Posts Tagged ‘martial arts’

Punch Acceleration Sensor – Follow Up

April 26, 2010

Couple of questions came up as a result of my post and so after some additional measurements and thoughts, here’s the follow up:

Noise

I have measured the output of ADXL193 accelerometer with the Digital Storage Oscilloscope so here’s how it looks through time as read at the sensor location:

ADXL193 output during AD conversion

AD conversion frequency

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Punch Acceleration Sensor – Part 1

April 4, 2010

After practicing a bit with my makiwara and having a mind of an engineer I wanted to know how hard I am actually hitting. Plus I wanted to see if I can hit as hard from short distance (so called 1 inch punch) as with full swing. So that made me go on a frenzy searching spree to see if there’s anything out there and even what number should I be looking for – is it arm speed or acceleration or board speed? There are actually several studies done on the topic and many good articles written explaining the physics behind it. From what I gathered, a hand hitting a board can cause 200g of acceleration in the matter of 10 milliseconds. This gave me the parameters to look for and also the realization that there’s nothing out there that I could afford to buy. In my searches I stumbled upon SparkFun store and from there the whole world of ICs, microprocessors and electronics. So I have decided to make it myself and couple of months later (yes, things go slow when you don’t know what you’re doing :)) I present you the working product (sorry for the grainy video – needed more light):

I will limit this post to the general system overview and will follow up with post dedicated to hardware and another one for software. All code and designs will be available for free download and you’re welcome to do with it whatever you like.

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DIY Wall Mounted Makiwara

April 2, 2010

Sometime ago I decided to improve my punches and strengthen my knuckles at the same time.  After a quick look online I found out that I need a Makiwara – a padded wooden board mostly used in Karate. Original Makiwara is a large wooden board buried in the ground but i found some room versions of them as well for sale. I could not find exactly what i needed – they were either too small or too large and required floor mounting – so I’ve decided  to build one myself:

DIY Wall Mounted Makiwara

DIY Wall Mounted Makiwara

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