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Professional Motorsport Data Analysis: Step 4: Analyse Driver

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Step 4: Analyse Driver


00:00 - The next step we want to do is to analyse the driver performance.
00:03 And this is really going to be the meat of the analysis where we're going to go through and have a look at the parts on track where we've got the driver gaining and losing the most time.
00:12 So you see over here on my laptop screen I've got 2 of these runs selected here or 2 of these runs loaded into my project, the way I normally set this up is I usually have my fastest lap which is my pro driver here on the 1:47.74.
00:24 I usually have that as colour and I usually have the slower lap set as an overlay in white in this case.
00:31 So I've got a 1:47.74 vs a 1:48.47.
00:35 So I've just got a really basic setup here that I've got the engine RPM at the top, I've got, this is the corrected speed channel or the ground speed channel.
00:46 I've got the accelerator and the brake, you see I've actually got those shown over top of each other.
00:52 This is optional, you can stack the on top of each other, you can show them on separate lines if you want to, do whatever works best for you.
00:57 I prefer to have them overlaid like this because it just saves me a little bit of screen real estate and means I can look at things a bit taller, I find it a bit easier to see the details.
01:05 We've got the steering channel down here and we've got the gear position channel as well so we can see already some quite big differences between here so let's dig into some of those and see what's going on.
01:14 So first thing I'm going to do here is press F3 and that's going to give us the time variance channel.
01:18 Remember the time variance is the tool that's going to give us the most information the quickest about where someone is losing the most time relative to another lap.
01:27 So first off we see here, we see something really interesting in the time variance channel.
01:32 So the convention we're going to use here is anything below the zero line, so the zero line is the reference lap, that's our professional lap.
01:40 And anything below that line is actually indicating, it's a negative value, it's indicating you're doing better than the reference lap.
01:47 Anything above it is you're going slower, so in this section fo the track, the slower lap is actually doing better in this part of the track, then they lose a whole lot, then they're gradually coming back and then it's pretty stable through this section of the lap and then in this section of the track, the slower driver loses a whole lot of time in a big chunk and then down here they lost a whole other chunk again.
02:07 So that's the convention, below the line's faster, above the line you're getting slower, or certainly the slope of those anyway is going to be important for what we're looking at.
02:15 So what's happening here in this particular case we had the professional driver, while they had a faster overall lap time, they've got a much worse drive out of the previous corner and that's what we see, this big difference here where the, even though the slower lap time's actually making quite a lot of time on the faster lap time here.
02:34 So if we just drag the cursor, one of the important things to understand is that this little legend value here updates to our current position so you can see already by this part of the track, the slower lap time has almost 2/10 advantage even just from this point here from the start/finish line to here.
02:51 Now the first feature on the track that often slows people down in this circuit is there's a little bus stop chicane in this section here and that's the difference we see here.
02:59 Now we can see we've got a massive difference in the way the speed traces look, even though the slower driver has a faster speed trace here you can see there's a big difference in the way they're braking to that first chicane.
03:09 Now as we talked about in the course, we're going to identify the areas of interest based on the time variance plot and that's going to, the steepest places of loss are going to indicate the positions we want to concentrate on.
03:22 So over here I can see straight away there's a really big loss going on here that I want to investigate so that's one loss there I'm going to look at.
03:29 This section here is another big steep loss where a lot of time's being lost and this section here of the track is another steep loss so those are the 3 positions on track I'm going to dig into to start with.
03:38 So in i2 it's just a double click and drag to do a bit of the zoom there and the first thing I'm going to look at is where the braking point is for this first braking marker.
03:48 So I'm going to use our delta function using the space bar.
03:52 So for a start I'm just going to look at where the throttle's been lifted, so I'm going to put one mark there for where the slower driver is lifting and another one here for where the faster driver is lifting.
04:02 Now let's look what is says down here, 44 metres is the distance and again remember it's important when we're overlaying these that we're looking at it by distance not by time and we can see we've got a distance scale on the bottom so we know we're happy there.
04:14 But we're seeing, this time delta in the bottom is showing us 44 metres difference which is a pretty big difference.
04:19 It is a pretty fast corner, this is a pretty intimidating part of the track with this bus stop at the end of this relatively fast section of the track but 44 metres is a really big difference in how early they're braking.
04:30 Now there's a couple of other features I want to dig into here, that's obviously one thing, straight away we can see one driver and it's really obvious in the speed trace how much earlier one driver is slowing with respect to the other.
