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Data Analysis Fundamentals: Step 5: Analyse Driver Performance

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Step 5: Analyse Driver Performance

13.40

00:00 - So the next step is to go through and look at the data from a performance perspective.
00:03 Here we're going to be going through and finding why there is such a big difference in lap times between these two drivers.
00:08 So over here on my laptop screen I've got a slightly different layout configuration to what I had before.
00:12 This is more what I'd be looking at from a performance perspective.
00:15 So I've got here the lateral G force, the longitudinal G force, the two speed traces and also a time delta plot here.
00:22 So with this information even though it's relatively basic, we can actually learn quite a lot about the way the cars are being driven based just on looking at this really simple data.
00:30 I've also got a track map showing up here so you can see as I move throughout the laps you can see that those little cursors are showing me for each one of the, the position of each one of the cars on track which can be nice just to add a little bit of context, particularly if you're not really familiar with that particular track and the data that comes with it.
00:49 After a while, what I find is I don't generally need to use the track map because once I'm used to seeing the format of the data, because this sort of fingerprint or this profile you get of the speed trace, you tend to start learning which corners are showing up as which parts of the speed trace without having to use the track map but it is a good useful thing to start with.
01:08 You can see down the left hand side here, we've got the different channels that I have got turned on and off as far as being selected.
01:14 If you want to add any in here, all you need to do is go through, let's say if we wanted to look at the external voltage, I could just click that on and off here, same with the vertical acceleration.
01:24 I can click that on and off here and it just adds it in and out of that plot so it's quite a simple and intuitive way to use it.
01:30 You can see as well as I move the cursor throughout the lap, these values in this column here are updating to show us the actual real value at that position of the cursor.
01:38 The other thing to keep in mind regardless of which data analysis system you're using is whether we're using a time or a distance scale along the X axis.
01:47 So we've got these different context controls up here but the main one I want to point out here is whether we're by time or distance.
01:53 So you can see if I click here, the X axis down the bottom here is going to a time scale but I want to make sure that I am sitting on a distance mode as well.
02:01 We've also got the ability to change how the different data is shown on that time distance plot, generally I'm going to have them segmented like this.
02:11 You have got some flexibility to overlay them as required but I find using the overlay function to usually be a bit overwhelming and not actually that useful.
02:19 So most of the time I've got, certainly from a beginner's perspective, you'll probably find it easier to have them segmented in their own section of the time/distance plot.
02:27 As we talked about in the course, one of the big tools that's really useful for understanding differences in performance on track is looking at the time variance or that time delta plot.
02:36 So down the bottom here, that's what we're looking at.
02:39 So we've got blue time as the reference, so you can see up here, that's the 1:49.496 vs a 1:53.046 so quite a big difference in lap time between those two and we can see how that lap time difference evolves as we move throughout this lap.
02:55 You can see how that time variance is changing.
02:57 So straight away I see a really big time loss from this section of track all the way up through to here and we can see based on this big jump in the time variance here, and we see that really clearly in the speed trace here, that's going to be one part we're going to be looking into.
03:13 Another big jump is this one here, in fact this is a particularly steep jump where we're losing a lot of time all in one spot.
03:19 It's really that gradient of that time/delta plot that's telling us the importance of each lost point on track.
03:26 So certainly that's another one I'll be looking at.
03:29 This section here as well, where we've got another big up slope in the time delta is showing us another big place where we're losing time and again we can see that really obviously in the speed trace because we've got this orange data sitting quite a lot lower than the blue reference so we can see pretty clearly what's happening already there straight away.
03:50 You'll see this little spike here in the data, so this is a section on track where because we're losing time on corner entry, but then they've managed to gain it on corner exit.
04:00 In this particular case I don't think this is a genuine case, you can see how early they've braked here compared to the reference but I think it's more than the other reference that we're using, the blue data has had quite a poor run out of that corner so I'm not going to read too much into what's going on here in this part of the track.
04:17 So let's start digging into the data and let's see what we see as for the reasons for this.
