Wheel Slip & Ground Sensors

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Post Sat Feb 18, 2012 12:44 am

bhallg2k wrote:You might be able to find some information here ( http://www.optimess.cn/?lan=1 ). That's the company who makes the sensors.


I was there, but everything seems mounted outside the wheels. This F1 pod must just be the laser with other instruments, accelerometer,etc., actually in the hubs and/or wheels.

Brian
hardingfv32
 
Joined: 3 Apr 2011

Post Sat Feb 18, 2012 12:49 am

Somewhere on this site - god knows where, though - there's a picture of an Optimess control box mounted on the front bulkhead, underneath the master cylinders, of some car. If you can find it, you might be able to get a model number and be able to find the specifics you seek.

Or you can ask JerseyTom.
bhall
 
Joined: 28 Feb 2006

Post Sun Feb 19, 2012 10:21 am

How they reveal the wheel-slip from chassis movement relative to the ground?
Initially i thought it measures wheel slip with centripetal acceleration (accelerometer) and steering angle,and then it is possibile to detect wheel slip.
Correct me if i am wrong.

hardingfv32 wrote:
bhallg2k wrote:You'll see them on most cars in testing and on Fridays during race weekends.


Is a laser measuring the chassis movement relative to the ground?

Brian
Squall
 
Joined: 17 Feb 2012

Post Sun Feb 19, 2012 3:18 pm

Squall wrote:How they reveal the wheel-slip from chassis movement relative to the ground?
Initially i thought it measures wheel slip with centripetal acceleration (accelerometer) and steering angle,and then it is possibile to detect wheel slip.
Correct me if i am wrong.

hardingfv32 wrote:
bhallg2k wrote:You'll see them on most cars in testing and on Fridays during race weekends.


Is a laser measuring the chassis movement relative to the ground?

Brian

movement across the ground combined with steering angle data gives you perfect slip angle info
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Pierce89
 
Joined: 21 Oct 2009

Post Sun Feb 19, 2012 3:57 pm

Pierce89 wrote:movement across the ground combined with steering angle data gives you perfect slip angle info

So, the laser instantly traces the trajectory of the car on the track?
But i have no idea how do this
Is possible that they use this type of laser?
http://en.wikipedia.org/wiki/Laser_accelerometer
Last edited by Squall on Sun Feb 19, 2012 4:01 pm, edited 1 time in total.
Squall
 
Joined: 17 Feb 2012

Post Sun Feb 19, 2012 4:00 pm

Does it work the same way an optical mouse does?
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hollus
 
Joined: 29 Mar 2009
Location: Copenhagen, Denmark

Post Sun Feb 19, 2012 4:02 pm

Pierce89 wrote:movement across the ground combined with steering angle data gives you perfect slip angle info


Well, not quite. But close.

In any event, for those curious about optical sensors... feel free to read up on them.
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Jersey Tom
 
Joined: 29 May 2006
Location: Huntersville, NC

Post Sun Feb 19, 2012 5:00 pm

Jersey Tom wrote:
Pierce89 wrote:movement across the ground combined with steering angle data gives you perfect slip angle info


Well, not quite. But close.

In any event, for those curious about optical sensors... feel free to read up on them.


Very interesting, thank you!
Do you know how (the physical principle) a laser can measure speed?
Squall
 
Joined: 17 Feb 2012

Post Sun Feb 19, 2012 5:15 pm

I would think it can sort of track how much it has moved - then divide that by time. I don't see how a laser could measure speed per se - except if you're talking of something like a speed gun
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raymondu999
 
Joined: 4 Feb 2010

Post Sun Feb 19, 2012 6:54 pm

You can also use lasers for non-intrusive airflow measurement, ie a virtual pitot tube but much more advanced. Wind turbines and FADEC flight systems (fly by wire) as well as drones use them.
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Gridlock
 
Joined: 27 Jan 2012

Post Sun Feb 19, 2012 7:13 pm

Squall wrote:Very interesting, thank you!
Do you know how (the physical principle) a laser can measure speed?


They do not use lasers. It is an optical velocity sensor.
Grip is a four letter word.

2 is the new #1.
Jersey Tom
 
Joined: 29 May 2006
Location: Huntersville, NC

Post Sun Feb 19, 2012 9:51 pm

Squall wrote:
Jersey Tom wrote:
Pierce89 wrote:movement across the ground combined with steering angle data gives you perfect slip angle info


Well, not quite. But close.

In any event, for those curious about optical sensors... feel free to read up on them.


Very interesting, thank you!
Do you know how (the physical principle) a laser can measure speed?

Pitot Tube is used for measuring speed in F1.
A laser can measure speed with two different methods:
1) The instrument shoot a "ray" to an object and it analyzes the frequency of the ray that "returns" to the instrument. It uses Doppler Effect: the frequency of the ray that returns changes depending of the speed of the object.
2) The instrument measures how long a ray shot to an object does take to "return" to the instrument. It uses the kinematics formula of uniform motion: d=c*t
c= speed of light
t= time for the "returning" of the ray
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italian
 
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Location: Italy

Post Sun Feb 19, 2012 10:12 pm

italian wrote:A laser can measure speed with two different methods:
1) The instrument shoot a "ray" to an object and it analyzes the frequency of the ray that "returns" to the instrument. It uses Doppler Effect: the frequency of the ray that returns changes depending of the speed of the object.
2) The instrument measures how long a ray shot to an object does take to "return" to the instrument. It uses the kinematics formula of uniform motion: d=c*t
c= speed of light
t= time for the "returning" of the ray

Where would the ray shoot? If it were measuring time to return that would probably be a ride height sensor more than anything.

If you were to create a "speed gun" using doppler; where would you shoot? You can't shoot front/rear/sides because the walls etc would change.
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raymondu999
 
Joined: 4 Feb 2010

Post Sun Feb 19, 2012 10:21 pm

Maybe I am wrong? :oops: From what I know, lasers measure the SPEED of an object with these methods. If I've made a mistake, excuse me guys, please.
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italian
 
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Location: Italy

Post Sun Feb 19, 2012 10:25 pm

No no; the concept is sound. The doppler effect you mentioned is how speedguns work.

I just don't think this is what's happening in this example.
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raymondu999
 
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