Project: 3D Driving Model

[dcb]

Originally Posted by noeryan

ok, well you could just build the variables. I did the xlsread so I could change the excel file and it not affect the program.

That's ok for one iteration, but I'm not planning on making a habit of it. We probably need a data file format and routine that works with both octave and matlab, i.e. a csv file with csvread, not microsoft specific file formats.

[Bicycle Bob]

Perhaps what I have in mind is not easy to code, but what I'd want to try is a first run with the throttle at either 80% (just before the mixture gets enriched) or at the required cruise setting, or coasting. Ie: pretty much the way we drive. For the next iteration, I might try going from cruise to coasting a few seconds earlier in each instance, and seeing how the changes built up. Another kind of pass might look for opportunities to coast downhill, delaying acceleration until it is particularly easy. It might be necessary to run the data through several kinds of algorithms in each cycle, but the basic idea is to just change things to create a single new data set, not a sheaf. Then you compare that set to the previous one, and see where the best gains in the economy/time ratio has come about. You try more of the same on those places on the next pass, and back off to the previous setting where you hit some losers. You might need another register to see if the algorithms are working harmoniously or causing dithering instead of convergence. It might decide which one to try next, leaving some out on some passes.
Eventually, you'd get the program saying something like: OK, I can save you a buck at no time loss if you are willing to speed through the short valleys, drive slow over short hilltops, and coast sooner at lights. If you'll add a minute to your trip, I'll save you another buck in gas. If you'll give me two minutes, I can save two-fifty. . .etc.

[noeryan]

Ok I think I kinda see where you are going with it. How could you set it up for each particular route that you choose? And also, how would you set it up to find the valleys and short hills etc? Hills typically go up and down but sometimes you run into a short up then half down and back up again...
maybe I'm looking too deep at it?

DCB: The variables you are building are constant (I know that is an oxymoron..) for the route. They wouldn't change for different iterations. They are bringing in the distances of each section and the angles and such... maybe I'm missing something?

[dcb]

Have fun guys

[Bicycle Bob]

I'm thinking that the program would mostly acquire data from the car computer and a GPS, and perhaps an accelerometer. I guess that the data on the throttle opening used might make a better baseline than my suggestion of using just three throttle modes for a first iteration. If the early runs along the route encountered a lot of traffic, that would have to be recognized as transient impediments, while the system gathered information on the route. I don't think the program would have trouble over varying terrain or unevenly distributed stop signs - there is always acceleration, some period of constant speed, and then deceleration. The various algorithms would nudge the profile of throttle use during each cycle in different ways, and the program would then predict the results. I'd let it just run through all the accelerate/decelerate cycles in a route, letting it accumulate results, just as a car would with drivers of different styles, rather than trying to compare A to B at each section, and then see how that affects the next section like a chess match.

With each real run through a route, the program would get more hard data, and in between times, could run simulations against each other to come up with the best suggestions for improvements. You might want a button to tell the program if there are places on the route where its suggestion is inappropriate for "given" reasons.

[noeryan]

I like what you have on the ideas of just taking acceleration data and power used data. That would make a lot of sense. Just program individual routes and choose them to start and get data from each run. That makes a lot of sense. I'm having a rough few weeks with school and interviewing for jobs.

Obviously a job is more important at the moment than my lil side project. I haven't left! I'm just going to be in and out for a few more days.

[Tango Charlie]

No problem, neoryan. I (and I think I can say 'we') totally understand the priorities of life. Good luck with the interviews. Just be glad you're not job searching here in Elkhart county; 20% unemployment...
You've got a good start on this project and am excited to see where it may go.

[noeryan]

Hey stopping in. 20% Unemployment!?!? Whew. Thats bad. Sounds like Mr. Obama should be hearing about this.

This is way off topic but thought I'd bring it up. Warm Air Intakes... I've read a few forums where people have tried with no gains seen. Its possible that the reason people feel there may be something to it is because they notice better mileage when its warm outside. This is true because of the Cd equation involves density.

Ideal Gas Equation:

Pressure = Density*Constant(287 SI or 1716 Eng.)*Temperature(Kelvin or Rankin)

A warmer temperature with the same amount of pressure would indicate a lower density. A lower density would provide a smaller dynamic pressure thus producing less drag on the vehicle.

Quick calc's with Google.com doing my unit conversions came out to a 10% decrease in drag on a 90º F day compared to a 30º F day.

I'll be back shortly don't lose faith yet!

[Tango Charlie]

Obama was here for his first presidential press conference. At that time our unemployment rate was 15.3% The latest I've heard is 18%. So 20% was a bit of a stretch.

Warm air intakes; from what I've heard, the Saturns are about the only cars out there that consistently respond favorably to a warm air intake mod. My guess is that Saturns use a manifold air pressure sensor where most other cars use a mass airflow sensor. The MAF based system is a little more sophisticated, and is not 'fooled' by the less dense warm air. It just compensates the fuel injector pulse width and keeps on truckin'. But I haven't researched this out to determine if I'm on the right track or not (as far as Saturns having MAP systems).

[noeryan]

No job yet but back in the game!

I've been thinking of how to create this model... my earlier approach may have been wrong.

I've got an idea that might be crazy but would be pretty cool. I'd like to have the program written for the iphone. It has GPS and an accelerometer built into it. PERFECTO.

Also, I think having two sets of iteration would be better than one complicated one.

One set for the gradient, and the other set for the aerodynamic and rolling losses.

I should have realized earlier that gradient has a bigger role on the vehicle than aero at city speeds.

For example: a 5 degree downslope over a distance of 100 m. If my initial velocity is 10 m/s, i would first ignore the aero and rolling losses and calculate the energy gain and final velocity.

second, I would assume linear acceleration over the course and subtract the energy lost [ave(aero force) * distance] for the course. this could give a final kinetic energy of the vehicle and thus a more accurate velocity at the end of the course.

HOWEVER, if a more simplified method of driving was assumed. Maybe one that requires acceleration to be limited to under a certain number, the Iphone app might could be very easily put together with a little dial that measured your acceleration and warned you when you accelerated too much.

An example of driving this way seems to be efficient. Speeding up down hills and slowing down up hills. Constant velocity on flat areas. It's a little confusing to picture it working, but if you slowed down going up a hill, wouldn't the accelerometer not 'feel' all of the acceleration of gravity that's affecting the car? If you maintained constant velocity, the accelerometer would feel the acceleration of gravity but slowing down balances the forces on it I believe... ?