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Endogenise optimal speed per leg


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Description:  ABRP should calculate the optimum speed for each segment.

Use Case: Currently, ABRP uses the speed limits of the road or live traffic and the maximum speed as set by the user. Whilst ABRP tries to optimise the time, it only drops the speed when this is necessary to reach the next charger.

Example with the Model 3: https://abetterrouteplanner.com/?plan_uuid=e58b6959-18d8-43e4-b82e-f8c9b22b6153

I set a max speed of 198 km/h. This results in a time of 9 hours and 17 minutes.  If you drop the max speed to 165 km/h, time taken is only 9 hours and 8 minutes.

Same route with the Ampera-e: https://abetterrouteplanner.com/?plan_uuid=85feb0d7-6eb6-456d-9a74-a330c6a2f74e

With a max speed of 160 km/h, this takes 12 hours and 38 minutes. At 130 km/h, it's only 12 hours and 19 minutes.

These times could probably be optimised further by having different speeds on each segment.

Whilst optimising this globally would be the best solution it is probably tricky as this introduces are many degrees of freedom. There could be a "light" optimisation by taking the charging locations as given and only varying SoC to charge to, and speed. You could then display an "optimum speed" at all times while navigating.

Example: based on the charging curve of the Ioniq 28 kWh, it is always never good to charge to more than 83% as the charging power drops a lot above that (from ~48 kW to 22 kW). ABRP happily charges to a higher amount and then drives at full speed (e.g. 130 km/h as set in the default, which is close to optimal in general) if that is enough to reach the next stop.  However, it is almost always better to charge to 83% only and drive a bit slower than 130 km/h.

What do you think?

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  • 2 months later...

I agree.

I learned of ABRP just few days ago.

When I checked the suggested routes for the first time yesterday, I was really surprised it didn't suggest any speed for any of the trip leg to optimise the total trip time. IMHO this is a MUST TO HAVE feature.

From my research and own calculations (spreedsheets and Python scripts), some cars do have optimum at very high speed (135km/h), if they have access to fast chargers (like 100kW), but when using 50kW, this drops significantly to about 110km/h. Obviously the exact values also depend on exact charging curves, elevation changes, ambient temperature, and other conditions, all of which can be mostly modeled too. The others like speed changes, overtaking, curves, wind, are a bit harder, but on average can be ignored IMHO.

For short trips and city driving this optimisations and suggestions are mostly irrelevant, but for longer trips, it definitively is worth improving your effective trip speed. It can be 10-15% in the total time on a long trip.

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