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Author: firechief | Created: 2017-09-21 07:50:30
Subject: Mid-season Thoughts on Tire Wear and Strategy
I must say that the racing this year has been considerably more interesting due to the move to Pro mode - less grip hasn't resulted in the expected slower lap times, but errors are punished far more severely than with Semi-pro. A slight mis-calculation that could quickly be corrected in semi-pro will now likely see a car slide off the track, and this has resulted in races which are much less predictable than before.

But that aside, I don't feel the new tire wear feature has lived up to its potential yet. It does allow overtakes after a car's pitted & has cold tires, and also makes the starts interesting, but other than that, tire wear hasn't really played any role at all. Pushing as hard as possible, tires are typically around 80% worn on most road tracks once the fuel tank's empty, hence you change tires when you refuel unless pitting near the very end of the race. To make tires last for 2 pit stops and thus avoid the 16 seconds needed for new tires, cars would need to drive much slower over two entire stints. They'd lose far more than 16 seconds doing this, so this strategy simply isn't an option. The hare wins the race, not the tortoise.

I'd have liked to see a situation where there's more than one "best" strategy for getting to the finish line in the fastest possible time. That way strategies could be split between a robot's drivers, or the author could choose just one strat for both cars if they believe its optimal ... or potentially a robot could dynamically change strategies according to the circumstances, especially if a car has had to pit out of sequence due to damage.

To do this, my feeling is that tires need to wear faster, such that you can't use a full tank of fuel on the one set of tires unless you slow down, and that the pit delay for fitting new tires needs to be longer. The robot author can then choose between high speed laps with more pit stops, or slower laps but fewer visits to the pits. This could mix races up a lot more, with cars on different strategies ending up out of position and potential for slower cars getting ahead of faster ones and holding them up (depending on the track).

I believe it was originally Bernhard's intention that different strategies be possible - I think he assumed that slow cars with less wear would be able to stay out longer than faster cars that burn through their treads, get ahead of them & then hold them up, with another assumption that a car lapping 5 seconds a lap slower would be able to hold faster cars behind. None of this has proved to be true in practice.

Of course there's other elements of tire wear that haven't yet been added to the model in TORCS, such as flat spots and blistering, but until they're in the game we don't know what effect they may have on strategy. There was also the idea of different tire compounds being available, a soft and a hard for example, along with dynamically changing track conditions - but I don't know what the plans are there.

Obviously the rest of this season will be run with the 1.3.8 beta, and that's fine. But I do think it'd be helpful if we all discussed this in order to give Bernhard feedback on how well the model's worked over the course of the 2017 championship and what could be done to improve it for 2018.

So, I've rambled on for long enough. What are your views on this?
Last Edited: 2017-09-21 11:39:09 by firechief
    Author: dummy | Created: 2017-09-21 09:52:20
    Subject: Re: Mid-season Thoughts on Tire Wear and Strategy
    Yes, the tire wear feature has indeed had very little effects on the predictability of the races. It surely wasn't intended to be like this.
    I think it will be difficult to bring more unpredictability into the races unless we get more participants, especially Crazy Ivans, or add more speed influencing factors with complicated models.

    On the other hand, one of our biggest problems is the lack of racers. And if we make it more and more complicated, who will want to spend his free time on this? I already wonder, why I have to teach the same tracks to my bot every year again. Wouldn't it be nice, if I could take last years setup and the lap time will be pretty much the same? I could spend more time on improving other parts of it ;)
    Last Edited: 2017-09-21 09:52:20 by dummy
    Author: fa1 | Created: 2017-09-21 15:33:37
    Subject: Re: Mid-season Thoughts on Tire Wear and Strategy
    Actually, as newcomers we expected that the new tire model would make it easier to get close to the established teams. However that did not happen because you all were able to easily absorb the change to pro and the new tire model without any visible difficulty ... generating even new track records!

    We also agree that there is no visible impact on race strategy and we expected more variations like undercut strategies to emerge, which is not happening. Instead, behaviour in traffic is key and dominates everything, where clearly established teams have an edge.

    Therefore strengthening the influence of the tires onto the race strategy would be welcome. This would amplify the endurance character of races where strategic choices have more weight vs brute force racing.
    Last Edited: 2017-09-21 15:33:37 by fa1
      Author: firechief | Created: 2017-09-21 17:36:23
      Subject: Re: Mid-season Thoughts on Tire Wear and Strategy
      Regarding the undercut tactic, that will only work if tires have a drop-off in performance (grip levels) as they age AND if new tires are pre-warmed rather than the ambient temperature. That basically allows a car to pit and immediately set fast times on the new tires, while another car that stays out will be a little slower, and the longer it stays out the more time it loses to the car that pitted.

