ilqg_solver.h

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#ifndef EXOTICA_ILQG_SOLVER_ILQG_SOLVER_H_
#define EXOTICA_ILQG_SOLVER_ILQG_SOLVER_H_

#include <exotica_core/feedback_motion_solver.h>
#include <exotica_core/problems/dynamic_time_indexed_shooting_problem.h>
#include <exotica_core/server.h>
#include <Eigen/Eigenvalues>

#include <exotica_ilqg_solver/ilqg_solver_initializer.h>

namespace exotica
{
// This code is based on:
// E. Todorov, W. Li A generalized iterative LQG method for locally-optimal feedback
//      control of constrained nonlinear stochastic systems
// http://maeresearch.ucsd.edu/skelton/publications/weiwei_ilqg_CDC43.pdf
class ILQGSolver : public FeedbackMotionSolver, public Instantiable<ILQGSolverInitializer>
{
public:
    void Solve(Eigen::MatrixXd& solution) override;

    void SpecifyProblem(PlanningProblemPtr pointer) override;

    Eigen::VectorXd GetFeedbackControl(Eigen::VectorXdRefConst x, int t) const override;

private:
    DynamicTimeIndexedShootingProblemPtr prob_;       
    DynamicsSolverPtr dynamics_solver_;               
    std::vector<Eigen::MatrixXd> l_gains_, L_gains_;  

    Eigen::MatrixXd best_ref_x_, best_ref_u_;  

    void BackwardPass();

    double ForwardPass(const double alpha, Eigen::MatrixXdRefConst ref_x, Eigen::MatrixXdRefConst ref_u);
};
}  // namespace exotica

#endif  // EXOTICA_ILQG_SOLVER_ILQG_SOLVER_H_