . Only one of each entity is shown in  FIG. 1  in order to simplify and clarify the description. Embodiments of the computing environment  100  can have many client devices  110 , content providers  120 , motion data devices  130  and recommendation services  140  connected to the network  150 . Likewise, the functions performed by the various entities of  FIG. 1  may differ in different embodiments. 
     A client device  110  is an electronic device used by a user to perform functions such as consuming digital content, executing software applications, browsing websites hosted by web servers on the network  150 , downloading files and the like. For example, the client device  110  may be a media streaming device, a smart phone, or a tablet, notebook, or desktop computer. The client device  110  includes and/or interfaces with a display device on which the user may view videos and other content. In addition, the client device  110  provides a user interface (UI), such as physical and/or on-screen buttons, with which the user may interact with the client device  110  to perform functions such as viewing, selecting, and consuming digital content such as sports instructional videos. 
     The content provider(s)  120  provides digital content of various sports to the recommendation service  140 . In one embodiment, the digital content provided by the content provider  120  includes videos, digital images and text description that are designed to guide users on how to improve their sports performance in various sports, e.g., golf, baseball and tennis. Examples of golf instructional videos include videos of professional golf players playing golf, e.g., Steve Sticker, provided by Golf Channel. In one embodiment, the content provider  120  is professional broadcasters of sports events. In another embodiment, the content provider  120  is anyone who has access to a digital camera and a connection to the Internet, such as viewers of sports events. The digital content stored in a video database of the recommendation service  140  may be classified into different types, such as videos on speed, tempo, positions of sport instruments, and subtypes, such as golf videos on club speed and golf videos on hand speed. 
     In this disclosure, “digital content” or “digital media content” generally refers to any machine-readable and machine-storable work. Digital content can include, for example, video, audio or a combination of video and audio. Alternatively, digital content may be a still image, such as a JPEG or GIF file or a text file. For purposes of simplicity and the description of one embodiment, the digital content will be referred to as a “video,” “video files,” or “video items,” but no limitation on the type of digital content that can be analyzed are intended by this terminology (except that they must include video). Thus, the operations described herein for analyzing and ranking video content can be applied to any type of digital content, including videos and other suitable types of digital content such as audio files (e.g. music, podcasts, audio books, and the like), documents, websites, images, multimedia presentations, and others. 
     The motion data device  130  captures motion data of a player during sports play. In one embodiment, the motion data device  130  is a motion sensor inserted inside a sports instrument or attached to the sport instrument, which is configured to detect motions associated with movements using the sports instrument. Each detected motion has multiple associated motion parameters. Taking a golf swing as an example, the motion parameters associated with the golf swing may include club speed, club plane, hand plane, tempo, backswing, hand speed and hips. Examples of the motion data device  130  include microelectronicmechanical systems (MEMS) sensors, electromyography (EMG) sensors and digital cameras. Examples of the embodiments of these motion sensors and motion detection and recognition systems based on motion parameters include those described in U.S. Patent Publication No. 2012/0277890 and U.S. Pat. No. 8,725,452, each of which is incorporated by reference herein in its entirety. 
     The network  150  enables communications among the client device  110 , the content provider  120 , the motion data device  130  and the recommendation service  140 . In one embodiment, the network  150  comprises the Internet and uses standard communications technologies and/or protocols. In another embodiment, the entities can use custom and/or dedicated data communications technologies. 
