Friday, February 8, 2013

How-To: Using Corner Radius in DigSpice Driving Analysis Playback

At first glance, the information displayed on the screenshots of the DigSpice Driving Analysis Software may be overwhelming for some. Let's break down one of the overlooked features of the software, the "Radius" feature. Here we will take an in depth look at a driver's data recorded at Streets of Willow in Rosamond, CA. Vehicle is a Honda S2000.

When viewing data in the Driving Analysis Software, you will see sliding triangles that rise and fall as a driver/rider enters and exits a turn. The rings (shared with the G-indicator), are marked in increments which help you gauge the severity of the turn as the driver is making the turn. "G" or gravity (lateral acceleration), is helpful in understanding how close to the limit the vehicle is taking the turn. However, a driver may not understand why one lap was faster or slower, despite entering the turn at the same speed and cornering just as "hard" as the previous lap. Where is that time being lost or made up?

Some data loggers will show you your driving line, but even fewer will tell you what's really going on besides speed, heading, position, and lateral G's. Understanding the "actual" corner radius you take through a given turn can be used to your advantage. A vehicle that is driving in a straight line has an advantage over a vehicle that is turning. Basically the straighter and smoother the line, the faster you can enter and exit a turn. In short, a vehicle passing the same turn with a wider line, or a line that minimizes steering at the end of the turn will be able to get on the accelerator sooner. Studying the line and experimenting with different entry and exit points can also help you traverse through sets of turns or a particularly difficult turn.

Let's take a look some screenshots from the DigSpice Driving Analysis Software. Below we have the same driver in the same vehicle, on the fastest two laps recorded that day. The red line represents the fastest lap time, and the blue, second fastest. The driver was almost neck and neck throughout the runs up until the final turn (as can be seen by the overlapping graph lines at the top).

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Taking a closer look, we can see that the driver has entered the corner at exactly the same line as the previous fast lap (talk about consistency!). The entry speed into this low speed section is nearly identical, as are the real-time turn radius and corner G's. However that's where all the similarities end as we'll see in the next shot.

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The driver during the previous fast lap (blue) is still ahead at this point. So what has changed? The obvious difference is the line the driver is taking during in the red outlined lap. What may seem like just a small difference in the line makes for a huge difference at the end of the lap in the last 2 turns. We can see that speeds are relatively close, but the driver is taking a wider line during the red run by a small margin.

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Now let's study this next section. By taking a straighter line to the last corner, the driver has now positioned himself in a way that he can make a nice smooth arc around the last turn. This is a particularly tricky part of the track as it is part of a skidpad (just a paved lot with no course markings). Drivers here need to decide for themselves which line is best to take.

Although still behind, we see that during the "red" lap, the driver is taking a much, much, wider radius, allowing him to carry more speed through the same set of turns without exerting as much lateral-G's as the "blue" lap. We can clearly see the difference by the position of the Radius, lateral-G's, and speed marked on the screenshot. Although you would not typically see these slight changes in line in a video recording or by studying the line itself via GPS, analyzing the real-time turn radius may tell a different story. Let's see what happens once the driver enters the final turn...

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Again, driver is maintaining the same speed, at the maximum end of it's mechanical grip (lateral G's) in both instances. Both vehicles are also taking a similar radius during the turn. We see in the line that during the "red" lap, the driver is making almost a perfect arc into the final section of the turn before the straight. Let's see what happens to the vehicle during the "blue" lap.

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During both laps, the driver had maintained nearly identical corner speed, G's, and radius. However, the driver during the "blue" lap now faces a dilemma at the end of the turn. In order to prevent overshooting the end of the turn, he has had to scrub speed in order to make the turn. At this point the vehicles are both travelling at about the same speed, and are at the same location on the track. However, we also see that the driver during the "blue" lap, has had to take the last bend sharper or "harder," unable to get on the throttle as a result. Meanwhile, driver during the "red" lap has maintained a steady arch through the turn and has already begun accelerating being on a wider radius.

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What happens next is quite obvious. The driver during the "red" lap has literally overtaken himself in the previous fast lap by getting on the throttle sooner, allowing him to exit the last turn with more speed (still on a wider radius as can be seen outlined on the screenshot). Within the last few seconds of the lap, this driver was able to better his overall lap time by over 0.100 sec just by making slight changes to his line.

If you ever found yourself in a position where a different driver in a similarly equipped (or identical) vehicle seemed to just "pull away" at the end of a corner... might be time to start looking into your line. Studying the "actual" turn radius throughout different sections of the course will help tremendously. By understanding how to approach a particular turn and setting yourself up for the next bend, you may just find that there may be a second or two (or more) here and there that you would have otherwise missed.

This concludes our how-to section for using the "radius" feature of DigSpice, hope you found it useful. As always, feel free to message us or shoot us an email if you have any questions on how to use DigSpice! The DigSpice II GPS Data-Logger can be purchased directly from our online store at www.DigSpice.com, or through any of our dealers!

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