04:41 The other thing here and the, our legend up here is helpful to us with the brake pressure percentage, you can see here that the slower driver, that's what this feature has shown in here, is using the brake much earlier but also much more aggressively, we've got much more peak brake pressure here so we can see we've got 38, or let's say 39% brake pressure at this point vs 22% brake pressure at this point.
05:08 So already we can see a big difference in the brake pressure magnitude and also in the brake shape as well.
05:13 So what's happening here, the pro, because this is a really fast section of the track, the pro is using a little bit more of a tabletop style brake where they're sort of gently getting onto it, slowing the car down with relatively low and constant brake pressure and then getting off it again.
05:27 And the reason they're doing that is they're not wanting to pitch the car too aggressively, they're not wanting to upset the balance of the chassis too much.
05:33 When you pitch the car very aggressively, the cambers are changing a lot, you're transferring a lot of load from one end of the car to the other really quickly so it does tend to be an unsettling for to the car and when we're heading into a relatively high speed section of track which we are here if we have a look, we're relatively, 140 km/h through this corner that follows that bus stop.
05:52 That's not a section of track you want to be upsetting the car too much, you're trying to carry a lot of speed through there, you don't want to be pitching the car a whole lot in a section like that and that's the sort of braking event that we often see in fast flip/flip sort of areas like this on the track where you're not going to be wanting to change the pitch of the car or the attitude of the car too much.
06:11 So really that's the crux of why it's so different here, at this first turn is we can see that one driver is lifting and braking much earlier but also much more and that's why you see this big difference in the speed track up here.
06:23 We can also see that one driver is going down a gear, so we've got the faster driver which is the coloured line here shown constantly in 5th gear whereas the slower driver is going down to 4th which is often a clue.
06:37 You'll often find professional drivers using quite different gearing selections to what you've got an amateur using and that can be a bit of a hint as to what they're doing with the car, what they're trying to do as far as trying to add some more load to the rear axle, in this case with a rear wheel drive car or trying to keep the car a little bit more settled.
06:53 One of the other things that we see really clearly here in the steering trace, a massive difference is the amount of steering input, the amount of oscillations here in the steering input by the pro.
07:04 That's not to say that to drive the car properly you need to have a lot of oscillations in the wheel, a lot of this is down to driver preference, you'll see different drivers do this in different ways but in this particular case, you've got the driver, the professional driver using a lot more steering input, again it's not necessarily something I'd recommend, it's more of a preference thing.
07:22 It does tend to put a little bit more energy into the front of the car, the front tyres, it also tends to unsettle the car, make the car a little more on edge if you're constantly oscillating it and putting steering input from the side there.
07:33 But again that's just something we see more of a style thing rather than something that's making a fundamental difference to how fast the car is.
07:42 The other thing we see about the steering trace here is the way the car's being steered into the corner.
07:47 So the pro is going much more of a sort of, coming straight into this corner and doing a bit more of a step as far as turning the car into the corner.
07:54 So it's coming along and then quite quickly, quite abruptly putting the steering input and looks like they're driving at quite consistent steering angle until they get to that flip flip of the bus stop whereas the amateur is driving the car in much straighter for much longer before turning in later and that's why you see this divergence in the steering trace down here where the amateur's keeping the car straighter for longer before turning in later in the corner.
08:18 So this is a situation where you've got the pro getting the car turned really quickly and pointing straight at that first apex of the corner and driving the car in quite straight, where you've got the amateur leaving the steering later and putting more steering input later into that first part of the corner.
08:36 So part of this is about the pro trying to keep the load out of the car, trying to put the load early into the turn and try and keep the lateral load out of the turn when you've got more brake pressure later in the stop.
08:50 Again just trying to keep, it allows the car to be driven a little bit harder without upsetting it as much.
08:56 So that's it for that first section, it's a really clear difference, essentially they're just braking a lot too early and also there is a little bit of a difference on how the steering is being used there which is quite critical as far as looking at how much combined load is going into the car as well.
09:09 Let's look at the next section of track we want to have a look at and again we've got a similar story, we can see this loss up here in the time variance, we can see we've got this big difference in the speed trace here and again if we look at the brake and the throttle applications we can see something quite different going on here so I'm just going to press the up key to zoom in a little bit more, give us a little bit more detail here.
09:27 So the point where the throttle's being lifted, let's do a delta between these two and let's have a look at what it says.
09:33 The pro is staying on the gas for 0.4 more seconds or 22 metres longer into that corner and it's a similar thing for the braking application, let's check exactly what it is for the brake application, looks pretty similar.
09:43 15 metres is how much later the pro is getting on the brakes there.