     The recommendation service  140  receives sports video content provided by the content provider  120  and stores the sports video content in a video database. The recommendation service  140  also receives motion data captured by the motion data device  130  during sports play and stores the motion data in a motion database. The recommendation service  140  analyzes the sports video content and the motion data and recommends selected sports video content as sports instructional content recommendations to users based on the analysis. In one embodiment, the recommendation service  140  includes a video database  142  for storing sports video content provided by the content provider  120 , a motion database  144  for storing motion data captured by the motion data device  130  and a recommendation engine  300  for ranking, selecting and providing sports instructional video content recommendations to users of the client device  110 . The recommendation engine  300  is further described with reference to  FIG. 3 ,  FIG. 4  and  FIG. 5  below. 
     Computing System Architecture 
     The entities shown in  FIG. 1  are implemented using one or more computers.  FIG. 2  is a high-level block diagram of a computer  200  for acting as the content provider  120 , the recommendation service  140 , the motion data device  130  and/or a client device  110  according to one embodiment. Illustrated are at least one processor  202  coupled to a chipset  204 . Also coupled to the chipset  204  are a memory  206 , a storage device  208 , a keyboard  210 , a graphics adapter  212 , a pointing device  214 , and a network adapter  216 . A display  218  is coupled to the graphics adapter  212 . In one embodiment, the functionality of the chipset  204  is provided by a memory controller hub  220  and an I/O controller hub  222 . In another embodiment, the memory  206  is coupled directly to the processor  202  instead of the chipset  204 . 
     The storage device  208  is any non-transitory computer-readable storage medium, such as a hard drive, compact disk read-only memory (CD-ROM), DVD, or a solid-state memory device. The memory  206  holds instructions and data used by the processor  202 . The pointing device  214  may be a mouse, track ball, or other type of pointing device, and is used in combination with the keyboard  210  to input data into the computer system  200 . The graphics adapter  212  displays images and other information on the display  218 . The network adapter  216  couples the computer system  200  to the network  150 . 
     As is known in the art, a computer  200  can have different and/or other components than those shown in  FIG. 2 . In addition, the computer  200  can lack certain illustrated components. For example, the computers acting as the recommendation service  140  can be formed of multiple blade servers linked together into one or more distributed systems and lack components such as keyboards and displays. Moreover, the storage device  208  can be local and/or remote from the computer  200  (such as embodied within a storage area network (SAN)). 
     As is known in the art, the computer  200  is adapted to execute computer program modules for providing functionality described herein. As used herein, the term “module” refers to computer program logic utilized to provide the specified functionality. Thus, a module can be implemented in hardware, firmware, and/or software. In one embodiment, program modules are stored on the storage device  208 , loaded into the memory  206 , and executed by the processor  202 . 
     Sports Instructional Content Ranking and Recommendation 
       FIG. 3  is a block diagram of a sports instructional content recommendation engine  300  according to one embodiment. The recommendation engine  300  analyzes the sports video content, e.g., sports video clips from the content providers  120  stored in the video database  142 , and the motion data stored in the motion database  144  and recommends sports instructional video content to users of the recommendation service  140 . In one embodiment, the recommendation engine  300  ranks the video clips in the video database  142  based on the user&#39;s motion data in the motion database  144  through one or more voting processes. In each voting process, the recommendation engine  300  generates a voting score for a video clip of the sports video clips. A voting score indicates the sports performance of the player in the video clip with respect to the measurement by the corresponding voting method, some of which also take into account the user&#39;s motion data. The recommendation engine  300  selects a number of sports video clips as recommendations to the users based on the corresponding voting scores of the sports video clips. 
     In one approach, let parameter μ be the quantity of sports motions captured by the motion data device  130  and parameter ν be one motion sample out of μ. Let parameter N total  be different types of sports instructional content provided by the content provider  120 . Parameter n stands for one type of sports instructional content out of N total , and parameter n i  is one content sample of the type of sports instructional content represented by parameter n. For each content sample n i , the recommendation engine  300  generates a voting score V j (n i ) using a voting process of multiple voting processes j (jε[0, m]), and ranks the content sample n i , among all the content samples of the same type based on the voting scores of the content sample n i . 
