Hi everyone, Before making this thread, I reached out to several experienced modders in our community as well as 397/MSG staff to gather their insights and advice. Understandably, they're all very busy with their own commitments and projects. So, I've decided to create this central thread for all of us to hopefully communicate and contribute our knowledge and experiences. The goal of this thread is essentially to delve into the physics parameters necessary to achieve consistent AI (which is what I believe plays a significant role in the reduction of oversteer and understeer for them). In essence, I am hoping by pooling our collective expertise, we can hopefully develop a understanding and possibly a set of universal parameters that can be applied (should it work that way). I've noticed, as I’m sure many of you have, that a lot of the rFactor 2 modded content falls short due to the AI, and if we can retrospectively apply these fixes, it would restore a lot of life for the single-player modding scene. What I know so far: - When observing the GTE/GT3 official content, the AI do not suffer with understeer or oversteer issues (in the sense that they do not turn the wheel 360 degrees for small corners). This ultimately means that they're more consistent and do not suffer time loss. When I approached Coutie at Studio 397 to see how this is achieved, I was advised that it is largely down to the physics of the car but at this stage, it is unclear what parameters play a significant role for the AI. Apparently the physics guy may release a blog, but given how busy they are with LMU, I am not sure if this will ever materialise -I reached out to Nick9320 regarding his workshop content that was recently released (noticeably the Ferrari and Porsche), both of which are insanely well optimized for the AI. No understeer or oversteer issues, very consistent, and he also implied it was largely physics related as well - I am well aware that adjustments to the .JSON file can rectify this to some extent, as well as adjustments to the .TBC for the relevant car, but again, I think the nitty gritty of the physics parameters is largely where the consistency comes from, and it is trying to understand where that is. Here is an example of poor AI (it is to the extreme, but observe the wheel rotation). In this example, it causes the car to slide but in other mods, they may not suffer as badly as this, but still suffer significant timeloss as result of the understeer /oversteer behavior. I would appreciate any guidance on this.
For a while I helped with the physics of ASR cars and I couldn't find the solution to this problem. It looks like something is in the suspension but I don't know for sure.
AIGripMult in the TBC is the easiest way to tune the AI's balance. If understeer is a problem, increase the front tire AIGripMult and/or decrease the rear tire AIGripMult. I will caution against using more than 1.1 for AIGripMult as that means the AI always stays on the track while the player car gets shunted. If you find it necessary to go above 1.1 for AIGripMult, then it's probably time to redesign the TBC.
@Pales Can you link a Car with that you have extreme Understeering of the AI? I want to test something. There can be a lot of Reasons for Under- and Oversteering, so there is no "do this and that and the Problem is solved". A Solution, that improves it for one Car, must not improve it for another Car too.
I know you say AI but this sim is real time physics for AI yes ? I think the low rolling resistance of engine could have bearing on some issues will never be solved till that is. This excessive rolling effect causes push just as it would if you could simulate it in a real car..... it is like putting car in neutral at bend, well not that extreme but you get my point. You say black art, no more so then this behaviour which I have never seen talked about, like ever.
Are you able to elaborate a bit more on what "redesign the TBC" would mean. I've had cars where no matter what I adjust, I can only get them to behave properly by exceeding 1.1. The worst I've had needed 1.18 on the front and I tried everything on that car but if there are other parameters in the TBC that could be changed, that would be great to know. Most cars I can solve understeer by adjusting the third value of AIPerfUsage in the HDV file and AIGripMult in the TBC file. I start by reducing the AIPerfUsage first and then if they corner too slow I bump up AIGrip Mult. It's a bit of a balancing act between the two but it's possible to get them both to the point where the AI are cornering at the same speed as the player without understeer. I think default suspension setup can also help combat AI understeer by having a more oversteer type setup. That understeering in the Lambo in Post 1 was introduced with v1133. s397 reduced the AIPerfUsage values in the player.json file to combat this on their cars but that caused the AI to corner too slow compared to the player. If you increase these values, the GT3 AI cars do in fact understeer, but not as drastically as the one above.
Thanks for sharing this information! Hi Chris. In the example that I used for this video, I believe it was the Simtek GT3 World Series. I completely understand that a universal set of parameters may not work for each car, but really the whole thread is about understanding what needs changing https://steamcommunity.com/sharedfiles/filedetails/?id=809355570 Interestingly, in a lot of the mods that I see with very consistent AI, I check the .HDV and the all of these values are negative to indicate that it uses the player.json file. My understanding is that only positive values override it, otherwise the player.json file is used. I have even had a look at snippet of a HDV file for the official cars, and I can confirm all of the parameters for the AI are negative in that area. This, again, suggests to me that the .TBC and physics parameters are really what is important to getting a stable ai car, but I welcome anyone to challenge that. Love all the discussion we're generating already!
