Tech DIY - Lateral Gs: Actual measurement, Accelerometers and GPS.

[Laptimer]

no brooooooooooooo!!! dun gooooooo!! dun raaaannnnn!!



from you i still wan to unnerstan

1. how to know where de nose of de car is with onli accelermeter

2. wich one more impt to know:: lateral g wrt chassis or lateral g wrt to chassis path

3. gps drift is how much in 4 secon and how much in 60 secon show me your test den i show you mine!!

4. how to use accelemeter to win de tta

5. why cannot get our own groundstation for rtk gps?????

---------- Post added at 12:41 AM ---------- 6 hour anti-bump limit - Previous post was at 12:39 AM ----------

com bak n teach seng!! teach everi one on forum!!! teach the worlD!!!!!!!
if you teach seng he will be your best baddy for life!!!!

 

[shiroitenshi]

If you studied about accelerometers as much as you've read on gps, i'm sure all those questions can be answered by you yourself. I'm not the designer of the accelerometer, nor did i invent the measurement formula for lateral g on the skidpad. If you think they are wrong, then take it up with them, not me. I studied about them because I use them, and I find them useful in letting me know if I have good grip or not.

But simple answer to your questions.

1) get rsm with the g sensor or any 2 axis accelerometer, turn it left and right, front and back, side to side, and you have your answer.

2) see above, but limit movement to side by side.

3)Drift? Why should I be the one to prove it's accuracy? Can you prove there is no drift in readings when there is sudden gps interference due to lack of 'line of sight' to the satellites? Can you drive into a tunnel (extreme example) and still believe you have accurate gps readings? You're the gps expert. I already stated why groundstation required, the reading is constantly off when the signal is bounced of objects. It's not like it changes every milisec. Then again, you would have known this if you own a gps, so why are you so insistent that the gps is constantly accurate? It's a line of sight system.

3) key to winning tta is a good car and driver. Good driver need good car to win. The crew use all information they can, including from g sensors to make the car better for the driver. If you give me a good car, i'd still lose in the tta because i'm a lousy driver and don't know how to use the car. What makes you think just having a g sensor automatically gives you an advantage? Can you get any advantage from it if you don't know how to use the technology? Using g sensor, you can detect at which point the car slides sideways, mentioned above earlier.

4) you already know why, it's too much trouble to do. Google functions of gps ground stations and why australia had it installed to improve accuracy. If it's so good to track cars with, why not airplanes? 2cm CEP you mentioned shouldn't matter since airplanes is so big right?

Whatever bro, you are more interested in trolling rather than discussing this courteously, so i'm saying goodbye, because while it was interesting when you mentioned high gps accuracy, it has gotten stale at this point. Feel free to continue alone if you like, i'd reply only if someone is asking how to use their accelerometer, since I can at least help with their installation and logging rather than calling them stupid and not learning anything new.

 

[Laptimer]

But simple answer to your questions.

1) get rsm with the g sensor or any 2 axis accelerometer, turn it left and right, front and back, side to side, and you have your answer.

no no brooo not so easy to run is not so easy
you smart you know not so easy but you dun trick others beliving so easy ok??

you drive your car with rsm wadever 2 axis accelemrter through turn
acceletermeter say got 1.0 g lateral
but is it really 1.0 g??? how you know without chassis slip angle???
even if you got 0 roll n accelrometer say 1.0 g you STILL DUNNO YOUR REAL latarel g wrt de path hahahha

you keep run away from this question
run run run
act like easy when not!!
CAN SAY YOU ARE ONLY ESTIMATION LATERAL G HAHAHHAHA
ALL IS ESTIMATION!!! UNTIL YOU HAVE DE CORREC SENSOR N YOU KNOW HOW TO USING!!!

i use my boss computer draw for you ok???
you can solve mean you are world best acceletmer user!!!!!!
firs one show car in turn
chassis slip 0 deg for example oni (but actuali real life will always have some chassis slip oni how big)
from the accelrometer in such a car can see lateral g wrt path n to chassis (red longtitudnal green lateral)
right side same turn but now chassis got some slip angle but path exact same
now to get true lateral wrt path which is more imp for true lateral g holding since every car will have chassis slip angle
oni by knowing the chassis slip angle can we use de trigo matematic to find the orang arrow which is de true lateral g wrt path
you can put your own number into there n try solve but without de slip angle you wun able !!!!

