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LFS Replay Analyser 1.1
(226 posts, started )
#26 - Davo
1 raf isn't really much fun. 2 or 3 is where it's really happening
Thanks! Probably a stupiud question but what is the "slip ratio"?
The ratio between the speed to the tyre is moving at along the ground, and the rotational velocity it is spinning at. Positive values are essentially wheelspin but two accelerate you need a forward force, which is created by a slip ratio. So there's always a few percent of slip ratio even when the are coping.
Quote from Nick A :Thanks! Probably a stupiud question but what is the "slip ratio"?

It's the relative difference between a wheel's speed and the car speed. ( wheel_speed / car_speed - 1 )

On straights, the slip ratio is close to zero, meaning that wheel and car are moving at the same speed. In corners, the inner and outer tyres turn with a different radius, so there will be more variation.

When the wheel is blocked (e.g. under heavy braking), the ratio goes towards -1. If this occurs several times in a lap, or with more than one wheel, you should lower the brake force, or tweak the brake balance.

A slip ratio of > 0 means that the wheel is spinning. If you see it at corner exit, you're pressing the throttle too early. It might be solved by adapting the setup for more grip (tyre pressure, diff settings, or downforce).

EDIT: Bob beat me to it.
Thanks for the replies. From what you said I take it that the comparison is made between the rotational wheel speed and the C of G of the car, rather than the speed calculated at the location of the wheels (to take into account the extra/reduced speed the wheels travel in relation to the ground due to the cornering radius)?
#31 - JTbo
Tire grips best when it slides, just a bit sliding is enough. Peak slip angle is where this magical best grip point is, often around 7-10 degrees of lateral slip.
#32 - Davo
I've been doing more analysing than driving because of this tool! baah its drivign me insnae how bad I drive
Quote from Nick A :From what you said I take it that the comparison is made between the rotational wheel speed and the C of G of the car, rather than the speed calculated at the location of the wheels (to take into account the extra/reduced speed the wheels travel in relation to the ground due to the cornering radius)?

Yes. You could correct the calculation by taking the cornering radius into account, but maybe you should also correct for the angle and rotational speed of the car body. It's getting pretty complicated then...
Quote from Davo :I've been doing more analysing than driving because of this tool! baah its drivign me insnae how bad I drive

Thanks for the compliment
I got 2 feature requests.

It would be nice to have the values of the Y shown in the status bar. So for example when I compare 2 speed graph's, I'd like to hover the crosshair over the line, and know exactly how fast my car was going.
Right now all I can tell from the graphs is that I'm slower, but I don't know by how much.

Second request would be selecting multiple wheels. Right now I can only select 1 wheel. If you would replace the wheel comboBox with a listBox, users could select multiple selections with the control key.
Maybe it's possible to do the same with the left most comboBox, so people can select both the throttle and brake graphs.

I do love this app, so keep up the good work
Feature request.

A numerical tooltip that gives you X and Y figures as you move over the graph.

And a zoomable track map

And the driving line view that moves with the cursor.
Quote from mikey_G :It would be nice to have the values of the Y shown in the status bar. So for example when I compare 2 speed graph's, I'd like to hover the crosshair over the line, and know exactly how fast my car was going. Right now all I can tell from the graphs is that I'm slower, but I don't know by how much.

If you want to know the speed difference, you can set the "Difference with" checkbox. With the crosshair and the Y axis, you can read the amount pretty precisely.

Quote : Second request would be selecting multiple wheels. Right now I can only select 1 wheel. If you would replace the wheel comboBox with a listBox, users could select multiple selections with the control key.
Maybe it's possible to do the same with the left most comboBox, so people can select both the throttle and brake graphs.

You could achieve that by opening multiple graphs. And when I add the "presets" feature (see post #14), you'll have an easy way to open them in one go.

Quote from danowat :A numerical tooltip that gives you X and Y figures as you move over the graph.

Quote : And a zoomable track map

I can't see how that would be useful. The driving line pane shows the details of the track, and it's zoomable. The track map is there to give the complete view. If the track map is too small for your taste then just enlarge the pane, the track map scales with it.

Quote : And the driving line view that moves with the cursor.

It moves when you click the mouse in a graph, but I guess you want it to move when the mouse moves? I had a quick try at that. The driving line display becomes very jittery - the redraw function has a hard time keeping up with the mouse. I'll have to optimise the drawing first. And even then the result would be too nervous for my taste. But I could make it an option.
Quote from wsinda :If you want to know the speed difference, you can set the "Difference with" checkbox. With the crosshair and the Y axis, you can read the amount pretty precisely.

That only tells me how the speed in or decreases relative from the other raf file. I was trying to say that i'd like to see the absolute speed if the crosshair hovers over the line. Right now I can't see my top speed for example.
New version
Thx a lot wsinda! Great tool, easy to use and requires almost no expertise (which is great for me :tilt.

Do you plan to implement showing of g-forces in a later version?
Quote from Linsen :Do you plan to implement showing of g-forces in a later version?

Yes, it's high up on my ToDo list.
#41 - Davo
This just keeps getting better and better. Thanks for all your hard work.
looks usefull, hopefully it works for demo's too. im not counting on it anyway
but it uses .raf files from the replay but i can only find .spr files
where to find de raf?
When viewing an SPR, bring up the menu and click "export next lap to RAF". Or Something along those lines.
#44 - Davo
"Output lap data"
#45
This is really clear and easy to use. Thanks.

General question about rafs: is it possible to get them out of a replay without using the output button? I like to compare practice laps in sequence to see where the inconsistencies are occuring and reoccuring. LFS turns that into hard work: run a replay; output raf; stop replay ('cause there's no rewind); fast forward; output lap; repeat ad infinitum - frustrating.

It would be nice to dig into the replay and extract the necessary data in one go....
thanks for the info guys
I've just tested this program and it has a great potential. Clearly simpler to use than F1perfview.
Since I like MoTec's interface, I would like to see histogram and XY plotting features, what F1perview is cruelly lacking of.

nihil:
an example for a 6 lap race
run replay once, output the 1st, 3rd, 5th laps, fast forward between these laps (LFS can't output two consecutive lap in one replay run)
Then replay only one more time to output in the same way the 2nd, 4th and 6th laps.
You need to restart only one time the replay whatever the lap number is 5, 25 or 100, not for each lap (as I think I've understood)
#48
Quote from Bogey Jammer :

nihil:
...
You need to restart only one time the replay whatever the lap number is 5, 25 or 100, not for each lap (as I think I've understood)

Would still be handy just to evade to playback altogether though.
Quote from nihil :Would still be handy just to evade to playback altogether though.

Yes, generating RAF files in LFS is stil a bit clunky. An auto-save feature like I mentioned in post #11 would make things much easier, and would make the learning cycle (drive -> analyse -> adapt -> drive etc.) much faster.
Quote from Bogey Jammer :Since I like MoTec's interface, I would like to see histogram and XY plotting features, what F1perview is cruelly lacking of.

Um, what do you use histogram plots for? I've seen them in MoTec, but couldn't see how they can be useful.

XY plots are already on my list. Or in any case, a traction circle graph is on it. That seems to me the most useful example of an XY plot. (BTW, F1PerfView can do them, but maybe they're too limited for your taste.)

LFS Replay Analyser 1.1
(226 posts, started )

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