     Taking golf as an example, parameter μ represents a number of golf related motions, such as 1000 golf swings captured by a motion data device  130  (e.g., a motion sensor attached to a player&#39;s golf club) and parameter v represents one of the 1000 golf swings. Parameter N total  represents the number of golf videos received from the content providers  120 , e.g., Golf Channel and ESPN, and the content of the golf videos can be classified into different types, such as swing power related content, swing accuracy related content and swing rhythm related content. Each video can be classified as more than one type. Parameter n represents a number of the golf videos of one classification, such as 10,000 golf videos related to swing power, and parameter n i  is a video clip of the 10,000 golf videos related to swing power. The recommendation engine  300  generates a voting score for each video clip of the 10,000 golf videos related to swing power for each voting process and ranks the 10,000 golf videos based on the voting scores of the video clips. 
     To further illustrate the voting processes by the recommendation engine  300  with above defined parameters,  FIG. 4  is an exemplary flowchart illustrating a process of ranking a sports video content sample by the recommendation engine  300  according to one embodiment. Initially, the recommendation engine  300  receives  402  a content sample n i  and generates  404  a voting score V 0 (n i ) using a voting method measuring how much time spent by a user of the recommendation service  140  on the content sample n i , e.g., number of times that the user watched the content sample n i . The recommendation engine  300  may generate 406 another voting score V 1 (n) based on a measurement of the differences between the content sample n i  and a mean value of content samples of the same type. 
     At step  408 , the recommendation engine  300  generates a voting score V j (n) using a voting method evaluating the consistency of content sample with respect to other content samples of the same type. At step  410 , the recommendation engine generates a voting score V j+1 (n) based on a voting method rating the content sample n i  with respect to user input on the content sample. 
     The recommendation engine  300  may generate additional voting scores using additional and/or different voting methods. The voting methods can be independent from each other and more than one voting method can be selected by a user of the recommendation service  140  according to different applications, e.g., golf, baseball or tennis. Upon receiving the selection of voting method(s), the recommendation engine  300  generates  412  an aggregated voting score for the content sample n i . In one embodiment, the recommendation engine  300  adds the voting score for each selected voting process to generate the aggregated voting score. Based on the aggregated voting scores for each content sample n i , the recommendation engine  300  ranks the content samples and presents as recommendations to the users one or more content samples selected based on the ranking. 
     Referring back to  FIG. 3 , the recommendation engine  300  illustrated in  FIG. 3  includes a frequency module  310 , a deviation module  320 , a consistency module  330 , a content rating module  340 , a refinement module  350  and a selection module  360 . Other embodiments of the recommendation engine  300  can have different and/or additional computer modules. Likewise, the functions performed by the various entities of  FIG. 3  may differ in different embodiments. 
     The frequency module  310  of the recommendation engine  300  generates a voting score for a content sample n i  based on how much time spent by a user of the recommendation service  140  on the content sample. In one embodiment, the time that a user spends on viewing/studying video clips related to a certain type of sport content n is defined as T 0 (n). For each type of the sports content, the frequency module  310  computes a score V 0 (n) inside a score range [0, θ 0 ] as follows using Equation 1, where θ 0  is a configurable parameter for different applications of the recommendation service  140 . 
                       V   0     ⁡     (   n   )       =       θ   0     ⁢              T   0     ⁡     (   n   )         max   ⁡     (       T   0     ⁡     (   n   )       )              ⁢           ⁢     (     n   ∈     N   total       )               (   1   )               
Initially, each content sample n i  out of the total content samples n of a particular type of sports content gets the same initial score V 0 (n), i.e., V 0 (n i )=V 0 (n), where the initial score V 0 (n) is configurable and an example score of V 0 (n) for golf backswing type videos is 70.
 