2) see above, but limit movement to side by side.

no lah!! veri sad you dunno all these bro!! liddat how you teach seng??? seng wan to learn from you tot you master expert
end up maybe you oni the [ass bird] not de [expert]!!!

3)Drift? Why should I be the one to prove it's accuracy?

cos you say gps not accurat
cos you say the lateral g is onli estimate

Can you prove there is no drift in readings when there is sudden gps interference due to lack of 'line of sight' to the satellites? Can you drive into a tunnel (extreme example) and still believe you have accurate gps readings?

wah lan eh! you realli tok cok ok!! sepang got de tunnel or not? got de tall building near by? you got test gps b4 anot??? got prob with signal meh??? dun tok cok lah here not monaco tunnel dunno wat ting

i tell you alrdy i got test liao kenji got test kazama got test you tink we stupid izzit? oni you smart? oni you know? you king liao loh!!

4) you already know why, it's too much trouble to do.

you like the frog in de well never see outside before ting you veri smart other all stupid

GET your own rtk basestation loh!!!!! why cannot? dun say what australia have to buy then malaysia dun have all these rubbish lah!! dun anyhow tok!! you keep anyhow tok! look back see wat you say about roll and chassis and why put acceletmer middle of chassis cos middle of chassis less roll? W T F ffffff BROOOO?????? dunno dun say! simple!!!!

oklah seng yahoo search for you ok
nah VBOX - Non Contact Speed & Distance Measurement using GPS


but even with 3m cep and no base station all these impt tat everi one knows dat the gps lateral is very accurat !! cos even wit de 3m cep 150 secon gap come back same place is still within few cm oni cos gps drift happen veri slow oni!!!!! oso the lateral is calculate real time reference oni 0.05 - 0.2 secon b4 current point in time!!!! no even secons not even minutes SO DE GPS DRIFT NO EFFEC ON INSTANTANOUS LATERAL G!!!!

 

[Laptimer]

ok i update drawing make more clear
shiro i wait for your answer ok!!!!!
teach seng teach the world!!!

 

[^pomen_GTR^]

errrr...why chasis slip angle so important in time attack??? :hmmmm:


i tot less slip=faster time????
and more slip=slower time but good drift????

just curious and need explaination...

 

[Laptimer]

errrr...why chasis slip angle so important in time attack??? :hmmmm:


i tot less slip=faster time????
and more slip=slower time but good drift????

just curious and need explaination...

brudder actuali everi car will got slip angle when turning oni ting is how much
some car more some car less depen on many ting like how de tyre is make n the suspension desin n de driver skill n many oder ting
not say always can see big big slip angel
some time can 4degree or 9 or 12
but if dunno dis den poor brudder shirotenshi got no way to know de true lateral g wrt path
he poor ting onli is estimation onli!!!!!!! hahahhahahahahahhahahahahha

---------- Post added at 02:55 PM ---------- 6 hour anti-bump limit - Previous post was at 02:50 PM ----------

de drawing i pos yestday is not say to scale
is oni for de idea and to show what i means
de slip angle is not scale

 

[shiroitenshi]

at least now I know why the readings appeared off in the video... thank you google.
Track TV • View topic - Video Vbox Lite - differences between data & video

ignore mode in full effect :)

---------- Post added at 05:38 PM ---------- 6 hour anti-bump limit - Previous post was at 05:30 PM ----------

The same argument, different country.
Lateral Speed and acceleration from GPS - 10-Tenths Motorsport Forum

---------- Post added at 05:41 PM ---------- 6 hour anti-bump limit - Previous post was at 05:38 PM ----------

Accuracy of accelerometers debate.
Acceleration, gyro, GPS ( - comp.dsp | Computer Group

---------- Post added at 05:46 PM ---------- 6 hour anti-bump limit - Previous post was at 05:41 PM ----------

GPS data quality.
http://www.race-technology.com/upload/Technical assessment of DL2s GPS data quality 6.pdf
This article is interesting because it supports the argument that gps is accurate, but only if GPS is getting good signals from satellite. (corrections from groundstations, etc.) if don't have, the error rate is mentioned there as well.

