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Update examples and documentation (#176)
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‎config.h.in‎

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/*Use Webots*/
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#cmakedefine BITRL_WEBOTS
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/*Use Chron*/
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/*Use Chrono*/
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#cmakedefine BITRL_CHRONO
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/*Use OpenCV*/

‎examples/CMakeLists.txt‎

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@@ -29,6 +29,7 @@ ADD_SUBDIRECTORY(example_2)
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ADD_SUBDIRECTORY(example_3)
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ADD_SUBDIRECTORY(example_4)
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ADD_SUBDIRECTORY(example_5)
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ADD_SUBDIRECTORY(example_6)
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ADD_SUBDIRECTORY(example_7)
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ADD_SUBDIRECTORY(example_8)
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ADD_SUBDIRECTORY(example_9)

‎examples/example_11/example_11.md‎

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@@ -3,14 +3,14 @@
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The <a href="https://github.com/projectchrono/chrono">Chrono</a> library is the main library that _bitrl_ is using in order
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to simulate robots and create environments for reinforcement learning agents. As such, knowing your way around
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Chrono is essential. However, Chrono is a relatively large library with many components and therefore not necessarily easy
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to grasp. In a series of examples, we will see main components of the library that _bitrl_ utilizes.
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to grasp. In a series of examples, we will see the main components of the library that _bitrl_ utilizes.
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Note that you should have compiled Chrono with <a href="https://irrlicht.sourceforge.io/">Irrlicht</a> support in order to be able to run this example.
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The main interface for creating rigid bodies in Chrono is the <a href="https://api.projectchrono.org/9.0.0/classchrono_1_1_ch_body.html">ChBody</a>
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class. You can also find this <a href="https://api.projectchrono.org/9.0.0/rigid_bodies.html"> Rigid Bodies</a> helpful.
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_ChBody_ is an abstract class, and therefore we cannot instantiate it directly. Chrono provides various classes however we can
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_ChBody_ is an abstract class, and therefore we cannot instantiate it directly. Chrono provides various classes however, we can
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immediately use. The one we will use in this example is the _ChBodyEasyBox_ class. This is defined in the _chrono/physics/ChBodyEasy.h_ header.
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Let's first create a box and try to visualize it. Below is the function that constructs a box.
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Let's first create a box and try to visualize it. The function below does exactly that.
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@code{.cpp}
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std::shared_ptr<chrono::ChBody> create_box(real_t xlength, real_t ylength, real_t zlength,
@@ -30,12 +30,14 @@ real_t density, bool create_visualization)
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@endcode
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The following is a helper for setting up the visualization
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The following is a helper for setting up the visualization. We need to build Chrono with Irrlicht support in order to be able to
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use it as a visualization engine. You can find more information about the
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visualisation system in Chrono at <a href="https://api.projectchrono.org/9.0.0/visualization_system.html">Visualization System</a>.
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@code{.cpp}
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void prepare_visualization(chrono::irrlicht::ChVisualSystemIrrlicht& visual)
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{
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visual.SetWindowSize(WINDOW_WIDTH, WINDOW_WIDTH); //WINDOW_HEIGHT);
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visual.SetWindowSize(WINDOW_WIDTH, WINDOW_WIDTH);
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visual.SetWindowTitle(WINDOW_TITLE);
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visual.Initialize();
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@@ -47,8 +49,9 @@ visual.Initialize();
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}
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@endcode
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Below is the main function:
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Below is the main driver for this example.
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It creates a box and attaches it to a _ChSystem_ (see <a href="https://api.projectchrono.org/9.0.0/simulation_system.html">Simulation system</a> for more information).
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It also sets up a minimal visualization obejct _ChVisualSystemIrrlicht_ for the simulation and finally runs the simulation loop.
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@code{.cpp}
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int main()
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{

