cgomez

I was able to run both my cars at LRP last week. Got some telemetry to compare both cars with some predictable results. Slightly better weather on Saturday when I ran the 997S (warmer, so maybe more grip but less power).

Below is a 1:03.2 lap in the lotus Elise and a 1:01.5 lap in the 997S.
My driving technique in both cars is similar (mid vs rear engine) but it pays off more to give some speed early and get full on the gas earleir in the 997S b/c there's a lot of grip back there despite more power.
Corner speed and G-loads are higher in the Elise (same tire compound in both - Toyo RA1s), but the 997S brakes harder (Peak braking 1.36G vs. 1.1G).

G-forces and speed (997S tops 130mph while the Elise a mere 118mph):


Friction Circle Elise:



Friction Circle 997S



If you analyze sector times, only in the section that includes left hander and quick kink to the right, the Elise matches the 997S time. In any other turn, despite higher corner speed you can always pick a line (earlier-late-apex) that allows you to be faster overall in the more powerful car (assuming it handles decently). Tough to overcome a 165hp deficit in a track that averages 85mph+

Anyone else has traqmate data to share for this Track?

Geoffrey

While not traqmate data (it is MoTeC), for comparison, here is some data from 2 weeks ago at Lime Rock. First time at LRP in my new car on a green track with old slicks and less than stellar conditions. Some data from Bob Scotto's drive in my car. This is also a repost of something I posted on the 964 forum.

1) Track Report - this graph can show one lap, or a reference lap with one or many laps. In this case, I laid out Bob Scotto's best lap and my best lap which graphically shows throttle position and identifies gear, max section speed. The inside lap is my lap set as the reference lap, and the outside is Bob's best lap. You can see that for turn 4 and turn 5 he is on the gas earlier and longer which is giving him a faster corner exit speed.

2) Section Report - this graph lays out both laps and shows data for each section. You can see his minimum corner speed for turn 5 through turn 6 is much higher than my laps. This is consistent with him getting on the gas earlier and longer as well as braking less.

3) Section Times - this graph shows the section times for each lap. The blue cells are the fastest section times for all of the laps. The green shows a section that is within a certain percentage of the fastest section time. The eclectic lap is the fastest theoretical lap based on the fastest section times. Shown here includes 6 sections from lap 31 (bob's lap) and 6 sections from my laps.

4) Braking Data - These are just channel vs time plots that show the two laps overlaid and we can begin looking at detail data for the back section of the track. You can see he presses the throttle earlier and the corner speed increases. You can also see he is braking later.

5) Cornering Data - again, various channel vs time plots that show corner data. The car is generating almost 2g of cornering. I have not yet connected my steering position sensor, so there is no data for steering angle and computed oversteer.

6) On lap 46 I spun in turn 3 (the left hander) Here is the data showing wheel speeds and associated g-force. Unfortunately, I don't have my streeing potentiometer installed yet, so I can't see how the steering wheel is turned. You can see that as soon as the car reached 2.25g it began to spin and I was not fast enough to catch it.

7) Brake zone of turn 1 (big bend) which is bumpy and causes wheel lockup when threshold braking. My car has racing antilock brakes and you can see the FR lockup and the ABS kick in to release just the FR wheel. You can see the same for RL

8) Is at the crest of the uphill which shows wheel spin as the car gets light and you are full throttle. I did not have the traction control active as I have yet to find that the car really needs it on a dry surface. I need to spend some time with it in a controlled environment to adjust it. The traction control is based on throttle position vs ground speed with a trim for lateral g-force and a dash mounted trim **** to adjust the amount of wheel slip permissible before the ECU activates the traction control function.

9) Here is the friction circle. I hesitate posting it due to the conversation about a year ago with Colorchange on this forum.

cgomez

Wow!

Definetively that piece of software and data box makes Traqmate look like PreK stuff!!
Amazing. if mine where a racercar I would hook up somehting like that!

From the basic G-forces readout you can deduce stuff like air-wheelspin at the top of the Hill (hiccup in acceleration and is not a gear-change) but obviously not as precisely.

Thanks for sharing.
I pressume this also comes with a very neat on-Board display for lap times, sector times, etc...

jgrant

Very cool. I'm in the process of writing my own (Java-based) software that I can use to interpret my TraqMate data, and the Motec stuff is very interesting... I've never seen it before.

Just out of curiousity, how do they calculate/measure the degrees of oversteer?

Geoffrey

I'm not a math expert and the MoTeC Interpret software has a sophisticated math calculations you can use. Oversteer/understeer can be calculated using different formulas. Here is one OSUS = [steering angle - (wheelbase x lat-G x constant)] / (speed x speed)

jgrant

Ahhh... k.. thanks. That makes sense.

