Hi, Thank you for your advice, after trying for several days, I succeed in using co-simulation, and it took only 10 minutes every one simulation. I have another question now, as I said before, I am going to use reinforcement learning with chrono. I think of using openAI and I also found projectchrono <https://github.com/projectchrono>/*gym-chrono <https://github.com/projectchrono/gym-chrono>*. However, I don't know if I can realize what I have done with *PyChrono*, because the Chrono::Engine Python module does not cover all the features of the C++ API. Meanwhile, in Project Chrono: Install the PYTHON module <https://api.projectchrono.org/development/module_python_installation.html>, I found maybe I can't use Chrono::GPU system and Chrono SMC system in PyChrono. Can you give me any advice? Thank you very much again sincerely! 在2022年11月11日星期五 UTC+8 11:29:20<Ruochun Zhang> 写道：
> Hi, > > What you wanted is possible. There is no problem creating two systems in > one script, the only problem is their interaction. You can do that via > co-simulation. Like a said, *demo_GPU_ballcosim *may give you an idea on > how to do that. The general idea is that your complex mechanical system > involving ChBodies and joints and such, will still be managed by a Chrono > SMC system. Those ChBodies can be instructed to receive external forces and > torques via accumulators; those external forces and torques in this case > should be queried from Chrono::GPU simulations. That is, you load obj > meshes into a Chrono::GPU system, and in each time step, you let it compute > the contact forces between meshes and particles, then feed that information > to ChBodies to update the locations of those bodies, then feed the new > locations of these obj meshes back to Chrono::GPU to complete one time > step, and then repeat. > > If your particle system is large I wouldn't recommend doing runtime > visualization anyway, that'd be totally prohibiting in terms of > computational cost. Chrono::GPU can write particles and meshes to files, > and maybe you should generate movies based on those as a post-processing > step. > > Thank you, > Ruochun > > On Thursday, November 10, 2022 at 6:41:44 AM UTC-6 [email protected] wrote: > >> Hi, thank you for your response! >> First of all, I may have to apologise for my language skills and I really >> appreciate that you are willing to listen to my ideas. I'd like to describe >> my question again. I have finished a complete complex experiment, including >> around 10k granular objects, two objs of my own, one container by using >> *utils::AddBoxGeometry* and several links and motors, such as >> *ChLinkMotorRotationSpeed*、*ChLinkMotorLinearSpeed*、*ChLinkMateFix*. I >> achieved it by using *the MCORE module*, although it can speed up the >> program by using multiple threads, it still took 2 hours four one time >> simulation. >> >> Now I am considering using the reinforcement learning afterwards, so it >> is important to improve the simulation speed. I am wondering if I can use >> *Chrono::GPU* only for my granular objects, and all other content >> remains the same by using *the MCORE module.* More specifically, I plan >> to use both *ChSystemMulticoreSMC* and *ChSystemGpuMesh* in one cpp. The >> reason I want to do this is because *Chrono::GPU* is more like a >> separate module, some of the functions I need for simulation can't be found >> in *Chrono::GPU*, but can be found in *the MCORE module* and are already >> realized through my previous efforts. >> >> I also note that *Chrono::GPU *quote >> ChronoEngine_GPU、ChronoEngine_irrlicht、ChronoEngine_multicore、ChronoEngine_opengl、ChronoEngine_postprocess、ChronoEngine_robot >> >> and *ChronoEngine_multicore(* *the MCORE module* *) *is the one which I >> used now. So I can use MCORE-functions in cpps in *Chrono::GPU*，by >> including the .h insteading of modify the CMakeLists.txt. >> >> I tried and felt if this idea was unattainable. Because I need to create >> two systems in one cpp. Meanwhile, for visualization, >> *opengl::ChVisualSystemOpenGL* is used in *the* *MCORE module *and >> *ChGpuVisualization* is used in *the **Chrono::GPU *and I can't find an >> interface between the two which means they can't be showed in one window. I >> don't know how to solve this problem anymore and I wonder if you have any >> suggestions. >> >> I really appreciate your help! >> >> >> >> 在2022年11月10日星期四 UTC+8 13:29:20<Ruochun Zhang> 写道： >> >>> Hi, >>> >>> I hope someone can provide better help on the linkage issue. What I can >>> say is that you can try building it with cuda11.6 and the newest gcc. If >>> you are using cuda11.8, or an ancient version of cuda or gcc, I cannot be >>> sure. I've been building it with the said configuration with no problem, on >>> Linux or Windows. >>> >>> About Chrono::GPU's usage, yes it supports obj meshes. I am not sure >>> about what you meant by multi-core acceleration. I might, if you elaborate >>> a bit. And Chrono::GPU should interact with Chrono just fine, for that >>> maybe you can have a look at the *ballcosim *demo. >>> >>> If you care about polydisperse spherical particles or complex shaped >>> particles, then DEM-Engine is the way to go. You can start using it now. >>> Indeed, documentations are being added. I can drop you a message when it >>> becomes more accessible. Right now, I attached a snippet from one of my >>> previous emails, to help