Landracing Forum
Tech Information => Technical Discussion => Topic started by: donpearsall on April 12, 2010, 06:33:03 PM
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Does there now exist a simple, inexpensive aftermarket wheel slip indicator (I know, I know, it's your rear end)? What I am envisioning is something like LED lights that indicate when your front and rear wheels are a certain % out of sync. This is not traction control because it does not control anything. Internet searching reveals that it is on some OEM vehicles but nothing about aftermarket devices. Anything?
Thanks
Don
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Yes its called a tachometer!...... better yet, get traction controll
Kent
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Well all I know is this weekend at Maxton I did not need an instrument to indicate my wheel spin,, it was evident to me and anyone from the start to the quarter mile marker,,, :cheers: :cheers:
"It was not a 1/4 mile Burn Out" it was just an extreme loss of adhesion !!!
Charles
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Rick Y. used to run front and rear wheel speeds with bicycle speedos. cheap and fairly accurate when calibrated correctly.
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You have two free ones, one on the right the other on the left. If you want to keep them working good use ear plugs. :cheers:
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Don, please post any info you find out about this. It does not appear to be impossible.
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The factory types compare the electrical signal generated by the wheel speed sensors which are nothing more than low voltage generators. most of us run different size tires front to rear if the rear generates more it would be spinning.
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It wouldn’t be that hard to build one. You could use two wheel speed sensors and a CAN interface. Also your coding would need to have some values for acceptable wheel slip so you wouldn’t get a false reading. But if your going to all this trouble might as well add some more functions and at that point it will be faster to use an off the shelf data logger. Tony
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I understand the Al Teague's liner had such a device. It worked thru a row small lights, green when it had no slip and a line of ambers which showed how far he was off, I heard it had come from Banks and I'm sure it was used with a data aquisition system. He controlled the slip with his right foot....JD
PS: Don't take this to the bank, I just heard about it.
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Unh, there's an expensive way to do it -- with a data logger. For instance, our MoTeC has inputs where we send information from front and rear wheel speed sensors. We calibrate the unit to account for the difference in wheel circumference - and then we teach the MoTeC to give us whatever output signals we want. In the present case we have programmed it to turn on a bright yellow light, labeled "Wheel Spin" when the rear speed exceeds the front speed by 7%. Everything is programmable.
But the MoTeC ain't cheap, and if all you're going to do is wheel slip indicating -- you can do it lots of other ways.
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Brandon and I were thinking of building one like Teague's.
Maybe if we built a batch of them we could all share in development cost?
How many would be interested? Might be a fun group project.
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I use a MoTec system and it works great. have a light that tells he when i get to a preset % slip. will be activating the traction control piece this year. because the car is all wheel drive, have had to adapt a GPS system to input the car velocity. Commercial GPS generally is not sensitive or responsive enough to provide input. i use a system made in the UK that was developed for just that purpose. as stated above, it is somewhat expensive, but the MoTec offers a ton of options for data logging and tuning. i originally bought the MoTec because of the complexity associated with running compressed natural gas as the fuel. found that it had a lot of additional features, some useful, some just cool. pm me if you would like more info.
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Don, I have wheel speed discs that bolt on the front and rear 'Busa wheels if you think that may help you. EM me if you have questions. Thanks! Scott
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Turk had something simple on the Camaro. He mentioned it was useful in another forum. Maybe Keith will speak up.
Vehicles rarely have the same diameter wheels front and back and would have to compensate somehow. Motec is out-o-my league! . . . but I am sure interested in alternatives.
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It could be done with prox sensors and metallic discs. The number on each wheel would compensate for tire size. The prox could be sent to a simple "black box" that counted each, and output the difference to LED lights. I am not an electronics guy, but we have done similar devices for my day job. One of my kids teachers told me what I needed to get for circuits at Radio Shack (under $30) and he put it together for me. I then made a nice cover. came out nice.
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For what it is worth...
