nlp_formulation.cc

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#include <towr/nlp_formulation.h>

#include <towr/variables/variable_names.h>
#include <towr/variables/phase_durations.h>

#include <towr/constraints/base_motion_constraint.h>
#include <towr/constraints/dynamic_constraint.h>
#include <towr/constraints/force_constraint.h>
#include <towr/constraints/range_of_motion_constraint.h>
#include <towr/constraints/swing_constraint.h>
#include <towr/constraints/terrain_constraint.h>
#include <towr/constraints/total_duration_constraint.h>
#include <towr/constraints/spline_acc_constraint.h>

#include <towr/costs/node_cost.h>
#include <towr/variables/nodes_variables_all.h>

#include <iostream>

namespace towr {

NlpFormulation::NlpFormulation ()
{
  using namespace std;
  cout << "\n";
  cout << "************************************************************\n";
  cout << " TOWR - Trajectory Optimization for Walking Robots (v1.4)\n";
  cout << "                \u00a9 Alexander W. Winkler\n";
  cout << "           https://github.com/ethz-adrl/towr\n";
  cout << "************************************************************";
  cout << "\n\n";
}

NlpFormulation::VariablePtrVec
NlpFormulation::GetVariableSets (SplineHolder& spline_holder)
{
  VariablePtrVec vars;

  auto base_motion = MakeBaseVariables();
  vars.insert(vars.end(), base_motion.begin(), base_motion.end());

  auto ee_motion = MakeEndeffectorVariables();
  vars.insert(vars.end(), ee_motion.begin(), ee_motion.end());

  auto ee_force = MakeForceVariables();
  vars.insert(vars.end(), ee_force.begin(), ee_force.end());

  auto contact_schedule = MakeContactScheduleVariables();
  // can also just be fixed timings that aren't optimized over, but still added
  // to spline_holder.
  if (params_.IsOptimizeTimings()) {
    vars.insert(vars.end(), contact_schedule.begin(), contact_schedule.end());
  }

  // stores these readily constructed spline
  spline_holder = SplineHolder(base_motion.at(0), // linear
                               base_motion.at(1), // angular
                               params_.GetBasePolyDurations(),
                               ee_motion,
                               ee_force,
                               contact_schedule,
                               params_.IsOptimizeTimings());
  return vars;
}

std::vector<NodesVariables::Ptr>
NlpFormulation::MakeBaseVariables () const
{
  std::vector<NodesVariables::Ptr> vars;

  int n_nodes = params_.GetBasePolyDurations().size() + 1;

  auto spline_lin = std::make_shared<NodesVariablesAll>(n_nodes, k3D, id::base_lin_nodes);

  double x = final_base_.lin.p().x();
  double y = final_base_.lin.p().y();
  double z = terrain_->GetHeight(x,y) - model_.kinematic_model_->GetNominalStanceInBase().front().z();
  Vector3d final_pos(x, y, z);

  spline_lin->SetByLinearInterpolation(initial_base_.lin.p(), final_pos, params_.GetTotalTime());
  spline_lin->AddStartBound(kPos, {X,Y,Z}, initial_base_.lin.p());
  spline_lin->AddStartBound(kVel, {X,Y,Z}, initial_base_.lin.v());
  spline_lin->AddFinalBound(kPos, params_.bounds_final_lin_pos_,   final_base_.lin.p());
  spline_lin->AddFinalBound(kVel, params_.bounds_final_lin_vel_, final_base_.lin.v());
  vars.push_back(spline_lin);

  auto spline_ang = std::make_shared<NodesVariablesAll>(n_nodes, k3D, id::base_ang_nodes);
  spline_ang->SetByLinearInterpolation(initial_base_.ang.p(), final_base_.ang.p(), params_.GetTotalTime());
  spline_ang->AddStartBound(kPos, {X,Y,Z}, initial_base_.ang.p());
  spline_ang->AddStartBound(kVel, {X,Y,Z}, initial_base_.ang.v());
  spline_ang->AddFinalBound(kPos, params_.bounds_final_ang_pos_, final_base_.ang.p());
  spline_ang->AddFinalBound(kVel, params_.bounds_final_ang_vel_, final_base_.ang.v());
  vars.push_back(spline_ang);

  return vars;
}

std::vector<NodesVariablesPhaseBased::Ptr>
NlpFormulation::MakeEndeffectorVariables () const
{
  std::vector<NodesVariablesPhaseBased::Ptr> vars;

