Tennis Practice For Hackers


Here’s an interesting WiiMote based project. [Mans] is a tennis fan, though a bit out of practice. With the tennis season coming to a rather climactic end, he got excited and wanted to brush up on his skills. He found the toss part of his serve to be very sloppy. Being a hacker, the first thing he thought was that there must be some way of tracking and graphing his toss so that he could improve it in an intelligent and controlled manner. The WiiMote seemed a perfect fit for this. Only a small modification was necessary, an external button wired to the internal “-” button. This switch is active while he’s holding the ball, and inactive when the ball is released. In this manner, he can track and chart his toss to find out exactly where he needs improvement.  He uses [Johnny Chung Lee]’s code, with a small but unspecified modification to write the accelerometer data to a text file.

As he points out, this could be very usefull for any repetitive movement. Whith accelerometers getting cheaper and cheaper, there’s nothing stopping you from using multiple ones either. Imagine a golf rig to analyze your swing, Maybe a boxing rig that measured your hip twist and arm extension, or possibly a yoyo glove to tell you if your flick needs some help. Great job [Mans].

15 thoughts on “Tennis Practice For Hackers

  1. the serve is the hardest part to do well and the toss is super important. However, it’s hard to know if your toss is right without hitting the ball. This method could be practiced indoors, too.

  2. Not only could this be practiced indoors, you could even do it while watching TV. Like many sports (especially martial arts, golf, baseball, etc.) much of the difference between a good player and a bad player is sheer amount of time practicing to build up muscle memory and perfect your form. This is like a home version of the modern sports medicine techniques. By allowing him to practice anywhere, at any time, it should allow him the chance to improve his game much faster than if he only practiced when he was able to get to a court (or similar sized area). It also should speed things up because he gets exacting feedback separate from any issues caused by weather or his other arm’s swing.

  3. In addition to practicing your tosses, which are quite important, checking your grammar might also be in order. Manor, probably stately as it is, is not how you monitor a technique or manner. The post is quite short and it is not a big deal, but sometimes hackers do know how to read and write in English as well as C and C++. Niggling I know, but still it is important. You can practice both without much sweat.

  4. I have these Wiimotes, and I would not think that having one on your tossing arm would exactly be the best of solutions. There is a weight factor involved, and being as close to the wrist as this setup is, I am certain your toss is being affected. When you attempt to compensate, you will correct your toss according to having monitor equipment, when you remove it, you will be tossing it in a manner that assumes you still have it. If you are interested in sloppy tosses, try doing this. Use and IR led, have the Wiimote on a stand within 10 feet and 45 degrees of the front of the device, then track the device with your software. There have been similar off takes of this, and you are indeed clever to use it in this manner, but something lighter would be of more benefit to you.

  5. This is neat but I’m going to have to go with greycode on this one, im not a tennis player but i am a golfer, and i KNOW that the weight of the Wiimote would change your swing.

  6. mcsquid. i agree that the weight would throw off the swing or toss to a certain degree. i think the issue could be aleviated by stripping the wiimote to the PCB and using a small li-ion battery, or perhaps moving the battery pack to the upper arm or back, where it will have very little effect. actually, if you could just move the accelerometer to the hand and keep the rest of the wiimote on your back, this would be perfect (easy to strap to your hand too).

  7. one of the few disadvantages of this (and any wiimote app really) is the fact that you can’t store information on the wiimote and transmit later. for instance, it would be great if he could do this while waiting for a plane or a taxi with no laptop around. or for those who like the wii fit, being able to run on your own time and just uploading the results later.

  8. “Manor, probably stately as it is, is not how you monitor a technique or manner. The post is quite short and it is not a big deal, but sometimes hackers do know how to read and write in English as well as C and C++. Niggling I know, but still it is important. You can practice both without much sweat.”

    Today, class, we’ve learned that greycode is a prick.

    Seriously, this isn’t Slashdot. As calebcraft has proven, the editors here are willing to correct minor typos. Is it really necessary to flame someone for a simple mistake that spellcheckers can’t catch?

    Consequently, your comment doesn’t even make much sense. Repetitive practice isn’t likely to improve something like the occasional random use of an incorrect homonym. Also, even if you were to play dumb and assume he intended to use manor in the sentence, he would still have been using, perfectly readable, English.

    Really, it’s _not_ important. What’s important, is that you seek help for your neurosis. ;-p

  9. BTW, I wasn’t trying you shouldn’t have said anything at all, I’m just saying that a simple “hey, you made a typo” would have sufficed. If the point of having perfect grammar/spelling is to improve communication, how does it serve your, supposed, goal if you can’t, at least, stay polite?

  10. Although we have been friends for a long time, I didn’t want to embarrase myself with my lack of tennis technique. So I decided to get myself a bit of help before our first session. I “kinda” dissapear of the radar for a couple of weeks. The reason, I was training with an amazing series of oline videos on how to learn to play tennis.

    To my amazement and his, my first class with him wasn’t bad at all. He immediately noticed that I had had “some help” so he asked what I did. I mentioned the videos, he took a peek and was quite impressed.

    I am far from perfection, but I have been doing quite well.

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