## Has anyone tried logging shock velocities? Sample rate ok?

TheOtherEric
Posts: 14
Joined: Fri May 19, 2006 5:21 pm

### Has anyone tried logging shock velocities? Sample rate ok?

I've found some cheap ride height sensors and thought I'd give this a shot as a way to tune double-adjustable shocks. However, the DL1 can log at only 100 Hz, which may not be fast enough. Does anyone know if that will work?

osborni
Posts: 497
Joined: Fri Dec 07, 2007 9:08 pm
Location: USA, Michigan
At 80 mph you are going 117 feet per second. So 100 cycles per second gets you a resolution at a little more then 1 foot per travel per reading. Probably mearly OK for suspension. 200Hz would be better.

That depends on the response rate of your sensor. Most industrial laser ride height gauges measure at about 0.05 seconds per cycle. So your sensor is operating at about 20 Hz or a reading every ~6 feet. Probably not good enough.

What sort of sensor?

Anyway, if you, as a driver, can tell the difference between a few clicks of shock setting, then this might help. Most of us mortals can find 5-10 seconds with much more simple analysis of driver (lack of) skill.

TheOtherEric
Posts: 14
Joined: Fri May 19, 2006 5:21 pm
Interesting thoughts, but I don't think forward travel speed has anything to do with it. My engineering skills are rusty, but I figured you'd assume a sinusoidal shock motion of some amplitude A (1-2 inches shock travel?) then take the derivative to get V, and then set V equal to say 5 in/sec (since you don't really need data above that) to calculate frequency then compare the frequency to your 100 hz sample rate.

I'm rusty on the equations like taking the derivative of A=sin(wt)...

I was looking at mid-90s Ford ride height sensors. I'd assume these are just some pots (variable resistors) so sample rate shouldn't be an issue.

osborni
Posts: 497
Joined: Fri Dec 07, 2007 9:08 pm
Location: USA, Michigan
If you are tuning shocks, then you need to know how fast the sensors are reacting to the ground/car relative motion. AT BEST, 100hz lets you tune low speed bump and rebound, not higher frequency high speed bump.

jlucas
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Location: Delaware, OH
Contact:
There is stuff in the works to be able to log more meaningful shock velocities. However I have no control over it so I can't say anything about the timing of it.
Jeremy Lucas
Fast Tech Limited - a Race Technology Dealer

itb242
Posts: 4
Joined: Sun Jul 12, 2009 7:50 am
jlucas wrote:There is stuff in the works to be able to log more meaningful shock velocities. However I have no control over it so I can't say anything about the timing of it.

Jeremy,

Is there an ETA on the increased sampling rates for damper linear pots? Also, will this be a hardware or software upgrade?

David

itb242
Posts: 4
Joined: Sun Jul 12, 2009 7:50 am
osborni wrote:If you are tuning shocks, then you need to know how fast the sensors are reacting to the ground/car relative motion. AT BEST, 100hz lets you tune low speed bump and rebound, not higher frequency high speed bump.

500 Hz or better. It's my only hang up to not buying the DL-1 right now.

David

jlucas
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Joined: Tue Nov 29, 2005 12:45 am
Location: Delaware, OH
Contact:
itb242 wrote:
jlucas wrote:There is stuff in the works to be able to log more meaningful shock velocities. However I have no control over it so I can't say anything about the timing of it.

Jeremy,

Is there an ETA on the increased sampling rates for damper linear pots? Also, will this be a hardware or software upgrade?

David

I can only tell you what I know but none it helps with timing.
1) RT is working on a hardware solution for the future. Whether it will be add on hardware module or a future DL1 revision I don't know but it won't be software because the current board can't go faster.
2) A couple of guys in the US are working their own hardware solution to sample at a higher speed to do the math for shock velocity and then output it via serial to the DL1. I will try to get an update on this item.
Jeremy Lucas
Fast Tech Limited - a Race Technology Dealer

itb242
Posts: 4
Joined: Sun Jul 12, 2009 7:50 am

David

Bikey
Posts: 102
Joined: Fri Apr 29, 2011 6:05 am

Support
We are currently updating the Dl1mk3 firmware and we are aiming to have support for high sample rates available for the start of next racing season.

Kind regards,

RT Support

Bikey
Posts: 102
Joined: Fri Apr 29, 2011 6:05 am

Support
Unfortunately not - only the DL1mk3

924RACR
Posts: 113
Joined: Tue Jul 13, 2010 5:34 pm
Location: Royal Oak, MI
Contact:
Very cool, please keep on this project! It will likely be the justification for me to move up to a DL1Mk3, maybe a Dash 4 while I'm at it...

Support
yes - The DL1mk3 is based on a very powerful 32bit DSP, so we've got many idea on what functions to add on to it in the future... it's a very clever little box!!

support