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32 
33 #include <gtest/gtest.h>
34 
35 #include "dart/dynamics/SimpleFrame.hpp"
36 #include "dart/math/Helpers.hpp"
37 #include "dart/math/Random.hpp"
38 
39 #include "TestHelpers.hpp"
40 
41 using namespace dart;
42 using namespace dynamics;
43 
44 //==============================================================================
createFloor()45 dynamics::SkeletonPtr createFloor()
46 {
47   auto floor = dynamics::Skeleton::create("floor");
48 
49   // Give the floor a body
50   auto body
51       = floor->createJointAndBodyNodePair<dynamics::WeldJoint>(nullptr).second;
52 
53   // Give the body a shape
54   double floorWidth = 10.0;
55   double floorHeight = 0.01;
56   auto box = std::make_shared<dynamics::BoxShape>(
57       Eigen::Vector3d(floorWidth, floorWidth, floorHeight));
58   auto* shapeNode = body->createShapeNodeWith<
59       dynamics::VisualAspect,
60       dynamics::CollisionAspect,
61       dynamics::DynamicsAspect>(box);
62   shapeNode->getVisualAspect()->setColor(dart::Color::LightGray());
63 
64   // Put the body into position
65   Eigen::Isometry3d tf = Eigen::Isometry3d::Identity();
66   tf.translation() = Eigen::Vector3d(0.0, 0.0, -0.5 - floorHeight / 2.0);
67   body->getParentJoint()->setTransformFromParentBodyNode(tf);
68 
69   return floor;
70 }
71 
72 //==============================================================================
TEST(Friction,FrictionPerShapeNode)73 TEST(Friction, FrictionPerShapeNode)
74 {
75   auto skeleton1
76       = createBox(Eigen::Vector3d(0.3, 0.3, 0.3), Eigen::Vector3d(-0.5, 0, 0));
77   skeleton1->setName("Skeleton1");
78   auto skeleton2
79       = createBox(Eigen::Vector3d(0.3, 0.3, 0.3), Eigen::Vector3d(+0.5, 0, 0));
80   skeleton2->setName("Skeleton2");
81   auto skeleton3 = createBox(
82       Eigen::Vector3d(0.3, 0.3, 0.3),
83       Eigen::Vector3d(+1.5, 0, 0),
84       Eigen::Vector3d(0, 0, 0.7853981633974483));
85   skeleton3->setName("Skeleton3");
86   auto skeleton4 = createBox(
87       Eigen::Vector3d(0.3, 0.3, 0.3),
88       Eigen::Vector3d(-1.5, 0, 0),
89       Eigen::Vector3d(0, 0, 0.7853981633974483));
90   skeleton4->setName("Skeleton4");
91 
92   auto body1 = skeleton1->getRootBodyNode();
93   // default friction values
94   EXPECT_DOUBLE_EQ(
95       1.0, body1->getShapeNode(0)->getDynamicsAspect()->getFrictionCoeff());
96   EXPECT_DOUBLE_EQ(
97       1.0,
98       body1->getShapeNode(0)->getDynamicsAspect()->getPrimaryFrictionCoeff());
99   EXPECT_DOUBLE_EQ(
100       1.0,
101       body1->getShapeNode(0)->getDynamicsAspect()->getSecondaryFrictionCoeff());
102 
103   auto body2 = skeleton2->getRootBodyNode();
104   // default friction values
105   EXPECT_DOUBLE_EQ(
106       1.0, body2->getShapeNode(0)->getDynamicsAspect()->getFrictionCoeff());
107   EXPECT_DOUBLE_EQ(
108       1.0,
109       body2->getShapeNode(0)->getDynamicsAspect()->getPrimaryFrictionCoeff());
110   EXPECT_DOUBLE_EQ(
111       1.0,
112       body2->getShapeNode(0)->getDynamicsAspect()->getSecondaryFrictionCoeff());
113   // test setting primary friction
114   body2->getShapeNode(0)->getDynamicsAspect()->setPrimaryFrictionCoeff(0.5);
115   EXPECT_DOUBLE_EQ(
116       0.75, body2->getShapeNode(0)->getDynamicsAspect()->getFrictionCoeff());
117   EXPECT_DOUBLE_EQ(
118       0.5,
119       body2->getShapeNode(0)->getDynamicsAspect()->getPrimaryFrictionCoeff());
120   EXPECT_DOUBLE_EQ(
121       1.0,
