1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
|
// Copyright 2021 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 engine/engine_support.c.
#include <string_view>
#include <gmock/gmock.h>
#include <gtest/gtest.h>
#include <mujoco/mujoco.h>
#include "test/fixture.h"
namespace mujoco {
namespace {
using ::testing::DoubleNear;
using JacobianTest = MujocoTest;
static const mjtNum max_abs_err = std::numeric_limits<float>::epsilon();
static constexpr char kJacobianTestingModel[] = R"(
<mujoco>
<worldbody>
<body name="distractor1" pos="0 0 .3">
<freejoint/>
<geom size=".1"/>
</body>
<body name="main">
<freejoint/>
<geom size=".1"/>
<body pos=".1 0 0">
<joint axis="0 1 0"/>
<geom type="capsule" size=".03" fromto="0 0 0 .2 0 0"/>
</body>
<body pos="0 .1 0">
<joint type="ball"/>
<geom type="capsule" size=".03" fromto="0 0 0 0 .2 0"/>
<body pos="0 .2 0">
<joint type="slide" axis="1 1 1"/>
<geom size=".05"/>
</body>
</body>
</body>
<body name="distractor2" pos="0 0 -.3">
<freejoint/>
<geom size=".1"/>
</body>
</worldbody>
</mujoco>
)";
// compare analytic and finite-differenced subtree-com Jacobian
TEST_F(JacobianTest, SubtreeJac) {
mjModel* model = LoadModelFromString(kJacobianTestingModel);
int nv = model->nv;
int bodyid = mj_name2id(model, mjOBJ_BODY, "main");
mjData* data = mj_makeData(model);
mjtNum* jac_subtree = (mjtNum*) mju_malloc(sizeof(mjtNum)*3*nv);
mjtNum* qpos = (mjtNum*) mju_malloc(sizeof(mjtNum)*model->nq);
mjtNum* nudge = (mjtNum*) mju_malloc(sizeof(mjtNum)*nv);
// all we need for Jacobians are kinematics and CoM-related quantitites
mj_kinematics(model, data);
mj_comPos(model, data);
// get subtree CoM Jacobian of free body
mj_jacSubtreeCom(model, data, jac_subtree, bodyid);
// save current subtree-com and qpos, clear nudge
mjtNum subtree_com[3];
mju_copy3(subtree_com, data->subtree_com+3*bodyid);
mju_copy(qpos, data->qpos, model->nq);
mju_zero(nudge, nv);
// compare analytic Jacobian to finite-difference approximation
static const mjtNum eps = 1e-6;
for (int i=0; i<nv; i++) {
// reset qpos, nudge i-th dof, update data->qpos, reset nudge
mju_copy(data->qpos, qpos, model->nq);
nudge[i] = 1;
mj_integratePos(model, data->qpos, nudge, eps);
nudge[i] = 0;
// kinematics and comPos to get nudged com
mj_kinematics(model, data);
mj_comPos(model, data);
// compare finite-differenced and analytic Jacobian
for (int j=0; j<3; j++) {
mjtNum findiff = (data->subtree_com[3*bodyid+j] - subtree_com[j]) / eps;
EXPECT_THAT(jac_subtree[nv*j+i], DoubleNear(findiff, eps));
}
}
mju_free(nudge);
mju_free(qpos);
mju_free(jac_subtree);
mj_deleteData(data);
mj_deleteModel(model);
}
// confirm that applying linear forces via the subtree-com Jacobian only creates
// the expected linear accelerations (no accelerations of internal joints)
TEST_F(JacobianTest, SubtreeJacNoInternalAcc) {
mjModel* model = LoadModelFromString(kJacobianTestingModel);
int nv = model->nv;
int bodyid = mj_name2id(model, mjOBJ_BODY, "main");
mjData* data = mj_makeData(model);
mjtNum* jac_subtree = (mjtNum*) mju_malloc(sizeof(mjtNum)*3*nv);
// all we need for Jacobians are kinematics and CoM-related quantitites
mj_kinematics(model, data);
mj_comPos(model, data);
// get subtree CoM Jacobian of free body
mj_jacSubtreeCom(model, data, jac_subtree, bodyid);
// uncomment for debugging
// mju_printMat(jac_subtree, 3, nv);
// call fwdPosition since we'll need the factorised mass matrix in the test
mj_fwdPosition(model, data);
// treating the subtree Jacobian as the projection of 3 axis-aligned unit
// forces into joint space, solve for the resulting accelerations in-place
mj_solveM(model, data, jac_subtree, jac_subtree, 3);
// expect to find accelerations of magnitude 1/subtreemass in the first 3
// coordinates of the free joint and 0s elsewhere, since applying forces to
// the CoM should accelerate the whole mechanism without any internal motion
int body_dofadr = model->body_dofadr[bodyid];
mjtNum invtreemass = 1.0/model->body_subtreemass[bodyid];
for (int r = 0; r < 3; r++) {
for (int c = 0; c < nv; c++) {
mjtNum expected = c - body_dofadr == r ? invtreemass : 0.0;
EXPECT_THAT(jac_subtree[nv*r+c], DoubleNear(expected, max_abs_err));
}
}
mju_free(jac_subtree);
mj_deleteData(data);
mj_deleteModel(model);
}
using VersionTest = MujocoTest;
const char *const kExpectedVersionString = "2.2.2";
TEST_F(VersionTest, MjVersion) {
EXPECT_EQ(mj_version(), mjVERSION_HEADER);
}
TEST_F(VersionTest, MjVersionString) {
EXPECT_EQ(std::string_view(mj_versionString()), kExpectedVersionString);
}
} // namespace
} // namespace mujoco
|