Couple of things to consider (if you haven't already). If the tires are the same size/type (extremely) identical, it is very easy to build one of these devices. Consider that the two wheels you are measuring will change size throughout the run, if the tires are different materials, widths or thicknesses, they will grow at different rates.
In some examples on streamliners, you will have turned aluminum wheels on the front and "traditional" rubber wheels on the drives. The drive wheels will grow at a faster rate and more by percentage than the aluminum wheels will. The different rate and amount of growth will show as wheel slip.
At lower velocities, the rate of growth will be less of an issue than at higher velocities. When designing for the faster velocities, you may need a more sophisticated logic circuit with some tire growth data to be used for making adjustments.
In the extreme example, the 28.5" MT Bonneville tire will grow 15% over static height at 400 mph while an aluminum wheel will grow at a much lower rate. If you do not compensate for the growth rate of the two tires, the faster you go (even with zero slip), your indication will be that wheel slip is occurring.
Even with two traditional wheels, running a Goodyear on the front and a MT on the rear, they will more than likely grow at different rates. It will not be as extreme as the turned aluminum/MT combination, but it will be different. Since you want to keep wheel slip to a small percentage (3-5%), the minor differences in growth rate might wreak havoc on your indications without applying corrections.
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If the rear tires are growing more than the front and the car is a rear wheel drive car, the circumference of the rear tires will be larger and assuming no actual slippage, the tire slip will in fact show as a negative number because the rear tires will turn at a slower rate compared to the fronts. :-o :-o (I think my old teachers used to refer to that as a "run on sentence".) :-D :-D :evil:
Pete
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If the rear tires are growing more than the front and the car is a rear wheel drive car, the circumference of the rear tires will be larger and assuming no actual slippage, the tire slip will in fact show as a negative number because the rear tires will turn at a slower rate compared to the fronts. :-o :-o
Pete
You are very correct sir - negative slip would be indicated. Unless you know the rate of growth/difference at a given speed to compensate for it, your indicator will be useless.
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Front tires will also probably grow.
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I realize that tires grow and such. That is more of a symantic arguement.
I was merely trying to say that for a couple hundred dollars, some good thought, and a clever nerd, it can be easily done. as for the growth, a $100 plc could be used to control the whole thing and formula to correct growth; be it linear, logrythmic, boolean etc. coulde be programmed in.
All that is needed is some mental and physical sweat equity, not a $5000 motec.
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I have been working on a prototype since I started this thread and realized that there was nothing off the shelf and cheap. I should have something to show before Speedweek and if it is functional I will offer it for sale. I will keep you updated.
Don
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Don, I realize that as soon as you start something like this, the "add functionality list" grows almost exponentially. However, please consider a speedometer. Don't laugh. :-D The resolution on a tach is terrible. One or two tick marks on the tach can be as much as 15mph. To be able to distinguish 50 or 100rpm at speed, is impossible. However, for licensing runs you want to be able to guesstimate a few mph. The tool you are designing will have far better resolution than a tach if it is to discriminate small differences between the front and back wheels. You are automatically building in precision that is needed. Why not take advantage and provide not only slip but speed? The Apollo GPS I have used was not useful but maybe newer units are better.
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That's a given! As a programmer, I am all too much aware of "feature creep". Here is the exterior design & LCD layout.
Don
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That's a given! As a programmer, I am all too much aware of "feature creep". Here is the exterior design & LCD layout.
Don
Wow, looks a lot like what I had designed! :-D
Guess I'll have to do the HUD display and integrate it with the other engine indicators just to be different!
http://www.microvision.com/vehicle_displays/head_up_displays.html (http://www.microvision.com/vehicle_displays/head_up_displays.html)
Watch out for the creep, it has cost me $100s of thousands in implementation fees over the years. Programming would be a lot more fun if it weren't for the end users wouldn't it?
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Will it store/log its data?
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Fred, the first version won't, because it is just an indicator, but that is something that will be a feature.
Don
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The LED layout looks perfect for me. :-) Will you have a prototype at SW?
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Our new Buick LaCrosse has a heads-up display and I love it!
