How do F1 Power Units Know When To Harvest?

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
peanutaxis
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How do F1 Power Units Know When To Harvest?

Post by peanutaxis » Mon May 01, 2017 10:45 am

I don't see the drivers pressing buttons, so......how do the engines know when to harvest and charge batteries down the straight? Surely it can't be speed because that would compromise you if you are ever slow down the straight for traffic or something. So .... it must be GPS?

George-Jung
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Re: How do F1 Power Units Know When To Harvest?

Post by George-Jung » Mon May 01, 2017 8:55 pm

Probably they can program it in the software? So it knows due to throttle and brake in put where the car is on the circuit?

Jolle
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Re: How do F1 Power Units Know When To Harvest?

Post by Jolle » Mon May 01, 2017 9:13 pm

George-Jung wrote:
Mon May 01, 2017 8:55 pm
Probably they can program it in the software? So it knows due to throttle and brake in put where the car is on the circuit?
and GPS....

Frafer
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Re: How do F1 Power Units Know When To Harvest?

Post by Frafer » Mon May 01, 2017 9:37 pm

it's the kind of topic that's a bit too complicated in order to be meaningful assessed here. Let's say there are some software that handle the PU in every aspects, evaluating tons of variables, but for the sake of simplicity we'd say that the K charges the battery during braking, and so does the H (sort of); and that energy is deployed somehow (directly or not) to the crank in the first part of every straight; at the moments before braking a lot of things can happen, depending on mapping.
But still, we are miles behind a serious understanding of how things actually work

(of course gps position is one variable, like throttle pedal position, brake pedal position, mapping, energy managment settings, fuel managment ecc ecc)
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rekoildale
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Re: How do F1 Power Units Know When To Harvest?

Post by rekoildale » Tue May 02, 2017 5:17 am

I have heard or read that there ar no rear brakes they use the generator to slow the rear of the car and that was the initial problems with corner balance in the beginning of this era. But as for harvesting i think it would be all software as the parameters needed are all captured in microseconds. The rear harvest light occasionally has flashed on the straight and the cars nearly stop and they said at the time it was a malfunction of the software.

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Sevach
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Re: How do F1 Power Units Know When To Harvest?

Post by Sevach » Tue May 02, 2017 6:22 am

They can program it according to speed, which gear the car is in, and in some cases distance based(not "wasting" power between the 2 Lesmos for example).

Normally you get small doses of power in the lower gears, full in the middle gears and it goes into harvesting as you approach top speed(race mode we are talking here).

wuzak
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Re: How do F1 Power Units Know When To Harvest?

Post by wuzak » Tue May 02, 2017 6:30 am

rekoildale wrote:
Tue May 02, 2017 5:17 am
I have heard or read that there ar no rear brakes they use the generator to slow the rear of the car and that was the initial problems with corner balance in the beginning of this era. But as for harvesting i think it would be all software as the parameters needed are all captured in microseconds. The rear harvest light occasionally has flashed on the straight and the cars nearly stop and they said at the time it was a malfunction of the software.

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As the rear braking energy recovery is restricted to 120kW it would be impractical to do without hydraulic brakes.

The rear brakes are smaller than they were up to 2013 because of the electronic assistance, and they fail quickly if the MGUK fails.

J.A.W.
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Re: How do F1 Power Units Know When To Harvest?

Post by J.A.W. » Tue May 02, 2017 6:48 am

Here O.P., this is all you need to know, subject-wise..

https://www.youtube.com/watch?v=QCRAUKWKKlo
Dr Everett V. Scott sez.. " I happen to know a great deal about a lot of things."

gruntguru
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Re: How do F1 Power Units Know When To Harvest?

Post by gruntguru » Tue May 02, 2017 7:02 am

At the most basic level the control algorithms could be made fairly simple:

MGUH. The engine management system demands a compressor speed setting based on engine speed (and throttle).
Under heavy engine load the MGUH will have to brake the turbocharger (harvest energy) to maintain that speed.
Under light engine load, the MGUH will have to motor the turbocharger (draw energy from the ES).

MGUK. The engine management computer adds power to the MGUK according to throttle setting starting at say 95% throttle and increasing to max (120 kW) at 100% throttle.
The engine management computer subtracts power (harvests) from the MGUK according to brake pedal position starting at 0% throttle and increasing to max (120 kW) at say 5% brake pedal position.

