// Copyright 2022 DeepMind Technologies Limited // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. // Tests for plugin-related functionalities. #include #include #include #include #include #include #include "test/fixture.h" namespace mujoco { namespace { using ElasticityTest = PluginTest; // -------------------------------- flex ------------------------------------ TEST_F(ElasticityTest, FlexCompatibility) { static constexpr char flex_xml[] = R"( )"; char error[1024] = {0}; mjModel* m = LoadModelFromString(flex_xml, error, sizeof(error)); ASSERT_THAT(m, testing::NotNull()) << error; mjData* d = mj_makeData(m); mj_deleteData(d); mj_deleteModel(m); } // -------------------------------- shell ----------------------------------- TEST_F(ElasticityTest, ElasticEnergyShell) { static constexpr char cantilever_xml[] = R"( )"; char error[1024] = {0}; mjModel* m = LoadModelFromString(cantilever_xml, error, sizeof(error)); ASSERT_THAT(m, testing::NotNull()) << error; mjData* d = mj_makeData(m); mj_kinematics(m, d); mj_flex(m, d); // check that a plane is in the kernel of the energy for (mjtNum scale = 1; scale < 4; scale++) { for (int e = 0; e < m->flex_edgenum[0]; e++) { int* edge = m->flex_edge + 2*(m->flex_edgeadr[0] + e); int* flap = m->flex_edgeflap + 2*(m->flex_edgeadr[0] + e); int v[4] = {edge[0], edge[1], flap[0], flap[1]}; if (v[3]== -1) { continue; } mjtNum energy = 0; mjtNum volume = 1./2.; for (int i = 0; i < 4; i++) { for (int j = 0; j < 4; j++) { for (int x = 0; x < 3; x++) { mjtNum elongation1 = scale * d->flexvert_xpos[3*v[i]+x]; mjtNum elongation2 = scale * d->flexvert_xpos[3*v[j]+x]; energy += m->flex_bending[16*e+4*i+j] * elongation1 * elongation2; } } } EXPECT_NEAR( 4*energy/volume, 0, std::numeric_limits::epsilon()); } } mj_deleteData(d); mj_deleteModel(m); } // -------------------------------- membrane ----------------------------------- TEST_F(PluginTest, ElasticEnergyMembrane) { static constexpr char cantilever_xml[] = R"( )"; char error[1024] = {0}; mjModel* m = LoadModelFromString(cantilever_xml, error, sizeof(error)); ASSERT_THAT(m, testing::NotNull()) << error; mjData* d = mj_makeData(m); mj_kinematics(m, d); mj_flex(m, d); mjtNum* metric = m->flex_stiffness + 21 * m->flex_elemadr[0]; // check that if the entire geometry is rescaled by a factor "scale", then // trace(strain^2) = 2*scale^2 for (mjtNum scale = 1; scale < 4; scale++) { for (int t = 0; t < m->flex_elemnum[0]; t++) { mjtNum energy = 0; mjtNum volume = 1./2.; int idx = 0; for (int e1 = 0; e1 < 3; e1++) { for (int e2 = e1; e2 < 3; e2++) { int idx1 = m->flex_elemedge[3*t+e1 + m->flex_elemedgeadr[0]]; int idx2 = m->flex_elemedge[3*t+e2 + m->flex_elemedgeadr[0]]; mjtNum elong1 = scale * m->flexedge_length0[idx1] * m->flexedge_length0[idx1]; mjtNum elong2 = scale * m->flexedge_length0[idx2] * m->flexedge_length0[idx2]; energy += metric[21*t+idx++] * elong1 * elong2 * (e1 == e2 ? 1. : 2.); } } EXPECT_NEAR( 4*energy/volume, 2*scale*scale, std::numeric_limits::epsilon()); } } mj_deleteData(d); mj_deleteModel(m); } // -------------------------------- solid ----------------------------------- TEST_F(ElasticityTest, ElasticEnergySolid) { static constexpr char cantilever_xml[] = R"( )"; char error[1024] = {0}; mjModel* m = LoadModelFromString(cantilever_xml, error, sizeof(error)); ASSERT_THAT(m, testing::NotNull()) << error; mjData* d = mj_makeData(m); mj_kinematics(m, d); mj_flex(m, d); mjtNum* metric = m->flex_stiffness + 21 * m->flex_elemadr[0]; // check that if the entire geometry is rescaled by a factor "scale", then // trace(strain^2) = 3*scale^2 for (mjtNum scale = 1; scale < 4; scale++) { for (int t = 0; t < m->flex_elemnum[0]; t++) { mjtNum energy = 0; mjtNum volume = 1./6.; int idx = 0; for (int e1 = 0; e1 < 6; e1++) { for (int e2 = e1; e2 < 6; e2++) { int idx1 = m->flex_elemedge[6*t+e1 + m->flex_elemedgeadr[0]]; int idx2 = m->flex_elemedge[6*t+e2 + m->flex_elemedgeadr[0]]; mjtNum elong1 = scale * m->flexedge_length0[idx1] * m->flexedge_length0[idx1]; mjtNum elong2 = scale * m->flexedge_length0[idx2] * m->flexedge_length0[idx2]; energy += metric[21*t+idx++] * elong1 * elong2 * (e1 == e2 ? 1. : 2.); } } EXPECT_NEAR( energy/volume, 3*scale*scale, std::numeric_limits::epsilon()); } } mj_deleteData(d); mj_deleteModel(m); } // -------------------------------- cable ----------------------------------- TEST_F(ElasticityTest, CantileverIntoCircle) { static constexpr char cantilever_xml[] = R"( )"; char error[1024] = {0}; mjModel* m = LoadModelFromString(cantilever_xml, error, sizeof(error)); ASSERT_THAT(m, testing::NotNull()) << error; mjData* d = mj_makeData(m); // see Oliver Weeger, Sai-Kit Yeung, Martin L. Dunn, "Isogeometric collocation methods for Cosserat rods and rod // structures", section 7.1 (DOI: j.cma.2016.05.009), the torque for achieving an angle phi is phi * E * Iy. mjtNum Iy = mjPI * pow(0.005, 4) / 4; mjtNum torque = 2 * mjPI * 1e9 * Iy; for (int i=0; i < 1300; i++) { if (i < 300) { d->ctrl[0] += torque / 300; } mj_step(m, d); } EXPECT_NEAR(d->sensordata[0], 0, std::numeric_limits::epsilon()); EXPECT_NEAR(d->sensordata[1], 0, std::numeric_limits::epsilon()); EXPECT_NEAR(d->sensordata[2], 1, std::numeric_limits::epsilon()); mj_deleteData(d); mj_deleteModel(m); } TEST_F(ElasticityTest, InvalidTxtAttribute) { static constexpr char cantilever_xml[] = R"( )"; char error[1024] = {0}; mjModel* m = LoadModelFromString(cantilever_xml, error, sizeof(error)); ASSERT_THAT(m, testing::IsNull()); } TEST_F(ElasticityTest, InvalidMixedAttribute) { static constexpr char cantilever_xml[] = R"( )"; char error[1024] = {0}; mjModel* m = LoadModelFromString(cantilever_xml, error, sizeof(error)); ASSERT_THAT(m, testing::IsNull()); } TEST_F(ElasticityTest, ValidAttributes) { static constexpr char cantilever_xml[] = R"( )"; char error[1024] = {0}; mjModel* m = LoadModelFromString(cantilever_xml, error, sizeof(error)); ASSERT_THAT(m, testing::NotNull()) << error; mj_deleteModel(m); } } // namespace } // namespace mujoco