 

[Laptimer]

hahahahhaha shirotenshi veri poor ting
veri veri poor ting
say ting but he dun unnerstan cannot say why he get these number or why he testing result is these way
but actuali he never even test!!

he cannot answer any of de 6 question
end up he haf to post 4 long tread support my point except some poster inside also made same mistake he make all never test demself all dun unnerstan cep
shiro oso dun unnerstan phasing vs magnitude n oso dun unnderstan gps filter
dun unnerstan roll or slip angle oso

wid no unnerstaning it not supriseing to see tat he cannot answer any of de 6 question n can oni give link tat he dun even unnerstan wat dey say
i oso not surprise tat bcos he cannot answer anyting he wan come soot me say i got no car drive lah got no trophy lah all these ting
when actuali i got car drive
i drive much better than he
and i got win de trophy at tta alrdy

shirotenshi is de stupid liar!!! actuali i see how he say ting oso i dun ting he even drive on track
das why he never test on track
he dunno wat he saying oni!!! be careful of wad he say! even some moderator here oso never careful tink end up belive him!! very dangeros!!

oni know how to yahoo oni
say he no interes
but den sudden got interest but oni when he yahoo new link wich he dun even unnerstan!! hahahhahahha
den when he cannot fine new link will say no interest wan to quit these thing
wah lau dam bad atitude these kin loser atitude wan

---------- Post added at 06:31 PM ---------- 6 hour anti-bump limit - Previous post was at 06:11 PM ----------

i realli veri dun like this shirotenshi
more i see how he change wat he say and everi ting also dun unnerstan but still act act
more i dun like him

see he quote de Track TV • View topic - Video Vbox Lite - differences between data & video writing say he now unnerstan why kenji video g was liddat
but they all is say the filtering for de video overlay all make g a bit lower
but if you check again de old kenji thread this shirotenshi is down there saying de g is too high hahhahahhaha
so wat there to unnerstan? video g lower but you say so high
so wad? real g even higher den wat you tot is alrdy so high? hahhahahahhahah cok lah shiro!!

---------- Post added at 06:39 PM ---------- 6 hour anti-bump limit - Previous post was at 06:31 PM ----------

GPS data quality.
[/COLOR]http://www.race-technology.com/upload/Technical assessment of DL2s GPS data quality 6.pdf
This article is interesting because it supports the argument that gps is accurate, but only if GPS is getting good signals from satellite. (corrections from groundstations, etc.) if don't have, the error rate is mentioned there as well.

HELO!!! read properli ok!!!

"Differential GPS corrections only improve positional errors; they have no direct or
significant effect on speed or distance."


n what is use for deriving acceleration? distance n time!!
hahhahah
dis is wad i mean when i say you dun unnerstand cep and relative vs absolute position n gps drift n wich is involve in get de realtime lateral g!!!
wit or without de basestation de lateralg is accurat!! hahahhahah
i say so many time you still dun unnderstan
poor ting lah you

 

[Zzeenn]

wtf is happening here i had a headache just by reading your comments Laptimer.
by all means, share with us all your ideas, why do you think you are right. i think its a good discussion. but please re-read back your post before posting them. you dont need to be super sarcastic and annoying to prove your points. calm down man

 

[Laptimer]

ok bro sorri sorri i try to come down
is oni for shirotenshi actuali
ok i breathing slowli slowli now

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shirotenshi pls give us de answer so we know de true lateral g wrt path from accelerometer oni ok!! remember tat you oni know de acceleraton in the fix green n red direction n noting else
hahahahahah
oso remember tat the slip angle can be change while turning is not fix

 

[TitanRev]

Yeah, like Zzenm said.

