test_EKF_imuSampling.cpp

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#include <gtest/gtest.h>
#include <math.h>
#include "EKF/ekf.h"

class EkfSamplingTestParametrized : public ::testing::TestWithParam<std::tuple<float,float>>
{
 public:

    Ekf _ekf{};

    uint32_t _t_us{0};

    // Setup the Ekf with synthetic measurements
    void SetUp() override
    {
        _ekf.init(0);

    }

    void TearDown() override
    {

    }
};

TEST_P(EkfSamplingTestParametrized, imuSamplingAtMultipleRates)
{
    // WHEN: adding imu samples at a higher rate than the update loop
    // THEN: imu sample should be down sampled
    // WHEN: adding imu samples at a same or lower rate than the update loop
    // THEN: imu sample should reach buffer unchanged

    uint32_t dt_us = std::get<0>(GetParam()) * (_ekf.FILTER_UPDATE_PERIOD_MS * 1000);
    uint32_t expected_dt_us = std::get<1>(GetParam()) * (_ekf.FILTER_UPDATE_PERIOD_MS * 1000);

    Vector3f ang_vel{0.0f,0.0f,0.0f};
    Vector3f accel{-0.46f,0.87f,0.0f};
    imuSample imu_sample;
    imu_sample.delta_ang_dt = dt_us * 1.e-6f;
    imu_sample.delta_ang = ang_vel * imu_sample.delta_ang_dt;
    imu_sample.delta_vel_dt = dt_us * 1.e-6f;
    imu_sample.delta_vel = accel * imu_sample.delta_vel_dt;

    // The higher the imu rate is the more measurements we have to set before reaching the FILTER_UPDATE_PERIOD
    for(int i = 0; i<(int)20/std::get<0>(GetParam()); ++i)
    {
        imu_sample.time_us = _t_us;
        _ekf.setIMUData(imu_sample);
        _t_us += dt_us;
    }

    // Get the imu sample that was put into the buffer
    imuSample imu_sample_buffered = _ekf.get_imu_sample_delayed();
    EXPECT_NEAR(expected_dt_us / 1e6f, imu_sample_buffered.delta_ang_dt, 1e-5f);
    EXPECT_NEAR(expected_dt_us / 1e6f, imu_sample_buffered.delta_vel_dt, 1e-5f);

    // WHEN: downsampling the imu measurement
    // THEN: the delta vel should be accumulated correctly
    EXPECT_NEAR(ang_vel(0), imu_sample_buffered.delta_ang(0)/imu_sample_buffered.delta_ang_dt, 1e-3f);
    EXPECT_NEAR(ang_vel(1), imu_sample_buffered.delta_ang(1)/imu_sample_buffered.delta_ang_dt, 1e-3f);
    EXPECT_NEAR(ang_vel(2), imu_sample_buffered.delta_ang(2)/imu_sample_buffered.delta_ang_dt, 1e-3f);
    EXPECT_NEAR(accel(0), imu_sample_buffered.delta_vel(0)/imu_sample_buffered.delta_vel_dt, 1e-3f);
    EXPECT_NEAR(accel(1), imu_sample_buffered.delta_vel(1)/imu_sample_buffered.delta_vel_dt, 1e-3f);
    EXPECT_NEAR(accel(2), imu_sample_buffered.delta_vel(2)/imu_sample_buffered.delta_vel_dt, 1e-3f);

}

INSTANTIATE_TEST_CASE_P(imuSamplingAtMultipleRates,
            EkfSamplingTestParametrized,
            ::testing::Values(
                std::make_tuple<float,float>(1.0f,1.0f),
                std::make_tuple<float,float>(1.6f,1.6f),
                std::make_tuple<float,float>(0.333f,1.0f)
            ));