      The current TORCS tire model (no grip loss due to tire age, and cold tires when fitted) means undercut simply isn't available as a tactic, which is a pity. We'll just have to see which way Bernhard wants to go with this.
      Last Edited: 2017-09-21 17:36:23 by firechief
    Author: wdbee | Created: 2017-09-21 20:07:54
    Subject: Re: Mid-season Thoughts on Tire Wear and Strategy
    > I'd have liked to see a situation where there's more than one "best" strategy for getting to the finish line in the fastest possible time.

    > But I do think it'd be helpful if we all discussed this in order to give Bernhard feedback on how well the model's worked over the course of the 2017 championship and what could be done to improve it for 2018.

    +1 from me

    BTW: There are other bugs in the current TORCS version as well:

    e.g.
    -The extrapolation of the race time total for excluded cars that results in cars driving only some fast laps and be in front of others driving fast the hole race but including all the traffic, pit stops ... :(

    - Number of pit stops displayed > 150 but done only 3

    - Different conditions for first driver in qualifying

    - The unbalanced fuelconsume that allows different strategies for some cars only while others have to fill up allways as much as possible if they want to drive as fast as the opponents can

    - Dirt-3 missing in track list of TRB (to display the statistics, who was when fastest in qualifying)

    Wolf-Dieter
    Last Edited: 2017-09-21 20:11:51 by wdbee
      Author: berniw | Created: 2017-09-23 03:38:14
      Subject: Re: Mid-season Thoughts on Tire Wear and Strategy
      Hi all

      @extrapolation: I agree that it needs 2 improvments, namely: the classification criteria must consider out of fuel cars correctly, and it should just apply in the range of +/-1 lap (see initial idea in the code). This should do the trick.

      @Pit stops 150: Sounds like a bug, but not like a critical one, how do I reproduce it? I am aware of some classification logic issues in the pit code regarding penalties, but I do not know if it this applies to this case (probably not). Short: we should fix it.

      @Different conditions: Depends on the reason, but I think fixing it would be good

      @Balance: Ongoing process, I just want to go there in little steps to not create the "uebercar" accidentally.

      @Dirt-3 missing: ? I can see it, how do I reproduce this?

      Additional tasks:
      - Fix for pit lane (Hidden Valley)
      - Adopt trb for new php versions
      - And just the still open and ongoing stuff for final 1.3.8 and beyond:-)

      Kind regards

      Bernhard
      Last Edited: 2017-09-23 03:41:02 by berniw
        Author: wdbee | Created: 2017-09-23 16:37:56
        Subject: Re: Mid-season Thoughts on Tire Wear and Strategy
        OK, my fault, I was searching D(irt) between C and E, not after W ;)
        Last Edited: 2017-09-23 16:37:56 by wdbee
    Author: berniw | Created: 2017-09-23 03:24:06
    Subject: Re: Mid-season Thoughts on Tire Wear and Strategy
    Hi all

    Not back at home yet, but quickly commenting from abroad:

    @Andrew: Regarding wear and pit stop times, there are "race xml" parameters regarding that (see changelog, xmls or source), so with the parameter xml download feature of the trb we can adjust this however we like it for trb races. Maybe you guys already start doing some experiments, such that you can suggest then the desired values for the next season (tire wear factor, tire change time, ...).

    @Wolf-Dieter: I agree about some of the issues, those will get fixed soon (after I come back home I have still 7 weeks off and plan to use 4 hours per day to work on TORCS and TORCS-related stuff).

    Btw. it is really cool to see how you guys care:-)

    Kind regards

    Bernhard
    Last Edited: 2017-09-23 03:24:06 by berniw
      Author: firechief | Created: 2017-09-23 10:45:10
      Subject: Re: Mid-season Thoughts on Tire Wear and Strategy
      Hi Bernhard,

      Yes we should definitely experiment - didn't realise it was as easy as changing parameters in an xml file. I do think it should be preparation for next year though, with lots of discussion to get everyone's agreement on settings which should generate the most interesting races.

      And of course we care - I'm still aggrieved that the berniw bot is missing this year :\

      cheers
      Andrew
      Last Edited: 2017-09-23 10:45:10 by firechief
      Author: wdbee | Created: 2017-09-23 16:34:50
      Subject: Re: Mid-season Thoughts on Tire Wear and Strategy
      Hi Bernhard,

      hope you enyoy your trip. Being back let me know what I can do to help you to fix the bugs.

      Have a nice time

      Wolf-Dieter




      Last Edited: 2017-09-23 16:34:50 by wdbee