Larry Herman

I am thinking about a DA setup for the car for next season. I think that I can setup the car pretty well by feel and lap times, so my main objective with this is to be able to observe my driving and work on improving various corners. The video that I have taken has been helpful, but marrying it to data via trackvision will provide more information. I think that sector times will be especially helpful.

That being said, what other items of DA would I need? I guess that first is a good unit (suggestions welcome) and then the various inputs. I think that RPM, throttle and brake positions are required. Is steering angle necessary for what I want? Any other recommendations would be helpful.

Geoffrey

You'll want the following:

TPS - from there you can differentiate and get throttle rate of change and you can smooth it to determine throttle agressiveness.
Steering ange - from there you can differentiate and get steering rate of change and you can smooth it to determine driver smoothness. Combined with lat-g you can get an indication of under/oversteer.
Brake pressure - from there you can identify areas of the track where you are not on the throttle and not on the brakes - ie coasting. You can also differentiate and get brake speed and smooth it to get brake agressiveness.
g force, both lat and long - from there you can identify the corner radius if you also have wheel speed
Wheel speed - used for some calculations and will help identify corner exit speed as well as minimum corner speed.
RPM to help identify what the engine is doing

If you have adjustable shocks, you should have 4 linear potentiometers on them so you can properly set up the spring rates and shock settings. you can get over 60 pieces of information about the chassis from JUST 4 shock position sensors.

Of course you need a good DAQ system software to help you. The GPS based systems aren't fast enough to do most of what I mention above since they sample at 10hz and they don't have robust software with math capability to do calculus. You also want a system where you can export to an Excel spreadsheet for further analysis.

I would start by looking at the software the systems provide to ensure it is flexible enough to do more than draw "pretty track pictures".

SundayDriver

What he said.

Take a hard look at the real math capabilities of any system. All claim they can do math channels. But most of the low end systems have real shortcomings in terms of ability to actually write the math and to change the calculations. Simple things like changing spring rates are very difficult to handle in the cheaper systems. I am convinced that you get what you pay for and that is why I am such a MoTeC fan. Many of the low end systems will never really give you the calculations that Geoffrey mentioned.

Veloce Raptor

It always pays to have a good "unit"....

kary993

I think you have been given some excellent input. I would add the following:

1. You need to be knowledgable about how to use the features mentioned in this thread.
2. You need to be knowledgable with a computer to play with data no matter the software package.

I have been using a G2X system which can provide all that has been mentioned here. I do not agree with the GPS comment made here. This unit offers any calculations you might want to make, it offers the G loads, speed without the need for wheel spin calcs, and offers a Throtle/Brake/steering package that easily adds on to the system without extenive calibration of the sensors to the system, unlike others both low and high end.

I have seen a number of people really siuffer with MoTec and Stack, so be warned if you go that route.


If you are interested in learning more about the G2X call me and I will answer any questions you might have as well as what sensor options are offered. Purchasing from me also provides you with technical support to get you up and running with your analysis or other questions.

SundayDriver

Kary,

How does a GPS system do over/understeer? I have seen claims that using 2 sensors (front and rear) will do it, but the physics make that very doubtful.

PatK-Mpls

For driver feedback: rpm, wheel speed, brake pressure, steering wheel angle (you can do a poor man's over/under steer w/ addition of 2 axis g w/ steering angle), gps (or g's) to do mapping and then some form of segment times

For setup: shock pots and ability to do some form of analysis w/ data (differentiate, histograms)

For car monitoring: oil t, oil p, fuel p, etc

IMO the G sensor data is far overrated. I do not use any g data in analyzing my data or comparing it.

AndyT

Geoffrey what do you recommend for a good starter system for data logging ? I was thinking the GSX. However your comment on GPS has me wondering. I'd love to go Motec but the budget does not allow at this point

Geoffrey

There are some incomplete definitions here. You cannot find understeer/oversteer using a single accelerometer and steering angle. You CAN find indication that under/oversteer is occuring, but that is incomplete and not necessarily accurate in all cases. You NEED both a front and rear accelerometer AS WELL as both a front and rear slip angle sensor to accurately determine under/oversteer. Understeer occurs when the front lateral accelration/front slip angle is less than the rear lateral acceleration/rear slip angle. I think this is the largest difference between the low cost entry level systems and a true accurate DAQ. The low cost systems give you incomplete information.

As far as GPS systems, at 125mph, the distance between GPS samples is 220 inches that is 18 FEET. I know that a lot can happen in 18 feet as far as yaw angle, g-force, suspension movement, braking system, etc.

The only reason you've seen people suffer with MoTeC systems is either the price they paid if you believe that it is expensive for what you get, or they aren't able to use the I2 software to get the most use out of it, or don't have the most appropriate sensors connected to it.

SundayDriver

So are you going to disclose the pricetag of the slip angle sensors? LOL

BrianKeithSmith

Geoffrey/Sunday Driver:
What are your opinions of the AIM MXL Pro? That's one I've had my eye on.

Larry - not trying to steal your thread!

Brian

Larry Herman

This is the problem that I see with DA. One camp says that the GPS stuff is too simple, and the other says that the high end stuff is way too complex. At the moment, I am not interested in the race technology aspect of DA. I want it to evaluate my driving, and work on finding more speed through optimal lines. To my way of thinking, that is video and sector times.

Perhaps the more sophisticated equipment, if it can be used easily may provide additional information that I can use, including analysis of the car setup. If that process takes hours and hours though, I can't see me doing that.

Geoffrey

The AIM MXL series is actually quite good and does come with the ability to write math channels. The Pro is approaching the price of the MoTeC Sport Dash. Both have the ability to use video combined with data logging. The AIM system is called DaVid while the MoTeC system uses ChaseCam equipment and allows viewing of the video directly in the I2 software where you can put a time/distance graph on screen along with the video. Both are supported by TrackVision software which is more for viewing pleasure than data analysis.

Larry, there is no free lunch...the more you want to learn about your driving, the more time you'll spend looking at the data and could quite be hours and hours, especially at first.

PatK-Mpls

Larry-

There are different GPS formats. A system that uses differential GPS is much more accurate than regular GPS (SA removed).

As for the question about AIM: I have both AIM and MoTeC in my car (long story why both). The software (I2) on the MoTeC is probably the reason I use the MoTeC 90% of the time.

If you look at a MoTeC there are a couple things to bear in mind: 1) The ADl Sport is more than sufficient for most amateur racing efforts and 2) You need ProLogging to do video

AndyT

I was under the impression that Motec and AIM system could not interface with the 993 Motronic ECU ?