     The deviation module  320  of the recommendation engine  300  generates a voting score for a content sample n i  based on a shifted standard deviation of the content sample with respect to all content samples of the same type of content n. In one embodiment, the deviation module  320  linearly shifts all content samples n such that the voting scores of the content samples have positive values. For each type of content samples n, the deviation module  320  selects a universal or a customized standard value S(n) and the average value of total sports motions μ in each type of content n as Avg(n) and calculates the deviation as follows using Equation 2. 
     
       
         
           
             
               
                 
                   
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     In one embodiment, the deviation module  320  calculates the deviation using a customized standard value S(n) based on user input. A customized standard value related to a type of sport content enables a user of the recommendation service  140  to customize his/her own goal as compared with a default value set by the recommendation engine  300 . Taking golf club speed as an example, the default value set by the recommendation engine  300  is 90 mph (miles per hour), while a user of the recommendation service  140  may set his/her own goal for club speed as 95 mph or 85 mph. 
       FIG. 12  shows a graphical user interface (GUI)  1210  for users to customize their golf swinging goals on various aspects of golf swing, including tempo, backswing position and club plane comparison. The GUI  1210  includes an indication of customization  1220  and a slider for customizing each aspect of golf swing. A user may customize the values for each aspect of golf swing by sliding the corresponding slider. The GUI  1210  presents the customization by highlighting the selected values for each customization. 
     Returning back to the deviation module  320 , the deviation module  320  generates a voting score for each type of content samples V 1 (n) inside a score range [0, θ 1 ] as follows using Equation 3, where θ 1  is a configurable parameter for different applications of the recommendation service  140 . 
                       V   1     ⁡     (   n   )       =       θ   1     ⁢                 Δ   ⁡     (   n   )              max   ⁡     (          Δ   ⁡     (   n   )            )              ⁢           ⁢     (     n   ∈     N   total       )               (   3   )               
In one embodiment, for each content sample n i , the deviation module  320  manually tags n i  with a relative factor C(n i ), where C(n i ) is defined as C(n i )ε[0,1]. The deviation module  320  adjusts the voting score for n i  as follows using Equation 4.
 
 V   1 ( n   i )= C ( n   i ) V   1 ( n )  (4)
 
     In one embodiment, the parameter C(n i ) is a 0%-100% factor that indicate whether a content sample n i  is suitable if the Δ(n) in a certain range. For example, in the content samples related to golf backswing position, some content samples are highly relevant on how to improve a user current performance related to golf backswing position by reducing the backswing position from 300 degrees to 270 degrees; some other content samples are highly relevant on how to increase the user&#39;s backswing position from 240 degrees to 270 degrees. The value of 270-degree is an example standard value represented by parameter S(n) used in Equation 2 above. 
     The consistency module  330  measures consistency of a content sample relative to other content samples of the same type. For example, the consistency module  330  checks how stable a particular golf swing is with respect to other 100 golf swings. In one embodiment, the consistency module  330  measures the consistency of a content sample by calculating standard variance of total sports motions μ among each type of content samples n as v(n). The consistency module  330  calculates a voting score for each type of content samples as V 2 (n) inside a score range [0, θ 2 ] as follows using Equation 5, where θ 2  is a configurable parameter for different applications of the recommendation service  140 . 
     
       
         
           
             
               
                 
                   
                     
                       
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     The content rating module  340  generates a voting score V 3 (n i ) for a content sample n i  based on an average rated score R avg (n i ) and a total rated score R t (n i ) based on user input. In one embodiment, a user of the recommendation service  140  is presented with a GUI that allows the user to rate content of a sports video, e.g., assigning a number of stars to the content. The content rating module  340  calculates the voting score V 3 (n i ) as follows using Equation 6, where θ 3   avg  and θ 3   t  are configurable parameters for different applications of the recommendation service  140 . 
     
       
         
           
             
               
                 
                   
                     
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     Sometimes, the users of the recommendation service  140  may want to see different sports instructional content after each performance or session of a play, even if the motions of the multiple sessions are quite similar with each other. To enhance user experience in this situation, the refinement module  350  of the recommendation engine  300  sorts the content samples of the same type and reduces the voting scores of duplicated content samples. In one embodiment, a content queue ε lists the content samples to be sorted, and the refinement module  350  sorts the content samples of the content queue ε in terms of time, e.g., from the latest to the oldest. Given that the content queue ε has a length of δ, the refinement module  350  traverses each element of ε and generates a voting score V 4 (n i ) as follows using Equation 7, where θ 4  is a configurable parameter for different applications of the recommendation service  140 . Initially, all V 4 (n i ) has an initial value of 0. 
     
