ADAMS Car Road Builder

[Jim Jones]

Hello! I'm a 2nd year Mechanical Engineering student in FSAE at my college and our team is trying out ADAMS Car for simulations. We've been using it a lot more since its free for us and machine shop hours have been highly limited due to COVID restrictions. We have a working car assembly, and we just need to have a road/event file to test it on.

I am trying to use ADAMS Road Builder make the road as realistic as possible to our physical test track. But I am finding road builder a bit hard to understand due to the lack of in detail help guides for road builder help folders. I understood the linear segment and that was about it...making even a basic circle was a fail for me when testing out user functions. And the road I am trying to model which is in real life has some complex curvyness.

Rather than using road builder, I did see that the road points can be imported as X Y Z coordinates -- I'm wondering if I could manually take some points and just place them in a excel file, and import that into the road points? After that I can use the obstacle builder to put some bumps in.

I plan personally drive to our FSAE test track physically, and take some X Y Z measurements in meters and record them. With enough points would this method work? None of my other team members are very sure, so I just hope I don't waste my time with this method because it will take me a while to drive there and get back and even more time to record the points... Unfortunately, I am not sure of any other ways to do this. Any tips and advice is appreciated before I am off to drive and get those points haha...

 

[GregLocock]

Can you explain what you are trying to do? Typically I just use witches hats for visualization and a custom routine for generating open loop swa commands to generate a path which is then tested for compliance with the track limits, for the moose test. Have you looked at the help for Path optimization?

Cheers

Greg Locock


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[GregLocock]

There is a file imola_track.drd which is closed loop The syntax is very simple.



Cheers

Greg Locock


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[Jim Jones]

So my/our team's goal is to create a road file that very closely resembles our real life physical test track. And then use the full vehicle analysis event builder -- event file smart driver to drive the car around the road which we will then compare with a real world test drive.

I am kinda a beginner at this and I have not heard of .drd/witches hat/swa commands. I do see the imola_track.drd file in adams, but I do not have path optimization help files in help (I searched path in help file and only some .png files showed up).

I was working off of and learning about using .xml files because when I open road builder there is a default road file called: mdids://acar_shared/roads.tbl/3d_road_obstacle_sine.xml
This seems to be a straight line road with a sine obstacle, and the real world road is kinda similar -- except it is closed loop and more complex curves and elevations. Like you could imagine a curvy circle with obstacles it has to pass. I am trying to make a .xml road file of this.

I can try to investigate the .drd/swa stuff you are mentioning if you think that is the way to go though. The problem I am having with the .xml as mentioned for me is to try and make user functions/ get X Y Z road points around the track (because I am going to have to physically measure the real world track).

 

[GregLocock]

Path optimization is a tutorial in the /car help

Witches hats are just graphical models of cones used to define the perimeter of the track for visualization.

There's two approaches - path optimization on a defined path, which is what the tutorial talks about, or an open loop event where you feed in time histories of swa and vx from a real lap, and then if your correlation is perfect the car will create the path that matches the track. You'd build that as a mini maneuver in event builder. the latter is what I'd call a data driven event and is what a lot of correlation work uses. So we supply identical inputs to the real car and the model, and then compare things like roll angle, lateral acceleration and yaw velocity.

Cheers

Greg Locock


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

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[Jim Jones]

I think I now see what you mean -- the path optimization is some pretty cool stuff. I am still on step 1 because path optimization needs a defined road path. Which in my case is the road file which I still need to make. I need to take real life track measurements and build the road before running any simulations. Making the road/path file is the part I was having trouble with but I assume you would just use the road builder?
I know you mentioned custom routine for generating open loop swa commands but I do not know what this means. Are there any tutorials that I should look for this? Thanks.
Once this works hopefully the end goal is as you said where I can look at roll angle etc.

 

[GregLocock]

No, don't worry about that, that's what I use for path optimisation for the moose test and nothing else. I've only done tutorials in /Car it is not my program of choice, so I'm not going to be much help. But basically for a data driven event you need to feed in a time history of SWA and VX. or you can do path optimisation. They are completely different approaches. DDE is great for correlation, PO might be great for assessing tweaks to your car to improve performance.


Cheers

Greg Locock


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