  // Endeffector Motions
  double T = params_.GetTotalTime();
  for (int ee=0; ee<params_.GetEECount(); ee++) {
    auto nodes = std::make_shared<NodesVariablesEEMotion>(
                                              params_.GetPhaseCount(ee),
                                              params_.ee_in_contact_at_start_.at(ee),
                                              id::EEMotionNodes(ee),
                                              params_.ee_polynomials_per_swing_phase_);

    // initialize towards final footholds
    double yaw = final_base_.ang.p().z();
    Eigen::Vector3d euler(0.0, 0.0, yaw);
    Eigen::Matrix3d w_R_b = EulerConverter::GetRotationMatrixBaseToWorld(euler);
    Vector3d final_ee_pos_W = final_base_.lin.p() + w_R_b*model_.kinematic_model_->GetNominalStanceInBase().at(ee);
    double x = final_ee_pos_W.x();
    double y = final_ee_pos_W.y();
    double z = terrain_->GetHeight(x,y);
    nodes->SetByLinearInterpolation(initial_ee_W_.at(ee), Vector3d(x,y,z), T);

    nodes->AddStartBound(kPos, {X,Y,Z}, initial_ee_W_.at(ee));
    vars.push_back(nodes);
  }

  return vars;
}

std::vector<NodesVariablesPhaseBased::Ptr>
NlpFormulation::MakeForceVariables () const
{
  std::vector<NodesVariablesPhaseBased::Ptr> vars;

  double T = params_.GetTotalTime();
  for (int ee=0; ee<params_.GetEECount(); ee++) {
    auto nodes = std::make_shared<NodesVariablesEEForce>(
                                              params_.GetPhaseCount(ee),
                                              params_.ee_in_contact_at_start_.at(ee),
                                              id::EEForceNodes(ee),
                                              params_.force_polynomials_per_stance_phase_);

    // initialize with mass of robot distributed equally on all legs
    double m = model_.dynamic_model_->m();
    double g = model_.dynamic_model_->g();

    Vector3d f_stance(0.0, 0.0, m*g/params_.GetEECount());
    nodes->SetByLinearInterpolation(f_stance, f_stance, T); // stay constant
    vars.push_back(nodes);
  }

  return vars;
}

std::vector<PhaseDurations::Ptr>
NlpFormulation::MakeContactScheduleVariables () const
{
  std::vector<PhaseDurations::Ptr> vars;

  for (int ee=0; ee<params_.GetEECount(); ee++) {
    auto var = std::make_shared<PhaseDurations>(ee,
                                                params_.ee_phase_durations_.at(ee),
                                                params_.ee_in_contact_at_start_.at(ee),
                                                params_.bound_phase_duration_.first,
                                                params_.bound_phase_duration_.second);
    vars.push_back(var);
  }

  return vars;
}

NlpFormulation::ContraintPtrVec
NlpFormulation::GetConstraints(const SplineHolder& spline_holder) const
{
  ContraintPtrVec constraints;
  for (auto name : params_.constraints_)
    for (auto c : GetConstraint(name, spline_holder))
      constraints.push_back(c);

  return constraints;
}

NlpFormulation::ContraintPtrVec
NlpFormulation::GetConstraint (Parameters::ConstraintName name,
                           const SplineHolder& s) const
{
  switch (name) {
    case Parameters::Dynamic:        return MakeDynamicConstraint(s);
    case Parameters::EndeffectorRom: return MakeRangeOfMotionBoxConstraint(s);
    case Parameters::BaseRom:        return MakeBaseRangeOfMotionConstraint(s);
    case Parameters::TotalTime:      return MakeTotalTimeConstraint();
    case Parameters::Terrain:        return MakeTerrainConstraint();
    case Parameters::Force:          return MakeForceConstraint();
    case Parameters::Swing:          return MakeSwingConstraint();
    case Parameters::BaseAcc:        return MakeBaseAccConstraint(s);
    default: throw std::runtime_error("constraint not defined!");
  }
}


NlpFormulation::ContraintPtrVec
NlpFormulation::MakeBaseRangeOfMotionConstraint (const SplineHolder& s) const
{
  return {std::make_shared<BaseMotionConstraint>(params_.GetTotalTime(),
                                                 params_.dt_constraint_base_motion_,
                                                 s)};
}

