Despite of having legislative drive cycles which represent driving pattern of the driver, the real world driving scenario may vary drastically depending upon the weather conditions, amount of traffic & driver's mental-physical health. Due to such reasons, the vehicle will give different results for greenhouse gas emissions when tested on legislative drive cycle vs. when tested on real world drive cycle.

In order to tackle this problem, an attempt was made to develop Real World Drive Cycles for regular, relaxed & aggressive driving patterns. all the 3 drive cycles followed same route while following predefined test specifications as shown in Fig.1. Following a similar approach was used as of World Harmonized Test Procedure drive cycle, this drive cycles included road passing through Urban, Motorway & Rural areas.

*Data Collection & Post Processing:

Vehicle location & speed vs. time data was collected using SpeedView android application. once data was collected, .gdx file was then exported from the application which was converted to Microsoft Excel compliant file format using GPS Visualizer file conversion tool. The data was checked for identifying any errors due to GPS signal losses & unwanted halts. As it can be seen in Fig.1, these errors were then rectified by implementing a moving average data filter & data was made usable for Tank-to-Wheel Analysis for identifying greenhouse gas emissions & fuel economy using model based powertrain simulation.

A complex model of power-split hybrid type of powertrain configuration was developed using existing GT-Suit libraries (Fig.2) & the model parameters were defined as per the specifications of EURO 4 compliant 2nd Toyota Prius THS-II powertrain. The required data was identified from the published literature & datasets available in the university. Model was validated against New European Drive Cycle while comparing the published & simulation results of Fuel Economy & Greenhouse Gas Emissions. This model is further being developed to equip a micro gas turbine range extender.

*Key Components of The Model:

1. Supervisory Controller:

This is the mind of the vehicle which receives power demand from the driver and communicates with all the vehicle subsystems to propel the vehicle in efficient manner. In simple terms, it is a in-vehicle event manager which decides the vehicle propulsion mode such as pure electric, pure combustion or hybrid mode of operation based on the power demand from the driver & battery state of charge. (Fig.3)

2. Power-split Device (PSD):

This is the most important part of this type of powertrain configuration, as it enables vehicle to use multiple power sources to propel the vehicle at the same instance. PSD is a planetary gear set of which Sun gear is connected to Electric Motor 1 (EM1) & Internal Combustion Engine, whereas Ring gear is connected to Electric Motor 2 (EM2) & final drive differential. This allows EM1 to acts as a starter motor for the engine as well as power regeneration alternator. Also PSD allows supervisory controller to use IC engine & EM2 as a combined power source to meet the  power demand from the driver in accelerating condition. (Fig.3)

A basic component based model of a conventional combustion vehicle was made using GT-Suite and component parameters were defined as per the specifications of Volkswagen Lupo car. Data for EURO 4 compliant engine's speed, torque, brake mean effective pressure & brake specific fuel consumption was obtained from available datasets from the university. The model was validated by comparing the results of fuel economy & CO2 emissions generated by the model when tested against NEDC drive cycle. Once validated the model was tested against all the major legislative drive cycles & also with real world drive cycle. (Fig.3)

*Results & Observation:

• It was observed that change in gear shifting time largely affects amount of CO2 emission for example early shifting caused higher CO2 emission in comparison to standard gear shifting strategy.

• It was observed that CO2 & NOx emissions of real world passive and relaxed driving cycle was lower than most of legislative drive cycles whereas for CO2 emission was higher and NOx was lower than NEDC for aggressive driving. (Fig.2) 

• Real world CO emissions were extremely higher than all legislative cycles except US06 which is nearly 3 times of EURO 4 standard limit of 0.50g/km. (Fig.3)

• Real world HC emissions were close to legislative cycles except aggressive driving, which has maximum amount of HC emissions.

• It was proved that Real Driving Emissions & Fuel Economy vary drastically with driving pattern and legislative drive cycle cannot provide accurate results of emissions.