Hi Ratzel, Thanks for your answer again. I am doing a pure electrical vehicle simulation, the torque applied to the vehicle is constant when the electric motor start. The process of constant torque will maintain for a time. Can it be concluded that the pacejka model has a different integrator from other tire models if it is due to the integrator? Since reasonable results can be got from pacejka tire model.
在2022年8月22日星期一 UTC+8 00:46:23<[email protected]> 写道： > Hi Stefan, > > your observation is correct. Actually we know this happens only with > handling tires. It is better to make a test with a vehicle with a real > powertrain. Applying a const torque means that the accelerating power > increases with the speed/angular speed which is not realistic. > > We had some discussions about this issue, most likely it is related to > limits in the integrator. There is some work in progress about it, but it > will take a while to get a working solution. > > > stefan schrieb am Sonntag, 21. August 2022 um 13:48:01 UTC+2: > >> Hello Ratzel, >> Thanks for your replying, but I still have some questions about that. >> Recently I tested all the tire models in HMMWV vehicle with the conditoin >> that a constant motor torque was applied to the vehicle. It is true that >> the pacejka tire model is >> less robust than others, but it can give reasonable results when the >> simulation step size 1e-3 was given. The pictures I attached can explain >> what I said(The first picture is for PAC02). The acceleration shouldn't >> increase with time under the constant motor torque. And I also found that >> acceleration was related to the vehicle speed, and acceleration was not >> zero when the vehicle had high speed and engine power was cut off. That is >> obviously wrong according to the vehicle dynamics. >> I want to know why it happened, and it can be described as a bug to some >> extent? or I miss something? >> And I also want to solve the problem with your guys and I am checking the >> codes of tire parts in chrono. I would be very appreciated if you have more >> advice for me. >> Thanks again! >> [image: PAC021MS.png][image: PAC891MS.png][image: PACEJKA1MS.png] >> Stefan >> >> 在2022年8月21日星期日 UTC+8 16:28:13<[email protected]> 写道： >> >>> Hi Stefan, >>> >>> the Pacejka tire model in chrono is just outdated. While it is nearly >>> feature complete, it lacks stability. Another problem is the data input >>> routines. It pretends to read tiem orbit files (Adams/Car), but expects the >>> data entries to be in a certain order. It is very likely that nonsense >>> input is read from a valid Adams/Car tire file, as long as you don't >>> reorder the data lines, I guess nobody is eager to do that. >>> >>> If you want to use a Pacejka tire model in chrono, use Pac02. Pac02 >>> hasn't all features possible, but it works and doesn't crash chrono vehicle >>> simulations. For a benchmark project we needed a Pacejka89 (Adams/Car) >>> model. This model has a very clear implementation structure, this structure >>> was the also taken for Pac02. The slip definitons differ of course, as do >>> the formulae. >>> >>> Pac02 and Pac89 are comparable in simulation accuracy. Pac02 can be >>> easily rescaled to different tire load levels due to its skaling factors, >>> so it is more flexible to use. >>> >>> stefan schrieb am Dienstag, 16. August 2022 um 10:43:57 UTC+2: >>> >>>> Hello, >>>> >>>> The pacjka tire models expressed in the manual >>>> <https://api.projectchrono.org/wheeled_tire.html> are Pac89 and >>>> Pac02, But I found pacjak tire model in HMMWV vehicle, and the simulation >>>> results derived from Pac02 and Pacjka model are obviously different, I >>>> don't know which model is better for vehicle simulation and which derived >>>> simulation result is closer to the real one. Otherwise, could you tell me >>>> the difference between Pacjka model and Pac02 model from the >>>> implementation >>>> principle. >>>> >>> -- You received this message because you are subscribed to the Google Groups "ProjectChrono" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/projectchrono/099f47e4-67f7-4504-a037-a636d229fa95n%40googlegroups.com.
