dcagritan
commented
2 years ago Dear Team, so I was doing some experiments and trying to understand the engine. I've tried to create my own demo file that utilizes the FEA terrain formulation. What I did was to modify the demo_VEH_HMMWV_DefSoil and extract/add some parts to it. I've used a direct solver to make sure that I'm having the real solution although it's relatively slow. However, I'm having problems. The vehicle (that we see only the tires of it) just gets through the terrain. So the terrain doesn't apply a resisting force onto the vehicle. I can't figure out what the problem is. Currently, to make things faster I use a coarse mesh(a fine mesh takes a very long time to see the results). Might that be the problem? Am I missing some parts that I have to do? I'm pasting the demo file that I name as demo_VEH_HMMWV_FEA_DefSoil at the bottom of this message. I'm stuck at this stage for days and I would really appreciate your help! Thank you very much and have a nice day. Kind regards, Deniz
// ============================================================================= // PROJECT CHRONO - http://projectchrono.org // // Copyright (c) 2014 projectchrono.org // All rights reserved. // // Use of this source code is governed by a BSD-style license that can be found // in the LICENSE file at the top level of the distribution and at // http://projectchrono.org/license-chrono.txt.
// Chrono::Vehicle + Chrono::Multicore demo program for simulating a HMMWV vehicle // over rigid or granular material. // // Contact uses the SMC (penalty) formulation. // // The global reference frame has Z up. // All units SI. // =============================================================================
include
include
include
include "chrono/utils/ChUtilsInputOutput.h"
include "chrono_vehicle/ChVehicleModelData.h"
include "chrono_vehicle/ChDriver.h"
include "chrono_vehicle/terrain/SCMDeformableTerrain.h"
include "chrono_vehicle/terrain/RigidTerrain.h"
include "chrono_vehicle/terrain/FEADeformableTerrain.h"
include "chrono_vehicle/wheeled_vehicle/utils/ChWheeledVehicleIrrApp.h"
include "chrono/fea/ChVisualizationFEAmesh.h"
include "chrono/solver/ChIterativeSolverLS.h"
include "chrono/solver/ChDirectSolverLS.h"
include "chrono_models/vehicle/hmmwv/HMMWV.h"
include "chrono_thirdparty/filesystem/path.h"
using namespace chrono; using namespace chrono::collision; using namespace chrono::irrlicht; using namespace chrono::vehicle; using namespace chrono::vehicle::hmmwv; using namespace chrono::fea;
using std::cout; using std::endl;
// ============================================================================= // USER SETTINGS // =============================================================================
// ----------------------------------------------------------------------------- // Vehicle parameters // -----------------------------------------------------------------------------
// Type of tire (controls both contact and visualization) enum class TireType { CYLINDRICAL, LUGGED }; TireType tire_type = TireType::LUGGED;
// Tire contact material properties float Y_t = 1.0e6f; float cr_t = 0.1f; float mu_t = 0.8f;
// Initial vehicle position and orientation ChVector<> initLoc(-5, -2, 0.6); ChQuaternion<> initRot(1, 0, 0, 0);
// ----------------------------------------------------------------------------- // Simulation parameters // -----------------------------------------------------------------------------
// Simulation step size double step_size = 2e-2;
// Time interval between two render frames (1/FPS) double render_step_size = 1.0 / 100;
// Point on chassis tracked by the camera ChVector<> trackPoint(0.0, 0.0, 1.75);
// Output directories const std::string out_dir = GetChronoOutputPath() + "HMMWV_DEF_SOIL"; const std::string img_dir = out_dir + "/IMG";
// Visualization output bool img_output = false;
// =============================================================================
class MyDriver : public ChDriver { public: MyDriver(ChVehicle& vehicle, double delay) : ChDriver(vehicle), m_delay(delay) {} ~MyDriver() {}
virtual void Synchronize(double time) override {
m_throttle = 0;
m_steering = 0;
m_braking = 0;
double eff_time = time - m_delay;
// Do not generate any driver inputs for a duration equal to m_delay.
if (eff_time < 0)
return;
if (eff_time > 0.2)
m_throttle = 0.7;
else
m_throttle = 3.5 * eff_time;
if (eff_time < 2)
m_steering = 0;
else
m_steering = 0.6 * std::sin(CH_C_2PI * (eff_time - 2) / 6);
}private: double m_delay; };
// =============================================================================
void CreateLuggedGeometry(std::shared_ptr
auto coll_model = wheel_body->GetCollisionModel();
coll_model->ClearModel();
// Assemble the tire contact from 15 segments, properly offset.
