Lap Simulation

[bl79]

I wasn't sure if this should go here or in other topics but I figure you folks must know something about simulation.

I am interested in utilizing a lap simulation software for my Formula SAE team. The main use this program would see is to justify decisions and give our team direction. For example, how does 10% increase in power affect our lap times and points? How does a 10% decrease in weight affect our times and points? Would the increased load from aero significantly decrease our times? etc. These sims could then be used to justify the addition of a turbo or going to a single cylinder engine vs 4 cylinder etc.

We don't need a F1 level simulation software, but we need something that can tweak the major variables of concern to us on a track we can define(essentially autox):
Power, and possibly powerband?
Weight
Tire mu, possibly dynamic
Cd
Frontal Area
and it wouldn't hurt to be able to change track width, cg, wheel base, know fuel consumption and some other parameters.

What I've come to seek advice on is if anyone has any experience with Bosch Lapsim(there is a noticeable lack of information) or similar software(such as chassissim). I have been toying with the idea of writing a simulation myself in matlab. A few teams have done this but I would have to learn a lot in matlab and I think it would take a bit. I figure why reinvent the wheel if someone has already done the work for me.

Essentially, to anyone who has worked with these programs are they capable of doing what I seem to be asking?

 

[GregLocock]

LapSim is great, and ideal for the sort of study you are interested in. It is written in Matlab I think. It will do as you ask except fuel consumption, but you'll need the full version to enter alternate circuit layouts easily.

If you FSAEers still get access to ADAMS then there is a laptime optimiser in that, I've never used it in anger.

If you watch how Lapsim works you'll realise that writing your own is not impossible, especially if you ignore the bells and whistles like Pacejka style tire models and just use friction circles. Whether that is a good use of your time is a separate question.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[bl79]

Thanks for the response,

That sounds great then. It is nice that a program can do what we want for free. I could probably write my own but I am not the best person on the team to do it and it would be nice to have simulations by the start of the school year so major decisions can get the green light ASAP.

One other question(There really isn't that much info on google about lapsim, go figure), I read somewhere hinting that lapsim needs to run a full start to finish lap in order to function. As in point a to b rallys and a drag race wont work, is this correct?

 

[GregLocock]

The full version is not free. You will find it rather difficult to enter your own circuits in the free version.

Yes, the main module only runs full laps. It works forwards and backwards from each apex. It also has a straight line performance predictor.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[bl79]

Thanks for the input, I just got a installation number so I can give it a shot. I figure its hard to beat for free so might as well see what it can do.

One question. I'm having trouble installing it with windows 7. I go to run the msdinstall and after a bit it comes up and tells me "install not complete" and then I have no option but to exit. I tried restarting, redownloading etc but have had no luck. Thoughts?

 

[PAG24]

If you know a bit of matlab it really isn't that hard to create your own, I designed one but it took about two months. And two months in SAE time is too much. The hardest part of designing your own (well for me anyways) wasn't the actual calculations because there fairly straight forward but implementing a track design feature.
I've attached a picture of the main page so you can see what its like.