Regards, Neil
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I wonder if Don Pearsoll or others have come up with a lil electronic gadget which displays progressive wheel slip in the 4 years since this thread was posted??.
In Aug 2014 our lakester will have a Racepak logging system and we'll log wheel speed and GPS speed; the Racepak math function will generate %wheel slip which will be logged.
All interesting, but as several of you have indicated, it sure would be nice to have line of LED's which indicate progressive % wheel slip.
With our modest NA power we don't really need a slip indicator in any gear but 1st, but i'm determined to get one made if i can't find one off the shelf :-D
Karl
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I wonder if Don Pearsoll or others have come up with a lil electronic gadget which displays progressive wheel slip in the 4 years since this thread was posted??.
In Aug 2014 our lakester will have a Racepak logging system and we'll log wheel speed and GPS speed; the Racepak math function will generate %wheel slip which will be logged.
All interesting, but as several of you have indicated, it sure would be nice to have line of LED's which indicate progressive % wheel slip.
With our modest NA power we don't really need a slip indicator in any gear but 1st, but i'm determined to get one made if i can't find one off the shelf :-D
Karl
Megasquirt is quite economical and....
(http://1fatgmc.com/car/car-other-1/MS3-Pro-speed%20sensors-1.jpg)
http://1fatgmc.com/car/car-other-1/MS3-Pro-speed%20sensors-1.jpg (http://1fatgmc.com/car/car-other-1/MS3-Pro-speed%20sensors-1.jpg)
... even if you didn't use it for fuel air you can data log with it and it has traction control available with inputs for a driven and non-driven wheel plus wastegate control when you put a turbo on the engine and lots more,
Sum
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Sumner,
I much appreciate your input, but I'm not looking for closed loop traction control, or an engine management control system. Those are great additions to a vehicle and i've heard many good things about megasquirt. :cheers:
I'm not one of those rocket scientists, i'm just looking for a simple device which displays % slip.
We will be logging % slip, and that signal could trigger one of the 4 warning lights on the Racepak dash.
However i'm thinking a line of progressive LED's could help me anticipate and maybe mitigate a traction problem.
I just want put my right foot to work in 1st and see how hard i can accelerate without letting the slip get too bad. I could probably simply get a 270 degree gauge displaying volts, but i like the idea of a an LED strip.
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I think the basic problem is to get a wheel speed from each rear wheel and a front wheel. Maybe a sensor from an ant-lock brake system could be used to do this. Take the difference between the front wheel speed and each rear wheel and display the difference. This way you can monitor which rear wheel is spinning. If the tire diameters are different front to rear, some scaling would be necessary before taking the difference.
Regards, Neil Tucson, AZ
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Karl, is there a 0-5V output on your Racepak? If you could send your math function of GPS x wheel speed, there are digital gauges out there that can give you a visual indicator for any 0-5V signal. -Dean
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http://www.veisystems.com/ws/v1-series-single-gauges/34-v1-series-universal-voltage-signal-monitor-.html
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I'm not trying to be a smart a$$ but I think before someone would see the lights and decide what to do about it their butt would already be telling them what is going on. I will agree that in 1st you can be looking at stuff like this to some degree but in higher gears the ability starts to go away and things happen a lot quicker.
Neil with a spool or say a Torsen one should only need one driven wheel sensor I'd think.
I realize traction control is still an evil concept to some and might always be, but the writing is on the wall. Cars like Speed Demon have shown if you want to go real fast with big HP numbers traction control and other computer controls like what is possible now with computerized wastegate control is going to be hard to beat
Sum
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Karl, is there a 0-5V output on your Racepak? If you could send your math function of GPS x wheel speed, there are digital gauges out there that can give you a visual indicator for any 0-5V signal. -Dean
Dean,
Racepak sells gauges which can be plugged straight into the system.
1) the 1st question becomes whether math channel output is available to drive a gauge
2) if it is available, then the 2nd question can that signal drive non-Racepak devices
I am pursuing those questions now.