       
         
           
             
               
                 
                   
                     
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     The selection module  360  generates  412  an aggregated voting score for the content sample n i  upon receiving a selection of voting method(s). In one embodiment, the selection module  360  adds the voting score of the content sample n i  for each selected voting process to generate the aggregated voting score as follows using Equation 8, where m represents a total number of selected voting methods.
 
 P ( n   i )=Σ j=0   m−1   V   j ( n   i )  (8)
 
The selection module  360  generates the aggregated voting score for each content sample n i  of the content samples of the same type n and ranks the content samples based on their corresponding aggregated voting scores. In one embodiment, the selection module  360  ranks the content samples from the highest voting score to the lowest voting score and selects one or more content samples as recommendations to the users of the recommendation service  140  based on the ranking. The recommendation engine  300  presents the recommendations periodically to the users, e.g., every week or every month.
 
     In each voting process described above, the recommendation engine  300  generates a voting score for a content sample (e.g., a sports video clip) using a configurable scaling factor θ, e.g., θ 0 , θ 1 , θ 2 , θ 3   avg , θ 3   t  and θ 4 . The scaling factor θ is configurable for different applications of the recommendation service  140 , e.g., golf, baseball or tennis. In one embodiment, a scaling factor represents relative importance of the corresponding voting method in the overall voting and ranking process by the recommendation engine  300 . Taking golf swing as an example, the example values of these scaling factors are θ 0 =100, θ 1=50 , θ 2 =50, θ 3   avg =100, θ 3   t =100 and θ 4 =50. 
       FIG. 5  illustrates steps of ranking and selecting sports instruction content by the recommendation engine  300  according to one embodiment. Initially, the recommendation engine  300  receives  510  a content sample of a type of sport, e.g., a video clip on golf backswing. The recommendation engine  300  initializes  520  the voting score of the content sample using frequency data of the content sample, e.g., how many times a user has reviewed the content sample. The recommendation engine  300  may evaluate the content sample based on how different the content sample from the average of other content samples of the same type of sports by generating  530  a voting score based on the deviation of the content sample. 
     The recommendation engine  300  may also consider the consistency of the content sample with respect to all types of sports video content received by the recommendation service  140 . For each type of content samples, the recommendation engine  300  generates  540  a voting score based on the standard variance of the all types of sports video content. To further engage the users of the recommendation service  140 , the recommendation engine  300  may evaluate the content sample based on input of an individual user or all users who rate the content sample. The recommendation engine  300  generates  550  a voting score for the content sample based on the user input. 
     To enable users to view different sports instructional content after each performance or session of a play without presenting duplicate content samples to the users, the recommendation engine  300  queues content samples that are to be presented to the users and sorts the content sample queues to identify  560  duplicate content samples based on augmented voting scores of the content samples. Responsive to one or more voting methods selected by a user for a type of sport, e.g., golf, the recommendation engine  300  generates an aggregated voting score for the content sample and ranks  570  the content samples of the same type of sports instructional content based on their corresponding aggregated voting scores. The recommendation engine  300  selects  580  one or more content samples based on the ranking and presents the selected content samples as recommendations to the users of the recommendation service  140 . 
     Application of Sports Instructional Content Recommendation 
     The solution for recommending highly relevant sports instructional content relevant to improve sports performance of users of the recommendation service  140  described above can be applied to various types of sports. The following figures illustrate an application of the solution to playing golf. The solution described above is readily applicable to other types of sports, such as baseball and tennis. 
