diff --git a/src/modules/ekf2/EKF/imu_down_sampler/imu_down_sampler.cpp b/src/modules/ekf2/EKF/imu_down_sampler/imu_down_sampler.cpp index 0054f917f3..d1383525ae 100644 --- a/src/modules/ekf2/EKF/imu_down_sampler/imu_down_sampler.cpp +++ b/src/modules/ekf2/EKF/imu_down_sampler/imu_down_sampler.cpp @@ -7,44 +7,38 @@ ImuDownSampler::ImuDownSampler(int32_t &target_dt_us) : _target_dt_us(target_dt_ reset(); } -// integrate imu samples until target dt reached -// assumes that dt of the gyroscope is close to the dt of the accelerometer -// returns true if target dt is reached -bool ImuDownSampler::update(const imuSample &imu_sample_new) +bool ImuDownSampler::update(const imuSample &imu) { - _delta_ang_dt_avg = 0.9f * _delta_ang_dt_avg + 0.1f * imu_sample_new.delta_ang_dt; + _delta_ang_dt_avg = 0.9f * _delta_ang_dt_avg + 0.1f * imu.delta_ang_dt; // accumulate time deltas - _imu_down_sampled.time_us = imu_sample_new.time_us; - _imu_down_sampled.delta_ang_dt += imu_sample_new.delta_ang_dt; - _imu_down_sampled.delta_vel_dt += imu_sample_new.delta_vel_dt; - _imu_down_sampled.delta_vel_clipping[0] |= imu_sample_new.delta_vel_clipping[0]; - _imu_down_sampled.delta_vel_clipping[1] |= imu_sample_new.delta_vel_clipping[1]; - _imu_down_sampled.delta_vel_clipping[2] |= imu_sample_new.delta_vel_clipping[2]; - - // use a quaternion to accumulate delta angle data - // this quaternion represents the rotation from the start to end of the accumulation period - const Quatf delta_q(AxisAnglef(imu_sample_new.delta_ang)); - _delta_angle_accumulated = _delta_angle_accumulated * delta_q; - _delta_angle_accumulated.normalize(); - - // rotate the accumulated delta velocity data forward each time so it is always in the updated rotation frame - const Dcmf delta_R(delta_q.inversed()); - _imu_down_sampled.delta_vel = delta_R * _imu_down_sampled.delta_vel; - - // accumulate the most recent delta velocity data at the updated rotation frame - // assume effective sample time is halfway between the previous and current rotation frame - _imu_down_sampled.delta_vel += (imu_sample_new.delta_vel + delta_R * imu_sample_new.delta_vel) * 0.5f; + _imu_down_sampled.time_us = imu.time_us; + _imu_down_sampled.delta_ang += imu.delta_ang; + _imu_down_sampled.delta_vel += imu.delta_vel; + _imu_down_sampled.delta_ang_dt += imu.delta_ang_dt; + _imu_down_sampled.delta_vel_dt += imu.delta_vel_dt; + _imu_down_sampled.delta_vel_clipping[0] |= imu.delta_vel_clipping[0]; + _imu_down_sampled.delta_vel_clipping[1] |= imu.delta_vel_clipping[1]; + _imu_down_sampled.delta_vel_clipping[2] |= imu.delta_vel_clipping[2]; _accumulated_samples++; - // required number of samples accumulated and the total time is at least half of the target // OR total time already exceeds the target - if ((_accumulated_samples >= _required_samples && _imu_down_sampled.delta_ang_dt > _min_dt_s) - || (_imu_down_sampled.delta_ang_dt > _target_dt_s)) { - _imu_down_sampled.delta_ang = AxisAnglef(_delta_angle_accumulated); + // target dt in seconds safely constrained + const float constrained_target_dt_s = math::constrain(_target_dt_us, (int32_t)1000, (int32_t)100000) * 1e-6f; + const int required_samples = math::max((int)roundf(constrained_target_dt_s / _delta_ang_dt_avg), 1); + + float target_dt_s = required_samples * _delta_ang_dt_avg; + + // minimum delta angle dt (in addition to number of samples) + float min_dt_s = math::max(_delta_ang_dt_avg * (required_samples - 1.f), _delta_ang_dt_avg * 0.5f); + + if ((_accumulated_samples >= required_samples && _imu_down_sampled.delta_ang_dt > min_dt_s) + || (_imu_down_sampled.delta_ang_dt > target_dt_s) + ) { + return true; } @@ -54,16 +48,5 @@ bool ImuDownSampler::update(const imuSample &imu_sample_new) void ImuDownSampler::reset() { _imu_down_sampled = {}; - _delta_angle_accumulated.setIdentity(); _accumulated_samples = 0; - - // target dt in seconds safely constrained - float target_dt_s = math::constrain(_target_dt_us, (int32_t)1000, (int32_t)100000) * 1e-6f; - - _required_samples = math::max((int)roundf(target_dt_s / _delta_ang_dt_avg), 1); - - _target_dt_s = _required_samples * _delta_ang_dt_avg; - - // minimum delta angle dt (in addition to number of samples) - _min_dt_s = math::max(_delta_ang_dt_avg * (_required_samples - 1.f), _delta_ang_dt_avg * 0.5f); } diff --git a/src/modules/ekf2/EKF/imu_down_sampler/imu_down_sampler.hpp b/src/modules/ekf2/EKF/imu_down_sampler/imu_down_sampler.hpp index 8f0c4211be..8587e7f9b7 100644 --- a/src/modules/ekf2/EKF/imu_down_sampler/imu_down_sampler.hpp +++ b/src/modules/ekf2/EKF/imu_down_sampler/imu_down_sampler.hpp @@ -51,6 +51,8 @@ public: explicit ImuDownSampler(int32_t &target_dt_us); ~ImuDownSampler() = default; + // integrate imu samples until target dt reached + // returns true if target dt is reached bool update(const imuSample &imu_sample_new); imuSample getDownSampledImuAndTriggerReset() @@ -64,16 +66,10 @@ private: void reset(); imuSample _imu_down_sampled{}; - Quatf _delta_angle_accumulated{}; - int _accumulated_samples{0}; - int _required_samples{1}; int32_t &_target_dt_us; - float _target_dt_s{0.010f}; - float _min_dt_s{0.005f}; - float _delta_ang_dt_avg{0.005f}; }; #endif // !EKF_IMU_DOWN_SAMPLER_HPP