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Geez chassis datalogging is running! My first plot!

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Geez chassis datalogging is running! My first plot!

Old 01-14-04, 12:54 PM
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Smile Geez! chassis datalogging is running! My first plot!

This is what you get if you leave my house; I did this on the way to work this morning. The run starts from a stop at the far left with the car at a stop sign. Immediately a right turn is made and accelerate up the street, through an ess and then stop at a stoplight The total g's plotted aren't that high but the street was wet so I was using all the tires had, therefore my "usage" on Geez rates high.

At the top left is the friction circle. I accidently cropped it off but the cursor on the friction circle represents the point on the map where the white bullseye is. The gauges on the map represent parameters present at the bullseye as well. It shows me in a slight left turn, slowly accelerating while using 95% of the available grip 27.2 seconds from the beginning of the run. The strip charts on the left show lateral g's, accel g's and total usage. The redline across the strip charts coincides with the bullseye on the track map. Total usage is how much of the tire is being used; 100% braking, 100% accel, 100% cornering or a mixture of each. The more time usage is at the extreme left or right the more of the tire you are using. Transitions in usage are transitions in either speed or direction.

The track map can be divided up into colors to represent any parameter the user chooses. I'm not sure what I will actually end up using but on this map usage over 90% is light blue, between 80% and 90% dark blue, between 70% and 80% violet and less than 70% red. There is so much red on the map because the road was straight and I was not accelerating the car (didn't want to get arrested ), so therefore I was not using much of the tires. If I had been accelerating hard in those straight lines they would have been plotted at a higher usage percentage.

I'm just learning how to use this and plan to race with it all season. The beauty of Geez is that it records these runs and then can play them back in real time overlayed with eachother, as many runs/ consecutive laps as you're computer processor is capable of running. 10 isn't a problem for most apparently. You can immediately see what was different lap to lap and at the same time have hard data. All this comes from a small 2" cube hooked up to a Palm computer. The Palm can store 25 continuous minutes of data and is capable of self starting and stopping itself. It does this by beginning to record once a certain accel threshold is reached and by stopping once a certain decel threshold is reached and maintained for a certain length of time. The thresholds and lengths of time are all user controllable. I had the system on and it began recording when I dumped the clutch from the stop sign; it then stopped after I was parked at the light.



Geez only has one shortcoming. It has no direction gyro, only accelerometers. That means it does not know if the car is slowing because it's going uphill, or cornering not as hard because the corner is off camber for instance. For my use it doesn't bother me; I want to see what is different run to run and since all the runs I am comparing are on the same course they will all read back the same within Geez. This program is more powerful than I realized and I look forward to using it.

Race season not started here yet though

www.extremegeez.com
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Old 01-14-04, 02:30 PM
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Seems pretty obvious to me that with a slightly earlier apex in the second half of the ess, you'll be able to apply throttle earlier, and carry more speed to the stoplight

Looks like a fun toy. You'll be swimming in data soon!
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Old 01-14-04, 03:12 PM
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Right now I'm just happy it all works I need to tweak some of the settings yet but it's close. I did a run on the same stretch of road in the dry, so I went much faster and cornered much harder. I will download that one when I get home, play them back together and post the results.
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Old 01-14-04, 04:15 PM
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How does it determine the available grip from the tires from only two dual-pole accelerometers?
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Old 01-14-04, 06:22 PM
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Here are the plots side by side. The left one is in the wet, and the right one is in the dry. Notice the friction circle on each. Exiting the last ess the friction circle on the wet run says I was using more of the tires' grip since the graph stays closer to the outside of the circle than on the dry run. That makes perfect sense: In the wet I had more engine power than grip so I could use all the grip I had at corner exit. In the dry I didn't have enough power to break the tire loose so the graph shows I used less of the tire at that point (still keep in mind I was on a public road and so wasn't accelerating the car hard). If you look at the lateral strip charts for each you'll see on the top half of the wet run the car was moving side to side even though the road is straight (the top of the chart is the start; the bottom the finish). The lateral g's on the wet run are all over because the car was fishtailing as I was accelerating, on the dry run the car was going nice and straight.



I'm still learning this as I go along but I plan to share this stuff in the future or maybe even instrument some other people's cars to compare the two. The track map itself is useless, it's the numbers the software can apply to that map that is the key. I'm still learning about everything that you can wring out of the software.
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Old 01-15-04, 07:41 AM
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Thanks for the info. Looks like a powerful tool.
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Old 01-15-04, 11:50 AM
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I guess in a comparative sense, this can be a useful tool, especially for auto-x, where you don't want to waste time dissecting loads of information. And for the price especially. I'm just wondering how much useful information you can actually extrapolate from it towards improving your car's performance (as far as the driver's performance, I'm sure there's a lot that can be drawn from it).

