RE: [Paddlewise] Suggestions for kayak velocity measurements

Thanks,

The Bluetooth GPS device might be able to be used (attached to the Talon
paddle) to match in time (stroke for stroke) the angular data from the Talon
paddle's built in sensors and then we could know the kayak's speed via this
Bluetooth GPS devices GPS at the same time the Talon paddle was providing drag
measurements in the direction the kayak was moving with its built in strain
guages.


> Date: Fri, 30 Jul 2010 11:46:38 +0000
> From: rebyl_kayak_at_energysustained.com
> To: marinerkayaks_at_msn.com; paddlewise_at_paddlewise.net
> Subject: Suggestions for kayak velocity measurements
>
> G'Day Matt,
>
>
>
> As promised here are some suggestions for measuring instantaneous kayak
velocity.
>
>
>
> I looked at infrared golf swing meters and ultrasound doppler fetal monitors
and they are certainly cheap enough and accurate enough but would need a fair
bit of modification. Likewise as Craig pointed out, impeller knotmeters and
GPS are not accurate enough. However, as we discussed it should be possible to
measure average velocity and then use it to correct for drift in the 'instant'
velocity derived from the accelerometer.
>
>
>
> I then asked my mate Andrew Eddy, who is very skilled at finding useful
control electronic devices, if there were such a thing as a bluetooth
accelerometer so we could easily link it to a computer and correct for drift
off line. He found someone who sells all the necessary parts as a system.
>
>
>
> Bluetooth GPS devices-logs GPS and acceleration at 1Hz and 10Hz
respectively.
>
> http://www.oceancontrols.com.au/GPS-030.html
>
>
>
> So in one unit you could get fast accelerometer data and slower GPS data to
correct for drift
>
>
>
> They also sell a combined gyro, accelerometer, magnetometer, with three-axis
measures of each, that can connect to a blue tooth modem.
>
> http://www.oceancontrols.com.au/SFG-009.html i
>
>
>
> Bluetooth modem
>
> http://www.oceancontrols.com.au/WIR-010.html
>
>
>
> As you will see from the Youtube video of the 9-axis unit its just what
Andrew and I are after for measuring blade movement in rolls and sweeps and it
might be interesting if you wanted to combine boat pitch roll and yaw with the
paddle signal
>
> http://www.youtube.com/watch?v=WuHRCnpcsDQ
>
>
>
> Andrew and I have ordered the 9 axis unit so I'll be able to try out a
velocity algorithm and tell you whether you need the combined
GPS/accelerometer or whether the 9axis unit and modem will do the job.
>
>
>
> GPS/accel logger $200
>
> 9-axis devices $119
>
> Bluetooth modems $77
>
>
>
> Usual waivers I don't have any financial interest in either Talon or Ocean
Controls.
>
>
>
> Hope this helps, All the best, PeterO
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