// Each segment is further decomposed in convex hulls.
for (int iseg = 0; iseg < 15; iseg++) {
ChQuaternion<> rot = Q_from_AngAxis(iseg * 24 * CH_C_DEG_TO_RAD, VECT_Y);
for (int ihull = 0; ihull < num_hulls; ihull++) {
std::vector<ChVector<> > convexhull;
lugged_convex.GetConvexHullResult(ihull, convexhull);
coll_model->AddConvexHull(wheel_material, convexhull, VNULL, rot);
}
}
// Add a cylinder to represent the wheel hub.
coll_model->AddCylinder(wheel_material, 0.223, 0.223, 0.126);
coll_model->BuildModel();
// Visualization
auto trimesh = chrono_types::make_shared<geometry::ChTriangleMeshConnected>();
trimesh->LoadWavefrontMesh(vehicle::GetDataFile("hmmwv/lugged_wheel.obj"), false, false);
auto trimesh_shape = chrono_types::make_shared<ChTriangleMeshShape>();
trimesh_shape->SetMesh(trimesh);
trimesh_shape->SetName("lugged_wheel");
wheel_body->AddAsset(trimesh_shape);
auto mcolor = chrono_types::make_shared<ChColorAsset>(0.3f, 0.3f, 0.3f);
wheel_body->AddAsset(mcolor);}
// =============================================================================
int main(int argc, char* argv[]) { GetLog() << "Copyright (c) 2017 projectchrono.org\nChrono version: " << CHRONO_VERSION << "\n\n";
// --------------------
// Create HMMWV vehicle
// --------------------
HMMWV_Full my_hmmwv;
my_hmmwv.SetContactMethod(ChContactMethod::SMC);
my_hmmwv.SetChassisFixed(false);
my_hmmwv.SetInitPosition(ChCoordsys<>(initLoc, initRot));
my_hmmwv.SetPowertrainType(PowertrainModelType::SHAFTS);
my_hmmwv.SetDriveType(DrivelineTypeWV::AWD);
switch (tire_type) {
case TireType::CYLINDRICAL:
my_hmmwv.SetTireType(TireModelType::RIGID_MESH);
break;
case TireType::LUGGED:
my_hmmwv.SetTireType(TireModelType::RIGID);
break;
}
my_hmmwv.Initialize();
my_hmmwv.SetChassisVisualizationType(VisualizationType::NONE);
// -----------------------------------------------------------
// Set tire contact material, contact model, and visualization
// -----------------------------------------------------------
auto wheel_material = chrono_types::make_shared<ChMaterialSurfaceSMC>();
wheel_material->SetFriction(mu_t);
wheel_material->SetYoungModulus(Y_t);
wheel_material->SetRestitution(cr_t);
switch (tire_type) {
case TireType::CYLINDRICAL:
my_hmmwv.SetTireVisualizationType(VisualizationType::MESH);
break;
case TireType::LUGGED:
my_hmmwv.SetTireVisualizationType(VisualizationType::NONE);
for (auto& axle : my_hmmwv.GetVehicle().GetAxles()) {
CreateLuggedGeometry(axle->m_wheels[0]->GetSpindle(), wheel_material);
CreateLuggedGeometry(axle->m_wheels[1]->GetSpindle(), wheel_material);
}
}
// --------------------
// Create driver system
// --------------------
MyDriver driver(my_hmmwv.GetVehicle(), 0.5);
driver.Initialize();
// ------------------
// Create the terrain
// ------------------
ChSystem* system = my_hmmwv.GetSystem();
system->SetNumThreads(std::min(8, ChOMP::GetNumProcs()));
system->SetNumThreads(12);
// FEA Terrain Generation:
FEADeformableTerrain terrain(system);
// Use either a regular grid:
ChVector<> start_point(-7.4, -3.8, -0.5);
ChVector<> terrain_dimension(6.0, 3.5, 0.5);
ChVector<> terrain_discretization(12.0, 7.0, 4.0);
///ChVector<> terrain_discretization(60.0, 35.0, 5.0);
///ChVector<> terrain_discretization(30.0, 18.0, 3.0);
terrain.Initialize(start_point, terrain_dimension, terrain_discretization);
terrain.SetSoilParametersFEA(200.0, ///< Soil density
1.379e7, ///< Soil modulus of elasticity
0.3, ///< Soil Poisson ratio
10000.0, ///< [in] Soil yield stress, for plasticity
5000, ///< [in] Soil hardening slope, for plasticity
0.00001, ///< Soil internal friction angle
0.00001 ///< Soil dilatancy angle
);