Don't get me wrong, I'm not knocking it . I'll be very interested to see what you can do with it in the future. Thanx for offering the info.
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Old 01-15-04, 02:17 PM
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Wow, that looks very sweet... Looks like another little toy I need to add to my wish list.
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Old 01-15-04, 09:32 PM
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That's definitely going to be a must in the near future.

As far the information given by the data, that is really impressive. There truly isn't anything that beats being able to watch yourself move through a course and then to be able to put them side to side and see the different speeds and times through segments. Couple this software with an in car camera and, wow, I can't wait.
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Old 01-16-04, 07:57 AM
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Originally posted by Kento
How does it determine the available grip from the tires from only two dual-pole accelerometers?
I gave a very poor (wrong!) answer of this earlier so I have edited the post!

The sensor inside the car is a 2" cube with two accelerometers in it; one aligned along the length of the car (y-axis) and one across the track (x-axis). The y-axis detects postive or negative accel in a straight line and the x-axis detects accels in the left or right direction (turning). By integrating the two readings together the software can see if the car is straight, turning left and accelerating, turning right and braking etc (the software is also completely capable of generating 0-60 times for instance). The lateral accelerometer gives true cornering g's. The system cannot read topography so a downhill slope will show as a speed increase, or an off camber turn may rate as a lower usage because the software doesn't know that in fact there WAS less grip available at that point.

Because there is no yaw angle sensor the system doesn't know if the car is sliding tail out. Picture a car oversteering into a corner. The map would show as the car turning more tightly than the actual path traveled, speeding up as the car rotated and slowing down as the car straightened back up. The raw map would be diplayed this way but it can easily be fixed once downloaded. The key is that first you knew you were tail out sliding and the second is that turn on your map will look screwy. You can fix these areas very easily and quickly with tools in the software. With GPS being so cheap and accurate now Geez! is working on developing a new version whose track maps would be absolutely true.

The pitch and roll of the chassis during manuevars can cause drift in the accelerometers and therefore errors. That is why there is a correction factor that you can compute and enter for your car to take care of that. The software essentially will filter pitch and roll out of its results so that the readings are true.
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Old 01-16-04, 02:31 PM
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I have to share this one

A friend who has ridden with me before asked about this whole datalogging thing and what it could do. He asked if it will do this, that and the other thing and I explained it would.

He emailed back and said "Yeah, but will it show the point on the track where I screamed out loud and **** my pants?"
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Old 01-16-04, 07:56 PM
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Originally posted by DamonB
I gave a very poor (wrong!) answer of this earlier so I have edited the post!

The sensor inside the car is a 2" cube with two accelerometers in it; one aligned along the length of the car (y-axis) and one across the track (x-axis). The y-axis detects postive or negative accel in a straight line and the x-axis detects accels in the left or right direction (turning). By integrating the two readings together the software can see if the car is straight, turning left and accelerating, turning right and braking etc (the software is also completely capable of generating 0-60 times for instance). The lateral accelerometer gives true cornering g's. The system cannot read topography so a downhill slope will show as a speed increase, or an off camber turn may rate as a lower usage because the software doesn't know that in fact there WAS less grip available at that point.

Because there is no yaw angle sensor the system doesn't know if the car is sliding tail out. Picture a car oversteering into a corner. The map would show as the car turning more tightly than the actual path traveled, speeding up as the car rotated and slowing down as the car straightened back up. The raw data would be diplayed this way but it can easily be fixed once downloaded. The key is that first you knew you were tail out sliding and the second is that turn on your map will look screwy. You can fix these areas very easily and quickly with tools in the software. With GPS being so cheap and accurate now Geez! is working on developing a new version whose track maps would be absolutely true.

The pitch and roll of the chassis during manuevars can cause drift in the accelerometers and therefore errors. That is why there is a correction factor that you can compute and enter for your car to take care of that. The software essentially will filter pitch and roll out of its results so that the readings are true.
That's kind of what I was getting at. You'll be able to know that you slid in one corner during one run/lap, but it may be difficult to exactly ascertain why. True, you can look at the acceleration figures and x-axis figures to see if you were coming into the corner hotter and perhaps exceeded the tire's available traction, but could it have been you inadvertently turning in a bit harder for whatever reason and then causing more weight transfer? Or perhaps slightly increased throttle application right before the turn-in point that was enough to bring the rear around? Won't both will show up in the data as increased Gs up to the point of traction loss?