‎examples/example_13/example_13.cpp‎

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#endif
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#include "bitrl/bitrl_consts.h"
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#include "bitrl/rigid_bodies/chrono_robots/diff_drive_robot.h"
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#include "chrono/core/ChRealtimeStep.h"
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#include "chrono/physics/ChSystemNSC.h"
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#include <chrono/physics/ChSystemSMC.h>
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#include <chrono/physics/ChBodyEasy.h>
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#include "chrono/assets/ChVisualSystem.h"
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#include <chrono_irrlicht/ChVisualSystemIrrlicht.h>
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#include "bitrl/rigid_bodies/chrono_robots/diff_drive_robot.h"
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// #include "chrono/assets/ChColorAsset.h"
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// #include "chrono/assets/ChLineShape.h"
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#include <filesystem>
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#include <string>
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namespace example_13
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{
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using namespace bitrl;
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using namespace chrono::irrlicht;
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// constants we will be using further below
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const uint_t WINDOW_HEIGHT = 800;
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const uint_t WINDOW_WIDTH = 1024;
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const real_t DT = 0.01;
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const real_t SIM_TIME = 5.0;
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const std::string WINDOW_TITLE( "Example 13");
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void prepare_visualization(chrono::irrlicht::ChVisualSystemIrrlicht& visual)
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{
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visual.SetWindowSize(WINDOW_WIDTH, WINDOW_WIDTH); //WINDOW_HEIGHT);
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visual.SetWindowTitle(WINDOW_TITLE);
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visual.Initialize();
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visual.AddLogo();
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visual.AddSkyBox();
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visual.AddCamera({0, -2, 1}, {0, 0, 0});
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visual.AddTypicalLights();
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visual.BindAll();
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}
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48-
29+
#include "chrono/physics/ChSystemNSC.h"
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#include "chrono/physics/ChBodyEasy.h"
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#include "chrono/physics/ChLinkMotorRotationSpeed.h"
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#include "chrono/functions/ChFunctionConst.h"
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#include "chrono_irrlicht/ChVisualSystemIrrlicht.h"
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51-
} // namespace example_13
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using namespace chrono;
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using namespace chrono::irrlicht;
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53-
int main()
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namespace
5440
{
55-
using namespace example_13;
56-
chrono::ChSystemNSC sys;
57-
sys.SetGravitationalAcceleration(chrono::ChVector3d(0, 0, -9.81));
58-
59-
sys.SetCollisionSystemType(chrono::ChCollisionSystem::Type::BULLET);
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chrono::ChCollisionModel::SetDefaultSuggestedEnvelope(0.0025);
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chrono::ChCollisionModel::SetDefaultSuggestedMargin(0.0025);
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auto floor_mat = chrono_types::make_shared<chrono::ChContactMaterialNSC>();
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auto mfloor = chrono_types::make_shared<chrono::ChBodyEasyBox>(20, 20, 1, 1000, true, true, floor_mat);
65-
mfloor->SetPos(chrono::ChVector3d(0, 0, -1));
66-
mfloor->SetFixed(true);
67-
mfloor->GetVisualShape(0)->SetTexture(chrono::GetChronoDataFile("textures/concrete.jpg"));
68-
sys.Add(mfloor);
41+
void draw_world_axes(chrono::irrlicht::ChVisualSystemIrrlicht& vis,
42+
double scale = 1.0) {
43+
auto* driver = vis.GetVideoDriver();
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45+
// X axis (red)
46+
driver->draw3DLine(
47+
{0, 0, 0},
48+
{static_cast<float>(scale), 0, 0},
49+
irr::video::SColor(255, 255, 0, 0));
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51+
// Y axis (green)
52+
driver->draw3DLine(
53+
{0, 0, 0},
54+
{0, static_cast<float>(scale), 0},
55+
