First threshold to classify “good” and “bad” roads

After visualizing the sensor data of a 25 time frame (from our first test drive) which contained both, good and bad quality roads we decided that the road quality can be extracted by only using the “z-acceleration” – at least for a first threshold to classify between two simple qualities: “good/okay” and “(really) bad”.

(The green section in the first chart marks a good quality road, the blue sections a “normal” quality road and the red section a “(really) bad” quality road.)
accel-and-marks

For references: charts for gyroscope and rotation data:
gyro

rota

 

Finding a first threshold

Then we combined our road quality notes of the first test drive with the “Z-acceleration” data of the whole test drive and decided to use 1.4 as a threshold to differentiate between regular quality and “pothole measurements”:

21:49 “bad road”
received_2015-06-24_19-42-13

20:52 “really bad road”
received_2015-06-24_18-51-17

21:05 “quite good road”
received_2015-06-24_19-00-38

21:23 & 21:25 “really bad road”
received_2015-06-24_19-18-59

Testing the current state of the messbox

After working on the server-PI and sensor-PIs separately and often virtualized we decided that it’s time to put the messbox together and see what happens.

iot_glue_setup

The PIs boot and connect automatically. The sensor-PIs directly start sensing and forward the data to the server-PI who reads the GPS data and writes the received sensor data to csv files as soon as all sensors are connected.

iot_glue_screenshot

Here you have a sample csv log file which contains a quake around the timestamp 707020657 (line 844): sample csl file

The format of the csv file is:

sampleID, timestamp, sensorName (GPS), time, lat, lon, speed, course.
sensorName (FL), gyroX,gyroY,gyroZ,acceX,acceY,acceZ,rotaX,rotaY,rotaZ,
sensorName (FR), gyroX,gyroY,gyroZ,acceX,acceY,acceZ,rotaX,rotaY,rotaZ,
sensorName (BL), gyroX,gyroY,gyroZ,acceX,acceY,acceZ,rotaX,rotaY,rotaZ,
sensorName (BR), gyroX,gyroY,gyroZ,acceX,acceY,acceZ,rotaX,rotaY,rotaZ,
measurementID

And here a chart of the test quake:

received_2015-06-07_19-56-44_chart