It is 0:46am and i can proudly announce that after two days of reparing small mistakes in a program, after 5 hours of processor calculating and after a few laps in LFS i have working alpha software to determine gear ratios in the gearbox. 
well the program is still far away from done, but it works!! and it actually finds balance between to short or to long gearbox...
I am so f***** happe
well the program is still far away from done, but it works!! and it actually finds balance between to short or to long gearbox...
I am so f***** happe
OK here it is... one WR file
data in here are even worse that i described above.
Please see the RAF at the 43rd s where the altitude is constant.
:S sorry i missed unspring mass in .bin file
data in here are even worse that i described above.
Please see the RAF at the 43rd s where the altitude is constant.
:S sorry i missed unspring mass in .bin file
Last edited by GrEgce, .
I read total car weight from RAF (1012.xxx kg) as i know this shlould be right for FXG at WR lap.
and if i sum all wheel loads i get 860kg. So there is 150kg missing...
there is a chance that this perpendicular loads are suspenssion loads, then i have to add 20kg for every wheel and unknown value for suspansion weight. But at the end there are still just 940kg...
well this is not so extremly important as i use this to calculate rolling resistance. but it is a little strange.
and if i sum all wheel loads i get 860kg. So there is 150kg missing...
there is a chance that this perpendicular loads are suspenssion loads, then i have to add 20kg for every wheel and unknown value for suspansion weight. But at the end there are still just 940kg...
well this is not so extremly important as i use this to calculate rolling resistance. but it is a little strange.
One more question
how come that perpendicular wheel loads summed together are not the same sa car weight on the flat area?
this gives no sense... this means that system is not stable and the car is falling with acceleration (on flat area!!)?
and why do left wheels have different sign than right? (in RAF)
how come that perpendicular wheel loads summed together are not the same sa car weight on the flat area?
this gives no sense... this means that system is not stable and the car is falling with acceleration (on flat area!!)?
and why do left wheels have different sign than right? (in RAF)
Exacly!
Even more complicated!
The program reads RAF of your (best) lap and determines locations and distances of streight accelerations and it builds database with straight lengths, its starting speed and its ground level properties. that means that program is reading driving stile properties of the driver and properties of the track.
Then this data base is used to find the fastest gearbox setup with "millions" of different tests.
This is my program in short. I am pleased that you invited me to particiapte in a bit of VHPA project, and i will give the program to LFS public... the only problem is, that i am using LabVIEW to write a program, as i am an Mechanical Engineer not a Programmer by profession
so as for now there is no C, c++ or other konwn translater from LabVIEW 
Even more complicated!
The program reads RAF of your (best) lap and determines locations and distances of streight accelerations and it builds database with straight lengths, its starting speed and its ground level properties. that means that program is reading driving stile properties of the driver and properties of the track.
Then this data base is used to find the fastest gearbox setup with "millions" of different tests.
This is my program in short. I am pleased that you invited me to particiapte in a bit of VHPA project, and i will give the program to LFS public... the only problem is, that i am using LabVIEW to write a program, as i am an Mechanical Engineer not a Programmer by profession
so as for now there is no C, c++ or other konwn translater from LabVIEW so every thing is as it says tnx mate, once again
i hope that, i ll be able to introduce alpha version soon!!!
Dammed i am dumb!!!
i just dont get it how did you manage get CdA form CAR_info.bin file (or at all)
***************************************************
// Now 4 aero blocks - rear wing, front wing,
undertray, body : 20 bytes each)
128 Position : x, y, z
Lift : multiply by speed squared to get lift value
Drag : multiply by speed squared to get drag value
***************************************************
for XFG
if i read this at Offset 188+4 (192) i get 0,4. And as it writes above... i should multiply 0,4 by speed squared...
But if i look at VHPA... it writes 0,66 for CdA
what am i dooing wrong??
dragforce=CdA*v^2 (1)
dragforce=Cd*A*v^2 (2)
dragforce=C*A*r/2*v^2 (3)
As i understand that i should use only the equation (1)
i just dont get it how did you manage get CdA form CAR_info.bin file (or at all)
***************************************************
// Now 4 aero blocks - rear wing, front wing,
undertray, body : 20 bytes each)
128 Position : x, y, z
Lift : multiply by speed squared to get lift value
Drag : multiply by speed squared to get drag value
***************************************************
for XFG
if i read this at Offset 188+4 (192) i get 0,4. And as it writes above... i should multiply 0,4 by speed squared...