Also, have you ever seen any Vertical G forces measured? I've seen lots of lateral and longitudinal forces measured, but no vertical. I always thought that would be extremely useful for cresting turns, etc.

Geoffrey

Yes, I have a 3 axis accelerometer in my car so it measures vertical as well.

SundayDriver

You can also do that with a MoTeC math channel if you have shock pots. You get travel, shcok speeds, g's and can even turn it into front and rear downforce along with center of pressure.

MoTeC is an incredible tool, as you can see from the data. You can now also integrate video into the data layouts.

cgomez

Sounds like a great plan, let me know how can I help. I have some ideas about how to make Traqmate really useful. I'm not versed at coding but decent with math and physics and how it translates into driving dynamics.

I think a lot of the info interface you see in the Motec can be done with the Traqmate data. Calculating Yaw-rate and having an "auto sector split" fucntion would be the 2 things I would choose to get first.

jgrant

Thanks, I'll keep that in mind. I have 3 software companies, and have some really good coders that have some free time on their (well, MY) hands, so I've started them working on this.

My goal is to create some 100% Java software so that you can run it on any system (I'm a big Mac fan, and everything seems to be Windows based) and can read any file format. I'd really like it to be something that you can use to compare ANY data, regardless of the system. In other words, I'd like to be able to run the software on any system, and read MoTec, TraqMate, and any other type of system, and display that data as well as allow you to run comparisons between the sessions.

I'd also really like something that addresses the "issues" I find with the existing TraqMate software... the GUI is a little lame, IMO, and has some real usability issues.

I'd love to get a hold of some Motec data so I can figure out how to interpret it. *cough*

I figure I'm about 6 weeks away from releasing a "beta" version of my software, which will act as a replacement for my TraqMate software. I'm also thinking about making it Open Source, but I'm not sure yet.

My biggest issue so far is that I'm incredibly limited in the data that I can collect, as I have an old '82 turbo that has electronic NOTHING... the only inputs I have are the TraqMate sensors and anything else I add onto the car myself. I'm currently putting together a list of sensors/inputs I'd like to add to my car, and sourcing some of the hardware to accomplish that.

I'd be really interested in your (or anyone's, for that matter) opinion on what data is really useful for this kind of system.

For me, I'm an INCREDIBLE newb at this "race car driver" stuff, but find the telemetry to be VERY interesting. The engineer in me really finds the information usefull... it allows me (and not my ego) to really see what happened on my last session, etc. It really is amazing how you tend not to remember things how they really went.

I've set up my TraqMate to be quite portable, and have gathered some interesting telemetry from other cars/drivers at various tracks, and use that to really analyze my mechanics.

I'm really looking forward to my next track date (Oct 4th) when Patrick Long will be available as an instructor. I'm hoping he can take my car for a few hot laps so I can get some REALLY good data for my car.


Anyway, I'm babbling (could be the wine.. long day!) but if you're interested in this, by all means, PM me your email address and I'll get you involved... the more the merrier!


...jeff

Z-man

Geoffrey - thanks for posting those - that is some amazing detail.

-Z

Geoffrey

Cgomez, Is there a way to add RPM and throttle position to your logging? I believe they are the two most important channels to log. I would assume that on the 997 with DBW, that may be difficult without communicating directly on the CAN bus.

Jeff, email or call me and I can send you some MoTeC log files. There are several formats I can put it in from native to a .CSV file.

Z. Over the winter the car will get 4 shock position sensors and steering angle sensor. From there I'll be hooking up my power steering which will be activated using a PWM controller where the MoTeC ADL will output a PWM signal based on wheel speed and steered angle and the PWM controller will output between 2-12 volts for the power steering pump so it runs only when needed. Other sensors I'd like to fit are 12 tire temp, a CAN based tire pressure monitoring system, and ride height sensors.

Gary R.

Geez Goeffrey, when will you be putting in the Motec Driver module? Sure will save a lot of sweat, getting in, steering, working the gas/brake, etc!!

analogmike

Jeff,

Being able to compare AIM MXL data and MOTEC data would be very popular with us cup car guys. I also have the Innovative Motorsports logger on my old car with lots of data I could send you...

good luck!

cgomez

I tried to connect the rpms but the installation requires more time since its a 5V output instead of 12V which is straighforward.

You can add many data channels (8?) but my unit is portable b/c I share it between cars.

What I will do to is to overaly the telemetry over the Video so you can see the steering input. My main take away from your Motec post is how good the user interface can be.

You can do most of the above analysis with GPS position, speed and accelerometer info only. It's mostly about how you convey that info. The side by side of reference vs. current lap chart is EXTREMELY useful, and splitting the lap time data by fixed sectors is a must too.