Debate is good but doing it in a good manner is even better. No one here is stupid or more superior than anyone. Everyone here is just to share their know how, that's what make a forum healthy. Don't have to call people stupid or what.

We are here to make friends not enemy.

 

[shiroitenshi]

I do remember a certain someone posting in the ken ji's thread saying I was wrong, because "it's all very accurate"?

I still think it reads high regardless. There was a vice-versa phrasing there unmentioned. I think the forummers that went and read the thread can see the debate for themselves and make their conclusion.

Don't listen to me or laptimer.if you're doubtful about the accuracy. All information is out there, and you guys can read them and do practical tests and see for yourself.

For me, i'd rather attend to other things, because I find this debate officially over.

The gps data quality pdf already has all information about how accurate gps is (even if it's 100hz) and why for certain readings gps better, and for some readings like lateral g an accelerometer is better.

Also, accelerometers been used in track racing for a long time, and there's even general guidelines to compensate for body roll depending on type of car.

Well, rather than explaining more about slip angle, I invite forummers to read about it. It determines cornering forces, so it's good to know so you can see what kind of g's you can expect when your car turns, but it's not an element to calculate/measure lateral g per se.

---------- Post added at 12:05 PM ---------- 6 hour anti-bump limit - Previous post was at 11:26 AM ----------

will do the picture answer later on the computer. With phone very difficult. Now this, is interesting.

 

[Laptimer]

I still think it reads high regardless.

you tot
i think
but who confirm???
where is de confirm??
I think it reads low
actuali i KNOW it read low cos i ran the test b4 both accel n gps same time and compare many time
what test you have done????

you dunno that the reason why gps phasing and magnitude is low or off is bcos of filtering in sofware n inherent the lower de data rate of de system like 10 vs 100hz

you oso dunno that the phasing is simple fix in sofware and oni bcome problem in veri fast race car
all these time attac car all no problem one
n can phase in sofware

de thread link before oso confirm is low hahahhahahha

There was a vice-versa phrasing there unmentioned. I think the forummers that went and read the thread can see the debate for themselves and make their conclusion.

why? cos you tot?
i tink??
n nobodi confim????
dun tink pple here is all gongong one cannot see your rubbish ok
got some pple here also quiet quiet never say anyting
oni i say cos now yr end holiday no racing seng quite free ok

Don't listen to me or laptimer.if you're doubtful about the accuracy. All information is out there, and you guys can read them and do practical tests and see for yourself.

yes do de tes! go track and do de test!! hahahahhahah

For me, i'd rather attend to other things, because I find this debate officially over.

is not over!!
is you run run oni
say soooooooooo many wrong ting
cannot proven
den you run
try yahoo den oso cannot work
den run agaaaaaiin!!!!!

The gps data quality pdf already has all information about how accurate gps is (even if it's 100hz) and why for certain readings gps better, and for some readings like lateral g an accelerometer is better.

yes! n pple have to see wat kind car is using!!
is formula car?? very fast ? very twitch?
or heavy time attack car 20 secon slower??
hhahahhahhahhah

Also, accelerometers been used in track racing for a long time, and there's even general guidelines to compensate for body roll depending on type of car.

long time b4 de gps technology get so good as now hahahha

HELO! shiroshiro! de road cambre and de roll how to compensate accuratly for both without oder sensor to tell you sprung mass orientation????
how to compensate for de slip angle at de same time as de roll and de camber???

hahhaha i give you answe ok!!
ANSWER IS, YOU CANNOT!! IS BECOMES ESTIMATION IF YOU DUN HAVE DE ODER SENSOR!!!!

Well, rather than explaining more about slip angle, I invite forummers to read about it. It determines cornering forces, so it's good to know so you can see what kind of g's you can expect when your car turns, but it's not an element to calculate/measure lateral g per sep

well it is can see dat shiro OSO DUNNNO about slip angle
i invite forummmers to see dis
he say is not element to measure lateral g
BUT IT IS!!! hahhahhahah

is why he cannot answer the question i ask him hahahhahah
he keep ranning
keep say later later
oni can yahoo n hoping to fine answer
but he wun fine cos dis one is come from ah seng head!! not yahoo!!!
n is wat shiro cannot answer!!

