Objective: Develop a smarter automobile cruise control that saves fuel.
Current cruise controls do not drive in an energy efficient manner in hilly terain. In going up a hill they accelerate hard to maintain the set speed and often even downshift to a lower gear. On reaching the top of the hill, they backoff the accelerator in order to not exceed the set speed on the downhill robbing the car of inertia it could apply to climbing the next hill.
The proposed cruise control would utilize elevation data from the cars gps navigation system in order to understand what terain lies ahead, and to drive in a way that minimizes fuel use for the coming terain. Basically, this means the CC would be smart enough to allow the car to slow as it approaches hill tops, and allow the car to overspeed on the following downgrade if it can use the excess speed for a coming upgrade. This basically allows the cruise control to follow the advice that is given in many lists on "how to save fuel". I suppose that a further refinement could utilize knowledge of the engine/drivetrain efficiency characteristics to further optimize the CC by choosing a most economical climb speed?
My car navigation system appears to have very detailed knowledge of the road system. I'm not sure if it has elevation knowledge in the map data base, but it seems to me this could be added if its not currently available.
I'd like to pursue this concept quantitatively -- if anyone knows of automobile simulation software that is sufficiently detailed to model engine/powertrain and terain, please let me know. Preferably free software :)
Gary
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Instead of a hookup to a satelite wouldn't it be more logical for the cruise control to respond to difficult terrain by being programmed for fuel economy rather than speed maintenance dependent upon the reaction of the engine to stress?
Hi Sand,I think that the difficulty with that approach is that the current cruise controls have no knowledge of the terain ahead, so they don't know if the upgrade that is just starting goes on for 500 ft or 5 miles, and when they get to the top of the hill they don't know if they should build up some speed on the downhill for the next uphill, because they don't know if there is an uphill coming, or if the just starting downhill goes on for 20 miles, in which case its unsafe to build up some excess speed. It seems like having knowledge of the coming terain allows a more intelligent driving strategy.
This idea has merit. With the onboard computer systems, On-Star, and cell phone technologies, it would be feasible to make this control system part of the onboard navigation system. The database would have to include elevation data, but that information is already available if one wants it from the Government.
Flight navigation systems already use a similar system for airplane auto-pilots.
Some of the software features might include genetic algorithms for analyzing the stretch of road ahead to produce the best gas mileage for the speed profile selected by the individual. The speed profile would be collected while the person was driving without the cruise control. Key features of their driving style would be recorded and used by the genetic algorithm so that the car would perform near their comfort zone for the given environment.
For instance, let's say the driver always drives 5 mph over the speed limit. The cruise control might get speed limit data from the database and make a corresponding adjustment. The driver might characteristically slow down depending upon the radius of a curve; slower when turning right, then left, for example.
Technology-wise, this is very doable, and desireable from an insurance point of view. Having the cruise control speed up and slow down to match posted speed limits, curves in the road, flat turns, weather conditions as sensed by the ABS system of modern cars, ...
The main problems would have to do with liabilities. If for instance, the database data did not match the actual conditions and the car attempted to speed up while a load was in the back of a truck and the increased speed blew the load out of the truck. Or the ABS system isn't working and the cruise control is used in icy conditions. Just being the devils advocate here.
This is an excellent idea and one I'm surprised the major car manufacturers haven't pursued already!