enviroCar

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About

enviroCar is an open platform for Citizen Science projects in the filed of sustainable mobility. Citizens, scientists, traffic planners and industry collect and analyze floating car data and share their findings.

About the project: https://envirocar.org/about.php

Project website: https://envirocar.org/

Documentation

Software projects documentation: http://envirocar.github.io/

Public API documentation: http://envirocar.github.io/enviroCar-server/api/

Technical documentation: https://wiki.52north.org/bin/view/Projects/EnviroCar

This wiki page is used for documentation of technical background. Please see the aforementioned websites for general information about enviroCar.

Community / Contact

Get involved: https://envirocar.org/about.php#getinvolved

Forum: http://envirocar-discuss.forum.52north.org/

Measurements and Calculations

Measurements

Depending on the car, not all of these are available. Prior to requesting any data, PIDSupported commands (01 00, 01 20) are issued in order to retrieve the PID capabilities of the car.

Once the list of available PID commands is retrieved, the app requests the following commands periodically:

• Calculated engine load
  • Request: 01 04
  • Reponse: 1Byte = A * 100/255 percent
• Intake manifold absolute pressure (MAP)
  • Request: 01 0B
  • Response: 1Byte = 0 .. 255 kPa (absolute)
• RPM
  • Request: 01 0C
  • Response: 2Bytes = (( A * 256) + B) / 4 = 0 .. 16383.75 rpm
• Speed
  • Request: 01 0D
  • Response: 1Byte = 0 .. 255 km/h
• Intake air temperature
  • Request: 01 0F
  • Response: 1Byte = A-40 = -40 .. 215 °C
• MAF (Air flow rate)
  • Request: 01 10
  • Response: 2Bytes = ((A + 256) + B) / 100 = 0 .. 655.35 grams/sec
• O2S1_WR_lambda
  • Request: 01 24
  • Response: 4Bytes; ER = ((A*256)+B)/32768; Voltage = ((C*256)+D)/8192 V
• O2S1_WR_lambda
  • Request: 01 34
  • Response: 4Bytes; ER = ((A*256)+B)/32768; Current = ((A*256)+B)/32,768 mA

Get a comprehensive documentation of all existing OBD-II PID commands here.

Fuel consumption and CO2 emission are derived from a subset of the previously listed PID responses. See EnviroCar for details. In addition to the PIDs from car, GPS parameters from the mobile device (Speed, Accuracy, Bearing, ...) are recorded.

Calculations

calculated MAF

this happens when the OBD adapter delivers no result for MAF:

• IMAP = RPM * MAP / IAT
  • RPM
  • MAP - Manifold Absolute Pressure in kPa
  • IAT - Intake Air Temperature in Kelvin
• MAF = (IMAP/120)*(VE/100)*(ED)*(MM)/(R)
  • R - Specific Gas Constant (8.314472 J/(mol.K)
  • MM - Average molecular mass of air (28.9644 g/mol)
  • VE - volumetric efficiency (most modern cars have a value of 80% to 85% - we use 85% in the app)
  • ED - Engine Displacement in liters

https://github.com/oesmith/obdgpslogger/blob/master/doc/mpg-calculation

http://opengauge.googlecode.com/svn/trunk/obduino/obduino.pde

http://www.google.com/patents/US20060069490

Consumption

Gasoline engine

• MAF / AFR => grams/second
  • MAF = Mass flow air in grams/second
  • AFR = Air fuel ratio ( Mass ratio of air to fuel)
    • Gasoline has 14.7
    • Diesel has 14.5
• MAF / AFR / Density of fuel => liter/second
  • Density of fuel:
    • Gasoline has 745 grams/liter
    • Diesel has 832 grams/liter
• MAF / AFR / Density of fuel * 3600 => liter/hour

Diesel engine

Fuel consumption for diesel engines is more complicated then for gasoline powered engine. See the dedicated subpage for details: DieselConsumptionCalculation

App

App Compatibility

The following compatbility between OBD-II-Adapters and Android device models has has been assessed. Feel free to contribute, preferable also informing the community on the mailing list (http://envirocar-discuss.forum.52north.org/ - or via email envirocar-discuss@52north.org).

Matrix

(Android Device) / (OBD-II Adapter)	Low-cost China import from eBay/Amazon	Apos BT OBD 327	Apos BT OBD W3	DriveDeck Sport (W4)	OBDLink MX	"Mini ELM327 OBDII Interface"	...	...
Google Galaxy Nexus (Android 4.3)
Google Nexus 7 (Android 4.3)
SE Xperia X10 Mini Pro (MiniCM7, Android 2.3.7)
Sony Xperia Z (Type PM-0270-BV, Android 4.1.2)
Samsung S 3 Mini (Android 4.2.2)
Google Nexus 4 (Android 4.3)
...
...
add you experiences here ...

Status: = to be done, = somebody is working on it, successfully tested (second reports welcome!), = did not work (second tests welcome!).

More enviroCar wiki pages

enviroCar ArcMap Client

enviroCar Dissemination

enviroCar Testing

WPS Implementation

Archive

Guidelines Beta Test Phase