       FIG. 6  shows examples of golf instructional videos for improving various aspects of golf playing performance of a user. The example in  FIG. 6  shows that the recommendation service  140  provides instructional content in forms of videos on various aspects of playing golf. The golf videos can be provided by golf content providers, such as Golf Channel and ESPN. The types or classifications of the golf videos include backswing  610 , club plane  620  and club speed  630 . The backswing videos are related to a measurement of degrees of the angle of a golf club shaft between address and top of backswing. The measurement of the degrees is based on the change in the angle at the top of the backswing. At the address of the backswing, the club is at zero degree. The club plane videos are related to a measurement of the relationship between a club head of a downswing and the club head of a backswing, the corresponding distance and location of the club head at different swing positions. The club speed videos are related to a measurement of how fast a player&#39;s club head is travelling at the point the club head touches a golf ball. The recommendation service  140  can provide additional and/or different videos on other aspects of playing golf. 
     Under each classification of golf videos shown in  FIG. 6 , the recommendation service  140  further classifies the videos into subcategories. Taking backswing  610  as an example, the recommendation service  140  provides videos on subcategories of backswing, including backswings  612  illustrated by instructors selected by the operators of the recommendation service (i.e., “Zepp Backswing”), the backswings  614  illustrated by professional golfer Steve Stricker (i.e., “Stricker Drill”) and the backswings  616  focusing on coordination of a player&#39;s arm and shoulder (i.e., “Shaft Shoulder”). 
       FIG. 7  shows examples of recommended videos  720  for improving golf playing performance in terms of handling a golf club  710 . The example in  FIG. 7  shows three recommended videos on golf club handling for a user based on the user&#39;s golf club handling statistics  730 . In one embodiment, the user&#39;s golf club handling statistics are generated from motion parameters associated with club swings performed by the user and the club swings were captured by a motion sensor attached to the golf club used by the user. The motion parameters associated with a detected motion are collected through the motion sensor and analyzed by the recommendation service  140 . Taking a golf swing as an example, the motion parameters associated with the golf swing may include, club speed, club plane, hand plane, tempo, backswing, hand speed and hips. Motion parameters related to hips measures the degrees of rotation of hips on backswing and impact of the rotation on backswing. The hand plane parameters measure the relationship between a player&#39;s hand plane of a downswing to a backswing, the relative distance and location of the downswing and the backswing. In the example shown in  FIG. 7 , the motion parameters related to the golf club handling include tempo  732 , backswing position  734 , club plane comparison and hand plane comparison. For each motion parameter shown, the recommendation service  140  also shows average performance data, target performance data (i.e., “GOAL”) set by the user and a performance chart. 
       FIG. 8  shows an example of presenting golf club path aspect of a golf swing by a user of the recommendation service  140 . Path and stance recognition for a spatial accelerated motion refers to detecting position and intersection angles of a moving object (e.g., a golf club swung by a player) at each time in the movement and obtaining real-time velocity of the mobbing object. In the example shown in  FIG. 8 , the user performance on g golf swing captured by a motion sensor has a performance score  810  (e.g.,  88 ). The performance score on the golf swing is calculated in association with the motion parameters associated with the golf swing, e.g., club speed, club plane, hand plane, tempo, backswing, hand speed and hips. In one embodiment, the performance score on the golf swing is a weighted average score of the measurement of the associated motion parameters. The club path of the golf swing is illustrated by the curved lines  820  drawn based on the analysis of the motion parameters related to the club path  830  of the golf swing. The user performance video has a rating of 1 based on user input on the content of the video, where the rating is represented by the star  840 . 
     For a golf swing, the recommendation service  140  presents the users various aspects of the swing.  FIG. 9  shows an example of presenting golf club plane aspect of the golf swing illustrated in  FIG. 8 . A club plane measures the relationship between a club head of a downswing and the club head of a backswing, the corresponding distance and location of the club head at different swing positions. The example in  FIG. 9  shows the club plane of the golf swing represented by the curved surfaces  910  drawn based on the analysis of the motion parameters related to the club plane  820  of the golf swing. 