But if i look at VHPA... it writes 0,66 for CdA
what am i dooing wrong??
dragforce=CdA*v^2 (1)
dragforce=Cd*A*v^2 (2)
dragforce=C*A*r/2*v^2 (3)
As i understand that i should use only the equation (1)
So you are using filtered power curves that you paste them on link above in your VHPA?
Till now I was using your curves digitalized from VHPA graph
I know that engine modeling in LFS is far more than just a curve… it should be a whole system, but still there is some logic of how it works. And it is still far simpler than real engine (no or small temperature relations, no wear, no fuel regulation, no air properties…)
Tnx Bob for your help!!
Till now I was using your curves digitalized from VHPA graph
I know that engine modeling in LFS is far more than just a curve… it should be a whole system, but still there is some logic of how it works. And it is still far simpler than real engine (no or small temperature relations, no wear, no fuel regulation, no air properties…)
Tnx Bob for your help!!
Hi BOB you speed me up tnx for link... i read a little further...
Depending on discussion here: http://www.lfsforum.net/showthread.php?t=18710 and your last answer. i can gather that you still didn’t get polynomial constants for power curve :S
:S J if that is truth!?!? That Bobs VHPA uses only estimated power curve, than any useful program to calculate gear ratios can be just our wet dream!!!!
“I build my own dynos for engines and I know that just a small power curve modification, in setup range, can make huge change in gear ratios… so therefore we prepare engines setup separately for every different track, driver, and grip!!”
I hope that programmers of LFS will provide us engines power curve properties, and save me a lot of programming to build my dyno for LFS engines too. Because it would be nonsense to calculate back must constant values. :S
And again… I don’t want to be rude, I am using LFS because it is the best simulator and because it has very good support!!!!
“I build my own dynos for engines and I know that just a small power curve modification, in setup range, can make huge change in gear ratios… so therefore we prepare engines setup separately for every different track, driver, and grip!!”
I hope that programmers of LFS will provide us engines power curve properties, and save me a lot of programming to build my dyno for LFS engines too. Because it would be nonsense to calculate back must constant values. :S
And again… I don’t want to be rude, I am using LFS because it is the best simulator and because it has very good support!!!!
Power curve engine
Hi all
I am developing software to automatically calculate the best possible gear ratio, depending on track properties, car setup and drivers driving stile.
Well, I have already built that software and I am using it on racing go-karts, and some cars, but if I want to improve it even more, I need to do a lot more testing on track… or just use LFS and its telemetry output. I can read LFS binary files… but I could not find information of PoweCurve of cars engines (kW/RPM, HP/RPM, Nm/RPM…) directly in file.
So where can I get engines porwecurve characteristics? And how are they connected with throttle and turbine pressure at turbo engines.
Thanks for help
GrEgce
I am developing software to automatically calculate the best possible gear ratio, depending on track properties, car setup and drivers driving stile.
Well, I have already built that software and I am using it on racing go-karts, and some cars, but if I want to improve it even more, I need to do a lot more testing on track… or just use LFS and its telemetry output. I can read LFS binary files… but I could not find information of PoweCurve of cars engines (kW/RPM, HP/RPM, Nm/RPM…) directly in file.
So where can I get engines porwecurve characteristics? And how are they connected with throttle and turbine pressure at turbo engines.
Thanks for help
GrEgce
Hi, i have been reading your discussion because i have similar interests in usage of LFS as henningo. That is simulator for preliminary developing professional racing equipment.
The case is, that we are trying to get on-track DATA in real form without real track driving (racing). That includes noises, track bumps, wind forces and so on. This is why the wheel speeds are so interesting for henningo. He is working on modern traction control system.
TIP to get wind force:
***********************************************************************
This is a math fitting procedure and it is quite accurate. I am using this procedure to define a wind force and homemade dyno correction factor for go-karts and in future on prototype Radical.
