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Steering Simulation (Adams Car)

thread823-474823

Steering Simulation (Adams Car)

Steering Simulation (Adams Car)

(OP)
Hi.

I am new to Adams Car software and have been solving this error for few days but the error is still there.
I used fsae 2018 template to create an assembly of front suspension and steering (changing coordinates). The simulation for front suspension subsystem can be run but when it comes to the assembly with steering, it keeps failing and I have no clue on what is causing this error.

Does anyone know what is the error? Thanks in advance for your help.

Error is attached here:
Begin Static Solution


STATICS: Original static solver will be used with the Sparse linear solver.

Static Solution converged in 4 iterations
Residual imbalance is less than 4.89097E-10

End Static Solution
Begin Simulation

****** Performing Quasi-Static Simulation ******
Simulation Step Function Cumulative CPU Slvr
Time Size Evaluations Steps Taken time type
___________ ___________ ___________ ___________ ________ ___
0.00000E+00 0.00000E+00 0 0 0.16 1
1.00000E-01 1.00000E-01 11 2 0.17 1

End Simulation
Begin Simulation

****** Performing Quasi-Static Simulation ******
Simulation Step Function Cumulative CPU Slvr
Time Size Evaluations Steps Taken time type
___________ ___________ ___________ ___________ ________ ___
1.00000E-01 1.00000E-01 11 2 0.17 1
2.00000E-01 1.00000E-01 15 3 0.17 1

End Simulation
Begin Simulation

****** Performing Quasi-Static Simulation ******
Simulation Step Function Cumulative CPU Slvr
Time Size Evaluations Steps Taken time type
___________ ___________ ___________ ___________ ________ ___
2.00000E-01 1.00000E-01 15 3 0.17 1
3.00000E-01 1.00000E-01 20 4 0.19 1

End Simulation
Begin Simulation

****** Performing Quasi-Static Simulation ******
Simulation Step Function Cumulative CPU Slvr
Time Size Evaluations Steps Taken time type
___________ ___________ ___________ ___________ ________ ___
3.00000E-01 1.00000E-01 20 4 0.19 1
4.00000E-01 1.00000E-01 27 5 0.20 1

End Simulation
Begin Simulation

****** Performing Quasi-Static Simulation ******
Simulation Step Function Cumulative CPU Slvr
Time Size Evaluations Steps Taken time type
___________ ___________ ___________ ___________ ________ ___
4.00000E-01 1.00000E-01 27 5 0.20 1
5.00000E-01 1.00000E-01 37 6 0.22 1

End Simulation
Begin Simulation

****** Performing Quasi-Static Simulation ******
Simulation Step Function Cumulative CPU Slvr
Time Size Evaluations Steps Taken time type
___________ ___________ ___________ ___________ ________ ___
5.00000E-01 1.00000E-01 37 6 0.22 1


Time: 5.506694744E-01.
QSTATIC: Step Size Too Small: 6.021792680E-06

End Simulation

Simulation failed

Begin Simulation

****** Performing Quasi-Static Simulation ******
Simulation Step Function Cumulative CPU Slvr
Time Size Evaluations Steps Taken time type
___________ ___________ ___________ ___________ ________ ___
5.50669E-01 6.02179E-06 38831 56 0.22 1


Time: 5.506694744E-01.
QSTATIC: Step Size Too Small: 9.114411965E-06

End Simulation

Simulation failed

Begin Simulation

****** Performing Quasi-Static Simulation ******
Simulation Step Function Cumulative CPU Slvr
Time Size Evaluations Steps Taken time type
___________ ___________ ___________ ___________ ________ ___
5.50669E-01 9.11441E-06 40001 56 0.22 1


Time: 5.506694744E-01.
QSTATIC: Step Size Too Small: 1.521792759E-05

End Simulation

Simulation failed

Begin Simulation

****** Performing Quasi-Static Simulation ******
Simulation Step Function Cumulative CPU Slvr
Time Size Evaluations Steps Taken time type
___________ ___________ ___________ ___________ ________ ___
5.50669E-01 1.52179E-05 41171 56 0.22 1


Time: 5.506694744E-01.
QSTATIC: Step Size Too Small: 2.132144321E-05

End Simulation

Simulation failed

Begin Simulation

****** Performing Quasi-Static Simulation ******
Simulation Step Function Cumulative CPU Slvr
Time Size Evaluations Steps Taken time type
___________ ___________ ___________ ___________ ________ ___
5.50669E-01 2.13214E-05 42341 56 0.22 1


Time: 5.506694744E-01.
QSTATIC: Step Size Too Small: 2.742495884E-05

End Simulation

Simulation failed



Begin Static Solution


STATICS: Original static solver will be used with the Sparse linear solver.

