F2008-06-176
Sentience - A Low CO2 Hybrid Vehicle with Current and Future Situational Awareness
The Sentience program has created a variant of the Ford Escape hybrid with significantly reduced CO2 emissions by using current and predicted future geographical and situational awareness to optimise the efficiency of vehicle systems. This work was undertaken with participation from innovITS, Ricardo UK, Jaguar/Land Rover (with support from Ford North America), TRL (Transport Research Laboratory), Ordnance Survey and Orange. The vehicle powertrain is unchanged from a current (USA) production Ford Escape hybrid (this vehicle is not available in Europe). To this vehicle is added GPS so it knows its current location, a wireless (GSM) link to provide the vehicle with real-time data (e.g. congestion, weather), as well as a supervisory ECU and HMI (to give flexibility during the research, they could be implemented in existing vehicle systems in a production system). The control system was developed by using a validated vehicle model and dynamic programming to find the optimum way to use the gasoline engine, 2 electric machines and battery that make up the vehicles powertrain. This knowledge was then embedded into the supervisory controller on the vehicle. The paper will briefly describe the vehicle model used and its validation. It will then describe the various data sources used and situations were the use of this data can reduce the vehicle´s CO2 emissions. This will lead onto a discussion about the amount of forward knowledge required and the impacts of its accuracy. For example if congestion can be accurately predicted ahead it may be appropriate to ensure the battery is almost fully charged before this is met. If the battery is fully charged then it cannot capture the regenerative energy that is available when the vehicle is slowed down, conversely if the battery is almost discharged then the ability to drive the vehicle at slow speed in EV mode will be extremely limited. The impact of Air conditioning within the hybrid system is also considered where occupant comfort needs to be balanced against CO2 emissions. This is important as air conditioning is a significant additional energy sink (thus indirectly it is a significant producer of CO2). It will be shown that it is possible to optimise the control strategy so that overall CO2 emissions are minimised while keeping an acceptable level of occupant comfort. Further it will be shown that by using current and predicted future geographical and situational awareness this process is made even more effective. The paper will finish by comparing the predicted improvements in CO2 emissions with those measured on the prototype vehicle over a number of representative test drives on public roads.
Session: Hybrid Powertrains I