Fw....as wind force [N]
A......front surface area [m^2]
Cx....something like drag coefficient [/]
V......speed in [m/s]
ra.....density of air [1,3 kg/m^3]
(1) Fw = A*Cx*V^2*ra/2
As A and Cx are very hard to define it is best to put them both in constant....
C1 = A*Cx [m^2]
(2) Fw = C1*V^2*ra/2
As the engine power diagram is known (kW/RPM) (you should also get it for LFS car) it is possible to determine the force that the car has on the drive wheels.
P…..engine power [kW]
M….engine torque [Nm]
Fe…force of engine on drive wheels [N]
w….engines speed [rad/s] (not RPMs) w = 2*pi*n
i…...transmission [i] including driving gear, primary transmission, differential….
r…..dynamic radius of driving wheels [m]
(3) P = M*w
(4) M = P/w
(5) Fe = P/(w*r)*i
Now that the forces Fe and Fw are on the same level it is possible to write balance equation.
a……acceleration of the car [m/s]
m….mass of the car [kg]
(6) 0 = Fe-Fw–a*m
(7) a = (Fe-Fw)/m
Now it is able to compare cars speed form telemetry (on car or LFS RAF file) and mathematically determined one.
V…. speed of car [m/s]
Vo.. staring speed [m/s]
t….. elapsed time [s]ž
(8) V = Vo+a*t
Compiling equations (2), (5), (7) and (8) results mathematical model for fitting wind force constant C1 (9)
(9) V = Vo+(P/(w*r)*i-C1*V^2*ra/2)/m
Using either hand editing C1 and inspecting graph plot fitting or using one of mathematical fitting methods that are included in LIBs should be just a programming routine from now on.
***********************************************************************
I should thank to all of you for hi-level discussion and superb help on the LFS forum.
I prefer LFS as my shelter from ended racing driver career!!!!
The case is, that we are trying to get on-track DATA in real form without real track driving (racing). That includes noises, track bumps, wind forces and so on. This is why the wheel speeds are so interesting for henningo. He is working on modern traction control system.
TIP to get wind force:
***********************************************************************
This is a math fitting procedure and it is quite accurate. I am using this procedure to define a wind force and homemade dyno correction factor for go-karts and in future on prototype Radical.
Fw....as wind force [N]
A......front surface area [m^2]
Cx....something like drag coefficient [/]
V......speed in [m/s]
ra.....density of air [1,3 kg/m^3]
(1) Fw = A*Cx*V^2*ra/2
As A and Cx are very hard to define it is best to put them both in constant....
C1 = A*Cx [m^2]
(2) Fw = C1*V^2*ra/2
As the engine power diagram is known (kW/RPM) (you should also get it for LFS car) it is possible to determine the force that the car has on the drive wheels.
P…..engine power [kW]
M….engine torque [Nm]
Fe…force of engine on drive wheels [N]
w….engines speed [rad/s] (not RPMs) w = 2*pi*n
i…...transmission [i] including driving gear, primary transmission, differential….
r…..dynamic radius of driving wheels [m]
(3) P = M*w
(4) M = P/w
(5) Fe = P/(w*r)*i
Now that the forces Fe and Fw are on the same level it is possible to write balance equation.
a……acceleration of the car [m/s]
m….mass of the car [kg]
(6) 0 = Fe-Fw–a*m
(7) a = (Fe-Fw)/m
Now it is able to compare cars speed form telemetry (on car or LFS RAF file) and mathematically determined one.
V…. speed of car [m/s]
Vo.. staring speed [m/s]
t….. elapsed time [s]ž
(8) V = Vo+a*t
Compiling equations (2), (5), (7) and (8) results mathematical model for fitting wind force constant C1 (9)
(9) V = Vo+(P/(w*r)*i-C1*V^2*ra/2)/m
Using either hand editing C1 and inspecting graph plot fitting or using one of mathematical fitting methods that are included in LIBs should be just a programming routine from now on.
***********************************************************************
I should thank to all of you for hi-level discussion and superb help on the LFS forum.
I prefer LFS as my shelter from ended racing driver career!!!!
Last edited by GrEgce, .
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