---------- Post added at 06:49 PM ---------- 6 hour anti-bump limit - Previous post was at 05:07 PM ----------

ok lah make simple question for de expert shirotenshi
see if he can answer hahahhaha
ok i open de dictionary and english textbook try to saying clearly de question
hahahah no actuali i ask my cousin to write for me
dis one not on yahoo ok!!!!


A car is negotiating a turn. The car has only a 3 axis accelerometer installed.
At time = 2.0 sec, right in the middle of the turn, the 3 axis accelerometer shows the following:
longitudinal acceleration is +0.12 G
lateral acceleration is +0.83 G
vertical acceleration is -0.04 G

Chassis slip angle, sprung mass roll, unsprung mass roll, road gradient and camber, are all unknown due to lack of other sensors.

What is the true lateral acceleration of the car at time = 2.0 sec ?

 

[shiroitenshi]

Pomen_GTR, chassis slip angle isn't amount of slipping the car does.

It happens because tires on car only can steer at the front, the rears are static so they track the turn differently than the front. so they have an instant center of rotation. and that's what chassis slip angle means. Accelerometers already have chassis slip angle already accounted for because the chassis is the y-axis on the accelerometer. That's why the directional mounting on accelerometers are important and stressed on in any 2 axis accelerometers you buy. You can confirm this if you asked the race crew/racers in or outside malaysia. That's why accelerometers are still used until today for most motorsports teams, even after GPS is introduced.

Accelerometers used in racing long time already before GPS, read about it's applications and uses. I also mentioned it's affected by roll, I don't claim it to be 100% accurate. It can't do everything, but it does one thing well, and that is measure G-force.

Can GPS know road gradient and camber? Not unless it has a gyro, which is another type of sensor, much like the accelerometer. GPS alone can't do that either. Can GPS measure lateral g? not exactly, which is why most higher end GPS units include accelerometers or IMUs in their high end systems. I wonder why is that? If GPS is accurate enough, why add an accelerometer in their systems? Isn't that strange?

For chassis sprung and unsprung mass roll, people use the more accurate suspension travel sensor rather than accelerometers or the gyro. Like this one
http://motorsportsinnovations.com/wb_Travel.htm for the Auxbox.
I'm using the five channel Auxbox, so I don't have enough ports to use this, need more channels, but I wouldn't buy it suspension tuning is something I'm not concerned with, as I don't change suspension spring rates nor do I do it often enough, only tires, so my lateral grip is my concern when I change tires. If after changing tires, I can get higher laterals, then obviously the grip is better since I didn't change the suspension.

 

[Laptimer]

A car is negotiating a turn. The car has only a 3 axis accelerometer installed.
At time = 2.0 sec, right in the middle of the turn, the 3 axis accelerometer shows the following:
longitudinal acceleration is +0.12 G
lateral acceleration is +0.83 G
vertical acceleration is -0.04 G

Chassis slip angle, sprung mass roll, unsprung mass roll, road gradient and camber, are all unknown due to lack of other sensors.

What is the true lateral acceleration of the car at time = 2.0 sec ?

come on bro!! pls help mi n help de forum n help all de time attack team n all de race team all ard the world!! pls draw de picture sho us how you do it!!!! pls brooooo!! no reply to de question??? o my godzzzzz!!! you mus be estimateion everyting oni!!!

actuali you know hor the tta i go see all de car
you know got 100+++++ car
but you know how many is logging accelermeter? ONLY 2!!! n they no where near de top!!!
you know how many car is using gps? EASILY 10!!! n many of they are top 20!!!!!
but these 10 all dunno what they do!!! if they follow shirotenshi n use de acceleratmer den they all surely can go f1 oredi!!!!haiiiiiizzz why dey never use their head ah!!!!