Sorry, don't mean to be the devil's advocate, and again, for the price, you're getting a hell of a lot of good information. I'm just wondering, that's all....
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Old 01-17-04, 08:18 AM
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Originally posted by Kento
Sorry, don't mean to be the devil's advocate, and again, for the price, you're getting a hell of a lot of good information. I'm just wondering, that's all....
That's pretty much the point as always; price. In order to be "perfect" you would also need a yaw sensor or GPS. The systems I am aware of that have this capability are much more complex ($$$), more highly integrated into the car (hard wiring and sensors) and require an actual laptop to run them. Even with all the measurement potential they pocess many who use these other programs (MaxQdata is one I have heard mentioned several times) have told me that their data analysis programs are either complex or downright unfriendly and difficult to use. Geez! in car installation consists of a 2" cube that can merely be velcroed down, a small battery box that holds a nine volt and a switch and the Palm computer itself. This will allow you to record 25 continuous minutes of data. The Palm itself can store several 25 min sessions, but they have to have stops between them. I'm told that has something to do with the Palm hotsync operation that downloads to the computer and the computer only being able to handle strings of a certain length at a time. Because of this the tiny Palm can actually store more raw Geez!data than a laptop!

Geez! was originally invented back in the early 90's and became a marketed product in the late 90's. Back then GPS was an expensive luxury; now it's common. Their goal was to always sell this product at a certain price point and Byron says he does not wish to develop an expensive package; the goal was always to be affordable. With the in mind I'm told that the next generation of Geez! will probably incorporate another sensor. Best of all is that Byron's upgrades are always free (I'm sure a new sensor package would cost though). Once a Geez! customer, you're a customer for life.
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Old 01-17-04, 07:22 PM
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Can you use a laptop in place of the palm? Also, datalogging devices I've seen store the information in their own memory and it is then downloaded to a laptop (or what have you) after the run. Is this how Geez! works, or does it feed real-time into the computer?

Thanks a lot for guinea pigging this for everyone Damon
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Old 01-18-04, 09:31 AM
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the problem with the lower price systems is exactly what kento was alluding to....it gets hard to seperate car issues from driver issues. a little data is ok, but frequently it will leave you with more questions than answers.

i'm presently researching this topic cuz i'm soon to install a full system in my racecar. the best systems these days are made by motec, pi, or stack.....they are very powerfull, multichannel acquisition systems. (check out www.veracitydata.com for a preview)

at minimum i think you need the accelerometers, shock position (downforce), throttle position, brake pedal force, steering position, yaw, speed, gear, rpm.....

the smaller systems are mostly helpful when you can compare them to another drivers plots.....ie.."oh, his turn in speed is 1mph higher, or his brake point is 3 meters earlier" that kind of stuff.

good luck
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Old 01-18-04, 09:39 AM
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You can use a laptop as your storage device but in fact the Palm can hold more info than the laptop. I know that seems odd, but it's true.

The Palm itself is merely used as the recorder in the car; it doesn't give you any info about the stored data other than the date, length of tiem of each record period and catalogging the runs currently in memory. There are simple programs that Geez! loads into the Palm in order for it to perform the functions Geez! needs. You can't do any analysis until downloading the Palm to a pc or laptop. The true product with the Geez! package is not the sensor, it's the software.

Once the data is downloaded from the Palm and into the Geez! analysis software (which takes all of 2 minutes max) you can see anything you want. Most of the guys bring their laptop to the track and leave it in the pit. Then after a morning run session they will download the Palm and look at what they've got on the laptop in order to show what they can try doing different in the next session.

Since the Palm is merely a storage device there is no sense in buying the latest and greatest Palm just for the use of Geez! I'm using a previous generation M100 which is about the size of a handhled calculator and works beautifully; payed less than $100 for it. ebay is even cheaper.

When you buy the software you get a parallel port key for your computer in order to enable all the functions. You can download the trial version for free which is fully functional other than not allowing you to download runs into it, you can only view the half dozen or so examples present in the trial version. Other than that the analysis is fully functional so you can see for yourself the type of info available.

www.extremegeez.com
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Old 01-18-04, 09:53 AM
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Originally posted by foko
the problem with the lower price systems is exactly what kento was alluding to....
If I had $3000+ to spend on data acquisition and a trailered car I certainly would have headed the direction you are. For now Geez! is going to tell me what I need to know. Your idea of driver comparison is right on but realize you can compare yourself to yourself; you don't need another driver. I want to know how various attacks on the track affect lap and segment times. I can try different ploys on different laps and see immediately how my different approach added to a gain or loss in any segment I choose. I can also instantly see not only if it helped me in a segment, but also if it hurt me in the next one. At the same time I want to educate myself some more on car dynamics by using this before I inundate myself with data.
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Old 03-12-04, 11:33 AM
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Damon,

How much do you get yours? Is it the Racer Package?
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Old 03-12-04, 11:55 AM
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Originally posted by reza
Damon,

How much do you get yours? Is it the Racer Package?
Yeah, I got the Racer's Bundle. I was all set to buy the thing and thought for the hell of it I would check ebay first. I was completely floored to find one up for auction in like new condition! There weren't any bids so I made an offer to buy it right then, but the seller declined. My winning bid was less than I was going to offer in the first place I'll never have that kind of luck again; about half price!
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