122       body2->getShapeNode(0)->getDynamicsAspect()->getSecondaryFrictionCoeff());
123   // test setting secondary friction
124   body2->getShapeNode(0)->getDynamicsAspect()->setSecondaryFrictionCoeff(0.25);
125   EXPECT_DOUBLE_EQ(
126       0.375, body2->getShapeNode(0)->getDynamicsAspect()->getFrictionCoeff());
127   EXPECT_DOUBLE_EQ(
128       0.5,
129       body2->getShapeNode(0)->getDynamicsAspect()->getPrimaryFrictionCoeff());
130   EXPECT_DOUBLE_EQ(
131       0.25,
132       body2->getShapeNode(0)->getDynamicsAspect()->getSecondaryFrictionCoeff());
133   // set all friction coeffs to 0.0
134   body2->getShapeNode(0)->getDynamicsAspect()->setFrictionCoeff(0.0);
135   EXPECT_DOUBLE_EQ(
136       0.0, body2->getShapeNode(0)->getDynamicsAspect()->getFrictionCoeff());
137   EXPECT_DOUBLE_EQ(
138       0.0,
139       body2->getShapeNode(0)->getDynamicsAspect()->getPrimaryFrictionCoeff());
140   EXPECT_DOUBLE_EQ(
141       0.0,
142       body2->getShapeNode(0)->getDynamicsAspect()->getSecondaryFrictionCoeff());
143 
144   auto body3 = skeleton3->getRootBodyNode();
145   // default friction values
146   EXPECT_DOUBLE_EQ(
147       1.0, body3->getShapeNode(0)->getDynamicsAspect()->getFrictionCoeff());
148   EXPECT_DOUBLE_EQ(
149       1.0,
150       body3->getShapeNode(0)->getDynamicsAspect()->getPrimaryFrictionCoeff());
151   EXPECT_DOUBLE_EQ(
152       1.0,
153       body3->getShapeNode(0)->getDynamicsAspect()->getSecondaryFrictionCoeff());
154   EXPECT_DOUBLE_EQ(
155       0.0,
156       body3->getShapeNode(0)
157           ->getDynamicsAspect()
158           ->getFirstFrictionDirection()
159           .squaredNorm());
160   EXPECT_EQ(
161       nullptr,
162       body3->getShapeNode(0)
163           ->getDynamicsAspect()
164           ->getFirstFrictionDirectionFrame());
165   // this body is rotated by 45 degrees, so set friction direction in body frame
166   // along Y axis so that gravity pushes it in x and y
167   body3->getShapeNode(0)->getDynamicsAspect()->setPrimaryFrictionCoeff(0.0);
168   body3->getShapeNode(0)->getDynamicsAspect()->setFirstFrictionDirection(
169       Eigen::Vector3d(0, 1, 0));
170   // check friction values
171   EXPECT_DOUBLE_EQ(
172       0.5, body3->getShapeNode(0)->getDynamicsAspect()->getFrictionCoeff());
173   EXPECT_DOUBLE_EQ(
174       0.0,
175       body3->getShapeNode(0)->getDynamicsAspect()->getPrimaryFrictionCoeff());
176   EXPECT_DOUBLE_EQ(
177       1.0,
178       body3->getShapeNode(0)->getDynamicsAspect()->getSecondaryFrictionCoeff());
179   EXPECT_DOUBLE_EQ(
180       1.0,
181       body3->getShapeNode(0)
182           ->getDynamicsAspect()
183           ->getFirstFrictionDirection()
184           .squaredNorm());
185   EXPECT_EQ(
186       nullptr,
187       body3->getShapeNode(0)
188           ->getDynamicsAspect()
189           ->getFirstFrictionDirectionFrame());
190 
191   auto body4 = skeleton4->getRootBodyNode();
192   // default friction values
193   EXPECT_DOUBLE_EQ(
194       1.0, body4->getShapeNode(0)->getDynamicsAspect()->getFrictionCoeff());
195   EXPECT_DOUBLE_EQ(
196       1.0,
197       body4->getShapeNode(0)->getDynamicsAspect()->getPrimaryFrictionCoeff());
198   EXPECT_DOUBLE_EQ(
199       1.0,
200       body4->getShapeNode(0)->getDynamicsAspect()->getSecondaryFrictionCoeff());
201   EXPECT_DOUBLE_EQ(
202       0.0,
203       body4->getShapeNode(0)
204           ->getDynamicsAspect()
205           ->getFirstFrictionDirection()
206           .squaredNorm());
