# Finding the Racing Line

Over the last couple of weeks, I’ve been tinkering with various ways of visualising rally stage route data downloaded as KML files. The nature of the routes is such that the linestring can often describe quite a ragged route, made up of it is as a series of concatenated straight line segments.

Whilst looking for ways of smoothing routes — a recommended approach appears to be to use a Savitzky-Golay smoothing filter (?!) — I stumbled across various papers and code repositories relating to racing line optimisation.

One handy repo, `TUMFTM/laptime-simulation`, included a Python code utility for smoothing a circuit given the track centerline retrieved from OpenStreetMap. If you give it a non-closed route as the input linestring, it currently closes it with a staight line connecting the two ends, but it would be useful to try to tweak it to work with non-closed routes (I opened a related issue).

For a general review of approaches to lap time simulation, see Lap time simulation: Comparison of steady state, quasi-static and transient racing car cornering strategies, Blake Siegler, Andrew Deakin & David Crolla, University of Leeds, SAE TECHNICAL paper series, 2000-01-3563. See also Blake Siegler’s PhD thesis, 2002, from the University of Leeds, Lap Time Simulation for Racing Car Design.

Whilst many of the raceline optimisation papers are a bit beyond me (?!), skimming through them and looking at the pictures may provide further ideas about what sorts of thing may be of interest in terms of rally stage route profiles. Where papers have related code repositories, this could also serve as a useful "for real" tutorial guide in how to convert differential equations as described in a paper into differential equations modeled in code.

I’ve added various papers to my reading list, and for want of anywhere else to keep a record of them, thought I’d post them here.

But first, an introduction to corners….

And to racing lines…

For a more detailed look at smoothing trajectories and finding racing lines, albeit in circuit racing, see for example:

It would be interesting to know how circuit racing lines and rally racing lines might differ in terms of optimisation strategy and physics models.

For example, here’s a take on rally racing lines:

And here’s a tutorial on some of the maths (along with a related blog post and PDF):

The associated article also refers to a couple of PhD theses:

Readings wise, this looks like it could be relevant to that: Minimum time vs maximum exit velocity path optimization during cornering, Velenis, E. and Tsiotras, P., 2005 In 2005 IEEE international symposium on industrial electronics (pp. 355-360).

Surface type and surface evolution (i.e. road order effect) as well as weather may also have a significant effect. For example:

Other rally related papers include:

For general techniques for analysing race car open telemetry data:

PS in passing, an interesting looking blog on WRC aero: wrcwings.tech.

PPS Although slightly off topic, fascinating nonetheless, from the Honda R&D website, register and check out their F1 technical review https://www.hondarandd.jp/summary.php?sid=23&lang=en

## Author: Tony Hirst

I'm a Senior Lecturer at The Open University, with an interest in #opendata policy and practice, as well as general web tinkering...

## 2 thoughts on “Finding the Racing Line”

1. E Theodore L Omtzigt says: