Test ImuTracker (#711)

Adds unit tests for ImuTracker to cover filtering of the gravity
vector and tracking angular velocity.

cartographer/mapping/imu_tracker_test.cc

@@ -0,0 +1,95 @@
+/*
+ * Copyright 2017 The Cartographer Authors
+ *
+ * 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.
+ */
+
+#include "cartographer/mapping/imu_tracker.h"
+
+#include "cartographer/common/make_unique.h"
+#include "gtest/gtest.h"
+
+namespace cartographer {
+namespace mapping {
+namespace {
+
+constexpr double kDuration = 3.f;
+constexpr double kGravityTimeConstant = 0.1 * kDuration;
+constexpr double kPrecision = 1e-8;
+constexpr int kSteps = 10;
+
+class ImuTrackerTest : public ::testing::Test {
+ protected:
+  void SetUp() override {
+    imu_tracker_ = common::make_unique<ImuTracker>(kGravityTimeConstant, time_);
+    angular_velocity_ = Eigen::Vector3d(0, 0, 0);
+    linear_acceleration_ = Eigen::Vector3d(0, 0, 9.9);
+    EXPECT_NEAR(0.,
+                imu_tracker_->orientation().angularDistance(
+                    Eigen::Quaterniond::Identity()),
+                kPrecision);
+  }
+
+  void AdvanceImu() {
+    for (int i = 0; i < kSteps; ++i) {
+      imu_tracker_->AddImuLinearAccelerationObservation(linear_acceleration_);
+      imu_tracker_->AddImuAngularVelocityObservation(angular_velocity_);
+      time_ += common::FromSeconds(kDuration / kSteps);
+      imu_tracker_->Advance(time_);
+    }
+    EXPECT_EQ(time_, imu_tracker_->time());
+  }
+
+  Eigen::Vector3d angular_velocity_;
+  std::unique_ptr<ImuTracker> imu_tracker_;
+  Eigen::Vector3d linear_acceleration_;
+  common::Time time_ = common::FromUniversal(12345678);
+};
+
+TEST_F(ImuTrackerTest, IntegrateYawRotation) {
+  angular_velocity_ = Eigen::Vector3d(0, 0, 0.3);
+  AdvanceImu();
+  Eigen::Quaterniond expected_orientation(Eigen::AngleAxisd(
+      kDuration * angular_velocity_.norm(), angular_velocity_.normalized()));
+  EXPECT_NEAR(0.,
+              imu_tracker_->orientation().angularDistance(expected_orientation),
+              kPrecision);
+}
+
+TEST_F(ImuTrackerTest, IntegrateFullRotation) {
+  angular_velocity_ = Eigen::Vector3d(0.1, 0.4, 0.1);
+  // Using a huge gravity time constant effectively disables gravity vector
+  // tracking.
+  imu_tracker_.reset(new ImuTracker(1e10 * kDuration, time_));
+  AdvanceImu();
+  Eigen::Quaterniond expected_orientation(Eigen::AngleAxisd(
+      kDuration * angular_velocity_.norm(), angular_velocity_.normalized()));
+  EXPECT_NEAR(0.,
+              imu_tracker_->orientation().angularDistance(expected_orientation),
+              kPrecision);
+}
+
+TEST_F(ImuTrackerTest, LearnGravityVector) {
+  linear_acceleration_ = Eigen::Vector3d(0.5, 0.3, 9.5);
+  AdvanceImu();
+  Eigen::Quaterniond expected_orientation;
+  expected_orientation.setFromTwoVectors(linear_acceleration_,
+                                         Eigen::Vector3d::UnitZ());
+  EXPECT_NEAR(0.,
+              imu_tracker_->orientation().angularDistance(expected_orientation),
+              kPrecision);
+}
+
+}  // namespace
+}  // namespace mapping
+}  // namespace cartographer