207   EXPECT_EQ(
208       nullptr,
209       body4->getShapeNode(0)
210           ->getDynamicsAspect()
211           ->getFirstFrictionDirectionFrame());
212   // this body is rotated by 45 degrees, but set friction direction according to
213   // world frame so that the body orientation doesn't matter. thus a diagonal
214   // axis is needed to push it in x and y
215   body4->getShapeNode(0)->getDynamicsAspect()->setPrimaryFrictionCoeff(0.0);
216   body4->getShapeNode(0)->getDynamicsAspect()->setFirstFrictionDirectionFrame(
217       Frame::World());
218   body4->getShapeNode(0)->getDynamicsAspect()->setFirstFrictionDirection(
219       Eigen::Vector3d(0.5 * std::sqrt(2), 0.5 * std::sqrt(2), 0));
220   // check friction values
221   EXPECT_DOUBLE_EQ(
222       0.5, body4->getShapeNode(0)->getDynamicsAspect()->getFrictionCoeff());
223   EXPECT_DOUBLE_EQ(
224       0.0,
225       body4->getShapeNode(0)->getDynamicsAspect()->getPrimaryFrictionCoeff());
226   EXPECT_DOUBLE_EQ(
227       1.0,
228       body4->getShapeNode(0)->getDynamicsAspect()->getSecondaryFrictionCoeff());
229   EXPECT_DOUBLE_EQ(
230       1.0,
231       body4->getShapeNode(0)
232           ->getDynamicsAspect()
233           ->getFirstFrictionDirection()
234           .squaredNorm());
235   EXPECT_EQ(
236       Frame::World(),
237       body4->getShapeNode(0)
238           ->getDynamicsAspect()
239           ->getFirstFrictionDirectionFrame());
240 
241   // Create a world and add the rigid body
242   auto world = simulation::World::create();
243   EXPECT_TRUE(equals(world->getGravity(), ::Eigen::Vector3d(0, 0, -9.81)));
244   world->setGravity(Eigen::Vector3d(0.0, -5.0, -9.81));
245   EXPECT_TRUE(equals(world->getGravity(), ::Eigen::Vector3d(0.0, -5.0, -9.81)));
246 
247   world->addSkeleton(createFloor());
248   world->addSkeleton(skeleton1);
249   world->addSkeleton(skeleton2);
250   world->addSkeleton(skeleton3);
251   world->addSkeleton(skeleton4);
252 
253   const auto numSteps = 500;
254   for (auto i = 0u; i < numSteps; ++i)
255   {
256     world->step();
257 
258     // Wait until the first box settle-in on the ground
259     if (i > 300)
260     {
261       const auto x1 = body1->getTransform().translation()[0];
262       const auto y1 = body1->getTransform().translation()[1];
263       EXPECT_NEAR(x1, -0.5, 0.00001);
264       EXPECT_NEAR(y1, -0.17889, 0.001);
265 
266       // The second box still moves even after landing on the ground because its
267       // friction is zero.
268       const auto x2 = body2->getTransform().translation()[0];
269       const auto y2 = body2->getTransform().translation()[1];
270       EXPECT_NEAR(x2, 0.5, 0.00001);
271       EXPECT_LE(y2, -0.17889);
272 
273       // The third box still moves even after landing on the ground because its
274       // friction is zero along the first friction direction.
275       const auto x3 = body3->getTransform().translation()[0];
276       const auto y3 = body3->getTransform().translation()[1];
277       EXPECT_GE(x3, 1.5249);
278       EXPECT_LE(y3, -0.20382);
279 
280       // The fourth box still moves even after landing on the ground because its
281       // friction is zero along the first friction direction.
282       const auto x4 = body4->getTransform().translation()[0];
283       const auto y4 = body4->getTransform().translation()[1];
284       EXPECT_LE(x4, -1.5249);
285       EXPECT_LE(y4, -0.20382);
286     }
287   }
288 }
289