       FIG. 10  shows an example of various motion parameters related to a golf swing by a user of the recommendation service. A golf swing analyzed has seven associated motion parameters, including club speed  1020 , club plane  1030 , hand plane  1040 , tempo  1050 , backswing  1060 , hand speed  1070  and hips  1080 . These seven motion parameters contribute to the calculation of performance scores of various aspects of golf swing. Taking club speed  1020  as an example and assuming that the performance goal of club speed  1020  parameter is 95 mph, and a weighting factor is 1/7, the contribution of club speed  1020  parameter to the calculation of a user&#39;s performance score on a golf swing (e.g., the golf swing shown in  FIG. 8  and  FIG. 9 ) is 13.233, which is ( 88/95*100* 1/7). For each motion parameter, the player&#39;s performance related to that motion parameter is recorded and presented to the player. 
       FIG. 11  shows an example of presenting impact of a golf swing on a golf ball in terms of club speed and a trend of club speed during the whole process of a golf swing. The presentation illustrated in  FIG. 11  shows a performance score  1110  of a player on club speed (e.g., 88 mph) and the player&#39;s goal  1140  (e.g., 94 mph). The presentation allows the player to show the impact  1120  in terms of club speed of the club head on a golf ball at various observed time slots. The presentation also shows the player the trend of club speed during the whole process of a golf swing in a form of chart  1130 . 
       FIG. 12  illustrates a GUI for users of the recommendation service  140  to customize their golf swinging goals as described above.  FIG. 13A  shows a GUI for presenting three recommended videos for improving performance on club speed. The recommended videos  1310  are presented to the player weekly and the recommended videos can be delivered to a user via electronic mails (emails), to a user&#39;s electronic device that executing an application of the recommendation service or shown on a webpage of the application of the recommendation service on a website hosted by the recommendation service  140 . 
       FIG. 13B  shows a GUI for presenting a user&#39;s performance on golf club speed  1320 . Given the current performance data regarding golf club speed, i.e., 70 mph, of the user and his/her goal to achieve (i.e., 85 mph), the recommendation service  140  ranks the videos on club speed based on their aggregated voting scores, and selects a number of highly relevant videos for the user based on the ranking. The recommended videos are periodically presented to the user, e.g., by weekly as shown in  FIG. 13A . 
     General 
     The foregoing description of the embodiments of the invention has been presented for the purpose of illustration; it is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Persons skilled in the relevant art can appreciate that many modifications and variations are possible in light of the above disclosure. 
     Some portions of this description describe the embodiments of the invention in terms of algorithms and symbolic representations of operations on information. These algorithmic descriptions and representations are commonly used by those skilled in the data processing arts to convey the substance of their work effectively to others skilled in the art. These operations, while described functionally, computationally, or logically, are understood to be implemented by computer programs or equivalent electrical circuits, microcode, or the like. Furthermore, it has also proven convenient at times, to refer to these arrangements of operations as modules, without loss of generality. The described operations and their associated modules may be embodied in software, firmware, hardware, or any combinations thereof. 
     Any of the steps, operations, or processes described herein may be performed or implemented with one or more hardware or software modules, alone or in combination with other devices. In one embodiment, a software module is implemented with a computer program product comprising a computer-readable medium containing computer program code, which can be executed by a computer processor for performing any or all of the steps, operations, or processes described. 
     Embodiments of the invention may also relate to an apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes, and/or it may comprise a general-purpose computing device selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a non-transitory, tangible computer readable storage medium, or any type of media suitable for storing electronic instructions, which may be coupled to a computer system bus. Furthermore, any computing systems referred to in the specification may include a single processor or may be architectures employing multiple processor designs for increased computing capability. 
     Embodiments of the invention may also relate to a product that is produced by a computing process described herein. Such a product may comprise information resulting from a computing process, where the information is stored on a non-transitory, tangible computer readable storage medium and may include any embodiment of a computer program product or other data combination described herein. 
     Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based hereon. Accordingly, the disclosure of the embodiments of the invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.