feasibility_driven_ddp_solver.h

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#ifndef EXOTICA_DDP_SOLVER_FEASIBILITY_DRIVEN_DDP_SOLVER_H_
#define EXOTICA_DDP_SOLVER_FEASIBILITY_DRIVEN_DDP_SOLVER_H_
 
#include <exotica_ddp_solver/abstract_ddp_solver.h>
#include <exotica_ddp_solver/feasibility_driven_ddp_solver_initializer.h>
 
namespace exotica
{
// Feasibility-driven DDP solver
// Based on the implementation in Crocoddyl: https://github.com/loco-3d/crocoddyl.git
// Cf. https://arxiv.org/abs/1909.04947
class AbstractFeasibilityDrivenDDPSolver : public AbstractDDPSolver
{
public:
    void Solve(Eigen::MatrixXd& solution) override;
    void SpecifyProblem(PlanningProblemPtr pointer) override;
 
    const std::vector<Eigen::VectorXd>& get_fs() const { return fs_; };
    const std::vector<Eigen::VectorXd>& get_xs() const { return xs_; };
    const std::vector<Eigen::VectorXd>& get_us() const { return us_; };
 
protected:
    int NDX_;
    int last_T_ = -1;
 
    void IncreaseRegularization() override;
    void DecreaseRegularization() override;
    const Eigen::Vector2d& ExpectedImprovement();
    void UpdateExpectedImprovement();
    inline bool IsNaN(const double value)
    {
        if (std::isnan(value) || std::isinf(value) || value >= 1e30)
        {
            return true;
        }
        else
        {
            return false;
        }
    }
    void SetCandidate(const std::vector<Eigen::VectorXd>& xs_warm, const std::vector<Eigen::VectorXd>& us_warm, const bool is_feasible);
    double CheckStoppingCriteria();
 
    double CalcDiff();
    bool ComputeDirection(const bool recalcDiff);
    virtual bool BackwardPassFDDP();
    void BackwardPass() override { return (void)BackwardPassFDDP(); }
    virtual void ComputeGains(const int t);
    void ForwardPass(const double steplength);
    double TryStep(const double steplength);
 
    virtual void AllocateData();
 
    Eigen::MatrixXd control_limits_;
    double initial_regularization_rate_ = 1e-9;             // Set from parameters on Instantiate
    bool clamp_to_control_limits_in_forward_pass_ = false;  // Set from parameters on Instantiate
 
    double steplength_;                  
    Eigen::Vector2d d_;                  
    double dV_;                          
    double dVexp_;                       
    double th_acceptstep_ = 0.1;         
    double th_stop_ = 1e-9;              
    double th_gradient_tolerance_ = 0.;  
    double stop_;                        
 
    double dg_ = 0.;
    double dq_ = 0.;
    double dv_ = 0.;
    double th_acceptnegstep_ = 2.;  
    std::vector<Eigen::VectorXd> us_;
    std::vector<Eigen::VectorXd> xs_;
    bool is_feasible_ = false;
    double xreg_ = 1e-9;      
    double ureg_ = 1e-9;      
    double regmin_ = 1e-9;    
    double regmax_ = 1e9;     
    double regfactor_ = 10.;  
 
    std::vector<Eigen::VectorXd> xs_try_;  
    std::vector<Eigen::VectorXd> us_try_;  
    std::vector<Eigen::VectorXd> dx_;
 
    // allocate data
    std::vector<Eigen::VectorXd> fs_;  
 
    Eigen::VectorXd xnext_;
    Eigen::MatrixXd FxTVxx_p_;
    std::vector<Eigen::MatrixXd> FuTVxx_p_;
    std::vector<Eigen::MatrixXd> Qxu_;
    Eigen::VectorXd fTVxx_p_;
    std::vector<Eigen::LDLT<Eigen::MatrixXd> > Quu_ldlt_;
    std::vector<Eigen::VectorXd> Quuk_;
    double th_grad_ = 1e-12;     
    double th_stepdec_ = 0.5;    
    double th_stepinc_ = 0.01;   
    bool was_feasible_ = false;  
};
 
class FeasibilityDrivenDDPSolver : public AbstractFeasibilityDrivenDDPSolver, public Instantiable<FeasibilityDrivenDDPSolverInitializer>
{
public:
    void Instantiate(const FeasibilityDrivenDDPSolverInitializer& init) override;
};
 
}  // namespace exotica
 
#endif  // EXOTICA_DDP_SOLVER_FEASIBILITY_DRIVEN_DDP_SOLVER_H_