propagator.hpp

// Copyright (C) 2023 Alessandro Fornasier.
// Control of Networked Systems, University of Klagenfurt, Austria.
//
// All rights reserved.
//
// This software is licensed under the terms of 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.
//
// You can contact the authors at <alessandro.fornasier@ieee.org>
 
#ifndef PROPAGATOR_HPP
#define PROPAGATOR_HPP
 
#include "msceqf/options/msceqf_options.hpp"
#include "msceqf/symmetry/symmetry.hpp"
#include "sensors/sensor_data.hpp"
#include "msceqf/state/state.hpp"
#include "types/fptypes.hpp"
#include "utils/tools.hpp"
 
namespace msceqf
{
class Propagator
{
 public:
  using ImuBuffer = std::deque<Imu>;  

  Propagator(const PropagatorOptions& opts);

  void insertImu(MSCEqFState& X, const SystemState& xi0, const Imu& imu, fp& timestamp);

  bool propagate(MSCEqFState& X, const SystemState& xi0, fp& timestamp, const fp& new_timestamp);
 
 private:
  ImuBuffer getImuReadings(const fp& t0, const fp& t1);

  Imu lerp(const Imu& pre, const Imu& post, const fp& alpha);

  void propagateMean(MSCEqFState& X, const SystemState& xi0, const Imu& u, const fp& dt);

  void propagateCovariance(MSCEqFState& X, const SystemState& xi0, const Imu& u, const fp& dt);

  const MatrixX stateMatrix(MSCEqFState& X, const SystemState& xi0, const Imu& u) const;

  const MatrixX inputMatrix(MSCEqFState& X, const SystemState& xi0) const;

  const MatrixX discreteTimeMatrix(const MatrixX& A, const MatrixX& B, const fp& dt) const;
 
  ImuBuffer imu_buffer_;  
  Matrix12 Q_;            
 
  int state_transition_order_;  
  uint imu_buffer_max_size_;    
 
  std::mutex mutex_;  
 
  static constexpr fp eps_ = 1e-6;  
};
 
}  // namespace msceqf
 
#endif  // PROPAGATOR_HPP