auto mvisualizemeshref = chrono_types::make_shared<ChVisualizationFEAmesh>(*(terrain.GetMesh()));
mvisualizemeshref->SetFEMdataType(ChVisualizationFEAmesh::E_PLOT_SURFACE);
mvisualizemeshref->SetWireframe(true);
mvisualizemeshref->SetDrawInUndeformedReference(true);
terrain.GetMesh()->AddAsset(mvisualizemeshref);
auto mvisualizemeshcoll = chrono_types::make_shared<ChVisualizationFEAmesh>(*(terrain.GetMesh()));
mvisualizemeshcoll->SetFEMdataType(ChVisualizationFEAmesh::E_PLOT_CONTACTSURFACES);
mvisualizemeshcoll->SetWireframe(true);
mvisualizemeshcoll->SetDefaultMeshColor(ChColor(1, 0.5, 0));
terrain.GetMesh()->AddAsset(mvisualizemeshcoll);
// ---------------------------------------
// Create the vehicle Irrlicht application
// ---------------------------------------
ChWheeledVehicleIrrApp app(&my_hmmwv.GetVehicle(), L"HMMWV Deformable Soil Demo");
app.SetSkyBox();
app.AddTypicalLights(irr::core::vector3df(30.f, -30.f, 100.f), irr::core::vector3df(30.f, 50.f, 100.f), 250, 130);
app.SetChaseCamera(trackPoint, 6.0, 0.5);
app.SetTimestep(step_size);
app.AssetBindAll();
app.AssetUpdateAll();
// -----------------
// Initialize output
// -----------------
if (!filesystem::create_directory(filesystem::path(out_dir))) {
std::cout << "Error creating directory " << out_dir << std::endl;
return 1;
}
if (img_output) {
if (!filesystem::create_directory(filesystem::path(img_dir))) {
std::cout << "Error creating directory " << img_dir << std::endl;
return 1;
}
}
// ---------------
// Simulation loop
// ---------------
std::cout << "Total vehicle mass: " << my_hmmwv.GetTotalMass() << std::endl;
// Solver settings.
auto solver = chrono_types::make_shared<ChSolverSparseLU>();
system->SetSolver(solver);
solver->SetVerbose(true);
// Number of simulation steps between two 3D view render frames
int render_steps = (int)std::ceil(render_step_size / step_size);
// Initialize simulation frame counter
int step_number = 0;
int render_frame = 0;
ChTimer<> timer;
while (app.GetDevice()->run()) {
double time = system->GetChTime();
std::cout << "\ntime = " << time << std::endl;
if (step_number == 800) {
std::cout << "\nstart timer at t = " << time << std::endl;
timer.start();
}
if (step_number == 1400) {
timer.stop();
std::cout << "stop timer at t = " << time << std::endl;
std::cout << "elapsed: " << timer() << std::endl;
std::cout << "\nSCM stats for last step:" << std::endl;
///terrain.PrintStepStatistics(std::cout);
}
// Render scene
app.BeginScene(true, true, irr::video::SColor(255, 140, 161, 192));
app.DrawAll();
ChIrrTools::drawColorbar(0, 0.1, "Sinkage", app.GetDevice(), 30);
app.EndScene();
if (img_output && step_number % render_steps == 0) {
char filename[100];
sprintf(filename, "%s/img_%03d.jpg", img_dir.c_str(), render_frame + 1);
app.WriteImageToFile(filename);
render_frame++;
}
// Driver inputs
ChDriver::Inputs driver_inputs = driver.GetInputs();
// Update modules
driver.Synchronize(time);
terrain.Synchronize(time);
my_hmmwv.Synchronize(time, driver_inputs, terrain);
app.Synchronize("", driver_inputs);
// Advance simulation for one timestep for all modules
driver.Advance(step_size);
terrain.Advance(step_size);
my_hmmwv.Advance(step_size);
app.Advance(step_size);
// Increment frame number
step_number++;
}
return 0;}
Dear Chrono Team, as far as I see, there is no demo for Deformable FEA Terrain among the demos that are compiled with the project. Is there any possibility to have such a demo file or sample project? I'm trying to model soil with FEA and such a file or a project would make things way easier for me. Thank you very much for all the great work and have a great day! Best regards,