Intro to Data Acquisition

How to get started analyzing your data for driver improvement

By Vaughan Scott and Ralph Provitz

Photo by John Gacioch© 2007, V. Scott, R. Provitz

Overview

• Data Acquisition Systems, or Data Loggers, will continuously save a number of data, or channels, while on-track. These usually include speed and lap times, at a minimum.

• A dash display can provide the driver information such as lap times, RPMs, speed, gauge info, etc.

• Data can be downloaded to computer for a detailed, second-by-second, corner-by-corner, lap-by-lap dissection of performance.

• This data can be used for improving driver performance and to tune engine and suspension for better performance.

• What follows is a more detailed discussion of basic techniques for analysis of data to improve driving technique.

Data System Comparison

GPS-Based

• Pros:– Great portability/ease of

installation

• Cons:– Resolution?

• Systems:– Racepak, Traqmate, Racetech...

Speed Sensor/Beacon

• Pros:– Better accuracy/repeatability (for

data comparison)

• Cons:– Harder to install

• Systems:– AIM, Motec, Pi, Stack…

General considerations:

Ease of comparing data with other drivers/cars is a plus; consider getting the same system as other drivers in your group/class to make this easier.

Costs – starting at just under $1000 per. Make sure what sensors are included.

Also – Dash display, predictive lap times, Math capabilities, CAN/OBD2 interface to ECU, ease of adding new/different sensors, # of channels, sampling rates, memory size

Who Makes them?GPS-based:

http://www.g2xtreme.com/ - Racepak G2Xhttp://www.traqmate.com/ - http://www.race-technology.com/ - Racetech DL1, DL1, etc.

Sensor-based:http://www.aimsports.com/ - MyChron3/4, MXLhttp://www.motec.com.au/ - ADL2http://www.stackltd.com/ - Stack Dash-Loggerhttp://www.piresearch.com/ - X Sport, Delta, Sigma, etc.

Basic signals for evaluating driver performance:

Speed

RPM’s

Lateral G’s

Longitudinal G’s (accel/decel)

With at least one or two of the above signals, we can start to draw some conclusions about what the driver’s doing, and what can be done better.

Additional signals for evaluating driver performance:

Steering angle sensor

Throttle position

Brake pressure

There are additional sensors that can be added to further indicate what the chassis is doing – yaw rate, shock potentiometers, etc – but these 3 are the more important driver feedback channels.

Strategy for Data Analysis

• Find corners to improve, and find corners to not push harder on.

• Take good notes.• At the track – don’t overdo data analysis.• Between weekends – look at more laps,

look for patterns, find strong and weak points.

• Don’t just look at the fastest lap from each session; review all your laps.

Guidelines

• Filtering – be aware of filtering.• Get LOTS of data!• Consistency is key.• Make sure you’re hitting your marks.• Data systems only tell you what you’ve

done, not what you can do:1. be consistent2. do something different - deliberately

Data evaluation

1. Review fastest laps.2. Look for big obvious issues:

• wheel spin on throttle• rough or ragged driving• lazy or over-aggressive corner entry• Off-line driving

3. Identify and evaluate areas of interest.4. Find problem areas. 5. Look for consistency high and low points.6. Detailed comparisons of lap time.

7. Take detailed notes, put them with your gear, and make sure they get to the track next time!!!

Data Analysis - Examples

• Corner entry – too fast, too slow, good trail-braking• Recognizing oversteer• Recognizing understeer (?)• Friction Circle analysis• RPM data - Shift point evaluation• Car power (acceleration) comparison• Detailed comparison of lap times – statistical tools, lap time

deviation from a baseline

Data Analysis – Basic lap plot

This line

Corresponds to this point

Lateral G’s

Speed

0 G’s + RH

- LH

Data Analysis – Corner entry too fast – Turn 5

Lateral G peak at corner exit

Car slows through corner

Data Analysis – Corner entry too fast – Turn 5

Earlier lateral G peak in grey lap: earlier turn-in

Car exits corner faster

Compare speeds

Data Analysis – Corner entry too slow – Esses

Late lateral G peak at corner exit

“Sawtooth” speed trace

Data Analysis – Corner entry too slow – Turns 1-2

Driver accelerates to apex

Data Analysis – Trailbraking technique – Paddock and Esses

“Bowl-shaped” speed trace

Data Analysis – Recognizing Oversteer – Turns 1-2

Whoops!

Data Analysis – Recognizing Oversteer – Turn 3

No sliding!

Earlier turn-in on grey lap prevents oversteer

Data Analysis – Recognizing Understeer – Turn 1-2

Turn, baby, please!!!

Tires give up, car stops turning here

Lateral returns as steering returns

Data Analysis – Preferred – Turn 5

Little bit of a slide here

Corner entry: smooth transition from braking to cornering

• The Friction Circle plots your lateral and longitudinal (accel/decel) Gs on one chart.

• Easier side-by-side driver comparison.

Poor Trail Braking Good trail Braking

(same car, different drivers)

The greater the area, the more you are

taking advantage of what grip your car has

This is very helpful to show trends in driving and what you need to change to improve.

It also shows the problem is not the car but the device between the wheel and seat.

RPM eval – shift points – exiting Turn 2 to kink before Turn 3

Can this be avoided?

Spec Miata, two different cars – Turn 5

Look at the slope between cars –what is the red car doing differently?

Segment Report. Are you consistent?

Fastest lap of the race

Lap times for each lap

Green Blocks show segments that are faster than your fastest lap

In your dreams!

Lap Time statistical analysis

Is this realistic?

Is this?

Lap Time Comparison

How do we do this again?

Summary

• Focus on speed above all else.• Figure out where you’re good as well as where you’re bad.• Set achievable, measurable goals.

• Waterford-specific thoughts – • Important corners for speed• “Throw-away” corners• High-risk corners

Added thanks to Mark Dalen for his support and direction in putting this presentation together.

Photo by Bubba Albo