Monday, December 3, 2012

Data Analysis Part 1 -- The Basics

I have been wanting to write a post on data analysis for a while now but there is so much to it that I have had difficulty figuring out how to approach it.  There is no way I can cover everything so hopefully these posts give a basic understanding of what can be accomplished with data and just how important it is for getting the most out of the driver and the car.  Plus, there is lots more detailed information out there already if you know where to look. 

If you have a data system in your race car then you really need to take John Block’s (www.auto-ware.com) online seminars.  John is an engineer that has A LOT of experience performing data analysis for professional race teams.  John offers a basic course and an advanced course.  They are 1 hour a week for 5 weeks and I believe that they are only $125 for each course.  John also allows you to re-take a course at no additional cost.  I actually re-took the advanced course after I had started using some of the principals taught which helped me better understand what John presented.  You can’t beat that!!  Chances are that if you haven’t taken his courses then you aren’t getting the most out of your data system. 
Bob Knox is another data analysis expert and he has a book out called “A Practical Guide To Race Car Data Analysis”.  Bob has tailored this book for the amateur racer so it is easy to understand and as a result I have referred to this book quite a bit.  It costs $100 and it can be found on amazon.com.  Definitely well worth the money.
Ok, here are some basics.  A data system is simply a small computer that is gathering information from various sensors.  The G (lateral, longitudinal, and vertical) sensors are built into the main unit and the other sensors are manually installed.  Since the Honda Engine has an ECU, I’m able to get a lot of information directly from the ECU which is great because you only have a certain number of “channels” to use to gather data.  Generally you hook up one sensor to a channel but with the ECU interface it is possible to get lots of info through one channel. 
Now, here is the real power of the data system.  Not only do you have the raw data from the sensors, you can create virtual sensors by creating what AIM calls “Math Channels”.  Math Channels are simply formulas that use data from the installed sensors, constants (such as your cars wheel base), and/or data from other Math Channels.  Some Math Channels can be quite complex but a lot of them are quite simple.  For example, I have two wheel speed sensors installed on the two front wheels.  Obviously there is a chance of me locking up one of the wheels under braking and although I want to know about this, I also want a smooth speed trace so that I can see how fast I’m going anywhere on the track.  Therefore, I created a “Selected Speed” math channel that simply says: use the average speed between the left and right front wheels but if one wheel is locked up then use the other wheel speed instead.  Obviously the formula looks very different than what I just wrote but in order to write the formula you have to be able to describe what you want it to do.  Here is the formula:

IF(LT(LFspeed,.97*RFSpeed),RFSpeed,IF(LT(RFSpeed,.97*LFspeed),LFspeed,(LFspeed+RFSpeed)/2))

The AIM syntax is a little different than what would be used in Excel or most other software programs that I have used before but once you get used to it isn’t difficult to understand.  If I saw this formula for the first time then this is how I would describe what it is doing.

If the Left Front Speed is Less Than 97% of the Right Front Speed than use the Right Front Speed.  However, if the Right Front Speed is Less Than 97% of the Left Front Speed than use the Left Front Speed.  If neither of those two conditions are true than take the Left Front Speed and add it to the Right Front Speed and divide that total by 2 to get the average. 

Hopefully all of that makes sense!! J  What I really hope is that you can see the value of using the math channels feature of your data system.  I’m not going to show all of my math channels but I have over 50 and I will say that you can learn about all of them by taking John Block’s courses and purchasing Bob Knox’s book.  There are very few products that I shamelessly plug but these have definitely helped me a great deal and deserve the plug.  Although, I shouldn't be giving it because I know I'm helping my competitors. J

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