Enugu

I still haven't figured out how to use python to get the gps data

This was my reference to solving that problem

Because i have little idea how to make a gui for python, i searched the webs and came across this https://www.daniweb.com/programming/software-development/code/216785/tkinter-digital-clock-python It's code for a clock, and i used this clock code to display the strokerate i find

I really banged my head on the table when i realised those simple improvements

This'll be a summary of what the code does 1. Every 0.05 seconds: I. get acceleration data from sensor II. Calibrate acceleration data III. Apply low pass filter IV. Get summation of acceleration vectors V. If zero crossing, append time to list 2. Every 1 second I. Calculate frequency from 1.V II. Output strokes-per-minute 3. Every 1 minute or longer I. Find mean of each acceleration axis from past 10 seconds

Because each axis of the accelerometer's origin points defer depending on the orientation of the sensor (because gravity), they need to be set to zero So a "base" value needs to be found for each axis. To find this value, simply have a function that runs either every few minutes, or when it is detected that the boat is not doing any stroking. Just record the values across the past 10 seconds or so, and get the mean The values to be analysed would be the raw data value - the base value

Instead of looking at it as peak detection, it makes more sense to look at it is frequency estimation. So how to find the frequency? Previously it was suggested to do peak detection, but the problem with this is, there occasionally can be double peaks during the same stroke, also a threshold value needs to be implemented such that noise is ignored Because the number of peaks during a single stroke might not be consistent, a new method was quickly found https://gist.github.com/endolith/255291 Because the zero crossing is definite between strokes, it is a much more sound solution. And the noise can similarly be ignored by using a threshold value A bit more thought would have to be put to this before something definite arises

How to detect peaks? The sensor values might vary wildly, a threshold can be implemented such that values below a certain point are ignored Then if a certain value is more than the one before it and the one after it, it's a peak Or maybe to add on, peak if (y(t) - y(t-dt) > m) && (y(t) - y(t+dt) > m) - http://stackoverflow.com/a/22583761

So after all that, the waveform is something useable. Next is to read it, find the peaks…

The gps module i procured uses the uart protocol It took me a very long time to figure out how to read and use the data from a gps through UART on the arduino, and there only seems to be less documentation for the raspberry pi, godspeed There was a post that suggested to connect the gps module through usb instead, but that'd require an adapter, which maybe can be crudely fashioned through a spare usb cable Also, there's this guide that goes through how to read/write from the serial port http://www.elinux.org/Serial_port_programming And the following step would be to read the nmea gps protocol to spit out the relevant data The worst part about using the gps is that my home is pretty much a faraday cage with weak reception for some 10 mins walk

With c++, when i want to run a task ever N seconds, i'd use the delay function or millis function if there are multiple tasks. Thankfully, python comes with a very easy to use multithreading library http://stackoverflow.com/questions/3393612/run-certain-code-every-n-seconds

Occasionally, i have to download libraries or upload code to the cloud, all this requires internet access. Unfortunately, the raspberry pi doesn't have wifi capabilities, and requires an ethernet cable. Becomes inconvenient especially since my desktop isn't near an ethernet port So i bought a wifi dongle, and i'll be following this guide to hopefully get wifi capabilities http://raspberrypihq.com/how-to-add-wifi-to-the-raspberry-pi/

by using csv, the large amounts of data from the sensors can be read and written easily

this here post gives some examples of guis to go along with matplotlib

And lastly, an infinite loop can be used to keep writing data to the file

Thankfully, documentation on how to do so has already been provided https://www.raspberrypi.org/learning/physical-computing-with-python/analogue/

https://www.reddit.com/r/raspberry_pi/comments/65ouwu/if_it_worked_any_better_it_would_have_put_the/?st=J1Q2JXUD&sh=224e6572 This is very relevant to the project i'm doing The creator mentioned to get to know glade and gtx, so i'll have to look into those. I suppose the first iteration of my gui would look similar to that