Karl
I like that lil gauge you linked, and it is kind of along the lines I am thinking.
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Sumner,
I have zero car experience and nearly all my LSR bike experience has been on asphalt, so i could easily be WAY off base in looking for a device to display % wheel slip.
Even still, i am determined to get a gauge or a linear strip of LED's (preferably) which tells a glance how traction is trending. I agee with you that a warning light wouldn't help me.
Heck, even a strip of 12 progressively colored LED's might not help me give my right foot sensitivity training.
Karl
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back to the drawing board.
I appears that my Racepak system math channel output is NOT available to drive external devices
My ever helpful Racepak supplier, Greg Kelley, has contacted Donny at Racepak and he is cogitating on this.
(to be continued...)
Karl
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..back to the drawing board.....Karl
OK now I will be a smart a$$ 8-). You connect your throttle linkage to a potentiometer/rheostat that is connected to 12 volts and a 12 volt bulb. The more you lift the brighter the light gets :evil: :evil:,
................... or...............
A non-smart a$$ idea. A second set of your speed sensors connected to the 0-5 volt aguge if they can output a 5 volt signal. I think most speed sensors have a frequency or switched digital output that wouldn't work with the gauge but I guess there are some that have an analog voltage output.
The lights are going to require a more sophisticated circuit.
Good luck,
Sum
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Hall sensor on the drive shaft, hall sensor on a front wheel some minor calculations and one of these would do the trick.
http://www.arduino.cc/ (http://www.arduino.cc/).
These Arduino boards are pretty slick. There are analog, digital, drivers, switches, software, hardware.. everything you could think of available in these little buggers. They aren't expensive and they are fairly easy to use.
Something to consider in measuring wheel slip. If the front and rear wheels grow at different rates, you could actually slip the rear wheels and show that the there is no slip at all. As the rear tires grow, the ratio of ground speed to RPM will change. I would do a little bench testing to see how your tires grow at speed and measure the growth. With that, you can probably supply better data into your function to determine if the wheels are slipping.
For those that don't believe tires grow, I'll include a little video and some data.
This is a 30" M/T Bonneville tire spun to s surface speed of just about 540 MPH. The static height of the tire is 29.2" and the full growth in this video is 34"!
http://youtu.be/CBhiJNbB6KA (http://youtu.be/CBhiJNbB6KA)
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In tuning your slip system, whatever you have, use the coast down data at the end of the run. You will have zero slip at that point and the growth is there. You should be able to then train your system with good base line numbers to work from.
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Hall sensor on the drive shaft, hall sensor on a front wheel some minor calculations and one of these would do the trick.
http://www.arduino.cc/ (http://www.arduino.cc/).
These Arduino boards are pretty slick. There are analog, digital, drivers, switches, software, hardware.. everything you could think of available in these little buggers. They aren't expensive and they are fairly easy to use.
Something to consider in measuring wheel slip. If the front and rear wheels grow at different rates, you could actually slip the rear wheels and show that the there is no slip at all. As the rear tires grow, the ratio of ground speed to RPM will change. I would do a little bench testing to see how your tires grow at speed and measure the growth. With that, you can probably supply better data into your function to determine if the wheels are slipping.
For those that don't believe tires grow, I'll include a little video and some data.
This is a 30" M/T Bonneville tire spun to s surface speed of just about 540 MPH. The static height of the tire is 29.2" and the full growth in this video is 34"!
http://youtu.be/CBhiJNbB6KA (http://youtu.be/CBhiJNbB6KA)
bbarn,
thanks a million for the Arduino link. I had never heard of it. What a concept, make it easy to build electronic lil electronic gizmos". Interesting to know about and possibly I could even do it.
:cheers: :cheers: :cheers: :cheers: :cheers:
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Radio Shack carries Arduino but it will be a few bucks more than getting it from Amazon. You will just need a an UNO not a MEGA. Welcome to the Arduino world!