04:20 So straight away a couple of the controls we're going to be starting to use are the up and down arrows, I'm just using here without a mouse on my laptop.
04:29 So if I just press up and down on there and I can also, one of the other ways I can pan across is just by dragging that distance scale along the bottom just to focus in on where I want to look at.
04:41 So straight away we see quite a big difference in the way the car's being driven through here.
04:46 There's a big difference both in the braking points and that's actually something we should talk about before we get into the initial part of this loss is you see the orange driver here has got this big gradual slope as they start slowing the car down.
05:00 What we generally want to see in the speed trace, it's quite an abrupt end so when it comes, we see the car accelerating like this.
05:06 We want to see the speed trace nose over relatively quickly with quite a sharp edge between them.
05:11 If we've got a really rounded edge like that, that's essentially telling us the driver's been quite sloppy between, it means they're getting off the accelerator slowly and then it's taking a while to get to the brake.
05:20 Ideally we want them to be getting abruptly or relatively abruptly off the throttle, in this part of the track anyway we want them to be getting relatively abruptly off the throttle and straight onto the brake pedal.
05:30 So this sort of sloppy transition from accelerator to brake here is giving us this really, this sort of rounded shape curve which is straight away something we want to get rid of.
05:39 We can also see how long it's taking the orange driver to build brake pressure at this point.
05:45 What they're actually doing, it's very slowly building brake pressure over this whole section of track.
05:49 So we're going to from 200 metres to roughly 350 metres let's say.
05:53 It's taking us roughly 150 metres until they get to peak brake pressure which is something we want to avoid.
06:01 Generally we want to be getting to peak brake pressure relatively quickly, we want to be getting to the peak, doing most of the stopping early in the stop and bleeding off as we start adding steering lock into the car.
06:11 So that's one technique I'll be talking to the driver about straight away.
06:15 But the real big time loss here is this section as we head through this long section of this corner.
06:22 So we can see on the track map here, essentially there's this really big long carousel where the cars do this big large radius turn and we can see how much speed difference there is between them.
06:33 So essentially all of this time loss through here, which let's have a look at what we've got, we can use the delta function.
06:39 So if we come along here and use the delta function, if I click this point here and click another point, it's showing us in delta there is 1.1 seconds being lost just through that section of track.
06:51 Which in itself is a really big time loss, 1 second in 1 section of track is definitely a big enough time loss that I'd definitely be talking to the drivers, so we can just turn that delta back off and we can zoom out and essentially all of that as we can see that they're just not carrying enough speed through that long carousel, they're over slowing the car on entry and there's a big difference in speed and we can see the current speed that's being, where the cursor's sitting off this section up here, so we've got 123 km/h vs 130 km/h so roughly 7 km/h difference and across that long corner, if we've got roughly that difference between them, that's adding up to over a second of loss just in that section of track.
07:34 We can also see they're taking a lot longer to get back up to speed on entry.
07:38 So they're accelerating and their peak speed as a result before the next braking phase never actually gets anywhere near the reference driver so if we hover those over each other there, we've got 179 km/h plays 165 so again a really big difference in the speed.
07:57 I should also say, the way that these legends work up here.
08:01 We've got, the way AiM does it, they've got some minimums, maximums and averages shown for the amount of data you've got shown on there so that can be a nice little reference as well as the current value of the cursor, that's another place that it's shown as well as being shown over here in this column.
08:16 You'll also notice as I move throughout the lap, as I move the cursor along to a different section, the legend jumps from side to the other just to keep it out of the way of where you're looking which is quite a nice feature.
08:25 So really that's what's going on in that first part of the track through the carousel, they just need to be carrying a lot more speed through there, obviously the car is capable of carrying a lot more speed through that section of track.
08:36 Now let's have a look at this section here where we've got something quite different happening on corner entry.
08:41 Now if we have another look at the time delta.
08:44 So in this section of track we're going from a time delta, we can see up here we're at 1.2 at the moment and we jump right up to 1.7 so we're losing roughly 0.5 second just in this braking zone.
