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Discussion Starter · #1 · (Edited)
Hi LT, my name is Michael Spenard and I'm an electronics engineer that's developed a system for monitoring tire temps in my Lotus Exige. I've produce a few of these kits for others and I'm now looking to offer them to the public.

Here are the features of the kit:

  • Four IR sensors
  • Narrow 10deg sensor field of view for sampling tire sections
  • Large 1 1/12 by 2 1/2 inch display
  • Weather resistant; sensors can get wet without being ruined.
  • Removable lens cap if they need cleaning or replacement
  • Extra protective lenses
  • Does both fahrenheit and celsius
  • You can adjust the emissivity of each sensor (different materials reflect light at differing rates)
  • Quality harnesses
  • DC supply is designed for difficult automotive environments with large current dumps and voltage spikes

The installation is straight forward. You drill a small hole in the wheel arch for the sensor to poke through. Top center is best to account for changes in tire angle.

Four harnesses are included (two 8 footers and two 6 footers) and I can fabricate a custom harness at no extra charge.

I'm working on a nice bracket for mounting in the Elige cubby area. It'll be available soon. Anyone that purchases these will get sent one at no extra charge when they are ready.

If anyone is interested just send me a PM.
 

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Yes, us racers need to be able measure the outside shoulder, inside shoulder and middle of the tread for a total of 12 sensors...
 

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Discussion Starter · #4 · (Edited)
Right, I'm working on an upgrade kit that allows you to track camber loading through such an inference with 3 sensors per tire. A 12 sensor kit will be >$1k however.

So, for now, I've released this kit that is more entry-level, allowing one to track if your tire operating temperature is up, and sub $1k (my first goal being to provide an economical kit with quality parts).

Thanks for the feedback.
 

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Discussion Starter · #5 ·
What do you guys think of sensors that output a 0-5v PWM signal?

This could then by picked up by a data-logger. Only downside is you would need a cable for each sensor. Whereas, with my current setup 3 sensors could share the harness to each corner. Although, I could perhaps squeeze the copper needed for 3 PMW sensors into one single loom.

Another option is I keep the sensors on the current bus technology, and output a PWM from the display unit for use by a data-logger.

I really want to provide the community with something useful that can provide us with empirical data. We all know how much pure opinion and supposition is worth and how much stock (or should I say mutual funds?) LT tends to put on it.
 

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My friend race-car mechanic told me you need a pyrometer, not IR which measures only the surface.
 

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Discussion Starter · #8 · (Edited)
My friend race-car mechanic told me you need a pyrometer, not IR which measures only the surface.
Well, first, core tire temp can be inferred from the surface temp if you know the thermal gradient. Second, the surface of tire is what makes contact with the tarmac and is, of a course, what matters most. Probes are useful because by the time you get the car stopped the surface temp has cooled down and you need to penetrate to get a reading of any use. IR can provide real time in session data which avoids this limitation. For instance, you'll never know the camber load at a specific turn with a probe. Moreover, it's the relative difference between outer, center and inner contact patches that gives you an idea of the camber load (if this is what you are after).

Check out http://www.texense.com sensors for high end professional teams ($500 a sensor). Pros have been using IR for many years. My goal for the Lotus community is to provide a more economical and turn key solution than what Texense offers.

That said, the usefulness of the data really depends on what you are trying to do. I don't want to give anyone the idea that such a kit does not have limitations. It's not Nikasil. But if you want to simply know if your tires are up to operating temp before pushing your vehicle hard, or if you want to know the real world impact of your camber adjustments, then such data can (and I wont say always) be very useful.
 

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The good drivers can probably have their heads down looking at a gauge and memorising the numbers.
But I am not that good.

Being able to log the data would be of interest to me.
I am assuming that there is some voltage to temp table???
or that the measurements can be done in analogue, or the data sent out on CAN?
 

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Discussion Starter · #10 ·
The good drivers can probably have their heads down looking at a gauge and memorising the numbers.
But I am not that good.