Static Solution converged in 1 iterations
Residual imbalance is less than 9.37210E-08

End Static Solution
command: simulate/static, end=31.000000, steps=30
Begin Simulation

****** Performing Quasi-Static Simulation ******
Simulation Step Function Cumulative CPU Slvr
Time Size Evaluations Steps Taken time type
___________ ___________ ___________ ___________ ________ ___
5.50669E-01 0.00000E+00 0 0 1:15 1


Time: 5.506694744E-01.
QSTATIC: Step Size Too Small: 6.194932154E-05

End Simulation

Simulate status=-124

command: !
command: stop

Termination status=0

Terminating Adams Car usersubs...


Finished -----
Elapsed time = 77.35s, CPU time = 77.34s, 100.00%

Analysis failed!
Please check the error messages to determine the cause.

RE: Steering Simulation (Adams Car)

Can you post the acf or dcf of the event. It looks as though the model is running ok for the first 4 sub events but is then being asked to do something odd.

also look at the graphics, and the plots. I'm assuming the standard FSAE model runs this ok?

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: Steering Simulation (Adams Car)

(OP)
Hi, Greg Locock. Thanks for your reply.

Yes, the standard FSAE model can be run without error.

I am not able to view the graphics and plot for my simulation because it failed.

Here is the acf of the steering simulation under suspension analysis.


file/model=test_steering
!
!INFO Adams Version: Adams 2020 FP1
!INFO Adams Build: 2020.1.0-CL748966
!INFO Assembly File: <private>/assemblies.tbl/FSAE_STEERING_GEOMETRY.asy
!INFO Solver Library: C:/PROGRA~1/MSC~1.SOF/Adams/2020_1~1/win64/acar_solver.dll
!
preferences/solver=CXX
preferences/list,status=on
control/ routine=acarSDM::con950, function=user(950,35,37,1,2,18,20,1,3,2,3,34,36,2,3,34,36,1,1,0,0,0)
simulate/static, end=501.000000, steps=500
!
stop


Looking forward to your reply. Thanks in advance.

RE: Steering Simulation (Adams Car)

That's a fairly uninformative acf unfortunately. I'm surprised you can't see the graphics, have a poke around in the folder and look for a .gra file.

Can you start from the model that runs and then swap in one of your sub assemblies at a time until it breaks?

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: Steering Simulation (Adams Car)

(OP)
Hi Greg Locock. I have solved that issue. Thanks for your help.

May I check with you the definition of the variable in plotting the graph?
1.Ackerman is the difference between the left and right wheel steer angles.
2.Ackerman angle is the angle whose tangent is the wheel base divided by the turn radius. 
3.Ackerman error is the difference between the steer angle and the ideal steer angle for Ackerman geometry.
4.Ideal steer angle is the steer angle in radians that gives Ackerman steer geometry or 100% Ackerman.
6.Percent Ackerman is the ratio of actual Ackerman to ideal Ackerman expressed as a percentage. 

These are the definitions that I got online. However, for percent Ackerman, I don't understand its meaning. What is the difference between actual Ackerman and ideal Ackerman? What info can be derived from this variable? When I am looking at the graph, it just makes no sense to me.


Looking forward to your reply. Thanks in advance.

RE: Steering Simulation (Adams Car)

So parallel steer is 0% Ackerman, and (2) and (4) is 100% Ackerman. So %ackerman=(finner steer-fouter steer)/ideal_ackerman*100%. Unless you are designing carriages for gravel driveways you don't normally want 100% Ackerman. Best discussion I know of for Ackerman for production cars is in Reimpell and Stoll.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: Steering Simulation (Adams Car)

(OP)
Hi Greg Locock.

May I know what is finner steer and fouter steer?

Thanks

RE: Steering Simulation (Adams Car)

(OP)
Hi Greg Locock.

I see. So, for ideal ackermann in the equation %ackerman=(finner steer-fouter steer)/ideal_ackerman*100%, is it equal to ideal Finner angle- ideal Fouter angle?

Thanks in advance.

RE: Steering Simulation (Adams Car)

(OP)
Hi Greg Locock.

Got it. Thank you so much for your help. Have a nice day.

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