you understand how to build this tool on Linux. In >>> terms of using it, I'd start with checking out and running its demos. And >>> then, the methods in *API.h* are mostly commented, which for now, may >>> serve as an ad-hoc documentation for you to understand what some of its >>> basic usages are. >>> >>> Thank you, >>> Ruochun >>> On Wednesday, November 9, 2022 at 2:19:40 AM UTC-6 [email protected] >>> wrote: >>> >>>> Hi, thank you very much for your help! >>>> After last mail, I choosed to use the multicore, the simulation took 2 >>>> hours every time now, because I was constantly adding requests and >>>> features and the number of bodies comes to 10k. Meanwhile, I bought a 3080 >>>> and a new computer. I am considering using the reinforcement learning >>>> afterwards, so it is important to improve the simulation speed. >>>> I have studied your response several times，I am wondering if I can only >>>> use Chrono::GPU for my particle-related content, and all other content >>>> remains the same, such as multi-core acceleration, loading my own obj. >>>> More >>>> specifically, I plan to use both ChSystemMulticoreSMC and ChSystemGpuMesh. >>>> When compile the project, there are errors "LNK2019：Unresolvable external >>>> symbols" in every functions defined in GPU and used in the Muticore and I >>>> feel this is a deeper issue involving linkers. So I would like to ask for >>>> guidance or is there another way to use the Chrono::GPU as a DEMsolver >>>> only >>>> for the particles. >>>> And I learned something about projectchrono >>>> <https://github.com/projectchrono>/DEM-Engine >>>> <https://github.com/projectchrono/DEM-Engine>, but I found how to >>>> Install DEM-Engine and the DEM-Engine usage are still waiting to be >>>> added, I would love to try it if I could. >>>> Thank you again! >>>> >>>> 在2022年9月24日星期六 UTC+8 14:45:22<Ruochun Zhang> 写道： >>>> >>>>> Hi, >>>>> >>>>> The GPU module does benefit a lot from more recent hardware. If your >>>>> test case does not feature a huge number of bodies, say some 10k, then >>>>> multicore can be a good choice. It probably requires less learning from >>>>> you >>>>> too. >>>>> >>>>> It should be noted that Chrono::GPU is not "Chrono on GPU". Most >>>>> Chrono core classes and methods cannot be used in Chrono::GPU. For all >>>>> purposes, Chrono::GPU can be seen as a standalone DEM solver for >>>>> monodisperse spherical particles, implemented on GPU. It should be used >>>>> to >>>>> simulate granular materials, and it can interact with Chrono (core) so >>>>> that >>>>> it becomes possible to bring a small number of more complex objects (such >>>>> as your spoon) into the simulation as well. So if you would like to use >>>>> Chrono::GPU, you have to start from its demos, to learn how to use its >>>>> own >>>>> methods to instantiate and manage granular particles. Chrono::GPU's main >>>>> advantage is being fast. If your simulation has to involve millions of >>>>> granular particles, then multicore will not do and GPU is the choice. >>>>> >>>>> More specifically, *CreateCylindricalContainerFromBoxes* is not a >>>>> Chrono::GPU thing at all. *cohesion_ratio* is about the cohesion >>>>> between Chrono::GPU particles, and it has nothing to do with gravity, >>>>> which >>>>> is set by *SetGravitationalAcceleration* in Chrono::GPU. >>>>> >>>>> On a different note, Chrono's DEM/granular support on GPU is moving >>>>> towards a new direction. The support for complex granular particle shapes >>>>> will be added and it will become a duo-GPU solver. It will be based on >>>>> SBEL's >>>>> new DEM Engine <https://github.com/uwsbel/DEM-Engine>. Apart from >>>>> being more general and having higher efficiency, the usage of it is >>>>> similar >>>>> to Chrono::GPU, as a standalone helper to Chrono core which manages the >>>>> granular part of the simulation, or work on its own as a dedicated DEM >>>>> solver. If from the previous conversation you believe Chrono::GPU is for >>>>> you, then likely this package will be of interest. More documentations >>>>> and >>>>> user guides are being added to it. But again, it does benefit from recent >>>>> GPUs though. >>>>> >>>>> Thank you, >>>>> Ruochun >>>>> >>>>> On Sunday, September 18, 2022 at 2:13:24 AM UTC-5 [email protected] >>>>> wrote: >>>>> >>>>>> hello there, >>>>>> I am tring to perform a simulation which I want to put an object like >>>>>> a spoon and scoop the sand(granular objects) to see the force in the >>>>>> process. >>>>>> I find that demo_GPU_mixer.cpp demo can be referenced, but I am not >>>>>> sure whether I need to add a container holding those sand and give the >>>>>> granular objects gravity. If this is so, should I use >>>>>> *CreateCylindricalContainerFromBoxes* to add container and use >>>>>> *cohesion_ratio* in the .json to add the gravity? Also, I am sad >>>>>> that I have a poor GPU so that it really take a long long time to run >>>>>> the >>>>>> gpu module. >>>>>> Then I find that there are also some granular objects demos in the >>>>>> multicore module, I find some demos about a container with granular >>>>>> material. And I can run those demos faster. >>>>>> Now I am confused about what thing to do next is much better. >>>>>> >>>>>> Any help will be appreciated, thank you so much in advance. >>>>>> >>>>> -- 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/8e6dcb70-2812-4b15-aa00-845f77b9c67dn%40googlegroups.com.
