Project: 3D Driving Model

[noeryan]

DCB: I can't log altitude per second due to GPS's inaccurate altitude readings. I can't even stay still with my GPS and it read a constant altitude and when I do, it would be about 100 feet off. I used a topographical map to determine the slopes for each section... Here is a baby situation for version 1.1:

From rest at red light -> 110 m with flat ground acceleration to just under 30 mph using constant 1000 N from engine -> 70 m with 2.5º incline no engine deceleration to ~22 mph -> 90 m with 1.5º incline no engine deceleration to ~15 mph. At this point, I brake to stop for my turn. (braking because 15 mph is ssslllooooowwww)

Total distance: 270 m (.1677 miles)
Total time: 35 seconds

Average MPH: 17.2
Average MPG: ~50*

*This calculation was determined by assuming 125000 BTU per gallon -> 131881982 joules per gallon.
Used 1000 N for 110 m = 110000 joules / .25 (eng. effiency) = 440000 joules
440000 joules / 131881982 joules per gallon = 0.00334 gallon
0.1677 miles / 0.00334 gallon = 50.2 MPG

NOTE: This does not take into account engine idle consumption because I do not know what my particular vehicle's consumption rate is. Nor do I worry about something so simple just yet in the calculations. I'm merely getting a grasp as to what it takes to iterate the best MPG in this situation...

Anyone know of some coding tools in Excel other than IF statements...? I'd rather do loops in a single cell and bundle the calculations.

CHECK OUT THE v. 1.1 below along with route1.
If it seems confusing, PLEASE ask questions and I'll explain.

[dcb]

I think that topography data you are hoping to work from is too coarse, and the timing of the lights and other obstructions is impossible to get a handle on.

I do however think a vehicle equipped with a handful of sensors could be driven over the course and allow more accurate predictions about how to drive that specific course next time, but the data generally available online is not accurate enough to lend itself to accurate throttle position recommendations.

I did like the hill testing approach though. Adding in powered acceleration introduces enough additional variables that it is worth it to make sure the model is accurate without it. But you need a detailed profile of said hill, which at this point looks like it would take a tape measure and an inclinometer

[noeryan]

I dunno, the total distance of the trip is about 2.4 miles... did you see the number of data points I'm working with in the Route1 file? I can visualize the entire trip and it seems fairly accurate. In a vehicle, a 10 foot inclination isn't really all that much.

I'm using what I can get my hands on for free right now, plus I'm taking this one step at a time. Its easy to sit back and dream about sensors and cameras but like DCB stated earlier, getting your hands dirty is the hard part. I'll be back to school tonight and plan on starting some of my MATLAB coding of the project. I'll be able to iterate a force through the trip at each section (i.e. use 100 N in each section, then 200 in each section, if it goes over then drop it to 150 etc.) automatically.

I'm diggin the pulse and glide method that TestDrive asked about earlier. I think since an engine's Power consists of it's force*velocity(rpm) that running the engine w/ a lot of force for a short amount of time is much better than running with little force for the entire trip.

When we accelerate, the RPMs go up but our acceleration stays the same meaning the same amount of force is coming out of the vehicle's engine though more revolutions thus more fuel is being spent. Because of gearing, the amount of force that can be applied at a particular velocity seems to be between whatever gear we are in or any gear we could downshift to... I don't even know why I'm worrying about this now. More diff. eq. and hills. I'll be searching for the least amount of energy used... that's how I'll decide the best MPG. I've stated my engine is .25 efficient so all of the energy needed is multiplied by 4 to state how much energy in fuel I've had to burn to achieve this.

[noeryan]

I've edited the Route1 file to Route1_1 and added a data series of the entire trip of x distances so I could chart the route. Its pretty cool looking I can't lie

Its pretty accurate too. The Red Dots are the stop signs or red lights. Maybe this will give a few of you a better look at whats going on.

[dcb]

Originally Posted by noeryan

...
When we accelerate, the RPMs go up but our acceleration stays the same meaning the same amount of force is coming out of the vehicle's engine though more revolutions thus more fuel is being spent.

The torque curve for an internal combustion gasoline engine in your typical vehicle is anything but flat, and varies dramatically from vehicle to vehicle. There are plenty of examples online, but it is also the top line on most of the bsfc charts here too:
http://ecomodder.com/forum/showthrea...-got-1466.html

[noeryan]

Thanks DCB. Adding that variable into the equation right now would destroy my baby program. Thanks for pointing that out though.

[dcb]

You might find this thread interesting too:
http://ecomodder.com/forum/showthrea...uter-5218.html

But if you can live with pulse and glide and a stickshift, the bsfc charts really simplify the throttle position question.

[Bicycle Bob]

That engine output graph is just for maximum output at a given RPM. We also need information on part-throttle operation, and efficiency. Rather than research all the engine types, and estimate their state of tune, it is probably better to interface with the MPGuino data. From that, and the GPS position data, a rough guess at elevation changes could be made. Adding an accelerometer would help with accuracy and filtering out wind effects. I wonder if you can get an input for current weather data to check on wind, rain, snow, temperature, etc.

[noeryan]

Thanks Bicycle Bob,
That makes much more sense. I was racking my brain trying to figure it out... it just didn't make sense to me but I thought maybe I was missing something.

[dcb]

Well, excepting for enrichment, your engine is most efficient with the throttle plate wide open. It's a big part of the reason diesels get good mileage.