09:47 Now the brake trace is quite similar between them as far as the peak magnitude.
09:53 So we've got the peak magnitude of the amateur here and the peak magnitude of the pro here.
09:58 You can see the amateur definitely has a fair bit more brake pressure fluctuation throughout the stop whereas the pro is able to keep the brake pressure quite a lot more consistent.
10:07 You can see there's these throttle blips happening here because we've got a conventionally manually shifted gear box.
10:13 So the pro is just doing a better job of keeping a more consistent brake pressure on corner entry there as they heel toe down through the gears.
10:19 So really all that time loss again is coming through, you can see we've got this steep section of the time variance here, it's really just because of over braking the car into the corner, so we're braking too early and we're braking to a point where you can actually see even though the speed trace is actually starting to get slightly closer and closer together as you get throughout the stop as the pro is going later on the brakes but the amateur is slowly retarding less as they get further and further through the corner and you can see that because of the difference, if you mentally average that brake pressure trace through there versus what the pro's doing on this red line up here.
11:00 We can also see in the steering trace it's quite different as far as how they're putting load into the car.
11:06 So the pro is doing one jaunt across early in the turn, constant, and then quite an aggressive turn in whereas we've got the amateur doing a much more gradual turn in all the way into the corner here.
11:16 Let's look at the last section of track that we're going to have a look at today.
11:19 This section where we've got this big steep increase in the time variance plot.
11:26 So to show you where we are on track, it's coming up to, essentially another flip flop section of the track where we've, just before we get it onto the bridge before we cross over here, there's a flip flop section before the car heads up over the bridge and again we can see we've got quite a big difference in how the car's being braked and how early one driver's getting off the brake compared to the other, sorry getting off the throttle compared to the other.
11:49 So if we come here and press delta once and we'll press it again, 24 metres is the difference in how much earlier one driver is lifting compared to the other.
11:58 And if we do the same for the brake, it'll be quite similar.
12:03 Yep 23 metres there as well.
12:05 So looking at the brake pressure as well, we have 30% there and we have 15% here so roughly half of the peak pressure that's being used to slow the car down through this section.
12:15 And the big difference in braking point as well is really counting for almost everything that's happening throughout the speed difference here because of the big divergence.
12:26 Now you can see that the amateur is actually getting on the gas quite a lot earlier through here.
12:33 But part of the reason they can do that is because they've overslowed the car so much that even though they are able to get the gas on and drive out more aggressively out of that corner, the reason is that you can see how much less speed they've got through here so there's a lot more grip available from the tyres because assuming they're on the same radius corner there, one's going faster than the other so one's going to have a lot more drive grip available to the other.
12:54 You can also see that there's a somewhat subtle difference in the way the car's being steered into the corner.
12:59 In this case, the pro is doing a bit more turning in earlier whereas the amateur again is driving a bit straighter before turning in more suddenly towards that last corner.
13:10 Again we see because the amateur is driving so much slower through that corner, they're using quite a different gear.
13:17 So the amateur's going down to 4th gear whereas the pro is staying in 5th throughout that whole section and that's really just due to the big difference in speed there.
13:24 So we can see straight away the data is telling us that we have got a almost 17 km/h difference through that section of the track which is a pretty significant difference.
13:34 Now one of the other displays that we know is really useful from the course is using the XY plot or looking at the lateral and longitudinal accelerations to understand the exploitation of the car and I think this is probably quite a good section of track to have a look at that so I'm just going to flick over to the GG diagram here and we're looking obviously at our pro and our amateur here so our amateur is shown here by the white line and the red dots is our pro.
14:00 So we know that the further out we are on the GG diagram, that's going to mean we're exploiting more of the envelope of the car.
14:08 So this is quite a good example of where you've got a typical situation where the driving lines are going to be relatively similar but the speed is much higher from one driver than the other so we know straight away that one driver is going to be exploiting more of the car laterally.
14:22 So by looking at this plot here, it's really clear, we see that pretty typical shape where we're much further out on this combined section through here than we are for the amateur.
14:32 If we just zoom out a little bit more you can see how we're zoom linked like we expect and we can add more and more of those points in but you can see how important it is to zoom into the area of interest to get rid of the clutter to show more clearly what you really want to look at.
14:44 So those are our 3 sections that we are identifying as our points we need to work on with our driver.
14:49 Now we can take those 3 positions on track and whether we're doing this analysis for ourselves or whether we have to translate this into driver speak a little bit, this is the 3 points that we're going to take forward to the next session that we want to concentrate on.

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