irr::video::SColor(255, 0, 255, 0));
56+
57+
// Z axis (blue)
58+
driver->draw3DLine(
59+
{0, 0, 0},
60+
{0, 0, static_cast<float>(scale)},
61+
irr::video::SColor(255, 0, 0, 255));
62+
}
63+
}
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70-
bitrl::rb::bitrl_chrono::CHRONO_DiffDriveRobot robot(sys,
71-
chrono::ChVector3d(0, 0, -0.45), chrono::QUNIT);
65+
int main() {
66+
67+
// -----------------------------
68+
// Create Chrono physical system
69+
// -----------------------------
70+
ChSystemNSC system;
71+
//ChSystemSMC system;
72+
system.SetGravitationalAcceleration(chrono::ChVector3d(0,0,-9.81));
73+
system.SetCollisionSystemType(chrono::ChCollisionSystem::Type::BULLET);
74+
75+
// -----------------------------
76+
// Create ground
77+
// -----------------------------
78+
auto material = chrono_types::make_shared<ChContactMaterialNSC>();
79+
80+
material->SetFriction(0.8f);
81+
material->SetRestitution(0.1f);
82+
auto floor = chrono_types::make_shared<chrono::ChBodyEasyBox>(
83+
5, 5, 0.1, // size
84+
1000, // density
85+
true, true, material); // visual + collision
86+
87+
floor->SetPos(chrono::ChVector3d(0,0,-0.05));
88+
floor->SetFixed(true);
89+
floor->EnableCollision(true);
90+
91+
system.Add(floor);
92+
93+
// -----------------------------
94+
// Robot chassis
95+
// -----------------------------
96+
double wheel_radius = 0.1;
97+
double chassis_height = 0.1;
98+
auto chassis = chrono_types::make_shared<ChBodyEasyBox>(
99+
0.5, 0.3, chassis_height,
100+
1000,
101+
true, true, material);
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103+
// 0,0,wheel_radius + chassis_height/2.0
104+
//chrono::ChVector3d pos(0,0,0.2);
105+
chrono::ChVector3d pos(0.0, 0.0, wheel_radius + chassis_height/2.0 + 0.01);
106+
chassis->SetPos(pos);
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108+
chrono::ChVector3d vel(0.5, 0.0, 0.0);
109+
chassis->SetPosDt(vel);
110+
system.Add(chassis);
111+
112+
// -----------------------------
113+
// Wheels
114+
// -----------------------------
115+
116+
double wheel_width = 0.05;
117+
//auto material = chrono_types::make_shared<chrono::ChContactMaterialNSC>();
118+
auto left_wheel = chrono_types::make_shared<chrono::ChBodyEasyCylinder>(
119+
chrono::ChAxis::Y,
120+
wheel_radius,
121+
wheel_width,
122+
1000,
123+
true, true, material);
124+
125+
auto right_wheel = chrono_types::make_shared<chrono::ChBodyEasyCylinder>(
126+
chrono::ChAxis::Y,
127+
wheel_radius,
128+
wheel_width,
129+
1000,
130+
true, true, material);
131+
132+
left_wheel->SetPos(chrono::ChVector3d(0, 0.2, 0.1));
133+
right_wheel->SetPos(chrono::ChVector3d(0,-0.2, 0.1));
134+
135+
system.Add(left_wheel);
136+
system.Add(right_wheel);
137+
138+
// -----------------------------
139+
// Motors (differential drive)
140+
// -----------------------------
141+
auto motor_left = chrono_types::make_shared<chrono::ChLinkMotorRotationSpeed>();
142+
auto motor_right = chrono_types::make_shared<chrono::ChLinkMotorRotationSpeed>();
143+
144+
chrono::ChQuaternion<> rot = chrono::QuatFromAngleX(chrono::CH_PI_2);
145+
motor_left->Initialize(
146+
left_wheel,
147+
chassis,
148+
chrono::ChFrame<>(chrono::ChVector3d(0,0.2,0.1), rot)
149+
);
150+
151+
motor_right->Initialize(
152+
right_wheel,
153+
chassis,
154+
chrono::ChFrame<>(chrono::ChVector3d(0,-0.2,0.1), rot)
155+
);
156+
157+
system.Add(motor_left);
158+
system.Add(motor_right);
159+
160+
// -----------------------------
161+
// Wheel speeds
162+
// -----------------------------
163+
auto speed_left = chrono_types::make_shared<chrono::ChFunctionConst>(-4.5);
164+
auto speed_right = chrono_types::make_shared<chrono::ChFunctionConst>(-4.5);
165+
166+
motor_left->SetSpeedFunction(speed_left);
167+
motor_right->SetSpeedFunction(speed_right);
168+
169+
double caster_radius = 0.05;
170+
auto caster = chrono_types::make_shared<ChBodyEasySphere>(
171+
caster_radius, // radius
172+
1000, // density
173+
true, // visualization
174+
true, // collision
175+
material);
176+
177+
caster->SetPos(chrono::ChVector3d(0.2, 0, 0.05));
178+
caster->EnableCollision(true);
179+
180+
system.Add(caster);
181+
182+
auto caster_joint = chrono_types::make_shared<ChLinkLockRevolute>();
183+
184+
caster_joint->Initialize(
185+
caster,
186+
chassis,
187+
ChFrame<>(chrono::ChVector3d(-0.25, 0, caster_radius), QUNIT));
188+
189+
system.Add(caster_joint);
190+
191+
floor->EnableCollision(true);
192+
chassis->EnableCollision(true);
193+
left_wheel->EnableCollision(true);
194+
right_wheel->EnableCollision(true);
195+
196+
// -----------------------------
197+
// Irrlicht visualization
198+
// -----------------------------
199+
chrono::irrlicht::ChVisualSystemIrrlicht vis;
200+
201+
vis.AttachSystem(&system);
202+
203+
vis.SetWindowSize(1280,720);
204+
vis.SetWindowTitle("Chrono Differential Drive Robot");
205+
206+
vis.Initialize();
207+
vis.AddSkyBox();
208+
vis.AddLogo();
209+
vis.AddSkyBox();
210+
vis.AddCamera({0, -2, 1}, {0, 0, 0});
211+
vis.AddTypicalLights();
212+
vis.BindAll();
213+
// 1 meter length
214+
// -----------------------------
215+
// Simulation loop
216+
// -----------------------------
217+
double step_size = 0.002;
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73-
robot.init();
74-
robot.set_motor_speed(bitrl::consts::maths::PI, 0);
75-
robot.set_motor_speed(bitrl::consts::maths::PI, 1);
219+
while (vis.Run()) {
76220