It is also likely that regenerative braking is to some extent linked to throttle position so that the lowest few percent of throttle operation actually controls harvest from the MGUK producing an effect similar to engine braking.

The above are very simple algorithms/tuning-tools - simpler than those already used for engine mapping.

EDIT. Not suggesting for a minute that the actual algorithms used are anywhere near this simple.
Last edited by gruntguru on Wed May 03, 2017 5:00 am, edited 1 time in total.
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henry
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Re: How do F1 Power Units Know When To Harvest?

Post by henry » Tue May 02, 2017 11:36 pm

I think there is also a mode in which the torque demand at low engine speed/partial throttle is met by running the ICE against the MGU-K and so charging the ES.

Given that the ICE will be more efficient at higher torque output the overall PU efficiency will be higher if the round trip losses, MGU-K to ES -and back to MGU-K, are lower than the difference in ICE efficiencies. This calculation would also need to include the MGU-H which might use less charge or contribute depending on the operating point.

However. The goal is not PU efficiency but lap time reduction. So in some circumstances there is probably a case to be made to burn additional fuel at times when low power is demanded, in the twisty bits, in order to have longer MGU-K deployment on the faster bits. This would mean that the charging strategy would be circuit dependant, relying on simulations to establish a State of Charge versus position in lap, providing a target for the ES algorithms. Whether this is done or how they might establish position in lap I don't know.

I recall seeing a report from Andy Cowell that the Mercedes ES algorithms are adaptive so that if something changes, say wind direction or tyre performance, the deployment will change over the course of a few laps. It was suggested that Hamilton's problem in Baku would have righted itself over the course of the race.

I would hazard a guess that even within the teams few people actually know concepts behind the strategies let alone the detail of how they are implemented.

PlatinumZealot
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Re: How do F1 Power Units Know When To Harvest?

Post by PlatinumZealot » Fri May 05, 2017 5:27 am

It is set by algorith then manually programmed. Usually the human programming is needed because real life running is always different from simulated.

honda for example still spend considerable timing manually tweaking the ERS strategy for each race.

The brakes is also the same thing. note how Haas needs like two weekends to fine tune the brakes.

The systems are so transtransient that the computer just doesnt know the big picture.. Even if you use multiple cascaded control loops the computer still does not know the big picture. You have to feed it the "feed forward" part and it will do the rest.
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wuzak
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Re: How do F1 Power Units Know When To Harvest?

Post by wuzak » Fri May 05, 2017 6:35 am

How do F1 Power Units Know When To Harvest?

Black magic, obviously.

henry
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Re: How do F1 Power Units Know When To Harvest?

Post by henry » Fri May 05, 2017 8:59 am

Further to my suggestion above that one of the things that might be controlled is state of charge(SOC)versus track position. I have been thinking about what might be involved in relation to Andy Cowell's comment about wind direction and the comments from the Honda managers that the ERS strategy needs to be tuned to the car.

On wind direction I think this can be inferred from the air speed (pitot) and the road speed, (wheel speed or ground laser). You would probably want to use most deployment in the tailwind direction, so knowing this would allow the SOC to be modified on the fly to prioritise downwind straights, if the wind direction or strength changed.

On car parameters if you know grip level, a combination of tyre, aero and suspension, you can estimate how early on a straight you can start deployment and when you might expect to be able to charge. This will be dependant on aero configuration , tyres fitted, track evolution, rubbering in, and the aforementioned wind direction. Once again this would modify the SOC vs track position map, if there is more grip discharge earlier and de-rate (switch off MGU-K) earlier.

I would expect there to be monitoring of fuel use vs track position also. Again with a target map and a bunch of measured parameters. Outputs could be dash readings, lift and coast beeps, shift point settings and probably others.

Each strategy set on the steering wheel will probably have different maps, and they may or may not, cross populate.

Of course it may be nothing like this at all. And I still have no idea about the answer to the OP's original question, how does it know where it is on the track.

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Re: How do F1 Power Units Know When To Harvest?

Post by MrPotatoHead » Thu May 18, 2017 6:31 pm

A combination of Driver Mode Selection which then selects software / time / location / parameter driven harvesting.
But it is clear that the driver is often selecting the mode.

90% of the settings will be determined on the simulators before the team gets to the track.



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