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I cant see where the Uno reads frequency ? or can the 0-5v inputs be programmed for freq ?
but my understanding of electronics is pretty basic
i was wondering about a frequency comparator of some sort using simple ic's
Update
called a mate thats good with this stuff and he suggested this
http://www.altronics.com.au/index.asp?area=item&id=K6220
http://www.siliconchip.com.au/Issue/2009/November/Twin-Engine+Speed+Match+Indicator+For+Boats
gauge supply could be intercepted for logging , and you could make pickup reading adjustments to dial in tire size differences
He also explained Arduinos , they would work well ,but depends on the level of complexity you want to which system would be the better choice
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I am happy to see that there is still some interest in a Slip Indicator. I originally started this thread and after determining that nothing existed that I could just bolt on, I began prototyping an indicator that may work for me while riding my bike. My name for it was "Slipometer".
The prototype works as designed - BUT when I tried it out at Bonneville I found out that I was paying way too much attention looking where I was going than at the slip indicator. Then on one run my engine blew and I got busy rebuilding the bike and engine and the Slipometer has just been sitting in a box.
Here are a few features:
1. The Slipometer is merely just a counter that keeps track of two inputs - the front wheel and the rear wheel speed.
2. Input is via a stationary hall-effect sensor that counts passes of a rare-earth magnet as the wheel revolves.
3. The indicator has 15 sequenced LEDs that are green, yellow, red. You can program the LEDs to light up at a certain percent of slippage.
4. Display is a 16 x 2 LCD.
5. It has a crude menu system where parameters such as the slippage limit, KPH or MPH, wheel circumference, etc are set.
6. While running, the speed is displayed in MPH or KPH.
7. While running the RPM of each wheel is displayed.
8. At the last minute I added a feature that would close a switch and ground an input wire at a certain % of slip. This was to act as a sort of traction control in conjunction with my Dynatek piggyback ignition. Grounding a particular wire retards the ignition.
It was a fun and educational project. However for racing I don't know if it is practical. In a bike environment you are hunched over, can barely see out of your helmet, the displays are real close and out of focus (for me at least), and there is way too much concentration just to stay on course and upright. Something like this may be better suited to a car environment.
Here are some pics.
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Don,
yr slipometer is a VERY cool little gadget! You must have had fun building it, yup!
I am a (ex)bike guy and I agree when hunched over at speed I can't focus on little displays, just glances at AF maybe.
Yr box is kind of what i thinking about, but all I want is the row of LED's.
Did you have it set up so that all the greens then all the yellow, then all the reds, or was it progresssive one by one?
Karl
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Karl,
The LEDs were progressive, one by one.
The LEDs were set so that the colors lit up depending on the severity of the slipping. For instance by using the menu system you could set the parameters of the green set to be from 1-10% slip. So at 2% slip the first LED would light, then the second at 4%, the third at 6%, etc. Then you could set the parameters of the yellow set to be 11-20%, and the red set to be 21-30%. Etc, etc.
Don
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Karl,
The LEDs were progressive, one by one.
The LEDs were set so that the colors lit up depending on the severity of the slipping. For instance by using the menu system you could set the parameters of the green set to be from 1-10% slip. So at 2% slip the first LED would light, then the second at 4%, the third at 6%, etc. Then you could set the parameters of the yellow set to be 11-20%, and the red set to be 21-30%. Etc, etc.
Don
Don, that is exactly what I am envisioning. Just the progressive lights.
We will be installing a Racepak logging dash which will grab plenty of data, displaying some of it. But like you, i don't really look at the numbers while running unless there is something specific like how AF is in a certail rpm range, say dangerously lean on a shakedown pass.
Is it a complicated task to build (or have built) a box which just has the led's and their controller?
I am checking whether Racepak can output wheel mph and maybe GPS to a gauge, and if to a gauge, why not to your slipometer?
But all that said, i gotta say that i have never driven a racecar on the salt at all, and don't know if the LED strip would be useful at all??? I just find the idea intriguing and want to pursue it unless it is a solid nonstarter.
Your post gives me encouragement, THANKS!
Karl