Being able to log the data would be of interest to me.
I am assuming that there is some voltage to temp table???
or that the measurements can be done in analogue, or the data sent out on CAN?
Right. There would be a table for the width of the PWM signal to temp (well, a base floating point integer, that would then get multiplied by a factor for C or another factor for F). I think :panic: That's what happens with the current bus architecture anyhow.

At some point I could do CAN out of the sensor itself. But I'd need to put a uC on each sensor. Doing such, would likely make the sensor package to big. Therefore, most likely, CAN would have to be pulled off the display board. Or if you don't want a display a "brain box."

Thanks for the feedback. It's been helpful in giving me an idea of what sort of development schedule I should continue to follow.
 

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Yup, not sure how many log data...
I think not many, but for me it is better.
So CAN could be useful if each sensor had an address.

The base system would also be useful - with single sensor... and logabble.
 

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I can envision 4 sensors with a display.
And I can envision 12 sensors being logged.
I cannot envision 12 sensors being displayed.
 

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I can envision 4 sensors with a display.
And I can envision 12 sensors being logged.
I cannot envision 12 sensors being displayed.
Yah, probably a case of TMI, but could be very interesting to log all twelve temps and see if there is a correlation with throttle position (torque to drive wheels), steering angle, and segment lap time. I can see this being a significant driving improvement tool in addition to a setup evaluation tool.
 

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Discussion Starter · #15 ·
12 temp readings on the display would definitely be to much info. However, what if I had a little ----|---- type graphic for each corner that showed what the temperature bias was. For instance, 80 80 80deg would be ----|---- and 70 80 90 would be -----|---

That would make the display of some use in addition to the logging of those 12 points.
 

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This can easily be taken to the n-th degree, but at the end of the day, what is going to be the most effective data for the guy at the race track. There is no way I could afford to take 2-4 seconds mid turn to look at a display and attempt to comprehend the gradient temp on even one tire of the car. The 4 sensor kit with live display would be very good at providing general knowledge of tire temp and how it changes with warm-up lap, outside temp, tire pressure, track type, etc.

I think you are going about this well, by supplying a 4 sensor and 12 sensor kit. The 12 sensor kit could only be fully utilized with data logging. So a turn can be studied in detail.

I always liked how Forza had a HUD with colored tire temps. But I've screwed up a turn more than once because of looking at them, good thing that game has a rewind button.


 

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Agree , 12 sensors is to much info to read , but 4 would be helpful to view Eg race warm up , practise , testing .
Could you have the best of both worlds .. 12 sensors reporting to Data logger for post race / practise review and 4 sensors reporting to a display in the car ?

Good work and thanks on developing this project.
 

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12 sensors at once too much to read. BUT 4 center sensors, FL 3, FR 3, RR 3 and LR 3 back to 4 centers at the press of a button would be excellent, with a second button to freeze the reading (until you got parked back in the grid/paddock or wherever your flavor of racing has to go to at walking speed, taking forever and a day) would be excellent. More than 2 buttons... not likely to be a good idea. One red button, one yellow button both at least the size of a keyboard key and separated by twice as much space so there's some hope of hitting the right one and not missing. All of the above not changing the logging at all. (maybe a 3 second button press to start/stop logging?)

And if you can make that plus the 12 sensor for about half the price you mentioned we'll all be happy (well... maybe all of us but you :) ).

Even though I'm not logging anything now, logging will come in the future so that's definitely a plus in my book.
 

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I really like this idea idea, and hope you continue to develop. To explain my rotating display a bit better it would be like this:

Code:
LF  |  RF
106 | 108
---------
LR  |  RR
110 |  112 


(press)


 LF |  R
    |  108
---------
 L  |  C
104 | 106 


(press)


 L  |  RF
106 |  
---------
 C  |  R
108 | 109


(press)


  C |  R 
112 | 113   
---------
L   |   RR
111 | 


(press)


L   |  C
109 | 110
---------
LR  |  R
    | 112


(press)


LF  |  RF
106 | 108
---------
LR  |  RR
110 |  112
 
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