ADAMS/Car: Straight Line Acceleration Event with Initial Velocity = 0 and Throttle Demand Start at 1s

Hi All,

I'm trying to do something that seems like it should be straightforward but am running into problems.

From the article below I'm trying to modify the file "test_accel.xml" to have a zero initial velocity and to start the throttle demand at one second.

Article Detail (hexagon.com)

The resulting throttle demand is correct however the drive torque output is not correct with a large initial torque and a subsequent profile which is incorrect.

I tried reducing the pvs_engine_stall_speed=0...but that didn't help.

Does anyone know what changes would be needed to run this file with a zero initial speed and the throttle demand starting at 1s? I'm guessing the engine and clutch settings are the culprit...

joe.

0 Alexis Del Rio over 1 year ago

Hi,

What are the initial conditons for brake, throttle, clutch? Did you define these in the driver control file or you left it as default?
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0 jsph_inc over 1 year ago

HI Alexis,

Thanks for the response. I had thought that when you set the initial velocity to zero and delay the throttle to start at 1s that the vehicle would be at rest until the throttle starts.

Doesn't look like this is possible due to the engine idle speed. Can at least have the clutch engaged at t=0s.

Would be nice to have a feature in A/CAR to have the vehicle start at zero speed until the throttle is engaged.

joe
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0 Alexis Del Rio over 1 year ago

Hi Joe,

What type of Static Set-Up > Task do you have?. You can review the different options here:

Adams Car Package > Adams Car > Running Analyses > Using the Driving Machine
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0 jsph_inc over 1 year ago

Alexis I have Static Set-up -> Task = "settle"...perhaps "straight" would be better.
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0 Martin Kieltsch over 1 year ago

Imagine a real vehicle.

What happens in a stick shift car, when you stop, but don't put in neutral or put down the clutch pedal?

And exactly that happens in your sim. The engine stalls and doesn't react to further throttle demands.

What you need is at least some open-loop maneuver like:

velocity = 0

gear = 1

throttle=step(time, 1,0,1.2,100)

clutch =step(time,1,1,1.2,0)

I have an example xml attached, that you should open and check in the event builder.

Attached Files (1)

standstill_and_start.xml
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0 jsph_inc over 1 year ago

Hi Martin, sorry for the delay as I'm getting back to this now. Thank-you for the feedback and the file. Think this is what I'm looking for. joe.
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