You only "believe"? Please give me a Link to a Car where you are sure, that it's AI has massive Understeering.
I have had an opportunity to check and it is most definitely the GT3 World Series (specifically the Lamborghini Huracan GT3) that I used in the example video. Within dev mode yesterday, I was able to adjust the .TBC to make it more reliable with less understeer and oversteer, and I also adjusted various physics parameters which made quite a significant change as well as the wing, however, I cannot imagine that they're compromising the entire physics of the car to cater towards the AI, so I do wonder what the secret is. Unfortunately it is not available to download separately, it is via the steam link above due to it being bundled in a pack.
@Pales OK, i will check what i want to check at the Huracan then. But what i don't understand, is your "so i do wonder what the secret is". From my Point of View, there is no "Secret". If you setup the HDV in a Way that it represents the driving Behaviour of the real Car, you've made a good Job and the AI should drive good too. Of course there still can be Things like e.g. tbc Values that are not properly set. And it needs "some" test driving to equalize the tbc (AI) to the tgm (human Driver) Tires. You've said that you had the Opportunity to see the AI Settings of a DLC HDV and they were all set to -1 (deactivated) and you also said that the DLC AI drives well. So you can assume that the HDV of these Cars is well done. I know that it is one of the hardest Parts in Creating Cars, to build realistic Physics, especially if you don't have Data and nobody who has driven the real Car and will test drive for you. When we did make the GP3 and F3 Mods, we had Contact to a real Team (thanks to @Slow Motion), where we've got a lot of Data and Feedback from the Team Engineer and the Drivers, that drove our Car in the Game, which was great. But you normally don't have that, so that it's even more difficult to set up Car in a close to Reality Way.
It is probably my lack of knowledge which leads me to come to these sorts of conclusions, but thanks to likes of yourself and others who are sharing such information, I am learning more and more each day. It does make sense that if the car physics are well thought out, then technically providing the .TBC is configured well and the .HDV then the AI should be consistent. I guess my next question is, if the physics are well thought out and correct, what sort of documentation do you follow to ensure the .TBC is good enough for the AI? I could just look to copy the .TBC values from other mods and apply this, and that is what I have done in the past to improve consistency for cars that were otherwise unstable, but it would be good to get an insight into how people start this process for the AI.
@Pales As i've said in our private Conversation (i guess ), i normally don't care much for the AI and so Marco (@Slow Motion) was always doing such AI related Things. If ever, i only took care for the Tire Sizes, to get no Speed Differences between AI and Player. Maybe you contact Marco directly, to get some advanced Info. But i did check what i wanted to check now and it is a possible Problem too. Of course, i don't know the Code, how the Steering gets handled in Game. But i know, that it is almost impossible to set the Steer Lock Angle properly in the Physics Spreadsheet, especially in older Versions. So i've made a "Tool" some Years ago, with that i can check the Steer Lock Angle in Game. In this Case, with the Symtek GT3 Huracan, there is a Difference of 5 Degrees, between the set Value of 15° in the HDV (SteerLockRange=(15,0,5)) and the Angle in Game (10°). As said, i don't know how the Game Code handles the Steering, but i would recommend to set it up in that Way, that the Angle in the HDV and the Angle in Game are the same.
I have a Steer Lock Tool in my Online Tools, with that you can adjust the Steer Lock Angle. But because we can not trust the Angles that are set in the HDV, you would need my "Tool" from the above Screenshots, to check the Modifications, because without a trustable basic Value from the HDV, from that my Script takes the Values, i can not display the Changes of the Angle in my Tool.
The SLIPCURVEs and DryLatLong/WetLatLong are other possible areas, but I haven't tinkered with them in ages so I'm supposing they affect AI. Would be nice if someone could confirm... I'm not going to have time to test in the near future. Absolutely agree!
@Pales In my above Post, i forgot to say, that the 10° Steer Lock Angle in Game, that the Huracan has, is not so big. So it could be (always judged under the Fact, that i don't know the Games Code for the Steering), that Understeering appears, when a Turn is tight and the Steering Lock Angle is too low, to take the Turn with the "normal" Speed.
Thanks again, mate. I have to say, I have been going back as far as 2015 for modding related questions (trying to expand my knowledge as much as I can without having to bother anyone), and I always see your historical replies. Very insightful, and it's good to see after all these years you're still here and contributing to the community!
@Pales At least i try to continue Contributing. In between have been a few Years, where i was banned from the Forum, so that i couldn't do it.