NlpFormulation::ContraintPtrVec
NlpFormulation::MakeDynamicConstraint(const SplineHolder& s) const
{
  auto constraint = std::make_shared<DynamicConstraint>(model_.dynamic_model_,
                                                        params_.GetTotalTime(),
                                                        params_.dt_constraint_dynamic_,
                                                        s);
  return {constraint};
}

NlpFormulation::ContraintPtrVec
NlpFormulation::MakeRangeOfMotionBoxConstraint (const SplineHolder& s) const
{
  ContraintPtrVec c;

  for (int ee=0; ee<params_.GetEECount(); ee++) {
    auto rom = std::make_shared<RangeOfMotionConstraint>(model_.kinematic_model_,
                                                         params_.GetTotalTime(),
                                                         params_.dt_constraint_range_of_motion_,
                                                         ee,
                                                         s);
    c.push_back(rom);
  }

  return c;
}

NlpFormulation::ContraintPtrVec
NlpFormulation::MakeTotalTimeConstraint () const
{
  ContraintPtrVec c;
  double T = params_.GetTotalTime();

  for (int ee=0; ee<params_.GetEECount(); ee++) {
    auto duration_constraint = std::make_shared<TotalDurationConstraint>(T, ee);
    c.push_back(duration_constraint);
  }

  return c;
}

NlpFormulation::ContraintPtrVec
NlpFormulation::MakeTerrainConstraint () const
{
  ContraintPtrVec constraints;

  for (int ee=0; ee<params_.GetEECount(); ee++) {
    auto c = std::make_shared<TerrainConstraint>(terrain_, id::EEMotionNodes(ee));
    constraints.push_back(c);
  }

  return constraints;
}

NlpFormulation::ContraintPtrVec
NlpFormulation::MakeForceConstraint () const
{
  ContraintPtrVec constraints;

  for (int ee=0; ee<params_.GetEECount(); ee++) {
    auto c = std::make_shared<ForceConstraint>(terrain_,
                                               params_.force_limit_in_normal_direction_,
                                               ee);
    constraints.push_back(c);
  }

  return constraints;
}

NlpFormulation::ContraintPtrVec
NlpFormulation::MakeSwingConstraint () const
{
  ContraintPtrVec constraints;

  for (int ee=0; ee<params_.GetEECount(); ee++) {
    auto swing = std::make_shared<SwingConstraint>(id::EEMotionNodes(ee));
    constraints.push_back(swing);
  }

  return constraints;
}

NlpFormulation::ContraintPtrVec
NlpFormulation::MakeBaseAccConstraint (const SplineHolder& s) const
{
  ContraintPtrVec constraints;

  constraints.push_back(std::make_shared<SplineAccConstraint>
                        (s.base_linear_, id::base_lin_nodes));

  constraints.push_back(std::make_shared<SplineAccConstraint>
                        (s.base_angular_, id::base_ang_nodes));

  return constraints;
}

NlpFormulation::ContraintPtrVec
NlpFormulation::GetCosts() const
{
  ContraintPtrVec costs;
  for (const auto& pair : params_.costs_)
    for (auto c : GetCost(pair.first, pair.second))
      costs.push_back(c);

  return costs;
}

NlpFormulation::CostPtrVec
NlpFormulation::GetCost(const Parameters::CostName& name, double weight) const
{
  switch (name) {
    case Parameters::ForcesCostID:   return MakeForcesCost(weight);
    case Parameters::EEMotionCostID: return MakeEEMotionCost(weight);
    default: throw std::runtime_error("cost not defined!");
  }
}

NlpFormulation::CostPtrVec
NlpFormulation::MakeForcesCost(double weight) const
{
  CostPtrVec cost;

  for (int ee=0; ee<params_.GetEECount(); ee++)
    cost.push_back(std::make_shared<NodeCost>(id::EEForceNodes(ee), kPos, Z, weight));

  return cost;
}

NlpFormulation::CostPtrVec
NlpFormulation::MakeEEMotionCost(double weight) const
{
  CostPtrVec cost;

  for (int ee=0; ee<params_.GetEECount(); ee++) {
    cost.push_back(std::make_shared<NodeCost>(id::EEMotionNodes(ee), kVel, X, weight));
    cost.push_back(std::make_shared<NodeCost>(id::EEMotionNodes(ee), kVel, Y, weight));
  }

  return cost;
}

} /* namespace towr */