5.0.0/tutorial_demo_crank.html

// =============================================================================

// 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.

//

// =============================================================================

// Authors: Alessandro Tasora

// =============================================================================

//

//  Demo code about

//

//  - constraints and 'motor' objects

//  - using IRRLICHT as a realtime 3D viewer of a slider-crank mechanism

//    simulated with Chrono::Engine.

//  - using the real-time step.

//

// This is just a possible method of integration of Chrono::Engine + Irrlicht;

// many others are possible.

//

// =============================================================================


#include "chrono/core/ChRealtimeStep.h"

#include "chrono/physics/ChSystemNSC.h"

#include "chrono/physics/ChLinkMotorRotationSpeed.h"

#include "chrono_irrlicht/ChIrrApp.h"


// Use the namespaces of Chrono

using namespace chrono;

using namespace chrono::irrlicht;


// Use the main namespaces of Irrlicht

using namespace irr;

using namespace irr::core;

using namespace irr::scene;

using namespace irr::video;

using namespace irr::io;

using namespace irr::gui;


int main(int argc, char* argv[]) {

    GetLog() << "Copyright (c) 2017 projectchrono.org\nChrono version: " << CHRONO_VERSION << "\n\n";


    //

    // HERE YOU CREATE THE MECHANICAL SYSTEM OF CHRONO...

    //


    // 1- Create a Chrono physical system: all bodies and constraints

    //    will be handled by this ChSystemNSC object.


    ChSystemNSC my_system;


    // 2- Create the rigid bodies of the slider-crank mechanical system

    //   (a crank, a rod, a truss), maybe setting position/mass/inertias of

    //   their center of mass (COG) etc.


    // ..the truss

    auto my_body_A = chrono_types::make_shared<ChBody>();

    my_system.AddBody(my_body_A);

    my_body_A->SetBodyFixed(true);  // truss does not move!

    my_body_A->SetName("Ground-Truss");


    // ..the crank

    auto my_body_B = chrono_types::make_shared<ChBody>();

    my_system.AddBody(my_body_B);

    my_body_B->SetPos(ChVector<>(1, 0, 0));  // position of COG of crank

    my_body_B->SetMass(2);

    my_body_B->SetName("Crank");


    // ..the rod

    auto my_body_C = chrono_types::make_shared<ChBody>();

    my_system.AddBody(my_body_C);

    my_body_C->SetPos(ChVector<>(4, 0, 0));  // position of COG of rod

    my_body_C->SetMass(3);

    my_body_C->SetName("Rod");


    // 3- Create constraints: the mechanical joints between the rigid bodies.


    // .. a revolute joint between crank and rod

    auto my_link_BC = chrono_types::make_shared<ChLinkLockRevolute>();

    my_link_BC->SetName("RevJointCrankRod");

    my_link_BC->Initialize(my_body_B, my_body_C, ChCoordsys<>(ChVector<>(2, 0, 0)));

    my_system.AddLink(my_link_BC);


    // .. a slider joint between rod and truss

    auto my_link_CA = chrono_types::make_shared<ChLinkLockPointLine>();

    my_link_CA->SetName("TransJointRodGround");

    my_link_CA->Initialize(my_body_C, my_body_A, ChCoordsys<>(ChVector<>(6, 0, 0)));

    my_system.AddLink(my_link_CA);


    // .. a motor between crank and truss

    auto my_link_AB = chrono_types::make_shared<ChLinkMotorRotationSpeed>();

    my_link_AB->Initialize(my_body_A, my_body_B, ChFrame<>(ChVector<>(0, 0, 0)));

    my_link_AB->SetName("RotationalMotor");

    my_system.AddLink(my_link_AB);

    auto my_speed_function = chrono_types::make_shared<ChFunction_Const>(CH_C_PI);  // speed w=3.145 rad/sec

    my_link_AB->SetSpeedFunction(my_speed_function);


    // 4- Create the Irrlicht visualization

    ChIrrApp application(&my_system, L"Simple slider-crank example", core::dimension2d<u32>(800, 600), false);


    // Easy shortcuts to add camera, lights, logo and sky in Irrlicht scene:

    ChIrrWizard::add_typical_Logo(application.GetDevice());

    ChIrrWizard::add_typical_Sky(application.GetDevice());

    ChIrrWizard::add_typical_Lights(application.GetDevice());

    ChIrrWizard::add_typical_Camera(application.GetDevice(), core::vector3df(0, 0, -6));


    // Bind assets

    application.AssetBindAll();

    application.AssetUpdateAll();


    //

    // THE SOFT-REAL-TIME CYCLE, SHOWING THE SIMULATION

    //


    // This will help choosing an integration step which matches the

    // real-time step of the simulation..

    ChRealtimeStepTimer m_realtime_timer;


    bool removed = false;


    while (application.GetDevice()->run()) {

        // Irrlicht must prepare frame to draw

        application.BeginScene(true, true, SColor(255, 140, 161, 192));


        // Irrlicht now draws simple lines in 3D world representing a

        // skeleton of the mechanism, in this instant:

        //

        // .. draw items belonging to Irrlicht scene, if any

        application.DrawAll();

        // .. draw a grid

        ChIrrTools::drawGrid(application.GetVideoDriver(), 0.5, 0.5);

        // .. draw GUI items belonging to Irrlicht screen, if any

        application.GetIGUIEnvironment()->drawAll();


        // .. draw the rod (from joint BC to joint CA)

        ChIrrTools::drawSegment(application.GetVideoDriver(), my_link_BC->GetMarker1()->GetAbsCoord().pos,

                                my_link_CA->GetMarker1()->GetAbsCoord().pos, video::SColor(255, 0, 255, 0));

        // .. draw the crank (from joint AB to joint BC)

        ChIrrTools::drawSegment(application.GetVideoDriver(), my_link_AB->GetLinkAbsoluteCoords().pos,

                                my_link_BC->GetMarker1()->GetAbsCoord().pos, video::SColor(255, 255, 0, 0));

        // .. draw a small circle at crank origin

        ChIrrTools::drawCircle(application.GetVideoDriver(), 0.1, ChCoordsys<>(ChVector<>(0, 0, 0), QUNIT));


        /* test: delete a link after 10 seconds

        if (my_system.GetChTime() >10 && (!removed))

        {

                my_system.RemoveLink(my_link_AB);

                removed = true;

        }*/


        // HERE CHRONO INTEGRATION IS PERFORMED: THE

        // TIME OF THE SIMULATION ADVANCES FOR A SINGLE

        // STEP:


        my_system.DoStepDynamics(m_realtime_timer.SuggestSimulationStep(0.02));


        // Irrlicht must finish drawing the frame

        application.EndScene();

    }


    return 0;

}