Matt and Craig, How about doppler ultrasound for the velocity? Of course its widely used but would it be accurate enough? Some web references below relevant to the technology and my comments about combining gyros and accelerometers. Reference 3 describes the potential use of multiple (4) IMU magnetometers to measure velocity and position. Might be worth asking if Talon are considering a similar approach. http://invensense.com/kr/mems/gyro/documents/articles/motion_sensing_accel_human.pdf http://cvlab.epfl.ch/publications/publications/2006/DejnabadiJCFA06.pdf http://cas.ensmp.fr/~petit/papers/cdc07/DV.pdf All the best, PeterO *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Peter wrote: - How about doppler ultrasound for the velocity? Of course its widely used but would it be accurate enough? Some web references below relevant to the technology and my comments about combining gyros and accelerometers. Reference 3 describes the potential use of multiple (4) IMU magnetometers to measure velocity and position. Might be worth asking if Talon are considering a similar approach. http://invensense.com/kr/mems/gyro/documents/articles/motion_sensing_accel_h uman.pdf http://cvlab.epfl.ch/publications/publications/2006/DejnabadiJCFA06.pdf http://cas.ensmp.fr/~petit/papers/cdc07/DV.pdf G'Day, Matt, I should have asked earlier what accuracy and time resolution are you seeking and over what distance. MEMS (microelectromechanical) accelerometers are improving rapidly; it might now be feasible to get one with a good enough S/N and low enough drift that attaching it to the kayak and carrying out an integration and calibration gives you its velocity over reasonable distances. It might also be possible to carry out a timed reset and recalibration at intervals. Possibly cheaper than buying a doppler ultrasound although if you could find a discarded fishing sonar its probably not too hard to extract the piezo element and rig up a doppler and frequency counter. They run at about 200kHz so the resolution limit is going to be two or three cm per sec velocity error. You might also be able to derive an average velocity from the paddle accelerometers although the paddle movement means it wouldn't average fast enough for multiple values during a paddle stroke. The sales rep at Talon told me they don't derive linear velocity from the accelerometers but seemed interested in the possibility. BTW I've mentioned Paddlewise to the engineers at Talon, hopefully they may log on. All the best, PeterO *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Carey wrote .........I was stumbling around in the Android Marketplace looking for cool stuff for my phone (and I use that term "phone" loosely) and I ran across an app for rowing that displays and records the boat acceleration and also infers stroke rate, and some other things by using the "phone's" integrated GPS and three axis accelerometer. It's pretty good. Both the app and my device. .......http://nargila.org/trac/robostroke/wiki ....... It of course does not integrate paddle dynamics, ................................. G'Day Carey, That is very clever though I know very little about using that kind of phone. I'm guessing it is something like an ipod and has one of those screens that you can turn round and the image turns with you? Does it have Blue tooth? If so can you download the data through the bluetooth port onto a computer? Then it would be relatively simple to time link the data to a Talon paddle so long as they were willing to fit a blue tooth modem to their data stream. Alternatively one could start the data recording on both paddle and phone and then provide a synchronising single by tapping the paddle on the kayak before and after the test run. crude but effective synchronising. Any further details would be greatly appreciated? All the best, PeterO *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Peter, I've uploaded some of the data I collected today to Box.net and sent you an invite to share the folder. That is a separate e-mail. Best, Carey On Mon, Aug 2, 2010 at 4:54 PM, <rebyl_kayak_at_energysustained.com> wrote: > Carey wrote > .........I was stumbling around in the Android Marketplace looking for cool > stuff for my phone (and I use that term "phone" loosely) and I ran across an > app for rowing that displays and records the boat acceleration and also > infers stroke rate, and some other things by using the "phone's" integrated > GPS and three axis accelerometer. It's pretty good. Both the app and my > device. .......http://nargila.org/trac/robostroke/wiki ....... > It of course does not integrate paddle dynamics, > ................................. > > G'Day Carey, > > That is very clever though I know very little about using that kind of > phone. I'm guessing it is something like an ipod and has one of those > screens that you can turn round and the image turns with you? > > Does it have Blue tooth? If so can you download the data through the > bluetooth port onto a computer? Then it would be relatively simple to time > link the data to a Talon paddle so long as they were willing to fit a blue > tooth modem to their data stream. Alternatively one could start the data > recording on both paddle and phone and then provide a synchronising single > by tapping the paddle on the kayak before and after the test run. crude but > effective synchronising. > > Any further details would be greatly appreciated? > > All the best, PeterO > > -- http://parkswhistles.com/ http://www.facebook.com/carey.parks http://twitter.com/LuthierCarey *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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