77-
chrono::irrlicht::ChVisualSystemIrrlicht visual;
78-
prepare_visualization(visual);
79-
visual.AttachSystem(&sys);
221+
vis.BeginScene();
222+
vis.Render();
223+
draw_world_axes(vis, 2.0);
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81-
// Simulation loop
225+
auto position = chassis -> GetPos();
226+
std::cout << position <<std::endl;
82227

83-
// Timer for enforcing soft real-time
84-
chrono::ChRealtimeStepTimer realtime_timer;
85-
86-
// bool removed = false;
87-
while (visual.Run()) {
88-
// Irrlicht must prepare frame to draw
89-
visual.BeginScene();
90-
91-
// Irrlicht now draws simple lines in 3D world representing a
92-
// skeleton of the mechanism, in this instant:
93-
//
94-
// .. draw items belonging to Irrlicht scene, if any
95-
visual.Render();
96-
// .. draw a grid
97-
tools::drawGrid(&visual, 0.5, 0.5);
98-
// .. draw GUI items belonging to Irrlicht screen, if any
99-
visual.GetGUIEnvironment()->drawAll();
100-
101-
// ADVANCE SYSTEM STATE BY ONE STEP
102-
sys.DoStepDynamics(DT);
103-
104-
// Enforce soft real-time
105-
realtime_timer.Spin(DT);
106-
107-
// Irrlicht must finish drawing the frame
108-
visual.EndScene();
228+
system.DoStepDynamics(step_size);
229+
vis.EndScene();
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}
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return 0;

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