08:54 So if we just zoom out a little bit, I'll just give you a little bit more context about what's happening at this section of the track.
08:58 So as we're coming out of this previous carousel, and we've got this little flip flop section, we go left, right, left and back underneath where the track crosses under itself there.
09:08 And essentially we're losing a whole lot of time just in this short section of track and what we can see in the longitudinal channel in particular, is we've got a big difference in how the brakes are being applied.
09:21 So if we go back to the entry of this section of corners, we can see interestingly the slower driver in orange is actually braking a little bit later than the faster driver but if we look down here in this speed trace we can see the reason for that, it's because they're actually arriving at that corner so much slower so they're not actually braking later in a faster way, they're braking later because they're arriving later at that corner so much slower.
09:44 Now if we look at the reason for why they're losing so much time we can see this big steep loss down here in the time variance is aligning with this big difference in the speed trace here and if we dig in a little bit further, we can see in the longitudinal acceleration, we can see that this driver is having extra stab on the brake pedal here and that's really over slowing that car on the late part of corner entry so we can see the longitudinal acceleration in this section is actually relatively similar, where the drivers are going through that first, they're braking for that first left and then they're adding basically a little second extra stab on the brake pedal to slow the car for that right hand corner but we can see that the slower driver is doing an extra stab on the brake here and that means that they are scrubbing off a whole lot of extra speed for that second point which is ending up costing them extra time so in this position on track we want to be getting our slower driver to, while they might be doing an extra second brake application, we don't want them to be doing any heavy braking in the later part of that braking zone, it's maybe just a little stab and getting back off it, rather than going on and going on harder again which is what they're doing here.
10:48 So that's what that second loss is.
10:50 And then if we go back to the later part of the lap and we dig into what's going on here.
10:55 So this is a section of track, if you look at the cursor and where it is on the track map, this is where we've got another flip flop before we go over a bridge.
11:05 So it's essentially, the idea of this part of the track is to slow the drivers down by forcing them to go through a chicane before they go over the bridge and this is a pretty typical place where you'll have one driver losing quite a lot of time compared to the other because it is quite an intimidating part of the track, it's a very fast section of track and it's right before a big elevation change as well.
11:23 So what we've got here is if we look at the area where we're losing a whole lot of time with the orange driver coming up here, we can see again really clearly in the speed trace, we can see they're just negotiating this whole section a whole lot slower.
11:34 Now this is pretty typical, what we see in the longitudinal acceleration, we can see that they're braking a whole lot earlier, so if we look at how many metres they are braking early, we've got, I'm just going to turn the delta function on here.
11:49 So if we go from there to roughly where the other driver is starting to brake, we've got a delta and we can see up here in the legend in the top right of the display, it's giving us 32 metres of difference between those two points.
12:04 So straight away we can see that the slower driver is braking 30 metres earlier than the faster driver which is a really big difference on track.
12:10 The other thing we see here is actually the shape of the aggression or the amount of brake application they're using is actually quite similar to what the faster driver is using, even the peak magnitude is quite similar, it's just they're doing all of that far too early.
12:24 You can also see here on the corner exit, they're getting off the brake and they're actually getting onto the accelerator, starting their transition back to acceleration earlier but really that's because they've just over slowed the car so much on entry and that's why we're seeing that change in longitudinal acceleration changing so much, they're getting off the brake pedal because they actually realise they've overslowed and that's actually something important to understand, whether you're doing the driving yourself and you're working with the data or you're an engineer working with a driver, often what'll happen, when people overslow the car they'll know instinctively that they have overslowed the car and they will instinctively get back to power or get off the brake pedal because they've realised they've overslowed it but it's just the sort of mental block you've got to get over which is surprisingly difficult to train people out of sometimes.
13:11 So now we've gone through and we've identified those three areas of biggest loss which is typically what you want to be doing, you don't want to be going through and doing a detailed analysis on every single download, you want to limit the number of things you want to try or want to improve in every single run, you don't want to be throwing everything at them at once.