Archive for July, 2012

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Wednesday, July 18th, 2012

Our first full descrip­tion of the Open­Shoe plat­form is now avail­able in the arti­cle: Foot-mounted INS for Every­body — An Open-Source Embed­ded Imple­men­ta­tion which appears in 2012 IEEE/ION Posi­tion and Nav­i­ga­tion Sym­po­sium (PLANS), April 23–26, 2012, Myr­tle Beach, SC, pp140-145.

Required bandwidth

Friday, July 13th, 2012

The ADIS16367 has an ana­logue band­width of some 330[Hz] with the pos­si­bil­ity to turn on low-pass fil­ters. This can be done for the Open­Shoe units with a pro­vided Mat­lab con­trol script. Of cause, higher band­width means more noise and there is no rea­son to have a higher band­width than nec­es­sary. There­fore, I thought I would post some spec­tra of the iner­tial mea­sure­ments taken from nor­mal walk­ing. Below, the spec­tra of the spe­cific force along the x-axis of the IMU is seen:

The fre­quency con­tent along the other axis are sim­i­lar as well as for the angu­lar rate. The con­clu­sion is that most of the power if located below 200[Hz] with the great bulk below 30[Hz]. This means that, for walk­ing motions, low-pass fil­ters can prefer­ably be turned on (or sen­sors with lower band­width can be used). Below is a zip-archive for ref­er­ence with the remain­ing spec­tra in form of Mat­lab figures: